Fight Aging! Newsletter, October 28th 2019

Wonderful news, the MitoMouse project has successfully reached its initial 50,000 goal and is well on the way towards the first stretch goal! This now means the project will launch at the lab and the MitoMouse strain will be created. The next step for this ambitious project is to actually create progeny from the SickMice and MitoMice in order to have an effective model to test the mitochondrial repair approach, which has already been shown to work in cells, in living animals. If successful it would be vindication for mitochondrial repair therapy and move the therapy closer to translation to humans.

Mice of the C57/BL6MT-FVB strain (let's call them "SickMice") have a mitochondrial gene defect (a mutation in the mitochondrial ATP8 gene) and exhibit several age-related symptoms including lower fertility, arthritis, type II diabetes, and neurological impairments. Since mitochondria are only inherited from the mother, cross-breeding female SickMice with male mice from other models will result in the same mitochondrial dysfunction.

We will use the maximally modifiable model to create a new transgenic mouse (the "allotopic ATP8 transgenic mouse - Mitomouse"). This mouse will have the ATP8 gene that is important for mitochondrial function 'hidden' in the cell nucleus and thus capable of being passed on to offspring irrespective of gender.

Our hypothesis is that both male and female offspring from SickMice crossed with MitoMice will result in rescued mitochondrial function. This would prove the viability of the MitoSENS strategy by showing that functional backup copies of mitochondrial DNA genes in the nucleus can replace their mutated counterparts in live animals.

The TAME trial is an attempt to determine whether metformin, the well-known anti-diabetes drug, actually has much more wide-ranging benefits against the health problems of late life - so wide-ranging, in fact, that they could uncontroversially be described as addressing aging itself. But then, hang on, metformin is an old drug. I mean, a really old drug - it has been off patent since forever. There is no way in hell to make money out of it. So, how would we fund a clinical trial of it? Well, yes: the only way is philanthropic. This will only happen if there are people out there who are sufficiently convinced of the importance of such a trial that they will pony up the requisite capital even though doing so is completely bereft of financial upside.

But the logic is persuasive in another way: precisely because metformin is such an old drug, a trial can immediately focus on efficacy, in contrast to the need for stringent tests of safety to come first in the case of a new drug. And, sure enough, pretty much as soon as the idea of such a trial was formulated, nearly half of the required 75 million was pledged by the long-standing supporter of gerontology research, Paul Glenn, via (as has long been his custom) the American Federation for Aging Research (AFAR). At that point, however, the pursuit of funds stalled for a couple of years - in particular, the National Institute on Aging twice rejected applications for the remaining money - but, as noted above, the remaining support materialised very recently, courtesy of an anonymous donor.

A question remains, however: is this, in fact, the best use of 75 million in the crusade against aging? Well, that's a few times the total amount that SENS Research Foundation has raised in its entire history, so it will not surprise you that I cannot quite look you in the eye and answer that question in the affirmative. But it is certainly not a waste of money either: indeed, I do feel able to declare that it is a pretty good use.

First, I think there is a reasonable chance that the trial will succeed, albeit modestly. There's no way that a brief course of metformin will give people a decade of extra life, but all that's really needed here is a statistically significant improvement versus controls, and with that kind of money the study can be powered well enough to achieve that threshold. The other rationale for this trial is arguably even greater. It is that the description of the trial incorporates a de facto definitition of aging as the clinical endpoint, which has been more-or-less approved by the FDA, and which can thus be copied and pasted into any future trial for an intervention against aging. That endpoint was the result of a highly arduous negotiation with the FDA that was led by the inestimable Nir Barzilai.

Given the relationship between telomeres and ageing - telomeres shorten throughout life, so older organisms have shorter telomeres - scientists launched a study generating mice in which 100% of their cells had hyper-long telomeres. The findings show only positive consequences: the animals with hyper-long telomeres live longer in better health, free from cancer and obesity. "This finding supports the idea that, when it comes to determining longevity, genes are not the only thing to consider. There is margin for extending life without altering the genes".

Telomeres form the end of chromosomes, in the nucleus of each cell in the body. Their function is to protect the integrity of the genetic information in DNA. Whenever the cells divide the telomeres, they are shortened a little, so one of the main characteristics of ageing is the accumulation of short telomeres in cells. Up to now, all interventions on the length of telomeres have been based on altering the expression of genes, through one technique or another. In fact, researchers developed a gene therapy that fosters the synthesis of telomerase, obtaining mice that live 24% longer without developing cancer of other illnesses associated with age.

