神经元极性的建立,涉及轴突规格和外观,对于实现神经元的正确形态至关重要,这对神经元连接和认知功能很重要。细胞外因素,比如Wnts,调节神经元形态的不同方面。特别是,根据具体情况,非规范的Wnt5a对神经突生长表现出不同的影响。因此,Wnt5a在轴突生长和神经元极化中的作用尚不完全清楚.在这项研究中,我们证明了WNT5a,但不是WNT3a,促进分离的小鼠胚胎皮质神经元的轴突生长,并与核心PCP成分协调,刺梨和Vangl.出乎意料的是,外源性Wnt5a诱导的轴突生长依赖于内源性,神经元Wnts,因为使用IWP2和siRNA介导的Porcupine或Wnless抑制Wnt5a诱导的伸长的敲低对Porcupine的化学抑制作用。重要的是,IWP2延迟治疗不能阻断Wnt5a诱导的伸长,这表明内源性Wnts和Wnt5a在神经元极化的特定时间范围内起作用。成纤维细胞条件培养基中的Wnt5a可以与小的细胞外囊泡(sEV)相关联,我们还表明,这些含Wnt5a的sEV主要负责诱导轴突伸长。
The establishment of neuronal polarity, involving axon specification and outgrowth, is critical to achieve the proper morphology of neurons, which is important for neuronal connectivity and cognitive functions. Extracellular factors, such as Wnts, modulate diverse aspects of neuronal morphology. In particular, non-canonical Wnt5a exhibits differential effects on neurite outgrowth depending upon the context. Thus, the role of Wnt5a in axon outgrowth and neuronal polarization is not completely understood. In this study, we demonstrate that Wnt5a, but not Wnt3a, promotes axon outgrowth in dissociated mouse embryonic cortical neurons and does so in coordination with the core PCP components, Prickle and Vangl. Unexpectedly, exogenous Wnt5a-induced axon outgrowth was dependent on endogenous, neuronal Wnts, as the chemical inhibition of Porcupine using the IWP2- and siRNA-mediated knockdown of either Porcupine or Wntless inhibited Wnt5a-induced elongation. Importantly, delayed treatment with IWP2 did not block Wnt5a-induced elongation, suggesting that endogenous Wnts and Wnt5a act during specific timeframes of neuronal polarization. Wnt5a in fibroblast-conditioned media can associate with small extracellular vesicles (sEVs), and we also show that these Wnt5a-containing sEVs are primarily responsible for inducing axon elongation.