The SCL complex regulates c-kit expression in hematopoietic cells through functional interaction with Sp1
The SCL complex regulates c-kit expression in hematopoietic cells through functional interaction with Sp1
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DOI：
10.1182/blood-2002-02-0568
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发表时间：
2002-10-01
期刊：
影响因子：
20.3
通讯作者：
Hoang, T
中科院分区：
文献类型：
--
作者：
Lécuyer, E;Herblot, S;Hoang, T
转录因子之间的组合相互作用被认为决定造血细胞的命运。干细胞白血病（Stem cell leukemia，SCL）是一种组织特异性碱性螺旋-环-螺旋（basic helix-loop-helix，bHLH）因子，在造血系统发育中发挥重要作用，但其作用靶基因和分子机制尚不清楚。在这里，我们表明，SCL和c-kit受体共表达在造血祖细胞在单细胞水平和SCL诱导c-kit在染色质中，作为异位SCL在转基因小鼠的表达维持c-kit转录在发展中的B淋巴细胞，其中两个基因通常下调。通过瞬时转染试验和内源性蛋白质的免疫共沉淀，我们定义了SCL作为多因子复合物（SCL复合物）的成核因子的作用，该复合物特异性地增强c-kit启动子活性而不影响骨髓单核细胞启动子的活性。该复合物含有造血特异性（SCL，Lim-only 2（LMO 2），加塔-1/加塔-2）和普遍存在的（E2 A，LIM-结构域结合蛋白1 [Ldb-1]）因子，通过SCL复合物元件和Sp1锌指蛋白之间的直接相互作用，通过特异性蛋白1（Sp1）基序与DNA连接。此外，我们通过染色质免疫沉淀证明SCL，E2 A和Sp1在体内特异性地共同占据c-kit启动子。因此，我们得出结论，c-kit是SCL复合物的直接靶标。c-kit启动子的正确激活取决于复合物所有成员的组合相互作用。由于SCL在成熟细胞中下调，而其伴侣保持表达，我们的观察表明SCL的缺失使SCL复合物失活，这可能是多能造血细胞分化中的重要事件。(C)2002年，美国血液学会。
The combinatorial interaction among transcription factors is believed to determine hematopoietic cell fate. Stem cell leukemia (SCL, also known as TAL1 [T-cell acute lymphoblastic leukemia 1]) is a tissue-specific basic helix-loop-helix (bHLH) factor that plays a central function in hematopoietic development; however, Its target genes and molecular mode of action remain to be elucidated. Here we show that SCL and the c-kit receptor are coexpressed in hematopoietic progenitors at the single-cell level and that SCL Induces c-kit In chromatin, as ectopic SCL expression in transgenic mice sustains c-kit transcription in developing B lymphocytes, in which both genes are normally down-regulated. Through transient transfection assays and coimmunoprecipitation of endogenous proteins, we define the role of SCL as a nucleation factor for a multifactorial complex (SCL complex) that specifically enhances c-kit promoter activity without affecting the activity of myelomonocytic promoters. This complex, containing hematopoietic-specific (SCL, Lim-only 2 (LMO2), GATA-1/GATA-2) and ubiquitous (E2A, LIM-domain binding protein 1 [Ldb-1]) factors, is tethered to DNA via a specificity protein 1 (Sp1) motif, through direct Interactions between elements of the SCL complex and the Sp1 zinc finger protein. Furthermore, we demonstrate by chromatin Immunoprecipitation that SCL, E2A, and Sp1 specifically co-occupy the c-kit promoter in vivo. We therefore conclude that c-kit is a direct target of the SCL complex. Proper activation of the c-kit promoter depends on the combinatorial Interaction of all members of the complex. Since SCL Is down-regulated in maturing cells while Its partners remain expressed, our observations suggest that loss of SCL inactivates the SCL complex, which may be an Important event in the differentiation of pluripotent hematopoietic cells. (C) 2002 by The American Society of Hematology.