According to a new study, researchers from Brown University have identified an enzyme that appears the regulate the physiology of both fat types in mice, decreasing inflammation in white fat tissue, while promoting the ability of brown fat to burn calories. New study in mice and humans suggests that an enzyme called SNRK suppresses inflammation in obesity-related 'white fat' while increasing metabolism in heat-producing 'brown fat,' making SNRK an intriguing target in the battle against obesity.
The human body has two primary kinds of white fat, which stores excess calories and is associated with obesity, and brown fat, which burns calories to produce heat and has garnered interest as a potential means of combating obesity. Simin Liu said, "Reducing inflammation in white fat may ease associated complications such as insulin resistance, while at the same time, increasing brown fat metabolism may aid in weight loss."
The presence of SNRK in fat tissue was first discovered by co-corresponding author Haiyan Xu while she was a researcher in the Molecular Epidemiology and Nutrition Lab of Brown's Center for Global Cardiometabolic Health. Her initial research suggested that the enzyme played a role in regulating inflammation, but this latest study was designed to get a more complete picture of its function in fat tissue.
Inflammation and metabolism
For this new study, the researchers bred mice that lack the gene for producing SNRK in fat cells. They could then compare fat tissue from those mice with tissue from normal mice. The study showed that mice lacking the SNRK gene had a significantly higher concentration of macrophages in white fat tissue compared with normal mice.
Macrophages are immune cells commonly used as markers for inflammation, and their increased presence helps confirm that SNRK plays a role in regulating inflammation in white fat tissue. In previous research have shown that inflammation in white fat is associated with insulin resistance, a risk factor for the development of diabetes.
In addition to its effects on white fat, the researchers showed that SNRK influences the physiology of brown fat tissue. Mice lacking the SNRK gene tended to be heavier than normal mice, and were shown to have lower overall metabolic rates. The SNRK-lacking mice maintained their extra weight even when treated with a drug known to induce weight loss in rodents by activating brown fat.
Function in humans
Having established that SNRK appears to regulate fat tissue inflammation and metabolism in mice, the researchers took a step further investigating whether SNRK may play a similar role in humans. The team identified multiple germline mutations in the human genes responsible for SNRK production that were directly associated with higher body mass index, higher waist circumference and risk of obesity in a cohort of 12,000 women who participated in the Women's Health Initiative.
Liu concludes, they hope in making connection could fasten the process of multidisciplinary collaborations in translating lab-based discoveries to new therapies or targets for interventions.