Redesign Rat Model for ALS Research

描述（由申请人提供）：某些基因的基因突变导致家族性肌萎缩性侧索硬化症（ALS）。为了理解疾病突变的机制，关键的一步是创建一个理想的研究模型。虽然细胞模型对于测试疾病机制的某些方面很重要，但动物模型对于揭示复杂神经退行性变的机制至关重要，因为体外研究的结果并不总是转化为活体动物。当致病性突变表现出显性性状时，通常通过将转基因随机插入宿主基因组来创建动物模型，从而产生基因插入突变和位置效应。转基因表达的水平和模式在很大程度上取决于位置效应，即使两条系携带相同的转基因拷贝，也会因系而异。遗传模型的最佳控制是转基因菌株表达疾病基因的野生型形式，而不产生突变转基因菌株中观察到的表型。不太可能获得两种表达野生型和突变型蛋白水平和模式相似的细胞系。真正的机制往往被传统转基因技术的缺陷所掩盖。为了避免基因插入突变，统一单株间的位置效应，我们将在预定的基因间位点插入单拷贝转基因，并将其与tet诱导系统结合，扩增转基因的表达，从而在大鼠的一生中诱导出合理的表型。利用这些新型大鼠，我们将在系统水平上研究hnRNPA1的发病机制。我们将通过将表型表达与在生理水平和内在模式表达疾病基因的敲入大鼠中观察到的表型表达进行比较，来验证这种新型转基因方法在疾病诱导中的功效。

DESCRIPTION (provided by applicant): Genetic mutation in certain genes causes familial forms of amyotrophic lateral sclerosis (ALS). Toward understanding the mechanisms of a disease mutation, a critical step is creating a desirable model for research. Whereas cellular models are important for testing some aspects of disease mechanisms, animal model is essential for unraveling the mechanisms of complex neurodegeneration because findings from in vitro studies do not always translate to live animals. When a pathogenic mutation exhibits a dominant trait, animal models are often created by randomly inserting transgenes into host genome, incurring gene-insertional mutation and position effects. The levels and patterns of transgene expression largely depend on position effects and vary from line to line even when two lines carry the same copy of transgenes. The best control for genetic model is the transgenic strain that expresses wildtype form of a disease gene but develops no phenotypes observed in mutant transgenic strain. It is unlikely to obtain two lines that express wildtype and mutant proteins at similar levels and patterns. Authentic mechanisms are often obscured by the drawbacks of traditional transgenics. To avoid gene insertional mutation and unify position effect among individual lines, we will insert single copy of transgene at predetermined intergenic locus and will combine it with Tet-inducible system to amplify transgene expression such that plausible phenotypes can be induced within a rat's lifetime. Using these novel rats, we will examine the mechanisms of hnRNPA1 pathogenesis at a systematic level. We will validate the efficacy of this novel transgenic approach in disease induction by comparing phenotypic expression with those observed in the knockin rats that express disease gene at physiological levels and in its intrinsic patterns.