Abstract
The mechanisms of intracellular calcium store depletion and store-related Ca(2+) dysregulation in relation to apoptotic cell death in PC12 cells were investigated at physiological temperatures with a leak-resistant fluorescent indicator dye Fura-PE3/AM by a cooled CCD imaging analysis system. Electron microscopic observations have shown thapsigargin (TG; 100 nM)-induced apoptosis in PC12 cells. Thorough starvation of stored Ca(2+) by BAPTA/AM (50 microM), or La(3+) (100 microM) enhanced while dantrolene (100 microM) attenuated the TG-induced apoptosis by preventing a calcium release from internal stores. An immunoblotting analysis revealed an enhanced expression of GRP78, the hallmark of endoplasmic reticulum (ER) stress when cells were treated by TG along with BAPTA/AM. These results indicate that the depletion of the intracellular Ca(2+) stores itself induces the ER stress and apoptosis in PC12 cells without any involvement of the capacitative calcium entry (CCE) or a sustained elevation of intracellular Ca(2+) concentrations ([Ca(2+)](i)).
MeSH terms
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Animals
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Apoptosis / drug effects
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Apoptosis / physiology*
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Calcium / metabolism*
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Calcium Signaling / drug effects*
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Calcium Signaling / physiology
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Chelating Agents / pharmacology
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Dantrolene / pharmacology
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Endoplasmic Reticulum / drug effects
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Endoplasmic Reticulum / metabolism*
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Enzyme Inhibitors / pharmacology
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Fura-2 / analogs & derivatives
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Heat-Shock Proteins / drug effects
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Heat-Shock Proteins / metabolism
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Homeostasis / drug effects
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Homeostasis / physiology
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Intracellular Fluid / drug effects
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Intracellular Fluid / metabolism
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Lanthanum / pharmacology
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Molecular Chaperones / drug effects
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Molecular Chaperones / metabolism
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Muscle Relaxants, Central / pharmacology
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Nerve Degeneration / metabolism
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Nerve Degeneration / physiopathology
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Neurons / drug effects
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Neurons / metabolism*
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PC12 Cells
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Rats
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Stress, Physiological / chemically induced
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Stress, Physiological / metabolism*
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Stress, Physiological / physiopathology
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Thapsigargin / pharmacology
Substances
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Chelating Agents
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Enzyme Inhibitors
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GRP78 protein, rat
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Heat-Shock Proteins
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Molecular Chaperones
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Muscle Relaxants, Central
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fura-PE3
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Thapsigargin
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Lanthanum
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Dantrolene
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Calcium
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Fura-2