title: Crosstalk between Ca2+ signaling and mitochondrial H2O2 is required for rotenone inhibition of mTOR signaling pathway leading to neuronal apoptosis.
abstract: Rotenone, a neurotoxic pesticide, induces loss of dopaminergic neurons related to Parkinson's disease. Previous studies have shown that rotenone induces neuronal apoptosis partly by triggering hydrogen peroxide (H2O2)-dependent suppression of mTOR pathway. However, the underlying mechanism is not fully understood. Here, we show that rotenone elevates intracellular free calcium ion ([Ca2+]i) level, and activates CaMKII, resulting in inhibition of mTOR signaling and induction of neuronal apoptosis. Chelating [Ca2+]i with BAPTA/AM, preventing extracellular Ca2+ influx using EGTA, inhibiting CaMKII with KN93, or silencing CaMKII significantly attenuated rotenone-induced H2O2 production, mTOR inhibition, and cell death. Interestingly, using TTFA, antimycin A, catalase or Mito-TEMPO, we found that rotenone-induced mitochondrial H2O2 also in turn elevated [Ca2+]i level, thereby stimulating CaMKII, leading to inhibition of mTOR pathway and induction of neuronal apoptosis. Expression of wild type mTOR or constitutively active S6K1, or silencing 4E-BP1 strengthened the inhibitory effects of catalase, Mito-TEMPO, BAPTA/AM or EGTA on rotenone-induced [Ca2+]i elevation, CaMKII phosphorylation and neuronal apoptosis. Together, the results indicate that the crosstalk between Ca2+ signaling and mitochondrial H2O2 is required for rotenone inhibition of mTOR-mediated S6K1 and 4E-BP1 pathways. Our findings suggest that how to control over-elevation of intracellular Ca2+ and overproduction of mitochondrial H2O2 may be a new approach to deal with the neurotoxicity of rotenone.
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
authors: Chunxiao
authors: C
authors: Liu
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
authors: Yangjing
authors: Y
authors: Ye
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
authors: Qian
authors: Q
authors: Zhou
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
authors: Ruijie
authors: R
authors: Zhang
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
authors: Hai
authors: H
authors: Zhang
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
authors: Wen
authors: W
authors: Liu
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
authors: Chong
authors: C
authors: Xu
authors: Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
authors: Lei
authors: L
authors: Liu
authors: Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.|Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
authors: Shile
authors: S
authors: Huang
authors: Jiangsu Key Laboratory for Molecular and Medical Biotechnology, Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, PR China.
authors: Long
authors: L
authors: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors; D049109:Cell Proliferation; D002478:Cells, Cultured; D039642:Eukaryotic Initiation Factors / Q000037:antagonists & inhibitors; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D016877:Oxidants / Q000494:pharmacology; D016716:PC12 Cells; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D012402:Rotenone / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D039642:Eukaryotic Initiation Factors; D016877:Oxidants; D014475:Uncoupling Agents; D012402:Rotenone; D006861:Hydrogen Peroxide; D058570:TOR Serine-Threonine Kinases; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D002118:Calcium
keywords: CaMKII; H2O2; Pathology Section; apoptosis; calcium ion; mTOR; rotenone