Regulation of the human cellular glutathione peroxidase gene during in vitro myeloid and monocytic differentiation.
We have used the HL-60 and PLB-985 myeloid leukemia cell lines to examine the regulation of expression of the important intracellular antioxidant enzyme, glutathione peroxidase (GSH-Px), during phagocytic cell differentiation in vitro. Induction of differentiation along the monocytic pathway by phorbol ester results in an approximately twofold rise in enzyme activity and a parallel increase in the rate of 75Se incorporation into immunoprecipitable GSH-Px protein. Induction along the granulocytic pathway by dimethyl formamide (DMF) results in similar changes in steady-state enzyme levels and rates of GSH-Px protein synthesis. Steady-state levels of GSH-Px gene transcripts also increase more than twofold, approximately in parallel with the enzyme levels. Nuclear run-on transcription assays of GSH-Px mRNA synthesis show ratios of induced to uninduced transcript levels of 2.24 and 1.59 with phorbol myristate acetate (PMA) induction and DMF, respectively, in HL-60 cells, and ratios of 1.34 and 3.46 with PMA and DMF, respectively, in PLB-985 cells. Half lives of GSH-Px mRNA are unchanged or slightly shorter after differentiation of HL-60 cells, and slightly longer after induction of PLB-985. Overall, the present studies show that GSH-Px activity rises during in vitro-induced monocytic or granulocytic differentiation of myeloid cell lines and that the increased expression of the cellular GSH-Px gene occurs through complex mechanisms that include transcriptional up-regulation. This pattern contrasts with the nearly complete cotranslational regulation of GSH-Px expression by exogenous selenium.
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Department of Pediatrics, University of Massachusetts Medical School, Worcester 01655.
Chada
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Whitney
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Newburger
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D002454:Cell Differentiation / Q000187:drug effects; D004126:Dimethylformamide / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005979:Glutathione Peroxidase / Q000096:biosynthesis* / Q000235:genetics; D006098:Granulocytes; D006801:Humans; D007951:Leukemia, Myeloid / Q000473:pathology; D015473:Leukemia, Promyelocytic, Acute / Q000473:pathology; D008562:Membrane Glycoproteins; D009000:Monocytes; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics; D010586:Phagocytes / Q000201:enzymology*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D004126:Dimethylformamide; D005979:Glutathione Peroxidase; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D013755:Tetradecanoylphorbol Acetate