Development of targeted therapeutic agents for the treatment of FXTAS (2 of 6)

该联盟项目1下的研究将涉及进一步研究神经细胞模型 神经退行性疾病，脆性X相关震颤/共济失调综合征（FXTAS）。的发病机制 FXTAS是由前突变产生的过量FMR 1 RNA的毒性功能获得的直接结果 脆性X智力低下（FMR 1）基因的CGG重复扩增。这一目标的主要目的 该项目将确定和评估各种候选治疗药物， 病原性RNA的作用;通过反义DNA（阿索）或siRNA介导的敲低（目的1 和2）;通过神经病理过程的下游效应，如受损的谷氨酸 调节/摄取导致谷氨酸毒性（目的3）;或通过扩大的- CGG-重复RNA（目的4）。目的1和2将检验以下假设： 细胞模型或转基因小鼠模型（项目2），将至少部分逆转致病过程。 使用诱导型细胞模型的研究将检验这一假设，并与项目2一起，将对 在人类中的未来的基于阿托西肽的疗法。基于临床/病理学证据（项目1和3） FXTAS中明确的星形胶质细胞功能障碍，我们将测试我们的工作假设，即谷氨酸失调 作为这些研究的一个组成部分，我们将测试 美金刚在FXTAS的混合神经元/星形胶质细胞鼠细胞模型中，部分为 美金刚的临床试验 基于阿糖胞苷的治疗剂（阿索，siRNA）的开发将涉及两个重要的方面， 元素第一，系统地确定使用也可以瞄准核武器的反卫星防御系统的必要性 作为细胞质RNA，或者是否足以使用基于siRNA的靶向细胞质。第二、 与项目2一起，我们将开发非病毒、CNS靶向免疫脂质体递送方法， 在小鼠模型中体内递送候选阿索或siRNA寡核苷酸（项目2）。在此期间， 实验，并结合项目2，我们将研究致病的时间和可逆性， 反应;当考虑FXTAS治疗干预的时机时，这个问题很重要。 最后，连同项目2和项目4，我们将探讨发展问题的性质， 携带前突变等位基因的儿童，以确定是否如我们所怀疑的， 代表了由于RNA毒性引起的新的发育表型，代表了略低的 蛋白质水平将表征广泛的脆性X综合征谱效应，或反映组合 这两种致病机制。这最后一个问题提供了一个例子， 跨学科方法。

Research under Project 1 of the Consortium will involve further study of neural cell models of the neurodegenerative disorder, fragile X-associated tremor/ataxia syndrome (FXTAS). The pathogenesis of FXTAS is the direct result of a toxic gain-of-function of excess FMR1 RNA that is produced from premutation CGG-repeat expansions of the fragile X mental retardation (FMR1) gene. The principal objective of this project will be the identification and assessment of various candidate therapeutic agents that m.ight attenuate the effects of the pathogenic RNA; through antisense-DNA- (ASO) or siRNA-mediated knock-down (Aims 1 and 2); through downstream effects of the neuropathic process, such as impaired glutamate regulation/uptake leading to glutamate toxicity (Aim 3); or through more proximal effects of the expanded- CGG-repeat RNA (Aim 4). Aims 1 and 2 will test the hypothesis that elimination of the RNA, either in neural cell models or in transgenic mouse models (Project 2), will at least partially reverse the pathogenic process. Studies using inducible cell models will test this hypothesis and, with Project 2, will develop expectations for future oligonucleotide-based therapies in humans. Based on clinical/pathological evidence (Projects 1 and 3) of clear astrocyte dysfunction in FXTAS, we will test our working hypothesis that glutamate dysregulation contributes to the neurodegeneration in FXTAS, as one component of these studies, we will test the effect of memantine in mixed neuronal/astrocyte murine cell models of FXTAS, in part to provide a cellular basis for the clinical trial of memantine in Project 3. The development of oligonucleotide-based therapeutic agents (ASO, siRNA) will involve two important elements. First, a systematic determination of the necessity of using ASOs, which can target nuclear as well as cytoplasmic RNA, or whether it is sufficient to use siRNA-based targeting to the cytoplasm. Second, together with Project 2, we will develop non-viral, CNS-targeted immunoliposomal delivery methods to deliver candidate ASO or siRNA oligos in vivo in mouse models (Project 2). During the course of these experiments, and in conjunction with Project 2, we will examine the timing and reversibility of the pathogenic response; this issue is important when considering the timing of therapeutic intervention for FXTAS. Finally, together with Projects 2 and 4, we will investigate the nature of developmental problems in children who are carriers of premutation alleles, to determine whether, as we suspect, their involvement represents a novel developmental phenotype due to RNA toxicity, represents an effect of slightly lower protein levels that would characterize a broad fragile X syndrome spectrum effect, or reflects a combination of both pathogenic mechanisms. This last issue provides an example of the true power of the interdisciplinary approach.