Protein sensor molecule discovered

A Chiba University, Japan, research team has discovered a protein sensor molecule that is closely related to the secretion of insulin from the beta cells of the pancreas, which they claim has important implications for the development of new diabetes treatments.

During eating the digestive tract releases large volumes of a certain hormone that promotes digestion; one response is that cyclic AMP (cAMP), a messenger molecule that plays a key regulatory role in many types of cells, increases inside the beta cells of the pancreas.

The university group discovered a type of sensor protein inside the beta cells that detects this increase in cAMP and responds by binding to a known calcium ion sensor protein that normally signals the end of insulin secretion, and insulin is released from the beta cells.

In animal experiments, the researchers engineered mice so their beta cells could not produce this cAMP sensor protein. Such mice produced less than half the normal amount of insulin. The experiments suggest that the secretion of insulin from the pancreas is suppressed when this protein is lacking, which points to a potentially new treatment for diabetes.

Not all diabetics respond to the current forms of therapy, by which glucose promotes the release of insulin from the beta cells of the pancreas. The discovery of the cAMP sensor protein suggests an alternate strategy based on a different mechanism for treatment of diabetics who do not respond to conventional therapy.

According to a survey by the Health and Welfare Ministry, about 7 million diabetics are registered in Japan, including one in 10 over the age of 40. More-over, the rate of incidence is accelerating, and the number could reach 10 million by 2003.