Molecular Mechanisms of Axonal Sprouting and Recovery from Stroke

描述(申请人提供)：中风是导致成人残疾的主要原因。然而，中风后确实会发生一个有限和自发的修复和恢复过程。在中风患者中，这种恢复与梗塞周围和连接的皮质区域的感觉和运动功能的重新定位有关。在非人类灵长类动物和啮齿动物模型中，中风通过一种称为轴突萌发的过程，在这些相同的区域诱导新的连接形成。我们最近已经证明，在中风的小鼠模型中，中风后运动和运动前皮质环路中轴突的萌发与运动恢复有因果关系。这些研究表明，轴突萌发是促进中风后恢复的重要细胞靶点。卒中后轴突萌发的过程涉及成人皮质的三个关键步骤 神经元：中风向邻近的神经元发送信号(触发器)，激活基因表达程序(转录因子)，然后神经元通过大脑(细胞外信号或黏附蛋白)启动轴突生长。我们最近发现了一个“发芽转录组”，该转录组成功地在中风后的梗死灶周围皮质中萌发神经元。当用严格的统计测试分析这个转录组时，与常规相关的基因 去除细胞骨架结构后，一小部分分子与中风后神经元的萌发过程有关。与中风后轴突萌发的这三个关键细胞步骤有关的发芽神经元中，有三个分子受到高度调控。生长分化因子10(GDF10)是中风后分泌的一种骨形态发生蛋白(潜在触发物)。Bcl11b是一种转录因子，也可以在萌发的神经元中诱导，并具有促进发育中大脑皮质轴突生长的正常功能。Matrlin-2是一种促进周围神经再生的细胞外基质蛋白，在中风后皮质萌发的神经元中表达下调，这是自相矛盾的。GDF10、Bcl11b和matrlin-2在成人大脑中还没有得到广泛的研究，在中风后也根本没有研究过。初步数据表明，这三种分子与体外和体内的轴突萌发有关。这项拨款中的研究将使用药理学和遗传操作技术来确定这三个分子是否会诱导轴突萌发，然后确定随着时间的推移，活着的小鼠的运动和感觉图的模式，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运动控制和中风后恢复的影响。这种方法使用了一个新的实验平台，包括大脑连接的详细和结构映射，这些连接的功能生理学的活体映射，以及恢复的行为研究，以实现分子到行为的映射，以确定中风后神经修复的非常有希望的分子靶点。

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.