Involvement of an Unnamed Protein, RDA288, in the Mechanism through which Progesterone Mediates Its Antiapoptotic Action in Spontaneously Immortalized Granulosa Cells

Abstract

Progesterone (P4) inhibits apoptosis of rat granulosa cells and spontaneously immortalized granulosa cells (SIGCs), which were derived from rat granulosa cells. Defining the mechanism through which P4 mediates its action has been difficult because these cells do not express the classic nuclear P4 receptor. Previous studies have shown that a P4 receptor antibody, C-262, detects a 60-kDa protein that is involved in regulating P4's antiapoptotic action. Using a C-262 affinity column, this 60-kDa protein was isolated and sequenced by mass spectrometry. This analysis revealed that the C-262-detectable protein is an unnamed protein referred to as RDA288. This protein has several putative hyaluronic acid binding sites. Further hyaluronic acid antagonizes (3)H-P4 binding to SIGCs and mimics P4's action, whereas exogenous hyaluronic acid binding protein attenuates P4's actions. RT-PCR demonstrated that RDA288 mRNA was present in SIGCs, immature rat ovary, lung, and skeletal muscle but was not present in several other organs. Forced expression of RDA288 increased the capacity of SIGCs to bind and respond to P4. An antibody was also developed against RDA288. Using this antibody in a Western blot protocol, RDA288 expression was confirmed in both SIGCs and granulosa cells. An immunohistochemical study detected RDA288 in the cytoplasm and plasma membrane components of granulosa cells of antral follicles. Immunocytochemical studies on living nonpermeabilized SIGCs revealed that RDA288 was present on the extracellular surface of the plasma membrane. Finally, pretreatment with the RDA288 antibody blocked P4's antiapoptotic actions. Taken together, these data suggest that RDA288 plays a significant role in mediating P4's antiapoptotic action in granulosa cells.

Progesterone receptor membrane component 1 promotes survival of human breast cancer cells and the growth of xenograft tumors

“…55,56 P4 also blocks apoptosis in lactating mammary glands 57 and supplementation of P4 following weaning can prevent regression of mammary tissue by attenuating epithelial cell death. 56 A number of studies involving both primary cells 58 and transformed cell lines 13 have demonstrated that P4 prevents cells from undergoing apoptosis during stress regardless of whether or not the cells express the classical PGR. Our findings here place PGRMC1 squarely in the middle of the pathway by which progestins promote survival of cancer cells derived from female reproductive tissues.…”

Expression of membrane progesterone receptors on human T lymphocytes and Jurkat cells and activation of G-proteins by progesterone

“…Some examples of such nongenomic progesterone action include facilitation of female mouse sexual behavior (Frye & Vongher 1999), oocyte maturation in Xenopus (Masui & Markert 1971), and spotted sea trout (Zhu et al 2003b), as well as the acrosome reaction in sperm (Meizel & Turner 1991). Putative mPRs have been identified in tissues such as human sperm (Luconi et al 1998, rat brain (Krebs et al 2000), rat granulosa cells (Peluso et al 2004), porcine liver (Meyer et al 1996), human liver, kidney, and placenta (Meyer et al 1998). Members of the mPR family described in this study have previously been identified in fish oocytes (Zhu et al 2003b), fish sperm (Thomas et al 2005b), various human tissues (Zhu et al 2003a, Chapman et al 2006, Karteris et al 2006, Dressing & Thomas 2007, Nutu et al 2007, rat corpus luteum (Cai & Stocco 2005), and sheep ovary (Ashley et al 2006).…”

Xenopus cDNA microarray identification of genes with endodermal organ expression

“…5; Table 2E). Rda288, also known as PAIRBP1 (Plasminogen activator inhibitor 1 RNA-binding protein or PAI-1 mRNA binding protein), is involved in mediating the antiapoptotic action of progesterone (P4) in spontaneously immortalized granulose cells (SIGCs) (Peluso et al, 2004). Its expression is also regulated by gonadotropins in granulose and luteal cells (Peluso et al, 2005).…”