title: Downregulation of GATA-1 expression during phorbol myristate acetate-induced megakaryocytic differentiation of human erythroleukemia cells.
abstract: Phorbol myristate acetate (PMA) induces the expression of megakaryocyte and/or platelet proteins during terminal differentiation of human erythroleukemia (HEL) cells. However, it is not established whether megakaryocytic differentiation is accompanied by the downregulation of the major erythroid transcription factor GATA-1 and the concomitant loss of the erythrocytic phenotype. Studies of the molecular mechanism of PMA-induced differentiation in HEL cells showed that when HEL cells are treated with PMA, they dramatically decrease the expression of the erythroid-specific gene glycophorin A at the mRNA level but apparently not at the steady-state protein level. In addition, a gel mobility shift assay was used to demonstrate that GATA-1, a major erythroid transcription factor normally present at high levels in HEL cells is downregulated after treatment with PMA. In contrast, the DNA-binding activities of transcription factors AP-1 and SP-1 are upregulated by PMA treatment of HEL cells. Furthermore, Northern blot analysis shows that PMA also downregulates the steady-state level of GATA-1 mRNA in HEL cells. The coordinated negative regulation of glycophorin A mRNA and GATA-1 expression after PMA treatment suggests that downregulation of GATA-1 expression may be partially responsible for the loss of the erythroid phenotype during megakaryocytic differentiation. The reported data also suggest that GATA-1 activity may not be essential for obtaining megakaryocytic phenotype during terminal differentiation in HEL cells.
authors.affiliation: Molecular Biology Laboratory, Hipple Cancer Research Center, Dayton, OH 45439-2092.
authors.forename: W
authors.initials: W
authors.lastname: Dai
authors.forename: M J
authors.initials: MJ
authors.lastname: Murphy
mesh_terms: D001483:Base Sequence; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D015536:Down-Regulation; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; D005786:Gene Expression Regulation; D006021:Glycophorins / Q000235:genetics; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism* / Q000473:pathology; D008533:Megakaryocytes / Q000502:physiology*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014157:Transcription Factors / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D050982:GATA1 Transcription Factor; C494688:GATA1 protein, human; D006021:Glycophorins; D012333:RNA, Messenger; D014157:Transcription Factors; D013755:Tetradecanoylphorbol Acetate