Trending With Impact: A New Marker of Aging and Cellular Senescence

Researchers from the Campisi Lab discovered new insights while investigating Cdkn1a transcript variants 1 and 2.

Embryonic stem cell colony

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The phenomenon in which cells are still metabolically active but can no longer proliferate is known as cellular senescence. Cellular senescence is a normal mechanism in development and tissue homeostasis—and a hallmark of aging.

“Most of my lab works on a process called cellular senescence, which is a cellular response to stresses and damage, many of which increase with age,” Dr. Judy Campisi, Professor at the Buck Institute for Research on Aging and Senior Scientist at the Lawrence Berkeley National Lab, said in a recent Aging interview

An international team of researchers from Dr. Campisi’s lab are in search of new biological markers of cellular senescence and aging. Understanding mechanisms of aging such as senescence is key for developing new, safe interventions that may extend human life—with compounding socioeconomic and cultural impacts. Researchers from this lab come from institutions including the Buck Institute, the University of California, Berkeley’s Lawrence Berkeley National Lab, Universidad de CórdobaUniversidad MayorGeroscience Center for Brain Health and Metabolism, and Unity Biotechnology. The team published a trending 2021 paper in Aging‘s Volume 13, Issue 10, entitled, “Cdkn1a transcript variant 2 is a marker of aging and cellular senescence.” 

“Our results are, to our knowledge, the first to study Ckdn1a transcript variants in the context of aging.”


There are a number of mechanisms that drive cellular senescence. Previously, mRNA and protein coding gene Cdkn1a transcript variant 1 (p21var1) has been better-studied compared to Cdkn1a transcript variant 2 (p21var2). The authors of this paper explain that this is likely because the encoded protein is identical to that encoded by variant 1, and both variants are regulated by p53. However, neither variants have ever before been studied in the context of aging. In this study, the researchers explored the expression levels of both Cdkn1a transcript variants 1 and 2 in the context of cellular senescence using several tissues from aged mice and a cell culture model of mouse cells.

“The stringent cell growth arrest associated with cellular senescence is determined, among other mechanisms, by activities of cyclin-dependent kinase inhibitor proteins p16Ink4a and p21Cip1/Waf1, encoded by the Cdkn2a and Cdkn1a loci, respectively [1].”

Study results showed that both variants are induced during cellular senescence. They showed that p21var1 and p21var2 are equally sensitive to transcriptional upregulation after p53 stabilization. The in vitro models also found that p21var2 is preferentially induced with age.

“In sum, p21var2 expression is consistently elevated with age, in contrast with an absence of age-related change in p21var1 levels.”

The researchers conducted further tests in vivo to examine the expression pattern of p21var2 and their results suggested that the circadian regulation of p21Cip1/Waf1 is driven solely by expression of Cdkn1a transcript variant 1. The team also induced cellular senescence in vivo with doxorubicin and ABT-263 (navitoclax) and evaluated the variants’ expression. These results confirmed their in vitro findings that p21var2 is more prone to cellular senescence than p21var1, thus making it a better marker for assessing the presence of senescent cells in vivo.


“We show that, although tissue-specific exceptions may arise, p21var2 but not p21var1 is a better candidate marker of aging and senescence in mice.”

Click here to read the full research paper, published by Aging.


Aging is an open-access journal that publishes research papers monthly in all fields of aging research and other topics. These papers are available to read at no cost to readers on Open-access journals offer information that has the potential to benefit our societies from the inside out and may be shared with friends, neighbors, colleagues, and other researchers, far and wide.

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2021 Ride for Roswell
2021 Ride for Roswell

Behind the Study: COVID-19 and Chronological Aging

Dr. Michael P. Lisanti from The University of Salford describes his 2020 paper published by Aging, entitled, “COVID-19 and chronological aging: senolytics and other anti-aging drugs for the treatment or prevention of corona virus infection?

Researchers explain their studies that were published in Aging

Behind the Study is a series of transcribed videos from researchers elaborating on their recent oncology-focused studies published by Aging. A new Behind the Study is released each Monday. Visit the Aging YouTube channel for more insights from outstanding authors.

