An important new research article appeared yesterday, in the online edition of Future Medicine: Spontaneous reversal of the developmental aging of normal human cells following transcriptional reprogramming. The study is important because it contradicts an important earlier assumption about induced pluripotent stem cells (iPSCs).  It contradicts the assumption that reverting a cell to iPSC status restores the expression of telomerase and telomere length to equivalent embryonic stem cell length. 

(Note: hiPSCs stands for human iPSCs, hESCs stands for human embryonic stem cells)

In my February 2010 blog post IPSCs, telomerase, and closing the loop in the stem cell supply chain I related “The 2009 study Telomeres Acquire Embryonic Stem Cell Characteristics in Induced Pluripotent Stem Cells was important in that it showed that reversion of cells to iPSC status fully restores telomerase activity to iPSCs, equivalent to that in embryonic stem cells (ESCs). “We show here that telomeres are elongated in iPS cells compared to the parental differentiated cells both when using four (Oct3/4, Sox2, Klf4, cMyc) or three (Oct3/4, Sox2, Klf4) reprogramming factors and both from young and aged individuals.  We demonstrate genetically that, during reprogramming, telomere elongation is usually mediated by telomerase and that iPS telomeres acquire the epigenetic marks of ES cells, including a low density of trimethylated histones H3K9 and H4K20 and increased abundance of telomere transcripts. Finally, reprogramming efficiency of cells derived from increasing generations of telomerase-deficient mice shows a dramatic decrease in iPS cell efficiency, a defect that is restored by telomerase reintroduction.”  The study related to mouse cells. Further, the 2009 publication Balancing Out the Ends during iPSC Nuclear Reprogramming discusses how “telomere length maintenance and long-term proliferative capacity of iPSCs is dependent on telomerase,” and concludes “Although a number of hurdles must still be cleared before iPS-based cell therapy becomes practical, the results (cited above) suggest that reprogramming of telomerase and telomeres may not be one them.” Finally, this 2009 study concluded “While these results reveal some heterogeneity in the reprogramming process with respect to telomere length, human somatic cells reprogrammed to pluripotency generally displayed elongated telomeres that suggest that they will not age prematurely when isolated from subjects of essentially any age. While these results reveal some heterogeneity in the reprogramming process with respect to telomere length, human somatic cells reprogrammed to pluripotency generally displayed elongated telomeres that suggest that they will not age prematurely when isolated from subjects of essentially any age.”  All of this seems now to be largely thrown out of the window.

The new study, based on carefully contrived experimental procedures, concludes the opposite is true for human iPSC cells: they generally end up with shorter telomeres than hESCs, telomeres of lengths commensurate with those of the adult cells which were originally reverted to make the iPSCs . “Aim: To determine whether transcriptional reprogramming is capable of reversing the developmental aging of normal human somatic cells to an embryonic state. Materials & methods: An isogenic system was utilized to facilitate an accurate assessment of the reprogramming of telomere restriction fragment (TRF) length of aged differentiated cells to that of the human embryonic stem (hES) cell line from which they were originally derived. An hES-derived mortal clonal cell strain EN13 was reprogrammed by SOX2, OCT4 and KLF4. The six resulting induced pluripotent stem (iPS) cell lines were surveyed for telomere length, telomerase activity and telomere-related gene expression. In addition, we measured all these parameters in widely-used hES and iPS cell lines and compared the results to those obtained in the six new isogenic iPS cell lines. — Results: We observed variable but relatively long TRF lengths in three widely studied hES cell lines (16.09–21.1 kb) but markedly shorter TRF lengths (6.4–12.6 kb) in five similarly widely studied iPS cell lines. Transcriptome analysis comparing these hES and iPS cell lines showed modest variation in a small subset of genes implicated in telomere length regulation. However, iPS cell lines consistently showed reduced levels of telomerase activity compared with hES cell lines.” 

The new study says restoring a cell to pluripotency and providing the cell with youth are two quite different things and the former does not necessarily imply the latter.  Pluripotency of an iPSC implies that, like an embryonic stem cell, the iPSC can differentiate into any somatic cell type.  Absence of youth in this case means that the restored iPSC cell could probably not lead to many generations of descendents like an embryonic stem cell could,  because its telomere lengths are short like those in old cells.   In fact, iPSC cells can be near senescent. 

As related in the new study report “– recently, the focus of reprogramming research has shifted to defined transcriptional methods, that is, the exogenous expression of transcription factors critical to germline gene expression such as MYC, KLF4, OCT4 and SOX2 [29], or LIN28, NANOG, OCT4 and SOX2 [30]. When introduced into somatic cells, varied combinations of these genes or complementing small molecules are capable of altering the differentiated state of somatic cells, leading to induced pluripotent stem (iPS) cells similar to hES cells. This facile, cost-effective and ethically nonproblematic means of potentially manufacturing a host of transplantable patient-specific cells has led to numerous studies of iPS cell pluripotency.  However, there is little research on the effects of transcriptional reprogramming on cellular aging, in particular on telomere length regulation.”   

In other words, the iPSC researchers and the telomerase researchers were paying insufficient attention to each other.  Telomerase expression and iPSC stem cells are each central to a theory of aging treated in my treatise, Telomere Shortening and Damage and Stem Cell Supply Chain Breakdown.  I have reviewed hundreds of papers related to these topics and my impression is that not paying attention to what the other guys are researching is more the general rule than the exception.  

The researchers in the new study used cells from a single genetic source to sort through what could be a very confusing situation.  “ — In the case of human cells, there are contradictory reports as to the aged status of reprogrammed cells [32–34]. This confusion may be due, in part, to the genetic variability in the subtelomeric ‘X’ region of telomere restriction fragments (TRFs) [35,36], often complicating comparisons of TRF length in differing genotypes. “We therefore undertook an analysis of telomere dynamics during transcriptional reprogramming in an isogenic background of the hES-derived clonal embryonic progenitor cell line EN13, such that TRF length can be measured and compared with both the starting somatic cells (EN13) and the normal hES cells with embryonic TRF length from which EN13 was obtained.” 

“We observed variable but relatively long TRF lengths in hES cell lines of 16.1–21.1 kb, but markedly shorter TRF lengths ranging from 6.4 to 12.6 kb in all of the iPS cell lines studied.  In serially passaged iPS cell lines (iPS[IMR90]‑1, iPS[IMR90]‑4 and iPS[foreskin]‑1), TRF length progressively shortened during propagation.” — iPS cell lines consistently showed reduced levels of telomerase activity compared with hES cell lines.” On the other hand, the researchers discovered that one of six cloned lines of iPSC cells they generated expressed telomerase and that in that particular cell line telomeres got longer in successive cell generations until they got to be comparable to the lengths in hES cells. “In order to verify these results in an isogenic background, we generated six iPS cell clones from the hES‑derived cell line EN13. These iPS cell clones showed initial telomere lengths comparable to the parental EN13 cells, had telomerase activity, expressed embryonic stem cell markers and had a telomere-related transcriptome similar to hES cells.  Subsequent culture of five out of six lines generally showed telomere shortening to lengths similar to that observed in the widely distributed iPS lines. However, the clone EH3, with relatively high levels of telomerase activity, progressively increased TRF length over 60 days of serial culture back to that of the parental hES cell line. Conclusion: Prematurely aged (shortened) telomeres appears to be a common feature of iPS cells created by current pluripotency protocols. However, the spontaneous appearance of lines that express sufficient telomerase activity to extend telomere length may allow the reversal of developmental aging in human cells for use in regenerative medicine.” It is interesting that for mouse iPSCs the same thing is observed to happen.  The iPSCs start out with short telomeres like the mature cells that were reverted had, but they express telomerase and grow longer telomeres in succeeding cell-division generations.   See the 2009 publication Telomeres acquire embryonic stem cell characteristics in induced pluripotent stem cells . 

The 2010 publication Embryonic Stem Cells/Induced Pluripotent Stem Cells points out what can be important differences between hESCs and hiPSCs, probably because of the fact that the hiPSCs were, in fact, old cells with short telomeres.  “we demonstrate here that hiPSCs are capable of generating hemangioblasts/blast cells (BCs), endothelial cells and hematopoietic cells with phenotypic and morphological characteristics similar to those derived from hESCs, but with a dramatic decreased efficiency. Furthermore, in distinct contrast to the hESC derivatives, functional differences were observed in BCs derived from hiPSCs, including significantly increased apoptosis, severely limited growth and expansion capability, as well as a substantially decreased hematopoietic colony forming capability. After further differentiation into erythroid cells, >1000-fold difference in expansion capability was observed in hiPSC-BCs versus hESC-BCs.” 

What I get out of this is: 

·        Reversion of cells to hiPSC status in many cases results in cells that do not express telomerase and have short telomeres.  They are very different in these respects from hESCs.  Such cells may be approaching senescence despite their pluripotency, cannot reliably be depended on for such tasks as organ renewal, and cannot be used to close the loop in the stem cell supply chain(ref)(ref). 

·        A strain of iPSCs could express telomerase in which case the telomeres in succeeding generations could get longer.  How to reliably produce such strains remains unclear.  Telomerase can be exogenously applied in the process of generating iPSCs to provide them with longer initial telomeres but, without inherent capability to express telomerase, such iPSCs are apt to be of limited use. 

·        It appears that much more is to be learned before iPSCs with long replicative life spans can be reliably produced and used for regenerative purposes.  We need black-belt iPSC and telomerase researchers to put their heads together to figure out what can be done.

This blog entry reviews five very-recent clinical trials related to diabetes treatments, three that have failed and two that have succeeded.  I conclude by commenting on what I think are some underlying messages. 

FAILED DIABETES-RELATED CLINICAL TRIALS

I picked these items up from a March 14 New York Times story pointing to studies just published on March 14 in the New England Journal of Medicine, studies that have invalidated three favorite strategies for treating diabetics. As the article points out “An estimated 21 million Americans have Type 2 diabetes, the kind once known as adult-onset, and they are at enormous risk for heart disease. The only measures proved to reduce their chances — avoiding cigarettes and taking medication to lower bad cholesterol and blood pressure — still leave diabetics with a heart attack risk equivalent to that of a nondiabetic who has already had a heart attack.  —  So doctors began trying other strategies they hoped would help: getting blood pressure to a normal range; raising levels of good cholesterol and lowering levels of dangerous triglycerides; or modulating sharp upswings in blood sugar after a meal.”  In large-scale clinical trials, all three strategies failed.

Strategy 1: Reducing high blood pressure in diabetics will reduce incidence of heart attacks and heart attack deaths.

