Study on PFN1 Pathobiology Using Rat Models

Profilin 1（PFN 1）的致病性突变是肌萎缩侧索硬化症（ALS）的病因。PFN 1已经 广泛研究了它的生物学和最近的病理学，但PFN 1突变如何导致疾病， 还有待确定。了解疾病基因的关键一步是确定其总体影响 致病性突变对基因功能的影响在系统和分子水平上都存在。ALS是一种神经系统疾病 因此必须在脊椎动物中确定致病突变对PFN 1功能的总体影响 因为人类中枢神经系统的复杂性不能在细胞中充分模拟， 无脊椎动物ALS的有效动物模型应满足至少三个标准： ALS的主要表型包括上运动神经元和下运动神经元的进行性变性， 骨骼肌失神经萎缩;表现出ALS表型的中期或晚期发作， 散发性和大多数遗传性ALS;并显示野生型和突变型之间的分化疾病表型 转基因株系一种理想的人类疾病动物模型是基因敲入，其中一个单一的致病基因， 将突变引入动物基因组中，使得致病性突变在生理上表达， 水平和内在模式，模拟模式和接合性的基因表达，观察到在 患者由于通常用于模拟人类疾病的动物（即小鼠和大鼠）寿命较短（2-3 与人类（平均80岁）相比，疾病基因在生理水平上的表达可能 不足以诱导疾病表型的全谱。因此，基因过表达模型（即， 转基因）经常被用作研究遗传疾病的敲入模型的替代物。解开 致病性突变对PFN 1功能的总体影响，我们创造了符合PFN 1转基因大鼠 有效ALS模型的标准，并建立了表达PFN 1突变的PFN 1敲入大鼠， 它的内源性基因座。基因敲入大鼠与其野生型同窝仔在单个核苷酸检查不同。任何 在敲入大鼠中检测到的表型必须是由引入的致病突变引起的。使用PFN 1 转基因和基因敲入大鼠作为互补模型，我们将确定致病性的整体效果， PFN 1突变在系统和分子水平上发挥作用，揭示了 PFN 1突变导致疾病。PFN 1大鼠模型将成为继SOD 1之后第二个有效的ALS模型 转基因啮齿动物，因此将满足ALS研究在疾病机制和 在一个模型中发现的治疗效果必须在其他模型中确定， 不同ALS基因之间的分歧，因为遗传性ALS中揭示了会聚性疾病机制 模型将更好地预测散发性ALS。

Pathogenic mutation of profilin 1 (PFN1) is causative to amyotrophic lateral sclerosis (ALS). PFN1 has been examined extensively on its biology and recently on its pathobiology, but how PFN1 mutation causes the disease remains to be determined. A critical step towards understanding a disease gene is determining the overall effect of pathogenic mutation on the gene function at both systemic and molecular levels. ALS is a neurological disease and thus the overall effect of pathogenic mutation on PFN1 function must be determined in a vertebrate animal model because the complexity of the human central nervous system cannot be adequately simulated in cells or invertebrate animals. An effective animal model for ALS should meet at least three criteria: recapitulate the cardinal phenotypes of ALS including progressive degeneration of both upper and lower motor neurons and denervation atrophy of skeletal muscles; manifest the middle or late onset of ALS phenotypes that is common to sporadic and most inherited ALS; and display a differentiated disease phenotype between wild-type and mutant transgenic lines. An ideal animal model for human disease is gene knockin in which a single disease-causing mutation is introduced into the animal genome such that the pathogenic mutation is expressed at physiological levels and in intrinsic patterns, simulating the patterns and zygosities of gene expression that are observed in patients. As animals commonly used to model human diseases (i.e. mice and rats) have a shorter life span (2-3 years at maximum) than human (80 years on average), expression of a disease gene at physiological levels may not be sufficient to induce a full spectrum of disease phenotypes. Therefore, gene-overexpressing models (i.e. transgenics) are often used as the substitutes of knockin models for studying inherited diseases. To unravel the overall effect of pathogenic mutation on the PFN1 functions, we have created PFN1 transgenic rats that meet the criteria of effective ALS model and also have created PFN1 knockin rats that express PFN1 mutation from its endogenous locus. 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 introduced. Using PFN1 transgenic and knockin rats as complementary models, we are going to determine the overall effect of pathogenic mutation on PFN1 function at both systemic and molecular levels, revealing the authentic mechanisms by which PFN1 mutation causes the disease. Our PFN1 rat models will be the second effective ALS model after SOD1 transgenic rodents and thus will meet the compelling need of ALS research in that disease mechanisms and therapeutic efficacies discovered in one model must be determined in the other models for the convergence and divergence among varying ALS genes because convergent disease mechanisms revealed in genetic ALS models will have a better prediction of sporadic ALS.