A naturally occurring short form of p53 reduced cellular senescence and extended lifespan in mice with progeria, without the surge in tumors typically seen when the gene is completely disabled

A naturally occurring short form of p53 reduced cellular senescence and extended lifespan in mice with progeria, without the surge in tumors typically seen when the gene is completely disabled

On 7 October 2026, biologists at the US National Cancer Institute reported in npj Aging the first whole-organism study of Δ133p53α, a naturally occurring p53 isoform previously studied in cultured cells. In mice with Hutchinson-Gilford progeria, an inherited disorder that causes accelerated aging, the isoform reduced signs of cellular senescence in several organs and modestly extended lifespan.

p53 is one of the most extensively studied genes in cancer biology. In response to DNA damage, it activates p21, which permanently stops a cell from dividing and prevents it from becoming cancerous. This permanent arrest is cellular senescence. Disabling this pathway carries a risk: cells lacking p53 or p21 survive longer in culture, but mice die sooner from tumors.

Humans have a natural brake on this process: Δ133p53α, a short form of p53 that lacks the first 132 amino acids. It binds to full-length p53 and specifically blocks its signal for cellular senescence while leaving its DNA repair function largely intact. Izumi Horikawa’s laboratory had already demonstrated this effect in cultured human cells; the new study is the first to show it in a whole organism.

The researchers developed a mouse line with a controllable Δ133p53α gene and crossed it with a short-lived progeria model carrying an LMNA mutation. The model’s short lifespan allows researchers to assess effects on lifespan more quickly. In mice with Δ133p53α switched on, all three markers fell in the skin, muscle, kidney, spleen and lung: p21, the inflammatory protein IL-6 and γ-H2AX, a marker of DNA breaks.

In progeria, this process forms a feedback loop across tissues: senescent cells release inflammatory signals that accelerate senescence in neighboring cells. A review of twenty years of progeria research described this same sequence. The decline in IL-6 across all five tissues interrupts the loop at an early stage.

In the aorta and skin, tissues particularly affected by progeria, the transgene protected smooth muscle cells from death, prevented thinning of the skin and subcutaneous fat, and preserved a hair follicle stemness marker that disappeared in its absence.

Median lifespan in these mice rose from 349 to 387 days, an increase of 11% that the authors described as modest but statistically supported. Comparable interventions in the same model, such as CRISPR gene editing or cellular reprogramming, extended lifespan by 25–30%.

In another study, mice with a similar engineered variant, Δ122p53, developed more tumors, had greater inflammation and lived shorter lives. These findings show that shortening p53 can also have harmful effects. Both variants suppressed IL-6 to the same extent in cultured cells; the authors do not know why their effects differ in whole organisms.

The same effect was reproduced in ordinary aged mice: the transgene reduced p21 and increased the number of smooth muscle cells in the aortic wall. Human data from the GTEx gene expression database show that skin levels of Δ133p53α fall after age 60 as p53 and p21 rise. This provides an initial indication that this brake also weakens with age in humans.

RNA sequencing of the heart and kidney indicated greater mitochondrial energy production and antioxidant protection, along with less inflammation, in mice carrying the transgene. In the aorta, age-related changes in histone marks were partially reversed. Histones are proteins that package DNA and regulate gene activity.

The study provides proof of principle: the transgene was switched on before disease symptoms appeared. A possible route toward a drug has also been identified, with a screen finding two compounds that increase Δ133p53α in human cells. Leo Yamada, one of the study’s two authors, died before the paper was published; it is dedicated to his memory.