Rett syndrome (RTT) is a neurodevelopmental disorder primarily caused by mutations in Methyl-CpG-binding Protein 2 (MECP2). More than 35% of affected individuals have nonsense mutations in MECP2. For these individuals, nonsense suppression has been suggested as a possible therapeutic approach. To assess the viability of this strategy, we created and characterized a mouse model with the common p.R294X mutation introduced into the endogenous Mecp2 locus (Mecp2^R294X). Mecp2^R294X mice exhibit phenotypic abnormalities similar to those seen in complete null mouse models; however, these occur at a later time point consistent with the reduced phenotypic severity seen in affected individuals containing this specific mutation. The delayed onset of severe phenotypes is likely due to the presence of truncated MeCP2 in Mecp2^R294X mice. Supplying the MECP2 transgene in Mecp2^R294X mice rescued phenotypic abnormalities including early death and demonstrated that the presence of truncated MeCP2 in these mice does not interfere with wild-type MeCP2. In vitro treatment of a cell line derived from Mecp2^R294X mice with the nonsense suppression agent G418 resulted in full-length MeCP2 protein production, demonstrating feasibility of this therapeutic approach. Intraperitoneal administration of G418 in Mecp2^R294X mice was sufficient to elicit full-length MeCP2 protein expression in peripheral tissues. Finally, intracranial ventricular injection of G418 in Mecp2^R294X mice induced expression of full-length MeCP2 protein in the mouse brain. These experiments demonstrate that translational read-through drugs are able to suppress the Mecp2 p.R294X mutation in vivo and provide a proof of concept for future preclinical studies of nonsense suppression agents in RTT.

中文翻译：

---

R294X Mecp2 在新型雷特综合征小鼠模型中的药理学通读。

Rett 综合征 (RTT) 是一种神经发育障碍，主要由甲基-CpG结合蛋白 2 ( MECP2 )的突变引起。超过 35% 的受影响个体在MECP2中有无义突变。对于这些人，废话抑制已被建议作为一种可能的治疗方法。为了评估该策略的可行性，我们创建并表征了一种小鼠模型，该模型具有引入内源性Mecp2基因座 ( Mecp2 ^R294X )的常见 p.R294X 突变。Mecp2 ^R294X小鼠表现出与完全无效小鼠模型相似的表型异常；然而，这些发生在较晚的时间点，与在包含这种特定突变的受影响个体中观察到的表型严重程度降低一致。严重表型的延迟发作可能是由于Mecp2 ^R294X小鼠中存在截短的 MeCP2 。在Mecp2 ^R294X小鼠中提供MECP2转基因可挽救包括早死在内的表型异常，并证明这些小鼠中截短的 MeCP2 的存在不会干扰野生型 MeCP2。在体外处理的细胞系的衍生自的Mecp2 ^R294X带有无义抑制剂 G418 的小鼠产生了全长的 MeCP2 蛋白，证明了这种治疗方法的可行性。在Mecp2 ^R294X小鼠中腹腔注射 G418足以引起外周组织中全长的 MeCP2 蛋白表达。最后，在Mecp2 ^R294X小鼠中颅内脑室注射 G418诱导小鼠大脑中全长 MeCP2 蛋白的表达。这些实验表明，翻译通读药物能够在体内抑制Mecp2 p.R294X 突变，并为未来 RTT 中无义抑制剂的临床前研究提供概念证明。