NAADP+ initiates the Ca2+ response during fertilization of starfish oocytes

Dmitri Lim, Keiichiro Kyozuka, Giovanni Gragnaniell, Ernesto Carafoli, Luigia Santella

Research output: Contribution to journalArticlepeer-review

81 Citations (Scopus)

Abstract

We have explored the role of the recently discovered second messenger nicotinic acid adenine nucleotide phosphate (NAADP+) in Ca2+ swings that accompany the fertilization process in starfish oocytes. The injection of NAADP+ deep into the cytoplasm of oocytes matured by the hormone 1-methyladenine (1-MA), mobilized Ca2+ exclusively in the cortical layer, showing that the NAADP+-sensitive Ca2+ pool is restricted to the subplasma membrane region of the cell. At variance with this, InsP3 initiated the liberation of Ca2+ next to the point of injection in the center of the cell. The initial cortical Ca2+ liberation induced by NAADP+ was followed by a spreading of the Ca2+ wave to the remainder of the cell and by a massive cortical granule exocytosis similar to that routinely observed on injection of InsP3. A striking difference in the responses to NAADP+ and InsP3 was revealed by the removal of the nucleus from immature oocytes, i.e., from oocytes not treated with 1-MA. Whereas the Ca2+ response and the cortical granule exocytosis induced by NAADP+ were unaffected by the removal of the nucleus, the Ca2+ response promoted by InsP3 was significantly slowed. In addition, the cortical granule exocytosis was completely abolished. When enucleated oocytes were fertilized, the spermatozoon still promoted the Ca2+ wave and normal cortical exocytosis, strongly suggesting that the Ca2+ response was mediated by NAADP+ and not by InsP3. InsP3-sensitive Ca2+ stores may mediate the propagation of the wave initiated by NAADP+ since its spreading was strongly affected by removal of the nucleus.

Original languageEnglish
Pages (from-to)2257-2267
Number of pages11
JournalFASEB Journal
Volume15
Issue number12
DOIs
Publication statusPublished - 2001 Oct 16

Keywords

  • Ca response at fertilization
  • Inositol 1,4,5-trisphosphate
  • Nicotinic acid adenine nucleotide phosphate
  • Starfish oocytes

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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