Identification of a 71 kDa protein as a putative non-genomic membrane progesterone receptor in boar spermatozoa

Abstract

A putative non-genomic progesterone receptor was identified by Western blot analysis from the membrane fraction but not the cytosolic fraction of boar spermatozoa using monoclonal antibody (mAb) C-262. When the membrane and the cytosolic fractions of boar liver, kidney, uterus and spermatozoa were analyzed with mAb C-262, protein bands with molecular masses of 86 and 120 kDa were detected from the cytosolic fraction of the uterus, whereas a 71 kDa protein was detected from the membrane fraction of spermatozoa. Apparently, while the 86 and 120 kDa proteins from the uterus correspond to the genomic progesterone receptor isoforms A and B in boar, the 71 kDa protein of the sperm membrane fraction seems to be a novel membrane-associated progesterone receptor. Ligand blot assay of the membrane and the cytosolic fractions of boar spermatozoa performed with peroxidaseconjugated progesterone revealed that only the 71 kDa membrane protein binds specifically to progesterone, reinforcing the results obtained from the Western blot analysis. Also ligand blot assays performed in the presence of mAb C-262 demonstrated that mAb C-262 inhibited progesterone binding to the 71 kDa protein in a dosedependent manner. Ligand blot assays performed in the presence of free progesterone, RU486 or estrogen revealed that binding of peroxidase-conjugated progesterone to the 71 kDa protein was inhibited by free progesterone and RU486 in a dose-dependent manner but not by estrogen, which further confirms that progesterone binds to the 71 kDa protein specifically. Furthermore, the progesterone-induced acrosome reaction was inhibited by mAb C-262 in a dose-dependent manner. These results strongly imply that spermatozoa possess a progesterone receptor in a membrane-bound form and can be influenced by progesterone via non-genomic progesterone receptor.

Suppression of progesterone-enhanced hyperactivation in hamster spermatozoa by estrogen

“…It also stimulates ZP penetration and the AR in hamster spermatozoa (Libersky & Boatman 1995b, Llanos & Anabalon 1996. Although spermatozoa do not have a classic intracellular progesterone receptor (PGR), a PGR is present in the cell membrane (Sabeur et al 1996, Baldi et al 1998, 2009, Lösel & Wehling 2003, Luconi et al 2004, Jang & Yi 2005. Moreover, it has been suggested that progesterone binds to the acrosome region, and PGR is localized to the same region in human (Gadkar et al 2002) and hamster spermatozoa (Noguchi et al 2008).…”

Involvement of signaling pathways in bovine sperm motility, and effect of ergot alkaloids

“…Membrane receptors are involved with the regulation of mammalian sperm function (Shen et al 1993;Roldan et al 1994;Allegrucci et al 2001;Adeoya-Osiguwa and Fraser 2005;Jang and Yi 2005). Some membrane receptors are functionally coupled to G-proteins which can alter intracellular cAMP and calcium concentrations (Eason et al 1992;Pihlavisto and Scheinin 1999;Pohjanoksa et al 1997;Allegrucci et al 2001).…”

The cyclic AMP-dependent protein kinase A pathway is involved in progesterone effects on calcitonin secretion from TT cells

“…Ni and co-workers reported that progesterone regulates CRH gene transcription via a cAMP regulatory element in the CRH promoter (Ni et al, 2004). Recently, the human membrane progesterone receptor (Jang and Yi, 2005) and receptor gene were identified (Bernauer et al, 2001). Hanna and co-workers also suggested that zebrafish membrane progestin receptor (mPR) alpha and mPR beta signal similarly upon progestin binding, resulting in rapid activation of MAPK and downregulation of adenylyl cyclase activity (Hanna et al, 2006).…”