Department of Neurochemistry, National Institute of Mental Health and Neurosciences (NIMHANS), No. 2900, Hosur Road, Bangalore, Karnataka, 560029, India.
Department of Radiological Sciences, Ronald Reagan UCLA Medical Center, Los Angeles, CA, 90095, USA.
Sci Rep. 2021 Jan 15;11(1):1483. doi: 10.1038/s41598-020-79339-2.
Mitochondrial dysfunction and neurodegeneration underlie movement disorders such as Parkinson's disease, Huntington's disease and Manganism among others. As a corollary, inhibition of mitochondrial complex I (CI) and complex II (CII) by toxins 1-methyl-4-phenylpyridinium (MPP) and 3-nitropropionic acid (3-NPA) respectively, induced degenerative changes noted in such neurodegenerative diseases. We aimed to unravel the down-stream pathways associated with CII inhibition and compared with CI inhibition and the Manganese (Mn) neurotoxicity. Genome-wide transcriptomics of N27 neuronal cells exposed to 3-NPA, compared with MPP and Mn revealed varied transcriptomic profile. Along with mitochondrial and synaptic pathways, Autophagy was the predominant pathway differentially regulated in the 3-NPA model with implications for neuronal survival. This pathway was unique to 3-NPA, as substantiated by in silico modelling of the three toxins. Morphological and biochemical validation of autophagy markers in the cell model of 3-NPA revealed incomplete autophagy mediated by mechanistic Target of Rapamycin Complex 2 (mTORC2) pathway. Interestingly, Brain Derived Neurotrophic Factor (BDNF), which was elevated in the 3-NPA model could confer neuroprotection against 3-NPA. We propose that, different downstream events are activated upon neurotoxin-dependent CII inhibition compared to other neurotoxins, with implications for movement disorders and regulation of autophagy could potentially offer neuroprotection.
线粒体功能障碍和神经退行性变是帕金森病、亨廷顿病和锰中毒等运动障碍的基础。因此,毒素 1-甲基-4-苯基吡啶(MPP)和 3-硝基丙酸(3-NPA)分别抑制线粒体复合物 I(CI)和复合物 II(CII),会导致这些神经退行性疾病中观察到的退行性变化。我们旨在揭示与 CII 抑制相关的下游途径,并将其与 CI 抑制和锰神经毒性进行比较。与 MPP 和 Mn 相比,暴露于 3-NPA 的 N27 神经元细胞的全基因组转录组学显示出不同的转录组谱。除了线粒体和突触途径外,自噬是 3-NPA 模型中差异调节的主要途径,对神经元存活有影响。该途径是 3-NPA 所特有的,这一点通过对三种毒素的计算机模拟得到了证实。3-NPA 细胞模型中自噬标志物的形态和生化验证显示,自噬是由雷帕霉素复合物 2(mTORC2)途径介导的不完全自噬。有趣的是,3-NPA 模型中升高的脑源性神经营养因子(BDNF)可以对 3-NPA 提供神经保护作用。我们提出,与其他神经毒素相比,神经毒素依赖性 CII 抑制会激活不同的下游事件,这对运动障碍和自噬调节有影响,可能提供神经保护作用。