Scientists discover a potential new cause of diabetes

An enzyme that blocks insulin produced in the body could be a new target to treat diabetes, according to scientists at Case Western Reserve University and University Hospitals.

Their study, published the journal Cell, focuses on nitric oxide, a compound that dilates blood vessels, improves memory, fights infection and stimulates the release of hormones, among other functions. How nitric oxide performs these activities had long been a mystery.

From this study, the team of academics have detected a new “carrier” enzyme called SNO-CoA-assisted nitrosylase.

Otherwise known as SCAN, the enzyme attaches nitric oxide to proteins, including the receptor for insulin action.

Mouse models without the SCAN enzyme appeared to be shielded from diabetes, suggesting that too much nitric oxide on proteins may be a cause of such diseases.

Lead researcher Jonathan Stamler said: “We show that blocking this enzyme protects from diabetes, but the implications extend to many diseases likely caused by novel enzymes that add nitric oxide. Blocking this enzyme may offer a new treatment.”

Many human diseases, including Alzheimer’s, cancer, heart failure and diabetes, are thought to be caused or accelerated by nitric oxide binding excessively to key proteins. With this discovery, Stamler said, enzymes that attach the nitric oxide become a focus.

With diabetes, the body often stops responding normally to insulin. The resulting increased blood sugar stays in the bloodstream and, over time, can cause serious health problems.

Individuals with diabetes, the Centers for Disease Control reports, are more likely to suffer such conditions as heart disease, vision loss and kidney disease. But the reason that insulin stops working isn’t well understood.

Excessive nitric oxide has been implicated in many diseases, but the ability to treat has been limited because the molecule is reactive and can’t be targeted specifically, Stamler said.

“This paper shows that dedicated enzymes mediate the many effects of nitric oxide,” he said. “Here, we discover an enzyme that puts nitric oxide on the insulin receptor to control insulin.

“Too much enzyme activity causes diabetes. But a case is made for many enzymes putting nitric oxide on many proteins, and, thus, new treatments for many diseases.”

Click here to read the study.