Pathogenic Mechanism of Spinocerebellar Ataxia Type 10

脊髓小脑共济失调10型发病机制

• 批准号: 7103348
• 负责人: TETSUO ASHIZAWA
• 金额: $ 33.98万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7103348
• 关键词: RNase protection assay; alleles; antisense nucleic acid; autosomal dominant trait; cerebellar ataxia /dyskinesia; clinical research; complementary DNA; gene mutation; genetic counseling; genetic markers; genetic transcription; human subject; immunocytochemistry; immunoprecipitation; introns; messenger RNA; molecular pathology; nervous system disorder epidemiology; neurogenetics; northern blottings; nucleic acid repetitive sequence; polymerase chain reaction; racial /ethnic difference; western blottings

DESCRIPTION (provided by applicant): Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant disorder characterized by ataxia, epilepsy and anticipation. A large expansion of the ATTCT repeat in intron 9 of the SCA10 gene encoding the E46L protein is the mutation responsible for this disease. The mechanism by which the expansion mutation leads to the disease phenotype is unknown. The goal of this project is to elucidate the pathogenic mechanism of SCA10. The long-term goal is to develop a rational therapy for SCA10 based on the pathogenic mechanism. The central hypothesis is that the major pathogenic mechanism of SCA10 is due to the disruption of the normal cellular function of polyprimidine tract binding proteins (PTBs) by the large expanded AUUCU repeat in the E46L RNA. This hypothesis is based on preliminary data that (i) SCA10 cells do not show altered levels of E46L mRNA and protein, (ii) loss of function of the E46L protein does not lead to a SCA10-like phenotype in mice, (iii), expanded ATTCT repeats are transcribed and accumulated in nuclear foci, and (iv) 3 species of PTBs (PTB, nPTB and hnRNP K) bind to AUUCU repeats in vitro and at least 1 (hnRNP K) co-localizes in the nuclear foci in cells derived from an SCA10 patient. The following 2 Specific Aims will be used to test our hypothesis. Specific Aim 1 is to demonstrate that the transcript with an expanded AUUCU repeat gains toxic functions by binding and perturbing the function of PTBs in SCA10 cells. It is expected that (a) there is a detectable level of the expanded AUUCU repeat in SCA10 cells, and (b) expanded AUUCU repeats in SCA10 cells bind to PTBs and alter the cellular functions of PTBs. Specific Aim 2 is to establish genetic mouse models of SCA10. Aim 2 will be accomplished by (a) identifying the SCA10-like phenotype in the transgenic mice that express expanded AUUCU repeats, and (b) establishing genetic mouse models of SCA10 that lack the Hnrpk gene encoding hnRNP K and the Ptbp2 gene encoding the brain-specific nPTB. Transgenic mice expressing expanded AUUCU repeats are expected to exhibit an SCA10-like phenotype by the RNA-mediated gain of function through deficiency of these PTBs. Elucidating the disease mechanism of SCA10 is innovative because SCA10 is the only human disease known to be caused by an expansion of a pentanucleotide repeat. Establishing the mechanism in SCA10 will fill the current gap of knowledge and facilitate the development of rational therapy.

描述（由申请人提供）：脊髓脑性共济失调类型10（SCA10）是一种常染色体显性疾病，其特征是共济失调，癫痫和预期。编码E46L蛋白的SCA10基因内含子9中ATTCT重复的大量扩展是导致该疾病的突变。扩张突变导致疾病表型的机制尚不清楚。该项目的目的是阐明SCA10的致病机理。长期目标是基于致病机制开发针对SCA10的合理疗法。中心假设是SCA10的主要致病机制是由于在E46L RNA中大型膨胀的AUUCU重复重复的多孕激素裂纹结合蛋白（PTB）的正常细胞功能所致。 This hypothesis is based on preliminary data that (i) SCA10 cells do not show altered levels of E46L mRNA and protein, (ii) loss of function of the E46L protein does not lead to a SCA10-like phenotype in mice, (iii), expanded ATTCT repeats are transcribed and accumulated in nuclear foci, and (iv) 3 species of PTBs (PTB, nPTB and hnRNP K)与AUUCU在体外重复和至少1（HNRNP K）在源自SCA10患者的细胞中共定位的1（HNRNP K）。以下两个特定目标将用于检验我们的假设。具体目的1是证明具有扩展的AUUCU重复的转录本通过结合和扰动SCA10细胞中PTB的功能来获得有毒函数。可以预期（a）SCA10细胞中膨胀的AUUCU重复的可检测水平，并且（b）SCA10细胞中的AUUCU重复序列与PTB结合并改变了PTBS的细胞功能。具体目的2是建立SCA10的遗传小鼠模型。 AIM 2将通过（a）在转基因小鼠中识别表达扩大AUUCU重复序列的SCA10样表型，以及（b）建立SCA10的遗传小鼠模型，该模型缺乏编码HNRNP K和PTBP2基因编码大脑特异性NPTB的HNRPK基因。表达膨胀的AUUCU重复序列的转基因小鼠有望通过RNA介导的功能增益通过这些PTB的缺乏表现出SCA10样表型。阐明SCA10的疾病机制具有创新性，因为SCA10是唯一由戊二核苷酸重复膨胀引起的人类疾病。在SCA10中建立机制将填补当前知识的空白，并促进理性治疗的发展。