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Sequencing of 96.7% of the Greenland shark genome revealed changes linked to DNA stability, cellular repair, immunity, and iron control, offering new clues on how this vertebrate can live for centuries and avoid diseases associated with aging
The Greenland shark, the longest-living vertebrate in the world, had 96.7% of its genome sequenced in a study published on May 19 in PNAS, revealing genetic clues about longevity, cancer resistance, and DNA repair.
Greenland shark genome reveals clues about extreme life
The research was conducted by Shigeharu Kinoshita, a fisheries chemist at the University of Tokyo, and colleagues. The study analyzed almost the entire genetic sequence of a little-known species that lives in the North Atlantic and Arctic oceans.
These sharks generally reach between 4 and 5 meters in length and can inhabit depths of up to 2.65 kilometers. Life in cold, deep waters makes observation difficult, making each new genetic information relevant.
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Estimates indicate that the Greenland shark can live about 400 years and only reach maturity around 150 years. This cycle is of interest because it combines slow growth, long survival, and apparent resistance to age-related diseases.
DNA stability appears as a central piece
Among the findings, researchers identified changes in proteins called binding histones, which help coil and compact DNA. These changes involve unique amino acid substitutions and may stabilize chromatin, a structure formed by DNA and proteins in chromosomes.
Kinoshita explained to Live Science that this stability may help reduce the accumulation of DNA damage over an exceptionally long life. In organisms that live for centuries, limiting this cellular wear is a possible biological advantage.
The study also found an expansion of gene families linked to immune responses and DNA repair. For Kinoshita, this result supports the idea that efficient repair and immune regulation are components of longevity and cancer resistance.
Iron control can reduce cellular stress
Another highlighted point was the expansion of ferritin genes, involved in the storage and regulation of iron. This feature suggests a greater ability to control this metabolism and limit oxidative stress, a process capable of damaging DNA and promoting cancer.
The expansion of these genes may also indicate a restriction of ferroptosis, a form of programmed cell death dependent on iron. The set reinforces the hypothesis that extreme longevity depends on several biological systems acting in a coordinated manner.
Kinoshita stated that the analyses indicate greater genomic stability and stress resistance. For him, the long life of the shark does not come from a single gene but from integrated changes in the genome, iron, immunity, and stress.
Discovery still requires functional tests
Dorota Skowronska-Krawczyk, a physiologist and biophysicist at the University of California, Irvine, did not participate in the study but assessed that immunity, DNA repair, chromatin stability, and cancer resistance may help explain the species’ longevity.
She highlighted, however, that functional studies will be necessary to directly test this relationship. The researcher had already shown how DNA repair genes in the retina can help preserve the vision of the Greenland shark.
Aaron MacNeil, a biologist at Dalhousie University in Nova Scotia, also did not participate in the research and considers that the results support the idea of a very long-lived species. Even so, he views the 400-year estimate with caution.
This estimate comes from radiocarbon traces left by Cold War nuclear tests in the sharks’ eye lenses. As they grow in layers, the position of the isotope fixes a temporal reference.
MacNeil notes that the slow mixing of the deep, cold ocean layers may have delayed the arrival of this radiocarbon to the sharks’ environment, raising the estimate. Even so, he states that these animals are at least 200 years old.
