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

描述（由申请人提供）：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。线粒体是一种动态的细胞器，它经历不断的裂变和融合事件，具有重要的生理功能。越来越多的证据表明，PD和PD模型中线粒体动力学异常，这表明线粒体分裂/融合平衡的改变和线粒体质量控制的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突变导致常染色体显性帕金森病。VPS35是逆转录复合体的关键组成部分，在核内体到高尔基体和核内体到质膜的分选以及许多信号转导事件中起重要作用。最近的研究发现VPS35定位于线粒体，并参与线粒体与其他细胞器之间的胞间通讯。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在神经元中过表达会引起线粒体动力学的显著变化，在表达PD相关VPS35突变体D620N的神经元中，这种变化更为严重。更重要的是，我们发现VPS35与DLP1相互作用，DLP1是线粒体动力学的关键调节因子，通过pd相关突变增强。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，而线粒体动力学可能被VPS35 PD相关突变损害，因此对PS1在线粒体功能和动力学中的潜在作用的详细研究是有必要的。我们提出的研究将是第一个探讨致病性VPS35 PD突变对线粒体动力学/功能和神经元功能影响的机制研究，并可能揭示VPS35在线粒体动力学/功能调节中的新作用。此外，我们提出的研究也将为逆转录物对各种细胞过程和信号通路的贡献提供新的见解。

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.