Gαi1/3介导SCF-c-kit通路信号转导促脊髓神经损伤修复作用及机制研究

SCF-c-kit signaling is involved in spine cord neuronal injury recovery. We have identified Gαi1/3 as a novel and key signal molecule in receptor tyrosine kinase (RTK) signaling. Pilot experiment results showed that Gαi1/3 knockout/knockdown significantly inhibited SCF-induced downstream signaling activation. In the Allen's mouse spinal cord injury model, c-kit and Gαi1/3 were over-expressed, which coupled to form a signaling complexe. Forced-expresssion of Gαi3 by injection of adenovirus construct in the spinal cord injured area could improve motor function recovery. We propose that Gαi1/3 mediate SCF-c-kit signal transduction to promote spinal cord neuronal injury recovery. This project will examine expression of SCF, c-kit and Gαi1/3 in spinal cord of the Allen's mice. Research focus will be on the mechanism of Gαi-mediated SCF-c-kit signal transduction, and the mechanism of Gαi-induced spinal cord neuronal survival and dendritic/axon outgrowth. The viral construct of Gαi1/3 will be injected into the spinal cord injury area, in order to study the role of Gαi1/3 in the spine cord neuronal injury in mice. Finally, we will compare the sensitivity of spinal cord injuried mice between wild-type and Gαi1/3 double knockout mice. This study will provide a new target for the treatment of spinal cord neuronal injury.

干细胞因子SCF-c-kit信号参与脊髓神经损伤修复。Gαi1/3是我们证实的受体酪氨酸激酶（RTK）新的关键信号分子。预实验结果显示敲除/敲减Gαi1/3显著抑制SCF诱导的下游信号传导；Allen's小鼠脊髓损伤模型中c-kit及Gαi1/3高表达并耦联形成复合物；脊髓损伤区注射Gαi3过表达腺病毒有助于小鼠运动功能恢复。我们提出Gαi1/3介导SCF-c-kit信号转导，帮助小鼠脊髓神经损伤修复。本项目将系统检测Allen's小鼠脊髓损伤模型损伤区SCF、c-kit、Gαi1/3等表达情况。解析Gαi介导SCF-c-kit信号转导及促脊髓运动神经元存活及树/轴突生长作用和分子机制。运用脊髓损伤区注射病毒载体等方法，在体研究Gαi1/3调控小鼠脊髓神经损伤修复的作用。最后对比观察野生型和Gαi1/3基因敲除小鼠对脊髓损伤敏感性差异。为脊髓神经损伤修复和治疗提供新靶点(Gαi1/3)。

本项目围绕干细胞因子SCF-c-kit信号参与脊髓神经的损伤修复展开相关研究。项目初期证实Gαi1/3是受体酪氨酸激酶（RTK）新的关键信号分子，敲除/敲减Gαi1/3显著抑制SCF下游信号传导，脊髓损伤区c-kit及Gαi1/3高表达，耦联形成蛋白复合物，损伤区注射Gαi1/3过表达腺病毒有助于运动功能恢复，证实Gαi1/3参与SCF作用神经元轴突生长的调控。但脊髓损伤病理机制复杂，除神经元轴突改变外，还有巨噬细胞极化、小胶质细胞炎性反应等，因此团队继续研究Gαi1/3在炎性因子调控免疫细胞反应中的作用机制。结果证实Gαi1/3敲除（DKO）显著抑制IL-4诱导的PI3K-AKT通路、ERK-MAPK通路的活化，过表达Gαi1/3促进M2型细胞极化。同样地，Gαi1/3敲低阻断HMGB1诱导的Akt-mTOR，MAPK-Erk激活，降低小胶质细胞的增殖活化。综上，在本项目研究前期得出结论：Gαi1/3对脊髓损伤后分泌的多种细胞因子（BDNF、SCF、IL-4、HMGB1）下游信号通路起关键作用，Gαi1/3对神经元细胞呈正向作用，提高Gαi1/3表达，促进RTKs与Gαi1/3耦联，有望促进脊髓损伤后神经元的轴突生长。因此在项目研究中期，本团队设计研发RTKs-Gαi1/3信号增强肽Syn3，活化神经元下游信号（Akt-mTOR、Erk-MAPK），促进神经元细胞的轴突生长，增加神经元数量，促进脊髓损伤运动功能恢复。因此在项目研究中期得出结论：Gαi1/3增强子药物Syn3，高效促进RTKs-Gαi1/3耦联，活化神经元细胞下游增殖信号，有望应用于脊髓损伤治疗。在项目研究后期，为提高药物的功效，团队设计多种生物功能材料（金纳米棒生物材料、血细胞膜材料、白蛋白纳米材料等），证实结合生物功能材料有效递送药物，实现脊柱脊髓损伤相关疾病的治疗修复。综上所述，我们在本课题研究中发现：Gαi1/3参与调控多种细胞因子对神经元细胞轴突生长、巨噬细胞极化、小胶质细胞激活等信号通路；增强RTKs-Gαi1/3的耦联提高神经元细胞的轴突生长，“Gαi1/3增强子”Syn3有效提高脊髓神经元细胞的数量，促进运动功能恢复；联用生物功能材料有望提高Syn3的治疗效果，促进脊髓损伤的运动功能恢复。