“Because cardiovascular risk in patients with diabetes is graded and continuous across the entire range of levels of systolic blood pressure, even at prehypertensive levels, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) recommended beginning drug treatment in patients with diabetes who have systolic blood pressures of 130 mm Hg or higher, with a treatment goal of reducing systolic blood pressure to below 130 mm Hg(ref).^1,2,3”

According to the March 14 2010 NEJM report Effects of Intensive Blood-Pressure Control in Type 2 Diabetes Mellitus  Background There is no evidence from randomized trials to support a strategy of lowering systolic blood pressure below 135 to 140 mm Hg in persons with type 2 diabetes mellitus. We investigated whether therapy targeting normal systolic pressure (i.e., <120 mm Hg) reduces major cardiovascular events in participants with type 2 diabetes at high risk for cardiovascular events. ^— Methods A total of 4733 participants with type 2 diabetes were randomly assigned to intensive therapy, targeting a systolic pressure of less than 120 mm Hg, or standard therapy, targeting a systolic pressure of less than 140 mm Hg. The primary composite outcome was nonfatal myocardial infarction, nonfatal stroke, or death from cardiovascular causes. The mean follow-up was 4.7 years.  ^— Results After 1 year, the mean systolic blood pressure was 119.3 mm Hg in the intensive-therapy group and 133.5 mm Hg in the standard-therapy group. The annual rate of the primary outcome was 1.87% in the intensive-therapy group and 2.09% in the standard-therapy group (hazard ratio with intensive therapy, 0.88; 95% confidence interval [CI], 0.73 to 1.06; P=0.20). The annual rates of death from any cause were 1.28% and 1.19% in the two groups, respectively (hazard ratio, 1.07; 95% CI 0.85 to 1.35; P=0.55). The annual rates of stroke, a prespecified secondary outcome, were 0.32% and 0.53% in the two groups, respectively (hazard ratio, 0.59; 95% CI, 0.39 to 0.89; P=0.01). Serious adverse events attributed to antihypertensive treatment occurred in 77 of the 2362 participants in the intensive-therapy group (3.3%) and 30 of the 2371 participants in the standard-therapy group (1.3%) (P<0.001).

Conclusions In patients with type 2 diabetes at high risk for cardiovascular events, targeting a systolic blood pressure of less than 120 mm Hg, as compared with less than 140 mm Hg, did not reduce the rate of a composite outcome of fatal and nonfatal major cardiovascular events. (ClinicalTrials.gov number, NCT00000620 [ClinicalTrials.gov] .)  

Strategy 1 is shot down.  In fact, the Times article points out that many of those taking the blood pressure reducing medication were worse off because of side effects and that “A second, less rigorous study, involving 6,400 patients with Type 2 diabetes and heart disease, asked whether getting systolic blood pressure lower than 130 was any better than getting it to 130 to 140. It found that patients actually were worse off: those with the lower blood pressure ended up with a 50 percent greater risk of strokes, heart attacks or deaths.”

Strategy 2: Raising levels of good cholesterol and lowering levels of dangerous triglyceride in patients with diabetes will reduce incidence of heart attacks and heart attack deaths.

Another March 14 NEJM report is Effects of Combination Lipid Therapy in Type 2 Diabetes Mellitus.  “Background: We investigated whether combination therapy with a statin plus a fibrate, as compared with statin monotherapy, would reduce the risk of cardiovascular disease in patients with type 2 diabetes mellitus who were at high risk for cardiovascular disease.  ^— Methods We randomly assigned 5518 patients with type 2 diabetes who were being treated with open-label simvastatin to receive either masked fenofibrate or placebo. The primary outcome was the first occurrence of nonfatal myocardial infarction, nonfatal stroke, or death from cardiovascular causes. The mean follow-up was 4.7 years.

“The hypothesis that we tested in ACCORD Lipid was that in high-risk patients with type 2 diabetes, combination treatment with a fibrate (both to raise HDL cholesterol levels and to lower triglyceride levels) and a statin (to reduce LDL cholesterol levels) would reduce the rate of cardiovascular events, as compared with treatment with a statin alone.”

“By the end of the study, the mean LDL cholesterol level fell from 100.0 to 81.1 mg per deciliter (2.59 to 2.10 mmol per liter) in the fenofibrate group and from 101.1 to 80.0 mg per deciliter (2.61 to 2.07 mmol per liter) in the placebo group (Figure 1, and Section 16 in Supplementary Appendix 1). Mean HDL cholesterol levels increased from 38.0 to 41.2 mg per deciliter (0.98 to 1.07 mmol per liter) in the fenofibrate group and from 38.2 to 40.5 mg per deciliter (0.99 to 1.05 mmol per liter) in the placebo group. Median plasma triglyceride levels decreased from 189.0 to 147.0 mg per deciliter (2.13 to 1.66 mmol per liter) in the fenofibrate group and from 186.2 to 170.0 mg per deciliter (2.10 to 1.92 mmol per liter) in the placebo group.” 

“Conclusions The combination of fenofibrate and simvastatin did not reduce the rate of fatal cardiovascular events, nonfatal myocardial infarction, or nonfatal stroke, as compared with simvastatin alone. These results do not support the routine use of combination therapy with fenofibrate and simvastatin to reduce cardiovascular risk in the majority of high-risk patients with type 2 diabetes. (ClinicalTrials.gov number, NCT00000620 [ClinicalTrials.gov] .)” 

Strategy 2 is shot down. 

Strategy 3: Modulating sharp upswings in blood sugar after a meal will reduce incidence of diabetes, heart attacks and heart attack deaths among persons with impaired glucose tolerance and established cardiovascular disease or cardiovascular risk factors.“

A final study investigated the popular hypothesis that rapid rises in blood glucose after a meal were dangerous and could lead to heart disease. Many doctors were giving drugs assuming the hypothesis was correct, Dr. Nathan said(ref).”A third March 14 2010 NEJM publication Effect of Nateglinide on the Incidence of Diabetes and Cardiovascular Events reports “Background The ability of short-acting insulin secretagogues to reduce the risk of diabetes or cardiovascular events in people with impaired glucose tolerance is unknown. ^— Methods In a double-blind, randomized clinical trial, we assigned 9306 participants with impaired glucose tolerance and either cardiovascular disease or cardiovascular risk factors to receive nateglinide (up to 60 mg three times daily) or placebo, in a 2-by-2 factorial design with valsartan or placebo, in addition to participation in a lifestyle modification program. We followed the participants for a median of 5.0 years for incident diabetes (and a median of 6.5 years for vital status). We evaluated the effect of nateglinide on the occurrence of three coprimary outcomes: the development of diabetes; a core cardiovascular outcome that was a composite of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure; and an extended cardiovascular outcome that was a composite of the individual components of the core composite cardiovascular outcome, hospitalization for unstable angina, or arterial revascularization.  ^— Results After adjustment for multiple testing, nateglinide, as compared with placebo, did not significantly reduce the cumulative incidence of diabetes (36% and 34%, respectively; hazard ratio, 1.07; 95% confidence interval [CI], 1.00 to 1.15; P=0.05), the core composite cardiovascular outcome (7.9% and 8.3%, respectively; hazard ratio, 0.94, 95% CI, 0.82 to 1.09; P=0.43), or the extended composite cardiovascular outcome (14.2% and 15.2%, respectively; hazard ratio, 0.93, 95% CI, 0.83 to 1.03; P=0.16). Nateglinide did, however, increase the risk of hypoglycemia.  ^—Conclusions Among persons with impaired glucose tolerance and established cardiovascular disease or cardiovascular risk factors, assignment to nateglinide for 5 years did not reduce the incidence of diabetes or the coprimary composite cardiovascular outcomes. (ClinicalTrials.gov number, NCT00097786 [ClinicalTrials.gov] .)

Strategy 3 is shot down.

SUCCESSFUL DIABETES-RELATED CLINICAL TRIALS

Not all the diabetes-related clinical trial results have been negative.  A Feb 11 2010 News Highlights report from Gen describes how “Roche Reports Positive Data from Five Phase III Trials of Type 2 Diabetes Therapy —  Roche says data from the first five Phase III trials with its once-weekly type 2 diabetes candidate taspoglutide showed that the GLP-1 analogue met its primary endpoints of reducing blood glucose levels. — “These Phase III studies have shown that treatment with once weekly taspoglutide leads to significantly improved blood glucose control, consistent weight loss, a minimal risk of hypoglycemia, and a manageable safety profile,” comments Hal Barron, Roche’s global head of product development. — The Phase III development program for taspoglutide includes eight studies that will enroll some 6,000 patients. Four of the studies have active comparators including exenatide, sitagliptin, insulin glargine, and pioglitazone.” 

A January 26 report in Gen indicates “Novo Nordisk’s Type 2 Diabetes Drug Green-Lighted by FDA — FDA sanctioned Novo Nordisk’s type 2 diabetes drug Victoza® (liraglutide) as a monotherapy in second-line treatment and in combination with other commonly prescribed oral diabetes therapeutics. U.S. approval comes less than a week after Japanese regulatory authorities gave Victoza the go-ahead. — U.S. approval of Victoza came with a Risk Evaluation and Mitigation Strategy consisting of a medication guide and a communication plan. Novo Nordisk aims to introduce the drug in the U.S. within weeks. — Victoza is a once-daily human GLP-1 (glucagon-like peptide-1) analogue and is given as an injection. “This is the first direct competition to the Byetta franchise,” according to Canaccord Adams life sciences analyst Adam Cutler. Amylin Pharmaceuticals’ Byetta and Victoza belong to the same family of drugs. “Byetta sales and prescription trends have remained flat, and we expect this news to further weaken them.” Byetta brought in $503.9 million through U.S. sales during the first three quarters of last year. ==Victoza is intended to help lower blood sugar levels along with diet, exercise, and other selected diabetes medicines. It is not recommended as initial therapy in patients who have not achieved adequate diabetes control on diet and exercise alone. –In five clinical trials involving more than 3,900 people, pancreatitis occurred more often in patients who took Victoza than in patients taking other antidiabetics, the FDA points out. The agency also advices that the therapy should be used with caution in people with a history of pancreatitis.”

COMMENTS

First, I acknowledge that these clinical trials have contributed to our incremental knowledge about what diabetes is and treatments that do and do not work.  Taspoglutide which has to be taken only once a week has the potential of becoming a blockbuster drug.  Exenatide, an existing drug in the same class, has to be taken twice daily.

Second, the clinical trial failures indicate how much we still are in an extremely expensive trial-and-error approach to treating diabetes, as I believe we are in for multiple other diseases.  Enormous amounts of money, effort and time have been poured into these clinical trials, each involving thousands of participants.  Taspoglutide alone has been scheduled for eight Phase III trials.  Ultimately these costs of hundreds of millions of dollars are reflected in the prices of approved drugs and contribute to the cost of health care.  Further, time required for the tests can keep needed drugs off the market for years.

Third, all the treatments mentioned relate to management of diabetic conditions or cardiovascular risk factors.  Such management is extremely important but lifestyle and dietary factors can be equally or even more important in preventing onset of diabetes as well as its management.  I wonder whether spending the amount of money required for these clinical trials instead on anti-obesity education might have resulted in a much greater overall positive impact.

