Bowhead Whales Can Live Up to 200 Years and Their DNA May Contain the Longevity Secret

The Earth’s longest-living creatures are members of the sponge family, with some specimens having lived since the Neolithic Revolution. The bowhead whale (Balaena mysticetus) may be positively spritely in comparison, but the cetacean still earns the distinction of being the world’s longest-living mammal, with individuals known to reach their 200th birthday and beyond.

This is, in part, thanks to their impressive capacity to avoid age-related disease. Now, researchers have identified a DNA-repair protein that could explain how they do so — and one day help us to, too.

Writing in the journal Nature, researchers at the University of Rochester point to high levels of CIRBP, a protein that repairs double-strand breaks in DNA and can lead to disease if not effectively managed.

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The Bowhead Whale Is a Large Conundrum

The bowhead whale is not only spectacularly long-lived — it is also one of the world’s heaviest mammals, weighing nearly 18,000 pounds. This is puzzling because it could be expected that animals with a larger body size are more vulnerable to cancer. After all, big animals carry more cells that have the potential to become malignant.

This is Peto’s Paradox. On the basis that larger species do not seem to have a higher risk of developing cancer than their smaller counterparts, it suggests that those larger animals must have additional mechanisms that protect them against malignant cells, either through prevention or by repairing harmful mutations.

Examining Bowhead Whale Cells

In this study, the team examined the number of hits required for a bowhead whale’s cells to become cancerous. Specifically, they looked at fibroblasts — a type of cell responsible for the formation of connective tissue.

Their reasoning was based on the “multi-stage model of cancer” that supposes normal cells become cancerous after a certain number of genetic mutations (or oncogenic hits). In a surprising twist, the fibroblasts of bowhead whales require fewer hits than those of humans to turn malignant.

Instead of relying on tumor suppressor genes, the whale appears able to repair damaged DNA with the help of various proteins. The researchers note several of these appeared at elevated levels in bowhead whales compared to other mammal species, but levels of CIRBP were particularly significant and appeared “at 100-fold higher levels,” Vera Gorbunova, a professor of biology at the University of Rochester, explained in a statement.

The repair-boosting properties of CIRBP appeared to be confirmed when Gorbunova added the protein to the cells of fruit flies. The intervention extended the lifespan of fruit flies and offered the insects greater resistance to irradiation. Adding CIRBP to human cell cultures also appeared to enhance DNA repair.

The researchers write: “This strategy, which does not eliminate damaged cells but faithfully repairs them, may be contributing to the exceptional longevity and low cancer incidence in the bowhead whale.”

This, they say, suggests tumor suppression is not the only answer to Peto’s paradox.

Learning From the Bowhead Whale

The team now plans to increase their understanding of CIRBP and in particular, the mechanism by which it boosts DNA repair with the hope that one day it could help humans avoid cancer and other diseases.

One particularly intriguing discovery is that decreasing the temperature appears to ramp up CIRBP production. The researchers are already considering ways to increase levels of the proteins in humans, whether by medical means or through lifestyle changes such as cold showers.

“This research shows it is possible to live longer than the typical human lifespan,” said Gorbunova.

“By studying the only warm-blooded mammal that outlives humans, our work provides information about the mechanisms that allow such extended lifespans, underscoring the importance of genome maintenance for longevity.”

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Article Sources:

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• This article references information from the recent study published in Nature: Evidence for improved DNA repair in long-lived bowhead whale