title: Melatonin antagonizes cadmium-induced neurotoxicity by activating the transcription factor EB-dependent autophagy-lysosome machinery in mouse neuroblastoma cells.
abstract: Cadmium (Cd), a highly ubiquitous heavy metal, induces neurotoxicity. Melatonin, a major secretory product of the pineal gland, protects against Cd-induced neurotoxicity. However, the mechanism that accounts for this protection remains to be elucidated. Herein, we exposed mouse neuroblastoma cells (Neuro-2a cells) to different concentrations of cadmium chloride (CdCl2 ) (12.5, 25, and 50 μ mol L(-1) ) for 24 hours. We showed that Cd inhibits autophagosome-lysosome fusion and impairs lysosomal function, subsequently leading to nerve cell death. In addition, Cd decreases the level of transcription factor EB (TFEB) but induces the nuclear translocation of TFEB, associated with compromised lysosomal function or a compensatory effect after the impairment of the autophagic flux. Moreover, compared to the 50-μ mol L(-1) Cd group, administration of 1 μ mol L(-1) melatonin increased "TFEB-responsive genes" (P<.05) and the levels of lysosomal-associated membrane protein (0.57±0.06 vs 1.00±0.11, P<.05), preserved lysosomal protease activity (0.52±0.01 vs 0.90±0.02, P<.05), maintained the lysosomal pH level (0.50±0.01 vs 0.87±0.05, P<.01), and enhanced autophagosome-lysosome fusion (0.05±0.00 vs 0.21±0.01, P<.01). Notably, melatonin enhanced TFEB expression (0.37±0.04 vs 0.72±0.07, P<.05) and nuclear translocation (2.81±0.08 vs 3.82±0.05, P<.05). Tfeb siRNA blocked the melatonin-mediated elevation in autophagy-lysosome machinery in Cd-induced neurotoxicity (P<.01). Taken together, these results uncover a potent role for TFEB-mediated autophagy in the pathogenesis of Cd-induced neurotoxicity, suggesting that control of the autophagic pathway by melatonin might provide an important clue for exploring potential targets for novel therapeutics of Cd-induced neurotoxicity.
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Huifeng
authors.initials: H
authors.lastname: Pi
authors.affiliation: Brain Research Center, Third Military Medical University, Chongqing, China.|Department of Neurology, Army General Hospital in Lanzhou, Lanzhou, China.
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Department of Cellular and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Russel J
authors.initials: RJ
authors.lastname: Reiter
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Shangcheng
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Neurology, Army General Hospital in Lanzhou, Lanzhou, China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.|Department of Molecular Biology, University of Texas Southwestern Medical Center, San Antonio, TX, USA.
authors.forename: Chunhai
authors.initials: C
authors.lastname: Chen
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Yang
authors.affiliation: Institute of Hepatobiliary Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing, China.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.|Department of Neurology, Wuhan General Hospital, Wuhan, China.
authors.forename: Pan
authors.initials: P
authors.lastname: Guo
authors.affiliation: Department of Health Statistics, Third Military Medical University, Chongqing, China.
authors.forename: Gaoming
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Manyu
authors.initials: M
authors.lastname: Tu
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Tian
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Xie
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Mindi
authors.initials: M
authors.lastname: He
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhong
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China.
authors.forename: Yanwen
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China. yuzping_tmmu@126.com.
authors.forename: Zhengping
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Department of Occupational Health, Third Military Medical University, Chongqing, China. lunazhou00@163.com.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism*; D002104:Cadmium / Q000633:toxicity; D019256:Cadmium Chloride / Q000633:toxicity*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism* / Q000473:pathology; D008247:Lysosomes / Q000378:metabolism*; D008550:Melatonin / Q000494:pharmacology*; D051379:Mice; D009363:Neoplasm Proteins / Q000378:metabolism*; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D020258:Neurotoxicity Syndromes / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D009363:Neoplasm Proteins; C484068:Tcfeb protein, mouse; D002104:Cadmium; D019256:Cadmium Chloride; D008550:Melatonin
keywords: autophagy; cadmium; lysosomal function; melatonin; neurotoxicity; transcription factor EB