title: The protective role of Nrf2-Gadd45b against antimony-induced oxidative stress and apoptosis in HEK293 cells.
abstract: Antimony (Sb) is one of the most prevalent heavy metals and frequently causes biological toxicity. However, the specific mechanisms by which Sb elicits its toxic effects remains to be fully elucidated. In this study, we found antimony trioxide (Sb2O3) caused a dose-dependent cytotoxicity against HEK293 cells, and Sb2O3-induced excessive reactive oxygen species (ROS) was closely correlated with increased cell apoptosis. Mechanistic investigation manifested that nuclear factor NF-E2-related factor 2 (Nrf2) expression and nuclear translocation were significantly induced under Sb2O3 treatment in HEK293 cells, and Nrf2 knockdown aggregated Sb2O3-induced cell apoptosis. Moreover, elevated Gadd45b expression actives the phosphorylation of MAPKs upon Sb2O3 exposure, whereas Gadd45b knockdown diminished Sb2O3-induced activation of MAPKs and promoted cell apoptosis. In the meantime, however, the antioxidant N-acetylcysteine (NAC) was found to ameliorate Nrf2 expression and nuclear translocation as well as Gadd45b expression and MAPKs activation by repressing Sb2O3-induced ROS production. More importantly, we found Gadd45b was transcriptionally enhanced by Nrf2 through binding to three canonical antioxidant response elements (AREs) within its promoter region. Either Sb2O3 or TBHQ (a selective Nrf2 activator) treatment, Gadd45b expression was significantly increased by luciferase assay. Nrf2 inhibition greatly diminished Gadd45b expression due to reduced binding of Nrf2 in Gadd45b promoter under Sb2O3 treatment. To summarize, this study demonstrated the Nrf2-Gadd45b signaling axis exhibited a protective role in Sb-induced cell apoptosis.
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China.
authors.forename: Xingkang
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China.
authors.forename: Zesheng
authors.initials: Z
authors.lastname: An
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Lu
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China.
authors.forename: E
authors.initials: E
authors.lastname: Du
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China.
authors.forename: Shiyong
authors.initials: S
authors.lastname: Qi
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China.
authors.forename: Kuo
authors.initials: K
authors.lastname: Yang
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China. Electronic address: drzhangzhihong@163.com.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Urology, The Second Hospital of Tianjin Medical University, Tianjin Institute of Urology, Tianjin 300211, China. Electronic address: yongxu2012@yahoo.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism*; D000965:Antimony / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D001665:Binding Sites; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D000097642:GADD45 Proteins
chemical_list: D000943:Antigens, Differentiation; D000965:Antimony; D020928:Mitogen-Activated Protein Kinases; D051267:NF-E2-Related Factor 2; D017382:Reactive Oxygen Species; C086470:GADD45B protein, human; D000097642:GADD45 Proteins; C495635:NFE2L2 protein, human; C037554:antimony trioxide
keywords: Antimony; Apoptosis; Gadd45b; Nrf2; ROS