Activation of stress response by ionomycin in rat hepatoma cells.
All living systems respond to a variety of stress conditions by inducing the synthesis of stress or heat shock proteins (HSPs), which transiently protect cells. HSP synthesis was preceded by an increase in intracellular free calcium concentration [(Ca(2+))i]. In this study, we show that Ca(2+) ionophore, ionomycin, induced an immediate increase in intracellular free Ca(2+) and examined how this increase affects heat shock response in rat hepatoma cell line H4II-E-C3. Results indicate that incubating H4II-E-C3 cells with 0.3 microM ionomycin at 37 degrees C for 15 min results in the induction of HSP 70 in both Ca(2+)-containing and Ca(2+)-free medium. Associated with this increase in free Ca(2+) is an in vivo change in membrane organization and activation of signaling molecules like ERKS and SAPKs/JNK. In Ca(2+) containing medium HSP 70 induction mediated by HSF-HSE interaction was faster upon ionomycin treatment as compared to heat shock. Our results show that ionomycin, at sub lethal concentration, increases intracellular free Ca(2+) concentration, activates SAPK/JNK and HSF-HSE interaction, and induces HSP 70 synthesis.
Sreedhar
A S
AS
Centre for Cellular and Molecular Biology, Hyderabad 500 007, India.
Srinivas
Usha K
UK
D000818:Animals; D002118:Calcium / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000201:enzymology / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000187:drug effects; D015759:Ionomycin / Q000494:pharmacology*; D048031:JNK Mitogen-Activated Protein Kinases; D048056:Mitogen-Activated Protein Kinase 9; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D051381:Rats; D013312:Stress, Physiological / Q000139:chemically induced* / Q000201:enzymology / Q000378:metabolism*; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; D014157:Transcription Factors; D015759:Ionomycin; D048056:Mitogen-Activated Protein Kinase 9; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium