Abnormal accumulation and toxicity of polyamines in a difluoromethylornithine-resistant HTC cell variant.
Abnormal accumulation and toxicity of polyamines in a difluoromethylornithine-resistant HTC cell variant.
复制标题
二氟甲基鸟氨酸抗性 HTC 细胞变体中多胺的异常积累和毒性。
DOI：
10.1016/0167-4889(92)90248-a
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Mitchell,JL
中科院分区：
文献类型：
--
作者：
Mitchell,JL;DiveleyJr,RR;Bareyal-Leyser,A;Mitchell,JL
哺乳动物细胞具有可诱导的、主动的多胺转运系统，该系统受到反馈控制的严格调节。这项研究提供的证据表明，DH23 b细胞，这是最初选择从大鼠肝癌HTC系的鸟氨酸脱羧酶的过度生产，表现出异常的多胺转运的调节。这些细胞暴露于微摩尔水平的亚精胺或精胺导致蛋白质合成的抑制和最终的细胞裂解。这些影响是不是由于副产品的多胺氧化血清氧化酶既不抑制蛋白质的合成，也不细胞裂解减轻氨基胍，还原型谷胱甘肽，二硫苏糖醇，或过氧化氢酶。虽然DH23b细胞中的多胺转运系统与亲本HTC系中的多胺转运系统具有相同的KmandVmax，但变异细胞积累了异常高水平的亚精胺（8倍于正常值）和精胺（4倍于正常值）。然而，在HTC线，运输的多胺以及腐胺反馈抑制约。3 h，而在变体细胞中，摄取在12 h时未减少，仅以细胞裂解终止。DH23b细胞似乎缺乏负责活性多胺掺入的反馈控制的正常机制。这一缺陷提供了机会，以操纵细胞内水平的亚精胺从30至约。正常值的800%，这表明细胞蛋白质合成对亚精胺水平的敏感性与以前的体外研究所表明的一样。
Mammalian cells possess an inducible, active polyamine transport system that is stringently regulated by feedback controls. This study provides evidence that DH23b cells, which were initially selected from the rat hepatoma HTC line for overproduction of ornithine decar☐ylase, demonstrate an abnormality in the regulation of polyamine transport. Exposure of these cells to micromolar levels of spermidine or spermine resulted in inhibition of protein synthesis and eventual cell lysis. These effects were not due to by-products of polyamine oxidation by serum oxidases as neither inhibition of protein synthesis nor cell lysis was mitigated by aminoguanidine, reduced glutathione, dithiothreitol, or catalase. Although the polyamine transport system in the DH23b cells has the sameKmandVmaxas that in the parental HTC line, the variant cells accumulated abnormally high levels of both spermidine (8-times normal) and spermine (4-times normal). In the HTC line, however, transport of both polyamines as well as putrescine was feedback inhibited within approx. 3 h, while in the variant cells uptake was not diminished by 12 h and terminated only with cell lysis. The DH23b cells appear to lack the normal mechanism responsible for feedback control of active polyamine incorporation. This defect provided the opportunity to manipulate intracellular levels of spermidine from 30 to approx. 800% of normal, allowing the demonstration that cellular protein synthesis is as sensitive to spermidine levels as previous in-vitro studies had suggested.