title: Coordinative modulation of human zinc transporter 2 gene expression through active and suppressive regulators.
abstract: Zinc transporter 2 (ZnT2) is one of the cellular factors responsible for Zn homeostasis. Upon Zn overload, ZnT2 reduces cellular Zn by transporting it into excretory vesicles. We investigated the molecular mechanism that regulates human ZnT2 (hZnT2) gene expression. Zn induces hZnT2 expression in dose- and time-dependent manners. Overexpression of metal-responsive transcription factor 1 (MTF-1) increases hZnT2 transcription, whereas depletion of MTF-1 reduces hZnT2 expression. There are five putative metal response elements (MREs) within 1kb upstream of the hZnT2 gene. A serial deletion of the hZnT2 promoter region (from 5' to 3') shows that the two MREs proximal to the gene are essential for Zn-induced promoter activity. Further mutation analysis concludes that the penultimate MRE (MREb) supports the metal-induced promoter activity. The hZnT2 promoter has also a zinc finger E-box binding homeobox (ZEB) binding element. Mutation or deletion of this ZEB binding element elevates the basal and Zn-induced hZnT2 promoter activities. Knockdown of ZEB1 mRNA enhances the hZnT2 transcript level in HEK-293 cells. In MCF-7 (ZEB-deficient) cells, expression of ZEB proteins attenuates the Zn-induced hZnT2 expression. However, expressions of MTF-1 target genes such as human ZnT1 and metallothionein IIA were not affected. Our study shows the expression of the hZnT2 gene is coordinately regulated via active and suppressive modulators.
authors.affiliation: Institute of Molecular and Cellular Biology and Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Yu-Ju
authors.initials: YJ
authors.lastname: Lu
authors.affiliation: Institute of Molecular and Cellular Biology and Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Ya-Chuan
authors.initials: YC
authors.lastname: Liu
authors.affiliation: Institute of Molecular and Cellular Biology and Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Meng-Chieh
authors.initials: MC
authors.lastname: Lin
authors.affiliation: Institute of Molecular and Cellular Biology and Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Chen
authors.affiliation: Institute of Molecular and Cellular Biology and Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan. Electronic address: lylin@life.nthu.edu.tw.
authors.forename: Lih-Yuan
authors.initials: LY
authors.lastname: Lin
mesh_terms: D000818:Animals; D016466:CHO Cells; D002104:Cadmium / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D003412:Cricetulus; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D057809:HEK293 Cells; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D061986:MCF-7 Cells; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection; D015032:Zinc / Q000378:metabolism; D000071799:Zinc Finger E-box-Binding Homeobox 1; D000097809:Transcription Factor MTF-1
chemical_list: D002104:Cadmium; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D008668:Metallothionein; D012333:RNA, Messenger; D014157:Transcription Factors; D015032:Zinc; D000071799:Zinc Finger E-box-Binding Homeobox 1; D000097809:Transcription Factor MTF-1; C486299:SLC30A2 protein, human; C486307:ZEB1 protein, human
keywords: Metal response element; Metal-responsive transcription factor 1; Zinc; Zinc finger E-box-binding homeobox; Zinc transporter 2