Parkin Interacting Proteins

描述(申请人提供)：parkin基因突变导致PARK2，一种主要起病的常染色体隐性帕金森症形式。帕金森突变也在震颤为主的晚发型帕金森病(PD)患者中发现，与特发性帕金森病无法区分。Parkin是一种E3泛素连接酶，它将泛素链连接到几种蛋白质上，通过蛋白酶体依赖的蛋白质降解途径进行降解。一些与parkin相互作用的蛋白质，如α-突触核蛋白和突触蛋白-1，已被发现在突变时本身就会导致帕金森氏症。在之前的实验中，我们发现synaptopagmin(Syt)家族的两个成员是parkin结合子。我们现在已经鉴定出一种与突触素同源的新的parkin结合蛋白，命名为突触素样蛋白(SLP)。SLP和SYNAPTOAGMIN XI均存在于PD患者的路易体中。我们将检验以下假设：1)Parkin相互作用并调节一组特定的突触小泡相关蛋白。2)在家族性或散发性帕金森病患者中，编码这些蛋白的基因包含致病突变或易感序列变异。我们提出了两个具体的目标：1)我们将进一步研究Parkin-SLP的相互作用，并研究突变的Parkins是否失去了结合SLP或泛素化SLP的能力。我们将确定Parkin是否加速SLP的降解。2)研究SLP、SYT1和SYT11基因在两个PD患者组和五个匹配的对照组中的序列变异。我们将确定哪些变异代表罕见的致病突变，哪些变异可能构成易感等位基因。变异体将使用体外试验进行细胞毒性测试。这项R21建议的最终目标是进一步表征与Parkin功能有关的蛋白质，并筛选这些蛋白质在PD患者中的突变或易感等位基因。

DESCRIPTION (provided by applicant): Mutations in the parkin gene cause PARK2, a predominantly early-onset autosomal recessive form of Parkinsonism. Parkin mutations are also found in patients with tremor-predominant later onset forms of Parkinson disease (PD) indistinguishable from idiopathic Parkinson's disease. Parkin is an E3 ubiquitin ligase that attaches ubiquitin chains to several proteins destined for degradation through the proteasome-dependent protein degradation pathway. Some proteins that interact with parkin, such as a-synuclein and synphilin-1, have themselves been found to cause Parkinson's disease, when mutated. In previous experiments, we identified two members of the synaptotagmin (syt) family as parkin binders. We have now identified a novel parkin-binding protein with homologies to synapsin, designated synapsin-like-protein (SLP). SLP and synaptotagmin XI are both found in Lewy bodies of PD patients. We will test the following hypotheses: 1) parkin interacts and regulates a select group of synaptic vesicle associated proteins. 2) Genes encoding these proteins contain causative mutations or predisposing sequence variants in patients with familial or sporadic forms of Parkinsonism. Two Specific Aims are proposed: 1) We will further characterize the parkin-SLP interaction, and investigate whether mutant parkins lose the ability to bind SLP or to ubiquitinate SLP. We will determine whether parkin accelerates degradation of SLP. 2) We will explore sequence variants in the SLP, SYT1 and SYT11 genes in two PD patient groups and five matched control groups. We will establish which variants represent rare causative mutations and which variants may constitute susceptibility alleles. Variants will be tested for cell toxicity using an in vitro assay. The ultimate goal of this R21 proposal is to further characterize proteins involved in parkin function and to screen these proteins for mutations or susceptibility alleles in PD patients.