NAADP mobilizes Ca(2+) from reserve granules, lysosome-related organelles, in sea urchin eggs.
Nicotinic acid adenine dinucleotide phosphate (NAADP) mobilizes Ca(2+) in many cells and species. Unlike other Ca(2+)-mobilizing messengers, NAADP mobilizes Ca(2+) from an unknown store that is not the endoplasmic reticulum, the store traditionally associated with messenger-mediated Ca(2+) signaling. Here, we demonstrate the presence of a Ca(2+) store in sea urchin eggs mobilized by NAADP that is dependent on a proton gradient maintained by an ATP-dependent vacuolar-type proton pump. Moreover, we provide pharmacological and biochemical evidence that this Ca(2+) store is the reserve granule, the functional equivalent of a lysosome in the sea urchin egg. These findings represent an unsuspected mechanism for messenger-mediated Ca(2+) release from lysosome-related organelles.
Churchill
Grant C
GC
Department of Pharmacology, University of Oxford, Mansfield Road, OX1 3QT, Oxford, United Kingdom. grant.churchill@pharm.ox.ac.uk
Okada
Yuhei
Y
Thomas
Justyn M
JM
Genazzani
Armando A
AA
Patel
Sandip
S
Galione
Antony
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D008247:Lysosomes / Q000378:metabolism*; D008954:Models, Biological; D009249:NADP / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D015388:Organelles / Q000378:metabolism*; D010063:Ovum / Q000166:cytology / Q000378:metabolism*; D017494:Proton Pumps; D012617:Sea Urchins
D017494:Proton Pumps; D009249:NADP; C024376:NAADP; D002118:Calcium