Development of therapeutic strategies for Rett syndrome

Rett综合征是女性智力低下的最常见原因之一，是由MECP 2基因突变引起的。该基因编码DNA结合蛋白MeCP 2，其在基因表达的表观遗传控制中起关键作用。令人惊讶的是，在条件性Mecp 2敲除小鼠中显示Mecp 2的再表达可以逆转临床症状，表明Rett综合征是可治疗的病症。以前，我们已经产生并表征了一种小鼠模型，该模型携带在Rett综合征患者中最常见的MECP 2基因无义突变（p.R168X）。该研究项目的目的是开发Rett综合征的治疗策略，旨在重新表达或取代MeCP 2。无义突变的通读：我们以前已经表明，它是可能的，以诱导显着表达的MeCP 2在转染细胞和成纤维细胞从kockin小鼠通过处理与各种氨基糖苷类。然而，由于化合物的毒性和血脑屏障的低渗透性，体内实验迄今为止是不成功的。为了克服这些问题，我们将使用新的化合物，提高通读和测试合成氨基糖苷类药物已被改变，以允许更好地渗透血脑屏障。此外，我们将鞘内给予氨基糖苷类药物，从而避免全身毒性和血脑屏障。此外，我们打算用Ataluren（Translarna®）口服治疗小鼠，Ataluren是一种最近被批准用于Duchenne肌营养不良症的通读疗法的小分子。蛋白质替代疗法：第二种治疗方法旨在直接替代MeCP 2。由于MeCP 2不能进入细胞，产生融合蛋白，其中MeCP 2蛋白与人免疫缺陷病毒-1的蛋白转导结构域融合。为了绕过血脑屏障，将鞘内给予融合蛋白。骨髓移植：使用敲入小鼠模型，我们能够表明，除了以前报道的，骨髓移植不会导致雄性小鼠的生存期延长。由于Rett综合征是一种几乎只影响雌性的疾病，由于X失活，雌性在50%的细胞中表达正常的MECP 2等位基因，因此现在将在雌性小鼠中进行实验。

Rett syndrome, one of the most frequent causes of mental retardation in females, is caused by mutations in the MECP2 gene. The gene codes for the DNA binding protein MeCP2, which has a key role in the epigenetic control of gene expression. Surprisingly it was shown in conditional Mecp2 knockout mice that re-expression of Mecp2 can reverse the clinical symptoms indicating that Rett syndrome is a treatable disorder. Previously we have generated and characterized a mouse model that carries the nonsense mutation in the MECP2 gene most commonly found in patients with Rett syndrome (p.R168X). The aim of this research project is to develop therapeutic strategies for Rett syndrome that aim to re-express or replace MeCP2. Readthrough of nonsense mutations: We have shown previously that it is possible to induce significant expression of MeCP2 in transfected cells and in fibroblasts from the kockin mice by treatment with various aminoglycosides. Experiments in vivo, however, were so far unsuccessful due to the toxicity of the compounds and the low penetration of the blood brain barrier. To overcome these problems we will use novel compounds that enhance the readthrough and test synthetic aminoglycosides that have been altered to allow better penetration of the blood brain barrier. Moreover, we will administer the aminoglycosides intrathecally thereby circumventing the systemic toxicity and the blood brain barrier. Furthermore, we intend to treat the mice orally with Ataluren (Translarna®), a small molecule which was approved recently for readthrough therapy in Duchenne muscular dystrophy. Protein replacement therapy: The second therapeutic approach is aimed to replace MeCP2 directly. As MeCP2 cannot enter the cells a fusion protein was generated wherein the MeCP2 protein is fused to the protein transduction domain of the human immunodeficiency virus-1. To bypass the blood brain barrier the fusion protein will be given intrathecally. Bone marrow transplantation: Using the knockin mouse model we were able to show that other than previously reported, bone marrow transplantation does not lead to an extended survival in male mice. As Rett syndrome is a disorders that almost exclusively affects females, who due to the X-inactivation express a normal MECP2 allele in 50% of the cells, the experiments will now be carried out in female mice.