A new study by Harvard professor Ronald A. DePinho, just published in Nature, shows dramatic reversal of aging in mice. The “biological clock” of these mice had been modified to make them age rapidly. This was done with genetically engineering which “knocked out” the gene that makes telomerase, the enzyme responsible for maintaining the telomeres. These genetically manipulated mice had short telomeres, and premature aging with atrophy (shrinkage) of the brain, spleen, loss of sense of smell, and loss of fertility with testicular atrophy.
Reversing Aging with the “The Ponce De Leon Effect”
The next step of the experiment was to give back the missing gene for telomerase and see if that would reverse all these signs of aging in the mice. For this next step, the aged mice were treated with a drug (4-OHT) which served to “turn on” production of telomerase and lengthen the telomeres. This dramatically reversed the signs of aging with the aged mice surprisingly rejuvenated. Their shrunken brains, spleens and testes resumed normal size, and they regained their sense of smell. The aged infertile males once again became fertile, and fathered large litters. Is this the next anti-aging breakthrough? Can treatment to restore telomerase and telomere length potentially restore organ function and reverse degenerative disease in the elderly?
Telomeres are the biological clock that control aging and cell replication. They are small strands of DNA code at the end of each chromosome (see diagram above). Each time the cell replicates itself, the telomere shortens a little bit and eventually, after about 50 replications, cell replication stops in a process known as “cell senescence”, or the Hayflick limit.
Carol Greider and colleagues were awarded the 2009 Nobel Prize in Medicine for their discovery and work on telomerase, the enzyme that lengthens telomeres. In 1984, Greider discovered the enzyme telomerase and later she found that telomerase can prevent shortening of the telomeres, which prevents and reverse the aging process. Her findings were published in 1985 in the journal, Cell. Later, in 1997, Greider collaborated with Ronald A. DePinho to produce a telomerase “Knockout Mouse”, a mouse genetically modified to have the telomerase enzyme removed, causing short telomeres and premature aging. This was the rapid aging mouse model used by DePinho in his new study published in Nature.
The role of Estrogen in Turning on Telomerase Activity
By now, it is should be obvious to you that activating telomerase, protects the telomeres from shortening and serves as an anti-aging treatment, slowing or reversing aging. On the contrary, knocking out or inhibiting telomerase activity results in shortened telomeres with acceleration of the aging process. So what activates Telomerase ?
The answer to this question can be found in an excellent 2002 review article by Cong entitled, “Human Telomerase and Its Regulation “. Among other things, the bioidentical hormones, 17 beta estadiol (estrogen) activates telomerase. The major mechanism for control and activation of telomorase is the hTERT promoter gene which stands for the human Telomerase Reverse Transcriptase (hTERT) gene. When the hTERT gene is sequenced, and the code examined, one finds two estrogen receptor elements in this gene. This explains why 17-beta estradiol activates telomerase.
Simply put, the fact that there are estrogen receptors in the TERT gene means that estrogen activates telomerase.
The role of Tamoxifen
Estrogen blockers such as tomoxifen block these receptors and turn off telomerase. Androgens were also found to turn on the hTERT gene and activate telomerase, and as expected, androgen blocker drugs inhibit telomerase. Although much of the scientific research on telomerase activity has focused on estrogen (a bioidentical hormone) as the regulator and activator of telomerase activity, the DePinho Harvard group did something different. They genetically modified the mouse TERT gene so they could use a synthetic hormone called 4-OHT, which is actually Tamoxifen. Normally, Tamoxifen is an estrogen receptor blocker and inhibitor of telomerase activity. The Depinho group did some genetic gymnastics and modified the genes of the mice so the Tamoxifen would activate the TERT gene, rather than inhibit it.
Tamoxifen, originally made by Astra-Zeneca, had global sales in 2001 of a billion dollars. This was a big seller, a blockbuster. As you might guess, Astra-Zeneca is a large pharmaceutical company with deep pockets for funding academic research. So, why did the Harvard group use a synthetic hormone called 4-OHT, to increase telomere length when research over the past decade shows that 17 Beta-Estradiol is the natural agent for this? Why not use 17-Beta Estradiol to produce the same anti-aging effects as the DePinho mouse telomere study?
