Molecular Mechanisms of Axonal Sprouting and Recovery from Stroke

描述（由申请人提供）：中风是成人残疾的主要原因。然而，中风后确实会发生有限的自发修复和恢复过程。在中风患者中，这种恢复与梗塞周围和相连皮质区的感觉和运动功能的重新映射有关。在非人类灵长类动物和啮齿类动物模型中，中风通过称为轴突发芽的过程诱导这些相同区域形成新的连接。我们最近发现，在小鼠中风模型中，中风后运动和运动前皮质回路中的轴突发芽与运动恢复有因果关系。这些研究确定轴突发芽是促进中风后恢复的重要细胞靶点。中风后轴突发芽的过程包括三个关键步骤， 神经元：中风向邻近的神经元发送信号（触发器），其激活基因表达程序（转录因子），然后神经元通过大脑启动轴突生长（细胞外信号传导或粘附蛋白）。我们最近发现了一个“发芽转录组”的成功发芽神经元周围梗死后中风皮层。当用严格的统计检验分析这个转录组时，与常规基因相关的基因 细胞骨架结构被移除后，一小部分分子与中风后神经元的发芽过程有关。三种分子在萌芽神经元中受到高度调节，与中风后轴突萌芽中的这三个关键细胞步骤有关。生长分化因子10（GDF 10）是一种骨形态发生蛋白，在中风后分泌（潜在触发因素）。bcl 11b是一种转录因子，在萌芽神经元中也被诱导，并且在发育中的大脑中具有促进皮质轴突生长的正常功能。Matrilin-2是一种促进周围神经再生的细胞外基质蛋白，在卒中后皮质出芽神经元中下调。GDF 10、Bcl 11b和matrilin-2在成年人大脑中尚未得到广泛研究，在中风后也未得到研究。初步数据链接这三个分子轴突发芽在体外和体内。这项研究将使用药理学和遗传操作技术来确定这三种分子是否诱导轴突发芽，然后确定活小鼠中运动和感觉地图随时间的变化模式，这些模式与这些分子系统中功能的获得和丧失有关。最后，将确定这些系统中功能的获得和丧失对中风后运动控制和恢复的影响。这种方法使用了一种新的实验平台，详细和结构映射的大脑连接，这些连接的功能生理学的体内映射，以及恢复的行为研究，为“分子映射到行为”的方法，以确认非常有前途的分子靶点中风后神经修复。

DESCRIPTION (provided by applicant): 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. The process of axonal sprouting after stroke involves three key steps for an adult cortical neuron: stroke sends a signal to adjacent neurons (a trigger), which activates a gene expression program (transcription factor), and the neuron then initiates axonal growth through the brain (extracellular signaling or adhesion proteins). We have recently identified a "sprouting transcriptome" of successfully sprouting neurons in peri-infarct cortex after stroke. When this transcriptome is analyzed with stringent statistical testing, and the genes associated with routine cytoskeletal structure removed, a small set of molecules are linked to the process of sprouting in neurons after stroke. Three molecules are highly regulated in sprouting neurons in relationship to these three key cellular steps in post-stroke axonal sprouting. Growth Differentiation Factor 10 (GDF10) is a bone morphogenic protein that is secreted after stroke (potential trigger). Bcl11b is a transcription factor that is also induced in sprouting neurons and has a normal function of promoting cortical axon growth in the developing brain. Matrilin-2 is an extracellular matrix protein that promotes peripheral nerve regeneration and is paradoxically down-regulated in cortical sprouting neurons after stroke. GDF10, Bcl11b and matrilin-2 have not been studied extensively in the adult brain, and have not been studied at all after stroke. Preliminary data links these three molecules to axonal sprouting in vitro and in vivo. The studies in this grant wil use pharmacological and genetic manipulation techniques to determine if these three molecules induce 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 these molecular systems. 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, in vivo mapping of the functional physiology of these connections, and behavioral studies of recovery, for a "molecules to maps to behavior" approach to confirm highly promising molecular targets for post-stroke neural repair.