Nicotinic acid adenine dinucleotide phosphate-induced Ca(2+) release. Interactions among distinct Ca(2+) mobilizing mechanisms in starfish oocytes.
An intracellular mechanism activated by nicotinic acid adenine dinucleotide phosphate (NAADP(+)) contributes to intracellular Ca(2+) release alongside inositol 1,4,5-trisphosphate (Ins-P(3)) and ryanodine receptors. The NAADP(+)-sensitive mechanism has been shown to be operative in sea urchin eggs, ascidian eggs, and pancreatic acinar cells. Furthermore, most mammalian cell types can synthesize NAADP(+), with nicotinic acid and NADP(+) as precursors. In this contribution, NAADP(+)-induced Ca(2+) release has been investigated in starfish oocytes. Uncaging of injected NAADP(+) induced Ca(2+) mobilization in both immature oocytes and in oocytes matured by the hormone 1-methyladenine (1-MA). The role of extracellular Ca(2+) in NAADP(+)-induced Ca(2+) mobilization, which was minor in immature oocytes, was instead essential in mature oocytes. Thus, the NAADP(+)-sensitive Ca(2+) pool, which is known to be distinct from those sensitive to inositol 1,4,5-trisphosphate or cyclic ADPribose, apparently migrated closer to (or became part of) the plasma membrane during the maturation process. Inhibition of both Ins-P(3) and ryanodine receptors, but not of either alone, substantially inhibited NAADP(+)-induced Ca(2+) mobilization in both immature and mature oocytes. The data also suggest that NAADP(+)-induced Ca(2+) mobilization acted as a trigger for Ca(2+) release via Ins-P(3) and ryanodine receptors.
Santella
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Laboratory of Cell Biology Stazione Zoologica "A. Dohrn" Villa Comunale, I-80121, Napoli, Italy.
Kyozuka
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K
Genazzani
A A
AA
De Riso
L
L
Carafoli
E
E
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling; D009249:NADP / Q000031:analogs & derivatives* / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D013215:Starfish
D002121:Calcium Channel Blockers; C008407:1-methyladenine; D009249:NADP; C024376:NAADP; D000225:Adenine