Spatio-temporal regulation of ERK activity by hCG in Leydig cells: participation of different MAP kinase phosphatases (MKPs).

MORI SEQUEIROS GARCIA, M; GOMEZ, NV; BRION, LAURA; GOROSTIZAGA, AB; ACQUIER, A; DUARTE, A; MENDEZ, CF; PODESTÁ, ERNESTO

League City

Congreso; Adrenal 2012 - Conference on the adrenal cortex; 2012

Several MKPs regulate ERK activity. We have demonstrated that nuclear MKP-1 is rapidly induced by hCG and cAMP through transcriptional and posttranslational mechanisms in MA-10 Leydig cells. MKP-1 down-regulation by small interfering RNA increases the hormonal effects on ERK1/2 activity, StAR gene expression and steroidogenesis. MKP-3 is a cytosolic enzyme induced by proliferative signals. Here we show that hCG also regulates MKP-3, as this hormone and 8Br-cAMP transiently increased MKP-3 mRNA levels (2-fold at 3 h stimulation). These two stimuli also increased flag-MKP-3 levels as assessed by Western blot using an anti-Flag antibody. Since the chimaera is under the control of a constitutive promoter, this result suggests that a hormone-induced post translational modification increases MKP-3 half-life. Moreover, 8Br-cAMP stimulation resulted in flag-MKP-3 accumulation in the cytosol and reduced ERK1/2 phosphorylation. Thus, induction of MKP-3 and MKP-1 by LH/hCG could exert a strict spatio-temporal control on MAP kinases to regulate different events such as proliferation and steroidogenesis.