Hi, I’m professor Michael Lisanti and I’m the Chair of Translational Medicine at the University of Salford, and today I want to talk about our new prospective article, which links COVID-19 and chronological aging, and is focused on potential treatments and prevention strategies. I got interested in this topic because there seems to be an association between COVID-19 fatalities and aging, especially in patients with advanced chronological age. Patients over 65, and their 70s and 80s, are more likely to have increased morbidity and mortality. And so, I thought there may be a link there, between aging and senescence and the viral replication, as well as the potential therapy.

What I’d like to highlight about this particular article is that it proposes potential treatment strategies as well as prevention strategies. The reason is because it appears that this disease, the virus itself, may target senescent cells and senescent cells have been rewired to increase protein synthesis and also to increase the secretion of inflammatory mediators, which is known as the SASP, the senescence-associated secretory phenotype.

And so, one idea would be to use drugs that are senolytics. Senolytics are drugs that target and lyse senescent cells, but also to use protein synthesis inhibitors. The reason is because proteins synthesis inhibitors and senolytic drugs would prevent viral replication, which would reduce viral transmission. And so this could be used as a preventative strategy. I’ll just give you a couple of examples. If you have a drug which is an FDA-approved protein synthesis inhibitor, it should inhibit the secretion of inflammatory mediators, like IL-6. It should inhibit the fibrosis by preventing the secretion and production of collagen. And most importantly, the virus is also made of protein, so if you have a protein synthesis inhibitor, it will also inhibit viral replication.

Figure 1. What is the relationship between COVID-19 and advanced chronological age?
Figure 1. What is the relationship between COVID-19 and advanced chronological age?

There are three drugs I’d like to mention in particular. One is azithromycin, which is a senolytic. The others are also protein synthesis inhibitors, like doxycycline and rapamycin. All three have been shown to reduce IL-6 production because of their inhibition of protein synthesis activity. And also, all three of them have been shown to inhibit viral replication, not specifically of COVID 19, but since this effect on protein synthesis is a generalized effect, it should work for any virus. For example, azithromycin has been shown to inhibit the replication of Zika virus and Ebola virus, doxycycline has been shown to inhibit the replication of dengue virus, and rapamycin, which is another protein synthesis inhibitor with anti-aging properties, has been shown to inhibit replication of the HIV virus.

So, it seems to me that it’s a no-brainer that we should be repurposing FDA-approved drugs that are protein synthesis inhibitors, both for prevention, to prevent the inflammation fibrosis that’s occurring that’s killing people with COVID-19, and also to prevent the contagion by inhibiting viral replication. So I think this could provide a very inexpensive way forward because drugs like doxycyclin are only less than 10 cents a day, and could be used, as I said, for both prophylaxis and treatment. But, I think we need to use it early in the disease to prevent the fibrosis and inflammation, which makes them long, very inflexible and unable to expand and contract, and leads them to a fibrotic lung disease, which prevents patient recovery and could explain lethality of the disease.

I would like to directly engage with people to pick this up, to bring this forward as potential clinical trials. These clinical trials could be done directly in healthcare workers because they are the most vulnerable. In addition, they could be done in patients with advanced chronological age, or even with patients that are asymptomatic, that have been identified as the virus-positive. And it would be like a window trial where you would do viral titers first, and then you would give the drug and then you could also look at the viral titers after administering the drugs. So this would be a very easy, straightforward trial.

All the diagnostic tools for COVID-19 have already been identified and perfected, so all we need to do is interject FDA-approved drugs, which are protein synthesis inhibitors, to look at the eradication, the virus. So this would also be a very inexpensive clinical trial. But I would like to engage with infectious disease experts and virologists to help facilitate. Thank you.

Of course, I would like to thank two foundations which have supported our work: The Fox Point Foundation in Canada and The Healthy Life Foundation in the UK for providing the equipment and infrastructure at the University of Salford.

Click here to read the full paper, published by Aging.


Aging is an open-access journal that publishes research papers monthly in all fields of aging research and other topics. These papers are available to read at no cost to readers on Open-access journals offer information that has the potential to benefit our societies from the inside out and may be shared with friends, neighbors, colleagues, and other researchers, far and wide.

For media inquiries, please contact

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