Actin cytoskeleton modulates calcium signaling during maturation of starfish oocytes

Keiichiro Kyozuka, Jong T. Chun, Agostina Puppo, Gianni Gragnaniello, Ezio Garante, Luigia Santella

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)

Abstract

Before successful fertilization can occur, oocytes must undergo meiotic maturation. In starfish, this can be achieved in vitro by applying 1-methyladenine (1-MA). The immediate response to 1-MA is the fast Ca2+ release in the cell cortex. Here, we show that this Ca2+ wave always initiates in the vegetal hemisphere and propagates through the cortex, which is the space immediately under the plasma membrane. We have observed that alteration of the cortical actin cytoskeleton by latrunculin-A and jasplakinolide can potently affect the Ca2+ waves triggered by 1-MA. This indicates that the cortical actin cytoskeleton modulates Ca2+ release during meiotic maturation. The Ca2+ wave was inhibited by the classical antagonists of the InsP3-linked Ca2+ signaling pathway, U73122 and heparin. To our surprise, however, these two inhibitors induced remarkable actin hyper-polymerization in the cell cortex, suggesting that their inhibitory effect on Ca2+ release may be attributed to the perturbation of the cortical actin cytoskeleton. In post-meiotic eggs, U73122 and jasplakinolide blocked the elevation of the vitelline layer by uncaged InsP3, despite the massive release of Ca2+, implying that exocytosis of the cortical granules requires not only a Ca2+ rise, but also regulation of the cortical actin cytoskeleton. Our results suggest that the cortical actin cytoskeleton of starfish oocytes plays critical roles both in generating Ca2+ signals and in regulating cortical granule exocytosis.

Original languageEnglish
Pages (from-to)426-435
Number of pages10
JournalDevelopmental Biology
Volume320
Issue number2
DOIs
Publication statusPublished - 2008 Aug 15

Keywords

  • 1-methyladenine
  • Actin
  • Cortical granule exocytosis
  • Cytoskeleton
  • Heparin
  • InsP
  • Meiosis
  • Oocyte
  • Starfish
  • U73122

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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