Control of rat H-FABP expression — Reporter gene studies in L6 myoblasts

Heart fatty acid binding protein (H-FABP) is a 14.5 kDa cytosolic protein which facilitates fatty acid solubility and transport. Its concentration in different muscles reflects their fatty acid oxidation capacity, and its expression is stimulated by increased fatty acid fluxes. In order to understand the mechanism of fatty acid-dependent gene expression of the rat H-FABP gene, an everted repeat was identified in its promoter as a potential fatty acid response element, based on its similarity to a previously identified element in an invertebrate FABP gene. Through gelshift analysis specific interaction between nuclear proteins and the everted repeat was demonstrated. Cultured myoblasts were transfected with a series of luciferase reporter genes constructs, and fatty acid induced changes in reporter gene expression were measured. However, since the changes were much smaller than observed with the invertebrate promoter, the reporter gene assay proved to be too insensitive, and unambiguous conclusions were not possible.