Solving The Mystery of Making Insulin

Snapin protein discovery could lead to new Type 2 diabetes treatments

(RxWiki News) Researchers think they have identified what controls the secretion of insulin on a molecular level, a discovery that may improve treating diabetes. A protein called Snapin may be the switch that releases insulin - the hormone that manages blood sugar levels - from the pancreas.

This finding is important for patients with type 2 diabetes, a disease caused by not producing enough insulin or by cells that do not respond to the hormone. After decades of research, Johns Hopkins researchers may have finally identified why diabetics don't produce enough insulin. Using pancreatic cells from mice, they found that Snapin may be the switch that releases insulin from the pancreas.

dailyRx Insight: The Snapin protein discovery is a new direction for Type 2 diabetes research.

In the search for how the pancreas produces insulin, Mehboob Hussain, M.D., associate professor of pediatrics, medicine and biological chemistry at Johns Hopkins University, and colleagues studied how other cells in the body release chemicals. They found that nerve cells used the protein Snapin to release chemicals needed for cells to communicate. Because Snapin is also found in pancreatic cells that release insulin, Hussain's team decided to study the protein further.

To study protein's role in insulin production, the researchers permanently turned on the Snapin gene in the pancreases of a group of mice. Then, they removed pancreatic cells, grew them in a dish for a day, and added glucose (sugar) so that they could measure how much insulin was produced.

According to Hussein, the researchers were surprised to see that the pancreases with Snapin turned on did not have more or larger cells, they simply produced more insulin. More specifically, cells from mice with the Snapin gene turned on made 7.3 billionths of a gram of insulin per cell, compared to 2.8 billionths of a gram per cell in cells from normal mice.

To make sure that Snapin was actually the switch, they reversed their test: they turned off the Snapin gene. The found that normal cells made 5.8 billionths of a gram of insulin per cell while the cells with Snapin turned off made only 1.1 billionths of a gram of insulin. That's about 80 percent less insulin.

In conclusion, Hussein says that even though these results are promising, much more work needs to be done before we can know if the same mechanism will work in humans.

Nearly 26 million individuals are affected by diabetes in the United States each year, with about seven million people going undiagnosed. Diabetes is a chronic metabolic disease with no cure in which a person has high blood sugar because the body does not produce enough insulin (Type 1) or because cells do not respond to the insulin that is produced (Type 2). There are three main types of diabetes: Type 1, Type 2 and Gestational. Several groups of oral drugs, are effective for Type 2, such as Glucophage®, Glucotrol®, and Prandin®, among many others. The therapeutic combination in Type 2 may eventually include injected insulin as symptoms worsen. Along with the presence of physical symptoms, a common blood test known as the A1c can test for the disease.

The study is published in Cell Metabolism.

Review Date: 
March 16, 2011