SOD1/Bcl-2 induced mitochondrial dysfunction in FALS and SALS.

描述（由申请人提供）：肌萎缩侧索硬化症（ALS）是一种破坏性的运动神经元神经退行性疾病，可导致诊断后3-5年内瘫痪和死亡。ALS主要是散发性的（SALS），没有已知的原因。只有一小部分ALS是家族性的（FALS）。因此，在疾病的研究中最大的挑战之一是如何调和疾病机制之间的小部分家族性病例和绝大多数散发病例没有已知的病因。我们必须确定这两种疾病之间的共同致病机制。线粒体病理学是这些常见途径之一，因为在SALS患者和ALS的转基因突变SOD 1（mutSOD 1）小鼠模型中都发现了线粒体缺陷。FALS和SALS中的类似触发因素是否会损害线粒体尚不清楚。使用mutSOD 1表达细胞和转基因小鼠（模拟FALS），以及来自SALS患者的EVB永生化淋巴母细胞，我们确定了一个潜在的共同触发机制。在mutSOD 1小鼠中，我们发现mutSOD 1在线粒体中与Bcl-2异常结合并形成毒性复合物。在这种异常结合后，mutSOD 1诱导Bcl-2的构象变化，通过暴露通常隐藏的毒性BH 3结构域将其转化为有害蛋白。mutSOD 1和构象修饰的Bcl-2共同损害线粒体活力，最终诱导细胞死亡。有趣的是，在上运动神经元发作的SALS患者的一个子集（约30%）中，野生型SOD 1的氧化形式异常结合Bcl-2，通过暴露BH 3结构域将Bcl- 2转化为毒性分子，类似于我们报道的mutSOD 1。通过这种竞争性的更新，我们打算专注于这种共同的线粒体功能障碍途径，这些线粒体功能障碍途径由SALS患者的一个子集和SALS患者共享。我们将在体内测试的假设，Bcl-2的构象变化，导致暴露的毒性BH 3域是一个重要的机制，在SOD 1诱导的线粒体功能障碍（AIM 1）。然后，我们将通过识别关键的下游线粒体靶点（AIM 2）和确定SOD 1/Bcl-2介导的线粒体功能障碍（AIM 3）的细胞特异性来表征SOD 1和Bcl-2之间的毒性复合物的功能意义。最后，我们将测试SOD 1样肽抑制与Bcl-2结合对SOD 1介导的细胞死亡（AIM 4）的有益作用。 最终的目标是确定靶向治疗，其疗效超出了有限的部分家族性病例。

DESCRIPTION (provided by applicant): Amyotrophic Lateral Sclerosis (ALS) is a devastating neurodegenerative disease of the motor neurons, which leads to paralysis and death within 3-5 years from diagnosis. ALS is mainly sporadic (SALS) without a known cause. Only a small fraction of ALS is familial (FALS). Thus, one of the biggest challenges in the study of the disease is how to reconcile disease mechanisms among the small percentage of familial cases and the vast majority of sporadic cases with no known etiology. It is crucial that we identify common pathogenic mechanisms between the two forms of the disease. Mitochondrial pathology is one of these common pathways, as mitochondria defects have been found in both SALS patients and transgenic mutant SOD1 (mutSOD1) mice model of ALS. Whether similar triggers in FALS and SALS damage the mitochondria is not known. Using mutSOD1 expressing cells and transgenic mice (to mimic FALS), as well as EVB immortalized lymphoblasts from SALS patients, we identified a potentially common trigger mechanism. In mutSOD1 mice, we showed that mutSOD1 aberrantly binds and forms a toxic complex with Bcl-2 in mitochondria. Upon this aberrant binding, mutSOD1 induces a conformational change in Bcl-2 that transforms it into a harmful protein by exposing the normally hidden toxic BH3 domain. Together, mutSOD1 and conformationally modified Bcl-2 impair mitochondrial viability, eventually inducing cell death. Interestingly, in a subset (~ 30%) of SALS patients with upper motor neuron onset, an oxidized form of wild type SOD1 aberrantly binds to Bcl-2, transforming Bcl- 2 into a toxic molecule through exposure of the BH3 domain, similarly to what we have reported for mutSOD1. With this competing renewal, we intend to focus on this common pathway of mitochondrial dysfunction shared by FALS-SOD1 and a subset of SALS patients. We will test in vivo the hypothesis that the conformational change in Bcl-2 leading to exposure of the toxic BH3 domain is an important mechanism in SOD1-induced mitochondrial dysfunction (AIM 1). We will then characterize the functional implications of the toxic complex between SOD1 and Bcl-2 by identifying key downstream mitochondrial target(s) (AIM 2) and determining the cellular specificity of the SOD1/Bcl-2-mediated mitochondrial dysfunction (AIM 3). Finally, we will test the beneficial effect of SOD1-like peptides that inhibit binding to Bcl-2 against SOD1-mediated cell death (AIM 4). The ultimate goal is to identify target-based therapies whose efficacy goes beyond the limited portion of familial cases.