Prohibitin regulates the FSH signaling pathway in rat granulosa cell differentiation

    1. Winston E Thompson2,5
    1. 1Department of Obstetrics and Gynecology, Morehouse School of Medicine, Atlanta, Georgia, USA
    2. 2Reproductive Science Research Program, Morehouse School of Medicine, Atlanta, Georgia, USA
    3. 3Department of Neurobiology, Morehouse School of Medicine, Atlanta, Georgia, USA
    4. 4Department of Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
    5. 5Department of Physiology, Morehouse School of Medicine, Atlanta, Georgia, USA
    1. Correspondence should be addressed to W E Thompson; Email: wthompson{at}


    Published results from our laboratory identified prohibitin (PHB), a gene product expressed in granulosa cells (GCs) that progressively increases during follicle maturation. Our current in vitro studies demonstrate that follicle-stimulating hormone (FSH) stimulates Phb expression in rat primary GCs. The FSH-dependent expression of PHB was primarily localized within mitochondria, and positively correlates with the morphological changes in GCs organelles, and synthesis and secretions of estradiol (E2) and progesterone (P4). In order to confirm that PHB plays a regulatory role in rat GC differentiation, endogenous PHB-knockdown studies were carried out in undifferentiated GCs using adenoviral (Ad)-mediated RNA interference methodology. Knockdown of PHB in GCs resulted in the suppression of the key steroidogenic enzymes including steroidogenic acute regulatory protein (StAR), p450 cholesterol side-chain cleavage enzyme (p450scc), 3β-hydroxysteroid dehydrogenase (3β-HSD), and aromatase (Cyp19a1); and decreased E2 and P4 synthesis and secretions in the presence of FSH stimulation. Furthermore, these experimental studies also provided direct evidence that PHB within the mitochondrial fraction in GCs is phosphorylated at residues Y249, T258, and Y259 in response to FSH stimulation. The observed levels of phosphorylation of PHB at Y249, T258, and Y259 were significantly low in GCs in the absence of FSH stimulation. In addition, during GC differentiation FSH-induced expression of phospho-PHB (pPHB) requires the activation of MEK1-ERK1/2 signaling pathway. Taken together, these studies provide new evidence supporting FSH-dependent PHB/pPHB upregulation in GCs is required to sustain the differentiated state of GCs.

    • Received 3 March 2016
    • Accepted 31 March 2016
    • Made available online as an Accepted Preprint 1 May 2016

    Graphic This work is licensed under a Creative Commons Attribution 3.0 Unported License.

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