title: MAPK phosphatase-2 (MKP-2) is induced by hCG and plays a role in the regulation of CYP11A1 expression in MA-10 Leydig cells.
abstract: MAPKs such as ERK1/2 are dephosphorylated, and consequently inactivated, by dual specificity phosphatases (MKPs). In Leydig cells, LH triggers ERK1/2 phosphorylation through the action of protein kinase A. We demonstrate that, in MA-10 Leydig cells, LH receptor activation by human chorionic gonadotropin (hCG) up-regulates MKP-2, a phosphatase that dephosphorylates ERK1/2, among other MAPKs. After 2 hours, hCG and 8-bromo-cAMP (8Br-cAMP) significantly increased MKP-2 mRNA levels (3-fold), which declined to basal levels after 6 hours. MKP-2 protein accumulation exhibited a similar kinetic profile. In cells transiently expressing flag-MKP-2 protein, hCG/8Br-cAMP stimulation promoted the accumulation of the chimera (2.5-fold after 3 h of stimulation). Pharmacologic and biochemical approaches showed that the accumulation of flag-MKP-2 involves a posttranslational modification that increases MKP-2 half-life. MKP-2 down-regulation by a short hairpin RNA (MKP-2 shRNA) raised the levels of phosphorylated ERK1/2 reached by 8Br-cAMP stimulation. This effect was evident after 180 min of stimulation, which suggests that MKP-2 down-regulates the late phase of cAMP-induced ERK1/2 activity. Also, MKP-2 down-regulation by MKP-2 shRNA increased the stimulatory effect of 8Br-cAMP on both promoter activity and messenger levels of CYP11A1, which encodes for the steroidogenic enzyme P450scc and is induced by LH/hCG through protein kinase A and ERK1/2 activities. Our findings demonstrate, for the first time, that LH/hCG tightly regulates MKP-2 expression, which modulates the induction of CYP11A1 by 8Br-cAMP. MKP-2 up-regulation might control ERK1/2 activity in a specific temporal frame to modulate the expression of a finite repertory of ERK-dependent genes.
authors.affiliation: Laboratory of Phosphatases in Signal Transduction, Institute for Biomedical Research (INBIOMED), Department of Biochemistry, School of Medicine, University of Buenos Aires, Paraguay 2155, (C1121ABG) Buenos Aires, Argentina.
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Gómez
authors.forename: Alejandra B
authors.initials: AB
authors.lastname: Gorostizaga
authors.forename: María M
authors.initials: MM
authors.lastname: Mori Sequeiros García
authors.forename: Laura
authors.initials: L
authors.lastname: Brion
authors.forename: Andrea
authors.initials: A
authors.lastname: Acquier
authors.forename: Silvia I
authors.initials: SI
authors.lastname: González-Calvar
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Méndez
authors.forename: Ernesto J
authors.initials: EJ
authors.lastname: Podestá
authors.forename: Cristina
authors.initials: C
authors.lastname: Paz
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D007985:Leydig Cells / Q000201:enzymology*; D008297:Male; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D011974:Receptors, LH / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D006063:Chorionic Gonadotropin; D012333:RNA, Messenger; D011974:Receptors, LH; D015124:8-Bromo Cyclic Adenosine Monophosphate; D002786:Cholesterol Side-Chain Cleavage Enzyme; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C522186:Dusp4 protein, mouse; D017027:Protein Tyrosine Phosphatases