Scientists have sequenced the genome of a strange little creature, the naked mole rat. Why? Because it never gets cancer, lives an unbelievably long life without mental decline, and has many other amazing powers that may hold clues for human health.
Mole rats are hairless, buck-toothed rodents four inches long that live in underground colonies in arid sections of Kenya, Ethiopia, Somalia and Eritrea. Their social structure is the mammalian equivalent of an ant colony. There’s a queen who takes two or three male consorts and is the only female to reproduce. She lords over the rest of the realm — which can be as large as 200 animals — so that the other females cease ovulating and the males give up.
Mole rats can survive in environments low in oxygen (as little as 8 percent as opposed to 21 percent in the atmosphere) and laden with ammonia and carbon dioxide. Unlike other mammals (but like reptiles), they have a hard time regulating their body temperature. They have to move toward the warmer upper reaches of the burrow or huddle with their brethren when they get cold.
But their most unusual features are extreme longevity and apparently complete resistance to developing cancer.
Naked mole rats can live more than 25 years; mice live about four. Buffenstein said she has never found a malignant tumor in a mole rat in her 30-year-old colony, which has 2,000 animals. In a recent experiment, a group of mole rats had patches of skin painted with a chemical carcinogen at a dose 1,000 times stronger than what causes skin cancer in mice. None developed tumors.
A study published in 2009 found that naked mole rats had a molecular anticancer mechanism not present in mice or people. But a first look at the species’ full complement of 22,561 genes shows that’s just the beginning.
There are changes in genes involved in maintaining telomeres, the “tails” of chromosomes that determine how long a cell lives. There are changes in genes involved in marking damaged proteins for destruction. There’s an increase in “chaperone” genes that keep proteins folded into their right shapes. There are genes that appear to let the animals maintain stem cells in their tissues longer than other rodents.
The study looked at 54 human brain genes that become less or more active as a person ages. In the mole rat, 30 of those genes remain stable throughout life, and two others change their activity in a direction opposite to what occurs in human brains.
Mole rats have 96 gene families unique to the species. Interestingly, they and humans also share 178 gene families that neither mice nor other rats have.