Fourth, as time progresses, basic scientific approaches may obviate the necessity for such large-scale trial-and-error clinical trial approaches and allow smaller, faster and more focused clinical trials.  As more individual genomes are decoded and more and more diabetes whole-genome association studies are performed(ref)(ref), “one size fits all” therapies will give way to personalized ones.  (See the recent blog entry on Genome-wide association studies.) Emphasis will hopefully shift from management of diabetes to its prevention(ref).  Genomic knowledge may allow determining susceptibility of an individual to diabetes early in life and establishing a lifestyle program to assure that diabetes does not emerge in that person(ref)(ref)(ref). 

Once upon a time, an emphasis in medical treatment of people with polio was to have them live their lives in iron lung machines.  Then, basic scientific research allowed us virtually to wipe polio out.  It is time for us to do the same with Type 2 diabetes, and perhaps to let up on looking for better iron-lung type disease-management approaches.

Every once in a while I review a natural substance supplement.  This time its fucoidan, a complex sulfated polysaccharide (multi-sugar substance) found mainly in various species of brown seaweed.  Known for about 40 years for multiple health-giving biological activities, fucoidan has been the subject of hundreds of research studies.  Yet, my impression is that there is still much to be learned about this substance.  In this post I attempt to clarify what is known about fucoidan and what is still to be learned.

The species of brown seaweed containiong fucoidan include kombu, limu moui, bladderwrack, wakame, mozuku, and hijiki.  Also, variant forms of fucoidan have also been found in animal species, including the sea cucumber.  Seaweed containing fucoidan have traditionally been consumed in places like Okinawa,Hawaii andTonga, locations known for the health and longevity of their populations.  It is interesting that much of the research on fucoidan appears to have been done in Asia.  Of the hundreds of publications on fucoidan, I can cite only a small sample of representative ones here.

From a web page of the Sloan Kettering Memorial Cancer Center:

“Clinical Summary:   Fucoidan is a sulfated polysaccharide found in the cell walls of many species of Brown seaweed. Preliminary data show that fucoidan has antitumor and antiangiogenic ^{(2) (3) (4) (5) (6) (7)} effects in vitro. These effects are brought about by stimulating natural killer cells and by down regulating AP-I involved in cellular proliferation. Fucoidan also exhibited neuroprotective effects ^{(11) (12)}, but human data is lacking.   In other studies, fucoidan demonstrated anticoagulant ^{(8) (9)} and antithrombotic ⁽¹⁰⁾ activities, and can have additive effects when taken with anticoagulants.”

“Mechanism of Action:  Fucoidan has been shown to inhibit metastasis by preventing adhesion of tumor cells to the extracellular matrix. This is achieved by blocking the fibronectin cell-binding domain, necessary for formation of adhesion complexes ⁽⁴⁾. Fucoidan was also shown to induce apoptosis of human T-cell leukemia virus type I (HTLV-1) that causes Adult T-cell leukemia. It does so by inactivating NF-kB that regulates antiapoptotic proteins. It suppresses AP-I, a transcription factor involved in cellular proliferation and transformation ⁽³⁾. An vitro study showed that Fucoidan can suppress angiogenesis induced by Sarcoma 180 cells in mice ⁽⁵⁾. Fucoidan has immunomodulating effects and enhanced the activity of NK cells, which play a crucial role in mediating tumor cell death ⁽²⁾. The neuroprotective effects of fucoidan are attributed to its ability to suppress tumor necrosis factor-alpha (TNF-alpha)- and interferon-gamma (IFN-gamma)-induced NO production in C6 glioma cells ⁽¹¹⁾ and to its antioxidative effects ⁽¹²⁾.”

Fucoidan and cancers

The 2005 paper Fucoidan extracted from Cladosiphon okamuranus Tokida induces apoptosis of human T-cell leukemia virus type 1-infected T-cell lines and primary adult T-cell leukemia cells is a cell and mouse-level study.  “Further analysis showed that fucoidan inactivated NF-kappaB and activator protein-1 and inhibited NF-kappaB-inducible chemokine, C-C chemokine ligand 5 (regulated on activation, normal T expressed and secreted) production, and homotypic cell-cell adhesion of HTLV-1-infected T-cell lines. In vivo use of fucoidan resulted in partial inhibition of growth of tumors of an HTLV-1-infected T-cell line transplanted subcutaneously in severe combined immune deficient mice. Our results indicate that fucoidan is a potentially useful therapeutic agent for patients with ATL.”.

The 2009 paper Inhibitory effect of fucoidan on Huh7 hepatoma cells through downregulation of CXCL12 described yet-another cell-level study.   “The aim of this study is to assess whether fucoidan — exerts antitumor activity toward Huh7 hepatoma cells. According to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, fucoidan inhibited the growth of Huh7 cells and HepG2 cells in a dose-dependent manner, with a 50% inhibition of cell growth (IC50) of 2.0 and 4.0 mg/ml, respectively.”

The 2009 paper Apoptosis inducing activity of fucoidan in HCT-15 colon carcinoma cells describes a pre-clinical study on colon cancer cells.  “These findings provide evidence demonstrating that the pro-apoptotic effect of fucoidan is mediated through the activation of ERK, p38 and the blocking of the PI3K/Akt signal pathway in HCT-15 cells. These data support the hypothesis that fucoidan may have potential in colon cancer treatment.”

The 2009 paper Fucoidan induces apoptosis through activation of caspase-8 on human breast cancer MCF-7 cells describes another cell-level study. “ — we investigated the effect of fucoidan on the induction of apoptosis in human breast cancer MCF-7 cells. Our data demonstrated that fucoidan reduced the viable cell number of MCF-7 cells in a dose- and time-dependent manner. In contrast, fucoidan did not affect the viable cell number of normal human mammary epithelial cells. Results from the apoptosis assay demonstrated that fucoidan induced internucleosomal DNA fragmentation, chromatin condensation, activation of caspase-7, -8, and -9, and cleavage of poly(ADP ribose) polymerase.”  Also see Intracellular signaling in the induction of apoptosis in a human breast cancer cell line by water extract of Mekabu

The 2009 paper Fucoidan-Vitamin C complex suppresses tumor invasion through the basement membrane, with scarce injuries to normal or tumor cells, via decreases in oxidative stress and matrix metalloproteinases, describes yet-another cell level study, this time involving fucoidan in combination with vitamin C.  “Invasion of human fibrosarcoma cells HT-1080 through the basement membrane was repressed by Fucdn-VC-IB of non-cytotoxic concentrations without significant inhibition to human skin dermal fibroblasts DUMS-16 cells. Fucdn-VC-IB suppressed the invasiveness-related gelatinases MMP-2/9, and diminished reactive oxygen species inside the cytoplasm around the nucleus, in HT-1080 cells as shown by electrophoretic zymography and the redox indicator NBT assay, respectively. Thus Fucdn-VC-IB markedly exhibits antioxidant and MMP-suppressing activities and preferentially inhibited tumor invasion without cytotoxicity to normal cells, and is suggested as a potent tumor-invasion suppressor.”

The 2007 paper Antitumor and antimetastatic activity of fucoidan, a sulfated polysaccharide isolated from the Okhotsk Sea Fucus evanescens brown alga describes a mouse-based study.  “Antitumor and antimetastatic activities of fucoidan, a sulfated polysaccharide isolated from Fucus evanescens (brown alga in Okhotsk sea), was studied in C57Bl/6 mice with transplanted Lewis lung adenocarcinoma. Fucoidan after single and repeated administration in a dose of 10 mg/kg produced moderate antitumor and antimetastatic effects and potentiated the antimetastatic, but not antitumor activities of cyclophosphamide. Fucoidan in a dose of 25 mg/kg potentiated the toxic effect of cyclophosphamide.”

Fucoidan, neurogenesis and neurological diseases

A 2010 Japanese paper Proliferative effects on neural stem/progenitor cells of a sulfated polysaccharide purified from the sea cucumber Stichopus japonicus suggests the interesting result that fucoidan can promote neurogenesis from neural stem progenitor cells. “Our results showed that HS (haishen, a highly sulfated fucoidan) alone increased NSPC viability in a dose-dependent manner. Moreover, HS acted synergistically with fibroblast growth factor-2 (FGF-2) but not epidermal growth factor (EGF) to enhance the proliferation of NSPCs. Finally, HS did not induce apoptosis of NSPCs. Our findings suggest that HS can serve as an adjuvant for promoting the proliferation of NSPCs.”  Again, this is a cell-level study.

The 2009 publication Suppression of iNOS expression by fucoidan is mediated by regulation of p38 MAPK, JAK/STAT, AP-1 and IRF-1, and depends on up-regulation of scavenger receptor B1 expression in TNF-alpha- and IFN-gamma-stimulated C6 glioma cells is quite technical but interesting.  “In neurodegenerative disorders, activated glial cells overproduce nitric oxide (NO), which causes neurotoxicity. Inducible NO synthase (iNOS) is a potential therapeutic target in neurodegenerative diseases. Here, we examined the action of fucoidan, a high-molecular-weight sulfated polysaccharide, on tumor necrosis factor-alpha (TNF-alpha)- and interferon-gamma (IFN-gamma)-induced NO production in C6 glioma cells. Fucoidan suppressed TNF-alpha- and IFN-gamma-induced NO production and iNOS expression. In addition, fucoidan inhibited TNF-alpha- and IFN-gamma-induced AP-1, IRF-1, JAK/STAT and p38 mitogen-activated protein kinase (MAPK) activation and induced scavenger receptor B1 (SR-B1) expression. — The present results also suggest that fucoidan could be a potential therapeutic agent for treating inflammatory-related neuronal injury in neurological disorders.”

Fucoidan and Alzheimer’s disease

 

Fucoidan could conceivably play a role in the treatment of Alzheimer’s disease, as suggested by the paper Functional and physical interactions between Formyl-Peptide-Receptors and Scavenger Receptor MARCO and their involvement in Amyloid beta 1-42 (Abeta1-42)-induced signal transduction in Glial Cells.  “ — we have demonstrated a functional interaction between FPRL1 and scavenger receptors in fucoidan-mediated signalling by ERK1/2 phosphorylation and cAMP level measurement. In addition, co-immunoprecipitation data and fluorescence microscopy measurements revealed a physical interaction between FPR, FPRL1 and MARCO. These results suggest that FPRL1 plays a pivotal role for Abeta1-42-induced signal transduction in glial cells and the interaction with MARCO (which is promoted by fuciodan)could explain the broad ligand spectrum of formyl peptide receptors.” Again, this is a cell-level study.

