Hormone-dependent phosphorylation of Acyl-CoA synthetase 4 (Acsl4) in steroidogenic cells

CASTILLA R, SMITH, E, CASTILLO AF, PODEROSO C, PODESTÁ EJ

San Miguel de Tucuma, Tucuman, Argentina

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular (SAIB); 2009

SAIB

Steroid synthesis is modulated by different hormones or factors through PKA or PKC-mediated protein phosphorylation. Acsl4, whose substrate is Arachidonic Acid (AA), is a key enzyme in steroid synthesis. We previously described that Acsl4 and Acyl- CoA thioesterase I (Acot2) regulate the intracellular levels of AA and steroidogenesis in a concerted manner. Since Acsl4 aminoacidic sequence shows phosphorylation consensus sites for PKA and PKC, the aim of this study was to determine whether Acsl4 is substrate of these kinases. Recombinant Acsl4 results to be suitable substrate for PKA and PKC kinase. Then, we studied A csl4 phosphorylation in YI adrenal cells. By  32P[H2PO4) incorporation, immunoprecipitation, two-dimensional gel electrophoresis, autorradigraphy and westem-blot we demonstrated that ACTH regulates the phosphorylation of Acsl4.  We demonstrate for the first time that A sl4 is a phosphoprotein and that this phosphorylation is hormone regulated.