Cytoplasmic Ca2+ oscillation coordinates the formation of actin filaments in the sea urchin eggs activated with phorbol ester

Akio Arai, Keiichiro Kyozuka, Tohru Nakazawa

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Changes in the intracellular Ca2+ concentration ([Ca2+]i) and the formation of actin filaments were investigated in unfertilized eggs of the sea urchin Hemicentrotus pulcherrimus after activation with a phorbol ester, 12-O-tetradecanoyl phorbol-13-acetate (TPA). Intracellular Ca2+ oscillation was observed using a fluorescent Ca2+ indicator dye, calcium green dextran. From about 20 to 80 min after the addition of TPA to 100 μM, there was a rise in [Ca2+]i, which was followed by Ca2+ oscillation. A change in [Ca2+]i in response to TPA was not observed in eggs that had been injected with heparin, an inositol 1,4,5-triphosphate (IP3) receptor antagonist. Therefore, long-term exposure to a high concentration of TPA seems to induce Ca2+ release via the IP3 pathway, as well as causing the release of diacylglycerol from membrane lipids. Moreover, the elongation of actin filaments occurred in the cytoplasm during the rise in [Ca2+]i. Actin filaments also formed when TPA-induced cytoplasmic alkalization was inhibited by exposure to Na+free sea water. These results suggest that the observed cytoplasmic formation of actin filaments may be related to change in the cytoplasmic [Ca2+]i, and not intracellular pH, induced by TPA. These phenomena may be similar to the changes in actin construction that occur during cell cycle events.

Original languageEnglish
Pages (from-to)27-35
Number of pages9
JournalCell Motility and the Cytoskeleton
Volume42
Issue number1
DOIs
Publication statusPublished - 1999

Keywords

  • Actin filaments
  • Calcium
  • InositoI 1,4,5- triphosphate
  • PH
  • Phorbol ester
  • Sea urchin egg

ASJC Scopus subject areas

  • Structural Biology
  • Cell Biology

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