Tyrosine Phosphates Act on Steroidogenesis Through the Activation of Araquidonic Acid Release

FERNANDA CASTILLO, FLORENCIA CANO, PAULA MALOBERTI, ROCÍO CASTILLA, ISABEL NEUMAN, CECILIA PODEROSO, CRISTINA PAZ, ERNESTO J. PODESTA´,AND FABIANA CORNEJO MACIEL*

Nueva Orleans, EEUU

Congreso; XI Adrenal Cortex Conference; 2004

The ACTH signaling pathway includes both PKA activation as well as PKA dependent  tyrosine phosphatase activation. In addition, the action of this hormone also  includes the regulation of the intracellular levels of arachidonic acid (AA) by the  concerted action of two enzymes: an acylCoA-thioesterase and an acyl-CoAsynthetase  (ACS4). This work describes the production and characterization of a  specific ACS4 antibody, which was used to analyze the effect of ACTH on ACS4  protein level in Y1 adrenocortical cells and the putative relationship between tyrosine  phosphatases and ACS4. The antiserum was obtained from rabbits immunized with  the recombinant ACS4. This immunogen was produced in bacteria and eluted from an  acrylamide gel after SDS-PAGE separation of a partially purified bacteria lysate.  When used in Western blot analysis, the antibody obtained specifically recognized  only one protein of the molecular mass corresponding to ACS4, in Y1 cells and in  several rat tissues. Using the antibody described here, we analyzed the effect of ACTH  stimulation on ACS4 protein level. The hormone produced an increase of this acyl-  CoA synthetase in Y1 adrenocortical cells. Moreover, this effect was mimicked by  cAMP and partially reduced by a tyrosine phosphatase inhibitor. We propose that  ACTH regulates ACS4 protein levels through a PKA-dependent mechanism that could  involve also PTP activity.