Chromatin remodeling in transgenic mouse models of HD

亨廷顿氏病是一种常染色体显性神经退行性疾病，目前尚无有效的治疗方法。虽然已经提出了许多致病机制，但转录失调已成为一个潜在的关键方面。在HD转基因小鼠模型中，已经描述了mRNA稳态水平的许多变化。然而，mRNA扰动的机制尚不明确。阐明这些机制将对理解和发展HD的未来治疗具有重要意义。在真核生物中，基因表达是通过染色质的修饰和与特定转录因子的关联来调节的。虽然转基因HD小鼠（R6/2）大脑稳态mRNA水平的改变是转录失调的事实证据，但染色质结构是否存在特异性改变尚不清楚。在本项目中，我们将探索转基因HD小鼠模型中的染色质重塑。首先，我们将确定米霉素（一种与富含gc的DNA区域结合的金黄色抗生素，已被证明可以延长R6/2小鼠的寿命）是否能纠正mRNA表达异常

Huntington's disease is an autosomal dominant neurodegenerative disease for which there is currently no effective treatment. Although a number of pathogenic mechanisms have been proposed, transcriptional dysregulation has emerged as a potential critical aspect. In transgenic mouse models of HD, numerous alterations in the steady state levels of mRNA have been described. However, the mechanisms underlying mRNA perturbation are undefined. Elucidation of such mechanisms will have significant relevance to the understanding and development of future treatment of HD. In eukaryotes, gene expression is regulated through modification of chromatin and association with specific transcription factors. While alteration of steady state mRNA levels in transgenic HD mouse (R6/2) brain is de facto evidence of transcriptional dysregulation, it is yet unknown whether there are specific alterations in chromatin structure. In this project, we will explore chromatin remodeling in a transgenic HD mouse model. First, we will determine if mithramycin--an aureolic antibiotic that binds to GC-rich regions of DNA and which has been shown to extend lifespan in R6/2 mice--corrects mRNA expression abnormalities that we have previously described in these mice. We will use receptor binding autoradiography and in situ hybridization to perform these analyses. Next, we will seek to determine the role of a fatnily of transcription factors, the Sp family, with a set of genes whose expression is known to be altered in R6/2 mice. We will explore the interactions of Sp and related zinc finger transcription factors by using Chromatin ImmunoPrecipitation (CHIP) assays with real-time PCR detection. Finally, we will explore the ability of mithramycin to reverse chromatin abnormalities in the R6/2 mice. Taken together, these experiments will elucidate the molecular mechanisms underlying transcriptional dysregulation in a model of Huntington's disease. Such elucidation of a central pathogenic mechanism will open the way towards rational, mechanism-targeted therapy for this devastating disease.