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Lipid rafts function in Ca 2+ signaling responsible for activation of sperm motility and chemotaxis in the ascidian Ciona intestinalis
Author(s) -
Zhu Lihong,
Inaba Kazuo
Publication year - 2011
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.21382
Subject(s) - biology , chemotaxis , sperm , capacitation , microbiology and biotechnology , motility , ciona intestinalis , sperm motility , lipid raft , signal transduction , ciona , biochemistry , receptor , botany , gene
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. Mol. Reprod. Dev. 78:920–929, 2011. © 2011 Wiley Periodicals, Inc.

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