In 2009, researchers worked with the so-called induced pluripotent stem cells - cells from an adult organism which have been given back pluripotency or the capacity to generate a full organism - and they observed that after a certain number of divisions in culture plates, these cells acquired telomeres twice as long as normal. Intrigued, they confirmed that the same occurred in normal embryonic cells - also pluripotent - as they are kept in cultivation after being removed from the blastocyst. The team found that during the pluripotency stage, there are certain epigenetic marks on the telomeric chromatin that facilitate their lengthening by the telomerase enzyme. For this reason, the telomeres of pluripotency cells in cultivation were extended to twice the normal length.

The question was whether the embryonic cells with hyper-long telomeres could produce live mice? Some years ago, the group demonstrated that they could, and have now managed to obtain mice with hyper-long telomeres in 100% of their cells. The mice are slimmer than normal because they accumulate less fat. They also show lower metabolic ageing, with lower levels of cholesterol and LDL, and an increased tolerance to insulin and glucose. Damage to their DNA as they age is less and their mitochondria, another Achilles heel of ageing, function better. The average longevity of mice with hyper-long telomeres is 13% higher than usual. The metabolic alterations observed are also relevant as this is the first time that a clear relationship between the length of telomeres and metabolism has been found. The genetic route of insulin and glucose metabolism is identified as one of the most important in relation to ageing.

Short telomeres trigger age-related pathologies and shorter lifespans in mice and humans. In the past, we generated mouse embryonic (ES) cells with longer telomeres than normal (hyper-long telomeres) in the absence of genetic manipulations, which contributed to all mouse tissues. To address whether hyper-long telomeres have deleterious effects, we generated mice in which 100% of their cells are derived from hyper-long telomere ES cells. We observe that these mice have longer telomeres and less DNA damage with aging. Hyper-long telomere mice are lean and show low cholesterol and LDL levels, as well as improved glucose and insulin tolerance. Hyper-long telomere mice also have less incidence of cancer and an increased longevity. These findings demonstrate that longer telomeres than normal in a given species are not deleterious but instead, show beneficial effects.

Under ordinary circumstances, tau contributes to the normal, healthy functioning of brain neurons. In some people, though, it collects into toxic tangles that are a hallmark of neurodegenerative diseases such as Alzheimer's. Researchers had shown that microglia limit the development of a harmful form of tau. But they also suspected that microglial cells could be a double-edged sword. Later in the course of the disease, once the tau tangles have formed, the cells' attempts to attack the tangles might harm nearby neurons and contribute to neurodegeneration.

To understand the role of microglial cells in tau-driven neurodegeneration, researchers first studied genetically modified mice that carry a mutant form of human tau that easily clumps together. Typically, such mice start developing tau tangles at around 6 months of age and exhibiting signs of neurological damage by 9 months. Then, the researchers turned their attention to the gene APOE. Everyone carries some version of APOE, but people who carry the APOE4 variant have up to 12 times the risk of developing Alzheimer's disease compared with those who carry lower-risk variants. The researchers genetically modified the mice to carry the human APOE4 variant or no APOE gene. APOE4 amplifies the toxic effects of tau on neurons.

For three months, starting when the mice were 6 months of age, the researchers fed some mice a compound to deplete microglia in their brains. Other mice were given a placebo for comparison. The brains of mice with tau tangles and the high-risk genetic variant were severely shrunken and damaged by 9 months of age - as long as microglia were also present. If microglia had been eliminated by the compound, the mice's brains looked essentially normal and healthy with less evidence of harmful forms of tau despite the presence of the risky form of APOE. Further, mice with microglia and mutant human tau but no APOE also had minimal brain damage and fewer signs of damaging tau tangles. Additional experiments showed that microglia need APOE to become activated. Microglia that have not been activated do not destroy brain tissue or promote the development of harmful forms of tau.

Chronic activation of brain innate immunity is a prominent feature of Alzheimer's disease (AD) and primary tauopathies. However, to what degree innate immunity contributes to neurodegeneration as compared with pathological protein-induced neurotoxicity, and the requirement of a particular glial cell type in neurodegeneration, are still unclear. Here we demonstrate that microglia-mediated damage, rather than pathological tau-induced direct neurotoxicity, is the leading force driving neurodegeneration in a tauopathy mouse model. Importantly, the progression of phosphorylated tau pathology is also driven by microglia.

