The Washington University School of Medicine researchers said their finding might someday help people avoid age-related problems such as diabetes and even some cancers.
   The research team bred large numbers of mice, half of which were genetically engineered to make more of a protein in their muscle tissue called uncoupling protein-1. In muscle tissue, uncoupling protein-1 converts energy from food into heat and mimics the effects of exercise.

   The scientists, led by Dr. Clay Semenkovich, a professor of endocrinology, metabolism and lipid research, found mice with extra uncoupling protein-1 in their muscle tissue were more likely to live longer, presumably because they were able to avoid age-related diseases such as diabetes and obesity.

   "We were a little bit disappointed because we had hoped uncoupling in muscle would slow aging, but maximum lifespan didn't increase," Semenkovich said. "However, the odds of reaching maximum lifespan did improve in the uncoupled mice."

   The study, which included former postdoctoral fellows Alison Gates and Sharon Chinault and Dr. Carlos Bernal-Mazrachi, appears in the December issue of the journal Cell Metabolism.