What would you say if I told you that aging happens not because of accumulation of stresses, but rather because of the intrinsic properties of the gene network of the organism? I’m guessing you’d be like: :o.

So, here’s the deal. My biohacker friends led by Peter Fedichev and Sergey Filonov in collaboration with my old friend and the longevity record holder Robert Shmookler Reis published a very cool paper. They proposed a way to quantitatively describe the two types of aging – negligible senescence and normal aging. We all know that some animals just don’t care about time passing by. Their mortality doesn’t increase with age. Such negligibly senescent species include the notorious naked mole rat and a bunch of other critters like certain turtles and clams to name a few. So the paper explains what it is exactly that makes these animals age so slowly – it’s the stability of their gene networks.

What does network stability mean then? Well, it’s actually pretty straightforward – if the DNA repair mechanisms are very efficient and the connectivity of the network is low enough, then this network is stable. So, normally aging species, such as ourselves, have unstable networks. This is a major bummer by all means. But! There is a way to overcome this problem, according to the proposed math model.

The model very generally describes what happens with a gene network over time – the majority of the genes are actually working perfectly, but a small number doesn’t. There are repair mechanisms that take care of that. Also, there are mechanisms that take care of defected proteins like heat shock proteins, etc. Put together all of this in an equasion and solve it, and bam! here’s an equasion that gives you the Gompertz law for all species that have normal aging, and a time independent constant for the negligibly senescent ones.

What’s the difference between those two aging regimes? The model suggests it’s the right combination of DNA repair efficiency and the combined efficiency of proteolysis and heat shock response systems, mediating degradation and refolding of misfolded proteins. So, it’s not the the accumulation of damages that is responsible for aging, but rather the properties of the gene network itself. The good news is that even we are playing with a terrible hand at first, there is a chance we can still win by changing the features of our network and making it stable. For example, by optimizing misfolded protein response or DNA repair.

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Dr DePinho released a paper in 2012, this builds on previous papers and his theory of the “telomere-p53-PGC axis”. This is a big reason along with the work of Dr Michael Fossel I believe telomerase therapy is probably the best chance of radical life extension in the near future. This is one of a number of papers that implicate dysfunctional telomeres in a cascade that causes mitochondrial dysfunction and various other aging consequences.

ABSTRACT Telomere dysfunction activates p53-mediated cellular growth arrest, senescence and apoptosis to drive progressive atrophy and functional decline in high-turnover tissues. The broader adverse impact of telomere dysfunction across many tissues including more quiescent systems prompted transcriptomic network analyses to identify common mechanisms operative in haematopoietic stem cells, heart and liver. These unbiased studies revealed profound repression of peroxisome proliferator-activated receptor gamma, coactivator 1 alpha and beta (PGC-1α and PGC-1β, also known as Ppargc1a and Ppargc1b, respectively) and the downstream network in mice null for either telomerase reverse transcriptase (Tert) or telomerase RNA component (Terc) genes. Consistent with PGCs as master regulators of mitochondrial physiology and metabolism, telomere dysfunction is associated with impaired mitochondrial biogenesis and function, decreased gluconeogenesis, cardiomyopathy, and increased reactive oxygen species. In the setting of telomere dysfunction, enforced Tert or PGC-1α expression or germline deletion of p53 (also known as Trp53) substantially restores PGC network expression, mitochondrial respiration, cardiac function and gluconeogenesis. We demonstrate that telomere dysfunction activates p53 which in turn binds and represses PGC-1α and PGC-1β promoters, thereby forging a direct link between telomere and mitochondrial biology. We propose that this telomere-p53-PGC axis contributes to organ and metabolic failure and to diminishing organismal fitness in the setting of telomere dysfunction.

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An interesting paper that uses ALA to shore up telomerase activity, loss of telomeres inhibition of P53 expression and mitochondrial dysfunction in one go. They use ALA (alpha lipoic acid) to induce PGC-1α in this case though PGC1-alpha seems to be a potential target for intervention as I understand that ALA is difficult to deliver to cells. In this case this involves the vascular system and atherosclerosis.

http://www.cell.com/cell-reports/abstract/S2211-1247(15)00825-6

Short telomeres and Mitochondrial dysfunction are increasingly implicated as being closely linked as this 2012 Dephino paper demonstrates in the aging heart:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3718635/

“On a mechanistic level, recent reports linking telomere dysfunction to metabolic and mitochondrial compromise provide a novel mechanism as to how dysfunctional telomeres can compromise cardiac function. This telomere-p53-PGC-mitochondrial axis aligns with many changes seen in aged hearts: impaired OXPHOS, decreased ATP generation, and increased ROS levels”

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PGC-1α Deficiency Augments Vascular Aging and Atherosclerosis, Coinciding with Telomere Dysfunction and Shortening and DNA Damage through TERT Downregulation.

(A) The aortas from PGC-1α+/+ApoE−/− and PGC-1α−/−ApoE−/− mice (18-month-old males, standard diet, n = 5) were excised for SA-βG staining.

(B) The aortic arch from PGC-1α−/−ApoE−/− and control mice (18-month-old males, n = 5) was dissected for examination of atherosclerotic lesion formation.

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