In addition, we found that APOE, the strongest genetic risk factor for AD, regulates neurodegeneration predominantly by modulating microglial activation, although a minor role of apoE in regulating phosphorylated tau and insoluble tau formation independent of its immunomodulatory function was also identified. Our results suggest that therapeutic strategies targeting microglia may represent an effective approach to prevent disease progression in the setting of tauopathy.

On October 22, Biogen stunned the Alzheimer's field by announcing that aducanumab - presumed dead last March after failing a futility analysis - appears to have worked in one of its two Phase 3 trials, after all. Based on the results of a new analysis, and interactions with the FDA, Biogen will file for regulatory approval in early 2020. Why the revival? The interim futility analysis was flawed and did not adequately take into account the effect of two late protocol amendments that boosted the number of people receiving the highest dose of this biologic drug. A new analysis included three more months of data, as well as data from the participants who did not complete the full course of treatment. It showed that one of the two trials, called EMERGE, in fact met its primary and secondary endpoints. Oddly, the identical ENGAGE trial, which started one month earlier, was a tad larger, yet had slightly fewer people who took an uninterrupted course of the maximum dose, remained negative.

In each trial, about half the participants on aducanumab were randomly assigned to titrate up to a low dose of drug - 3 mg/kg for ApoE4 carriers, 6 mg/kg for noncarriers. This difference was because ApoE4 carriers are more susceptible to ARIA, the fluid retention in the brain that accompanies treatment with many amyloid-removing therapies. In the high-dose group, ApoE4 carriers initially titrated up to 6 mg/kg; noncarriers to 10 mg/kg. However, in March 2017, about 18 months into the trial, the protocol was amended to allow ApoE4 carriers to titrate up to 10 mg/kg, as well. This was based on accumulating data from several studies suggesting that ARIA is a manageable side effect that usually resolves without harm.

Analysis of the more recent, larger data set suggested that duration of treatment at the high dose was the key factor. In addition, interruption of treatment played a role. In EMERGE, participants on the low dose had a trend of declining more slowly than those on placebo on the primary outcome, the CDR Sum of Boxes, but this was well shy of statistical significance. Participants on the high dose declined 23 percent more slowly than those on placebo, with a significant p value of 0.01. Secondary endpoints were similar. The high-dose group declined about a quarter less on the ADAS-Cog13, a cognitive battery, and up to 46 percent more slowly on the ADCS Activities of Daily Living, a caregiver assessment.

Declining stem cell function during aging leads to impaired tissue function and contributes to delayed tissue repair following damage. In adult skeletal muscle, loss of myofiber integrity caused by mechanical injuries or diseases are repaired by resident muscle stem cells (MuSCs), called satellite cells, which promptly exit from quiescence after disruption of muscle architecture to expand, differentiate, and drive tissue regeneration. The fate of MuSCs fundamentally depends on the "niche", their local environment, which is orchestrated by diverse cellular and acellular elements.

Fibro/adipogenic progenitors (FAPs) constitute a population of interstitial mesenchymal cells in skeletal muscle which are devoid of myogenic potential, but support muscle stem cell commitment and can differentiate to the adipogenic or fibrotic lineages. A recent study demonstrated an important function of FAPs in maintaining long-term homeostasis of skeletal muscle: long term in-vivo depletion of FAPs decreased the number of MuSCs and reduced muscle mass and strength, suggesting a critical role of FAPs in maintaining the stem cell pool and sustaining myofiber growth and turnover.

The decline of MuSC function and muscle regenerative capacity during aging is under the control of a wide range of signals, out of which many arise from extrinsic cues coming from the local or systemic environment. A recent study investigated how aging influences the fate of FAPs and their cross-talk with MuSCs to regulate the balance between myogenesis, adipogenesis and fibrosis in skeletal muscle. Aging causes a clonal selection of FAPs, which favors their fibrogenic over adipogenic conversion. Interestingly, aged FAPs fail to efficiently amplify following muscle injury and aging alters the capacity of FAPs to support MuSC amplification and commitment. Both in-vitro co-culture and in-vivo transplantation of young FAPs rejuvenate aged MuSC function, but aged FAPs lose the ability to efficiently support MuSCs. The fact that the support of FAPs to MuSCs is communicable via conditioned medium suggested that soluble factors regulate this paracrine cross-talk.

Future research will be necessary to further dissect FAP function during homeostasis and tissue repair and unravel how the heterogeneity of this population is orchestrated in health and disease. In particular, the signals that mediate FAP dysfunction and the spatio-temporal control of their fate and interactions with MuSCs will be key to understand how aging of different compartments of the stem cell niche contribute to global regenerative capacity.

