RRC ID 30197
Author Zhu L, Inaba K.
Title Lipid rafts function in Ca2+ signaling responsible for activation of sperm motility and chemotaxis in the ascidian Ciona intestinalis.
Journal Mol Reprod Dev
Abstract Lipid rafts are specialized membrane microdomains that function as signaling platforms across plasma membranes of many animal and plant cells. Although there are several studies implicating the role of lipid rafts in capacitation of mammalian sperm, the function of these structures in sperm motility activation and chemotaxis remains unknown. In the ascidian Ciona intestinalis, egg-derived sperm activating- and attracting-factor (SAAF) induces both activation of sperm motility and sperm chemotaxis to the egg. Here we found that a lipid raft disrupter, methyl-β-cyclodextrin (MCD), inhibited both SAAF-induced sperm motility activation and chemotaxis. MCD inhibited both SAAF-promoted synthesis of intracellular cyclic AMP and sperm motility induced by ionophore-mediated Ca(2+) entry, but not that induced by valinomycin-mediated hyperpolarization. Ca(2+)-imaging revealed that lipid raft disruption inhibited Ca(2+) influx upon activation of sperm motility. The Ca(2+)-activated adenylyl cyclase was clearly inhibited by MCD in isolated lipid rafts. The results suggest that sperm lipid rafts function in signaling upstream of cAMP synthesis, most likely in SAAF-induced Ca(2+) influx, and are required for Ca(2+)-dependent pathways underlying activation and chemotaxis in Ciona sperm.
Volume 78(12)
Pages 920-9
Published 2011-12-1
DOI 10.1002/mrd.21382
PMID 21887722
MeSH Adenylyl Cyclases / metabolism Animals Calcium / metabolism Calcium Signaling / drug effects Calcium Signaling / physiology* Chemotaxis / drug effects Chemotaxis / physiology* Ciona intestinalis / cytology Ciona intestinalis / physiology* Cyclic AMP / metabolism Intracellular Space / metabolism Male Membrane Microdomains / drug effects Membrane Microdomains / metabolism* Sperm Motility / drug effects Sperm Motility / physiology* Theophylline / pharmacology Valinomycin / antagonists & inhibitors Valinomycin / pharmacology beta-Cyclodextrins / pharmacology
IF 2.823
Times Cited 9
C.intestinalis / (O.japonicus) Wild C. int