Egg coat proteins activate calcium entry into mouse sperm via CATSPER channels.
During mammalian fertilization, the contact between sperm and egg triggers increases in intracellular Ca(2+) concentration ([Ca(2+)](i)) in sperm. Voltage-gated Ca(2+) channels (Ca(V)s) are believed to mediate the initial phase of [Ca(2+)](i) increases in sperm induced by egg coat (zona pellucida [ZP]) glycoproteins, while store depletion-activated Ca(2+) entry is thought to mediate the sustained phase. Using patch-clamp recording and Ca(2+) imaging, we show herein that Ca(V) channel currents, while found in spermatogenic cells, are not detectable in epididymal sperm and are not essential for the ZP-induced [Ca(2+)](i) changes. Instead, CATSPER channels localized in the distal portion of sperm (the principal piece) are required for the ZP-induced [Ca(2+)](i) increases. Furthermore, the ZP-induced [Ca(2+)](i) increase starts from the sperm tail and propagates toward the head.
Xia
Jingsheng
J
Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Ren
Dejian
D
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D004527:Egg Proteins / Q000378:metabolism; D004822:Epididymis; D005260:Female; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018408:Patch-Clamp Techniques; D011956:Receptors, Cell Surface / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism*; D015044:Zona Pellucida / Q000378:metabolism*; D000072216:Zona Pellucida Glycoproteins
D015220:Calcium Channels; C488642:Catsper1 protein, mouse; D004527:Egg Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins; D002118:Calcium