Analysis on interaction between triplet repeat disease gene products and neuron-specific transcription-related factors

利用酵母双杂交技术筛选人胚胎cDNA文库，克隆了多聚谷氨酰胺结合蛋白。我们获得了6个以上的克隆，它们都编码富含极性氨基酸的序列。因此，我们推测富含极性氨基酸的序列可以通过氢键与多聚谷氨酰胺束结合。接下来，我们分析了编码命名为PQBP-1的新基因的克隆之一。该蛋白含有参与蛋白质相互作用的WWP结构域和由七氨基酸和二氨基酸重复序列组成的富含极性氨基酸的序列。后一区域被认为是多聚谷氨酰胺束的结合结构域。我们发现，PQBP-1结合到三联重复疾病基因产物和转录相关因子的多聚谷氨酰胺。PQBP-1作为负转录调节因子。它主要位于细胞核中。在组织中，其表达在小脑皮质中最高。通过这些观察，我们正在研究PQBP-1在三联体重复序列疾病发病机制中的作用。我们还利用这一支持研究了早老素-1的作用，发现早老素-1调节c-Jun同源二聚体功能。有了这项资助，我们还发现AP-2 β抑制D1 A多巴胺受体基因的表达。

We have cloned binding proteins to the polyglutamine tract by screening human embryonic cDNA library with yeast two-hybrid method. We obtained more than 6 clones and all of them encoded polar amino acid-rich sequences. Therefore, we suspected that polar amino acid-rich sequences can bind to the polyglutamine tract via hydrogen bond. Next, we analyzed one of the clone encoding a new gene designated as PQBP-1. This protein contains WWP domain which is participated in protein-protein interaction and polar amino acid-rich sequences composed of hepta- and di-amino acid repeats. The latter region was considered to be the binding domain to the polyglutamine tract. We showed that PQBP-1 binds to the polyglutamine of both triplet repeat disease gene products and transcription-related factors. PQBP-1 acts as a negative transcriptional regulator. It is located mainly in the nucleus. Among tissues, its expression was highest in the cortex of the cerebellum. From these observations, we are investigating the role of PQBP-1 in the pathogenesis of triplet repeat disorders.We have also used this support for the research on the role of presenilin-1 and found that presenilin-1 modulates c-Jun homodimer function. With this grant, we also found that AP-2 beta suppresses D1A dopamine receptor gene expression.