title: Protein kinase C is an important signaling mediator associated with motility of intact sea urchin spermatozoa.
abstract: Numerous kinases and phosphatases are most likely implicated in sperm motility initiation and maintenance. Data on these signaling molecules were mostly obtained from studies conducted on in vitro demembranated-reactivated sperm models but are not necessarily representative of the in vivo situation. We therefore investigated the effect of a variety of cell-permeable chemicals, mostly kinase inhibitors, on the motility initiation and maintenance of intact sea urchin spermatozoa. Among the 20 substances tested, the protein kinase C (PKC) inhibitor chelerythrine was the most potent, arresting motility at concentrations starting from 1.5-2 mumol l(-1). Motility was also inhibited by two other PKC inhibitors as well as staurosporine. Furthermore, these inhibitors prevented the motility-associated increase in phosphorylation of at least four PKC substrates. These phospho-PKC target proteins, as assessed with an antibody specific to phosphorylated motifs of PKC substrates, were found to be associated with the flagellum, either in the Triton X-100 soluble portion or the axoneme (Triton X-100 insoluble). A phosphorylated PKC-like enzyme was also detected by immunoblotting in the flagellum, as well as a significant 50 kDa PKC cleavage product. Taken together, the data strongly indicate for the first time that, in vivo, which means on intact spermatozoa, PKC is a key signaling mediator associated with the maintenance of sea urchin sperm motility.
authors.affiliation: Urology Research Laboratory, Royal Victoria Hospital, McGill University Health Center and Faculty of Medicine, McGill University, Montréal, H3A 1A1, Canada. dan7white@yahoo.ca
authors.forename: Daniel
authors.initials: D
authors.lastname: White
authors.forename: Eve
authors.initials: E
authors.lastname: de Lamirande
authors.forename: Claude
authors.initials: C
authors.lastname: Gagnon
mesh_terms: D000818:Animals; D005591:Chemical Fractionation; D006801:Humans; D008297:Male; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D012617:Sea Urchins / Q000187:drug effects / Q000201:enzymology*; D015398:Signal Transduction / Q000187:drug effects; D013081:Sperm Motility / Q000187:drug effects / Q000502:physiology*; D013094:Spermatozoa / Q000187:drug effects / Q000201:enzymology*; D013379:Substrate Specificity / Q000187:drug effects; D013997:Time Factors
chemical_list: D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D011493:Protein Kinase C