RECEPTOR GENE TRANSCRIPTION IN HUNTINGTON'S DISEASE

描述(申请人提供)：亨廷顿病是一种进行性神经退行性疾病，目前还没有有效的治疗方法。转录失调被认为是亨廷顿病(HD)和其他聚谷氨酰胺疾病的重要发病机制。MRNA群的改变，包括那些编码神经递质受体的基因，是HD小鼠和细胞模型以及人类HD的一个标志。虽然许多研究已经证实，在HD模型中，mRNA群体发生了变化，但这种变化背后的机制仍然不清楚。包括特异性蛋白1(Sp1)在内的转录因子参与了HD的发病过程，但Sp1功能改变在导致mRNA改变中的作用尚未得到回答。在这一应用中，我们利用一组描述良好的基因变化--那些发生在神经递质受体中的基因--作为确定转录失调的分子机制的起点。我们提出了一系列假说，这些假说将对改变信使核糖核酸群体和导致疾病发病机制的过程产生关键的机制洞察。具体目标1将检验这样的假设，即突变的Huntingtin选择性地改变Sp1与HD下调基因启动子的关联。染色质免疫沉淀(ChIP)分析将评估Sp1基因在细胞、小鼠和人类HD组织中的结合程度。特殊目的2将验证Sp1与选定基因启动子结合减少会导致HD表型的假设。将通过RNA干扰、显性负结构和过度表达来操纵SP1的水平，并将评估这些操纵对mRNA和细胞毒性的影响。特异性目标3验证了亨廷顿蛋白对Sp 1功能的干扰会导致组蛋白异常修饰的假设。组蛋白修饰将在HD的小鼠和细胞模型中进行检查。综上所述，这些拟议的实验将系统地解决突变亨廷顿蛋白潜在损害的几个关键分子位点。这些基本的机制信息对于最终开发有效的HD治疗方法至关重要。

DESCRIPTION (provided by applicant): Huntington's disease is a progressive neurodegenerative disease for which no effective treatment exists. Transcriptional dysregulation is now considered to be an important mechanism in the pathogenesis of Huntington's disease (HD) and other polyglutamine diseases. Alteration of mRNA populations, including those encoding for neurotransmitter receptors, is a hallmark of murine and cellular models of HD as well as human HD. Although numerous studies have confirmed that mRNA populations are altered in HD models, the mechanism underlying such changes remains unknown. Transcription factors, including specificity protein 1 (Sp1), have been implicated in HD pathogenesis, but the role of altered Sp1 function in producing mRNA alterations has not been answered. In this application, we take advantage of a well-described set of gene alterations--those occurring in neurotransmitter receptors--as a starting point for determining the molecular mechanisms of transcriptional dysregulation. We propose a series of hypotheses that will yield critical mechanistic insight into the processes that alter mRNA populations and cause disease pathogenesis. Specific Aim 1 will test the hypothesis that mutant huntingtin selectively alters the association of Sp1 with the promoters of genes that are downregulated in HD. Chromatin Immunoprecipitation (CHIP) assays will assess the degree of Sp1-gene binding in cellular, murine and human HD tissues. Specific Aim 2 will test the hypothesis that decreased Sp1 binding to selected gene promoters causes HD phenotypes. Sp1 levels will be manipulated through RNA interference, dominant negative constructs and overexpression, and the effects of these manipulations on mRNA and cellular toxicity will be assessed. Specific Aim 3 tests the hypothesis that interference in Sp 1 function by huntingtin causes abnormal histone modification. Histone modifications will be examined in mouse and cell models of HD. Taken together, these proposed experiments will systematically address several key molecular loci of potential damage by mutant huntingtin. Such fundamental mechanistic information is critical to the eventual development of effective therapy for HD.