AML3/CBFα1 is required for androgen-specific activation of the enhancer of the mouse sex-limited protein (Slp) gene
AML3/CBFα1 is required for androgen-specific activation of the enhancer of the mouse sex-limited protein (Slp) gene
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DOI：
10.1074/jbc.274.43.30624
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发表时间：
1999-10-22
影响因子：
4.8
通讯作者：
Robins, DM
中科院分区：
文献类型：
--
作者：
Ning, YM;Robins, DM
一个复杂的120个碱基对的增强子，来自小鼠性限制蛋白（Slp）基因，在特定组织中仅由雄激素受体（AR）激活，尽管它包含一个激素反应元件，由几个类固醇受体识别。这种转录特异性的产生归因于受体与结合到增强子内的辅助位点的组织特异性非受体因子的相互作用。蛋白质-DNA相互作用测定揭示了两种因子结合增强子的5'部分，与那些也允许通过糖皮质激素受体（GR）激活的因子相比，这两种因子在显示Sip元件的AR特异性激活的细胞之间的丰度差异很大。命名为B的因子形成以序列TGTGGT为中心的复合物，该序列是AML/CBF α转录因子家族成员识别的核心基序。该复合物被AML/CBF α特异性的高亲和力结合位点竞争，并被AML 3/CBF α 1的抗体特异性超移位，将因子B置于AML 3/CBF α 1亚类内。有趣的是，该因子显示结合增强子3'部分的第二个位点，位于两个关键AR结合位点之间。转染研究表明，AML 1-ETO，一种显性阴性AML/CBF α构建体，废除了增强子的AR诱导，但不是简单的激素反应元件。此外，AML 3/CBF α 1的过表达可挽救AML 1-ETO抑制。最后，谷胱甘肽S-转移酶-AML/CBF α融合蛋白证实了AML/ CBF α与类固醇受体之间的直接相互作用。尽管这种相互作用在AML 1/CBF α 2和AR或GR之间是等效的，但AML 3/CBF α 1与AR的相互作用比与GR的相互作用更强。这些数据表明，AML 3/CBF α 1在功能上是Sip增强子的激素诱导所必需的，并且直接的、优先的蛋白质-蛋白质相互作用可能有助于AR特异性激活。这些结果证明了AML 3/ CBF α 1在类固醇以及靶基因的组织特异性激活中的有趣作用。
A complex 120-base pair enhancer, derived from the mouse sex-limited protein (Slp) gene, is activated solely by the androgen receptor (AR) in specific tissues, although it contains a hormone response element recognized by several steroid receptors. The generation of this transcriptional specificity has been ascribed to the interactions of the receptor with tissue-specific nonreceptor factors bound to accessory sites within the enhancer. Protein-DNA interaction assays revealed two factors binding the 5' part of the enhancer that differ widely in abundance between cells showing AR-specific activation of the Sip element compared with those that also permit activation by glucocorticoid receptor (GR). The factor designated B formed a complex centered on the sequence TGTGGT, a core motif recognized by members of the AML/CBF alpha transcription factor family. This complex was competed by a high affinity binding site specific for AML/CBF alpha and was specifically supershifted by an antibody to AML3/CBF alpha 1, placing factor B within the AML3/CBF alpha 1 subclass. Interestingly, this factor was shown to bind to a second site in the 3' part of the enhancer, positioned between the two critical AR binding sites. Transfection studies revealed that AML1-ETO, a dominant-negative AML/CBF alpha construct, abrogated AR induction of the enhancer, but not of simple hormone response elements. Furthermore, overexpression of AML3/CBF alpha 1 could rescue the AML1-ETO repression. Finally, glutathione S-transferase-AML/CBF alpha fusion proteins demonstrated direct interaction between AML/ CBF alpha and steroid receptors. Although this interaction was equivalent between AML1/CBF alpha 2 and AR or GR, AML3/CBF alpha 1 showed stronger interaction with AR than with GR. These data demonstrate that AML3/CBF alpha 1 is functionally required for hormonal induction of the Sip enhancer and that direct, preferential protein-protein interactions may contribute to AR-specific activation. These results demonstrate an intriguing role of AML3/ CBF alpha 1 in steroid- as well as tissue-specific activation of target genes.