How Fast Does the DNA Repair Leader in Your Cells Take Control?

Clusters of proteins seem to significantly influence the rate of DNA repair within our bodies, which in turn determines how quickly mutations accrue in cells throughout one’s life. This dynamic can significantly influence both aging and lifespan.

“It is a very reliable indicator of lifespan across humans and other animals,” states Trey Ideker from the University of California, San Diego. His research team aims to discover treatments that might enhance lifespan by increasing DNA repair mechanisms.

Some researchers assert that the evidence linking this specific protein complex—a collection of two or more proteins that collaborate for a biological function—to mutation rates is compelling. However, more investigation is necessary to concretely establish the relationship between aging and longevity.

Regarding why we age, one proposed theory is that it results from the gradual accumulation of mutations in cellular DNA. As these mutations pile up, the functionality of cellular machinery declines, leading to a cascade of issues.

Cells act like repair teams that address broken DNA, yet their efforts aren’t always adequate. In fact, the efficacy of DNA repair varies, likely influenced by genetic factors.

Ideker’s team has currently compiled evidence indicating that a protein complex known as Dream acts as a master regulator of DNA repair. This complex operates like a supervisor for the repair team. Each complex, potentially existing in numerous identical copies in every cell, is formed by various proteins, and the acronym DREAM reflects the names of its components.

Initially, DREAM was thought to control cell division, but it is now known to repress hundreds of genes tasked with DNA repair, including BRCA2, a gene that heightens breast cancer risk when mutated.

The research group created a metric for DREAM activity by scrutinizing the over 300 genes they initially manage. “This study aims to demonstrate unmistakably that high DREAM activity correlates with increased aging and reduced longevity, while low DREAM activity is favorable for longevity,” he explains.

Using data from studies involving over 100,000 mouse cells across various tissues, the researchers established that cells exhibiting greater DREAM activity harbor more mutations. Subsequently, they examined data from 92 mammalian species and confirmed a strong correlation between reduced DREAM activity and extended maximum lifespans.

In another facet of their experiment, they scrutinized data from a study involving 90 cells, including 80 individuals with Alzheimer’s disease, discovering a connection between DREAM activity and increased risk.

The team also engineered mice to lack the DREAM complex; this was a challenging task since each constituent protein has a unique role, and the entire complex is crucial for cell division early in development. Mice without it would not survive.

To navigate this challenge, they employed a drug-induced genetic strategy to deactivate the DREAM genes when the mice reached 8 weeks of age. The knockout mice exhibited 20% fewer deletion and insertion mutations in brain cells compared to their normal counterparts as they aged, though Ideker notes that the disruption to their lifespan didn’t reflect a significant extension. “The experimental design may not have been suited to uncover that,” he admits. “We now aim to conduct a more conclusive experiment linking it to extended lifespan.”

Despite this, Ideker believes the amassed evidence paints a clear picture. “Our findings indicate that DREAM plays a crucial role in aging and is indeed a significant factor in the accumulation of lifelong mutations,” he asserts.

“These are groundbreaking and significant findings,” remarks JoeãO Pedro de Magalhães from the University of Birmingham, UK. “The data from their mouse studies indicate a causal connection between DREAM and mutation levels,” he notes; however, the researchers haven’t yet established a direct causal link with aging. “To prove this, we must demonstrate that mice exhibiting low mutation rates also enjoy increased lifespans.”

This illustrates why the theory that mutation accumulation is a key factor in aging remains unproven. Advocates like Ideker reference conditions such as Progeria, wherein individuals age prematurely due to compromised DNA repair mechanisms. Others, including de Magalhães, cite a lack of evidence that simply accumulating mutations is a driver of typical aging, although it does correlate with heightened cancer risk.

Even should DREAM complexes prove instrumental in aging, their multifaceted functions complicate the development of treatments. “Achieving a total loss of DREAM functionality, as we have done, may be too drastic,” advises team member ZANE KOCH from UCSD. “Mildly suppressing DREAM could be the optimal approach for extending lifespans.”