Involvement of chloride channels in hepatic copper metabolism: ClC-4 promotes copper incorporation into ceruloplasmin.
Involvement of chloride channels in hepatic copper metabolism: ClC-4 promotes copper incorporation into ceruloplasmin.
复制标题
氯离子通道参与肝铜代谢：ClC-4 促进铜掺入铜蓝蛋白。
DOI：
10.1053/j.gastro.2004.01.015
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发表时间：
2004
期刊：
影响因子：
29.4
通讯作者：
Weinman,StevenA
中科院分区：
文献类型：
--
作者：
Wang,Ting;Weinman,StevenA
背景与目的肝细胞铜转运受多个泵、分子伴侣和辅助蛋白相互作用的调控。胞内氯离子通道是酵母细胞铜代谢的重要通道，但其在肝细胞铜转运中的作用尚不清楚。本研究的目的是确定氯通道是否是铜掺入铜蓝蛋白（CP）的调节剂。方法通过凝胶电泳和免疫印迹法测定氯浓度和氯通道表达对holoCp和apoCp分泌的影响。通过Western印迹法测定肝细胞中ClC家族氯通道的表达。ClC-4和威尔逊氏病蛋白（ATP 7 B）的协会被确定由co-immunoprecipitation. ResultsCl取代减少总Cp分泌和分泌的holoCp的apoCp的比例（P = 0.038）。通过铜蓝蛋白和氯离子通道的共转染研究了特定氯离子通道的作用。C1 C-4的过表达使铜蓝蛋白中铜的掺入增加一倍（P = 0.011），而C1 C-3的相同过表达没有影响。在铜限制条件下，ClC-4的作用最明显，其中它使铜掺入增加超过4倍（P = 0.037）。结论ClC-4是一种细胞内氯离子通道，通过提高ATP 7 B铜泵的效率，促进铜离子进入铜蓝蛋白。因此，它是调节肝脏铜转运的重要组成部分，并可能在铜缺乏、威尔逊病和其他铜中毒综合征期间调节铜转运速率。
Background & AimsCopper transport in hepatocytes is regulated by the interaction of multiple pumps, chaperones, and accessory proteins. Intracellular chloride channels are essential for copper metabolism in yeast but their role in Cu transport in hepatocytes is unknown. The aim of this study was to determine whether chloride channels are modulators of copper incorporation into ceruloplasmin (CP).MethodsThe effects of chloride concentration and chloride channel expression on secretion of holoCp and apoCp was measured by gel electrophoresis and immunoblotting. ClC family chloride channel expression in hepatocytes was determined by Western blotting. The association of ClC-4 and the Wilson’s disease protein (ATP7B) was determined by co-immunoprecipitation.ResultsChloride substitution reduced total Cp secretion and the ratio of secreted holoCp to apoCp (P = 0.038). The role of specific chloride channels was examined by cotransfection of ceruloplasmin and the chloride channel. Overexpression of ClC-4 doubled copper incorporation into ceruloplasmin (P = 0.011), whereas identical overexpression of ClC-3 had no effect. The effect of ClC-4 was most pronounced under copper-limiting conditions in which it increased copper incorporation more than 4-fold (P = 0.037). ClC-4 protein was abundant in hepatocyte membranes and was localized in intracellular vesicles containing ATP7B.ConclusionsClC-4 is an intracellular chloride channel that stimulates copper incorporation into ceruloplasmin, probably by improving the efficiency of the ATP7B copper pump. It is thus an important component of the regulation of hepatic copper transport and may modulate Cu transport rates during copper deficiency, Wilson’s disease, and other copper toxicosis syndromes.