HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal My Folders Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dorval, V. Articles by Leclerc, P. Search for Related Content PubMed PubMed Citation Articles by Dorval, V. Articles by Leclerc, P. Agricola Articles by Dorval, V. Articles by Leclerc, P.

Regulation of the Phosphotyrosine Content of Human Sperm Proteins by Intracellular Ca²⁺: Role of Ca²⁺-Adenosine Triphosphatases¹

^a Département d'Obstétrique/Gynécologie and Centre de recherche en Biologie de la Reproduction, Université Laval, and Centre de recherche du CHUQ, Québec, Québec, Canada G1L 3L5 ^b Centre de recherche du CHUL, Québec, Québec, Canada G1V 4G2

An increase in the concentration of intracellular free Ca²⁺ and in the phosphotyrosine content of specific proteins characterizes human sperm capacitation. Whether tyrosine phosphorylation regulates the intracellular free Ca²⁺ concentration through modulation of Ca²⁺-ATPase activity or the phosphotyrosine content is under Ca²⁺ regulation was investigated using Ca²⁺-ATPase modulators and tyrosine kinase inhibitors. The presence of the Ca²⁺-ATPase-inhibitor thapsigargin during human sperm capacitation caused an increase in the cytoplasmic free Ca²⁺ concentration and was associated with an increase in the phosphotyrosine content of specific sperm proteins. Conversely, a decrease in protein tyrosine phosphorylation was observed when gingerol, a Ca²⁺-ATPase activator, was present during the incubation period. On the other hand, thapsigargin had no effect on the phosphotyrosine content or the cytoplasmic Ca²⁺ concentration when spermatozoa were incubated in the presence of the phosphodiesterase-inhibitor 3-isobutyl-1-methylxanthine (IBMX). However, the effect of IBMX on phosphotyrosine-containing proteins appears to be a Ca²⁺-dependent phenomenon, because it was partly inhibited in spermatozoa pretreated with 1,2-bis-(o-aminophenoxy)-ethane-N,N,N,N-tetraacetic acid tetra-(acetoxymethyl)-ester (BAPTA-AM) even though, by itself, BAPTA-AM caused an increase in sperm protein phosphotyrosine content. Tyrosine kinase inhibitors prevented the increase in the phosphotyrosine content without affecting the cytoplasmic free Ca²⁺ concentration. Based on these findings, the present study suggests that Ca²⁺-ATPases are involved in the filling of internal Ca²⁺ stores, such as the acrosome, and are inhibited later during capacitation. Their inhibition allows an increase in cytoplasmic free Ca²⁺, which is involved in the subsequent increase in the phosphotyrosine content of specific sperm proteins.

¹ Supported by a grant from Canadian Institutes of Health Research (to P.L.), a studentship from Fonds pour la Formation de Chercheurs et Aide à la Recherche (to V.D.), and a scholarship from Fonds de la Recherche en Santé du Québec (to P.L.).

² Correspondence: Pierre Leclerc, Endocrinologie de la Reproduction, Pav. St-François d'Assise, 10 de L'Espinay, Québec, PQ, Canada G1L 3L5.> FAX: 418 525 4195; pierre.leclerc{at}crsfa.ulaval.ca

This article has been cited by other articles:

				A. Barbonetti, M.R.C. Vassallo, B. Cinque, C. Antonangelo, F. Sciarretta, R. Santucci, A. D'Angeli, S. Francavilla, and F. Francavilla Dynamics of the Global Tyrosine Phosphorylation During Capacitation and Acquisition of the Ability to Fuse with Oocytes in Human Spermatozoa Biol Reprod, October 1, 2008; 79(4): 649 - 656. [Abstract] [Full Text] [PDF]

				C. Lawson, S. Goupil, and P. Leclerc Increased Activity of the Human Sperm Tyrosine Kinase SRC by the cAMP-Dependent Pathway in the Presence of Calcium Biol Reprod, October 1, 2008; 79(4): 657 - 666. [Abstract] [Full Text] [PDF]

				C. Lachance, J. L. Bailey, and P. Leclerc Expression of Hsp60 and Grp78 in the human endometrium and oviduct, and their effect on sperm functions Hum. Reprod., October 1, 2007; 22(10): 2606 - 2614. [Abstract] [Full Text] [PDF]

				C. Lawson, V. Dorval, S. Goupil, and P. Leclerc Identification and localisation of SERCA 2 isoforms in mammalian sperm Mol. Hum. Reprod., May 1, 2007; 13(5): 307 - 316. [Abstract] [Full Text] [PDF]

				J. Laflamme, A. Akoum, and P. Leclerc Induction of human sperm capacitation and protein tyrosine phosphorylation by endometrial cells and interleukin-6 Mol. Hum. Reprod., February 1, 2005; 11(2): 141 - 150. [Abstract] [Full Text] [PDF]

				V. Nauc, E. De Lamirande, P. Leclerc, and C. Gagnon Inhibitors of Phosphoinositide 3-Kinase, LY294002 and Wortmannin, Affect Sperm Capacitation and Associated Phosphorylation of Proteins Differently: Ca2+-Dependent Divergences J Androl, July 1, 2004; 25(4): 573 - 585. [Abstract] [Full Text] [PDF]

				R E Spindler, Y Huang, J G Howard, P Wang, H Zhang, G Zhang, and D E Wildt Acrosomal integrity and capacitation are not influenced by sperm cryopreservation in the giant panda Reproduction, May 1, 2004; 127(5): 547 - 556. [Abstract] [Full Text] [PDF]

				M. A. Baker, L. Hetherington, H. Ecroyd, S. D. Roman, and R. J. Aitken Analysis of the mechanism by which calcium negatively regulates the tyrosine phosphorylation cascade associated with sperm capacitation J. Cell Sci., January 15, 2004; 117(2): 211 - 222. [Abstract] [Full Text] [PDF]

				K. P. Roberts, J. A. Wamstad, K. M. Ensrud, and D. W. Hamilton Inhibition of Capacitation-Associated Tyrosine Phosphorylation Signaling in Rat Sperm by Epididymal Protein Crisp-1 Biol Reprod, August 1, 2003; 69(2): 572 - 581. [Abstract] [Full Text] [PDF]

				V. Dorval, M. Dufour, and P. Leclerc Role of protein tyrosine phosphorylation in the thapsigargin-induced intracellular Ca2+ store depletion during human sperm acrosome reaction Mol. Hum. Reprod., March 1, 2003; 9(3): 125 - 131. [Abstract] [Full Text] [PDF]