Parkin Interacting Proteins

描述（由申请人提供）：parkin基因突变导致PARK2，一种主要的早发常染色体隐性形式的帕金森病。帕金森突变也见于以震颤为主的晚发型帕金森病（PD）患者，与特发性帕金森病难以区分。Parkin是一种E3泛素连接酶，通过蛋白酶体依赖的蛋白质降解途径将泛素链连接到几种蛋白质上。一些与帕金森氏蛋白相互作用的蛋白质，如a-synuclein和synphilin-1，已经被发现在突变时引起帕金森氏病。在之前的实验中，我们确定了突触结合蛋白（syt）家族的两个成员作为parkin结合物。我们现在已经确定了一种新的与突触蛋白同源的帕金森结合蛋白，称为突触蛋白样蛋白（SLP）。PD患者的路易小体中均存在SLP和synaptotagmin XI。我们将测试以下假设：1)parkin相互作用并调节一组选定的突触囊泡相关蛋白。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含有致病突变或易感序列变异。我们提出了两个具体目标：1)我们将进一步表征parkin-SLP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是否会加速SLP的降解。2)我们将在两组PD患者和5个匹配的对照组中探索SLP、SYT1和SYT11基因的序列变异。我们将确定哪些变体代表罕见的致病突变，哪些变体可能构成易感等位基因。变体将使用体外实验测试细胞毒性。这项R21提案的最终目标是进一步表征参与帕金功能的蛋白质，并筛选PD患者中这些蛋白质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.