Pathogenic mechanisms of C9orf72 GGGGCC repeat expansions in amyotrophic lateral sclerosis and frontotemporaldementia and development of therapeutic strategies

C9orf72 GGGGCC重复扩增在肌萎缩侧索硬化症和额颞叶痴呆中的致病机制及治疗策略的开发

• 批准号: 8835911
• 负责人: Jie Jiang
• 金额: $ 5.33万
• 依托单位: LUDWIG INSTITUTE FOR CANCER RES LTD
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-12-01 至 2015-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8835911
• 关键词: A Mouse; Alleles; Amyotrophic Lateral Sclerosis; Antisense Oligonucleotides; Brain region; C9ORF72; Clinical Trials; Development; Dipeptides; Disease; Frontotemporal Dementia; Functional RNA; Genes; Genetic; Genetic Transcription; High-Throughput Nucleotide Sequencing; Human; Individual; Infusion procedures; Length; Mediating; Messenger RNA; Mus; Nerve Degeneration; Neurodegenerative Disorders; Pathogenesis; Pathologic; Pathology; Patients; Pattern; Phenotype; Production; RNA; RNA Processing; RNA Splicing; RNA-Binding Proteins; Spinal Cord; Testing; Therapeutic; Tissues; Toxic effect; Transgenes; Transgenic Mice; Translations; age related; efficacy testing; gain of function; loss of function; mouse model; polypeptide; protein B; public health relevance; therapeutic development

DESCRIPTION (provided by applicant): Expanded GGGGCC hexanucleotide repeats in a non-coding region of the C9orf72 gene were recently identified as the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), two neurodegenerative conditions with genetic and pathological overlap. The pathogenic mechanisms of this expansion are not understood, but initial observations point to either a loss of function of the endogenous C9orf72 gene, and/or a toxic gain of function of the expanded RNA, mediated either by sequestration of RNA binding proteins or by production of aberrant polypeptide(s) through repeat-associated non-ATG-dependent (RAN) translation. Here, I propose to use genetically modified mouse models to determine contribution of RNA-mediated gain of toxicity and/or C9orf72 loss of function to ALS/FTD pathogenesis caused by C9orf72 repeat expansions and to develop therapeutic strategies. I have already established multiple lines of BAC transgenic mice expressing a repeat-containing human C9orf72 gene with different repeat lengths and expression levels, including ones with a similar RNA level but with hexanucleotide repeats between ~100 and ~450, and those that have ~450 repeats with a 4-fold range of RNA expression. I have also documented abnormal, pathologic RNA foci containing both sense and antisense repeat RNAs in several brain regions and spinal cords of all transgenic mice tested so far (4 lines), similar to what have been observed in human C9orf72 patients, supporting that ALS/FTD pathogenesis is driven, at least in part, by RNA-mediated gain of toxicity. In Aim 1A & 1B, I will determine if any age-dependent pathology (RNA foci or repeat-associated non-ATG (RAN) translation), RNA signature change and/or phenotype is developed in C9orf72 repeat expressing transgenic mice and if such pathology/phenotype is repeat length and/or expression dependent. Recognizing that a contribution of C9orf72 haploinsufficiency to ALS and FTD pathogenesis is supported by reduced C9orf72 mRNAs in tissues from C9orf72-ALS/FTD patients, I will determine the consequence (if any) of diminished C9orf72 expression in mice with a disrupted C9orf72 allele and if the transgene-dependent ALS/FTD related phenotype is exacerbated by C9orf72 loss of function (Aim 1C). Finally, I will use transgenic mice to identify antisense oligonucleotides (ASOs) that mediate degradation of C9orf72 RNAs carrying repeat expansions in an effort to develop a therapeutic approach to diminish the consequences of any toxic gain of function (Aim 2). I believe that the combination of Aims 1 and 2 that I propose here have substantial promise to identify disease mechanism from hexanucleotide expansion in C9orf72 and facilitate development of ASO infusion therapy as an approach for human clinical trial.

描述（由申请人提供）：在C9ORF72基因的非编码区域中扩展的GGGGCC六核苷酸重复序列，最近被确定为肌萎缩性侧面硬化症（ALS）（ALS）和额外痴呆症（FTD），两种神经变性条件的最常见遗传学原因，两种神经降解疾病。该扩展的致病机制尚不清楚，但是初始观察表明，内源性C9ORF72基因的功能丧失和/或/或/或/或通过隔离RNA结合蛋白的介导的功能的毒性获得，或通过异常多肽的产生通过重复搭接的非 - At-ATG依赖性（SAN）依赖（SAN）介导的（s）。 在这里，我建议使用转基因的小鼠模型来确定RNA介导的毒性增益和/或C9ORF72功能丧失对ALS/FTD发病机理，由C9ORF72重复膨胀引起的ALS/FTD发病机理，并制定治疗策略。我已经建立了多个表达重复的人C9orf72基因的BAC转基因小鼠，具有不同的重复长度和表达水平，其中包括具有相似的RNA水平但六核苷酸重复量〜100至〜450之间，并且具有〜450重复率为4倍的RNA表达的BAC核苷酸重复。我还记录了迄今为止在几个大脑区域和所有经过测试的转基因小鼠（4行）中的多个大脑区域和脊髓中含有感官和反义重复RNA的异常，与人类C9ORF72患者观察到的相似，这与ALS/FTD病原体相似，至少在ALS/FTD病原体中受到驱动，至少是由RNA MIDIAD SIDISS ID SID SID SID SID SID SID SID SID SID SID SID SID SID SID SID SIDISS ID SID SIDIST ID SID SID SID SID SID SID SID SID SID SID SID ID选择为毒素。在AIM 1A和1B中，我将确定是否依赖年龄的病理（RNA焦点或重复相关的非ATG（RAN）翻译），RNA签名变化和/或表型在C9ORF72重复表达转基因小鼠中以及这种病理学/表型/表型是否重复和/或表达。认识到C9ORF72对ALS和FTD发病机理的贡献受到C9orf72-ALS/FTD患者的组织中C9orf72 mRNA的降低支持，我将确定C9orf72在小鼠中的C9orf72表达的后果（如果有任何相关的C9orf72 Allers fertent and ft and fttent）的后果（即C9ORF72功能丧失（AIM 1C）会加剧。最后，我将使用转基因小鼠识别介导携带重复扩张的C9orf72 RNA降解的反义寡核苷酸（ASO），以开发一种治疗方法，以减少任何功能毒性增益的后果（AIM 2）。 我认为，我在这里提出的目标1和2的组合具有实质性的承诺，可以从C9ORF72中的六核苷酸扩展中鉴定疾病机制，并促进ASO输液疗法的发展作为人类临床试验的方法。