Impaired erythroid-specific gene expression in cAMP-dependent protein kinase-deficient murine erythroleukemia cells.
Murine erythroleukemia cells rendered deficient in cAMP-dependent protein kinase (A-kinase) activity by gene transfection are severely impaired in hexamethylene bisacetamide (HMBA)-induced differentiation (Pilz, R. B., Eigenthaler, M., and Boss, G. R. (1992) J. Biol. Chem. 267, 16161-16167). We now demonstrate that the A-kinase-deficient cells produce hemoglobin normally in response to exogenous hemin and that the heme precursor delta-aminolevulinate (delta-ALA) significantly increases HMBA-induced synthesis of heme and globin chains in these cells; these data suggest that impaired heme synthesis is at least partially responsible for the cells' deficient hemoglobin synthesis. HMBA-induced expression of the erythroid-specific delta-ALA synthetase, porphobilinogen deaminase, and beta-globin mRNAs was less in A-kinase-deficient cells than in parental cells and was reduced in proportion to the cells' residual A-kinase activity; relative transcription rates of these genes were reduced concordantly. Impaired expression of these three erythroid-specific genes was a feature of many independently-derived A-kinase-deficient clones, and normal expression was found in transfectants with normal A-kinase activity. The A-kinase-deficient cells did not exhibit a generalized defect in gene regulation since mRNA expression and transcription rates of H- and L-ferritin, c-myc, c-myb, and several housekeeping enzymes were similar in HMBA-treated parental and A-kinase-deficient cells. Our data suggest that A-kinase may be involved in regulating genes with erythroid-specific promoters and provide further evidence for heme as a regulator of globin chain synthesis.
Department of Medicine, University of California, San Diego, La Jolla 92093-0652.
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D000624:5-Aminolevulinate Synthetase / Q000096:biosynthesis*; D000081:Acetamides / Q000494:pharmacology; D000622:Aminolevulinic Acid / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D005293:Ferritins / Q000096:biosynthesis; D015870:Gene Expression; D016259:Genes, myc / Q000187:drug effects; D005914:Globins / Q000096:biosynthesis*; D006397:Hematinics / Q000494:pharmacology; D006418:Heme / Q000096:biosynthesis / Q000378:metabolism; D006427:Hemin / Q000494:pharmacology; D006454:Hemoglobins / Q000096:biosynthesis*; D011163:Hydroxymethylbilane Synthase / Q000096:biosynthesis*; D004915:Leukemia, Erythroblastic, Acute / Q000201:enzymology / Q000378:metabolism*; D007942:Leukemia, Experimental / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D009857:Oncogenes / Q000187:drug effects; D011494:Protein Kinases / Q000172:deficiency*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014407:Tumor Cells, Cultured
D000081:Acetamides; D006397:Hematinics; D006454:Hemoglobins; D012333:RNA, Messenger; D006418:Heme; D006427:Hemin; D000622:Aminolevulinic Acid; D005914:Globins; D005293:Ferritins; D000624:5-Aminolevulinate Synthetase; D011163:Hydroxymethylbilane Synthase; D011494:Protein Kinases; C014026:hexamethylene bisacetamide