HuR regulates TDP-43 and FUS: implications for ALS pathogenesis

 描述（由申请人提供）： 肌萎缩侧索硬化症（ALS）是一种毁灭性的神经退行性疾病，其中运动神经元的选择性丧失导致致命的瘫痪。无论服役的分支或服役的时间长短，军人患ALS的可能性几乎是军人的两倍，因此它对退伍军人医疗保健的影响是巨大的。然而，对ALS的发病机制知之甚少，并且没有治愈或有效的治疗方法。在过去的二十年里，SOD 1突变的发现一直是ALS研究的驱动力。最近，两种RNA结合蛋白（RBP）TDP-43和FUS与散发性和家族性ALS有关，并强调了异常RNA加工在该疾病发病机制中的作用。TDP-43和FUS是如何调节的尚不清楚。我们已经发现人类抗原R（HuR）是TDP-43和FUS正确表达所必需的。HuR是一种主要的RBP，与TDP-43和FUS具有惊人的结构和功能相似性。我们已经报道了突变SOD 1诱导的细胞毒性，包括细胞凋亡和线粒体功能障碍，可以通过以基因剂量依赖性方式上调HuR来逆转，这表明HuR在神经变性中具有保护作用。我们的初步数据表明，HuR易位到ALS患者脊髓的细胞质中，它特异性地结合TDP-43 3 'UTR，并在正常和应激条件下促进TDP-43和FUS的表达。HuR还调节细胞蛋白的泛素化，这是蛋白酶体正常功能的关键要素。我们推测HuR通过转录后机制正向调节TDP-43和FUS的表达。这种调节的破坏导致受损的细胞应激反应和运动神经元毒性。我们将通过以下具体目标的实验来验证这一假设：1。将HuR定义为TDP-43和FUS的上游调节因子，并评估其对TDP-43剪接功能、细胞应激反应和运动神经元存活的下游影响。2.确定TDP-43的3 'UTR中的顺式调节元件在其交叉和自身转录后调节中的作用，并分析HuR和TDP-43之间的蛋白质-蛋白质和蛋白质-RNA相互作用。3.确定HuR在TDP-43和FUS的翻译调节和蛋白降解中的作用。

 DESCRIPTION (provided by applicant): Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disorder in which selective loss of motor neurons leads to fatal paralysis. Military personnel are nearly twice as likely to develop ALS, regardless of the branch of service or the time period served, thus its impact on veteran health care is enormous. However, little is known about the pathogenesis of ALS, and there is no cure or effective treatment. Discovery of mutations in SOD1 has been the driving force in ALS research for the last two decades. More recently, two RNA binding proteins (RBP), TDP-43 and FUS, have been linked to sporadic and familial ALS, and underscore the role of abnormal RNA processing in the pathogenesis of this disease. How TDP-43 and FUS are regulated is unknown. We have found that Human antigen R (HuR) is required for proper TDP-43 and FUS expression. HuR is a major RBP with striking structural and functional similarities to TDP-43 and FUS. We have reported that cellular toxicity induced by mutant SOD1, including apoptosis and mitochondrial dysfunction, could be reversed by up-regulating HuR in a gene dose-dependent manner, suggesting a protective role of HuR in neurodegeneration. Our preliminary data suggest that HuR translocates to the cytoplasm in spinal cords of ALS patients, it specifically binds to TDP-43 3'UTR and promotes TDP-43 and FUS expression under normal and stressed conditions. HuR also regulates ubiquitination of cellular proteins, a key element in the proper functioning of the proteasome. We hypothesize that HuR positively regulates TDP-43 and FUS expression through posttranscriptional mechanisms. Disruption of this regulation leads to compromised cellular stress response and motor neuron toxicity. We will test this hypothesis by performing experiments with the following specific aims: 1. Define HuR as an upstream regulator of TDP-43 and FUS, and assess its downstream effect on TDP-43 splicing function, cellular stress response and motor neuron survival. 2. Determine the role of cis-regulatory elements in the 3'UTR of TDP-43 in its cross- and self- posttranscriptional regulation, and analyze protein-protein and protein-RNA interactions between HuR and TDP-43. 3. Determine the role of HuR in the translational regulation and protein degradation of TDP-43 and FUS.