Endo-lysosomal mechanisms and treatment in atypical cerebellar neurodevelopment

非典型小脑神经发育的内溶酶体机制和治疗

• 批准号: 9380297
• 负责人: Matthew F. Pescosolido
• 金额: $ 4.4万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9380297
• 关键词: Abnormal Cell; Address; Animal Model; Ataxia; Atrophic; Autistic Disorder; Autophagocytosis; Autophagosome; Brain Diseases; Brain-Derived Neurotrophic Factor; Cerebellar Diseases; Clinical Trials; Defect; Development; Disease; Electron Microscopy; Endosomes; Exhibits; FDA approved; FRAP1 gene; Foundations; Functional disorder; Future; Goals; Hereditary Disease; Hippocampus (Brain); Immunohistochemistry; In Vitro; Insulin-Like Growth Factor I; Intellectual functioning disability; Investigation; Knockout Mice; Lead; Link; Lysosomal Storage Diseases; Measures; Medicine; Membrane; Morbidity - disease rate; Motor; Mus; Mutant Strains Mice; Mutation; Nerve Degeneration; Neurons; Pathology; Pharmaceutical Preparations; Proteins; Purkinje Cells; Recurrence; Research; Role; Signal Transduction; Sirolimus; Slice; Symptoms; Syndrome; Techniques; Testing; Therapeutic; Treatment Efficacy; Tuberous Sclerosis; X-linked intellectual disability; cost; efficacy testing; experimental study; genetic pedigree; human disease; in vivo; male; motor disorder; mouse model; mutant; nervous system disorder; neurodevelopment; neurogenetics; new therapeutic target; novel; novel therapeutics; targeted therapy trials; targeted treatment; treatment strategy

PROJECT SUMMARY Christianson syndrome (CS) is a monogenic, X-linked neurologic disorder caused by changes in the Na+/H+ exchanger 6 (NHE6) that provides an opportunity to study both neurodevelopment and neurodegeneration (Gilfillan et al 2008). It is one of the most common X-linked disorders (Tarpey et al. 2009) and is notable for cerebellar pathology such as Purkinje cell loss (Garbern et al. 2010, Christianson et al. 1999) and cerebellar atrophy (Pescosolido et al. 2014). How NHE6 mutations cause cerebellar-associated pathology is unknown. By identifying the cellular mechanism underlying abnormal cerebellar development, novel therapeutic agents targeting progressive cerebellar symptoms can be tested. Our preliminary evidence recapitulates progressive Purkinje cell loss in NHE6 mutant mice, and motor dysfunction has been identified in these mice (Stromme et al. 2011, Sikora et al. 2015). Our previous research has shown loss of NHE6 results in endosomal overacidification, which leads to decreased neuronal arborization and BDNF signaling (Ouyang et al. 2013). Furthermore, a CS mouse model has shown to have deficits in endosomal-lysosomal functioning (Stromme et al. 2011), suggesting autophagy dysfunction as a potential mechanism in NHE6 mutations. Purkinje cell degeneration can be caused by autophagy deficits (Hara et al. 2006). Therefore, we hypothesize that NHE6 mutations cause endosomal overacidification and enhanced autophagy resulting in Purkinje cell that leads to abnormal cerebellar development and degeneration. We will also test the hypothesis these defects may be reversed by IGF-1 treatment in vitro and in vivo in our mouse model. We will address these hypotheses through the following Specific Aims. In the first aim we will demonstrate that an over-abundance of low pH endo-membranes in NHE6 mutant Purkinje cells is associated with abnormal Purkinje cell development that can be rescued or worsened by drugs in vitro. In the second aim we will elucidate a mechanism involving enhanced autophagy and decreased mTOR activity in NHE6-null Purkinje cells in vitro and in vivo that may be reversed by IGF-1 treatment. We will also examine whether IGF-1 treatment may ameliorate motor coordination deficits in NHE6 mutant mice. We will utilize cerebellar slices from an NHE6 null male mouse model to examine endo-lysosomal membranes, Purkinje cell development, autophagy, mTOR activity and IGF treatment. The information obtained from this project will provide a mechanistic understanding of cerebellar pathology in Christianson syndrome and, possibly, other neurologic disorders with cerebellar-related symptoms. Furthermore, this research may identify an FDA-approved drug, IGF, as a potential therapeutic for neurologic disorders with cerebellar dysfunction.

项目概要 克里斯蒂安森综合征 (CS) 是一种单基因 X 连锁神经系统疾病，由 Na+/H+ 交换器 6 (NHE6) 提供了研究神经发育和 神经退行性疾病（Gilfillan 等，2008）。它是最常见的 X 连锁疾病之一（Tarpey 等人，2009） 并以浦肯野细胞丢失等小脑病理学而闻名（Garbern 等人，2010 年；Christianson 等人，1999 年） 和小脑萎缩（Pescosolido 等，2014）。 NHE6 突变如何导致小脑相关病理 未知。通过确定小脑发育异常的细胞机制，新颖的 可以测试针对进行性小脑症状的治疗药物。我们的初步证据 概括了 NHE6 突变小鼠进行性浦肯野细胞丧失，并且在 这些小鼠（Stromme 等人，2011 年；Sikora 等人，2015 年）。我们之前的研究表明 NHE6 结果丢失 内体过度酸化，导致神经元树枝化和 BDNF 信号传导减少（Ouyang 等 等人。 2013）。此外，CS 小鼠模型显示内体溶酶体功能存在缺陷 (Stromme et al. 2011)，表明自噬功能障碍是 NHE6 突变的潜在机制。 浦肯野细胞变性可能是由自噬缺陷引起的（Hara et al. 2006）。因此，我们假设 NHE6 突变导致内体过度酸化和自噬增强，导致浦肯野细胞 导致小脑发育异常和退化。我们还将检验这些缺陷的假设 在我们的小鼠模型中，体外和体内的 IGF-1 治疗可能会逆转这种情况。我们将解决这些 通过以下具体目标提出假设。在第一个目标中，我们将证明过多的 NHE6 突变型浦肯野细胞中的低 pH 内膜与异常浦肯野细胞发育有关 可以通过体外药物来挽救或恶化。在第二个目标中，我们将阐明一个机制，涉及 NHE6 缺失浦肯野细胞在体外和体内的自噬增强和 mTOR 活性降低可能是 IGF-1治疗可逆转。我们还将检查 IGF-1 治疗是否可以改善运动能力 NHE6 突变小鼠的协调缺陷。我们将利用 NHE6 缺失雄性小鼠的小脑切片 检查内溶酶体膜、浦肯野细胞发育、自噬、mTOR 活性和 IGF 的模型 治疗。从该项目获得的信息将提供对小脑的机械理解 克里斯蒂安森综合征的病理学，以及可能与小脑相关的其他神经系统疾病 症状。此外，这项研究可能会确定 FDA 批准的药物 IGF 作为潜在的治疗药物 伴有小脑功能障碍的神经系统疾病。