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

本研究旨在阐明CAG重复序列扩增引起神经退行性疾病的分子机制。为了实现这一目标，两个战略！已就业; 1。人脑中表达的CAG重复序列cDNA的分子克隆，作为遗传性神经退行性疾病的候选基因。神经脱髓鞘机制的阐明：由编码多聚谷氨酰胺延伸的CAG重复序列引起。作为前一种方法，我们用（CAG）10或（CAG）20寡核苷酸探针筛选人脑cDNA文库。排除重叠克隆，我们已经确定了92个独立的cDNA克隆作为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> 10个CAG重复的cDNA克隆。这些cDNA克隆被认为是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功能障碍的机制，作为核运输和核内积累的突变蛋白携带扩大聚谷氨酰胺延伸的结果。我们进行了表达谱的Q129小鼠catfying全长突变体DRPEA基因携带一个大大扩展的GAG重复（129个重复单位），已在我们的实验室开发。详细的表达谱分析显示78个基因表达下调，16个基因表达上调。以时间依赖性方式观察表达水平的改变。许多cAMP反应基因被包括在dpwh调控基因中，证实了我们的假设，即CREB依赖的转录激活被扩展的多聚谷氨酰胺片段抑制。

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.