title: MAPK phosphatase-1 (MKP-1) expression is up-regulated by hCG/cAMP and modulates steroidogenesis in MA-10 Leydig cells.
abstract: MAP kinases (MAPKs), such as ERK1/2, exert profound effects on a variety of physiological processes. In steroidogenic cells, ERK1/2 are involved in the expression and activation of steroidogenic acute regulatory protein, which plays a central role in the regulation of steroidogenesis. In MA-10 Leydig cells, LH and chorionic gonadotropin (CG) trigger transient ERK1/2 activation via protein kinase A, although the events that lead to ERK1/2 inactivation are not fully described. Here, we describe the hormonal regulation of MAPK phosphatase-1 (MKP-1), an enzyme that inactivates MAPKs, in MA-10 cells. In our experiments, human CG (hCG)/cAMP stimulation rapidly and transiently increased MKP-1 mRNA levels by a transcriptional action. This effect was accompanied by an increase in protein levels in both nuclear and mitochondrial compartments. In cells transiently expressing flag-MKP-1 protein, hCG/cAMP promoted the accumulation of the recombinant protein in a time-dependent manner (10-fold at 1 h). Moreover, hCG/cAMP triggered ERK1/2-dependent MKP-1 phosphorylation. The blockade of cAMP-induced MAPK kinase/ERK activation abated MKP-1 phosphorylation but only partially reduced flag-MKP-1 protein accumulation. Together, these results suggest that hCG regulates MKP-1 at transcriptional and posttranslational level, protein phosphorylation being one of the mechanisms involved in this regulation. Our study also demonstrates that MKP-1 overexpression reduces the effects of cAMP on ERK1/2 phosphorylation, steroidogenic acute regulatory gene promoter activity, mRNA levels, and steroidogenesis, whereas MKP-1 down-regulation by small interfering RNA produces opposite effects. In summary, our data demonstrate that hCG regulates MKP-1 expression at multiple stages as a negative feedback regulatory mechanism to modulate the hormonal action on ERK1/2 activity and steroidogenesis.
authors.affiliation: Institute of Molecular Research in Hormonal, Neurodegenerative and Oncological Diseases, Department of Biochemistry, School of Medicine, University of Buenos Aires, Paraguay 2155, 5th Floor, C1121ABG Buenos Aires, Argentina.
authors.forename: Laura
authors.initials: L
authors.lastname: Brion
authors.forename: Paula M
authors.initials: PM
authors.lastname: Maloberti
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Gomez
authors.forename: Cecilia
authors.initials: C
authors.lastname: Poderoso
authors.forename: Alejandra B
authors.initials: AB
authors.lastname: Gorostizaga
authors.forename: Maria M
authors.initials: MM
authors.lastname: Mori Sequeiros Garcia
authors.forename: Andrea B
authors.initials: AB
authors.lastname: Acquier
authors.forename: Mariana
authors.initials: M
authors.lastname: Cooke
authors.forename: Carlos F
authors.initials: CF
authors.lastname: Mendez
authors.forename: Ernesto J
authors.initials: EJ
authors.lastname: Podesta
authors.forename: Cristina
authors.initials: C
authors.lastname: Paz
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism*; D054638:Dual Specificity Phosphatase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D006063:Chorionic Gonadotropin; D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D000098682:Steroidogenic Acute Regulatory Protein; D000242:Cyclic AMP; D054638:Dual Specificity Phosphatase 1; C517020:Dusp1 protein, mouse