By better understanding the biological underpinnings of different types of fat in the body, scientists hope to uncover new ways to tackle obesity and conditions relating to it. Researchers have now found that increasing levels of a certain protein in brown fat could offer protection against diabetes in at-risk individuals, by altering the behavior of white fat cells.
White fat is the type of fat that forms love handles and beer bellies, storing most of the body's excess energy in flabby tissues. Brown fat, on the other hand, burns calories to keep the body warm in the cold. There is considerable interest in promoting brown fat formation instead of white fat as a way of helping folks shed weight, but the authors of this new study have focused on how it might also safeguard against the development of type 2 diabetes.
Carried out at the University of Texas Southwestern Medical Center, the research focuses on a protein called perilipin 5 (PLIN5), which coats lipid droplets inside cells, especially those of the brown fat variety. The scientists explored its role by carrying out experiments on mice that had been genetically engineered to possess high levels of PLIN5 in their brown fat tissue, and observing the effects.
A large percentage of type 2 diabetes is driven by obesity, and the hallmarks of this condition include high blood-sugar levels, a resistance to insulin that helps the body process glucose, and fatty liver disease. The genetically engineered mice showed good signs in all these areas, with significantly lower blood sugar, higher insulin sensitivity and less fatty livers than a control group of mice with regular PLIN5 levels.
Through further investigations, the team zeroed in on the reasons behind these effects. Part of this related to changes in the mitochondria of the brown fat tissue, which they found had adapted to burn greater amounts of fat at room temperature, as if the animals had been placed in the cold. But the scientists also found that white fat cells in the engineered mice had shrunk in size and showed signs of reduced inflammation, both hallmarks of improved insulin sensitivity and ability to process sugar.
“By taking advantage of this natural system, we may be able to help make fat depots more metabolically healthy and potentially prevent or treat obesity-associated diabetes,” says study leader Perry E. Bickel.
The findings are promising for better understanding how obesity drives type 2 diabetes and similar conditions, and offers a new potential target for treatment. There is still plenty of work to do, however, and not just in trying to translate the results from mice to humans, but understanding how the brown fat confers these downstream changes in white fat. The scientists say one possibility is that it sends some sort of molecular factor through the bloodstream.
“The next question we want to address,” says Bickel, “is what that factor is and whether we can harness it for therapeutic benefit.”
The research was published in the journal Nature Communications.