Analysis of DNA binding specificity in homeodomains (1-4) of ATBF1

DNA/RNA依赖性ATP酶活性与ATBF 1相关，ATBF 1是一种多同源结构域锌指蛋白（Biochimica et Biophysicica Acta）。我们研究了ATP酶活性是否与ATBF 1分子相关。ATBF 1分子的263个氨基酸片段（称为AHZ）含有ATP酶A基序、同源结构域IV和锌指21，在大肠杆菌中以GST融合蛋白的形式表达，并分析ATP酶活性。我们发现AHZ能够水解ATP，并具有结合DNA和RNA的能力。与ATBF 1相关的ATP酶活性是DNA/RNA依赖性的，并且是独特的，因为它需要同源结构域和锌指基序。Res. Commun）。我们分离了小鼠zfhi-4 cDNA，它长12 kb，能够编码3，550个氨基酸的蛋白质，含有4个同源结构域和22个锌指，包括两个假锌指基序。小鼠ZFH-4基因与小鼠ZFH-4基因有51%的同源性， 关于我们 小鼠ATBF 1。对成年小鼠组织中zfh-4转录本的RT-PCR分析表明，zfh-4在脑、心脏、肺和肌肉中可检测到表达。在这些小鼠组织中，ATBF 1转录本在扩增zfh-4转录本的条件下PCR扩增很差，表明zfh-4 mRNA的表达高于ATBF 1 mRNA的表达。我们研究了AFP基因的调节AFP产生胃癌的活性转录因子，肝细胞核因子1（HNF 1）和抑制性转录因子，ATBF 1。RNA酶保护实验表明，胃癌细胞中AFP的产生与HNF 1的表达没有直接关系。ATBF 1和AFP在胃癌细胞中的表达呈明显的负相关。CAT检测显示ATBF 1可直接抑制AFP基因的表达。临床标本的免疫组化显示AFP产生细胞缺乏ATBF 1免疫反应性。我们的数据表明，ATBF 1的缺乏是负责AFP基因在胃癌中的表达，和ATBF 1的缺乏是一个独特的特征AFP产生的胃癌，可能是重要的高度恶性性质。少

DNA/RNA-dependent ATPase activity is associated with ATBF1, a multiple homeodomain-zinc finger protein (Biochimica et Biophysica Acta). We examined whether ATPase activity is associated with the ATBF1 molecule. A 263-amino acid segment of the ATBF1 molecule, termed AHZ, which contains the ATPase A-motif, homeodomain IV and zinc finger 21, was expressed in E.coli as the form of GST fusion protein and analyzed for ATPase activity. We found that AHZ was able to hydorolyze ATP and had ability to bind both DNA and RNA. The ATPase activity associated with ATBF1 is DNA/RNA-dependent and unique in that it requires both homeodomain and zinc finger motifs.The mouse ZFH-4 protein contains four homeodomains and twenty-two zinc fingers (Biochem. Biophys. Res. Commun). We isolated the mouse zfhi-4 cDNA which is 12 kb long and capable of encoding a 3,550-amino acid protein containing four homeodomains and 22 zinc fingers including two pseudo zinc finger motifs. The mouse ZFH-4 is 51% homologous to th … More e mouse ATBF 1. RT-PCR analysis of zfh-4 transcripts in adult mouse tissues show that zfh-4 expression was detectable in brain, heart, lung and muscle. In these mouse tissues, ATBF1 transcripts were poorly amplified by PCR under the condtions where zfh-4 transcripts were amplified, suggesting that the expression of zfh-4 mRNA is higher than that ofATBF1 mRNA.Alpha-fetoprotein (AFP) producing gastric cancer lacks transcription factor ATBF 1 (Oncogene). We investigated AFP gene regulation in AFP-producing gastric cancer by an active transcription factor, hepatocyte nuclear factor 1 (HNF1) and a repressive transcription factor, ATBF1. Rnase protection assays revealed that the production of AFP in gastric cancer cells did not directly associate with HNF1 expression. An inverse relation between the expressions of ATBF1 and AFP was clearly observed in gastric cancer cells. CAT assays showed the direct inhibition of AFP gene expression by ATBF1. Immunohistochemistry of clinical samples revealed that AFP-producing cells lacked ATBF1 immunoreactivity. Our data suggests that the absence of ATBF1 is responsible for AFP gene expression in gastric cancer, and the absence of ATBF1 is a distinct characteristic of AFP-producing gastric cancer and might be important for its highly malignant nature. Less