French researchers have discovered two proteins that appear to have a major influence on metabolism and weight regulation. Studies on genetically engineered mice have shown that TIF2 and SRC-1 act on the same receptor but have completely opposite effects. Dr Johan Auwerx, and colleagues at the Institut de Genetique et de Biologie Moleculaire et Cellulaire and the Institut Clinique de la Souris, found that mice bred to have no copies of the TIF2 gene did not put on weight when fed a high-fat diet, whereas those with the normal two copies of the gene became fat. Furthermore, those without TIF2 had faster metabolisms and lower fasting blood sugar. When the experiments were repeated with the SRC-1 gene, results showed that mice without SRC-1 tended to have slower metabolisms and be more prone to obesity than mice with the gene. Further experiments on normal mice fed a high-fat diet, revealed that as the mice ate more fat levels of TIF2 rose while those of SRC-1 remained roughly the same. Together, the results suggest that in the absence of TIF2, SRC-1 stimulates energy expenditure and thus the burning of body fat. Auxerx believes that a medication that boosts the activity of SRC-1 could offer protection against type II diabetes and obesity.
SOURCE/REFERENCE: Cell 2002; 111:931-941
