title: FSH stimulates IRS-2 expression in human granulosa cells through cAMP/SP1, an inoperative FSH action in PCOS patients.
abstract: Follicle stimulating hormone (FSH) plays a central role in growth and differentiation of ovarian follicles. A plethora of information exists on molecular aspects of FSH responses but little is known about the mechanisms involved in its cross-talk with insulin/IGF-1 pathways implicated in the coordination of energy homeostasis in preovulatory granulosa cells (GCs). In this study, we hypothesized that FSH may regulate IRS-2 expression and thereby maintain the energy balance in GCs. We demonstrate here that FSH specifically increases IRS-2 expression in human and rat GCs. FSH-stimulated IRS-2 expression was inhibited by actinomycin D or cycloheximide. Furthermore, FSH decreases IRS-2 mRNA degradation indicating post-transcriptional stabilization. Herein, we demonstrate a role of cAMP pathway in the activation of IRS-2 expression by FSH. Scan and activity analysis of IRS-2 promoter demonstrated that FSH regulates IRS-2 expression through SP1 binding sites. FSH stimulates SP1 translocation into nucleus and its binding to IRS-2 promoter. These results are corroborated by the fact that siRNA mediated knockdown of IRS-2 decreased the FSH-stimulated PI3K activity, p-Akt levels, GLUT4 translocation and glucose uptake. However, FSH was not able to increase IRS-2 expression in GCs from PCOS women undergoing IVF. Interestingly, IRS-2 mRNA expression was downregulated in GCs from the PCOS rat model. Taken together, our findings establish that FSH induces IRS-2 expression and thereby activates PI3K, Akt and glucose uptake. Crucially, our data confirms a molecular defect in FSH action in PCOS GCs which may cause deceleration of metabolism and follicular growth leading to infertility. These results lend support for a therapeutic potential of IRS-2 in the management of PCOS.
authors.affiliation: Division of Molecular Endocrinology and Reproduction, Department of Zoology, University of Delhi, Delhi 110007, India.
authors.forename: G
authors.initials: G
authors.lastname: Anjali
authors.affiliation: Division of Molecular Endocrinology and Reproduction, Department of Zoology, University of Delhi, Delhi 110007, India.
authors.forename: Surleen
authors.initials: S
authors.lastname: Kaur
authors.affiliation: Division of Molecular Endocrinology and Reproduction, Department of Zoology, University of Delhi, Delhi 110007, India.
authors.forename: Ruchi
authors.initials: R
authors.lastname: Lakra
authors.affiliation: Division of Molecular Endocrinology and Reproduction, Department of Zoology, University of Delhi, Delhi 110007, India.
authors.forename: Jyoti
authors.initials: J
authors.lastname: Taneja
authors.affiliation: Division of Molecular Endocrinology and Reproduction, Department of Zoology, University of Delhi, Delhi 110007, India.
authors.forename: Gaganjot S
authors.initials: GS
authors.lastname: Kalsey
authors.affiliation: Division of Molecular Endocrinology and Reproduction, Department of Zoology, University of Delhi, Delhi 110007, India.
authors.forename: Anjali
authors.initials: A
authors.lastname: Nagendra
authors.affiliation: National Institute of Health and Family Welfare, New Delhi 110067, India.
authors.forename: T G
authors.initials: TG
authors.lastname: Shrivastav
authors.affiliation: Gouri Hospitals, Delhi 110007, India.
authors.forename: M Gouri
authors.initials: MG
authors.lastname: Devi
authors.affiliation: Department of Obstetrics and Gynecology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Neena
authors.initials: N
authors.lastname: Malhotra
authors.affiliation: Department of Obstetrics and Gynecology, All India Institute of Medical Sciences, New Delhi 110029, India.
authors.forename: Alka
authors.initials: A
authors.lastname: Kriplani
authors.affiliation: Division of Molecular Endocrinology and Reproduction, Department of Zoology, University of Delhi, Delhi 110007, India. Electronic address: ghrika_s@yahoo.com.
authors.forename: Rita
authors.initials: R
authors.lastname: Singh
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D006107:Granulosa Cells / Q000378:metabolism*; D006801:Humans; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics / Q000378:metabolism*; D011085:Polycystic Ovary Syndrome / Q000378:metabolism* / Q000473:pathology; D011401:Promoter Regions, Genetic; D020871:RNA Stability; D017207:Rats, Sprague-Dawley; D015290:Second Messenger Systems; D016329:Sp1 Transcription Factor / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D051275:Glucose Transporter Type 4; C526297:IRS2 protein, human; D055504:Insulin Receptor Substrate Proteins; C495694:Slc2a4 protein, rat; D016329:Sp1 Transcription Factor; C108209:SP1 protein, human; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP; D005947:Glucose
keywords: FSH; Granulosa cells; IRS-2; PCOS; cAMP