The 2005publication Fucoidan inhibits cellular and neurotoxic effects of β-amyloid (Aβ) in rat cholinergic basal forebrain neurons reports on a cell-level study.  The publication states “Fucoidan also attenuated Aβ-induced down-regulation of phosphorylated protein kinase C. Aβ1−42-induced generation of reactive oxygen species was blocked by prior exposure of cultures to Fucoidan. Furthermore, Aβ activation of caspases 9 and 3, which are signaling pathways implicated in apoptotic cell death, is blocked by pretreatment of cultures with Fucoidan. These results show that Fucoidan is able to block Aβ-induced reduction in whole-cell currents in basal forebrain neurons and has neuroprotective effects against Aβ-induced neurotoxicity in basal forebrain neuronal cultures.”

Fucoidan and Parkinson’s disease

 

The 2009 publication Fucoidan protects against dopaminergic neuron death in vivo and in vitro concludes  “– we found that fucoidan inhibited MPTP-induced lipid peroxidation and reduction of antioxidant enzyme activity. In addition, pre-treatment with fucoidan significantly protected against MPP(+)-induced damage in MN9D cells. Taken together, these findings suggest that fucoidan has protective effect in MPTP-induced neurotoxicity in this model of Parkinson’s disease via its antioxidative activity.”

 

Fucoidan and herpes simplex

 

The 2008 study Defensive effects of a fucoidan from brown alga Undaria pinnatifida against herpes simplex virus infection reports “Fucoidan, — was previously shown to be a potent inhibitor of the in vitro replication of herpes simplex virus type 1 (HSV-1). HSV-1 is a member of herpes viruses that cause infections ranging from trivial mucosal ulcers to life-threatening disorders in immunocompromised hosts. — The production of neutralizing antibodies in the mice inoculated with HSV-1 was significantly promoted during the oral administration of the fucoidan for 3 weeks. These results suggested that oral intake of the fucoidan might take the protective effects through direct inhibition of viral replication and stimulation of both innate and adaptive immune defense functions.”  Being a mouse study, the results are a step closer to having clinical relevancy than the results of cell-level studies such as cited above. 

Clinical trials related to fucoidan 

·        A pilot clinical trial testing fucoidan as an oral anti-coagulant was reported last year Pilot clinical study to evaluate the anticoagulant activity of fucoidan.  The outcome was negative. “Thus, fucoidan in the form used in this study does not seem to have an oral anticoagulant activity, but it has a very strong in-vitro anticoagulant activity.”

 

·         A tiny and highly specialized clinical trial is reported in the publication Fucoidan ingestion increases the expression of CXCR4 on human CD34+ cells. The conlusion was “Oral fucoidan significantly amplified the CXCR4+ HPC (hematopoietic progenitor stem cells) population. The ability to mobilize HPC using sulfated polysaccharides and mobilize more HPC with high levels of CXCR4 could be clinically valuable.”·          

·        There is a Phase 1 clinical trial now in the recruiting stage Phase 1 Dosing Study of BAX 513 in Healthy Volunteers.  Bax 513 is a fucoidan extract of Laminaria japonica.  “A Phase 1 Study to Evaluate the Effects of BAX 513 on Hemostatic Parameters in Healthy Volunteers.”  This is possibly the initial clinical trial in a series of them sponsored by big pharma companies

 

My take on fucoidan

 

·        Based on cell-level and some mouse studies the substance appears to have possible therapeutic potential in many dimensions.  Fucoidan has only recently become the subject of clinical investigations, however.  So, despite the long-familiarity with the substance its utility as a human therapy remains largely unexplored.

·        As conventional drug-discovery approaches become less productive, fucoidan is one of the natural substances pharmaceutical companies are starting to investigate.  We may expect soon to see clinical trials of proprietary fucoidan compounds for specific disease indications.

·        There appears to be an active market for fucoidan supplements with many sellers(ref).  As of this moment, however, I am unclear whether or not fucoidan belongs in an anti-aging supplement regimen. 

I expect we will be hearing a lot more about fucoidan as time progresses

My recent blog posting New views of Alzheimer’s disease and new approaches to treating it describes recent research relating to the disease and new understanding of what creates it.  This week the Alzheimer’s Association has released a new report that describes the social consequence of the disease: 2010 Alzheimer’s Disease Facts and Figures.  I cover a few highlights from that report in this blog entry, relate the facts and figures to what is known about the cause of the devastating disease,  and offer an opinion of what we should do as a society about Alzheimer’s disease and senile dementia.

Facts and Figures

• About 16.2 million Americans are now deeply affected by Alzheimer’s, 5.3 million who have the disease and another 10.9 million whose lives are wrapped up in caring for those who have the disease.

“In 2009, an estimated 10.9 million family members and friends provided unpaid care for a person with Alzheimer’s disease or another dementia.”  About 94 % of unpaid caregivers are family members; about 60% are women and about 60% are aged over 50.  The quality of the lives of many of these unpaid caregivers is seriously impacted by their caregiver responsibilities. 40% of caregivers of Alzheimer’s disease patients report high emotional stress compared to 28% of caregivers of other older people. “Because Alzheimer’s and other dementias usually progress slowly, most caregivers spend many years in the caregiving role. At any point in time, 32 percent of family and other unpaid caregivers of people with Alzheimer’s and other dementias have been providing help for five years or longer, including 12 percent who have been providing care for 10 years or longer. An additional 43 percent have been providing care for one to four years, and 23 percent have provided care for less than a year.”  (Quotes here are from the report)

• The total current economic impact of the disease is $316 billion, $172 of which is for paid care of those having the disease and $144 billion is for the effort of unpaid caregivers.  (Note that these figures do not take into account another very large amount for lost economic productivity of those having the disease.)

According to the report, payments for health and long-term care services for people with Alzheimer’s will total $172 billion this year. Unpaid caregivers provided 12.5 billion hours of care in 2009, valued at $144 billion with care valued at $11.50 per hour.  It is pointed out that this is more than the federal government spends on Medicare and Medicaid combined for people with Alzheimer’s and other dementias.

• More than any other disease, Alzheimer’s and other dementias are signature diseases of old age. Death rates rise precipitously with age.

Death rate per 100,000Age                

                         2000                 2006

45–54            0.2                        0.2

55–64            2.0                        2.1

65–74            18.7                   20.2

75–84            139.6               175.6

85+                  667.7              848.3 

Other diseases of old age do not present such a steep rise in the death rate with increasing age.  “To put such age-related differences into perspective, for U.S. deaths in 2006, the differences in total mortality rates from all causes of death for those aged 65–74 and those aged 75–84 was 2.5-fold, and between the 75–84 age group and the 85 and older age group, 2.6-fold. For diseases of the heart, the differences were 2.8-fold and 3.2-fold, respectively.  For all cancers, the differences were 1.7-fold and 1.3-fold respectively. The corresponding differences for Alzheimer’s were 8.7-fold and 4.8-fold.  This is because Alzheimer’s is most likely caused by cell senescence of microglia, increasing cell senescence being a normal consequence of the aging process.  Getting Alzheimer’s is part of normal aging.  It is not necessarily caused by a bacterium or virus and does not necessarily require a gene defect although it could be triggered by such conditions.

·        There is currently no treatment for the disease 

“No treatment is available to slow or stop the deterioration of brain cells in Alzheimer’s disease. The U.S. Food and Drug Administration has approved five drugs that temporarily slow worsening of symptoms for about six to 12 months, on average, for about half of the individuals who take them.”  Puny results for expensive drugs is all the pharmaceutical industry has been able to provide at this point. 

·        While the risk of death due to other diseases continues to decrease with time, the risk of death due to Alzheimer’s disease is rapidly increasing. 

Between 3000 and 2006 causes of death % changes:

Alzheimer’s disease           +46.1%

Stroke                                    -18.2%

Prostate cancer                    -8.7%          

Heart disease                       -11.1%

HIV                                         -16.3%

The report projects 500,000 new cases of Alzheimer’s will be diagnosed this year. The report estimates that almost a million new cases of Alzheimer’s will be diagnosed annually by 2050.

• Medicare costs for Alzheimer’s patients are almost three times higher than for other older people and Medicaid costs are almost nine times higher.

“Hospital: In 2004, Medicare beneficiaries aged 65 and older with Alzheimer’s and other dementias were 3.1 times more likely than other Medicare beneficiaries in the same age group to have a hospital stay.  — Skilled nursing facility: In 2004, Medicare beneficiaries aged 65 and older with Alzheimer’s and other dementias were eight times more likely than other Medicare beneficiaries in the same age group to have a Medicare-covered stay in a skilled nursing facility.”

• The disease affects women more than men and blacks and Hispanics more than whites.
  • Blacks are roughly twice as likely to get the disease compared to whites.
  • Hispanics  are roughly 1.5 times as likely to get the disease compared to whites.
  • Women are more or less 1.7 times or more likely to get the disease then men, depending on the age group.
• Alzheimer disease patients are likely to have concurrent medical issues

Percentage withAlzheimer’s or OtherDementia and theCoexisting Condition       

Hypertension                                                    60%

Coronary heart disease                                  26%

Stroke—late effects                                         25%

Diabetes                                                             23%

Osteoporosis                                                     18%

Congestive heart failure                                16%

Chronic obstructive pulmonary disease     15%

Cancer                                                                 13%

Parkinson’s disease                                            8%

Data is for 2004 medicare beneficiaries aged 65 and older

What more can be done about Alzheimer’s disease?

I would like to see a few things shifted.

1.     I think it would be beneficial to stop viewing Alzheimer’s disease as yet another disease we are seeking to cure and start viewing AD as intrinsically wrapped up with aging, one of several aging processes that gets ahead of the other aging processes in AD patients.  The present find-a-specific-cure viewpoint has not worked and can’t work because AD is due to cell senescence of microglia. It is due to a process that is intrinsic to aging itself.  In fact, if we could delay all other age-related diseases, then AD would get virtually everybody by age 125.  In other words, curing AD and “curing aging” are likely to be part and parcel of the same thing.

2.     Major shifts in AD research are in order.  Efforts to find a chemical by trial-and-error that is a partial or entire cure, such as pharmaceutical companies have been pursuing for decades, are a modern form of alchemy rather than scientific research.  Any research that is going to move us forward has to look at the fundamental molecular biological and genetic-genomic processes involved. 

3.     I suspect that current research and clinical trials aimed at reducing or eliminating tau tangles and amyloid-beta plaques in AD patients(ref) may lead to therapies that slow the progress of AD but are unlikely to produce cures because they do not address the root cause of the disease.

4.     I think the research cited in the blog entry New views of Alzheimer’s disease and new approaches to treating it points its fingers at microglial cell senescence as a root cause for AD.  Additional research I have reviewed since writing that blog entry confirms this conclusion.  Therefore, any treatment that fundamentally addresses AD must address cell senescence and/or failure of cell replacement through stem cell differentiation.  If a treatment works to significantly delay or prevent AD it is likely to work to significantly delay or prevent many other diseases and processes of aging as well.  The answer may lie in a more effective form of telomerase activation(ref), in reversing epigenomic markers of aging such as DNA methylation at selected promoter sites(ref) or in manipulating the stem cell supply chain probably using induced pluripotent stem cells(ref) or embryonic stem cells(ref).  Perhaps activation of the BDNF gene could be involved(ref).  Those are the kinds of basic research that should be encouraged.

