AML1A and AML1B can transactivate the human IL-3 promoter.
AML1A and AML1B can transactivate the human IL-3 promoter.
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DOI：
10.4049/jimmunol.158.5.2251
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发表时间：
1997-03
影响因子：
4.4
通讯作者：
Hideo Uchida;Jin Zhang;Stephen D. Nimer
中科院分区：
文献类型：
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作者：
Hideo Uchida;Jin Zhang;Stephen D. Nimer
AML1 基因编码多种转录因子，包括 AML1A 和 AML1B，它们通过 TGT/cGGT 共有序列与 DNA 结合，该共有序列存在于多个启动子（包括人 IL-3 启动子）中。我们在 T 细胞中进行了共转染实验，并证明尽管 AML1A 缺乏推定的反式激活结构域，但它几乎可以与已知激活剂 AML1B 一样有效地反式激活 IL-3 启动子。共有 AML1 结合位点 (TGTGGT) 位于先前鉴定的人 IL-3 启动子的 DNase I 足迹区域 A（从 bp -165 到 -128），以及与共有结合位点 (TGTGGG) 相似的序列，位于足迹区域 B（bp -55 到 -42），在凝胶迁移测定中特异性结合 AML1 蛋白。 TGTGGG 序列的亲和力远低于 TGTGGT 序列的亲和力，并且 TGTGGG 序列突变不会改变 IL-3 启动子活性，而共有结合位点的突变降低了基础启动子活性，几乎消除了 AML1A 和 AML1B 的反式激活。由 t(8;21) 易位产生的 AML1/ETO 融合蛋白抑制 IL-3 启动子活性，尽管 AML1/ETO 的 AML1 部分（氨基酸 1-177）缺乏转录调节活性并且在体外不与 DNA 结合。 AML1 的 60 至 177 个氨基酸部分很容易结合 DNA，表明前 59 个氨基酸可能充当 DNA 结合的抑制域。 AML1A 的反式激活和假定的抑制性结合域的定位的证明表明该转录因子家族内的额外复杂性。
The AML1 gene encodes several transcription factors, including AML1A and AML1B, which bind to DNA via a TGT/cGGT consensus sequence that is found in several promoters, including the human IL-3 promoter. We performed cotransfection experiments in T cells, and demonstrated that although AML1A lacks a putative transactivation domain, it can transactivate the IL-3 promoter nearly as effectively as AML1B, a known activator. A consensus AML1 binding site (TGTGGT), located in the previously identified DNase I footprint region A of the human IL-3 promoter (extending from bp -165 to -128), and a sequence similar to the consensus binding site (TGTGGG), located in footprint region B (bp -55 to -42), specifically bind AML1 proteins in gel shift assays. The affinity for the TGTGGG sequence was much less than that for the TGTGGT sequence, and mutating the TGTGGG sequence did not alter the IL-3 promoter activity, whereas mutation of the consensus binding site decreased the basal promoter activity and nearly eliminated transactivation by AML1A and AML1B. The AML1/ETO fusion protein, generated by the t(8;21) translocation, repressed IL-3 promoter activity, although the AML1 portion of AML1/ETO (amino acids 1-177) lacked transcriptional regulatory activity and did not bind to DNA in vitro. The 60- to 177-amino acid portion of AML1 readily bound DNA, suggesting that the first 59 amino acids may function as an inhibitory domain for DNA binding. Demonstration of the transactivation by AML1A and localization of a putative inhibitory binding domain suggest additional complexity within this family of transcription factors.