Hidalgo H A, Koppa V, Bryan S E
Biochem J. 1978 Feb 15;170(2):219-225. doi: 10.1042/bj1700219.
The uptake of cadmium by isolated liver cells was linearly related to the cadmium concentration to which the cells were exposed in the medium. Cadmium-treated cells synthesized proteins de novo with the characteristics of cadmium-thionein induced in the liver of cadmium-treated animals. Thionein from liver cells incorporated cadmium and [35S]cysteine, had a Ve/Vo (Sephadex G-50) of 1.8-1.9, and was separated into two subfractions by DEAE-cellulose ion-exchange chromatography. Cycloheximide and actinomycin D when added after a cadmium exposure prevented the synthesis of thionein. However, addition of actinomycin D after synthesis had started only decreased the total amount of thionein synthesized. The concentration of cadmium to which the cells were exposed affected the amount of cadmium-thionein synthesized in 6h. The maximum response occurred when cells were exposed to 0.5 microgram of cadmium/ml; at higher metal concentrations the total amount of cadmium-thionein synthesized declined. The system described in the present paper can be used to study the mode of metal toxicity and the mechanism of cadmium-thionein synthesis.
分离的肝细胞对镉的摄取与培养基中细胞所接触的镉浓度呈线性关系。经镉处理的细胞重新合成具有在镉处理动物肝脏中诱导产生的镉硫蛋白特性的蛋白质。肝细胞中的硫蛋白结合了镉和[35S]半胱氨酸，其Ve/Vo（葡聚糖G - 50）为1.8 - 1.9，并通过DEAE - 纤维素离子交换色谱法分离为两个亚组分。镉暴露后添加放线菌酮和放线菌素D可阻止硫蛋白的合成。然而，在合成开始后添加放线菌素D只会减少硫蛋白的总合成量。细胞所接触的镉浓度影响6小时内合成的镉硫蛋白量。当细胞接触0.5微克镉/毫升时出现最大反应；在更高的金属浓度下，合成的镉硫蛋白总量下降。本文所述系统可用于研究金属毒性模式和镉硫蛋白合成机制。