Microglia, the resident immune cells in the central nervous system, are key players in maintaining homeostasis in the brain. Microglia play a wide variety of roles under physiological and pathological conditions. In the healthy brain, microglia are responsible for neuronal activity-dependent synapse pruning during postnatal development. Upon neuronal injury or infection, microglia become rapid responders that initiate an innate inflammatory response. If the inflammatory response is exaggerated or chronic, it becomes detrimental for the surrounding neuronal population, as in Parkinson's disease and Alzheimer's disease.

Epigenomic mechanisms regulate distinct aspects of the inflammatory response in immune cells. Despite the central role for microglia in neuroinflammation and neurodegeneration, little is known about their epigenomic regulation of the inflammatory response. Here, we show that Ten-eleven translocation 2 (TET2) methylcytosine dioxygenase expression is increased in microglia upon stimulation with various inflammogens through a NF-κB-dependent pathway.

We found that TET2 regulates early gene transcriptional changes, leading to early metabolic alterations, as well as a later inflammatory response independently of its enzymatic activity. We further show that TET2 regulates the proinflammatory response in microglia of mice intraperitoneally injected with lipopolysaccharide. We observed that microglia associated with amyloid β plaques expressed TET2 in brain tissue from individuals with Alzheimer's disease and in 5xFAD mice. Collectively, our findings show that TET2 plays an important role in the microglial inflammatory response and suggest TET2 as a potential target to combat neurodegenerative brain disorders.

Senescence is a cellular stress response that results in the stable growth arrest of old and damaged cells. The past decade has revealed that senescent cells play important roles in a growing list of diseases from cancer, to arthritis, atherosclerosis, and many more. Previous studies have shown that the specific elimination of senescent cells with drugs or using genetic tricks makes mice live healthier for longer. Eliminating senescent cells results in improvements in fibrosis, cataracts, atherosclerosis and in more than 20 other diseases.

After examining a library of drugs that are already used in the clinic and testing them on normal and senescent cells, the researchers identified ouabain as a potential candidate to selectively kill senescent cells. Ouabain belongs to a family of natural compounds called cardiac glycosides that include also digoxin and digitoxin. Cardiac glycosides are used in the clinic to treat cardiac arrythmias and atrial fibrillation. In this study it was found that cardiac glycosides selectively eliminate many types of senescent cells, including when senescence has been triggered by irradiation, cancer itself, or chemotherapeutic drugs - such as etoposide or doxorubicin. The fact that ouabain can eliminate different types of senescent cells emphasises its potential as a broad spectrum senolytic.

"These drugs are already used in the clinic, so they could be repurposed to treat a long list of diseases including cancer. This is something we are keen to explore with our clinical collaborators. Moreover, many patients are being treated with digoxin and an epidemiologist could look retrospectively and ask the question of whether those patients who were treated with digoxin are doing better than those who weren't."

Experimental and observational clinical evidence suggests a prominent role of inflammation in the development of hypertension. In particular, activation of immune cells has been demonstrated in hypertension. Hypertension is more prevalent in patients with immune-mediated disorders, such as psoriasis, rheumatoid arthritis or systemic lupus erythematosus. Thus, chronic inflammatory disorders, could provide a substrate for the pro-hypertensive inflammation.

Periodontitis is one of the most common inflammatory conditions worldwide, representing the sixth most prevalent condition worldwide with prevalence of 20-50%. It is linked to cardiovascular inflammation and endothelial dysfunction. Therefore, if causally associated, periodontitis could significantly contribute to the global hypertensive burden and interventions targeting oral inflammation would have an important role in the prevention of hypertension and its complications. Observational evidence suggests that moderate-severe periodontitis is associated with increased odds for hypertension.

Because of this, it is imperative to establish if periodontitis can cause hypertension. Our group has recently shown that immune activation induced by a keystone periodontal pathogen (Porphyromonas gingivalis) promotes the development of hypertension in mice. Small interventional studies concluded that intensive periodontal therapy may lead to blood pressure reduction, although sufficiently powered evidence in well-defined hypertensive cohorts is lacking. We thus performed a randomized intervention trial on the effects of treatment of periodontitis on blood pressure. One hundred and one hypertensive patients with moderate to severe periodontitis were randomized to intensive periodontal treatment (IPT) or control periodontal treatment (CPT) with systolic blood pressure (SBP) as the primary outcome.

