'Longevity protein' found effective in primates

Chinese scientists have discovered that a "longevity protein" called SIRT6, which regulates aging in rodents, can also affect development in nonhuman primates.

The latest discovery opens new insights into the study and treatment of complex developmental delay disorders and metabolic diseases in humans.

In 1999, scientists who study aging found that the Sirtuin family of genes and their product proteins, which include SIRT6, are linked to longevity in yeast.

In 2012, scientists discovered an abundance of SIRT6 protein can prolong the lifespan of male mice by around 16 percent.

However, SIRT6's effect in advanced mammals such as primates had remained mostly unknown.

To tackle this challenge, Chinese scientists bioengineered the world's first crab-eating macaques with their SIRT6-producing genes removed.

This allowed scientists to directly observe the effect of SIRT6 deficiency in primates.

The results were published online in the scientific journal Nature on Wednesday.

While the macaques lacking SIRT6 did not experience accelerated aging like the rodents, they did show serious birth defects caused by delayed cell growth, such as in brain, muscle and other organ tissues. Macaques that lack the protein usually die hours after birth.

"The effect of SIRT6 deficiency is like turning your biological clock backward by half," said Zhang Weiqi, a researcher from the Chinese Academy of Sciences' Institute of Biophysics and one of the lead scientists behind the discovery.

If the same effect were applied to humans, "it means a fetus could only develop to 5 months old in the mother" despite staying in the uterus the time typically required for development, she said.

Moreover, Zhang and her team discovered that an SIRT6 deficiency in human neural stem cells can jeopardize their proper transformation into neurons. This finding provided further evidence to back a recent discovery made by United States scientists, who reported a loss of function in SIRT6-producing genes in a human fetus can cause it to grow inadequately or die.

"This means SIRT6 is a highly probable candidate for a human longevity protein that can regulate our lifespan and development," Zhang said.

SIRT6 might also be a viable drug target for treating developmental delay disorders, which can lead to a wide range of learning and motor disabilities in children, she said.

For adults and the elderly, SIRT6 might be used to create medicines that target chronic diseases, especially those related to liver or cardiovascular metabolisms, she added. Some studies have also shown SIRT6 might be relevant in treating cancer and neurodegenerative diseases, such as Alzheimer's.

"These will be important future research topics," Zhang said. "A new window of research has now opened for the discovery and research of more human longevity proteins in the future."