Bioidentical Hormones are the Most Logical Choice
Whether you happen to be a human being or a mouse, then the most logical and effective way to increase telomerase activity, lengthen the telomeres and reverse aging is with the human bioidentical hormone, 17-Beta-Estradiol, also known as estrogen. In 1999, more than a decade ago, Kyo demonstrated that 17-Beta-Estradiol activates telomerase via direct and indirect effects on the hTERT promoter region.
In 2000 Silvia Misiti showed that telomerase activity and TERT gene expression is regulated by and dependent on 17 Beta Estradiol, which by the way, is a Bioidentical Hormone. In 2008, Bayne showed that estrogen deficiency in mice leads to telomere shortening and rapid aging. Another study in 2009 by Rodrigo T. Calado from the NIH showed that 17-Beta-Estradiol was effective in increasing TERT gene expression and telomerase enzymatic activity. Quite contrary to DePinho’s mouse aging model, the beneficial effect of 17-Beta Estradiol on telomerase function was abolished by Tamoxifen, an estrogen blocker drug.
A recent December 2010 study from Imanishi from Japan showed that 17-Beta-Estradiol (estrogen) augments telomerase activity, thereby accelerating recovery after injury and reducing the effects of aging (reducing senescence). If this isn’t a description of anti-aging effects, I don’t know what is.
Published in the journal Gut in 2004, Sato found that Estradiol prevents telomere shortening in normal human liver cells, as well as in a mouse model of chemically induced liver cirrhosis. Sato states that estradiol is the preferred treatment and superior to Dr. Depinho’s genetic engineering proposals. An important study in Circulation 2006 found that 17-Beta Estradiol enhances recovery after heart attacks by augmenting incorporation of endothelial stem cells and inducing new collateral vessels in the ischemic myocardium. This beneficial effect is related to telomerase activation of the Endothelial Progentior cells.
Bioidentical Hormones Levels Decline After Age 50
Bioidentical hormones are the hormones normally found in the human body. After age 50, hormone levels decline in men and women, heralding the onset of degenerative changes also known as aging. It makes sense to replenish these hormones to normal levels which we now know activates telomere lengthening, and reverses senescence.
In real life, Tamoxifen is anti-estrogen and acts to inhibit telomerase activity. So, you might be wondering why DePinho’s group did some genetic engineering gymnastics to get the right receptors loaded onto the TERT gene, so that Tamoxifen could be used as the promoter drug, a drug that actually blocks the effect of 17-Beta Estradiol and is a TERT inhibitor in actual real life. It’s all about Big Business and Big Pharma.
If you are wondering if telomere research at Harvard is tainted by Big Business and Big Pharma money, the answer is yes, of course. It’s all disclosed in the public record . The anti-aging mouse study author, Dr. DePinho received more than $83,000 dollars as a consultant to the Glaxo-Smith Klein drug company in 2009-2010. Dr DePinho also co-founded Karyopharm, a privately held Oncology company which recenty raised $20 Million in financing for its line of Novel Nuclear Transport Modulators. Dr DePinho is also one of the Directors at the Dana-Farber Cancer Institute which recently raised 1 Billion Dollars to fund its research activities (how much of this from Big Pharma?). So yes, of course, there is big money and big pharma involved in the halls of academic medicine, and this explains why a synthetic drug like 4-OHT (4 hydroxy tamoxifen) was used in the mouse telomere study instead of the more logical choice of 17 beta estradiol (estrogen).
The Race for Natural Substances That Activate Telomerase and Reverse Aging
Resveratrol, Silymarin and Gingko Biloba are natural substances found to activate telomerase with potential for anti-aging. Calvin Harley of Geron Corporation, and John Anderson and William H Andrews of Sierra Sciences are leading the race to develop safe products as nutritional supplements to activate telomerase and reverse aging. Dr. Andrews says “Telomerase activation technology promises to be the most significant advance in human health since germ theory.”
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