Elucidating the Pathogenic Mechanisms of VPS35 Mutations in Parkinson's Disease

描述(申请人提供)：线粒体功能障碍在帕金森病(PD)的发病机制中起着重要作用。线粒体是动态细胞器，经历着持续的分裂和融合事件，具有至关重要的生理功能。越来越多的证据表明，在PD和PD模型中，线粒体动力学异常，提示线粒体分裂/融合平衡改变和线粒体质量控制受损可能是导致线粒体和神经元功能障碍/变性的共同机制，对PD的发病至关重要。VPS35基因突变导致常染色体显性遗传性帕金森病。VPS35是逆转聚体复合体的关键成分，对于内体到高尔基体和内体到质膜的分离和许多信号事件都是重要的。最近的研究发现VPS35在线粒体上的定位及其参与线粒体与其他细胞器之间的细胞器间通讯。在我们的初步研究中，我们证实了VPS35在人神经母细胞瘤细胞和人脑海马神经元中的线粒体定位。我们进一步发现，野生型VPS35在神经元中的过度表达导致线粒体动力学的显著变化，这种变化在表达PD相关VPS35突变体D620N的神经元中变得更加严重。更重要的是，我们发现VPS35与DLP1物理上相互作用，DLP1是线粒体动力学的关键调节因子，PD相关突变增强了DLP1的作用。所有这些令人兴奋的发现强烈表明VPS35参与了线粒体动力学的调节，而VPS35 PD相关突变可能会损害线粒体动力学，因此有必要对PS1在线粒体功能和动力学中的潜在作用进行详细的研究。我们的研究将是第一次研究致病的VPS35 PD突变对线粒体动力学/功能和神经元功能的影响的机制研究，并可能揭示VPS35在线粒体动力学/功能调节中的新作用。此外，我们提出的研究还将为逆转录增殖体在各种细胞过程和信号通路中的作用提供新的见解。

DESCRIPTION (provided by applicant): Mitochondrial dysfunction plays a prominent role in the pathogenesis of Parkinson's disease (PD). Mitochondria are dynamics organelles that undergo continual fission and fusion events which serve crucial physiological function. Increasing evidence demonstrated abnormal mitochondrial dynamics in PD and PD models, suggesting that an altered balance in mitochondrial fission/fusion and impaired mitochondrial quality control was likely a common mechanism leading to mitochondrial and neuronal dysfunction/degeneration critical to the pathogenesis of PD. Mutations in VPS35 cause autosomal dominant PD. VPS35 is a key component of the retromer complex, which is important for endosome-to-golgi and endosome-to-plasma membrane sorting and many signaling events. Recent studies found the localization of VPS35 on mitochondria and its involvement in inter-organelle communication between mitochondria and other organelles. In our preliminary studies, we confirmed the mitochondrial localization of VPS35 in both human neuroblastoma cells and human brain hippocampal neurons. We further found that overexpression of wild-type VPS35 in neurons caused significant changes of mitochondrial dynamics, which became more severe in neurons expressing PD- associated VPS35 mutant D620N. More importantly, we found that VPS35 physically interacted with DLP1, a key regulator of mitochondrial dynamics, which was enhanced by PD-associated mutation. All these exciting findings strongly suggest that VPS35 were involved in the regulation of mitochondrial dynamics which may be impaired by VPS35 PD associated mutations and detailed investigation into the potential role of PS1 in mitochondrial function and dynamics is warranted. Our proposed study will be the first mechanistic study investigating the effect of the pathogenic VPS35 PD mutations on mitochondrial dynamics/function and neuronal function and will likely reveal a novel role of VPS35 in the regulation of mitochondrial dynamics/function. In addition, our proposed studies will also provide novel insights into the contribution of retromer to various cellular processes an signaling pathways.