Mechanisms for biological control of metals and participation of metal-binding proteins : disordered copper metabolism in LEC rats.

我们的方法可以在以下几个小标题下描述：(I)导致和紧随急性肝炎的LEC大鼠的铜的正常积累过程，(Ii)LEC大鼠的铜从金属硫蛋白选择性地转移到铜结合酶中，(Iii)通过四硫钼酸盐选择性地去除与金属硫蛋白结合的铜并从急性肝炎中恢复，以及(Iv)增强诱导LEC大鼠肝脏中金属硫蛋白的合成。我们的实验表明，LEC大鼠的肝脏中铜以与金属硫蛋白结合的形式积累，达到肝脏合成该蛋白质的能力极限。然后，未与金属硫蛋白结合的铜开始以游离形式出现在肝细胞中，急性肝炎(黄疸)的迹象开始出现。从肝脏中的铜金属硫蛋白中释放出来的铜在血液中被检测到，并被肾脏隔离。虽然铜蓝蛋白(一种特定的铜依赖蛋白)不结合铜，而脱铜蛋白在LEC大鼠的血清中出现，但铜锌超氧化物歧化酶可以利用铜锌超氧化物歧化酶。这一现象可以通过铜从金属硫蛋白直接和选择性地转移到脱脂超氧化物歧化酶来解释。用四硫代钼酸盐选择性地去除肝脏中与金属硫蛋白结合的铜，并提出了钼-铜-硫络合物的形成机理。用四硫代钼酸盐治疗可以治愈LEC大鼠的急性肝炎。LEC大鼠铜的异常蓄积现在解释为缺乏铜结合的肝脏ATPase，导致铜从这个器官外流。然而，我们的结果表明，即使在LEC大鼠的肝细胞中，在去除铜并将金属硫蛋白mRNA水平降低到正常值后，金属硫蛋白的合成也被增强，这表明铜选择性地在LEC大鼠肝细胞中过表达金属硫蛋白。

Our approach can be described under several subheadings as following : (i) Process of normal accumulation of copper in LEC rats leading to and following acute hepatitis, (ii) Selective transfer of copper from metallothionein to copper-binding enzymes in LEC rats, (iii) Selective removal of copper bound to metallothionein by tetrathiomolybdate and recovery from acute hepatitis, and (iv) Enhanced induction of metallothionein synthesis in the liver of LEC rats.Our experiments revealed that copper accumulates in the liver of LEC rats in a form bound to metallothionein up to the limits of liver's capacity to synthesize this protein. Then copper not bound to metallothionein starts to appear in free form in liver cells and signs of acute hepatitis (jaundice) begin to appear. Copper liberated from the copper-metallothionein in liver is detected in the blood stream and is sequestered by the kidney. Although, this copper is not incorporated in ceruloplasmin (a specific copper-dependent protein) and apo-ceruloplasmin appears in the serum of LEC rats, the metal can be utilized by the copper, zinc-superoxide dismutase. The phenomenon can be explained by a direct and selective transfer of copper from metallothionein to apo-superoxide dismutase. Copper present in liver, bound to metallothionein was removed selectively by tetrathiomolybdate and the mechanisms, including the formation of molybdenum-copper-sulfur complexes, were proposed. LEC rats can be cured from the acute hepatitis by treatment with tetrathiomolybdate.Abnormal accumulation of copper in LEC rats is now explained by the lack of copper-binding liver ATPase, which cause the efflux of copper from this organ, However, our results suggest that metallothionein synthesis is enhanced even in the hepatocytes derived from the LEC rats after removing copper and lowering the metallothionein mRNA levels to normal values, indicating that metallothionein is overexpressed in LEC rats selectively by copper.