Kandimalla Ramesh, Manczak Maria, Fry David, Suneetha Yeguvapalli, Sesaki Hiromi, Reddy P Hemachandra
Garrison Institute on Aging, Texas Tech University Health Sciences Center, 3601 4th Street, MS 9424, Lubbock, TX 79430, USA.
Cell Biology Department, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 109 Hunterian, Baltimore, MD 21205, USA.
Hum Mol Genet. 2016 Nov 15;25(22):4881-4897. doi: 10.1093/hmg/ddw312.
The purpose of our study was to understand the protective effects of a partial reduction of dynamin-related protein 1 (Drp1) in Alzheimer’s disease (AD) progression and pathogenesis. Increasing evidence suggests that phosphorylated Tau and mitochondrial abnormalities are involved in the loss of synapses, defective axonal transport and cognitive decline, in patients with AD. In the current study, we investigated whether a partial reduction of Drp1 protect neurons from phosphorylated Tau-induced mitochondrial and synaptic toxicities in AD progression. We crossed Drp1+/− mice with Tau transgenic mice (P301L line) and created double mutant (TauXDrp1+/−) mice. Using real-time RT-PCR, immunoblotting and immunostaining analyses, we measured mRNA expressions and protein levels of genes related to the mitochondrial dynamics—Drp1 and Fis1 (fission), Mfn1, Mfn2 and Opa1 (fusion), CypD (matrix), mitochondrial biogenesis—Nrf1, Nrf2, PGC1α and TFAM and synaptic—synaptophysin, PSD95, synapsin 1, synaptobrevin 1, neurogranin, GAP43 and synaptopodin in brain tissues from 6-month-old Drp1+/−, Tau, TauXDrp1+/− and wild-type mice. Using biochemical and immunoblotting methods, mitochondrial function and phosphorylated Tau were measured. Decreased mRNA and protein levels of fission and matrix and increased levels of fusion, mitochondrial biogenesis, and synaptic genes were found in 6-month-old TauXDrp1+/− mice relative to Tau mice. Mitochondrial dysfunction was reduced in TauXDrp1+/− mice relative to Tau mice. Phosphorylated Tau found to be reduced in TauXDrp1+/− mice relative to Tau mice. These findings suggest that a partial reduction of Drp1 decreases the production of phosphorylated Tau, reduces mitochondrial dysfunction, and maintains mitochondrial dynamics, enhances mitochondrial biogenesis and synaptic activity in Tau mice. Findings of this study may have implications for the development of Drp1 based therapeutics for patients with AD and other tauopathies.
我们研究的目的是了解动力相关蛋白1（Drp1）部分减少对阿尔茨海默病（AD）进展和发病机制的保护作用。越来越多的证据表明，磷酸化Tau和线粒体异常与AD患者的突触丧失、轴突运输缺陷和认知衰退有关。在本研究中，我们调查了Drp1的部分减少是否能在AD进展中保护神经元免受磷酸化Tau诱导的线粒体和突触毒性。我们将Drp1+/-小鼠与Tau转基因小鼠（P301L系）杂交，培育出双突变（TauXDrp1+/-）小鼠。通过实时逆转录聚合酶链反应、免疫印迹和免疫染色分析，我们测量了6月龄Drp1+/-、Tau、TauXDrp1+/-和野生型小鼠脑组织中与线粒体动力学相关基因（Drp1和Fis1（裂变）、Mfn1、Mfn2和Opa1（融合）、CypD（基质））、线粒体生物合成相关基因（Nrf1、Nrf2、PGC1α和TFAM）以及突触相关基因（突触素、PSD95、突触蛋白1、突触小泡蛋白1、神经颗粒素、GAP43和突触足蛋白）的mRNA表达和蛋白质水平。使用生化和免疫印迹方法，测量线粒体功能和磷酸化Tau。相对于Tau小鼠，6月龄TauXDrp1+/-小鼠中裂变和基质的mRNA和蛋白质水平降低，融合、线粒体生物合成和突触基因水平升高。相对于Tau小鼠，TauXDrp1+/-小鼠的线粒体功能障碍减少。相对于Tau小鼠，TauXDrp1+/-小鼠中磷酸化Tau减少。这些发现表明，Drp1的部分减少可降低磷酸化Tau的产生，减少线粒体功能障碍，维持线粒体动力学，增强线粒体生物合成和Tau小鼠的突触活性。本研究结果可能对开发基于Drp1的AD及其他tau蛋白病治疗方法具有重要意义。
