IRF-2 is involved in up-regulation of nonmuscle myosin heavy chain II-A gene expression during phorbol ester-induced promyelocytic HL-60 differentiation.
Transcription of the nonmuscle myosin heavy chain II-A (NMHC-A) gene is regulated by various factors, including cell type, proliferation and differentiation stage, and extracellular stimuli. We have identified an intronic region (designated 32kb-150), which is located 32 kb downstream of the transcription start sites in the human NMHC-A gene, as a transcriptional regulatory region. 32kb-150 contains an interferon-stimulated response element (ISRE). By using HeLa and NIH3T3 cells, in which NMHC-A is constitutively expressed, interferon regulatory factor (IRF)-2 was found to be the only major protein, among the IRF family proteins, that bound to the ISRE in 32kb-150 both in vitro and in intact cells. IRF-2, which is known to either repress or activate target gene expression, acts as a transcriptional activator in the context of the 32kb-150 reporter gene. The carboxyl-terminal basic region of IRF-2 serves as an activation domain in this context. This is in contrast to its acting as a repressor domain in the context of the synthetic core ISRE. Furthermore, after treatment of promyelocytic HL-60 cells with 12-O-tetradecanoylphorbol-13-acetate (TPA), which triggers differentiation into macrophages, both NMHC-A expression and IRF-2 expression were found to be up-regulated with a similar time course. TPA treatment leads to recruitment of IRF-2 to 32kb-150 of the endogenous NMHC-A gene and acetylation of the core histones surrounding this region. In addition, the ISRE in the 32kb-150 reporter gene recruits IRF-2 and mediates TPA-induced activation of a reporter gene in HL-60 cells. Together, these results indicate that IRF-2 contributes to transcriptional activation of the NMHC-A gene via 32kb-150 during TPA-induced differentiation of HL-60 cells.
Chung
Myung-Chul
MC
Laboratory of Molecular Cardiology, National Heart, Lung, and Blood Institute/NIH, 10 Center Drive, Bethesda, MD 20892, USA.
Kawamoto
Sachiyo
S
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002448:Cell Adhesion; D002454:Cell Differentiation; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005822:Genetic Vectors; D018922:HL-60 Cells; D006367:HeLa Cells; D006801:Humans; D050836:Interferon Regulatory Factor-2; D007438:Introns; D008156:Luciferases / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008957:Models, Genetic; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D024507:Nonmuscle Myosin Type IIA / Q000096:biosynthesis*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*; D012689:Sequence Homology, Nucleic Acid; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D015854:Up-Regulation
D004268:DNA-Binding Proteins; C494229:IRF2 protein, human; D050836:Interferon Regulatory Factor-2; C494230:Irf2 protein, mouse; D012097:Repressor Proteins; D014157:Transcription Factors; D008156:Luciferases; D024507:Nonmuscle Myosin Type IIA; D013755:Tetradecanoylphorbol Acetate