Mitochondrial inter membrane space-IMS unfolded protein response in familial ALS

描述(申请人提供)：我们最近在线粒体膜间间隙发现了一个新的未折叠蛋白反应(UPR)(IMS-UPR)。这项应用的重点是IMS-UPR在错误折叠突变SOD1相关的家族性肌萎缩侧索硬化症(FALS)中的作用。我们的数据表明，错误折叠的蛋白质在IMS中的积累导致AKT的激活，然后AKT促进雌激素受体α(ERpha)的磷酸化和激活。反过来，激活的ERAlpha促进一系列旨在减少IMS应激的基因的转录。我们和其他人已经证明了突变的SOD1既定位于细胞质，也定位于IMS。建立了细胞系和小鼠模型，其中SOD1-G93A既存在于细胞质中，也存在于IMS中或仅存在于IMS中。我们使用这些模型来测试IMS-UPR的激活。我们在SOD1-G93A ALS细胞系和小鼠模型中的初步数据表明，虽然SOD1G93A的IMS组分激活了细胞保护的IMS-UPR，但胞浆SOD1G93A对蛋白酶体的抑制未能限制突变蛋白在IMS中的输入。结果，持续的和未解决的IMS-应激发生。我们假设，在这些条件下，线粒体损伤增加，IMS-UPR从细胞保护转换为亲死亡。我们进一步假设，这种转换最终确实会在仅支持IMS的模型中发生，但时间要晚得多。此外，虽然AKT对ERa的激活不依赖于雌激素，但它仍与雌激素协同作用。由于已知雌激素具有神经保护作用，雌激素在IMS-UPR的发生中的作用仍有待确定。为了验证我们的假设，我们提出了以下特定目标：特定目标1：在SOD1-G93A和仅IMS-G93A转基因小鼠中监测ALS疾病自然病程中IMS-UPR的情况。具体目标2：在非靶向和仅有IMS的SOD1-G93A模型中，测试ERpha消融对疾病自然病程的影响。具体目标3：剖析ERα的配体依赖和配体非依赖功能在IMS-UPR激活中的作用。

DESCRIPTION (provided by applicant): We have recently identified a new unfolded protein response (UPR) in the mitochondrial inter-membrane space (IMS-UPR). The focus of this application is on the role of the IMS-UPR in familial amyotrophic lateral sclerosis (fALS) associated with misfolded mutant SOD1. Our data indicates that accumulation of misfolded proteins in the IMS leads to the activation of AKT, which then promotes the phosphorylation and activation of the estrogen receptor alpha (ERalpha). In turn, activated ERalpha promotes the transcription of an array of genes aimed at reducing IMS-stress. We and others have demonstrated that mutant SOD1 localizes both to the cytoplasm and the IMS. Cell lines and mouse models were generated, in which SOD1-G93A is either in both the cytoplasm and the IMS or in the IMS-only. We used these models to test the activation of the IMS-UPR. Our preliminary data in cell lines and mouse models of SOD1-G93A ALS suggests that, while the IMS-fraction of SOD1G93A activates a cyto-protective IMS-UPR, the inhibition of the proteasome by cytosolic SOD1G93A fails to limit the import of the mutant protein in the IMS. As a result, sustained and unresolved IMS-stress occurs. We hypothesize that, under these conditions, mitochondrial damage increases and the IMS-UPR switches from being cyto-protective to being pro-death. We further hypothesize that this switch does eventually happen in the IMS-only model but at a much later time. Further, while the activation of the ERalpha by AKT is independent of estrogen, it nevertheless synergizes with estrogen. Since estrogen is known to be neuro-protective, the role of estrogen in the setting of the IMS-UPR remains to be defined. To test our hypothesis we propose the following specific aims: Specific aim 1: Monitoring the IMS-UPR throughout the natural history of the disease in ALS in SOD1-G93A and IMS-only SOD1-G93A transgenic mice. Specific aim 2: Testing the effects of ERalpha ablation on the natural history of the disease in the untargeted and IMS-only SOD1-G93A models. Specific aim 3: Dissecting the role of the ligand-dependent and ligand-independent functions of the ERalpha in the activation of the IMS-UPR.