Impact of the Post-Translational Regulation of MAPK Phosphatase-1 (MKP-1) on cAMP-Induced NUR77 Expression

M. MORI SEQUEIROS GARCÍA; A. GOROSTIZAGA; L. BRION; S. NUDLER; S. GONZALEZ-CALVAR; C. PAZ

Chicago, Illinois

Conferencia; Adrenal 2014; 2014

Endocrine Society

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) demonstrate for the first time that the cAMP-mediated increases 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-lives of flag-MKP-1-S296A-S323A and flag MKP-1-S359A-S364A are increased (140 min) and decreases (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 and flag-MKP-1-S296A-S323A reduce cAMP-induced 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.