Elucidation of molecular mechanisms of neurodegenerative diseases caused by expansion of CAG repeats

本研究旨在阐明由CAG重复序列扩增引起的泌尿消化系统疾病的分子机制。要实现这一目标，有两个策略！已受雇；1. 1 .作为遗传性神经退行性疾病候选基因的人脑CAG重复序列cdna的分子克隆；神经退行性变性的机制探讨CAG重复编码聚戊二氨酸片段。作为前一种方法，我们使用（CAG）10或（CAG）20寡核苷酸探针筛选人脑cDNA文库。排除重叠克隆，我们鉴定出92个独立的cDNA克隆为CAG重复序列的cDNA克隆。在92个克隆中，我们选择了41个克隆作为携带bbb10cag重复序列的CDNA克隆。这些cDNA克隆被筛选为遗传性神经退行性疾病的候选基因。作为后一种方法，我们的研究重点是阐明核运输和携带扩大的聚谷氨酰胺延伸的突变蛋白的核内积累导致核功能障碍的机制。我们对Q129小鼠进行了表达谱分析，分类了一个全长突变的DRPEA基因，该基因携带一个在我们实验室开发的大量扩增的GAG重复序列（129个重复单元）。详细的表达谱分析显示78个下调基因和16个上调基因。表达水平的改变是随时间变化的。许多camp反应性基因被包括在dpwh调节基因中，证实了我们的假设，即creb依赖性转录激活被扩大的聚谷氨酰胺拉伸抑制。

This study was aimed to elucidate molecular mechanisms ofheurodegetterative diseases caused by expansion of CAG repeats. To accomplish this aim, two strategies! have been employed; 1. Molecular cloning of CAG repeat-containing cDNAs expressed in human brains as the candidate genes for hereditary neurodegenerative diseases, and 2. Elucidation of mechanisms of neurodegeherati6n : caused by expahded; CAG repeats coding for polyglutarnine stretches. As the former approach, we screened human brain cDNA libraries using (CAG)10 or (CAG)20 oligbnucleotide probes. Excluding overlapping clones, we have identified 92 independent cDNA clones as the CAG repeat-containing CDNA clones. Among the 92 clones, we selected 41 clones as the CDNA clones carrying > 10 CAG repeats. These cDNA clones are beihg screeried as the candfdate genes for hereditary neurddegenerative disease. As the latter approach, we focused our study to elucidate the mechanisms of nuclear dysfunctions as a result of nuclear transport and intranuclear accumulation of mutant protein carrying expanded polyglutamine stretches. We performed expression pro filing of Q129 mice catfying a full-length mutant DRPEA gene carrying a largely expanded GAG repeat (129 repeat units) that have been developed in our laboratory. Detailed expression pro filing analysis revealed 78 down-regulated genes and 16 up-regulated genes. The alteration of expression levels is observed as a time-dependent manner. Many cAMP-resporisive genes were included in the dpwh-regulated genes, confirming our hypothesis that CREB-dependent transcriptional activation is suppressed by expanded polyglutamine stretches.