title: Lhcgr expression in granulosa cells: roles for PKA-phosphorylated β-catenin, TCF3, and FOXO1.
abstract: Ovarian follicles lacking FSH or FSH receptors fail to progress to a preovulatory stage, resulting in infertility. One hallmark of the preovulatory follicle is the presence of luteinizing hormone/choriogonadotropin receptors (LHCGR) on granulosa cells (GCs). However, the mechanisms by which FSH induces Lhcgr gene expression are poorly understood. Our results show that protein kinase A (PKA) and phosphoinositide 3-kinase (PI3K)/AKT pathways are required for FSH to activate both the murine Lhcgr-luciferase reporter and expression of Lhcgr mRNA in rat GCs. Based on results showing that an adenovirus (Ad) expressing a steroidogenic factor 1 (SF1) mutant that cannot bind β-catenin abolished FSH-induced Lhcgr mRNA, we evaluated the role of β-catenin in the regulation of Lhcgr gene expression. FSH promoted the PKA-dependent, PI3K-independent phosphorylation of β-catenin on Ser552 and Ser665. FSH activated the β-catenin/T-cell factor (TCF) artificial promoter-reporter TOPFlash via a PKA-dependent, PI3K-independent pathway, and dominant-negative (DN) TCF abolished FSH-activated Lhcgr-luciferase reporter and induction of Lhcgr mRNA. Microarray analysis of GCs treated with Ad-DN-TCF and FSH identified the Lhcgr as the most down-regulated gene. Chromatin immunoprecipitation results placed β-catenin phosphorylated on Ser552 and Ser675 and SF1 on the Lhcgr promoter in FSH-treated GCs; TCF3 was constitutively associated with the Lhcgr promoter. Transduction with an Ad-phospho-β-catenin mutant (Ser552/665/Asp) enhanced Lhcgr mRNA expression in FSH-treated cells greater than 3-fold. Finally, we identified a recognized PI3K/AKT target, forkhead box O1, as a negative regulator of Lhcgr mRNA expression. These results provide new understanding of the complex regulation of Lhcgr gene expression in GCs.
authors.affiliation: School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-7520, USA.
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Law
authors.forename: Jennifer
authors.initials: J
authors.lastname: Weck
authors.forename: Brandon
authors.initials: B
authors.lastname: Kyriss
authors.forename: John H
authors.initials: JH
authors.lastname: Nilson
authors.forename: Mary
authors.initials: M
authors.lastname: Hunzicker-Dunn
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D015536:Down-Regulation; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005786:Gene Expression Regulation; D006107:Granulosa Cells / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D006080:Ovarian Follicle / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011967:Receptors, Gonadotropin / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D011974:Receptors, LH / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D054339:Steroidogenic Factor 1 / Q000235:genetics / Q000378:metabolism; D058125:Transcription Factor 7-Like 1 Protein / Q000378:metabolism; D014162:Transfection; D051176:beta Catenin / Q000378:metabolism; D000071161:Forkhead Box Protein O1
chemical_list: D017868:Cyclic AMP-Dependent Protein Kinases; D005640:Follicle Stimulating Hormone; D051858:Forkhead Transcription Factors; D009419:Nerve Tissue Proteins; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D011967:Receptors, Gonadotropin; D011974:Receptors, LH; D054339:Steroidogenic Factor 1; D058125:Transcription Factor 7-Like 1 Protein; D051176:beta Catenin; C074639:Foxo1 protein, rat; D000071161:Forkhead Box Protein O1