Intensive periodontal treatment improved periodontal status at 2 months, compared to CPT. This was accompanied by a substantial reduction in mean SBP in IPT compared to the CPT (mean difference of -11.1 mmHg). Systolic BP reduction was correlated to periodontal status improvement. Diastolic blood pressure and endothelial function (flow-mediated dilation) were also improved by IPT. These cardiovascular changes were accompanied by reductions in circulating IFN-γ and IL-6 as well as activated and immunosenescent CD8+ T cells, previously implicated in hypertension.

Researchers are exploring the cause and effect relationships between common health indicators and lifespan, by analyzing polygenic risk scores (PRS), a numerical score of a person's risk for disease based on multiple genetic variants. To find a clinically actionable indicator of genetic risk, researchers started by examining samples from BioBank Japan, which has a heavy East Asian representation. They used the genetic data of 180,000 people to perform genome-wide association studies for 45 common health indicators. By analyzing the PRS of each indicator, they identified the ones that most strongly affected lifespan.

"If you only look at raw clinical data associated to lifespan, you cannot show which attribute is cause and which is effect. For instance, when a patient is dying, their blood pressure is low, so you can't necessarily know if blood pressure is the cause of their death. By using PRS, we can get closer to identifying the cause, because PRS is less susceptible to the acquired confounding factors such as decline in general health."

For the individuals in BioBank Japan, researchers found that high blood pressure and obesity had the most significant associations to reduced lifespan. To improve the diversity of their study and ensure that these associations held across populations, the researchers collaborated with the UK Biobank and FinnGen, and performed a trans-ethnic association study of PRS and lifespan. This increased the sample size to 700,000 and, with the help of additional analyses, reinforced the conclusion that blood pressure and obesity are causally related to reduced lifespan.

Researchers began their investigation by analyzing gene expression patterns in donated brain tissue from hundreds of people who died at ages ranging from 60 to over 100. The information had been collected through three separate research studies of older adults. Those analyzed in the current study were cognitively intact, meaning they had no dementia. Immediately, a striking difference appeared between the older and younger study participants: The longest-lived people - those over 85 - had lower expression of genes related to neural excitation than those who died between the ages of 60 and 80.

Next came the question that all scientists confront: correlation or causation? The team conducted a barrage of experiments, including genetic, cell and molecular biology tests in the model organism Caenorhabditis elegans; analyses of genetically altered mice; and additional brain tissue analyses of people who lived for more than a century.

These experiments revealed that altering neural excitation does indeed affect life span-and illuminated what might be happening on a molecular level. All signs pointed to the protein REST. REST, which is known to regulate genes, also suppresses neural excitation, the researchers found. Blocking REST or its equivalent in the animal models led to higher neural activity and earlier deaths, while boosting REST did the opposite. And human centenarians had significantly more REST in the nuclei of their brain cells than people who didn't make it past their 70s or 80s.

The researchers found that from worms to mammals, REST suppresses the expression of genes that are centrally involved in neural excitation, such as ion channels, neurotransmitter receptors and structural components of synapses. Lower excitation in turn activates a family of proteins known as forkhead transcription factors. These proteins have been shown to mediate a "longevity pathway" via insulin/IGF signaling in many animals. It's the same pathway that scientists believe can be activated by caloric restriction.

The clinical trial (NCT04133649) has just began recruitment stage. The procedure will consist of a single intravenous injection, followed by six safety and efficacy evaluations. Participants will receive adeno-associated virus (AAV) containing gene expressing telomerase reverse transcriptase enzyme. AAV is expected to move from the circulatory system to tissues, invade cells, and establish telomerase expression inside cells. Viruses will not modify the genome - AAV's genetic material normally exists separately in the cell cytoplasm (as an episome).

Formally, the study is phase I trial, which limits the main goal - whether it is successful or failed attempt - to safety only. In this case, the primary goal was declared as the incidence of adverse effects. Determination of dosing and tolerability is an important first step in all gene therapies. High doses of viral particles result in significant immunological reaction. Moreover, liver damage is a common adverse effect in early gene therapies, because of liver's participation in blood filtering. In addition, telomerase introduces additional risk on its own. In 85% cases of cancers, telomerase is found upregulated, which raises concerns about potential oncogenicity of AAVs with hTERT gene.

The trial is accompanied by two similar phase I attempts (NCT04133454, NCT04110964), which target Alzheimer's disease and critical limb ischemia. Patients participating in the trial will be enrolled in their country of origin and will travel to Colombia. Patients will stay in Colombia for a few days while the treatment is administered and hospitalized for observation. Patients will then return to their country of origin and will be followed-up per the study protocol.

