A monoclonal antibody to human SP-10 inhibits in vitro the binding of human sperm to hamster oolemma but not to human Zona pellucida.
SP-10 is a sperm intra-acrosomal protein, specific to the testis, that is believed to play an important role in egg-sperm binding. While the molecular characterization of the SP-10 protein has been clarified, little is yet known of its functional role in fertilization. We therefore established a monoclonal antibody (mAb pep-SP10) against a peptide (pep-SP10) that included the most hydrophilic portion of human SP-10 between the 135th and 149th amino acids. Human SP-10 was found to be localized in the equatorial region of acrosome-reacted sperm by immunofluorescent staining using our mAb pep-SP10. Monoclonal Ab pep-SP10 inhibited sperm-oolemma binding in the zona-free hamster egg penetration test, but it did not inhibit sperm-zona binding in the hemizona assay. Furthermore, we demonstrated that the oolemmal ligands of human SP-10 did not include beta(1) integrins, the most promising candidates for oocyte ligands involved in sperm-oolemma binding, based on the findings of a human sperm-cultured cell binding assay using F9 mouse embryonal carcinoma cells and F9-transformed cells lacking beta(1) integrins. In conclusion, our present data suggest that human SP-10, expressed on the equatorial region of acrosome-reacted sperm, indeed mediates sperm-oolemma binding in a beta(1) integrin-independent manner, but not sperm-zona binding.
Hamatani
T
T
Department of Obstetrics and Gynecology, School of Medicine, Keio University, Tokyo 160-8582, Japan.
Tanabe
K
K
Kamei
K
K
Sakai
N
N
Yamamoto
Y
Y
Yoshimura
Y
Y
D000177:Acrosome; D020101:Acrosome Reaction; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000941:Antigens; D015153:Blotting, Western; D018236:Carcinoma, Embryonal / Q000235:genetics; D002478:Cells, Cultured; D006224:Cricetinae; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods; D012739:Gonadal Steroid Hormones; D006801:Humans; D019012:Integrin beta1 / Q000235:genetics / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D011506:Proteins / Q000276:immunology* / Q000378:metabolism; D013084:Sperm-Ovum Interactions / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism*; D015044:Zona Pellucida / Q000187:drug effects / Q000378:metabolism*
C512729:ACRV1 protein, human; C080034:Acrv1 protein, mouse; D000911:Antibodies, Monoclonal; D000941:Antigens; D012739:Gonadal Steroid Hormones; D019012:Integrin beta1; D008565:Membrane Proteins; D011506:Proteins