PROTEIN TYROSINE PHOSPHATASES INVOLVED IN TRANSCRIPTION AND TRANSLATION OF KEY PROTEINS IN THE HORMONAL REGULATION OF STEROID SYNTHESIS

CORNEJO MACIEL F'. CASTILLA R, CASTILLO F, MALOBERTI P, DUARTE A, PODEROSO C, NEUMAN, GOROSTIZAGA A, PAZ C. PODESTÁ EJ.

Iguazú, Misiones

Congreso; XL Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2004

SAIB

It is very weIl accepted that phospho-dephosphorylation mechanisms in Ser/Thr residues play an important role in transcription and translation of key proteins in different cellular types. In this report we describe the participation of dephosphorylation processes in the control of transcription and translation in steroidogenic ceIls. Cells pre-treated wilh cycloheximide (CHX), actinomicin D (AD), phenylarsine oxide (PAO) or benzylphosphonic acid (BPA) were stimulaled with 8Br-AMPc for different times. CHX, PAO and BPA inhibit steroidogenesis (ST) at all periods of time studied. However, AD only affected ST after 1 h of stimulation. The results showing the inhibition of both phases of ST by tyrosine phosphatase inhibitors (PAO and BPA) suggest that these compounds are acting similarly lo CHX, indicating that tyrosine dephosphorylation is needed for translation. However, the analysis of two key proteins of the regulation of ST such as the acyl-CoA synthetase 4 (ACS4) and the steroidogenic acute regulatory (StAR) protein indicates that protein tyrosine phosphatases are involved in the translation of the ACS4 and in the transcription of StAR. These results show for the first time that tyrosine dephosphorylation is involved in transcription and translation in steroidogenic systems.