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

描述(申请人提供)：肌萎缩侧索硬化症(ALS)是一种毁灭性的运动神经元退行性疾病，在确诊后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(SAL)，原因不明。只有一小部分ALS是家族性的(FALS)。因此，疾病研究中最大的挑战之一是如何协调一小部分家族性病例和绝大多数原因不明的散发性病例的发病机制。至关重要的是，我们必须确定这两种疾病之间的共同致病机制。线粒体病理是这些常见途径之一，因为在SALS患者和ALS转基因突变SOD1(Mutod1)小鼠模型中都发现了线粒体缺陷。目前尚不清楚FALS和SALS中类似的触发因素是否会损害线粒体。使用表达musod1的细胞和转基因小鼠(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mtSOD1小鼠中，我们发现mtSOD1异常结合并与线粒体中的bcl2形成毒性复合体。在这种异常结合的基础上，musod1诱导了Bcl-2的构象变化，通过暴露通常隐藏的有毒BH3结构域将其转变为有害蛋白质。共同作用，mutod1和构象修饰的bcl2削弱了线粒体的活性，最终导致细胞死亡。有趣的是，在一组上运动神经元发病的SALS患者中(约30%)，野生型SOD1的氧化形式异常地与Bcl-2结合，通过暴露BH3结构域将Bcl-2转化为有毒分子，类似于我们对mutod1的报道。随着这种竞争性的更新，我们打算将重点放在FALS-SOD1和SALS患者的子集共享的线粒体功能障碍的这一共同途径上。我们将在体内验证这一假设，即Bcl-2的构象变化导致有毒BH3结构域的暴露是SOD1诱导的线粒体功能障碍(AIM 1)的一个重要机制。然后，我们将通过确定关键的下游线粒体靶点(S)(AIM2)和确定SOD1Bcl2介导的线粒体功能障碍(AIM3)的细胞特异性来表征SOD1Bcl2之间的毒性复合体的功能含义。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(AIM4)的有益效果。最终目标是确定其疗效超出家族性病例的有限部分的靶向疗法。

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.