Cell Motil Cytoskeleton 1999 Jan 01;421:27-35. doi: 10.1002/(SICI)1097-0169(1999)42:1<27::AID-CM3>3.0.CO;2-L.

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

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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 phorbol13-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 microM, 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.

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Genes referenced: LOC100887844 LOC115919910 LOC590297