Gene defect that blocks insulin release in mice may cause Type 2 diabetes

A faulty gene in mice may predispose some people with the same genetic defect to Type 2 diabetes, researchers at the University of Illinois at Chicago College of Medicine have found.

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In a study appearing in the journal Diabetes, UIC's Bellur Prabhakar and colleagues discovered that a malfunctioning gene called MADD prevents insulin from being released into the bloodstream to regulate blood sugar levels.

In previous studies, slight genetic variations in MADD were shown to be strongly associated with Type 2 diabetes among European and Han Chinese test subjects. The MADD gene has also been implicated in certain cancers.

"Without the gene, insulin can't leave the beta cells, and blood glucose levels are chronically high," Prabhakar said in a statement.

Bellur Prabhakar, professor and head of microbiology and immunology--Courtesy of UIC

Prabhakar and his team developed a mouse model in which the MADD gene was deleted from the insulin-producing beta cells in order to study the gene's role in diabetes. In a healthy person, beta cells in the pancreas help to store and release insulin in response to increased blood glucose levels that result from eating. People with Type 2 diabetes don't produce enough insulin or are resistant to insulin. Insulin helps glucose enter the cells, where it can be used as energy--a regulating method that keeps glucose levels in the blood in check.

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The genetically altered mice all had elevated blood glucose levels, which was caused by insufficient release of insulin. The team believes the findings show that Type 2 diabetes can be directly caused by the loss of a properly functioning MADD gene alone.

Prabhakar and his team next plan to investigate the effect of a drug that promotes the secretion of insulin in MADD-deficient beta cells.

"If this drug works to reverse the deficits associated with a defective MADD gene in the beta cells of our model mice, it may have potential for treating people with this mutation who have an insulin-secretion defect and/or Type 2 diabetes," he said.

- see the study abstract
- read the press release