TY - JOUR
T1 - Cytoplasmic Ca2+ oscillation coordinates the formation of actin filaments in the sea urchin eggs activated with phorbol ester
AU - Arai, Akio
AU - Kyozuka, Keiichiro
AU - Nakazawa, Tohru
PY - 1999
Y1 - 1999
N2 - 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.
AB - 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.
KW - Actin filaments
KW - Calcium
KW - InositoI 1,4,5- triphosphate
KW - PH
KW - Phorbol ester
KW - Sea urchin egg
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U2 - 10.1002/(SICI)1097-0169(1999)42:1<27::AID-CM3>3.0.CO;2-L
DO - 10.1002/(SICI)1097-0169(1999)42:1<27::AID-CM3>3.0.CO;2-L
M3 - Article
C2 - 9915582
AN - SCOPUS:0032590003
VL - 42
SP - 27
EP - 35
JO - Cell Motility and the Cytoskeleton
JF - Cell Motility and the Cytoskeleton
SN - 1949-3584
IS - 1
ER -