Hewitt S M, Fraizer G C, Wu Y J, Rauscher F J, Saunders G F
Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston, 77030, USA.
J Biol Chem. 1996 Apr 12;271(15):8588-92. doi: 10.1074/jbc.271.15.8588.
The Wilms' tumor gene, WT1, encodes a zinc finger transcription factor that can repress transcription of a number of genes. WT1 mRNA undergoes alternative splicing at two locations, yielding four different mRNA species and protein products. One alternative splice alters the zinc finger region of WT1, resulting in the addition of three amino acids, Lys-Thr-Ser (KTS), between zinc fingers 3 and 4, altering the binding of WT1 to DNA. Here, we show that the WT1 protein with and without the KTS tripeptide can repress transcription from the human full-length WT1 promoter. Repression of transcription by WT1 has been shown to require two WT1 binding sites. We examined WT1 repression of the human minimal WT1 promoter, which contains two potential WT1 binding motifs. WT1 lacking the KTS tripeptide (WT1-KTS) was unable to repress transcription from a minimal WT1 promoter of 104 base pairs, whereas WT1 containing the KTS tripeptide (WT1+KTS) repressed transcription from the minimal promoter. The ability of WT1+KTS to repress transcription where WT1-KTS could not provided a functional assay to define differential WT1 binding motifs based on the presence or the absence of the KTS tripeptides. We present data defining the differential consensus DNA binding motifs for WT1-KTS and WT1+KTS. We demonstrate that WT1 zinc finger 1 plays a role in the differential DNA binding specificity of WT1-KTS and WT1+KTS.
威尔姆斯瘤基因WT1编码一种锌指转录因子，该因子可抑制许多基因的转录。WT1信使核糖核酸（mRNA）在两个位点进行可变剪接，产生四种不同的mRNA种类和蛋白质产物。一种可变剪接改变了WT1的锌指区域，导致在锌指3和4之间添加了三个氨基酸，即赖氨酸-苏氨酸-丝氨酸（KTS），从而改变了WT1与DNA的结合。在此，我们表明，含有和不含有KTS三肽的WT1蛋白均可抑制人全长WT1启动子的转录。WT1对转录的抑制作用已被证明需要两个WT1结合位点。我们研究了WT1对人最小WT1启动子的抑制作用，该启动子包含两个潜在的WT1结合基序。缺乏KTS三肽的WT1（WT1-KTS）无法抑制104个碱基对的最小WT1启动子的转录，而含有KTS三肽的WT1（WT1+KTS）则可抑制最小启动子的转录。WT1+KTS在WT1-KTS无法抑制转录的情况下抑制转录的能力，提供了一种功能测定方法，可根据KTS三肽的存在与否来定义不同的WT1结合基序。我们展示了定义WT1-KTS和WT1+KTS不同共有DNA结合基序的数据。我们证明WT1锌指1在WT1-KTS和WT1+KTS的不同DNA结合特异性中发挥作用。
