miR-21/MACF1信号轴在机体运动改善TBI所致认知障碍过程中的机制研究

Traumatic brain injury (TBI) is a major public health concern and results in high rates of death and disability worldwide. Most of moderate-to-severe TBI patients suffer from long-lasting cognitive deficits, including deficits in memory capacity, attention, executive functions, and general cognitive intelligence which affects both patients and families. The mechanisms which mediate TBI-induced cognitive impairment are poorly understood in spite of tremendous efforts. Previous researches have demonstrated that physical exercise is one of the most effective methods to improve TBI-induced cognitive impairment. Our preliminary data illustrated that physical exercise 1) improved TBI-induced learning deficits;2) alleviated the atrophy of the injured brain hemisphere; and 3) promoted the synaptic formation and axon extension. It has been demonstrated that miR-21/MACF1 signaling axis plays an important role in the improvement of physical exercise on TBI-induced cognitive deficits through high throughput screening. In the following study, yeast two hybrid screening, co-immunoprecipitation and whole cell recording of patch clamp will be employed to explore the detailed mechanisms by which miR-21/MACF1 signaling axis regulates the neuronal axon elongation and synaptic plasticity. Furthermore, the function of miR-21/MACF1 signaling axis and its downstream effectors in the improvement of physical exercise on TBI-induced cognitive deficits will also be explored via behavior tests.

外伤性颅脑损伤（TBI）发生率和死亡率的不断升高，不仅降低患者的生存质量，也加重了家庭和社会的负担。研究显示，机体运动是改善TBI所致认知障碍最有效的方法之一。前期工作中发现，机体运动改善了由TBI导致的学习障碍，抑制了损伤侧大脑半球的萎缩，明显促进了突触的形成和神经元轴突的延伸能力。经高通量筛选及荧光素酶等实验，申请者证实miR-21/MACF1信号轴介导了机体运动改善TBI引起的学习障碍。在本项目中，申请者拟通过酵母双杂交、免疫共沉淀及神经电生理等技术手段，详细研究miR-21/MACF1信号轴调控神经元轴突延伸及突触可塑性的具体分子机制和信号通路；通过动物行为学，验证miR-21/MACF1信号轴及其下游效应分子在机体运动改善TBI所致认知障碍过程中的功能和作用。本研究有望对机体运动保护TBI后认知损伤的机制提供新的理论依据，为将来更好制定TBI患者的诊疗及康复策略尽一份绵薄之力。

外伤性颅脑损伤（TBI）发生率和死亡率的不断升高，不仅降低患者的生存质量，也加重了家庭和社会的负担。研究显示，机体运动是改善TBI所致认知障碍最有效的方法之一。前期工作中发现，机体运动改善了由TBI导致的学习障碍，抑制了损伤侧大脑半球的萎缩，明显促进了突触的形成和神经元轴突的延伸能力。经高通量筛选及荧光素酶等实验，申请者证实miR-21/MACF1信号轴介导了机体运动改善TBI引起的学习障碍。在本项目中，申请者拟通过酵母双杂交、免疫共沉淀及神经电生理等技术手段，详细研究miR-21/MACF1信号轴调控神经元轴突延伸及突触可塑性的具体分子机制和信号通路；通过动物行为学，拟验证miR-21/MACF1信号轴及其下游效应分子在机体运动改善TBI所致认知障碍过程中的功能和作用。研究发现，通过受控皮质冲击（controlled cortical impact，CCI）进行外伤性颅脑损伤模型造模；通过定位注射miR-21 antagomiR以及对应的阴性对照miR-21 antagomiR NC抑制miR-21在脑组织中的表达；机体运动对TBI模型小鼠创伤后的脑组织损伤和认知缺陷有明显的恢复作用，而miR-21的表达抑制对TBI模型机体运动后的脑组织损伤和学习能力改善具有促进作用；机体运动促进了小鼠TBI后海马区神经元的功能恢复，miR-21的表达抑制对运动促进小鼠TBI后海马神经元的功能恢复具有促进作用；miR-21直接靶向MACF1，并负向调节MACF1的表达；miR-21通过靶向MACF1参与运动促进小鼠TBI后海马神经元的功能恢复； MACF1与GSK3B之间具有直接结合关系；miR-21通过靶向MACF1调控GSK3B/β-catenin通路参与小鼠TBI后海马神经元的功能恢复。研究中miR-21/MACF1信号轴未发现与之前预想下游分子发生作用，其原因可能与啮齿类动物模型的选择有关。结合临床预测数据，课题组开展了以与人类基因组高度重合的树鼩为模型的相关研究，已取得较大进展，未来研究将基于此模型继续开展认知功能损伤机制的探索。