STUDY ON NEURODEGENERATION USING TDP-43 TRANSGENIC RATS

 描述（由申请人提供）：在已知的ALS基因中，TDP-43是特别感兴趣的，因为其蛋白质在散发性ALS中被过度磷酸化和泛素化。与基因突变相比，翻译后修饰在患者体内难以检测，在动物模型中也难以复制。因此，了解TDP-43发病机制的关键一步是揭示突变TDP-43导致ALS神经变性的途径。TDP-43与许多RNA和蛋白质结合，但致病性突变如何影响TDP-43功能尚未确定，特别是在适当的动物模型中。出乎意料的是，野生型和突变型TDP-43在啮齿类动物中的过表达导致无法区分的表型，表明过量的TDP-43是神经毒性的。由于转基因表达受到位置效应的严重影响，转基因表达的模式和水平在品系之间变化很大。因此，使用现有的转基因模型无法确定突变TDP-43的毒性是否高于或低于其WT形式。关于致病性突变对TDP-43功能的影响的问题进一步被观察到的TDP-43耗尽诱导TDP-43敲除和敲低小鼠中的神经变性所混淆。由于TDP-43与其自身mRNA的3 '-非翻译区结合，从而调节其自身表达，因此cDNA敲入（KI）方法破坏TDP-43自我调节机制，使得TDP-43 KI动物不是非常有用。即使在ALS中发现TDP-43突变7年后，突变的TDP-43是否通过功能的获得或丧失引起ALS仍然是不确定的，并且这个未解决的问题是解开TDP-43疾病机制的障碍。为了解决这一关键问题，我们通过在大鼠基因组中引入单个疾病相关点突变来创建KI大鼠。通过前所未有的大鼠模型，我们将系统地确定致病性突变如何影响TDP-43的功能。

 DESCRIPTION (provided by applicant): Among known ALS genes, TDP-43 is of particular interest because its protein is hyper-phosphorylated and ubiquitinated in sporadic ALS. Compared with genetic mutation, post-translational modification is difficult to detect in patients and hard to reproduce in animal models. Therefore, a critical step toward understanding TDP-43 pathogenesis is revealing the pathways by which mutant TDP-43 causes neurodegeneration in ALS. TDP-43 binds to many RNAs and proteins, but how pathogenic mutation impacts TDP-43 function has not yet been determined, particularly in an appropriate animal model. Unexpectedly, overexpression of both WT and mutant TDP-43 in rodents causes indistinguishable phenotypes, indicating that excessive TDP-43 is neurotoxic. Because transgene expression is heavily influenced by position effect, the patterns and levels of transgene expression vary greatly from line to line. Whether mutant TDP-43 is more or less toxic than its WT form thus cannot be determined using existing transgenic models. The question regarding the impact of pathogenic mutation on TDP-43 function is further confounded by observations that TDP-43 depletion induces neurodegeneration in TDP-43 knock-out and knock-down mice. As TDP-43 binds to the 3'-untranslated region of its own mRNA and thereby regulates its own expression, the cDNA knock-in (KI) approach destroys TDP-43 self-regulatory machinery, rendering TDP-43 KI animals not very useful. Even 7 years after the discovery of TDP-43 mutation in ALS, whether mutant TDP-43 causes ALS through a gain or loss of function is still uncertain, and this unresolved issue is a roadblock to unraveling TDP-43 disease mechanisms. To resolve this critical issue, we created KI rats by introducing a single disease-linked point mutation into the rat genome. With the unprecedented rat models, we will determine how pathogenic mutation impacts TDP-43 function in a systematic manner.