title: Extracellular Signal-regulated Kinase (ERK)-dependent Phosphorylation of Y-Box-binding Protein 1 (YB-1) Enhances Gene Expression in Granulosa Cells in Response to Follicle-stimulating Hormone (FSH).
abstract: Within the ovarian follicle, immature oocytes are surrounded and supported by granulosa cells (GCs). Stimulation of GCs by FSH leads to their proliferation and differentiation, events that are necessary for fertility. FSH activates multiple signaling pathways to regulate genes necessary for follicular maturation. Herein, we investigated the role of Y-box-binding protein-1 (YB-1) within GCs. YB-1 is a nucleic acid binding protein that regulates transcription and translation. Our results show that FSH promotes an increase in the phosphorylation of YB-1 on Ser(102) within 15 min that is maintained at significantly increased levels until ∼8 h post treatment. FSH-stimulated phosphorylation of YB-1(Ser(102)) is prevented by pretreatment of GCs with the PKA-selective inhibitor PKA inhibitor (PKI), the MEK inhibitor PD98059, or the ribosomal S6 kinase-2 (RSK-2) inhibitor BI-D1870. Thus, phosphorylation of YB-1 on Ser(102) is PKA-, ERK-, and RSK-2-dependent. However, pretreatment of GCs with the protein phosphatase 1 (PP1) inhibitor tautomycin increased phosphorylation of YB-1(Ser(102)) in the absence of FSH; FSH did not further increase YB-1(Ser(102)) phosphorylation. This result suggests that the major effect of RSK-2 is to inhibit PP1 rather than to directly phosphorylate YB-1 on Ser(102) YB-1 coimmunoprecipitated with PP1β catalytic subunit and RSK-2. Transduction of GCs with the dephospho-adenoviral-YB-1(S102A) mutant prevented the induction by FSH of Egfr, Cyp19a1, Inha, Lhcgr, Cyp11a1, Hsd17b1, and Pappa mRNAs and estradiol-17β production. Collectively, our results reveal that phosphorylation of YB-1 on Ser(102) via the ERK/RSK-2 signaling pathway is necessary for FSH-mediated expression of target genes required for maturation of follicles to a preovulatory phenotype.
authors.affiliation: From the School of Molecular Biosciences, Washington State University, Pullman, Washington 99164.
authors.forename: Elyse M
authors.initials: EM
authors.lastname: Donaubauer
authors.affiliation: From the School of Molecular Biosciences, Washington State University, Pullman, Washington 99164 mehd@vetmed.wsu.edu.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Hunzicker-Dunn
mesh_terms: D000818:Animals; D001141:Aromatase / Q000235:genetics; D015153:Blotting, Western; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D066246:ErbB Receptors / Q000235:genetics; D004958:Estradiol / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000037:antagonists & inhibitors / Q000378:metabolism; D012694:Serine / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013997:Time Factors; D051840:Y-Box-Binding Protein 1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D047428:Protein Kinase Inhibitors; D051840:Y-Box-Binding Protein 1; D012694:Serine; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D001141:Aromatase; D066246:ErbB Receptors; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C069330:ribosomal protein S6 kinase, 90kDa, polypeptide 3; D017868:Cyclic AMP-Dependent Protein Kinases; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: Y-box-binding protein 1 (YB-1); extracellular-signal-regulated kinase (ERK); follicle-stimulating hormone (FSH); gene expression; granulosa cells (GCs); ovary; protein kinase A (PKA)