Dysregulation of Multivesicular Body and Exosome Flux in Alzheimer's Disease

阿尔茨海默病(AD)是一种进行性和退行性的脑部疾病。这是病理性的 以淀粉样蛋白(Aβ，Aβ)斑块、神经原纤维缠结(NFT)和神经元丢失为特征。关键事件 阿尔茨海默病发病机制尚不完全清楚。我研究的长期目标是 了解神经元对应激反应的分子和细胞过程，以及神经细胞功能障碍如何 这些反应机制促进了神经退行性变过程。我们建议调查一项新的 外切体生物发生的分子调控及其在AD发病中的作用。胞外体是细胞外的 由细胞分泌的微泡。外切体携带包括蛋白质、脂类和RNA在内的货物，以影响或 改变靶细胞的表型。Exosome可能传播与AD相关的有毒分子，如Aβ、APP、 还有陶。研究表明，调节外切体的水平可以改变Aβ斑块的负荷。一些基本的 参与外切体生物发生的成分是已知的，并且与内吞途径高度相关。这个 多囊泡体的管腔内小泡(ILV)是外切体的细胞来源。随着MVB的融合 有了质膜，ILV以外体的形式释放到细胞外空间。与研究相反 在AD的外切体货物上，鲜为人知的是外切体生物发生机制本身是否以及如何在 对AD相关病原性应激的反应。我们已经研究了内体-溶酶体途径，包括 自噬在神经应激反应中的作用及其在神经退行性疾病中的作用，特别是AD和 帕金森氏症。通过这些努力，我们意外地发现了液泡膜的一个新的作用 蛋白1(VMP1)，以前被证明调节自噬的外周细胞，在外体生物发生中 在神经细胞和它在AD中的参与。我们的初步发现有力地支持了新的假设 VMP1调节神经元中MVB-外切体和-溶酶体网络的流量。AD相关致病 应激增加VMP1促进外切体的生物发生，从而影响供受者的能力 神经元来应对压力。我们建议使用分子和细胞方法，AD转基因动物， 和死后的人标本，以确定在AIM I中VMP1是否控制内体和 神经元中的溶酶体网络和外切体的生物发生及其潜在的分子机制 VMP1介导的外切体生物发生调控在AD相关神经元中是否发生改变 致病应激；在目标III中，是否发生VMP1介导的外切体生物发生的失调以及 转基因AD大鼠模型的神经元应激和病理基础；以及在目标IV中VMP1的状态 人死后阿尔茨海默病脑内的通路。这项研究将极大地促进我们对 调控外切体形成的分子机制和揭示外切体的生物发生过程 AD相关应激源靶向及其在AD发病机制中的作用。

Alzheimer's disease (AD) is a progressive and degenerative disorder of the brain. It is pathologically characterized by amyloid β (Aβ) plaques, neurofibrillary tangles (NFTs), and loss of neurons. The key events driving the pathogenesis in AD are not completely understood. The long-term objective of my research is to understand the molecular and cellular processes by which neurons respond to stress and how dysfunction of these responsive mechanisms contributes to neurodegenerative process. We propose to investigate a new molecular regulator of exosome biogenesis and its role in AD pathogenesis. Exosomes are extracellular microvesicles secreted by cells. Exosomes carry cargos including proteins, lipids, and RNAs to influence or alter the phenotype of the target cells. Exosomes may spread toxic molecules related to AD such as Aβ, APP, and tau. Modulating the level of exosomes has been shown to alter the load of Aβ plaques. Some of the basic components involved in exosome biogenesis are known and highly related to the endocytic pathway. The intraluminal vesicles (ILVs) of multivesicular bodies (MVBs) are the cellular source of exosomes. As MVBs fuse with the plasma membrane, ILVs are released into the extracellular space as exosomes. In contrast to studies on exosome cargos in AD, little is known if and how exosome biogenic machinery itself may be altered in response to the AD related pathogenic stress. We have studied the endosomal-lysosomal pathways including autophagy in neural stress response and their roles in neurodegenerative diseases, particularly AD and Parkinson's disease. With these efforts, we have unexpectedly discovered a novel role for vacuole membrane protein 1 (VMP1), which was previously shown to regulate autophagy peripheral cells, in exosome biogenesis in neural cells and its involvement in AD. Our preliminary findings support strongly the new hypothesis that VMP1 regulates the flux of MVB-exosome and -lysosome network in neurons. AD-associated pathogenic stress increases VMP1 to promote exosome biogenesis, and this impacts the ability of donor and recipient neurons to handle stress. We propose to use molecular as well as cellular approaches, AD transgenic animal, and postmortem human specimens to determine in Aim I whether VMP1 controls the flux of endosomal and lysosomal network and exosome biogenesis in neurons, and its underlying molecular mechanisms; in Aim II whether VMP1-mediated regulation of exosome biogenesis is altered in neurons under AD associated pathogenic stress; in Aim III whether dysregulation of VMP1-mediated exosome biogenesis occurs and underlies neuronal stress and pathology in a transgenic rat model of AD; and in Aim IV the status of VMP1 pathway in postmortem human AD brains. The study will significantly advance our understanding of the molecular mechanisms regulating exosome formation and reveal how the exosome biogenic process is targeted by AD associated stressors and its involvement in AD pathogenesis.