NAADP and InsP3 play distinct roles at fertilization in starfish oocytes

Francesco Moccia, Gilda A. Nusco, Dmitry Lim, Keiichiro Kyozuka, Luigia Santella

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

NAADP participates in the response of starfish oocytes to sperm by triggering the fertilization potential (FP) through the activation of a Ca2+ current which depolarizes the membrane to the threshold of activation of the voltage-gated Ca2+ channels. The aim of this study was to investigate whether this Ca2+ influx is linked to the onset of the concomitant InsP3-mediated Ca2+ wave by simultaneously employing Ca2+ imaging and single-electrode intracellular recording techniques. In control oocytes, the sperm-induced membrane depolarization always preceded by a few seconds the onset of the Ca2+ wave. Strikingly, the self-desensitization of NAADP receptors either abolished the Ca2+ response or resulted in abnormal oocyte activation, i.e., the membrane depolarization followed the Ca2+ wave and the oocyte was polyspermic. The inhibition of InsP3 signaling only impaired the propagation of the Ca2+ wave and shortened the FP. The duration of FP was also reduced in low-Na+ sea water. Finally, uncaged InsP3 produced a Ca2+ increase, which depolarized the membrane upon the activation of a Ca2+-sensitive cation current. These results support the hypothesis that Ca2+ entry during the NAADP-triggered FP is required for the onset of the Ca2+ wave at fertilization. The InsP3-mediated Ca2+ wave, in turn, may interact with the NAADP-evoked depolarization by activating a Ca2+-dependent Na+ entry.

Original languageEnglish
Pages (from-to)24-38
Number of pages15
JournalDevelopmental Biology
Volume294
Issue number1
DOIs
Publication statusPublished - 2006 Jun 1

Keywords

  • Ca wave
  • Fertilization
  • InsP
  • NAADP
  • Oocytes
  • Sperm
  • Starfish

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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