Cellular detoxification of tripeptidyl aldehydes by an aldo-keto reductase.
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.
Inoue
S
S
Department of Biological Sciences, Stanford University, California 94305-5020.
Sharma
R C
RC
Schimke
R T
RT
Simoni
R D
RD
D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002478:Cells, Cultured; D006224:Cricetinae; D003583:Cytokinins / Q000378:metabolism*; D004351:Drug Resistance; D006801:Humans; D007976:Leupeptins / Q000037:antagonists & inhibitors / Q000633:toxicity*; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000037:antagonists & inhibitors / Q000633:toxicity*; D011480:Protease Inhibitors / Q000378:metabolism / Q000633:toxicity*
D003583:Cytokinins; D007976:Leupeptins; D009842:Oligopeptides; D011480:Protease Inhibitors; C063261:acetylleucyl-leucyl-norleucinal; C069861:calpain inhibitor 2; D000429:Alcohol Oxidoreductases; C105564:CHO aldo-keto reductase