Dysregulation of VEGF RNA Stability in Amyotrophic Lateral Sclerosis

描述（由申请人提供）：项目概述：肌萎缩侧索硬化症（ALS）是一种破坏性疾病。最近的证据表明，血管内皮生长因子（VEGF）是细胞应激期间神经保护的关键因素，并且其在神经组织中的下调有助于加速运动神经元死亡。响应于细胞应激而促进VEGF上调的一种分子途径是RNA稳定化。然而，当细胞暴露于应激时，如缺氧暴露、氧化代谢物或炎性细胞因子暴露，VEGF转录物变得稳定，导致表达增强和随后的神经保护。在我们对ALS的超氧化物歧化酶（SOD 1）突变小鼠模型的初步研究中，我们观察到与VEGF RNA不稳定相关的VEGF mRNA水平显著降低。在这个提议中，我们将测试两个密切相关的假设：1）VEGF不稳定和下调是由于RNA稳定剂HuR在突变体SOD1存在下的功能障碍。2)星形胶质细胞和神经元之间的细胞间信号传导触发异常的VEGF mRNA稳定化反应。提出了三个具体目标来检验这些假设。首先，我们将研究胞质HuR易位和突变体SOD 1在VEGF mRNA不稳定和下调中的作用。其次，我们将分析突变体SOD1蛋白、HuR和与VEGF 3'UTR相关的RNP复合物之间的相互作用，以确定突变体SOD1为什么会对VEGF RNA加工产生负面影响。第三，我们将研究突变体SOD1诱导的VEGF不稳定的运动神经元样细胞和表达野生型或突变体SOD1的神经胶质细胞的共培养模型的影响。相关性：这一提议有望阐明VEGF在突变型SOD1小鼠中下调的机制，并提供ALS病理学两个重要方面之间可能的分子联系：VEGF和SOD1突变蛋白。对这种联系的进一步研究可以深入了解ALS的发病机制，并最终为这种目前无法治愈的疾病提供治疗干预。

DESCRIPTION (provided by applicant): Project Summary: Amyotrophic lateral sclerosis (ALS) is a devastating disease. Recent evidence indicates that vascular endothelial growth factor (VEGF) is a critical element for neuroprotection during cellular stress, and that its down-regulation in neural tissues contributes to accelerated motor neuron death. One molecular pathway that promotes VEGF up-regulation in response to cellular stress is RNA stabilization. When cells are exposed to stress, such as hypoxic exposure, oxidative metabolites, or inflammatory cytokine exposure, however, the VEGF transcript becomes stabilized, resulting in enhanced expression and subsequent neuroprotection. In our preliminary studies with the superoxide dismutase (SOD1) mutant mouse model of ALS, we have observed a marked diminution of VEGF mRNA levels that is linked to VEGF RNA destabilization. In this proposal, we will test two closely related hypotheses: 1) VEGF destabilization and down-regulation is due to dysfunction of the RNA stabilizer, HuR, in the presence of mutant SOD1. 2) Intercellular signaling between astrocytes and neurons triggers the aberrant VEGF mRNA stabilization response. Three specific aims are proposed to test these hypotheses. First, we will investigate the role of cytoplasmic HuR translocation and mutant SOD1 in the destabilization and down-regulation of VEGF mRNA. Second, we will analyze the interaction between mutant SOD1 proteins, HuR and the RNP complex associated with the VEGF 3'UTR to determine why mutant SOD1 negatively affects VEGF RNA processing. Third, we will investigate the impact of the mutant SOD1-induced VEGF destabilization in a co-culture model of motor neuron-like cells and glial cells that express wild-type or mutant SOD1. Relevance: This proposal has the promise to elucidate the mechanism by which VEGF is down regulated in mutant SOD1 mice, and to provide a possible molecular link between two important aspects of ALS pathology: VEGF and SOD1 mutant proteins. Further investigation of this link could provide insight into the pathogenesis of ALS, and ultimately therapeutic intervention for this currently incurable disorder.