IMPACT OF THE POST-TRANSLATIONAL REGULATION OF MAPK PHOSPHATASE-1 (MKP-1) ON cAMP-INDUCED NUR77 EXPRESSION

MORI SEQUEIROS GARCÍA M; GOROSTIZAGA, AB; BRION L; NUDLER S; GONZALES-CALVAR S,; PAZ C

Chicago

Congreso; Adrenal Cortex Conference; 2014

Bernard Shimmer and Alexander Brownie, members of the Organizing Commitee

IMPACT OF THE POST-TRANSLATIONAL REGULATION OF MAPK PHOSPHATASE-1 (MKP-1) ON cAMP-INDUCED NUR77 EXPRESSION M. Mori Sequeiros Garcia, A. Gorostizaga, S. Nudler, L. Brion, S. Gonzalez-Calvar, F. Méndez, C. Paz. INBIOMED, Dept of Biochemistry, School of Medicine, University of Buenos Aires, Argentina In MA-10 Leydig cells, LH receptor activation up-regulates MKP-1 by transcriptional and post-translational mechanisms. In this cell line we analyze 1) whether the cAMP-mediated expression of NUR77, a factor involved in the expression of steroidogenic genes like STARD1, is an ERK-dependent process and 2) the impact of MKP-1 and its phosphorylation in ERK consensus sites on such expression. We demonstrate, for the first time, that the cAMP-mediated increase in NUR77 promoter activity and mRNA levels are ERK-dependent processes. The evaluation of the half-life of flag-MKP-1 chimeras lacking ERK-phosphorylation sites demonstrates that the half-life of flag-MKP-1-S296A-S323A and flag-MKP-1-S359A-S364A, are increased (>150 min) and decreased (45 min), respectively, after cAMP stimulation, as compared with flag-MKP-1 wild type (120 min).These results suggest that S359 and S364 phosphorylation stabilizes MKP-1. Accordingly, flag-MKP-1 expression reduces the effect of cAMP on NUR77 expression, while flag-MKP-1-S359A-S364A has no effect. Thus, multi-site ERK-mediated phosphorylation regulates MKP-1 half-life, which in turn modulates ERK-dependent processes, like NUR77 expression.