Study on hnRNPA1 Pathobiology in ALS

 描述(申请人提供)：最近在肌萎缩侧索硬化症(ALS)的多个家族中发现hnRNPA1突变。已知hnRNPA1调节RNA的加工，并与与不同细胞功能相关的蛋白质相互作用，但hnRNPA1突变如何导致疾病尚不清楚。了解hnRNPA1发病机制的关键一步是在系统和分子水平上确定致病突变对hnRNPA1功能的影响。HnRNPA1、TDP-43和FUS属于核糖核蛋白家族，其突变均与ALS相关。这三种核糖核蛋白在疾病特征上有相似之处：1)疾病表现为常染色体显性特征；2)蛋白质病和线粒体损伤在疾病中突出；3)野生型和突变形式在动物模型中过度表达时都会导致疾病。即使在发现肌萎缩侧索硬化症TDP-43突变七年后，TDP-43突变是如何导致这种疾病的仍然难以捉摸。我们的初步研究表明，hnRNPA1表达不足和过度表达分别对hnRNPA1基因敲除和转基因大鼠造成神经毒性，提示必须严格调控hnRNPA1以维持其正常功能。为了揭示致病突变对hnRNPA1的影响，我们创建了hnRNPA1敲门大鼠，其中引入了单一致病突变。在检测的单个核苷酸中，敲门鼠与它们的野生型窝鼠不同。在敲门鼠身上检测到的任何表型都必须是致病突变的结果。通过前所未有的大鼠模型，我们将在系统和分子水平上研究致病突变如何影响hnRNPA1的功能，揭示hnRNPA1突变导致ALS神经变性的机制。

 DESCRIPTION (provided by applicant): Mutations in hnRNPA1 are recently found in multiple families with amyotrophic lateral sclerosis (ALS). HnRNPA1 is known to regulate RNA processing and to interact with proteins related to varying cellular functions, but how hnRNPA1 mutation causes disease is not known. A critical step towards understanding hnRNPA1 pathogenesis is determining the effect of pathogenic mutation on hnRNPA1 function at both systematic and molecular levels. HnRNPA1, TDP-43 and FUS belong to ribonucleoprotein family and their mutations are all associated with ALS. The three ribonucleoproteins exhibit similarity in disease features: 1) the disease shows an autosomal dominant trait; 2) proteinopathy and mitochondrial impairment is prominent in the disease; and 3) both wildtype and mutant forms cause diseases when overexpressed in animal models. Even seven years after the discovery of TDP-43 mutation in ALS, how TDP-43 mutation causes the disease remains elusive. Our preliminary studies show that both deficiency and excess in hnRNPA1 expression causes neurotoxicity respectively in hnRNPA1 knockdown and transgenic rats, suggesting that hnRNPA1 must be tightly regulated to maintain its normal function. To unravel the effect of pathogenic mutation on hnRNPA1, we created hnRNPA1 knockin rats in which a single pathogenic mutation is introduced. The knockin rats differ from their wildtype littermates in a single nucleotide examined. Any phenotypes detected in the knockin rats must result from the pathogenic mutation. With unprecedented rat models, we will examine how pathogenic mutation impacts hnRNPA1 function at both the systematic and molecular levels, revealing the mechanism by which hnRNPA1 mutation causes neurodegeneration in ALS.