Ca(2+) entry through store-operated channels in mouse sperm is initiated by egg ZP3 and drives the acrosome reaction.
Fertilization occurs after the completion of the sperm acrosome reaction, a secretory event that is triggered during gamete adhesion. ZP3, an egg zona pellucida glycoprotein, produces a sustained increase of the internal Ca(2+) concentration in mouse sperm, leading to acrosome reactions. Here we show that the sustained Ca(2+) concentration increase is due to the persistent activation of a Ca(2+) influx mechanism during the late stages of ZP3 signal transduction. These cells also possess a Ca(2+) store depletion-activated Ca(2+) entry pathway that is open after treatment with thapsigargin. Thapsigargin and ZP3 activate the same Ca(2+) permeation mechanism, as demonstrated by fluorescence quenching experiments and by channel antagonists. These studies show that ZP3 generates a sustained Ca(2+) influx through a store depletion-operated pathway and that this drives the exocytotic acrosome reaction.
O'Toole
C M
CM
Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA.
Arnoult
C
C
Darszon
A
A
Steinhardt
R A
RA
Florman
H M
HM
D020101:Acrosome Reaction / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling; D002614:Chelating Agents / Q000494:pharmacology; D004527:Egg Proteins / Q000378:metabolism*; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D008345:Manganese / Q000378:metabolism / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D011956:Receptors, Cell Surface; D013075:Sperm Capacitation; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D019284:Thapsigargin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology; D000072216:Zona Pellucida Glycoproteins
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002614:Chelating Agents; D004527:Egg Proteins; D007476:Ionophores; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D000072216:Zona Pellucida Glycoproteins; C000606521:Zp3 protein, mouse; D008345:Manganese; D004533:Egtazic Acid; D015759:Ionomycin; D019284:Thapsigargin; D014700:Verapamil; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium