Obesity is a global health problem that affects more than 40% of adults in the United States. It is associated with increased risk of various chronic diseases, such as diabetes, cardiovascular disease and cancer. Obesity is also linked to intrinsic metabolic abnormalities that impair the ability of fat cells to burn energy, making weight loss more difficult. But how does obesity cause these metabolic changes? A new study published in Nature Metabolism sheds some light on this question.
The study, led by researchers from University of California San Diego School of Medicine, focused on the mitochondria, the energy-producing structures of the cells. Mitochondria are essential for burning fat and maintaining metabolic health. The researchers found that when mice were fed a high-fat diet, mitochondria within their fat cells broke apart into smaller mitochondria with reduced capacity for burning fat. This process, called mitochondrial fragmentation, resulted in weight gain and metabolic dysfunction in the mice.
The researchers also discovered that mitochondrial fragmentation is controlled by a single gene, called RaIA. RaIA is normally activated by stress signals, such as inflammation or nutrient overload. When RaIA is overactive, it interferes with the normal functioning of mitochondria, triggering the metabolic issues associated with obesity. The researchers were able to reverse this effect by deleting RaIA from the mice, which protected them from excess weight gain and improved their metabolic health, even when they ate the same high-fat diet as other mice.
The study suggests that RaIA is a key molecule that mediates the transition from healthy weight to obesity. It also provides a potential target for obesity treatment and prevention strategies. By inhibiting RaIA activity, it may be possible to restore mitochondrial function and enhance fat burning in obese individuals. The researchers plan to further investigate the role of RaIA in human obesity and test whether pharmacological inhibitors of RaIA can have beneficial effects in animal models and clinical trials.