Rajan Sah, MD, PhD, assistant professor of internal medicine in the UI Carver College of Medicine, has received a three-year, $400,000 Carver Trust Young Investigator award to study the role of fat-cell expansion in the development of insulin resistance and diabetes.

"Fat cells, or adipocytes, are notorious for their tremendous ability to expand and grow. A fat cell can increase its surface area by more than tenfold and volume by more than 30 times in the setting of obesity," says Sah, who also is a member of the Fraternal Order of Eagles Diabetes Research Center and the Abboud Cardiovascular Research Center.

This raises some interesting questions about the biology of fat cells: What are the mechanisms that permit such remarkable expansion of fat cells? Do fat cells have cellular “stretch” sensors that respond to changes in cell size? And can diabetes or insulin resistance arise from “overstretching” of fat cells?

Sah and his team have recently discovered a novel stretch/swell-activated ion channel in mouse and human fat cells. In immune cells, this channel activates a signaling pathway important for development. The same signaling pathway in fat cells controls glucose uptake and cellular fat accumulation.

Sah will use the Carver Trust funding to study the new idea that this ion channel—called SWELL1—connects sensing of adipocyte size with regulation of fat metabolism. Understanding the basic biology of fat storage might help researchers identify new therapeutic targets for the prevention of obesity and associated diseases like diabetes.