Premium
Ca 2+ store depletion and endoplasmic reticulum stress are involved in P2X7 receptor‐mediated neurotoxicity in differentiated NG108‐15 cells
Author(s) -
Chao ChiaChia,
Huang ChiehChen,
Lu DahYuu,
Wong KarLok,
Chen YunRu,
Cheng TzuHurng,
Leung YukMan
Publication year - 2012
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.24010
Subject(s) - endoplasmic reticulum , programmed cell death , extracellular , unfolded protein response , cyclopiazonic acid , cytosol , apoptosis , receptor , chemistry , fura 2 , microbiology and biotechnology , inositol , biology , biochemistry , enzyme
P2X7 receptor (P2X7R) activation by extracellular ATP triggers influx of Na + and Ca 2+ , cytosolic Ca 2+ overload and consequently cytotoxicity. Whether disturbances in endoplasmic reticulum (ER) Ca 2+ homeostasis and ER stress are involved in P2X7R‐mediated cell death is unknown. In this study, a P2X7R agonist (BzATP) was used to activate P2X7R in differentiated NG108‐15 neuronal cells. In a concentration‐dependent manner, application of BzATP (10–100 µM) immediately raised cytosolic Ca 2+ concentration ([Ca 2+ ] i ) and caused cell death after a 24‐h incubation. P2X7R activation for 2 h did not cause cell death but resulted in a sustained reduction in ER Ca 2+ pool size, as evidenced by a diminished cyclopiazonic acid‐induced Ca 2+ discharge (fura 2 assay) and a lower fluorescent signal in cells loaded with Mag‐fura 2 (ER‐specific Ca 2+ ‐fluorescent dye). Furthermore, P2X7R activation (2 h) led to the appearance of markers of ER stress [phosphorylated α subunit of eukaryotic initiation factor 2 (p‐eIF2α) and C/EBP homologous protein (CHOP)] and apoptosis (cleaved caspase 3). Xestospongin C (XeC), an antagonist of inositol‐1,4,5‐trisphosphate (IP 3 ) receptor (IP3R), strongly inhibited BzATP‐triggered [Ca 2+ ] i elevation, suggesting that the latter involved Ca 2+ release via IP3R. XeC pretreatment not only attenuated the reduction in Ca 2+ pool size in BzATP‐treated cells, but also rescued cell death and prevented BzATP‐induced appearance of ER stress and apoptotic markers. These novel observations suggest that P2X7R activation caused not only Ca 2+ overload, but also Ca 2+ release via IP3R, sustained Ca 2+ store depletion, ER stress and eventually apoptotic cell death. J. Cell. Biochem. 113: 1377–1385, 2012. © 2011 Wiley Periodicals, Inc.