MECHANISMS OF RNA-MEDIATED CNS PATHOGENESIS IN MYOTONIC DYSTOPHY

强直性肌营养不良(DM)属于肌营养不良症，是一种对中枢神经系统(CNS)功能有显著影响的进行性多系统疾病。这些中枢神经系统的表现包括先天性糖尿病的智力低下和自闭症行为，以及睡眠过多，成人发病形式的执行功能障碍和皮质萎缩。对糖尿病分子基础的研究揭示了一种新的疾病机制，即RNA介导的发病机制，涉及两个无关基因中微卫星C(C)TG重复序列的扩增和有毒C(C)UG扩展RNA的合成。这些致病RNA干扰CELF和MBNL蛋白的正常选择性剪接功能，导致成人组织中胎儿亚型的持续存在或回复。为了确定这种RNA介导的疾病模型是否与DM的中枢神经系统功能障碍有关，我们最近培育了Mbnl2基因敲除小鼠，它们概括了DM大脑的特征病理特征，包括异常的REM睡眠倾向和空间记忆缺陷。在这项提议中，我们将首先通过证明MBNL2从其正常RNA靶向C(C)UG重复序列的转移在DM大脑中发生，来检验MBNL2对DM相关中枢神经系统发病机制的隔离假说。接下来，我们将确定Mbnl2基因敲除小鼠是否模拟了糖尿病中枢神经系统的全部特征，并将特定的错接事件与特定的疾病表现联系起来。最后，我们将检验MBNL基因之间的相互作用在先天性疾病中被破坏的假设。这些研究将为未来的疾病机制研究和针对DM大脑的治疗方法的开发提供新的成人起病和先天性DM的动物模型。

While myotonic dystrophy (DM) is classified as a muscular dystrophy, it is a progressive multi-systemic disease that has significant effects on central nervous system (CNS) function. These CNS manifestations include mental retardation and autistic behaviors in congenital DM and hypersomnia, executive dysfunction and cortical atrophy in the adult-onset form. Studies on the molecular basis of DM have revealed a novel disease mechanism, RNA-mediated pathogenesis, that involves the expansion of microsatellite C(C)TG repeats in two unrelated genes and the synthesis of toxic C(C)UG expansion RNAs. These pathogenic RNAs interfere with the normal alternative splicing functions of the CELF and MBNL proteins resulting in the persistence of, or reversion to, fetal isoforms in adult tissues. To determine if this RNA-mediated disease model is relevant to CNS dysfunction in DM, we have recently generated Mbnl2 knockout mice which recapitulate characteristic pathological features of the DM brain including abnormal REM sleep propensity and spatial memory deficits. In this proposal, we will first test the MBNL2 sequestration hypothesis for DM relevant CNS pathogenesis by demonstrating that transfer of MBNL2 from its normal RNA targets to C(C)UG repeats occurs in the DM brain. Next, we will determine if Mbnl2 knockout mice model the full range of DM CNS features and link specific mis-splicing events to characteristic disease manifestations. Finally, we will test the hypothesis that interactions between MBNL genes are disrupted in the congenital disease. These studies will provide novel animal models of adult-onset and congenital DM for future disease mechanism studies and the development of therapies that target the DM brain.