Protective effects of reduced dynamin-related protein 1 against amyloid beta-induced mitochondrial dysfunction and synaptic damage in Alzheimer's disease
Protective effects of reduced dynamin-related protein 1 against amyloid beta-induced mitochondrial dysfunction and synaptic damage in Alzheimer's disease
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DOI：
10.1093/hmg/ddw330
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发表时间：
2016-12-01
影响因子：
3.5
通讯作者：
Reddy, P. Hemachandra
中科院分区：
文献类型：
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作者：
Manczak, Maria;Kandimalla, Ramesh;Reddy, P. Hemachandra
本研究的目的是了解在阿尔茨海默病（AD）的进展和发病机制中，动力蛋白相关蛋白（Drp 1）表达减少对淀粉样蛋白β（Ab）诱导的线粒体和突触毒性的保护作用。我们最近的分子和生物化学研究表明，受损的线粒体动力学增加线粒体碎片和减少融合，在神经元从AD患者的尸检脑和转基因AD小鼠和表达抗体的神经元，这表明抗体导致线粒体碎片在AD。此外，我们最近的免疫共沉淀和免疫染色分析显示，线粒体分裂蛋白Drp 1与抗体相互作用，这种相互作用随着AD的进展而增加。基于这些发现，我们假设部分缺陷的Drp 1抑制Drp 1-A β相互作用，并保护抗体诱导的线粒体和突触毒性，并维持线粒体动力学和神经元功能的AD神经元。我们将Drp 1 +/-小鼠与APP转基因小鼠（Tg 2576系）杂交，并产生双突变（APPXDrp 1 +/-）小鼠。利用实时RT-PCR和免疫印迹分析，我们测量了6个月大的Drp 1 +/-，APP，APPXDrp 1 +/-和野生型（WT）小鼠的线粒体动力学，线粒体生物发生和突触相关基因的mRNA表达和蛋白水平。使用生物化学方法，我们还研究了线粒体功能，并在我们的研究中测量了所有品系小鼠脑组织中的可溶性Ab。与APP小鼠相比，6月龄的APPXDrp 1 +/-小鼠中发现Drp 1和Fis 1（裂变）和CypD（基质）基因的mRNA表达和蛋白水平降低，Mfn 1、Mfn 2和Opa 1（融合）、Nrf 1、Nrf 2、PGC 1 α、TFAM（生物发生）和突触泡蛋白、PSD 95、突触蛋白1、突触小泡蛋白1、神经颗粒蛋白、GAP 43和突触足蛋白（突触）水平升高。线粒体功能测定显示，相对于APP小鼠，APPXDrp 1 +/-小鼠的线粒体功能障碍减少，表明Drp 1减少增强了AD神经元的线粒体功能。夹心ELISA试验显示，相对于APP小鼠，APPXDrp 1 +/-小鼠的可溶性Ab水平显著降低，表明Drp 1降低降低了AD进展中可溶性A β的产生。这些发现表明，部分减少Drp 1减少A β的产生，减少线粒体功能障碍，并保持线粒体动力学，增强APP小鼠的线粒体生物合成和突触活性。这些发现可能对开发基于Drp 1的AD患者治疗方法具有重要意义。
The purpose of our study was to understand the protective effects of reduced expression of dynamin-related protein (Drp1) against amyloid beta (Ab) induced mitochondrial and synaptic toxicities in Alzheimer's disease (AD) progression and pathogenesis. Our recent molecular and biochemical studies revealed that impaired mitochondrial dynamics-increased mitochondrial fragmentation and decreased fusion-in neurons from autopsy brains of AD patients and from transgenic AD mice and neurons expressing Ab, suggesting that Ab causes mitochondrial fragmentation in AD. Further, our recent co-immunoprecipitation and immunostaining analysis revealed that the mitochondrial fission protein Drp1 interacted with Ab, and this interaction increased as AD progressed. Based on these findings, we hypothesize that a partial deficiency of Drp1 inhibits Drp1-A beta interactions and protects Ab-induced mitochondrial and synaptic toxicities, and maintains mitochondrial dynamics and neuronal function in AD neurons. We crossed Drp1+/- mice with APP transgenic mice (Tg2576 line) and created double mutant (APPXDrp1+/-) mice. Using real-time RT-PCR and immunoblotting analyses, we measured mRNA expressions and protein levels of genes related to the mitochondrial dynamics, mitochondrial biogenesis and synapses from 6-month-old Drp1+/-, APP, APPXDrp1+/- and wild-type (WT) mice. Using biochemical methods, we also studied mitochondrial function and measured soluble Ab in brain tissues from all lines of mice in our study. Decreased mRNA expressions and protein levels of Drp1 and Fis1 (fission) and CypD (matrix) genes, and increased levels of Mfn1, Mfn2 and Opa1 (fusion), Nrf1, Nrf2, PGC1 alpha, TFAM (biogenesis) and synaptophysin, PSD95, synapsin 1, synaptobrevin 1, neurogranin, GAP43 and synaptopodin (synaptic) were found in 6-month-old APPXDrp1+/- mice relative to APP mice. Mitochondrial functional assays revealed that mitochondrial dysfunction is reduced in APPXDrp1+/- mice relative to APP mice, suggesting that reduced Drp1enhances mitochondrial function in AD neurons. Sandwich ELISA assay revealed that soluble Ab levels were significantly reduced in APPXDrp1+/- mice relative to APP mice, indicating that reduced Drp1 decreases soluble A beta production in AD progression. These findings suggest that a partial reduction of Drp1 reduces A beta production, reduces mitochondrial dysfunction, and maintains mitochondrial dynamics, enhances mitochondrial biogenesis and synaptic activity in APP mice. These findings may have implications for the development of Drp1 based therapeutics for AD patients.