Depletion of intracellular Ca2+ store itself may be a major factor in thapsigargin-induced ER stress and apoptosis in PC12 cells.
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)).
Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka 812-8582, Japan.
Ichiro
I
Yoshida
Akira
A
Monji
Ken-ichiro
K
Tashiro
Kei-ichiro
K
Nakamura
Ryuji
R
Inoue
Shigenobu
S
Kanba
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002614:Chelating Agents / Q000494:pharmacology; D003620:Dantrolene / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016257:Fura-2 / Q000031:analogs & derivatives; D006360:Heat-Shock Proteins / Q000187:drug effects / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D007811:Lanthanum / Q000494:pharmacology; D018832:Molecular Chaperones / Q000187:drug effects / Q000378:metabolism; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D009410:Nerve Degeneration / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D016716:PC12 Cells; D051381:Rats; D013312:Stress, Physiological / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D019284:Thapsigargin / Q000494:pharmacology; D000091342:Endoplasmic Reticulum Chaperone BiP
D002118:Calcium; D002614:Chelating Agents; D003620:Dantrolene; D004791:Enzyme Inhibitors; D016257:Fura-2; D006360:Heat-Shock Proteins; D007811:Lanthanum; D018832:Molecular Chaperones; D009125:Muscle Relaxants, Central; D019284:Thapsigargin; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP; C098106:fura-PE3