Patel Amit K, Park Kevin K, Hackam Abigail S
Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
Neuroscience. 2017 Feb 20;343:372-383. doi: 10.1016/j.neuroscience.2016.12.020. Epub 2016 Dec 21.
Adult mammalian CNS axons generally do not regenerate, creating an obstacle to effective repair and recovery after neuronal injury. The canonical Wnt/β-catenin signaling pathway is an essential signal transduction cascade that regulates axon growth and neurite extension in the developing mammalian embryo. In this study, we investigated whether a Wnt/β-catenin signaling activator could be repurposed to induce regeneration in the adult CNS after axonal injury. We used a retinal ganglion cell (RGC) axon crush injury model in a transgenic Wnt reporter mouse, and intravitreal injections were used to deliver Wnt3a or saline to the RGC cell bodies within the retina. Our findings demonstrated that Wnt3a induced Wnt signaling in RGCs and resulted in significant axonal regrowth past the lesion site when measured at two and four weeks post-injury. Furthermore, Wnt3a-injected eyes showed increased survival of RGCs and significantly higher pattern electroretinography (PERG) amplitudes compared to the control. Additionally, Wnt3a-induced axonal regeneration and RGC survival were associated with elevated activation of the transcription factor Stat3, and reducing expression of Stat3 using a conditional Stat3 knock-out mouse line led to diminished Wnt3a-dependent axonal regeneration and RGC survival. Therefore, these findings reveal a novel role for retinal Wnt signaling in axonal regrowth and RGC survival following axonal injury, which may lead to the development of novel therapies for axonal regeneration.
成年哺乳动物的中枢神经系统轴突通常不会再生,这给神经元损伤后的有效修复和恢复造成了障碍。经典的Wnt/β-连环蛋白信号通路是一种重要的信号转导级联反应,在发育中的哺乳动物胚胎中调节轴突生长和神经突延伸。在本研究中,我们调查了一种Wnt/β-连环蛋白信号激活剂是否可被重新利用,以诱导成年中枢神经系统轴突损伤后再生。我们在转基因Wnt报告小鼠中使用视网膜神经节细胞(RGC)轴突挤压损伤模型,并通过玻璃体内注射将Wnt3a或生理盐水递送至视网膜内的RGC细胞体。我们的研究结果表明,Wnt3a在RGC中诱导Wnt信号,并且在损伤后两周和四周测量时,导致损伤部位远端出现显著的轴突再生。此外,与对照组相比,注射Wnt3a的眼睛中RGC的存活率增加,并且图形视网膜电图(PERG)振幅显著更高。此外,Wnt3a诱导的轴突再生和RGC存活与转录因子Stat3的激活增加有关,使用条件性Stat3基因敲除小鼠品系降低Stat3的表达导致Wnt3a依赖性轴突再生和RGC存活减少。因此,这些发现揭示了视网膜Wnt信号在轴突损伤后轴突再生和RGC存活中的新作用,这可能会导致轴突再生新疗法的开发。