Inoue S, Sharma R C, Schimke R T, Simoni R D
Department of Biological Sciences, Stanford University, California 94305-5020.
J Biol Chem. 1993 Mar 15;268(8):5894-8.
Calpain inhibitor I, N-acetyl-leucyl-leucyl-norleucinal (ALLN), a cell-permeable synthetic tripeptide with an aldehyde at its C terminus specifically inhibits the activity of cysteine proteases. Since the regulated degradation of 3-hydroxy-3-methylglutaryl-CoA reductase in Chinese hamster ovary (CHO) cells is blocked by ALLN and ALLN has a cytotoxic effect on cells, we attempted to isolate ALLN-resistant cells that overproduce an ALLN-sensitive protease(s). However, we obtained an ALLN-resistant cell line that overproduced P-glycoprotein (Sharma, R. C., Inoue, S., Roitelman, J., Schimke, R. T., and Simoni, R. D. (1992) J. Biol. Chem. 267, 5731-5734). To circumvent the multidrug resistance (MDR) phenotype during selection, we have stepwise selected an ALLN-resistant cell line of CHO cells in the presence of verapamil, a competitive inhibitor of P-glycoprotein. These non-MDR ALLN-resistant cells overexpress a 35-kDa protein and have increased aldo-keto reductase activity. Partial amino acid sequences of the 35-kDa protein are highly homologous to members of the aldo-keto reductase superfamily. The aldo-keto reductases are NADPH-dependent oxidoreductases and catalyze reduction of a wide range of carbonyl compounds such as aldehydes, sugars, and ketones. Our findings support the concept that a physiological function for aldo-keto reductases may be detoxification.
钙蛋白酶抑制剂I，N-乙酰基-亮氨酰-亮氨酰-正亮氨酸醛（ALLN），一种可透过细胞的合成三肽，其C末端含有醛基，能特异性抑制半胱氨酸蛋白酶的活性。由于中国仓鼠卵巢（CHO）细胞中3-羟基-3-甲基戊二酰辅酶A还原酶的调节性降解被ALLN阻断，且ALLN对细胞具有细胞毒性作用，我们试图分离出过量产生ALLN敏感蛋白酶的ALLN抗性细胞。然而，我们获得了一个过量产生P-糖蛋白的ALLN抗性细胞系（沙尔马，R.C.，井上，S.，罗伊特尔曼，J.，施姆克，R.T.，和西蒙尼，R.D.（1992年）《生物化学杂志》267，5731 - 5734）。为了在选择过程中规避多药耐药（MDR）表型，我们在维拉帕米（一种P-糖蛋白的竞争性抑制剂）存在的情况下逐步筛选出了CHO细胞的ALLN抗性细胞系。这些非MDR ALLN抗性细胞过量表达一种35 kDa的蛋白质，并且醛糖酮还原酶活性增加。该35 kDa蛋白质的部分氨基酸序列与醛糖酮还原酶超家族成员高度同源。醛糖酮还原酶是依赖NADPH的氧化还原酶，催化多种羰基化合物如醛、糖和酮的还原反应。我们的研究结果支持这样一种观点，即醛糖酮还原酶的生理功能可能是解毒。
