title: Sperm-specific post-acrosomal WW-domain binding protein (PAWP) does not cause Ca2+ release in mouse oocytes.
abstract: Mature mammalian oocytes undergo a prolonged series of cytoplasmic calcium (Ca(2+)) oscillations at fertilization that are the cause of oocyte activation. The Ca(2+) oscillations in mammalian oocytes are driven via inositol 1,4,5-trisphosphate (IP3) generation. Microinjection of the sperm-derived phospholipase C-zeta (PLCζ), which generates IP3, causes the same pattern of Ca(2+) oscillations as observed at mammalian fertilization and it is thought to be the physiological agent that triggers oocyte activation. However, another sperm-specific protein, 'post-acrosomal WW-domain binding protein' (PAWP), has also been reported to elicit activation when injected into mammalian oocytes, and to produce a Ca(2+) increase in frog oocytes. Here we have investigated whether PAWP can induce fertilization-like Ca(2+) oscillations in mouse oocytes. Recombinant mouse PAWP protein was found to be unable to hydrolyse phosphatidylinositol 4,5-bisphosphate in vitro and did not cause any detectable Ca(2+) release when microinjected into mouse oocytes. Microinjection with cRNA encoding either the untagged PAWP, or yellow fluorescent protein (YFP)-PAWP, or luciferase-PAWP fusion proteins all failed to trigger Ca(2+) increases in mouse oocytes. The lack of response in mouse oocytes was despite PAWP being robustly expressed at similar or higher concentrations than PLCζ, which successfully initiated Ca(2+) oscillations in every parallel control experiment. These data suggest that sperm-derived PAWP is not involved in triggering Ca(2+) oscillations at fertilization in mammalian oocytes.
authors: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK mixosn@yahoo.com.
authors: Michail
authors: M
authors: Nomikos
authors: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
authors: Jessica R
authors: JR
authors: Sanders
authors: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK National Center for Scientific Research 'Demokritos', 15310 Aghia Paraskevi, Greece.
authors: Maria
authors: M
authors: Theodoridou
authors: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
authors: Junaid
authors: J
authors: Kashir
authors: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
authors: Emily
authors: E
authors: Matthews
authors: National Center for Scientific Research 'Demokritos', 15310 Aghia Paraskevi, Greece.
authors: George
authors: G
authors: Nounesis
authors: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
authors: F Anthony
authors: FA
authors: Lai
authors: Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK.
authors: Karl
authors: K
authors: Swann
mesh_terms: D000818:Animals; D001426:Bacterial Proteins; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002352:Carrier Proteins / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D008164:Luminescent Proteins; D008297:Male; D051379:Mice; D008845:Microinjections; D009865:Oocytes / Q000378:metabolism*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D054801:Phosphoinositide Phospholipase C / Q000008:administration & dosage / Q000378:metabolism*; D018075:RNA, Complementary / Q000008:administration & dosage / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000378:metabolism; D029589:Seminal Plasma Proteins / Q000008:administration & dosage / Q000378:metabolism*; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D008164:Luminescent Proteins; C519841:PAWP protein, mouse; D019269:Phosphatidylinositol 4,5-Diphosphate; D018075:RNA, Complementary; D011993:Recombinant Fusion Proteins; D029589:Seminal Plasma Proteins; C054562:yellow fluorescent protein, Bacteria; D015544:Inositol 1,4,5-Trisphosphate; D054801:Phosphoinositide Phospholipase C; D002118:Calcium
keywords: PAWP; PLCζ; fertilization; oocyte activation; sperm factor