α-Chimaerin在缺血性脑卒中轴突出芽和功能修复的作用和机制研究

Stroke is the leading cause of adult disability. However, a limited and spontaneous process of repair and recovery does occur after stroke. In stroke patients this recovery is associated with re-mapping of sensory and motor functions in peri-infarct and connected cortical areas. In non-human primate and rodent models, stroke induces new connections to form in these same areas, by a process termed axonal sprouting. We have recently shown that in a mouse model of stroke, axonal sprouting in motor and premotor cortical circuits after stroke is causally associated with motor recovery. These studies identify axonal sprouting as an important cellular target in promoting enhanced recovery after stroke. We have recently identified a "sprouting transcriptome" of successfully sprouting neurons in peri-infarct cortex after stroke. α-Chimaerin is a transcription factor that is significantly induced in sprouting neurons and has not been studied at all after stroke. Preliminary data links α-Chimaerin to axonal sprouting in vitro and in vivo. The studies in this grant will use pharmacological and genetic manipulation techniques to determine if the α-Chimaerin molecule inhibits axonal sprouting, and then determine the patterns of motor and sensory maps in the living mouse over time that are associated with gain and loss of function in the molecular system. Finally, the effect on motor control and recovery after stroke with gain and loss of function in these systems will be determined. This approach uses a novel experimental platform of detailed and structural mapping of brain connections and behavioral studies of recovery, for a "molecules to maps to behavior" approach to confirm a highly promising molecular target for post-stroke neural repair.

缺血性脑卒中是成年人致残的主要原因。卒中周围皮质产生新连接的过程称之为轴突出芽。研究发现在脑卒中模型中，运动区以及运动前区皮质的轴突出芽与功能恢复存在着因果关系，轴突出芽是促进脑卒中功能恢复重要的细胞靶点。近来本项目组揭示了中风周边皮质区域出芽神经元的转录基因组，这些基因中，α-Chimaerin（α-CHN）是我们新近发现的卒中出芽神经元最明显调高的转录因子。目前未见有关在脑卒中α-CHN研究的任何报道。课题组初步的实验表明，α-CHN可抑制大脑皮质神经元的突起生长，限制卒中神经细胞的轴突出芽。本项目将在前期基础上，运用α-CHN功能增益和功能丧失的研究策略，阐述小鼠大脑运动区和感觉区轴突出芽的投射类型，检测卒中周区轴突出芽的生理功能，最终确定脑卒中神经细胞再生修复过程中α-CHN的重要作用和机理。本项目将对脑卒中的治疗提供新的靶点，为脑卒中治疗探索新的道路。

轴突出芽是一个卒中周围皮质（中风周区）产生新连接的过程，并密切参与脑卒中功能恢复。α1-CHN（α1-chimaerin）是我们新近发现的卒中出芽神经元中最明显调高的转录因子之一，α1-CHN同时也是Ephrin-A下游信号通路，调节发育中的神经元连接。我们研究首先揭示了中风小鼠，恒河猴和人脑中风周区皮质神经元中α-CHN的免疫信号表达上调。 体外实验研究证明α1-CHN可通过胶原蛋白介导的蛋白5（CRMP5)和促动素2(Prokr2)信号来抑制小鼠皮质神经元的轴突生长。在体的动物实验显示α1-CHN限制中风周区皮层神经元的树突和突触棘生长。运用功能增益和功能缺失、在体与离体、从分子到细胞再到系统、从形态学到功能学的研究策略，表明α1-CHN可降低中风周区皮层的轴突连接，阻碍中风后的行为恢复。对中风周区皮质神经元的RNA测序显示α1-CHN激活神经元中的semaphorin信号，并诱导轴突和神经发育特定生长的抑制性级联反应。总体而言，α1-CHN直接影响中风后皮层神经元的可塑性和抑制中风周区的轴突发芽。