Role of SUMOylation in Mitochondrial/Synaptic Axis Dysfunction Induced by Abnormal Tau in FTD

摘要 我们对认知和行为障碍背后的分子机制缺乏了解 FTD的这一特点是确定有效治疗方法的关键障碍。该项目将寻求 通过研究SUMO化(我们实验室的一种翻译后修饰)如何解决这一知识缺口 在FTD模型中发现受损，控制Tau聚集和Tau对线粒体的病理作用 以及动物模型中的突触功能以及与Tau突变相关的患者来源的神经元。 相扑，11 kDa相扑(小泛素样修饰物)的共价和可逆连接 蛋白质与靶蛋白质之间的相互作用，与Tau聚集和线粒体动力学有关。确实有 脊椎动物脑中已知的三个相扑类似物，SUMO1-3，其中SUMO2和3具有~95%的序列 同源(且没有功能分化)通常统称为SUMO2/3。而SUMO1 先前报道与Tau的结合促进了其聚集和错误定位，我们发现 SUMO2结合可减少Tau聚集，恢复其在神经元中的正常分布。此外，我们 发现FTD的动物模型，表达Tau突变的P301S(PS19小鼠)显示：1)在 线粒体呼吸链酶(RCE)活性以及突触功能受损(LTP)；以及2) 增加SUMO1-和减少SUMO2-共轭。最重要的是，SUMO2的过度表达得到了改善 体外的RCE活性，以及体内的LTP和记忆。此外，用生物可利用度治疗小鼠 促进SUMO2结合的多肽(BioSenA)，挽救FTD小鼠的LTP和记忆丧失。基座 根据这些初步结果，我们假设聚集和错位的Tau导致线粒体 功能障碍，导致异常的SUMO化和突触缺陷；以及增加SUMO2 结合修复oTau诱导的线粒体缺陷，以及突触功能和记忆，通过防止 Tau聚合。我们将通过以下三个具体目标来检验我们的假设：1.确定因果关系 相扑结合与牛磺酸诱导的线粒体功能障碍的关系 SUMO1的过度表达对线粒体/突触功能有不利影响；3.测试 SUMO2的过度表达挽救了FTD模型中线粒体/突触轴的功能障碍。这些目标将 通过电生理、行为、生物物理和生化的组合来解决 在野生型和转基因小鼠以及来自FTD患者的IPSC来源的神经元中的技术。 在这些实验完成后，我们将确定SUMO化控制 FTD中tau相关损害的发展，并测试针对SUMO2的干预的可能性 结合可以构成治疗他们的一种有效的治疗方法。

Summary Our poor understanding of the molecular mechanisms that underlie the cognitive and behavioral impairments that characterize FTD stands as a critical barrier to identifying effective treatments. This project will seek to address this gap in knowledge by examining how SUMOylation, a post-translational modification that our labs found to be impaired in FTD models, controls Tau aggregation and pathological action of Tau on mitochondrial and synaptic functions in animal models as well as patient-derived neurons associated with Tau mutations. SUMOylation, the covalent and reversible attachment of an 11 kDa SUMO (Small Ubiquitin-like MOdifier) protein to target proteins, has been implicated in both Tau aggregation and mitochondrial dynamics. There are three known SUMO paralogs in vertebrate brains, SUMO1-3, with SUMO2 and 3 sharing ~95% sequence homology (and not functionally differentiated) often collectively referred to as SUMO2/3. While SUMO1 conjugation to Tau was previously reported to promote its aggregation and mislocalization, we found that SUMO2 conjugation reduces Tau aggregation and restores its normal distribution in neurons. Moreover, we found that animal models of FTD, expressing the Tau mutations P301S (PS19 mice) show: 1) deficits in mitochondrial respiratory chain enzymes (RCE) activities, as well as impaired synaptic function (LTP); and 2) increased SUMO1- and reduced SUMO2- conjugation. Most importantly, overexpression of SUMO2 improved RCE activities in vitro, as well as LTP and memory in vivo. Furthermore, treating mice with a bioavailable polypeptide that promotes SUMO2 conjugation (BioSenA), rescued LTP and memory loss in FTD mice. Based on these preliminary results, we hypothesize that aggregated and mislocalized Tau causes mitochondrial dysfunction, which results in aberrant SUMOylation and synaptic deficits; and that increasing SUMO2 conjugation rescues oTau-induced defects in mitochondria, and synaptic function and memory, by preventing Tau aggregation. We will test our hypotheses with the following three specific aims: 1. Determine the causal relationship between SUMO conjugation and Tau-induced mitochondrial dysfunction; 2. Test whether overexpression of SUMO1 has a detrimental effect on mitochondrial/synaptic function; 3. Test whether overexpression of SUMO2 rescues the mitochondrial/synaptic axis dysfunction in FTD models. These aims will be addressed through a combination of electrophysiological, behavioral, biophysical, and biochemical techniques in wild-type and genetically modified mice as well as iPSC-derived neurons from FTD patients. Upon the completion of these experiments, we will identify the mechanisms whereby SUMOylation controls the development of tau-related impairments in FTD, and test the possibility that interventions that target SUMO2 conjugation could constitute an effective therapeutic approach for their treatment.