title: Defective roles of ATP7B missense mutations in cellular copper tolerance and copper excretion.
abstract: Wilson's disease (WD) is a hereditary disorder of copper metabolism resulting from mutations within ATP7B. Clinical investigations showed that ATP7B missense mutations cause a wide variety of symptoms in WD patients, which implies that those mutations might affect ATP7B function in a number of ways and each would have deleterious consequences on normal copper distribution and lead to WD. Nonetheless, it is still unknown about the influences of those mutations on ATP7B function of increasing copper excretion and enhancing cellular copper tolerance. Here we established the stable expression cell lines of wild-type (WT) ATP7B and its four missense mutants (R778L, R919G, T935M and P992L), tested cellular copper tolerance and copper excretion using those cell lines, and also observed cellular distribution of WT ATP7B proteins and those mutants in transiently transfected cells. We found that extrinsic expressing WT ATP7B reduced CuCl2-induced copper accumulation and enhanced cellular copper tolerance by accelerating copper excretion, which was selectively compromised by R778L and P992L mutations. Further investigation showed that R778L mutation disrupted the subcellular localization and trafficking of ATP7B proteins, whereas P992L mutation only affected the trafficking of ATP7B. This indicates that ATP7B missense mutants have distinct effects on cellular copper tolerance.
authors.affiliation: Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and the Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, China; Department of Neurology and Institute of Neurology, Huashan Hospital, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Department of Neurology and Institute of Neurology, Huashan Hospital, Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and the Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Ni
authors.affiliation: Department of Neurology and Research Center of Neurology in Second Affiliated Hospital, and the Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, China. Electronic address: zhiyingwu@zju.edu.cn.
authors.forename: Zhi-Ying
authors.initials: ZY
authors.lastname: Wu
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism; D003300:Copper / Q000378:metabolism* / Q000633:toxicity; D000073840:Copper-Transporting ATPases; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D017136:Ion Transport; D020125:Mutation, Missense
chemical_list: D027682:Cation Transport Proteins; D003300:Copper; D000251:Adenosine Triphosphatases; C000612464:ATP7B protein, human; D000073840:Copper-Transporting ATPases
keywords: ATP7B; Cellular copper tolerance; Copper excretion; Missense mutation; Wilson's disease