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PLoS One. 2011 Apr 22;6(4):e19052. doi: 10.1371/journal.pone.0019052.

Calcium signaling is involved in cadmium-induced neuronal apoptosis via induction of reactive oxygen species and activation of MAPK/mTOR network.

Author information

1
Department of Biochemistry and Molecular Biology, Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, Louisiana, United States of America.

Abstract

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 ([Ca²+](i)) level in PC12, SH-SY5Y cells and primary murine neurons. BAPTA/AM, an intracellular Ca²+ chelator, abolished Cd-induced [Ca²+](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 Ca²+ chelator EGTA also prevented Cd-induced [Ca²+](i) elevation, MAPK/mTOR activation, as well as cell death, suggesting that Cd-induced extracellular Ca²+ 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 [Ca²+](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 [Ca²+](i), which induces ROS and activates MAPK and mTOR pathways, leading to neuronal apoptosis. The results suggest that regulation of Cd-disrupted [Ca²+](i) homeostasis may be a new strategy for prevention of Cd-induced neurodegenerative diseases.

PMID:
21544200
PMCID:
PMC3081326
DOI:
10.1371/journal.pone.0019052
[Indexed for MEDLINE]
Free PMC Article

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