5.     Another shift in aging and Alzheimer’s research is that there should be lots more of it. The report says “for every $25,000 the government spends on care for people with Alzheimer’s and dementia, it spends only $100 for Alzheimer research.”  This is an order-of-magnitude too little.

6.     Finally it is important to reiterate that a number of approaches are available to ordinary people that can usually delay onset of Alzheimer’s disease, other forms of dementia and other diseases resulting from cell senescence.  These are the measures in the anti-aging firewalls in my treatise ANTI-AGING FIREWALLS THE SCIENCE AND TECHNOLOGY OF LONGEVITY.  Many of my blog entries are also relevant such as Warding off Alzheimer’s Disease and things in my diet and Seven Ps of health and longevity.  And a search of blog entries using the term dementia will turn up several additional relevant blog entries.

Vitamin D is much in the news nowadays.  Over the last 10 years it has become increasingly clear that vitamin D plays several important roles beyond those involved in bone health.  Vitamin D presence or absence is implicated in several disease processes including tuberculosis and cancer and an adequate level of vitamin D is required for immune system responsiveness.  A just-published research study reveals a critical way in which vitamin D is involved in the immune response.  This blog entry reviews a little background on vitamin D3, what is known about the vitamin D receptor (VDR) protein, the new research, and implications for health and longevity.

Vitamin D and the VDR

Vitamin D is mentioned several times in my treatise and is a central pillar of the combined anti-aging firewalls Supplement Regimen.    I have also discussed or mentioned it in many` blog posts.  The post Vitamin D – don’t fall for it  describes research on how vitamin D administration in nursing communities significantly reduces the number of falls and consequent hip fractures and other orthopedic injuries.  The blog post Klotho anti-aging gene in the news describes how “Klotho expression is also important for averting premature aging due to overexpression of Vitamin D,” citing a number of papers relevant to that topic.  And the post Hypervitaminosis D and premature aging indicates, among other topics, how mice with their VDR gene knocked out age prematurely.  “The publication Premature aging in vitamin D receptor mutant mice  (vitamin D receptor (VDR) knockout mice)  states “Overall, VDR KO mice showed several aging related phenotypes, including poorer survival, early alopecia, thickened skin, enlarged sebaceous glands and development of epidermal cysts.”  “Since the phenotype of aged VDR knockout mice is similar to mouse models with hypervitaminosis D(3), our study suggests that VDR genetic ablation promotes premature aging in mice, and that vitamin D(3) homeostasis regulates physiological aging.”

Vitamin D3 (1alpha,25-dihydroxyvitamin D) is the active form of vitamin D taken in supplements and is of concern in this post.  It functions as a hormone.  D3 is also known as calcitriol.  A growing body of research publications point to the health importance of D3 in numerous biological pathways that go beyond bone health.  I cite only two as examples.  According to the 2008 publication The noncalciotropic actions of vitamin D: recent clinical developments, “RECENT FINDINGS: 1,25-Dihydroxyvitamin D stimulates the innate immune system, facilitating the clearance of infections such as tuberculosis. Hypovitaminosis D has been associated with several autoimmune disorders, various malignancies, and cardiovascular risk factors in a number of recent epidemiologic reports. Based on these observational reports, vitamin D and its analogues are being evaluated for the prevention and treatment of a variety of conditions, with early findings showing mixed results. SUMMARY: The broad tissue distribution of the 25-hydroxyvitamin D 1alpha-hydroxylase enzyme and the vitamin D receptor establish a role for 1,25-dihydroxyvitamin D in the pathophysiology of various disease states and provide new therapeutic targets for vitamin D and its analogues.”

A 2007 publication Expanding role for vitamin D in chronic kidney disease: importance of blood 25-OH-D levels and extra-renal 1alpha-hydroxylase in the classical and nonclassical actions of 1alpha,25-dihydroxy vitamin D(3) reports “Recent advances in the understanding of vitamin D have revolutionized our view of this old nutritional factor and suggested that it has much wider effects on the body than ever believed before. In addition to its well-known effects on calcium/phosphate homeostasis, vitamin D, through its hormonal form, 1alpha,25-dihydroxyvitamin D(3) or calcitriol, is a cell differentiating factor and anti-proliferative agent with actions on a variety of tissues around the body (e.g., skin, muscle, immune system). By influencing gene expression in multiple tissues, calcitriol influences many physiological processes besides calcium/phosphate homeostasis including muscle and keratinocyte differentiation, insulin secretion, blood pressure regulation, and the immune response. The incidence of various diseases including epithelial cancers, multiple sclerosis, muscle weakness as well as bone-related disorders has been correlated with vitamin D deficiency/insufficiency and has led to a re-evaluation of recommended daily intakes both in the normal subject and CKD patient.”

Even back in the early 2000s it was clear that D3 was important for the functioning of the immune system, but how and why was unclear.  The 2004 publication Vitamin D status, 1,25-dihydroxyvitamin D3, and the immune system  reported “The active form of vitamin D, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], has been shown to inhibit the development of autoimmune diseases, including inflammatory bowel disease (IBD). Paradoxically, other immune system-mediated diseases (experimental asthma) and immunity to infectious organisms were unaffected by 1,25(OH)2D3 treatment. There are similar paradoxical effects of vitamin D deficiency on various immune system functions. Vitamin D and vitamin D receptor (VDR) deficiency resulted in accelerated IBD.

”The vitamin D3 receptor (VDR) gene generates a protein which is a transcription factor that is activated by the presence of D3. “The calcitriol receptor, also known as the vitamin D receptor (VDR) and also known as NR1I1 (nuclear receptor subfamily 1, group I, member 1), is a member of the nuclear receptor family of transcription factors.^[1] Upon activation by vitamin D, the VDR forms a heterodimer with the retinoid-X receptor and binds to hormone response elements on DNA resulting in expression or transrepression of specific geneproducts. In humans, the vitamin D receptor is encoded by the VDR gene.^[2]”  Exploration of the activities of VDR has been key to discovering the various roles of vitamin D3 in maintaining health.

Vitamin D3 in the immune response

The new 7 March 2010 publication Vitamin D controls T cell antigen receptor signaling and activation of human T cells reports an important finding – Presence of vitamin D3 in the bloodstream is required for T cells being activated and mounting an effective immune response.  As reported yesterday in Science Daily: “For T cells to detect and kill foreign pathogens such as clumps of bacteria or viruses, the cells must first be ‘triggered’ into action and ‘transform’ from inactive and harmless immune cells into killer cells that are primed to seek out and destroy all traces of a foreign pathogen. — The researchers found that the T cells rely on vitamin D in order to activate and they would remain dormant, ‘naïve’ to the possibility of threat if vitamin D is lacking in the blood.”  The sequence of events is “First when the naive T cell recognizes foreign invaders like bacteria or viruses with T cell receptor (TCR), it sends activating signals – to the vitamin D receptor gene. The VDR gene then starts producing DVR protein, which binds vitamin D in the T cell – and becomes activated. Then the vitamin D bound and activated DVR gets into the cell nucleus and activates the gene for PLC-gamma1 (5), which in turn produces PLC-gamma1 protein – and “the T cells can get started(ref).””

““Professor Carsten Geisler from the Department of International Health, Immunology and Microbiology explains that “when a T cell is exposed to a foreign pathogen, it extends a signaling device or ‘antenna’ known as a vitamin D receptor, with which it searches for vitamin D. This means that the T cell must have vitamin D or activation of the cell will cease. If the T cells cannot find enough vitamin D in the blood, they won’t even begin to mobilize. ” — T cells that are successfully activated transform into one of two types of immune cell. They either become killer cells that will attack and destroy all cells carrying traces of a foreign pathogen or they become helper cells that assist the immune system in acquiring “memory”. The helper cells send messages to the immune system, passing on knowledge about the pathogen so that the immune system can recognize and remember it at their next encounter. T cells form part of the adaptive immune system, which means that they function by teaching the immune system to recognize and adapt to constantly changing threats(ref).”

Implications

The new finding can explain a lot of the protective effects of D3,  ranging from reducing susceptibility to colds and flu(ref) to the role of D3 in chronic kidney disease(ref), reducing risk of asthma and respiratory infections(ref), its role in Graves’ hyperthyroidism(ref), how it fights placental infection(ref), bacterial vaginosis(ref) and pediatric infections(ref), and its protective effects against many other infections too numerous to catalog here.  And of course, vitamin D is essential for prevention and control of cardiovascular diseases(ref).  Unless someone is out in the sunlight for sustained periods every day, vitamin D3 supplementation is an absolute health necessity.

Please note the medical disclaimer for this blog.

A recent research report indicates that sestrin proteins can inhibit age-related pathologies in fruit flies and contribute to their longevity.  The genes and biological pathways involved exist also in humans.  This blog post reviews what the sestrin genes are, what the sestrin proteins do,  the new research describing the channels through which sestrins promote longevity, and how sestrins protect against cancer.

About sestrins

Sestrins are small protein molecules produced by three evolutionary conserved  genes in mammals, of which the sesn1 and sesn2 genes are activated by the p53 tumor-suppressor gene(ref)(ref).  Normally, when oxidative or other forms of stress activate p53, the target sesn1 and sesn2 genes are activated in turn.  These genes in turn activate AMP-dependent protein kinase (AMPK), which serves to inhibit  the Target of Rapamycin. E.g. inhibit  mTOR signaling(ref). Sestrins also provide a level of antioxidant defense in cells(ref). The 2007 publication p53 Target Genes Sestrin1 and Sestrin2 Connect Genotoxic Stress and mTOR Signaling provides ample detail for those of you who may wish to dig deeper.

Sestrins and longevity

The actions of sestrins are interesting from the viewpoint of longevity because for some time it has been known that inhibiton of mTOR signaling can lead to longer lifespans.  See the earlier blog post More mTOR links to aging theories “In my May 2009 blog post Longevity genes, mTOR and lifespan, I discussed the mTOR signaling pathway in mammals, its role in diseases, the relationship of mTOR to mitochondrial activity and how inhibiting mTOR could conceivably be a strategy for extending longevity.  In my Anti-Aging Firewalls treatise I subsequently added ABERRANT mTOR SIGNALLING as one of six additional candidate theories of aging to be considered.” See also the blog entry Viva mTOR! Caveat mTOR!.  Note that the m in mTOR stands for mammalian.“

The role of AMPK in regulating cellular energy charge places this enzyme at a central control point in maintaining energy homeostasis. More recent evidence has shown that AMPK activity can also be regulated by physiological stimuli, independent of the energy charge of the cell, including hormones and nutrients(ref).”  Exercise can increase AMPK activity as can taking certain polyphenol supplements like resveratrol(ref).  Another of the conditions that can activate AMPK is calorie restriction, a condition that slows down aging.  On the other hand, over-nutrition activates mTOR, accelerating aging.

