SOD1/Bc1-2 Complex: A Role in Regulating Motor Neuron Cell Death

描述（由申请人提供）：在本项目中，我们将确定铜锌超氧化物歧化酶（SOD 1）在细胞存活和死亡调节中的作用。虽然野生型（WT）SOD 1是一种促生存蛋白，但肌萎缩侧索硬化症（ALS）相关的SOD 1突变体在体外和体内都具有毒性。我们最近发现WT和突变体SOD 1都与抗凋亡蛋白Bcl-2相互作用。然而，突变体SOD 1与Bcl-2结合的性质不同于WT SOD 1。与WT SOD 1相反，突变体SOD 1特异性定位于脊髓线粒体，在那里它形成结合并捕获Bcl-2的SDS抗性高分子量聚集体。（Pasinelli等人，2004，Neuron 43：19-30）。这些研究表明WT SOD 1在调节细胞存活和死亡方面具有潜在的新功能，并且突变体SOD 1具有新的毒性功能获得性。因此，虽然WT SOD 1可以通过其与Bcl-2的相互作用来防止细胞死亡，但是突变体SOD 1可以通过异常结合Bcl-2并将Bcl-2转化为毒性或非功能性蛋白质而变得有毒。为了支持这一假设，我们现在有初步的数据表明，野生型和突变型SOD 1可能需要Bcl-2发挥其抗和促凋亡功能分别。与目前的建议，我们打算表征WT和突变体SOD 1的抗和促死亡功能，以及它们各自与Bcl-2的相互作用。最终目标是了解突变型SOD 1介导的毒性机制，并确定线粒体突变型SOD 1/Bcl-2复合物在ALS发病机制中的潜在作用。具体目标是：1）（A）确定WT SOD 1促存活活性是否依赖于其与Bcl-2的结合，和（B）确定突变SOD 1介导的毒性是否依赖于与Bcl-2的异常相互作用。2)（A）鉴定SOD 1中与Bcl-2结合所必需的区域，和（B）研究WT SOD 1和Bcl-2与突变体SOD 1和Bcl-2之间结合强度的差异。3)（A）为了确定Bcl-2在与突变体SOD 1结合时是否经历构象修饰，(B)在我们的突变型SOD 1-连锁ALS的细胞培养模型上，测试Bcl-2和SOD 1样肽消除Bcl-2和突变型SOD 1之间的结合的潜在益处。4)确定Bcl-2是否介导突变型SOD 1线粒体易位。5)利用转基因ALS小鼠和患者研究突变型SOD 1/Bcl-2聚集体与ALS的相关性。

DESCRIPTION (provided by applicant): In this project we will define a role for copper-zinc superoxide dismutase (SOD1) in the regulation of cell survival and death. While the wild-type (WT) SOD1 is a pro-survival protein, amyotrophic lateral sclerosis (ALS)-linked SOD1 mutants are toxic both in vitro and in vivo. We recently found that both WT and mutant SOD1 interact with the anti-apoptotic protein Bcl-2. However, the nature of the mutant SOD1 binding with Bcl-2 differs from WT SOD1. Contrary to WT SOD1, mutant SOD1 specifically localizes to spinal cord mitochondria where it forms SDS-resistant high molecular weight aggregates that bind and entrap Bcl-2. (Pasinelli et al, 2004, Neuron 43: 19-30). These studies suggest a potentially novel function for WT SOD1 in regulating cell survival and death, and a novel, toxic gain-of-function for mutant SOD1. Thus, while WT SOD1 may protect against cell death through its interaction with Bcl-2, mutant SOD1 may become toxic by aberrantly binding to Bcl-2 and converting Bcl-2 into a toxic or non-functional protein. In support of this hypothesis, we now have preliminary data indicating that both WT and mutant SOD1 might require Bcl-2 to exert their anti-and-pro apoptotic function respectively. With the present proposal we intend to characterize the anti and pro-death function of WT and mutant SOD1 and their respective interactions with Bcl-2. The ultimate goal is to understand the mechanism(s) of mutant SOD1-mediated toxicity and to define a potential role for the mitochondrial mutant SOD1/Bcl-2 complex in ALS pathogenesis. The specific aims are: 1) (A) To determine whether WT SOD1 pro-survival activity depends on its binding to Bcl-2, and (B) to determine whether mutant SOD 1-mediated toxicity depends on the aberrant interaction with Bcl-2. 2) (A) To identify the region(s) in SOD1 essential for the binding with Bcl-2, and (B) to study the difference in binding strength between WT SOD1 and Bcl-2 and mutant SOD1 and Bcl-2. 3) (A) To determine whether Bcl-2 undergoes conformational modifications upon binding with mutant SOD1 and.(B) to test the potential benefit of Bcl-2 and SOD1 like-peptides that abolish binding between Bcl-2 and mutant SOD1 on our cell culture model of mutant SOD1-linked ALS. 4) To determine whether Bcl-2 mediates mutant SOD1 mitochondrial translocation. 5) To study the correlation between mutant SOD1/Bcl-2-containing aggregates and ALS using transgenic ALS mice and patients.