The Tardigrade Protein Now Being Tested in Mice

In 2016, Takuma Hashimoto and colleagues sequenced the genome of Ramazzottius varieornatus — one of the toughest tardigrades known — and found a small nuclear protein nothing else on Earth seems to have. They called it Dsup, for damage suppressor. When they put the gene into cultured human kidney cells and zapped them with X-rays, the cells came out with about half the DNA breaks they should have had.

The protein doesn't repair damage. It prevents it. Later structural work in eLife in 2019 showed Dsup wraps directly around the nucleosome — the spool that DNA winds around — and physically blocks the hydroxyl radicals that ionizing radiation produces in water. Less radical, less break.

The tardigrade itself can survive doses around 5,000 grays of gamma rays. A human dies somewhere between 5 and 10. So the obvious question — can Dsup do anything for humans? — has been hanging over the field for a decade.

In February 2025, a team led by Giovanni Traverso at MIT and James Byrne at Iowa published the first serious answer in Nature Biomedical Engineering. They packaged the Dsup gene as messenger RNA, delivered it to mice with lipid nanoparticles, and irradiated the tissue. Double-strand breaks dropped roughly 50 percent. The protein cleared in days, which is what you want — a temporary shield around healthy tissue while a tumor takes the full dose.

It is a long way from a mouse to a clinic. But the strangest thing about Dsup may be that the trick is portable at all.