Journal of Andrology, Vol 17, Issue 5 522-529, Copyright © 1996 by The American Society of Andrology

JOURNAL ARTICLE

Voltage-dependent calcium channels and Gi regulatory protein mediate the human sperm acrosomal exocytosis induced by N-acetylglucosaminyl/mannosyl neoglycoproteins

A. Brandelli, P. V. Miranda and J. G. Tezon
Departamento de Bioquimica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.

Mammalian spermatozoa must undergo an exocytotic event during fertilization, the acrosome reaction (AR). In most species studied this process is induced by specific glycoproteins of the oocyte extracellular matrix, the zona pellucida (ZP), and it involves guanine nucleotide-binding regulatory proteins (G-proteins), resulting in an uptake of extracellular calcium by the sperm. In the bull, this event has been reported to be mediated by voltage-dependent calcium channels (VDCC). Previous observations showed that neoglycoproteins (NGPs) with N-acetylglucosamine or mannose (GlcNAc-BSA or Man-BSA) residues induce the AR in capacitated human spermatozoa. We report here that the pretreatment of spermatozoa with 125 ng/ml pertussis toxin (PTx) inhibited GlcNAc-BSA- or Man-BSA-induced AR, whereas 1 microgram/ml cholera toxin had no effect. These data indicate that the transduction mechanism for GlcNAc-BSA- and Man-BSA-induced AR involves G-proteins of the inhibitory type (GI). An increase in the AR rate was observed when capacitated spermatozoa were incubated with increasing concentrations of potassium ions (K+) in Biggers-Whitten-Whittingham (BWW) modified medium (2.6 +/- 0.3-fold at 80 mM K+). This induction was observed only when the pH was raised to 8.5, and it was inhibited by verapamil, nitrendipine, omega-conotoxin, nickel ions (Ni2+), lanthanum ions (La3+), or cadmium ions (Cd2+) in a concentration-dependent manner, indicating the participation of VDCC activated by membrane depolarization. The GlcNAc-BSA- or Man-BSA-induced AR was completely inhibited by preincubation of spermatozoa with VDCC blockers and calcium antagonists, indicating a link between the binding of sugar residues of the NGPs and channel activation. The AR induced by membrane depolarization with high K+ medium was not inhibited by PTx, suggesting that Ca2+ entry is downstream to GI-protein activation. These data show that the induction of the AR in human spermatozoa by GlcNAc- or Man-NGPs involves VDCC and GI-like regulatory proteins similar to the induction described for ZP in other mammalian species.

This article has been cited by other articles:

				H. L. Feng, Y. B. Han, A. Hershlag, and L. J. Zheng Impact of Ca2+ Flux Inhibitors on Acrosome Reaction of Hamster Spermatozoa J Androl, July 1, 2007; 28(4): 561 - 564. [Abstract] [Full Text] [PDF]

				K. Zitta, E. Wertheimer, and P. V. Miranda Analysis of the participation of N-acetylglucosamine in the different steps of sperm-zona pellucida interaction in hamster Mol. Hum. Reprod., December 1, 2004; 10(12): 925 - 933. [Abstract] [Full Text] [PDF]

				P.C.N. Chiu, H.Y. Tsang, R. Koistinen, H. Koistinen, M. Seppala, K.F. Lee, and W.S.B. Yeung The Contribution of D-Mannose, L-Fucose, N-Acetylglucosamine, and Selectin Residues on the Binding of Glycodelin Isoforms to Human Spermatozoa Biol Reprod, June 1, 2004; 70(6): 1710 - 1719. [Abstract] [Full Text] [PDF]

				J. C. Kirkman-Brown, E. L. Punt, C. L. R. Barratt, and S. J. Publicover Zona Pellucida and Progesterone-Induced Ca2+ Signaling and Acrosome Reaction in Human Spermatozoa J Androl, May 1, 2002; 23(3): 306 - 315. [Full Text] [PDF]

				S. Jagannathan, E. L. Punt, Y. Gu, C. Arnoult, D. Sakkas, C. L. R. Barratt, and S. J. Publicover Identification and Localization of T-type Voltage-operated Calcium Channel Subunits in Human Male Germ Cells. EXPRESSION OF MULTIPLE ISOFORMS J. Biol. Chem., March 1, 2002; 277(10): 8449 - 8456. [Abstract] [Full Text] [PDF]

				W.-Y. Son, J.-H. Lee, J.-H. Lee, and C.-T. Han Acrosome reaction of human spermatozoa is mainly mediated by {alpha}1H T-type calcium channels Mol. Hum. Reprod., October 1, 2000; 6(10): 893 - 897. [Abstract] [Full Text] [PDF]

				P. V. Miranda, F. Gonzalez-Echeverria, J. A. Blaquier, D. J. Mahuran, and J. G. Tezon Evidence for the participation of {beta}-hexosaminidase in human sperm-zona pellucida interaction in vitro Mol. Hum. Reprod., August 1, 2000; 6(8): 699 - 706. [Abstract] [Full Text] [PDF]

				C. R. Loeser, C. I. Lynch, and D. R.P. Tulsiani Characterization of the Pharmacological-Sensitivity Profile of Neoglycoprotein-Induced Acrosome Reaction in Mouse Spermatozoa Biol Reprod, September 1, 1999; 61(3): 629 - 634. [Abstract] [Full Text]

				P. F. Blackmore and S. Eisoldt The neoglycoprotein mannose–bovine serum albumin, but not progesterone, activates T-type calcium channels in human spermatozoa Mol. Hum. Reprod., June 1, 1999; 5(6): 498 - 506. [Abstract] [Full Text] [PDF]

				A. Darszon, P. Labarca, T. Nishigaki, and F. Espinosa Ion Channels in Sperm Physiology Physiol Rev, April 1, 1999; 79(2): 481 - 510. [Abstract] [Full Text] [PDF]

				G. Wennemuth, R. E. Westenbroek, T. Xu, B. Hille, and D. F. Babcock CaV2.2 and CaV2.3 (N- and R-type) Ca2+ Channels in Depolarization-evoked Entry of Ca2+ into Mouse Sperm J. Biol. Chem., July 7, 2000; 275(28): 21210 - 21217. [Abstract] [Full Text] [PDF]