Progesterone suppresses an oxytocin-stimulated signal pathway in COS-7 cells transfected with the oxytocin receptor

Cecily Bishop, Theresa Filtz, Yong Zhang, Ov Slayden, Fredrick Stormshak

    Research output: Contribution to journalArticle

    3 Citations (Scopus)

    Abstract

    The present study was conducted to determine if progesterone (P4) would inhibit oxytocin-stimulated phosphoinositide hydrolysis in COS-7 cells expressing transfected ovine oxytocin receptor (OTR) with little or no nuclear P4 receptor (nPR) protein present. The relative absence of nPR in these cells was confirmed by immunocytochemistry and RT-PCR. To investigate the effects of P4 on oxytocin (OT) signaling, cells were transiently transfected with the ovine OTR. Radioreceptor assay for [3H]-OT binding confirmed the presence of a high affinity binding site for OT in transfected cells, while treatment with P4 and GTPγS (which uncouples the OTR from the heterotrimeric G-protein) increased the Kd for OT binding slightly. Cells were then assayed for inositol phosphate hydrolysis 48 h post-transfection. Pre-treatment of cells with P4 for 10 min significantly interfered with rapid (20 min) OT-stimulated inositol trisphosphate (IP3) production. This inhibition was specific to P4, because pre-treatment of cells with promegestone (R5020), testosterone, mifepristone (RU 486), or cortisol did not decrease OT-stimulated IP3 levels. By radioreceptor assay for PR, no measurable specific binding of R5020 was observed for either transfected or non-transfected cells. We conclude that P4 can inhibit OTR-mediated phosphoinositide hydrolysis in COS-7 cells that express little or no nPR protein. These data support a role for a non-genomic action for P4 in OTR signaling via some mechanism other than by binding to a membrane progestin receptor in an immortalized, transfected cell.

    Original languageEnglish (US)
    Pages (from-to)1367-1374
    Number of pages8
    JournalSteroids
    Volume73
    Issue number14
    DOIs
    StatePublished - Dec 22 2008

    Fingerprint

    Oxytocin Receptors
    COS Cells
    Oxytocin
    Progesterone
    Signal Transduction
    Promegestone
    Cytoplasmic and Nuclear Receptors
    Hydrolysis
    Mifepristone
    Cells
    Radioligand Assay
    Phosphatidylinositols
    Assays
    Sheep
    Cell signaling
    Heterotrimeric GTP-Binding Proteins
    Inositol Phosphates
    Inositol
    Progesterone Receptors
    Hydrocortisone

    Keywords

    • Non-genomic
    • Oxytocin
    • Oxytocin receptor
    • Phosphoinositides
    • Progesterone

    ASJC Scopus subject areas

    • Biochemistry
    • Clinical Biochemistry
    • Endocrinology
    • Molecular Biology
    • Organic Chemistry
    • Pharmacology

    Cite this

    Progesterone suppresses an oxytocin-stimulated signal pathway in COS-7 cells transfected with the oxytocin receptor. / Bishop, Cecily; Filtz, Theresa; Zhang, Yong; Slayden, Ov; Stormshak, Fredrick.

    In: Steroids, Vol. 73, No. 14, 22.12.2008, p. 1367-1374.

    Research output: Contribution to journalArticle

    Bishop, Cecily ; Filtz, Theresa ; Zhang, Yong ; Slayden, Ov ; Stormshak, Fredrick. / Progesterone suppresses an oxytocin-stimulated signal pathway in COS-7 cells transfected with the oxytocin receptor. In: Steroids. 2008 ; Vol. 73, No. 14. pp. 1367-1374.
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