title: Heavy metal-induced metallothionein expression is regulated by specific protein phosphatase 2A complexes.
abstract: Induction of metallothionein (MT) expression is involved in metal homeostasis and detoxification. To identify the key pathways that regulate metal-induced cytotoxicity, we investigate how phosphorylated metal-responsive transcription factor-1 (MTF-1) contributed to induction of MT expression. Immortal human embryonic kidney cells (HEK cells) were treated with seven kinds of metals including cadmium chloride (CdCl2), zinc sulfate (ZnSO4), copper sulfate(CuSO4), lead acetate (PbAc), nickel sulfate (NiSO4), sodium arsenite (NaAsO2), and potassium bichromate (K2Cr2O7). The MT expression was induced in a dose-response and time-dependent manner upon various metal treatments. A cycle of phosphorylation and dephosphorylation was required for translocation of MTF-1 from cytoplasm to nucleus, leading to the up-regulation of MTs expression. Protein phosphatase 2A (PP2A) participated in regulating MT expression through dephosphorylation of MTF-1. A loss-of-function screen revealed that the specific PP2A complexes containing PR110 were involved in metal-induced MT expression. Suppression of PP2A PR110 in HEK cells resulted in the persistent MTF-1 phosphorylation and the disturbance of MTF-1 nuclear translocation, which was concomitant with a significant decrease of MT expression and enhanced cytotoxicity in HEK cells. Notably, MTF-1 was found in complex with specific PP2A complexes containing the PR110 subunit upon metal exposure. Furthermore, we identify that the dephosphorylation of MTF-1 at residue Thr-254 is directly regulated by PP2A PR110 complexes and responsible for MTF-1 activation. Taken together, these findings delineate a novel pathway that determines cytotoxicity in response to metal treatments and provide new insight into the role of PP2A in cellular stress response.
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Liping
authors: L
authors: Chen
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Lu
authors: L
authors: Ma
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Qing
authors: Q
authors: Bai
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Xiaonian
authors: X
authors: Zhu
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Jinmiao
authors: J
authors: Zhang
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Qing
authors: Q
authors: Wei
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Daochuan
authors: D
authors: Li
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Chen
authors: C
authors: Gao
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Jie
authors: J
authors: Li
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Zhengbao
authors: Z
authors: Zhang
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Caixia
authors: C
authors: Liu
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Zhini
authors: Z
authors: He
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
authors: Xiaowen
authors: X
authors: Zeng
authors: Department of Toxicology, School of Public Health, Guiyang Medical University, Guiyang 550004, China.
authors: Aihua
authors: A
authors: Zhang
authors: Department of Environmental Health, School of Public Health, Fudan University, Shanghai 200032, China, and.
authors: Weidong
authors: W
authors: Qu
authors: Department of Toxicology, Shenzhen Center for Disease Control and Prevention, Shenzhen 518001, China.
authors: Zhixiong
authors: Z
authors: Zhuang
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China, chenwen@mail.sysu.edu.cn.
authors: Wen
authors: W
authors: Chen
authors: From the Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China, xiaoym@mail.sysu.edu.cn.
authors: Yongmei
authors: Y
authors: Xiao
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D019943:Amino Acid Substitution; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D008668:Metallothionein / Q000096:biosynthesis* / Q000235:genetics*; D019216:Metals, Heavy / Q000633:toxicity*; D009097:Multienzyme Complexes / Q000737:chemistry / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000737:chemistry / Q000378:metabolism*; D021122:Protein Subunits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological; D013912:Threonine / Q000737:chemistry; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000097809:Transcription Factor MTF-1
chemical_list: D004268:DNA-Binding Proteins; D008668:Metallothionein; D019216:Metals, Heavy; D009097:Multienzyme Complexes; D054648:Protein Phosphatase 2; D021122:Protein Subunits; D011994:Recombinant Proteins; D013912:Threonine; D014157:Transcription Factors; D000097809:Transcription Factor MTF-1
keywords: Cell Biology; Cytotoxicity; Metal-responsive Transcription Factor-1; Metallothione; Metallothioneins; Protein Phosphatase 2 (PP2A); Protein Phosphatase 2A; Stress Response; Transcription Factor