A novel hormone dependent acyl-CoA thioesterase involved in the regulation of arachidonic acid release and steroidogenesis.

MALOBERTI PAULA; NEUMAN ISABEL; LISDERO CONSTANZA; FINKIELSTEIN CARLA; MELE PABLO; PAZ CRISTINA; PODEROSO CECILIA; PODESTA, ERNESTO J

Congreso; Biochemistry and Molecular Biology 1999; 1999

We have reported the purification of a phosphoprotein (p43) intermediary in steroid synthesis through arachidonic acid (AA) release. In the present report, we describe the cloning and sequencing of a cDNA encoding p43 and the hormonal regulation of this protein. The protein resulted to be homologous to a very-long-chain acyl-CoA thioesterase. The deduced amino acid sequence of p43 showed consensus sites for phosphorylation by different protein kinases and a lipase serine motif. An increase of p43 mRNA levels was induced by ACTH within 5 min, reaching maximal stimulation (62%) at 15 min, and returning to basal values at 30 min. The transcript of p43 was detected in all stereidogenic tissues and also in heart, liver, and spleen. The biological activity of the cardiac protein was assessed by using an heterologous cell-free assay. Isoproterenol and phenylephrine activate the enzyme in a dose dependent manner (10-8-10-6M). Both propranolol (10-6M) and prazosin (10-6M) block the action of isoproterenol and phenylephrine respectively. Antibodies raised against a synthetic peptide that includes the lipase serine motif and the N-terminal region of p43 block the protein biological activity. Due to the role of the protein in the activation of steroidogenesis through AA release, we propose the name Arachidonic acid-Related Thioesterase Involved in Steroidogenesis (ARTISt) for p43. These results suggest an alternative pathway for AA release in signal transduction.