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?-catenin regulates GnRH-induced FSH? gene expression.

ABSTRACT: The regulation of gonadotropin synthesis by GnRH plays an essential role in the neuroendocrine control of reproduction. The known signaling mechanisms involved in gonadotropin synthesis have been expanding. For example, involvement of ?-catenin in LH? induction by GnRH has been discovered. We examined the role of ?-catenin in FSH? gene expression in L?T2 gonadotrope cells. GnRH caused a sustained increase in nuclear ?-catenin levels, which was significantly reduced by c-Jun N-terminal kinase (JNK) inhibition. Small interfering RNA-mediated knockdown of ?-catenin mRNA demonstrated that induction of FSH? mRNA by GnRH depended on ?-catenin and that regulation of FSH? by ?-catenin occurred independently of the JNK-c-jun pathway. ?-Catenin depletion had no impact on FSH? mRNA stability. In L?T2 cells transfected with FSH? promoter luciferase fusion constructs, GnRH responsiveness was conferred by the proximal promoter (-944/-1) and was markedly decreased by ?-catenin knockdown. However, none of the T-cell factor/lymphoid enhancer factor binding sites in that region were required for promoter activation by GnRH. Chromatin immunoprecipitation further corroborated the absence of direct interaction between ?-catenin and the 1.8-kb FSH? promoter. To elucidate the mechanism for the ?-catenin effect, we analyzed approximately 1 billion reads of next-generation RNA sequencing ?-catenin knockdown assays and selected the nuclear cofactor breast cancer metastasis-suppressor 1-like (Brms1L) as one candidate for further study. Subsequent experiments confirmed that Brms1L mRNA expression was decreased by ?-catenin knockdown as well as by JNK inhibition. Furthermore, knockdown of Brms1L significantly attenuated GnRH-induced FSH? expression. Thus, our findings indicate that the expression of Brms1L depends on ?-catenin activity and contributes to FSH? induction by GnRH.

SUBMITTER: Wang Q

PROVIDER: S-EPMC3683805 | biostudies-literature | 2013 Feb

REPOSITORIES: biostudies-literature

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β-catenin regulates GnRH-induced FSHβ gene expression.

Wang Qian Q Chikina Maria M Zaslavsky Elena E Pincas Hanna H Sealfon Stuart C SC

Molecular endocrinology (Baltimore, Md.) 20121204 2

The regulation of gonadotropin synthesis by GnRH plays an essential role in the neuroendocrine control of reproduction. The known signaling mechanisms involved in gonadotropin synthesis have been expanding. For example, involvement of β-catenin in LHβ induction by GnRH has been discovered. We examined the role of β-catenin in FSHβ gene expression in LβT2 gonadotrope cells. GnRH caused a sustained increase in nuclear β-catenin levels, which was significantly reduced by c-Jun N-terminal kinase (JN ...[more]

PMID: 23211523

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Project description:Study hypothesisWe hypothesized that Runt-related transcription factor 2 (RUNX2), matrix metalloproteinase (MMP)2 and MMP9 are involved in basal and gonadotrophin-releasing hormone (GnRH)-induced human extravillous trophoblast (EVT) cell invasion.Study findingOur finding indicates that GnRH-induced RUNX2 expression enhances the invasive capacity of EVT cells by modulating the expression of MMP2 and MMP9.What is known alreadyGnRH is expressed in first-trimester placenta and exerts pro-invasive effects on EVT cells in vitro. RUNX2 regulates MMP2 and MMP9 expression and is often associated with invasive phenotypes.Study design, samples/materials, methodsFirst-trimester human placenta (n = 9) was obtained from women undergoing elective termination of pregnancy. The localization of RUNX2, MMP2 and MMP9 in first-trimester human placenta was examined by immunohistochemistry. Primary or immortalized (HTR-8/SVneo) EVT cells were treated alone or in combination with GnRH, GnRH antagonist Antide, MAPK kinase inhibitor PD98095, phosphatidylinositol 3-kinase inhibitor LY294002, MMP2/9 inhibitor or small interfering RNAs (siRNAs) targeting RUNX2, MMP2 and/or MMP9. Protein and mRNA levels were measured by western blot and RT-PCR, respectively. Cell invasiveness was evaluated by transwell Matrigel or collagen I invasion assays.Main results and the role of chanceRUNX2, MMP2 and MMP9 were detected in the cell column regions of human first-trimester placental villi. GnRH treatment increased RUNX2 mRNA and protein levels in HTR-8/SVneo cells and primary EVTs, and these effects were attenuated by co-treatment with Antide, PD98095 or LY294002. Down-regulation of RUNX2 by siRNA reduced basal and GnRH-induced MMP2/9 expression and cell invasion. Moreover, pharmacological inhibition or siRNA-mediated knockdown of MMP2/9 reduced basal and GnRH-induced cell invasion.Limitations, reasons for cautionThe lack of an in vivo model is the major limitation of our in vitro study.Wider implications of the findingsOur findings provide important insight into the functions of the GnRH - GnRH receptor system in early implantation and placentation.Large scale dataNot applicable.Study funding and competing interestsThis research was supported by Canadian Institutes of Health Research (Grant #143317) to P.C.K.L. The authors have nothing to disclose.

Dataset Information

?-catenin regulates GnRH-induced FSH? gene expression.

Publications

β-catenin regulates GnRH-induced FSHβ gene expression.

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