A central role for a single c-Myb binding site in a thymic locus control region.
A central role for a single c-Myb binding site in a thymic locus control region.
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胸腺基因座控制区中单个 c-Myb 结合位点的核心作用。
DOI：
10.1128/mcb.15.10.5707
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发表时间：
1995
影响因子：
5.3
通讯作者：
Aronow,BJ
中科院分区：
文献类型：
--
作者：
Ess,KC;Whitaker,TL;Cost,GJ;Witte,DP;Hutton,JJ;Aronow,BJ
基因座控制区（Locus control regions，LCR）是顺式元件的强有力的集合体，它组织细胞类型特异性反式作用因子的活动。人腺苷脱氨酶（ADA）基因第一内含子中的2.3 kb LCR控制胸腺细胞中的表达，由200 bp增强子结构域和促进染色质内激活的延伸侧翼序列组成。先前的分析表明，增强子包含一个28 bp的核心区域和局部相邻的增强子元件。我们现在表明，核心包含一个关键的c-Myb结合位点。在瞬时共转染的人类细胞和稳定的染色质整合的酵母细胞中，c-Myb强烈反式激活的报告结构，包含聚合的核心序列。c-Myb蛋白在T淋巴母细胞中非常明显，其中增强子是活性的，并且定位在离散的核结构内。胎鼠胸腺内源性c-myb表达与小鼠ADA和人ADA LCR定向转基因表达具有显著一致性。在完整的2.3 kb LCR内的c-Myb位点的点突变严重减弱了转染中的增强子活性和转基因胸腺细胞中的LCR活性。在复合增强子和LCR的背景下，c-Myb可以通过单个结合位点作为胸腺细胞特异性基因表达的组织者。
Locus control regions (LCRs) are powerful assemblies ofciselements that organize the actions of cell-type-specifictrans-acting factors. A 2.3-kb LCR in the human adenosine deaminase (ADA) gene first intron, which controls expression in thymocytes, is composed of a 200-bp enhancer domain and extended flanking sequences that facilitate activation from within chromatin. Prior analyses have demonstrated that the enhancer contains a 28-bp core region and local adjacent augmentativeciselements. We now show that the core contains a single critical c-Myb binding site. In both transiently cotransfected human cells and stable chromatin-integrated yeast cells, c-Myb strongly transactivated reporter constructs that contained polymerized core sequences. c-Myb protein was strongly evident in T lymphoblasts in which the enhancer was active and was localized within discrete nuclear structures. Fetal murine thymus exhibited a striking concordance of endogenous c-mybexpression with that of mouse ADA and human ADA LCR-directed transgene expression. Point mutation of the c-Myb site within the intact 2.3-kb LCR severely attenuated enhancer activity in transfections and LCR activity in transgenic thymocytes. Within the context of a complex enhancer and LCR, c-Myb can act as an organizer of thymocyte-specific gene expression via a single binding site.