Characterization of the pharmacological-sensitivity profile of neoglycoprotein-induced acrosome reaction in mouse spermatozoa.
Mammalian spermatozoa undergo the acrosome reaction (AR) in response to the interaction of a carbohydrate-recognizing molecule(s) on the sperm plasma membrane (sperm surface receptor) and its complementary glycan (ligand) moiety(ies) on the zona pellucida (ZP). Previously, we demonstrated that a hexose (mannose) or two amino sugars (glucosaminyl or galactosaminyl residues) when covalently conjugated to a protein backbone (neoglycoproteins) mimicked the mouse ZP3 glycoprotein and induced the AR in capacitated mouse spermatozoa (Loeser and Tulsiani, Biol Reprod 1999; 60:94-101). To elucidate the mechanism underlying sperm-neoglycoprotein interaction and the induction of the AR, we have examined the effect of several AR blockers on neoglycoprotein-induced AR. Our data demonstrate that two known L-type Ca(2+) channel blockers prevented the induction of the AR by three neoglycoproteins (mannose-BSA, N-acetylglucosamine-BSA, and N-acetylgalactosamine-BSA). The fact that the L-type Ca(2+) channel blockers (verapamil, diltiazem) had no inhibitory effect on sperm surface galactosyltransferase or alpha-D-mannosidase, two carbohydrate-recognizing enzymes thought to be sperm surface receptors, suggests that the reagents block the AR by a mechanism other than binding to the active site of the enzymes.
Loeser
C R
CR
Center for Reproductive Biology Research and Departments of Obstetrics and Gynecology and Cell Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2633, USA.
Lynch
C
C
Tulsiani
D R
DR
D020101:Acrosome Reaction / Q000187:drug effects*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D004110:Diltiazem / Q000494:pharmacology; D005964:Glucosyltransferases / Q000378:metabolism; D006023:Glycoproteins / Q000494:pharmacology*; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008361:Mannosidases / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D013075:Sperm Capacitation; D013094:Spermatozoa / Q000201:enzymology; D014700:Verapamil / Q000494:pharmacology; D043323:alpha-Mannosidase
D002121:Calcium Channel Blockers; D006023:Glycoproteins; D007476:Ionophores; D000001:Calcimycin; D014700:Verapamil; D005964:Glucosyltransferases; D008361:Mannosidases; D043323:alpha-Mannosidase; D004110:Diltiazem