title: Evidences of Biological Functions of Biliverdin Reductase A in the Bovine Epididymis.
abstract: Epididymal sperm binding protein 1 (ELSPBP1) is secreted by the epididymal epithelium via epididymosomes and is specifically transferred to dead spermatozoa during epididymal transit. We identified biliverdin reductase A (BLVRA) as a partner of ELSPBP1 by immunoprecipitation followed by tandem mass spectrometry. Pull down assays showed that these two proteins interact in the presence of zinc ions. The BLVRA enzyme is known to convert biliverdin to bilirubin, both of which possess antioxidant activity. Assessment by real-time RT-PCR showed that BLVRA is highly expressed in the caput and the corpus epididymis, but is expressed at lower levels in the testis and the cauda epididymis. It is primarily found in the soluble fraction of the caput epididymal fluid, is barely detectable in the cauda fluid, and is detectable to a lesser extent in the epididymosome fraction of both caput and cauda fluids. Immunocytometry on epididymal sperm showed that BLVRA is found on all sperm recovered from the caput region, whereas it is undetectable on cauda sperm. Biliverdin and bilirubin are found in higher concentrations in the caput epididymal fluid, as measured by mass spectrometry. Lipid peroxidation was limited by 1 μM of biliverdin, but not bilirubin when caput spermatozoa were challenged with 500 μM H2O2. Since immature spermatozoa are a source of reactive oxygen species, BLVRA may be involved in the protection of maturing spermatozoa. It is also plausible that BLVRA is implicated in haemic protein catabolism in the epididymal luminal environment.
authors.affiliation: Département d'obstétrique, gynécologie et reproduction, Faculté de Médecine, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Canada.
authors.forename: Olivier
authors.initials: O
authors.lastname: D'Amours
authors.affiliation: Département d'obstétrique, gynécologie et reproduction, Faculté de Médecine, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Canada.
authors.forename: Gilles
authors.initials: G
authors.lastname: Frenette
authors.affiliation: Laboratoire de pharmacogénomique, Faculté de Pharmacie, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Canada.
authors.forename: Patrick
authors.initials: P
authors.lastname: Caron
authors.affiliation: Département d'obstétrique, gynécologie et reproduction, Faculté de Médecine, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Canada.
authors.forename: Clémence
authors.initials: C
authors.lastname: Belleannée
authors.affiliation: Laboratoire de pharmacogénomique, Faculté de Pharmacie, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Canada.
authors.forename: Chantal
authors.initials: C
authors.lastname: Guillemette
authors.affiliation: Département d'obstétrique, gynécologie et reproduction, Faculté de Médecine, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Université Laval, Québec, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Sullivan
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001663:Bilirubin / Q000378:metabolism; D001664:Biliverdine / Q000378:metabolism; D015153:Blotting, Western; D001826:Body Fluids / Q000378:metabolism; D002417:Cattle; D002853:Chromatography, Liquid; D004822:Epididymis / Q000201:enzymology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008297:Male; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D029589:Seminal Plasma Proteins / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D013737:Testis / Q000201:enzymology; D015032:Zinc / Q000378:metabolism
chemical_list: D000975:Antioxidants; D011994:Recombinant Proteins; D029589:Seminal Plasma Proteins; D006861:Hydrogen Peroxide; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019789:biliverdin reductase; D015032:Zinc; D001664:Biliverdine; D001663:Bilirubin