Fibroblasts that express aromatic amino acid decarboxylase have increased sensitivity to the synergistic cytotoxicity of L-dopa and manganese.
Fibroblasts that express aromatic amino acid decarboxylase have increased sensitivity to the synergistic cytotoxicity of L-dopa and manganese.
复制标题
表达芳香族氨基酸脱羧酶的成纤维细胞对左旋多巴和锰的协同细胞毒性的敏感性增加。
DOI：
10.1006/taap.1994.1188
复制
发表时间：
1994
影响因子：
3.8
通讯作者：
Graham,DG
中科院分区：
文献类型：
--
作者：
Montine,TJ;Underhill,TM;Linney,E;Graham,DG
锰中毒是一种神经退行性疾病，可在长期暴露于锰后发生，与基底神经节病变和该脑区多巴胺及其代谢物耗竭相关。在此，我们已经测试了这一假设，儿茶酚的氧化是锰诱导的细胞毒性的关键组成部分。为了消除混杂的代谢途径，非神经元细胞系，中国仓鼠卵巢（CHO）成纤维细胞，转染牛芳香族氨基酸脱羧酶的cDNA，并分离出高表达克隆（CHO/AADC）。将野生型（CHO/WT）或CHO/ AADC培养物暴露于L-多巴（62 - 500 μM）分别导致L-多巴或L-多巴和多巴胺的细胞内蓄积，这是浓度依赖性的。CHO/AADC细胞中的细胞内儿茶酚水平是CHO/WT培养物中的两倍。细胞内或细胞外均未发现多巴酚丁胺。添加MnCl 2（125至500 μM）导致细胞毒性，随着左旋多巴或Mn浓度的增加而增加。无论是左旋多巴，也不是氯化锰，单独在这些浓度是有毒的，细胞毒性完全废除的L-酪氨酸取代左旋多巴。虽然CHO/AADC培养物比CHO/WT对左旋多巴和锰更敏感，但这完全是由两种细胞系之间细胞内儿茶酚水平的差异造成的。预形成的黑色素或多巴酚是低效力的细胞毒素，只有在高浓度的氯化锰。这些结果表明，锰和细胞内左旋多巴和多巴胺，但不是细胞外多巴或黑色素，是有效的协同细胞毒素。
Manganism, a neurodegenerative disease that can follow chronic exposure to Mn, has been associated with lesions in the basal ganglia and depletion of dopamine and its metabolites in this brain region. Herein, we have tested the hypothesis that oxidation of catechols is a critical component of Mn-induced cytotoxicity. To eliminate confounding metabolic pathways, a nonneuronal cell line, Chinese hamster ovary (CHO) fibroblasts, was transfected with a cDNA for bovine aromatic amino acid decarboxylase, and a high expressing clone was isolated (CHO/AADC). Exposure of wild-type (CHO/WT) or CHO/ AADC cultures to L-dopa (62 to 500 μM) resulted in intracellular accumulation of L-dopa or L-dopa and dopamine, respectively, that was concentration-dependent. Intracellular catechol levels in CHO/AADC cells were double those in CHO/WT cultures. No dopac was identified intra- or extracellularly. Addition of MnCl2(125 to 500 μM) resulted in cytotoxicity that progressed with increasing concentrations of L-dopa or Mn. Neither L-dopa nor MnCl2, alone was toxic at these concentrations, and cytotoxicity was completely abrogated by substitution of L-tyrosine for L-dopa. Although CHO/AADC cultures were more sensitive than CHO/WT to L-dopa and Mn, this was completely accounted for by the differences in intracellular catechol levels between the two cell lines. Preformed melanin or dopac were low-potency cytotoxins only at high MnCl2concentrations. These results indicate that Mn and intracellular L-dopa and dopamine, but not extracellular dopac or melanin, are potent synergistic cytotoxins.