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) Supplemental Files (videos) Supplemental Data (Videos) All Versions of this Article: 73/3/519    most recent biolreprod.105.040733v1 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 Ignotz, G. G. Articles by Suarez, S. S. Search for Related Content PubMed PubMed Citation Articles by Ignotz, G. G. Articles by Suarez, S. S. Agricola Articles by Ignotz, G. G. Articles by Suarez, S. S.

Calcium/Calmodulin and Calmodulin Kinase II Stimulate Hyperactivation in Demembranated Bovine Sperm¹

Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853

Hyperactivated motility is observed among sperm in the mammalian oviduct near the time of ovulation. It is characterized by high-amplitude, asymmetrical flagellar beating and assists sperm in penetrating the cumulus oophorus and zona pellucida. Elevated intracellular Ca²⁺ is required for the initiation of hyperactivated motility, suggesting that calmodulin (CALM) and Ca²⁺/CALM-stimulated pathways are involved. A demembranated sperm model was used to investigate the role of CALM in promoting hyperactivation. Ejaculated bovine sperm were demembranated and immobilized by brief exposure to Triton X-100. Motility was restored by addition of reactivation medium containing MgATP and Ca²⁺, and hyperactivation was observed as free Ca²⁺ was increased from 50 nM to 1 µM. However, when 2.5 mM Ca²⁺ was added to the demembranation medium to extract flagellar CALM, motility was not reactivated unless exogenous CALM was readded. The inclusion of anti-CALM IgG in the reactivation medium reduced the proportion hyperactivated in 1 µM Ca²⁺ to 5%. Neither control IgG, the CALM antagonist W-7, nor a peptide directed against the CALM-binding domain of myosin light chain kinase (MYLK2) inhibited hyperactivation. However, when sperm were reactivated in the presence of CALM kinase II (CAMK2) inhibiting peptides, hyperactivation was reduced by 75%. Furthermore, an inhibitor of CAMK2, KN-93, inhibited hyperactivation without impairing normal motility of intact sperm. CALM and CAMK2 were immunolocalized to the acrosomal region and flagellum. These results indicate that hyperactivation is stimulated by a Ca²⁺/CALM pathway involving CAMK2.

calcium, gamete biology, male reproductive tract, sperm motility and transport

² Correspondence: Susan S. Suarez, Department of Biomedical Sciences, Cornell University, T5-002B Veterinary Research Tower, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853. FAX: 607 253 3541; sss7{at}cornell.edu

This article has been cited by other articles:

				S. S. Suarez Control of hyperactivation in sperm Hum. Reprod. Update, November 1, 2008; 14(6): 647 - 657. [Abstract] [Full Text] [PDF]

				K. Schlingmann, M. A. Michaut, J. L. Mcelwee, C. A. Wolff, A. J. Travis, and R. M. Turner Calmodulin and CaMKII in the Sperm Principal Piece: Evidence for a Motility-Related Calcium/Calmodulin Pathway J Androl, September 1, 2007; 28(5): 706 - 716. [Abstract] [Full Text] [PDF]

				B. Marquez and S. S. Suarez Bovine Sperm Hyperactivation Is Promoted by Alkaline-Stimulated Ca2+ Influx Biol Reprod, April 1, 2007; 76(4): 660 - 665. [Abstract] [Full Text] [PDF]