September 4, 2013Image Credit: SSokolov / Shutterstock

redOrbit Staff & Wire Reports – Your Universe Online

Researchers from the Washington University School of Medicine in St. Louis have reportedly discovered the mechanism through which a specific type of protein can bring about a “significant delay” in the aging process.

Writing in the September 3 issue of the journal Cell Metabolism, the study authors explain how one sirtuin protein (a class of proteins that have been linked to cellular processes like aging, transcription, apoptosis, inflammation and energy efficiency) known as Sirt1 can increase longevity.

Sirt1 operates in the brain, prompting neural activity in certain regions of the hypothalamus. That neural activity results in drastic physical changes in skeletal muscle, as well as increases vigor and longevity, according to Shin-ichiro Imai, an associate professor in the university’s Departments of Developmental Biology and Internal Medicine, and his colleagues.

“In our studies of mice that express Sirt1 in the brain, we found that the skeletal muscular structures of old mice resemble young muscle tissue. Twenty-month-old mice (the equivalent of 70-year-old humans) look as active as five-month-olds,” Imai explained in a statement.

He and his associates set out to explore the link between dietary restrictions (i.e. a low-calorie diet) and longevity, knowing from previous research that the Sirt1 protein had an impact on delaying the aging process when caloric intake was restricted. They hoped to discover the exact process through which this function was carried out.

The researchers studied mice which had been genetically modified to overproduce the protein. Some of the rodents had been engineered to overproduce Sirt1 in body tissues, while others were engineered to produce more of it only in the brain. Imai found that only those which overexpressed Sirt1 in the brain (known as BRASTO) had “significant lifespan extension and delay in aging, just like normal mice reared under dietary restriction regimens.”

In fact, the BRASTO mice demonstrated significant lifespan extension without any related dietary restrictions, the study authors said. Positive skeletal muscle changes were observed in these mice, as well as an increased level of nocturnal physical activity, body temperature and oxygen consumption in comparison with age-matched control subjects. The BRASTO mice also experienced better or deeper sleep, they added.

“The median life span of BRASTO mice in the study was extended by 16 percent for females and 9 percent for males,” the university said. When translated to people, that could result in an additional 13 to 14 years for women and an additional seven years for men, increasing the lifespan of females to the high 90s and males to the mid-80s.

The authors also reported a delay in cancer-dependent death in the BRASTO mice versus the control mice. “What we have observed in BRASTO mice is a delay in the time when age-related decline begins, so while the rate of aging does not change, aging and the risk of cancer has been postponed,” Imai added.