Tardigrade protein fortifies human cells

Tardigrades – microscopic creatures that somewhat resemble eight-legged vacuum bags – harbour a unique gene that could help human cells fight radiation, a new study suggests.

The work, published in Nature Communications, will help biologists unravel the secrets of their incredible hardiness.

Tardigrades are perhaps the most robust animals on Earth. With more than 1,000 species known to science, they can withstand temperatures from below freezing to beyond boiling point, endure the pressure of ocean trenches, and survive up to 30 years without food or water.

All tardigrades need water to survive, but their extreme tolerance for dehydration means they can last for decades without water. These micro-animals are durable enough to live in the vacuum of space, if they found themselves in such a situation.

So Takekazu Kunieda at the University of Tokyo and a team in Japan wanted to study the tardigrades’ ability to withstand 1,000 times more radiation than other animals.

To weigh it up, a tardigrade can be exposed to 5,000 grays of radiation and be just fine, while five to 10 grays is fatal to humans.

The team conducted a detailed analysis of the genome of Ramazzottius varieornatus, one of the most stress-tolerant of the tardigrade species.

Comparing tardigrade DNA to that of flies and worms, the researchers predictably found higher numbers of genes associated with stress tolerance.

They also noticed fewer genes usually associated with eliciting stress responses.

Most significantly, though, they discovered a particular protein nicknamed Damage suppressor or Dsup (and the gene that encodes it).

It is believed to be unique to tardigrades, and binds to DNA to help protect cells against the effects of radiation.

This goes some way to explaining the high radiation-tolerance of the species.

The researchers added the Dsup gene to human cells that had been grown under controlled conditions.

Incredibly, the gene and subsequent Dsup protein protected the cells against X-rays, raising interesting questions about the potential use of tardigrade genes in human medicine.

“These findings indicate the relevance of tardigrade-unique proteins to tolerability, and tardigrades could be a bountiful source of new protection genes and mechanisms,” the researchers write.

It’s not a radiation cure-all, though – they acknowledge that adding the Dsup gene to human DNA could well affect cell viability or the way our DNA replicates. More research is also needed to identify other traits in the tardigrade that could help to shield it from radiation-related damage.