Identification of target genes and a unique cis element regulated by IRF-8 in developing macrophages
Identification of target genes and a unique cis element regulated by IRF-8 in developing macrophages
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DOI：
10.1182/blood-2005-01-0080
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发表时间：
2005-09-15
期刊：
影响因子：
20.3
通讯作者：
Ozato, K
中科院分区：
文献类型：
--
作者：
Tamura, T;Thotakura, P;Ozato, K
干扰素调节因子-8 (IRF-8)/干扰素一致序列结合蛋白（ICSBP）是一种控制骨髓细胞发育的转录因子。通过对表达Irf-8 /雌激素受体嵌合体（加入雌二醇后分化为巨噬细胞）的Irf-8（-/-）髓系祖细胞的微阵列基因表达分析，鉴定了69个在早期分化过程中被Irf-8改变的基因（62个上调，7个下调）。其中4个溶酶体/内体酶相关基因（胱抑素C、组织蛋白酶C、溶菌酶和丙皂苷）不需要从头合成蛋白即可诱导，提示它们是IRF-8的直接靶点。我们开发了一种采用自灭活逆转录病毒的报告基因检测系统，并分析了胱抑素C和组织蛋白酶C启动子。我们发现一个独特的顺式元件介导irf -8诱导的两个启动子的激活。在其他IRF-8靶基因中也发现了类似的元件，其一致序列（GAAANN[N]GGAA）包括一个核心irf -结合基序和一个ets -结合基序；该序列与先前报道的Ets/IRF复合元素相似但不同。染色质免疫沉淀实验表明，IRF-8和PU.1 Ets转录因子在体内与该元件结合。总的来说，这些数据表明IRF-8通过一种新的顺式元件刺激靶基因的转录，以指定巨噬细胞分化。
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.