RNA-Targeted Dysregulation of Survival Factors in ALS: HuR to the Rescue

描述(由申请人提供)： 肌萎缩侧索硬化症(ALS)是一种运动神经元退行性疾病，不可避免地导致进行性虚弱和死亡。肌萎缩侧索硬化症在海外战争退伍军人中的发病率显著增加，因此对退伍军人的医疗保健产生了重大影响。可悲的是，这种疾病的病理生理学在很大程度上仍然是一个谜，而且还没有有效的治疗方法。在我们实验室最近的工作中，我们发现生长因子mRNA稳定性和翻译的失调是理解ALS基础的一个新的机制方向。与家族性肌萎缩侧索硬化症相关的铜锌超氧化物歧化酶1突变获得了与许多关键生长和细胞保护因子的5‘和3’非翻译区存在的富U和AU元素的高RNA结合亲和力。通过与细胞RNA结合蛋白(RBP)的相互作用，这些元件控制转录本的稳定性和翻译，并为细胞应激期间生存因子的快速上调提供了重要途径。RBP，HUR，通过与这些元件结合，在这一分子途径中发挥着重要的积极作用。我们之前的研究表明，突变体SOD1通过获得高的RNA结合亲和力，破坏了Hur的稳定和血管内皮生长因子mRNA的翻译，血管内皮生长因子是运动神经元的关键神经保护因子。我们发现，上调HUR可以逆转表达突变型SOD1的细胞的凋亡和线粒体功能障碍。在此基础上，我们推测Hur的上调可以通过直接逆转运动神经元中生存因子mRNAs转录后的异常加工或通过促进周围星形胶质细胞的VEGF产生来挽救由突变型SOD1引起的运动神经元变性。我们有必要的动物细胞模型来测试这种令人兴奋的可能性。这项工作具有真正的潜力，为开发这种毁灭性疾病的新治疗方法奠定了基础。具体目的：1.利用体外和体内小鼠模型，确定Hur能否挽救突变型SOD1在运动神经元和星形胶质细胞中的细胞毒表型。2.检测转基因Hur在运动神经元和星形胶质细胞中的表达对转录后调控和细胞保护因子产生的分子影响。 公共卫生相关性： 肌萎缩侧索硬化症是一种无情的运动神经元疾病，会导致肌肉进行性瘫痪，最终导致死亡。在我们参加过外国战争的退伍军人中，这种疾病的发病率显著增加，而且没有治愈或缓解的治疗方法。这项提议将解决生长因子调节的一个新领域，该领域可能导致这种疾病的原因，从而最终可能导致新的治疗方法。

DESCRIPTION (provided by applicant): Amyotrophic lateral sclerosis (ALS) is a degenerative disease of motor neurons that inexorably leads to progressive weakness and death. The incidence of ALS is significantly increased among veterans of foreign wars, and thus it has a major impact on veteran health care. Sadly, the pathophysiology of this disease remains largely a mystery, and there are no effective treatments. In recent work from our laboratory, we have identified dysregulation of growth factor mRNA stability and translation as a novel mechanistic direction to understanding the basis for ALS. Mutations of Cu, Zn superoxide dismutase (SOD)1 that are associated with familial ALS gain a high RNA binding affinity for U- and AU-rich elements present in 5' and 3' untranslated regions (UTR) of many critical growth and cytoprotective factors. Through an interaction with cellular RNA binding proteins (RBP), these elements govern stability and translation of the transcript and provide an important pathway for rapid upregulation of survival factors during cellular stress. The RBP, HuR, plays a major positive role in this molecular pathway by binding to these elements. We previously showed that mutant SOD1, through its gain of high RNA binding affinity, disrupts HuR stabilization and translation of vascular endothelial growth factor mRNA, a critical neuroprotective factor for motor neurons. We found that apoptosis and mitochondrial dysfunction in cells expressing mutant SOD1 could be reversed by upregulating HuR. Based on this work, we hypothesize here that upregulation of HuR can rescue motor neuron degeneration induced by mutant SOD1 by reversing aberrant post-transcriptional processing of survival factor mRNAs in motor neurons directly or by enhanced VEGF production of surrounding astrocytes. We have the animal cellular models necessary to test this exciting possibility. This work has the real potential to establish a foundation for developing novel therapeutic approaches to this devastating disease. Specific Aims: 1. To determine whether HuR can rescue the cytotoxic phenotype of mutant SOD1 in motor neurons and astrocytes using in vitro and in vivo mouse models. 2. To determine the molecular impact of transgenic HuR expression in motor neurons and astrocytes with regard to posttranscriptional regulation and production of cytoprotective factors. PUBLIC HEALTH RELEVANCE: Amyotrophic lateral sclerosis is a relentless disease of motor neurons that leads to progressive paralysis of the muscles and ultimately death. There is a significantly increased incidence of this disease in our veterans of foreign wars, and there is no cure or mitigating therapy. This proposal will address a novel area of growth factor regulation that may contribute to the cause of this disease, and thus may ultimately lead to novel therapies.