LINGO-1-Fc蛋白对低钾诱导小脑颗粒神经元凋亡的保护作用

髓鞘抑制因子Nogo-A、MAG和OMgp通过共同的受体信号复合物NgR/p75NTR(或者TROY)发挥对中枢神经纤维再生的抑制作用.新近克隆的跨膜蛋白LINGO-1是该信号途径的另一个重要组成成分和调节分子.LINGO-1特异表达于中枢神经系统,神经元上的LINGO-1被证明参与调节中枢神经再生的抑制信号,而少突胶质细胞表达的LINGO-1分子参与负调节少突胶质细胞的髓鞘化过程.为探讨LINGO-1分子在神经元凋亡过程中的作用,利用包含LINGO-1分子胞外段LRR和IgC2结构域的Fc融合蛋白作为功能性拮抗剂,研究LINGO-1对低钾诱导的小脑颗粒神经元凋亡的保护作用.利用成熟的Hoechst标记凋亡细胞的方法,观察到经LINGO-1-Fc蛋白预处理2h能够显著阻止小脑颗粒神经元的凋亡.仅包括LRR结构域的GST-LINGO-1与LINGO-1-Fc蛋白,虽同样具有与颗粒神经元的结合活性,但是GST-LINGO-1不能有效地阻止低钾诱导的细胞凋亡.这些结果提示,LINGO-1-Fc蛋白能够阻止低钾诱导的小脑颗粒神经元凋亡,并且这种作用可能是IgC2结构域依赖的.

LINGO-1-Fc Fusion Protein Prevents Apoptosis of Cerebellar Granule Neurons Induced by Low-potassium

Three myelin proteins, Nogo-A, MAG and OMgp, transduce their neurite-outgrowth inhibitory signal through a common receptor complex: NgR/ p75NTR (or TROY). Recently, LINGO-1 is identified as another essential component and regulator for the Nogo-66 receptor/p75 signaling complex. LINGO-1 is restricted to express in CNS, neuronal LINGO-1 is shown to be involved in the signal transduction from three myelin proteins, and Lingo-1 in oligodendrocyte negatively regulates the differentiation and myelination of oligodendrocyte. To investigate the potential activity of LINGO-1 in neuronal apoptosis, LINGO-1-Fc fusion protein including the extracellular LRR and IgC2 domain, was used as functional antagonist to study its protective effect on low-potassium induced apoptosis of cerebellar granule neurons (CGNs). In judgement of the apoptotic nuclei stained by Hoechst, LINGO-1-Fc pretreatment for 2 h significantly prevents apoptosis of CGNs. Although GST-LINGO-1 protein, including the LRR domain, binds to the CGN cultures in the same way with LINGO-1-Fc, it doesn't prevent the apoptosis of CGNs. These results indicate that LINGO-1-Fc fusion protein prevents low-potassium induced apoptosis of cerebellar granule neurons in certain conditions and this activity is probably IgC2 domain dependent.