Scientists close in on trigger of insulin ...( bound to proteins but that increase ca...)

Looking for proteins in the insulin-signaling pathway that were more glycosylated than normal, Vosseller and Wells found two: beta-catenin and insulin receptor substrate-1 (IRS-1). The crucial role these proteins play in passing along insulin's messages is likely to be adversely affected by the extra sugars they carry, the researchers say.

"Our experiments show that increasing O-GlcNAc on proteins is, by itself, a cause of insulin resistance, rather than an effect or a coincidence," says Vosseller.

In the body, sugar (glucose) is changed into glucosamine, which is changed into O-GlcNAc. Other scientists have shown that giving cells or animals excessive amounts of sugar or glucosamine, along with extra insulin, leads to insulin resistance. The new findings provide an explanation for others' experience with animal and laboratory models of insulin resistance.

There has been little study of glucosamine, a commonly used dietary supplement, in people. It is suggested that people taking glucosamine consult their doctors if they are concerned about the possibility of increasing their risk of developing diabetes.

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Contact: Joanna Downer
jdowner1@jhmi.edu
410-614-5105
Johns Hopkins Medical Institutions
15-Apr-2002