RECEPTOR GENE TRANSCRIPTION IN HUNTINGTON'S DISEASE

描述（由申请人提供）：亨廷顿病是一种进行性神经退行性疾病，目前尚无有效治疗方法。目前认为转录调控异常是亨廷顿病（Huntington 'sdisease，HD）和其他多聚谷氨酰胺疾病的重要发病机制。mRNA群体（包括编码神经递质受体的mRNA群体）的改变是HD以及人HD的鼠和细胞模型的标志。尽管许多研究已经证实，mRNA群体在HD模型中发生了改变，但这种变化的机制仍然未知。转录因子，包括特异性蛋白1（Sp1），已被牵连在HD发病机制，但在产生mRNA的变化改变Sp1功能的作用还没有得到回答。在这个应用中，我们利用一组描述良好的基因改变-发生在神经递质受体-作为确定转录失调的分子机制的起点。我们提出了一系列的假设，将产生关键的机制洞察的过程中，改变mRNA的群体和导致疾病的发病机制。具体目标1将测试的假设，突变亨廷顿蛋白选择性地改变协会的Sp1与基因的启动子，在HD下调。染色质免疫沉淀（CHIP）试验将评估细胞、鼠和人HD组织中Sp1基因结合的程度。具体目标2将检验Sp1与选定基因启动子结合减少导致HD表型的假设。Sp1水平将通过RNA干扰、显性阴性构建体和过表达进行操作，并将评估这些操作对mRNA和细胞毒性的影响。特异性目的3检验了亨廷顿蛋白对Sp 1功能的干扰导致组蛋白修饰异常的假设。将在HD的小鼠和细胞模型中检查组蛋白修饰。总之，这些拟议的实验将系统地解决几个关键的潜在损害的突变亨廷顿蛋白的分子位点。这些基本的机制信息对于最终开发HD的有效疗法至关重要。

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.