The latest result appeared in the March 5 issue of Science: Sestrin as a Feedback Inhibitor of TOR That Prevents Age-Related Pathologies.  “We show that the abundance of Drosophila sestrin (dSesn) is increased upon chronic TOR activation through accumulation of reactive oxygen species that cause activation of c-Jun amino-terminal kinase and transcription factor Forkhead box O (FoxO).  Loss of dSesn resulted in age-associated pathologies including triglyceride accumulation, mitochondrial dysfunction, muscle degeneration, and cardiac malfunction, which were prevented by pharmacological activation of AMPK or inhibition of TOR. Hence, dSesn appears to be a negative feedback regulator of TOR that integrates metabolic and stress inputs and prevents pathologies caused by chronic TOR activation that may result from diminished autophagic clearance of damaged mitochondria, protein aggregates, or lipids.”  In other words, if TOR gets ramped up, in the absence of genetic damage it turns on sestrin which ramps TOR down again before TOR activity creates major damage.

According to a Science Daily article about this latest research, “They also showed that Sestrin, whose structure and biochemical function are conserved between flies and humans, is needed for regulation of a signaling pathway that is the central controller of aging and metabolism. – The new study took advantage of the finding that the fruit fly Drosophila, whose AMPK-TOR signaling pathway functions in the same manner as its mammalian equivalent, contains a single Sestrin gene. Using a variety of genetic techniques, first author Jun Hee Lee inactivated the Sestrin gene of Drosophila and found that although Sestrin-deficient flies do not exhibit any developmental abnormalities, they suffer from under-activation of AMPK and over-activation of TOR — confirming that Sestrin is needed for keeping this pathway in check. Most importantly, the biochemical imbalance incurred by loss of Sestrin expression resulted in several age-related pathologies. — “Strikingly, the pathologies caused by the Sestrin deficiency included accumulation of triglycerides, cardiac arrhythmia and muscle degeneration that occurred in rather young flies,” said Karin. “These pathologies are amazingly similar to the major disorders of overweight, heart failure and muscle loss that accompany aging in humans.” — Lee and colleagues at UC San Diego and the Sanford-Burnham Institute in La Jolla, California, went on to demonstrate that feeding flies with drugs that either activate AMPK or inhibit TOR conferred protection against most of these early aging, degenerative symptoms. The researchers also found that over-activation of TOR is likely to accelerate aging of heart and skeletal muscles by disrupting an important “quality control” process called autophagy. Autophagy allows cells to rid themselves of and replace damaged mitochondria, the little power plants that provide all cells, especially muscles, with energy. However, when mitochondria get old, they produce high concentrations of reactive oxygen species (ROS), or free radicals, that can lead to tissue damage.”

I have previously discussed how an effective antiaging intervention might be inhibition of mTOR.  The new research goes on to say how this might be accomplished through activation of sestrins. 

Sestrins and cancer

In many cancers, oncogenic mutations in RAS genes result in inactivation of p53 genes and resulting failure of activation of sestrin genes which results in increased  ROS (reactive oxygen species) levels and further oncogenic mutations.  This scenario is depicted in the 2007 paper Repression of Sestrin Family Genes Contributes to Oncogenic Ras-Induced Reactive Oxygen Species Up-regulation and Genetic Instability.  “Oncogenic mutations within RAS genes and inactivation of p53 are the most common events in cancer. Earlier, we reported that activated Ras contributes to chromosome instability, especially in p53-deficient cells. — Introduction of oncogenic RAS resulted in repression of transcription from sestrin family genes SESN1 and SESN3, which encode antioxidant modulators of peroxiredoxins. Inhibition of mRNAs from these genes in control cells by RNA interference substantially increased ROS levels and mutagenesis. — Thus, changes in expression of sestrins can represent an important determinant of genetic instability in neoplastic cells showing simultaneous dysfunctions of Ras and p53.”

BDNF stands for brain-derived neurotrophic factor, the protein generated by the BDNF gene, a substance that has been drawing a lot of attention recently in neuropsychiatric research circles.  I review some basic facts about BDNF here, recent research on how BDNF relates to personality, mental balance, and aging and, finally, current research on how BDNF expression is conditioned by epigenomic imprints.

About BDNF

“BDNF acts on certain neurons of the central nervous system and the peripheral nervous system, helping to support the survival of existing neurons, and encourage the growth and differentiation of new neurons and synapses.^[4][5] In the brain, it is active in the hippocampus, cortex, and basal forebrain—areas vital to learning, memory, and higher thinking.^[6] BDNF itself is important for long-term memory(ref).^[7] ”  BDNF is an important neurotrophic, meaning that it plays an important role in neurogenesis, the important process in parts of the brain of neural stem cells differentiating into neurons. “Neurotrophins are a family of proteins that induce the survival,^[1] development and function^[2] of neurons. — Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor found originally in the brain, but also found in the periphery. More specifically, it is a protein which has activity on certain neurons of the central nervous system and the peripheral nervous system; it helps to support the survival of existing neurons, and encourage the growth and differentiation of new neurons and synapses through axonal and dendritic sprouting. In the brain, it is active in the hippocampus, cortex, cerebellum, and basal forebrain—areas vital to learning, memory, and higher thinking. BDNF was the second neurotrophic factor to be characterized, after NGF and before neurotrophin-3. — Despite its name, BDNF is actually found in a range of tissue and cell types, not just the brain. Expression can be seen in the retina, the CNS, motor neurons, the kidneys, and the prostate(ref).”

BDNF and mental balance

According to the December 30 2009 paper BDNF Val66Met is Associated with Introversion and Interacts with 5-HTTLPR to Influence Neuroticism. “Brain-derived neurotrophic factor (BDNF) regulates synaptic plasticity and neurotransmission, and has been linked to neuroticism, a major risk factor for psychiatric disorders. A recent genome-wide association (GWA) scan, however, found the BDNF Val66Met polymorphism (rs6265) associated with extraversion but not with neuroticism. — ). Consistent with GWA results, we found that BDNF Met carriers were more introverted. — Our findings support the association between the BDNF Met variant and introversion and suggest that BDNF interacts with the serotonin transporter gene to influence neuroticism.” 

Also, aberrant BDNF is implicated in memory loss, anxiety and schizophrenia. Again, the culprit gene variant seems to be Val66met.  According to the 2008 publication Impact of genetic variant BDNF (Val66Met) on brain structure and function, “A common single-nucleotide polymorphism in the human brain-derived neurotrophic factor (BDNF) gene, a methionine (Met) substitution for valine (Val) at codon 66 (Val66Met) — A genetic variant BDNF may thus play a key role in genetic predispositions to anxiety and depressive disorders.”   Another relevant 2008 research publication is Meta-Analysis of the Brain-Derived Neurotrophic Factor (BDNF} Val66Met Polymorphism in Anxiety Disorders and Anxiety-Related Personality Traits.

Research study after research study have pointed to the importance of healthy expression of BDNF for long term memory including BDNF: A Key Regulator for Protein-synthesis Dependent LTP and Long-term Memory? and Regulation of late-phase LTP and long-term memory in normal and aging hippocampus: role of secreted proteins tPA and BDNF.

The association of BDNF VAL66Met with mental issues has been known for several years now.  According to the 2005 publication Association of a functional BDNF polymorphism and anxiety-related personality traits “Converging lines of evidence point to brain-derived neurotrophic factor (BDNF) as a factor in the pathophysiology of depression. Recently, it was shown that the Val allele of the BDNF Val66Met substitution polymorphism showed a significant association with higher mean neuroticism scores of the NEO-Five Factor Inventory (NEO-FFI) in healthy subjects, and previous studies suggested the Val allele to be increased in bipolar disorder families. — Our findings support the hypothesis that anxiety- and depression-related personality traits are associated with the BDNF polymorphism although the explained variance is low.”

Going back even a bit further, according to a 2003 NIMH research press release “NIH scientists have shown that a common gene variant influences memory for events in humans by altering a growth factor in the brain’s memory hub. On average, people with a particular version of the gene that codes for brain derived neurotrophic factor (BDNF) performed worse on tests of episodic memory—tasks like recalling what happened yesterday. They also showed differences in activation of the hippocampus, a brain area known to mediate memory, and signs of decreased neuronal health and interconnections. These effects are likely traceable to limited movement and secretion of BDNF within cells, according to the study, which reveals how a gene affects the normal range of human memory, and confirms that BDNF affects human hippocampal function much as it does animals'(ref).” 

The BDNF dementia and aging connection

Expression of BDNF is implicated in aging.  The 2008 study report Genetic contributions to age-related decline in executive function: a 10-year longitudinal study of COMT and BDNF polymorphisms says “Our results argue that — the Val/Val polymorphism for BDNF may promote faster rates of cognitive decay in old age. These results are discussed in relation to the role of BDNF in senescence and the transforming impact of the Met allele on cognitive function in old age.”

In fact expression of BDNF is implicated in anti-aging.   According to a news item published yesterday “UC Irvine neurobiologists are providing the first visual evidence that learning promotes brain health – and, therefore, that mental stimulation could limit the debilitating effects of aging on memory and the mind. Using a novel visualization technique they devised to study memory, a research team led by Lulu Chen and Christine Gall found that everyday forms of learning animate neuron receptors that help keep brain cells functioning at optimum levels. — These receptors are activated by a protein called brain-derived neurotrophic factor, which facilitates the growth and differentiation of the connections, or synapses, responsible for communication among neurons. BDNF is key in the formation of memories.” — “The findings confirm a critical relationship between learning and brain growth and point to ways we can amplify that relationship through possible future treatments,” says Chen, a graduate researcher in anatomy & neurobiology.”  I have reported previously in this blog on the importance of mental exercise and learning for prevention of dementia and longevity.  See the blog posts Mental exercise and dementia in the news again and Brain fitness, Google and comprehending longevity.  The new finding highlights the key role of BDNF expression in the process. 

I mentioned research on the use of neural stem cells as a source of BDNF in the blog entry Human embryonic stem cells and Alzheimer’s disease quoting the 2009 research report Neural stem cells improve cognition via BDNF in a transgenic model of Alzheimer disease. “Additionally, the improvement in memory and the increase in synaptic density observed after injection of neural stem cells were found to be mediated, at least in part, by the neurotrophic factor BDNF, which is secreted from the transplanted cells. GRNOPC1 has been found to secrete BDNF as well as other neurotrophic factors(ref).”  “Taken together, our findings demonstrate that neural stem cells can ameliorate complex behavioral deficits associated with widespread Alzheimer disease pathology via BDNF(ref).”

