One way obesity causes diabetes is by changing the production of proteins that influence how other proteins are put together. This process can cause extra fat to be made in the liver, which is known to be a major cause of insulin resistance - a condition in which the hormone insulin becomes less effective at controlling blood sugars.
"Watch your weight to avoid diabetes."
This research shows how obesity increases the risk of insulin resistance and diabetes, says Mary-Elizabeth Patti, M.D., from Joslin Diabetes Center and Harvard Medical School and leader of the study.
It is already known that obesity is the main cause of diabetes worldwide. These findings - which are published in Cell Metabolism - show a new way in which excess weight leads to insulin resistance.
After looking at the levels of proteins in the livers of obese people, Dr. Patti and her colleagues found a drop in the number certain proteins that control RNA splicing - a process that affects how other proteins are put together.
As Dr. Patti explains, this decrease in protein production changes how other proteins work, causing excess fat to be made in the liver. This excess fat, she says, is known to lead to insulin resistance.
After making this general finding, Dr. Patti and colleagues went on to study an example of one of these RNA-splicing proteins (called SFRS10). Levels of SFRS10 go down in the muscle and liver of both obese people and overweight mice.
The researchers studied both human cells and mice. They found that SFRS10 helps control a certain protein called LPIN1, which is important in the making of fat.
According to Dr. Patti, these findings should encourage other researchers to look for other genes for which differences in splicing may raise the risk of type 2 diabetes. She adds that the eventual hope is that drug treatments can change how these genes are spliced, and thus limit some of the harmful effects of obesity.