Perturbation of copper (Cu) homeostasis and expression of Cu-binding proteins in cadmium-resistant lung fibroblasts
Perturbation of copper (Cu) homeostasis and expression of Cu-binding proteins in cadmium-resistant lung fibroblasts
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DOI：
10.1093/toxsci/kfm158
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发表时间：
2007-09-01
影响因子：
3.8
通讯作者：
Li, Wande
中科院分区：
文献类型：
--
作者：
Chou, Denise K.;Zhao, Yinzhi;Li, Wande
为探讨镉对肺细胞外基质（ECM）的损伤机制，我们采用不同浓度镉培养法培养了抗镉（CdR）大鼠肺成纤维细胞（RFL 6）。CdR细胞下调赖氨酰氧化酶（LO）（ECM中胶原和弹性蛋白交联所必需的铜u依赖性酶），同时上调其他Cu结合蛋白，包括Cu，Zn-超氧化物歧化酶（SOD 1）、SOD 1的铜伴侣蛋白（CCS 1）、金属硫蛋白（NIT）和门克斯P型ATP酶（ATMA）（高尔基体膜中的Cu转运蛋白），以及γ-谷氨酰半胱氨酸合成酶（γ-GCS），一种谷胱甘肽生物合成酶。减少和损失的细胞质分布的LO在CdR细胞伴随着其错位与门克斯P-型ATP酶和内质网标记。CdR cc Is表现出LO催化活性的缺陷，但Cu，Zn-SOD催化活性的增强与这些酶的蛋白质表达水平一致。虽然长期镉暴露的细胞增强了门克斯P型ATP酶蛋白的表达，实际上，它降低了铜依赖的催化活性的这种酶与LO的不足。低水平的Cu-64结合到LO部分和高水平的64 Cu结合到NIT部分提供了直接的证据，限制铜生物利用度的LO存在于CdR细胞。这些结果表明，下调LO与上调其他铜结合蛋白和改变铜稳态的CdR表型。
To probe mechanisms of cadmium (Cd) damage to the lung extracellular matrix (ECM), we developed Cd-resistant (CdR) rat lung fibroblasts (RFL6) by incubation with graded concentrations of Cd. CdR cells downregulated lysyl oxidase (LO), a copper u dependent enzyme essential for crosslinking of collagen and elastin in the ECM, in conjunction with upregulation of other Cubinding proteins including Cu,Zn-superoxide dismutase (SOD1), copper chaperone for SOD1 (CCS1), metallothionein (NIT), and Menkes P-type ATPase (ATMA), a Cu transporter in the membrane of the Golgi apparatus, as well as gamma-glutamylcysteine synthetase (gamma-GCS), an enzyme for glutathione biosynthesis. Reduction and loss of cytoplasmic distribution of LO in CdR cells were accompanied by its dislocation with the Menkes P-type ATPase and the endoplasmic reticulum marker. CdR cc Is displayed a defect in LO catalytic activity but an enhancement in Cu,Zn-SOD catalytic activity consistent with the protein expression levels of these enzymes. Although long-term Cd exposure of cells enhanced the Menkes P-type ATPase protein expression, actually, it reduced Cu-dependent catalytic activity of this enzyme in parallel with the deficiency of LO. The low level of Cu-64 bound to the LO fraction and the high level of 64Cu bound to the NIT fraction provide direct evidence for limitation of Cu bioavailability for LO existing in the CdR cells. These results suggest that downregulation of LO is linked with upregulation of other Cu-binding proteins and with alteration in Cu homeostasis in the CdR phenotype.