title: Identification of target genes and a unique cis element regulated by IRF-8 in developing macrophages.
abstract: Interferon regulatory factor-8 (IRF-8)/interferon consensus sequence-binding protein (ICSBP) is a transcription factor that controls myeloid-cell development. Microarray gene expression analysis of Irf-8-/- myeloid progenitor cells expressing an IRF-8/estrogen receptor chimera (which differentiate into macrophages after addition of estradiol) was used to identify 69 genes altered by IRF-8 during early differentiation (62 up-regulated and 7 down-regulated). Among them, 4 lysosomal/endosomal enzyme-related genes (cystatin C, cathepsin C, lysozyme, and prosaposin) did not require de novo protein synthesis for induction, suggesting that they were direct targets of IRF-8. We developed a reporter assay system employing a self-inactivating retrovirus and analyzed the cystatin C and cathepsin C promoters. We found that a unique cis element mediates IRF-8-induced activation of both promoters. Similar elements were also found in other IRF-8 target genes with a consensus sequence (GAAANN[N]GGAA) comprising a core IRF-binding motif and an Ets-binding motif; this sequence is similar but distinct from the previously reported Ets/IRF composite element. Chromatin immunoprecipitation assays demonstrated that IRF-8 and the PU.1 Ets transcription factor bind to this element in vivo. Collectively, these data indicate that IRF-8 stimulates transcription of target genes through a novel cis element to specify macrophage differentiation.
authors.affiliation: Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, 6 Center Dr, MSC 2753, Bethesda, MD 20892-2753, USA. tamurat@mail.nih.gov
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Tamura
authors.forename: Pratima
authors.initials: P
authors.lastname: Thotakura
authors.forename: Tetsuya S
authors.initials: TS
authors.lastname: Tanaka
authors.forename: Minoru S H
authors.initials: MS
authors.lastname: Ko
authors.forename: Keiko
authors.initials: K
authors.lastname: Ozato
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D020789:Cathepsin C / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D016384:Consensus Sequence; D055316:Cystatin C; D015891:Cystatins / Q000235:genetics; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D050835:Interferon Regulatory Factors; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000502:physiology*; D014158:Transcription, Genetic; D000099185:Interferon Regulatory Factor-8
chemical_list: D020789:Cathepsin C; D055316:Cystatin C; D015891:Cystatins; D050835:Interferon Regulatory Factors; D012097:Repressor Proteins; D000099185:Interferon Regulatory Factor-8; C525031:Cst3 protein, mouse