Long-lasting changes at synapses enable memory storage in the brain. Although aging is associated with impaired memory formation, it is not known whether the synaptic underpinnings of memory storage differ with age. Using a training schedule that results in the same behavioral memory formation in young and aged mice, we examined synapse ultrastructure and molecular signaling in the hippocampus after contextual fear conditioning.

Only in young, but not old mice, contextual fear memory formation was associated with synaptic changes that characterize well-known, long-term potentiation, a strengthening of existing synapses with one input. Instead, old-age memory was correlated with generation of multi-innervated dendritic spines (MISs), which are predominantly two-input synapses formed by the attraction of an additional excitatory, presynaptic terminal onto an existing synapse. Accordingly, a blocker used to inhibit MIS generation impaired contextual fear memory only in old mice.

Memory reconsolidation has been suggested to update memory storage. Reconsolidation involves initial destabilization followed by protein-synthesis-dependent restabilization. Destabilization can be analyzed when restabilization is blocked. To our knowledge, destabilization has only been studied at a young age. An earlier study suggested that reconsolidation is impaired in aged rats and humans. However, this study did not block protein synthesis to assess memory destabilization.

Here, we show that memory destabilization is impaired in aged mice. We detected this impairment using a re-exposure protocol that induces destabilization of strong contextual fear memory in young mice. Thus, in old age, memory destabilization may not only be impaired, it may be completely blocked. It is conceivable that impaired memory destabilization in aging is due to the involvement of MISs, as the reversal of these multi-input synapses into one-input synapses might not be induced by retrieval. An MIS-based memory-storing mechanism may explain why memory updating, a fundamental cognitive process, is impaired in old age.

Heart attack and stroke are the primary cause of death worldwide. When a blood clot forms, it blocks the blood vessel and blood circulation. The non-irrigated tissues no longer receive oxygen and rapidly undergo necrosis, from which they cannot recover. But what causes the necrosis under these conditions? Not all animals are so sensitive to the absence of oxygen, worms can live three days without oxygen, some turtles can live several months, and certain bacteria indefinitely.

The researchers saw that in worms a particular species of ceramide, deoxydihydroceramide, accumulated to dangerous levels under anoxia, that is when tissues were completely deprived of oxygen. Upon an infarct, the synthesis of deoxydihydroceramide increases and becomes toxic for cells. Using mass spectrometry, researchers observed that this ceramide blocks certain protein complexes and provokes defects in the cytoskeleton of cells and the proper function of mitochondria, causing tissue necrosis.

Based on these results, researchers injected an inhibitor of ceramide synthesis in mice just before a heart infarct. They found that the mice that received the injection have 30% less tissue necrosis when compared to control mice that received an injection without the inhibitor. The researchers are now working on an inhibitor that will target more specifically deoxydihydroceramide, which is likely to have fewer side effects and maintain the normal body functions of ceramides.

In order to study autophagy, researchers have created a mouse model that has increased levels of autophagy. This is performed by mutating a component of what is called the beclin 1-BCL2 regulatory complex. When BCL2 binds beclin 1, autophagy is turned off. The engineered mutation in beclin 1 prevents BCL2 from binding, and allows beclin 1 to continue to promote the formation of the autophagosome, which results in continuously higher levels of autophagy in the mice.

The results of this study demonstrate that the mice with increased levels of autophagy have a significantly increased lifespan. Studies showed that not only do these beclin 1 mutant mice live longer, but also healthier, having better kidney and heart function as well as less spontaneous tumor formation. Additionally, their premature lethality and infertility is rescued. These results suggest that promoting autophagy in this manner can promote mammalian healthspan and lifespan and should be further studied.

The researchers then wondered if known anti-aging compounds could be producing their effects through a pathway similar to their genetic mouse model. Klotho, a membrane protein, was one such compound they examined. It has previously been shown that animals genetically engineered to be deficient in klotho have reduced lifespan and that administering klotho could extend lifespan. Additionally, it was observed that administering klotho promoted more autophagy. Researchers took klotho-deficient mice and observed a noticeable increase in beclin 1-BCL2 binding, leading to less autophagy. By taking these klotho deficient mice and mutating beclin 1 they were able to rescue the effects of klotho deficiency and return autophagy to normal. Furthermore, by administering klotho to human HeLa cells they were able to reduce beclin 1-BCL2 binding showing that this effect is not isolated to mice, but applicable to humans as well.