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

描述（由申请人提供）：肌萎缩性侧索硬化症（ALS）是一种运动神经元的破坏性神经退行性疾病，可在诊断后3-5年内导致瘫痪和死亡。肌萎缩侧索硬化症主要是散发性（SALS），病因不明。只有一小部分ALS是家族性的（FALS）。因此，该疾病研究的最大挑战之一是如何协调少数家族病例和绝大多数病因不明的散发病例之间的疾病机制。至关重要的是，我们要确定两种形式的疾病之间的共同致病机制。线粒体病理是这些常见的途径之一，在ALS患者和转基因突变体SOD1 （mutSOD1）小鼠ALS模型中都发现了线粒体缺陷。FALS和SALS的类似触发因素是否会损害线粒体尚不清楚。使用mutSOD1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，我们确定了一种潜在的共同触发机制。在mutSOD1小鼠中，我们发现mutSOD1在线粒体中与Bcl-2异常结合并形成毒性复合物。在这种异常结合中，mutSOD1诱导Bcl-2的构象变化，通过暴露通常隐藏的有毒BH3结构域将其转化为有害蛋白。mutSOD1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，在上运动神经元发病的SALS患者的一部分（约30%）中，野生型SOD1的氧化形式异常地与Bcl-2结合，通过暴露于BH3结构域将Bcl-2转化为有毒分子，类似于我们报道的mutSOD1。有了这种竞争性的更新，我们打算专注于FALS-SOD1和一部分SALS患者共享的线粒体功能障碍的共同途径。我们将在体内验证Bcl-2构象变化导致毒性BH3结构域暴露是sod1诱导的线粒体功能障碍的重要机制（AIM 1）。然后，我们将通过鉴定关键下游线粒体靶点（AIM 2）和确定SOD1/Bcl-2介导的线粒体功能障碍的细胞特异性（AIM 3）来表征SOD1和Bcl-2之间毒性复合物的功能影响。最后，我们将测试抑制与Bcl-2结合的sod1样肽对sod1介导的细胞死亡的有益作用（AIM 4）。最终的目标是确定以靶向为基础的治疗方法，其疗效超出了家族病例的有限部分。

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.