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

该联盟的项目1下的研究将涉及进一步研究大鼠的神经细胞模型。 神经退行性疾病，脆性X相关震颤/共济失调综合征(FXTAS)。黄斑狼疮的发病机制 FXTAS是由前突变产生的过量FMR1 RNA的毒性功能增强的直接结果 脆性X智力低下(FMR1)基因CGG重复扩增这样做的主要目的是 项目将是识别和评估各种可能减重的候选治疗剂。 致病RNA的作用；通过反义DNA-(ASO)或siRNA介导的击倒(目标1 和2)；通过神经病理过程的下游效应，如谷氨酸受损 调节/摄取导致谷氨酸毒性(目标3)；或通过扩大- CGG-Repeat RNA(目的4)。目标1和目标2将检验这样的假设，即在神经中消除RNA 在细胞模型或转基因小鼠模型(项目2)中，至少将部分逆转致病过程。 使用可诱导细胞模型的研究将检验这一假设，并将通过项目2开发对 未来以寡核苷酸为基础的人类疗法。基于临床/病理证据(项目1和3) 对于FXTAS中明显的星形胶质细胞功能障碍，我们将检验我们的工作假设，即谷氨酸失调 导致FXTAS的神经变性，作为这些研究的组成部分，我们将测试 美金刚在FXTAS混合神经元/星形胶质细胞小鼠细胞模型中的作用，部分是为了提供细胞基础 美金刚在项目3的临床试验。 基于寡核苷酸的治疗剂(ASO、siRNA)的开发将涉及两个重要的 元素。首先，系统地确定使用ASO的必要性，ASO也可以针对核 作为细胞质的RNA，或者使用基于siRNA的靶向细胞质是否足够。第二, 与项目2一起，我们将开发非病毒、中枢神经系统靶向免疫脂质体递送方法，以 在小鼠模型中体内传递候选ASO或siRNA寡核苷酸(项目2)。在这个过程中 实验，并结合项目2，我们将检查致病的时间和可逆性 反应：在考虑FXTAS的治疗干预时机时，这个问题很重要。 最后，我们将与项目2和4一起调查#年发展问题的性质。 是前突变等位基因携带者的儿童，以确定他们是否如我们怀疑的那样参与 代表了一种由于RNA毒性而产生的新的发育表型，代表了一种略低的效应 蛋白质水平将表征广泛的脆性X综合征谱系效应，或反映一种组合 这两种致病机制。最后一期提供了一个例子，说明了 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.