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

DNA/ rna依赖性atp酶活性与ATBF1相关，ATBF1是一种多同源结构域锌指蛋白（biochemica et Biophysica Acta）。我们研究了ATPase活性是否与ATBF1分子相关。ATBF1分子中含有atp酶A基序、同源结构域IV和锌指21的263个氨基酸片段被称为AHZ，以GST融合蛋白的形式在大肠杆菌中表达，并分析了atp酶活性。我们发现AHZ能够水解ATP，并且能够结合DNA和RNA。与ATBF1相关的atp酶活性是DNA/ rna依赖的，其独特之处在于它需要同源结构域和锌指基序。小鼠ZFH-4蛋白含有4个同源结构域和22个锌指。Biophys。Commun》)。我们分离了小鼠zfhi-4 cDNA，该cDNA长12 kb，能够编码一个含有4个同源结构域和22个锌指（包括两个伪锌指基序）的3550个氨基酸的蛋白。小鼠ZFH-4与ATBF - 1有51%的同源性。对成年小鼠组织中zfh-4转录本的RT-PCR分析显示，zfh-4在脑、心、肺和肌肉中均有表达。在这些小鼠组织中，在zfh-4转录本扩增的条件下，通过PCR扩增ATBF1转录本的效果较差，说明zfh-4 mRNA的表达高于ATBF1 mRNA的表达。产生甲胎蛋白（AFP）的胃癌缺乏转录因子ATBF - 1（癌基因）。我们研究了AFP基因通过活性转录因子肝细胞核因子1 （HNF1）和抑制转录因子ATBF1在AFP产生胃癌中的调控作用。Rnase保护实验显示，胃癌细胞中AFP的产生与HNF1的表达不直接相关。胃癌细胞中ATBF1与AFP的表达呈明显的负相关。CAT检测显示ATBF1直接抑制AFP基因表达。临床样本的免疫组化显示，产生afp的细胞缺乏ATBF1免疫反应性。我们的数据表明，ATBF1的缺失与胃癌中AFP基因的表达有关，而ATBF1的缺失是产生AFP的胃癌的一个明显特征，可能是其高度恶性性质的重要原因。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