Open AccessCalcium Signaling Is Involved in Cadmium-Induced Neuronal Apoptosis via Induction of Reactive Oxygen Species and Activation of MAPK/mTOR Network
Author(s) -
Baoshan Xu,
Sujuan Chen,
Yan Luo,
Zi Chen,
Lei Liu,
Hongyu Zhou,
Wenxing Chen,
Tao Shen,
Xiuzhen Han,
Long Chen,
Shile Huang
Publication year - 2011
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0019052
Subject(s) - reactive oxygen species , calcium , cadmium , apoptosis , microbiology and biotechnology , pi3k/akt/mtor pathway , mapk/erk pathway , calcium signaling , chemistry , signal transduction , biology , biochemistry , organic chemistry
Cadmium (Cd), a toxic environmental contaminant, induces oxidative stress, leading to neurodegenerative disorders. Recently we have demonstrated that Cd induces neuronal apoptosis in part by activation of the mitogen-activated protein kineses (MAPK) and mammalian target of rapamycin (mTOR) pathways. However, the underlying mechanism remains elusive. Here we show that Cd elevated intracellular calcium ion ([Ca 2+ ] i ) level in PC12, SH-SY5Y cells and primary murine neurons. BAPTA/AM, an intracellular Ca 2+ chelator, abolished Cd-induced [Ca 2+ ] i elevation, and blocked Cd activation of MAKPs including extracellular signal-regulated kinase 1/2 (Erk1/2), c-Jun N-terminal kinase (JNK) and p38, and mTOR-mediated signaling pathways, as well as cell death. Pretreatment with the extracellular Ca 2+ chelator EGTA also prevented Cd-induced [Ca 2+ ] i elevation, MAPK/mTOR activation, as well as cell death, suggesting that Cd-induced extracellular Ca 2+ influx plays a critical role in contributing to neuronal apoptosis. In addition, calmodulin (CaM) antagonist trifluoperazine (TFP) or silencing CaM attenuated the effects of Cd on MAPK/mTOR activation and cell death. Furthermore, Cd-induced [Ca 2+ ] i elevation or CaM activation resulted in induction of reactive oxygen species (ROS). Pretreatment with BAPTA/AM, EGTA or TFP attenuated Cd-induced ROS and cleavage of caspase-3 in the neuronal cells. Our findings indicate that Cd elevates [Ca 2+ ] i , which induces ROS and activates MAPK and mTOR pathways, leading to neuronal apoptosis. The results suggest that regulation of Cd-disrupted [Ca 2+ ] i homeostasis may be a new strategy for prevention of Cd-induced neurodegenerative diseases.