Transcriptional regulation of muscle fatty acid-binding protein.

Heart fatty acid-binding protein (H-FABP) is present in a wide variety of tissues but is found in the highest concentration in cardiac and red skeletal muscle. It has been proposed that the expression of H-FABP correlates directly with the fatty acid-oxidative capacity of the tissue. In the present study, the expression of H-FABP was measured in red and white skeletal muscle under two conditions in which fatty acid utilization is known to be increased: streptozotocin-induced diabetes and fasting. Protein concentration, mRNA concentration and transcription rate were measured under both conditions. The level of both protein and mRNA increased approximately 2-fold under each condition. The transcription rate was higher in red skeletal muscle than in white muscle, was increased 2-fold during fasting, but was unchanged by streptozotocin-induced diabetes. In addition to supporting the hypothesis that H-FABP is induced during conditions of increased fatty acid utilization, these findings demonstrate that the regulation of H-FABP expression may or may not be at the level of transcription depending on the stimulus.