Maitotoxin-induced phosphoinositide hydrolysis is dependent on extracellular but not intracellular Ca2+ in human astrocytoma cells.
Since maitotoxin, a potent marine toxin, is known to cause not only Ca2+ influx but also phosphoinositide hydrolysis, we investigated the Ca2+ dependency of maitotoxin-induced phosphoinositide hydrolysis in 1321N1 human astrocytoma cells. Maitotoxin elicited inositol 1,4,5-trisphosphate accumulation in a time-dependent manner. In [3H]inositol-labeled cells, maitotoxin stimulated phosphoinositide hydrolysis in an extracellular Ca2+-dependent manner. Maitotoxin also caused an intracellular Ca2+ elevation, which was abolished by an intracellular Ca2+ chelater BAPTA-AM. Interestingly, maitotoxin still caused phosphoinositide hydrolysis in the BAPTA-AM-treated cells. These results indicate that maitotoxin-induced phosphoinositide hydrolysis is dependent on extracellular but not intracellular Ca2+ in 1321N1 human astrocytoma cells.
Nakahata
N
N
Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
Yaginuma
T
T
Ohizumi
Y
Y
D001254:Astrocytoma / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007476:Ionophores / Q000494:pharmacology; D008387:Marine Toxins / Q000633:toxicity*; D035964:Oxocins; D010716:Phosphatidylinositols / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D000095702:Polyether Toxins
D000001:Calcimycin; D002118:Calcium; D002614:Chelating Agents; D004533:Egtazic Acid; D015544:Inositol 1,4,5-Trisphosphate; D007476:Ionophores; D008387:Marine Toxins; D035964:Oxocins; D010716:Phosphatidylinositols; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; C020394:maitotoxin; D000095702:Polyether Toxins