The BDNF epigenetics connection – DNA methylation and chromatin remodeling

Recent studies have gone beyond looking at the Val66Met polymorphism to identifying another reason for unwanted downregulation of BDNF expression – BDNF gene promoter methylation.  The 2010 paper Increased BDNF Promoter Methylation in the Wernicke Area of Suicide Subjects points to downregulation of BDNF activity due to DNA methylation being observed in suicide subjects.  The paper reports: Context  Brain-derived neurotrophic factor (BDNF) plays a pivotal role in the pathophysiology of suicidal behavior and BDNF levels are decreased in the brain and plasma of suicide subjects. So far, the mechanisms leading to downregulation of BDNF expression are poorly understood.  Objectives  To test the hypothesis that alterations of DNA methylation could be involved in the dysregulation of BDNF gene expression in the brain of suicide subjects.  Design  Three independent quantitative methylation techniques were performed on postmortem samples of brain tissue. BDNF messenger RNA levels were determined by quantitative real-time polymerase chain reaction. ^—. Main Outcome Measures  The DNA methylation degree at BDNF promoter IV and the genome-wide DNA methylation levels in the brain’s Wernicke area. Results  Postmortem brain samples from suicide subjects showed a statistically significant increase of DNA methylation at specific CpG sites in BDNF promoter/exon IV compared with nonsuicide control subjects (P < .001). —  Higher methylation degree corresponded to lower BDNF messenger RNA levels.  Conclusions  BDNF promoter/exon IV is frequently hypermethylated in the Wernicke area of the postmortem brain of suicide subjects irrespective of genome-wide methylation levels, indicating that a gene-specific increase in DNA methylation could cause or contribute to the downregulation of BDNF expression in suicide subjects. The reported data reveal a novel link between epigenetic alteration in the brain and suicidal behavior.”  It is tempting to hypothesize that BDNF methylation is a causal factor in suicides but the paper does not go that far.

The 2008 paper Epigenetic regulation of BDNF gene transcription in the consolidation of fear memory reports: Long-term memory formation requires selective changes in gene expression. Here, we determined the contribution of chromatin remodeling to learning-induced changes in brain-derived neurotrophic factor (bdnf) gene expression in the adult hippocampus. Contextual fear learning induced differential regulation of exon-specific bdnf mRNAs (I, IV, VI, IX) that was associated with changes in bdnf DNA methylation and altered local chromatin structure. — altered DNA methylation is sufficient to drive differential bdnf transcript regulation in the hippocampus — .  These results suggest epigenetic modification of the bdnf gene as a mechanism for isoform-specific gene readout during memory consolidation.”

Going back a bit earlier there was the 2005 paper Regional expression of brain derived neurotrophic factor (BDNF) is correlated with dynamic patterns of promoter methylation in the developing mouse forebrain. “These studies demonstrate that DNA methylation of this regulatory region may be an important mechanism controlling differential expression of BDNF during forebrain development.”

Early-life experiences or experiences of parents or grandparents can create changes in BDNF DNA methylation which affect learning, attitude or mental stability, as pointed out in the 2009 publication Lasting Epigenetic Influence of Early-Life Adversity on the BDNF Gene.  “Background: Childhood maltreatment and early trauma leave lasting imprints on neural mechanisms of cognition and emotion. With a rat model of infant maltreatment by a caregiver, we investigated whether early-life adversity leaves lasting epigenetic marks at the brain-derived neurotrophic factor (BDNF) gene in the central nervous system.  Methods: During the first postnatal week, we exposed infant rats to stressed caretakers that predominately displayed abusive behaviors. We then assessed DNA methylation patterns and gene expression throughout the life span as well as DNA methylation patterns in the next generation of infants.  Results: Early maltreatment produced persisting changes in methylation of BDNF DNA that caused altered BDNF gene expression in the adult prefrontal cortex. Furthermore, we observed altered BDNF DNA methylation in offspring of females that had previously experienced the maltreatment regimen.  Conclusions: These results highlight an epigenetic molecular mechanism potentially underlying lifelong and transgenerational perpetuation of changes in gene expression and behavior incited by early abuse and neglect.”

Putting it together

There are many more relevant BDNF literature citations out there, but these are sufficient to make certain key points:

·        Healthy BDNF gene expression is important for mental health, learning, memory, and preservation of cognitive capability with aging

·        One thing that can get in the way of healthy BDNF gene expression is the Val66Met polymorphism in the BDNF gene, a genetic condition.

·        Another thing that can get in the way of healthy BDNF gene expression is gene methylation, a type of epigenetic modification that can be induced by experience and that is possibly inheritable.  We have all known that early experience shapes the character.  We now know that one way that shaping takes place is molecularly via methylation of the BDNF gene.

·        Certain stem cells like those in Geron’s proprietary hESC-based GRNOPC1 line secrete BDNF and offer one means for introducing BDNF expression into tissues.

New research suggests that the answer to the question is quite possibly.  This is a rather technial subject and I will get into it in stages.  Finally, I speculate a little on the possible importance of the new research.

Repair mechanisims for double-strand breaks in DNA

In the course of a normal good day you may have a million or more events of DNA damage occur in your body.  If you are exposed to ionizing radiation or any substance that creates large numbers of free radicals or if you have certain disease processes like Alzheimer’s going on, the number of DNA damage events could be many times higher.  The kinds of DNA damage can be of multiple types(ref).  In this blog entry I am concerned with one particular important kind, double-strand breaks (DSBs), breaks that can occur naturally in cell differentiation or that are created by radiation and certain chemicals.   “The current view is that most spontaneous chromosomal rearrangements result from DSBs created mainly during DNA replication as a result of broken, stalled or collapsed replication forks(ref).”  

Because these breaks completely threaten genomic integrity, evolution has provided us with a number of sophisticated approaches for automatic DNA repair.  See Dancing on damaged chromatin: functions of ATM and the RAD50/MRE11/NBS1 complex in cellular responses to DNA damage.  “In order to preserve and protect genetic information, eukaryotic cells have developed a signaling or communications network to help the cell respond to DNA damage, and ATM and NBS1 are key players in this network. ATM is a protein kinase which is activated immediately after a DNA double strand break (DSB) is formed, and the resulting signal cascade generated in response to cellular DSBs is regulated by post-translational protein modifications such as phosphorylation and acetylation. In addition, to ensure the efficient functioning of DNA repair and cell cycle checkpoints, the highly ordered structure of eukaryotic chromatin must be appropriately altered to permit access of repair-related factors to DNA. These alterations are termed chromatin remodeling.”

Failure to repair double-strand DNA breaks or faulty repairs can have serious consequences.  As pointed out in the review publication Misrepair of radiation-induced DNA double-strand breaks and its relevance for tumorigenesis and cancer treatment:  “The faithful repair of DNA double-strand breaks (DSBs) is probably one of the most critical tasks for a cell in order to maintain its genomic integrity since these lesions may lead to chromosome breaks or rearrangements, mutations, cell death or cancer. DSBs can arise spontaneously during normal cellular DNA metabolism or may be induced by exogenous agents such as ionizing radiation. To overcome the danger that emanates from these lesions, eukaryotic cells have evolved specific pathways for processing DSBs. —  ”  Moreover, it is thought that an impaired capacity to repair double-strand breaks can lead to chromosome Instability (CIN) “ — a genome phenotype that involves changes in chromosome number or structure, and accounts for most malignancies(ref).”

There are two general repair pathways for double strand breaks, homologous recombination (HR) and non-homologous end joining (NHEJ). “Defects in either repair pathway result in high frequencies of genomic instability[4]. The HR pathway utilizes a homologous sequence to faithfully restore the DNA continuity at the DSB[5]. In contrast, NHEJ is a mechanism able to join DNA ends with no or minimal homology [6] (ref).”  “Non-homologous DNA end-joining (NHEJ)–the main pathway for repairing double-stranded DNA breaks–functions throughout the cell cycle to repair such lesions. Defects in NHEJ result in marked sensitivity to ionizing radiation and ablation of lymphocytes, which rely on NHEJ to complete the rearrangement of antigen-receptor genes. NHEJ is typically imprecise, a characteristic that is useful for immune diversification in lymphocytes, but which might also contribute to some of the genetic changes that underlie cancer and ageing(ref).”

The DNA repair pathways are complex but one gene/protein important both to faithful cell division and DNA repair appears to be Mms22, studied originally in budding yeast strains(ref)(ref). 

Roles of proteasomes in repairing double-strand DNA breaks

I found the new February 2010 publication Proteasome Nuclear Activity Affects Chromosome Stability by Controlling the Turnover of Mms22, a Protein Important for DNA Repair to be difficult to decipher at first.  So, I need to proceed slowly here.   Proteasomes are tiny protein recycling factories that live in cells, either in the cytoplasm or in the nucleus.  Actually they are sizeable protein complexes shaped like drums that breakup unneeded proteins (ones that are damaged, misfolded or used for short-term purposes as part of cell maintenance) using a chemical process called proteolysis.  “The degradation process yields peptides of about seven to eight amino acids long, which can then be further degraded into amino acids and used in synthesizing new proteins.^[2] Proteins are tagged for degradation with a considerably small protein called ubiquitin.  — The proteasomal degradation pathway is essential for many cellular processes, including the cell cycle, the regulation of gene expression, and responses to oxidative stress(ref).” 

For a long time is was thought that  DNA duplication and repair had nothing to do with the proteasomes, nothing anymore than an effective pressure cooker has to do with a garbage dispose-all.  The new research says “not so.”  In fact, DNA repair might not be completed because of defects in proteasome machinery. 

The new publication cites impressive research indicating that what goes on when a double-strand DNA break occurs includes 1.  Mms22 gets attracted to the double break site where it does its repair job.  2.  In the process Mms22 also gets highly ubiquinated, e.g. several morsels of ubiquitin are attached to it and thus it becomes a target for proteasomal degradation, 3.  Certain proteasomes (“The 26S proteasome comprises the 20S core particle (CP) and the 19S regulatory particle (RP), which represent the base and lid substructures, respectively(ref).”) are also attracted to the DNA break site, probably by accumulated ubiquinated Mms22, where they capture and set out to degrade the Mms22.  4.  If degradation is successful the DNA repair is completed, and 5.  If degradation is not successful the DNA break repair is not completed and the cell goes into prolonged cell-cycle arrest. 

