With a maximum lifespan of over 200 years, the bowhead whale lives longer than any other mammal. But how the 80-ton beasts survive for so long has never been fully explained.
Now scientists have found a hint of the answer and are developing plans to test whether the same biological trick can be performed on humans. If so, it offers hope for accelerating healthy aging and protecting organs and tissues during surgery and transplantation, they say.
“We sought to understand the mechanisms behind the exceptional longevity of the bowhead whale, the world's longest-living mammal,” said Professor Vera Gorbunova, a biologist at the University of Rochester in New York. “We found that perhaps part of this mechanism is very precise and efficient repair of DNA breaks.”
All living organisms suffer from DNA damage during their lives. Cells try to repair the damage, but repairs are not always effective. This causes mutations to accumulate over time, which can increase the risk of cancer and accelerate aging by impairing the functioning of cells and tissues.
Gorbunova and her colleagues found that bowhead whales are particularly good at repairing DNA damage in which both strands of the DNA double helix are broken. As a result, whales acquired fewer mutations. “We have found that these types of repairs are very important for longevity,” she said.
In a series of experiments on whale cells, they showed that DNA repair is enhanced by the protein CIRBP, which is activated when exposed to cold. Bowhead whales spend their lives in Arctic waters and produce 100 times more CIRBP than humans.
“This strategy, which does not destroy damaged cells but faithfully repairs them, may contribute to the exceptional longevity and low incidence of cancer in bowhead whales,” researchers wrote in Nature.
The team went on to investigate what happened when they increased the levels of CIRBP in human cells. Increasing the amount of protein doubled the proportion of double-strand breaks that repaired cells. Further experiments on flies showed that the extra CIRBP increased their lifespan and made them more resistant to mutation-causing radiation.
“The very first conclusion we can draw is that people have room for improvement,” Gorbunova said. “People used to think that we couldn’t improve DNA repair, that it was already optimal, but the whale does it better than us.”
How big a role DNA repair plays in bowhead whale lifespan is unclear, but researchers are now raising mice with elevated levels of CIRBP to see how long they live. They also hope to test whether protein levels increased in cold-water swimmers or those taking cold showers, and how durable the increase might be.
“We need to see if short-term exposure to cold is enough, but we will also look for pharmacological ways to achieve this,” Gorbunova said. “Not everyone wants to swim in cold water.”
Professor Gabriel Balmus, who studies DNA damage and repair at the UK Dementia Research Institute at the University of Cambridge, said: “Increasing the ability of our cells to repair DNA could, in principle, slow aging and associated disease processes – an idea supported by evidence from other species, where stronger repair correlates with longer lifespan. However, translating this to humans will be far from simple, requiring a balance between resilience and the body's natural limits on renewal.”
