Sperm deliver a new second messenger: NAADP.
NAADP is a highly potent mobilizer of Ca(2+), which in turn triggers Ca(2+)-induced Ca(2+) release pathways in a wide range of species. Nevertheless, NAADP is not presently classified as a second messenger because it has not been shown to increase in response to a physiological stimulus. We now report a dramatic increase in NAADP during sea urchin egg fertilization that was largely due to production in sperm upon contacting egg jelly. The NAADP bolus plays a physiological role upon delivery to the egg based on its ability to induce a cortical flash, a depolarization-induced activation of L-type Ca(2+) channels. Moreover, the sperm-induced cortical flash was eliminated in eggs desensitized to NAADP. We conclude that an NAADP increase plays a physiologically relevant role during fertilization and provides the first conclusive demonstration that NAADP is a genuine second messenger.
Churchill
Grant C
GC
Department of Pharmacology, University of Oxford, Mansfield Road, OX1 3QT, Oxford, United Kingdom. grant.churchill@pharm.ox.ac.uk
O'Neill
John S
JS
Masgrau
Roser
R
Patel
Sandip
S
Thomas
Justyn M
JM
Genazzani
Armando A
AA
Galione
Antony
A
D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020013:Calcium Signaling; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009249:NADP / Q000031:analogs & derivatives* / Q000378:metabolism*; D012617:Sea Urchins / Q000378:metabolism; D015290:Second Messenger Systems; D013084:Sperm-Ovum Interactions / Q000502:physiology; D013094:Spermatozoa / Q000378:metabolism*
D020746:Calcium Channels, L-Type; D009249:NADP; C024376:NAADP