Copper modulates the degradation of copper chaperone for Cu,Zn superoxide dismutase by the 26 S proteosome
Copper modulates the degradation of copper chaperone for Cu,Zn superoxide dismutase by the 26 S proteosome
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DOI：
10.1074/jbc.m302242200
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发表时间：
2003-09-12
影响因子：
4.8
通讯作者：
L'Abbé, MR
中科院分区：
文献类型：
--
作者：
Bertinato, J;L'Abbé, MR
铜伴侣是一种铜结合蛋白，可以直接将铜插入特定的靶点，防止可能对细胞有毒的游离铜离子的积累。尽管人们对铜从铜伴侣蛋白转移到靶蛋白的认识有了长足的进步，但到目前为止，还没有关于这些蛋白的活性在高等真核生物中如何调节的信息。铜在抗氧化酶铜锌超氧化物歧化酶(SOD1)中的插入依赖于铜超氧化物歧化酶(CCS)的铜伴侣。我们最近报道，在饲喂铜缺乏饲料的大鼠组织中，CCS蛋白表达增加，提示铜可能调节CCS的表达。在这里，我们表明，虽然铜缺乏增加了大鼠CCS蛋白，但mRNA水平没有受到影响。在特定铜络合剂2，3，2-四胺存在下培养的啮齿动物和人类细胞系显示出CCS蛋白的剂量依赖性增加，这种增加可以被细胞中加入铜而不是铁或锌逆转。将细胞从缺乏铜的培养基转到富铜的培养基能促进CCS的快速降解，蛋白酶体抑制剂MG132和lactacystin可以阻止CCS的降解，但半胱氨酸蛋白酶抑制剂和溶酶体降解途径的抑制剂不能阻止CCS的快速降解。此外，缺铜细胞的CCS降解速度慢于富铜培养细胞。综上所述，这些数据表明，铜通过调节26 S蛋白小体的降解来调节CCS的表达，并暗示了CCS在铜缺乏时优先利用铜的新作用。
Copper chaperones are copper-binding proteins that directly insert copper into specific targets, preventing the accumulation of free copper ions that can be toxic to the cell. Despite considerable advances in the understanding of copper transfer from copper chaperones to their target, to date, there is no information regarding how the activity of these proteins is regulated in higher eukaryotes. The insertion of copper into the antioxidant enzyme Cu,Zn superoxide dismutase (SOD1) depends on the copper chaperone for SOD1 (CCS). We have recently reported that CCS protein is increased in tissues of rats fed copper-deficient diets suggesting that copper may regulate CCS expression. Here we show that whereas copper deficiency increased CCS protein in rats, mRNA level was unaffected. Rodent and human cell lines cultured in the presence of the specific copper chelator 2,3,2-tetraamine displayed a dose-dependent increase in CCS protein that could be reversed with the addition of copper but not iron or zinc to the cells. Switching cells from copper-deficient to copper-rich medium promoted the rapid degradation of CCS, which could be blocked by the proteosome inhibitors MG132 and lactacystin but not a cysteine protease inhibitor or inhibitors of the lysosomal degradation pathway. In addition, CCS degradation was slower in copper-deficient cells than in cells cultured in copper-rich medium. Together, these data show that copper regulates CCS expression by modulating its degradation by the 26 S proteosome and suggest a novel role for CCS in prioritizing the utilization of copper when it is scarce.