Clues to Why Exercise Helps You Live a Longer, Healthier Life

Researchers at the Howard Hughes Medical Institute have uncovered clues to suggest why living a healthier lifestyle will help you live longer. The answer, they say, is less insulin in the brain.

In their experiments, the researchers sought to understand the role of the insulin-like signaling pathway in extending lifespan. This pathway governs growth and metabolic processes in cells throughout the body. The pathway is activated when insulin and insulin-like growth factor-1 switch on proteins inside the cell called insulin receptor substrates (Irs).

In earlier work, the researchers had found that knocking out both copies of one of the Irs genes, Irs2, in mice reduces brain growth and produces diabetes due to pancreatic beta cell failure. However, in the new study, when the researchers knocked out only one copy of the gene, they found the mice lived 18 percent longer than normal mice.

Because reducing insulin-like signaling in the neurons of roundworms and fruitflies extends their lifespan, the researchers decided to examine what would happen when they knocked out one or both copies of the Irs2 gene only in the brains of mice.

Mice lacking one copy of the Irs2 gene in brain cells also showed an 18 percent longer lifespan, and the near complete deletion of brain Irs2 had a similar effect. “What's more, the animals lived longer, even though they had characteristics that should shorten their lives—such as being overweight and having higher insulin levels in the blood,” said Morris F. White, an investigator for HHMI.

However, both sets of Irs2 knockout mice exhibited other characteristics that marked them as healthier, said White. They were more active as they aged, and their glucose metabolism resembled that of younger mice. The researchers also found that after eating, their brains showed higher levels of superoxide dismutase, an antioxidant enzyme that protects cells from damage by highly reactive chemicals called free radicals.

White and his colleagues are planning their next studies to better understand how healthy aging and lifespan are coordinated by Irs2 signaling pathways in the body and the brain. White speculated that the insulin-like signaling pathway in the brain might promote age-related brain diseases.

Personally, I'll be most interested in seeing how this work meshes with the work being done on Sirtuin. Calorie Restriction methods have not been shown to be effective in humans yet, but there's no reason to think that they won't be. The research on brain insulin, on the other hand, is something that will have to be watched fairly closely. While mice may make an interesting model for early-stage testing, their brains are not that similar to ours and any type of alteration being done on the brain could have effects that would not be obvious in a mouse model.

New Promise for Diabetes Treatment Using Stem Cells

A new research study treated fifteen young diabetics in Brazil, all suffering from Type I diabetes, with stem cells drawn from their own blood. Though too early to call it a cure, the procedure has enabled thirteen of the young people, who have Type I diabetes, to live insulin-free so far, some as long as three years.

"It's the first time in the history of Type 1 diabetes where people have gone with no treatment whatsoever ... no medications at all, with normal blood sugars," said study co-author Dr. Richard Burt of Northwestern University's medical school in Chicago.

While the procedure can be potentially life-threatening, none of the 15 patients in the study died or suffered lasting side effects. But it didn't work for two of them.

Larger, more rigorous studies are needed to determine if stem cell transplants could become standard treatment for people with the disease once called juvenile diabetes. It is less common than Type 2 diabetes, which is associated with obesity.

Read the full article by AP Medical Writer Lindsey Tanner here.

MIT and Novartis Make Diabetes Genetic Info Freely Available

The Broad Institute at MIT, Novartis, and Lund University have publicly released the results of a genome-wide map of genetic differences in humans and their relationship to type 2 diabetes and other metabolic disorders.

The work is the result of a pioneering public-private collaboration known as the Diabetes Genetics Initiative (DGI), which was formed in 2004 and is aimed at deciphering the genetic causes of type 2 diabetes. The collaboration brings together diverse expertise in diabetes and metabolic disease, human genetics, genomics, statistical analysis, and drug development.

The results of the study are freely available online at www.broad.mit.edu/diabetes.

First, let me start by saying I'm pretty much a die-hard capitalist, and I believe that profit is an excellent motivator for companies in performing research and development. But I don't think that anybody should be allowed to profit off of human suffering, so that's why I'm really happy when I see something like this. A for-profit company (Novartis) has put forth their resources to help find better ways to treat or even cure a disease that affects more than 170 million people world-wide (including several people that I know personally).