title: Negative and positive regulation of human leukocyte antigen class I gene transcription in K562 leukemia cells.
abstract: The mechanism of transcriptional activation of human leukocyte antigen class I genes by gamma interferon and 5-azacytidine was studied in K562 human leukemia cells. Nuclear run-on transcription assays with various protein and RNA synthesis inhibitors yield evidence for both stimulation of a positive regulatory factor and inhibition of an mRNA that codes for a labile repressor. A novel mechanism is proposed to explain how 5-azacytidine can activate repressed genes without affecting DNA methylation.
mesh_terms: D001374:Azacitidine / Q000494:pharmacology; D004273:DNA, Neoplasm / Q000096:biosynthesis / Q000378:metabolism; D004357:Drug Synergism; D005786:Gene Expression Regulation; D006680:HLA Antigens / Q000235:genetics*; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007700:Kinetics; D007938:Leukemia / Q000276:immunology*; D008745:Methylation; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D004273:DNA, Neoplasm; D006680:HLA Antigens; D012333:RNA, Messenger; D007371:Interferon-gamma; D001374:Azacitidine