Cloning and sequencing of an acth-regulated phosphoprotein intermediary in the regulation of arachidonic acid release and steroidogenensis

FINKIELSTEIN CARLA; MALOBERTI PAULA; MENDEZ CARLOS F; PAZ CRISTINA; CORNEJO MACIEL, FABIANA; CYMERYNG CORA; NEUMAN MARÍA ISABEL; DADA LAURA; MELE PABLO; SOLANO ANGELA; PODESTA ERNESTO JORGE

Congreso; X International Congress on Hormonal Steroids; 1998

We have previously reported the purification of a phosphoprotein (p43) intermediary in steroid synthesis through the arachidonic acid (AA) release. Here, we describe the cloning and sequencing of a cDNA encoding p43 as well as the hormonal regulation of the p43 transcript. The deduced aminoacid sequence of p43 shows consensus sites for phosphorylation by different protein kinases, and a lipase serine motif. Antibodies raised against a synthetic peptide that includes the lipase serine motif and the N-terminal region of p43 block the action of the protein. This motif was conserved in mouse, rat and human species. The transcnit of p43 was detected in all steroidogenic tissues. Inhibition of ACTH release and steroid synthesis by dexamethasone produced a dose-dependent decrease in the abundance of the adrenal transcnpt. The transcript was induced by on vivo stimulation with ACTH. The effect had a rapid onset (5 min), reached maximal stimulation (62%) at 15 min and returned to basal levels at 30 min. ACTH effect on p43 transcript was inhibited by actinomycin D and enhanced by cycloheximide. Our results provide complete sequence of a phosphoprotein intermediary in the regulation of steroidogenesis through the activation of AA release and also the first evidence of the rapid regulation of its transcript.