Bhattacharyya Pallabi, Biswas Atanu, Biswas Subhas C
Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India.
Department of Neurology, Bangur Institute of Neurosciences, Kolkata, India.
Front Cell Neurosci. 2023 Jan 12;16:1037903. doi: 10.3389/fncel.2022.1037903. eCollection 2022.
Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with the death of mid-brain dopaminergic neurons. Unfortunately, no effective cure or diagnostic biomarkers for PD are available yet. To address this, the present study focuses on brain-enriched small non-coding regulatory RNAs called microRNAs (miRNAs) that are released into the circulation packaged inside small extracellular vesicles called exosomes. We collected blood samples from PD patients and isolated exosomes from the plasma. qPCR-based detection revealed a particular neuron-enriched miR-128 to be significantly decreased in the patient-derived exosomes. Interestingly, a concomitant decreased expression of miR-128 was observed in the cellular models of PD. Fluorescent live cell imaging and flow-cytometry revealed that over-expression of miR-128 can prevent 6-OHDA-mediated mitochondrial superoxide production and induction of neuronal death respectively. This neuroprotective effect was found to be induced by miR-128-mediated inhibition of FoxO3a activation, a transcription factor involved in apoptosis. miR-128 over-expression also resulted in down-regulation of pro-apoptotic FoxO3a targets- FasL and PUMA, at both transcript and protein levels. Further downstream, miR-128 over-expression inhibited activation of caspases-8, -9 and -3, preventing both the intrinsic and extrinsic pathways of apoptosis. Additionally, over expression of miR-128 prevented down-regulation of synaptic proteins- Synaptophysin and PSD-95 and attenuated neurite shortening, thereby maintaining overall neuronal integrity. Thus, our study depicts the intracellular role of miR-128 in neuronal apoptosis and neurodegeneration and its implications as a biomarker being detectable in the circulating exosomes of PD patient blood. Thus, characterization of such exosomal brain-enriched miRNAs hold promise for effective detection and diagnosis of PD.
帕金森病（PD）是一种与中脑多巴胺能神经元死亡相关的进行性神经退行性疾病。不幸的是，目前尚无针对PD的有效治愈方法或诊断生物标志物。为了解决这一问题，本研究聚焦于一类在大脑中富集的小非编码调节RNA，即微小RNA（miRNA），它们被包裹在称为外泌体的小细胞外囊泡中释放到循环系统中。我们从PD患者中采集血样，并从血浆中分离出外泌体。基于qPCR的检测显示，一种在神经元中特别富集的miR-128在患者来源的外泌体中显著减少。有趣的是，在PD细胞模型中也观察到miR-128表达随之降低。荧光活细胞成像和流式细胞术显示，miR-128的过表达分别可以预防6-OHDA介导的线粒体超氧化物产生和神经元死亡诱导。发现这种神经保护作用是由miR-128介导的对FoxO3a激活的抑制所诱导的，FoxO3a是一种参与细胞凋亡的转录因子。miR-128的过表达还导致促凋亡的FoxO3a靶点FasL和PUMA在转录和蛋白水平上均下调。在更下游，miR-128的过表达抑制了半胱天冬酶-8、-9和-3的激活，从而阻止了细胞凋亡的内在和外在途径。此外，miR-128的过表达预防了突触蛋白突触素和PSD-95的下调，并减轻了神经突缩短，从而维持了整体神经元的完整性。因此，我们的研究描述了miR-128在神经元凋亡和神经退行性变中的细胞内作用，以及其作为一种可在PD患者血液循环外泌体中检测到的生物标志物的意义。因此，对这种外泌体中富集的脑miRNA进行表征有望实现对PD的有效检测和诊断。