“Indeed, we show that DNA damage results in Mms22 recruitment to the chromatin bound fraction –. Importantly, our results also show that recruitment of Mms22 to chromatin is not sufficient for the normal course of DNA repair, and that an essential step is a proteasome-mediated degradation of Mms22. These results thus identify for the first time a proteasome target that links proteasomal nuclear activity and DNA double strand break repair(ref).”  Also, “In this regard, proteasome inhibition in combination with DNA damage probably results in the accumulation of many proteins besides Mms22, which altogether may lead to the impaired recovery from the cell cycle arrest(ref).”The authors of the paper put it this way: “DNA damage results in a SCFrtt101 E3 ubiquitin ligase-dependent accumulation of the ubiquitinated form of Mms22 on chromatin that, as suggested above, plays a role in dealing with DNA damage. Subsequent degradation of ubiquitinated Mms22 by the proteasome is an important step in completion of the DNA repair process. Once Mms22 executes its function in DNA repair it becomes a target for degradation by the UPS (ubiquitin proteasome system), and is removed from chromatin.  Failure to degrade Mms22 results in impaired DNA repair and prolonged cell cycle arrest(ref).”

The authors point the finger for failure in double strand repair (and consequently for chromosome instability and carcinogenesis) to defects in the proteasomes: “In our current work, we show that mutations in the proteasome subunits rpn5ΔC and pup2, which cause nuclear mislocalization, are associated with impaired DSB (double-strand break) repair. All other proteasomal Ts mutants tested were sensitive to drugs inducing DSBs, implying that the proteolytic activity of the proteasome is required for DNA repair(ref).”  As mentioned, the mutations can cause the proteasomes of concern to locate outside of the cell nucleus where they normally reside making them unavailable to ubiquinated Mms22.

The research work described was done using strains of yeast (Saccharomyces cerevisiae) but is thought to be applicable to humans because of orthologs between human and yeast genes(ref)(ref).   

What I take away from this research is:

·        What we have here is another case of what was thought to be a well-understood cell component (a proteasome) showing up with a brand new function and importance. 

 ·        It provides another chunk of understand about important cell processes, another piece of the giant jigsaw puzzle that will eventually make clear to us what aging is and what we can do about it.  See my blog post The longevity jigsaw puzzle.

·        With each new piece of the puzzle, it seems that more questions are raised than are answered.  In the case of the research described above some of the questions are: Do these results largely based on yeast studies completely carry over to apply to humans?   If so, what can be done about defects in the genes for the proteasome subunits rpn5ΔC and pup2 to help prevent cancers?  Do proteasomes play a similar role with other DNA repair genes besides Mms22? What other interventions might be suggested by this work to improve efficiency of repair of double-strand DNA breaks?

·        There is a lot more interesting research related to DNA repair beyond the thread covered here and I will probably come back to that topic again before too long. 

This blog post is philosophical rather than scientific in its thrust, having to do with what successful aging consists of, including successful passing away.  Aging offers certain benefits – as long as you don’t age so much that you get sick.  A Google search on “joy of aging” reveals 616,000 entries ranging from inspirational stories, social groups, cartoons, jokes, poems and personal stories.  I share a few of those items here and what I think they are ultimately about.

The Google Joy of aging citations include lots of blog entries like this one, and this one,  often offering personal narratives on aging.  Many sites besides the religious ones offer inspirational advice, like the Twelve Secrets to Anti-Aging — e-book by Lynn A. Anderson, Ph.D., N.D. and this site.   

Underneath all the verbiage and positive thoughts about growing old, there is another theme, one of ravages and sicknesses of old age and sadness over loss of functionality. Growing old and Saging may be noble but it is no fun if you are undergoing  a leg amputation due to diabetes or your hair is falling out and you can’t hold food down because of chemotherapy, or when you are out with friends and have to empty your colostomy bag.    A number of videos offer songs and jokes old people tell on each other like this one. The words of the song at the end of the video tell this bittersweet message, sung to the tune of Camptown Racetrack. 

Grandma’s got a brand new hip, Do dah, do dah, She has collagen for a lip, Oh do dah, do dah day,G rowing old is fun, It sure beats staying young. I can’t find my IRA, Oh, do dah day.Grandpa had his knees replaced, Do dah, do dah, He has wrinkles for a face, Oh, do dah day.Growing old is fun, It sure beats staying young. I can’t remember yesterday, Oh, do dah day. I’ll tell you sumptin that’s even worse I don’t remember the first verse, Oh, do dah day Do dah, do dah, Growing old is fun,  It sure beats staying young.

This bittersweet theme runs deep in the “Joy of aging” Google citations.  From a Christian Bible site, “One story my wife and I both enjoy is about an elderly couple who was driving out to meet friends for a social evening. She says to him, “Honey, you try to remember where we’re going, and I’ll try to remember who we are.”  “My wild oats have turned into prunes and oat bran.” And nowhere are the ravages of old age more vividly portrayed than in the thousands of cartoons and jokes about old people kicking around the Internet(ref)(ref)(ref)(ref).  A lot of these are quite clever.  Advantages of growing old include(ref): ·         “Your eyes won’t get much worse,  ·          Your investment in health insurance is finally beginning to pay off, ·          Kidnappers are not very interested in you, and ·         In a hostage situation you are likely to be released first.” So, there is both a joy and sadness to aging.  Here are some of my own thoughts:

• I have not thought much about immortality: the idea of “live long enough and you can live forever” which contemplates a future time when a human life might be continued in an “immortal” machine environment.  I see that idea as more of a fantasy than as possible reality for the next fifty years at least and will think about it at a later time if and as it shows any hope of becoming real.  For me right now, radical life extension means living for a few hundred years in our original bodies.  And that is a huge reach in itself.
• Therefore, life extension, the thrust of this blog, will not get rid of aging, at least not very soon.  It hopefully will postpone aging for a goodly amount but the grim reaper is still going to get all of us. 
• The longer the life, the more the joys of life can be amplified.  I will love to play Monopoly and have funfull intellectual discussions with my great-great grandchildren, to keep expanding my wisdom and its impact on the world, and perhaps even to see a better more-responsible world order.
• While some sickness may be inevitable towards the end of life the impact of increasing longevity should be in an increase of the ratio of good healthy years to sick old years.  So, in the context of a good long healthy life, the sick unhealthy part at the end becomes less important. 
• The ideal outcome of life extension would be adding a lot of good healthy years until death comes quickly without a lot of debilitating sickness – the “One-hoss shay” idea from the poem with that name by Oliver Wendell Holmes.   The initial and final stanzas are:

“A Logical Story

Have you heard of the wonderful one-horse shay,
That was built in such a logical way
It ran a hundred years to a day,
And then, of a sudden, it–ah but stay,
I’ll tell you what happened without delay,
Scaring the parson into fits,
Frightening people out of their wits,
Have you ever heard of that, I say?Seventeen hundred and fifty-five,
Georgius Secundus was then alive,
Snuffy old drone from the German hive.
That was the year when Lisbon-town
Saw the earth open and gulp her down
And Braddock’s army was done so brown,
Left without a scalp to its crown.
It was on the terrible Earthquake-day
That the Deacon finished the one-hoss shay.Now in building of chaises, I tell you what,
There is always somewhere a weakest spot, –
In hub, tire, felloe, in spring or thill,
In panel, or crossbar, or floor, or sill,
In screw, bolt, thoroughbrace,–lurking still,
Find it somewhere you must and will,–
Above or below, or within or without,–
And that’s the reason, beyond a doubt,
That a chaise breaks down, but doesn’t wear out.

But the Deacon swore (as Deacons do,
With an “I dew vum,” or an “I tell yeou,”)
He would build one shay to beat the taown
‘n’ the keounty ‘n’ all the kentry raoun’;
It should be so built that it couldn’ break daown,
“Fur,” said the Deacon, “It’s mighty plain
Thut the weakes’ place mus’ Stan’ the strain;
‘n’ the way t’ fix it, uz I maintain,
Is only jest
T’ make that place uz strong uz the rest.”

First of November, ‘Fifty-five!
This morning the parson takes a drive.
Now, small boys, get out of the way!
Here comes the wonderful one-hoss shay,
Drawn by a rat-tailed, ewe-necked bay.
“Huddup!” said the parson.–Off went they.
The parson was working his Sunday’s text,–
Had got to fifthly, and stopped perplexed
At what the–Moses–was coming next.All at once the horse stood still,
Close by the meet’n’-house on the hill.
First a shiver, and then a thrill,
Then something decidedly like a spill,–
And the parson was sitting upon a rock,
At half past nine by the meet’n’-house clock–
Just the hour of the Earthquake shock!What do you think the parson found,
When he got up and stared around?
The poor old chaise in a heap or mound,
As if it had been to the mill and ground!
You see, of course, if you’re not a dunce,
How it went to pieces all at once,
All at once, and nothing first,
Just as bubbles do when they burst.End of the wonderful one-boss shay.
Logic is logic. That’s all I say.”

It seems that much of modern medicine is concerned with shoring up the weakest parts, so we could indeed end up with our bodies responding sort of like the one-hoss shay.

·         Finally, there will continue to be the bittersweet human relationships, memories and thoughts near the end of life, the difficulty of saying goodbye which may become harder for people who live longer.  So, I expect that aspect of the human condition will remain.

Alzheimer’s disease (AD) is a progressive and fatal disease affecting as many as 5.2 million Americans, the fourth most common cause of death in developing nations.  There are various treatments for symptoms of AD but as of now there is no cure(ref).   My purposes here are 1. to review a chain of research findings that seem to point to the cause of AD and how ultimately to prevent it, and 2.  To review research and clinical trials that may in the more immediate future provide therapies that slow the destructive process of AD.

In case you have forgotten, “Alzheimer’s disease is a neurodegenerative disorder that represents the most important cause of dementia in humans. Extracellular deposits of β-amyloid peptides (Aβ), often termed senile plaques, and formation of intracellular neurofibrillary tangles of hyperphosphorylated tau protein are the two principal hallmarks of this disease. Aβ aggregates are known to induce synaptic dysfunction, and thus are linked with learning and memory deficits in both human and mouse models of the disease, making Aβ deposits a target for prevention or treatment(ref).” 

Microglia are intimately involved in the maintenance of normal brain functioning and in the etiology of many neurodegenerative conditions, including AD.  “Microglia are a type of glial cells that are the resident macrophages of the brain and spinal cord, and thus act as the first and main form of active immune defense in the central nervous system (CNS). Microglia constitute 20% of the total glial cell population within the brain.^] Microglia (and astrocytes) are distributed in large non-overlapping regions throughout the brain and spinal cord.^[1][2] Microglia are constantly excavating the CNS for damaged neurons, plaques, and infectious agents(ref).^[3]”

One role of microglia, that of amplifying pain, was introduced in the blog post Spinal cord injury pain.  There have been various theories as to the involvement of microglia in AD including a very interesting new one.  Physically, “Microglia are attracted to Aβ aggregates and decorate plaques. Such a phenomenon has been observed in both human and transgenic mouse model of Alzheimer’s disease, suggesting an important role for these cells in the CNS(ref).” 

AD, microglia and cellular senescence

Over less than a decade there has been a 180 degree shift from seeing microglial activation as a main cause of AD to seeing microglial senescence as a main cause of AD.