低强度激光促进线粒体融合的信号转导机制研究

Alzheimer's disease (AD) is one of the most serious challenges in the field of geratology. Remaining physical and mental stimulation do not seem affected the underlying brain alterations involved in Alzheimer's disease in most individuals. Currently, there is no cure for AD, although drug treatments may help with behavioral symptoms, but have limited efficacy in patients with medium and advanced AD. Neuronal apoptosis induced by amyloid beta protein (Aβ) in senile plaques is the main pathologic feature of AD. We have shown that noninvasive Low-level Laser Irradiation at 808 nm (LLI808) significantly suppressed Aβ1-42-induced hippocampal neurodegeneration of adult male rats through shifting their mitochondrial dynamics toward fusion against Aβ1-42-induced extensive fragmentation. But the related cellular signal transduction pathways and its mechanism are still not clear. Herein, we use Aβ1-42-induced neurotoxicity in neural-like differentiated rat pheochromocytoma PC12 cells as our cellular model, apply daily LLI808 treatment after Aβ1-42 treatment for three consecutive days to attenuate Aβ1-42-induced apoptosis, and investigate the signal transduction pathways of LLI808 by using molecular approaches such as gene knock-out, overexpression and RNA-Seq. This study would provide groundwork for mitochondrial mechanism study of LLI808 and future laser application in clinical therapy and drug development for AD.

阿尔茨海默病（AD）是老年医学最为严峻的问题之一。保持身体运动和脑力活动似乎无法影响潜在的AD脑变化。临床用药物针对减轻AD症状，对中晚期患者疗效有限。由β淀粉样蛋白（Aβ）组成的老年斑导致神经细胞凋亡是AD主要分子病理特征。我们的前期动物实验发现低强度808 nm激光照射（LLI808）可抑制线粒体分裂和促进融合，增强线粒体活性和减轻氧化损伤，改善大鼠脑内由Aβ1-42引起的神经退行性病变，但相关的细胞信号通路及作用机制尚不清楚。在此基础上，本项目通过Aβ1-42处理神经样分化PC12细胞建立AD细胞模型，给予LLI808照射，显微观察细胞形态变化，通过基因敲除/过表达和RNA-Seq等方法检测相关基因和蛋白质表达情况，揭示LLI808通过增强线粒体活性来抑制Aβ诱导细胞凋亡的信号转导机制，为LLI808线粒体机制的进一步阐述、AD光疗在临床推广和AD靶因子药物治疗开发提供理论依据。

防治阿尔茨海默病（AD）的关键是解决神经元丢失的问题。如何阻止神经细胞凋亡，临床尚无有效方法。我们前期动物实验发现，低强度808 nm激光（LLI808）照射能促进海马神经细胞线粒体融合，保持一个有益的线粒体动态平衡，从而抑制了神经细胞凋亡，显著改善AD大鼠的神经退行性病变。但相关的细胞信号通路及作用机制尚不清楚。本项目从体外细胞模型着手，运用基因组学、蛋白质组学的研究方法，发现低强度红光照射可以影响cAMP-PKA-PLC信号转导通路的活性，调控核转录调控相关基因Nrip1、Atf7的表达水平，下调线粒体分裂因子（Mff）的表达、上调线粒体融合蛋白2（Mfn2）的表达，抑制线粒体分裂促其融合，达到抑制氧化损伤诱导的神经样分化大鼠肾上腺嗜铬肿瘤细胞（dPC12细胞）凋亡的光生物调节作用。该研究成果可以为AD光疗在临床的推广和AD的关键靶因子药物治疗开发提供理论依据，同时也对临床干预与细胞凋亡相关的疾病有一定的理论参考价值。