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

描述（由申请人提供）：我们最近在线粒体膜间隙（IMS-UPR）中发现了一种新的未折叠蛋白反应（UPR）。本应用的重点是IMS-UPR在与错误折叠突变SOD1相关的家族性肌萎缩性侧索硬化症（fALS）中的作用。我们的数据表明，IMS中错误折叠蛋白的积累导致AKT的激活，进而促进雌激素受体α (erα)的磷酸化和激活。反过来，被激活的erα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突变SOD1既定位于细胞质，也定位于IMS。建立细胞系和小鼠模型，其中SOD1-G93A要么存在于细胞质和IMS中，要么只存在于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-部分激活了细胞保护性IMS- upr，但细胞质SOD1G93A对蛋白酶体的抑制并不能限制突变蛋白在IMS中的输入。结果，出现了持续和未解决的ims压力。我们假设，在这些条件下，线粒体损伤增加，IMS-UPR从细胞保护转变为促死亡。我们进一步假设，这种转换最终确实会在仅ims模型中发生，但时间要晚得多。此外，虽然AKT对erα的激活不依赖于雌激素，但它与雌激素协同作用。由于已知雌激素具有神经保护作用，雌激素在IMS-UPR环境中的作用仍有待确定。为了验证我们的假设，我们提出了以下具体目标：具体目标1：在SOD1-G93A和仅ims - SOD1-G93A转基因小鼠的ALS疾病的整个自然历史中监测IMS-UPR。具体目的2：在非靶向和仅ims - SOD1-G93A模型中测试er - α消融对疾病自然史的影响。具体目的3：剖析erα的配体依赖性和配体非依赖性功能在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.