Regulation of mammalian brain development by p21-activated kinase signaling pathways

职务名称：通过p21激活的激酶信号通路调节哺乳动物大脑发育 ** 本申请是我目前的NSERC发现资助（RGPIN 341498，2012-2017）的更新。我的研究计划的长期目标是了解支配大脑发育和功能的基本机制。为此，我们已经确定了一些分子，是重要的神经元增殖，存活，迁移，形态发生和成熟，一系列的高度调节的过程中，正常的大脑生长，神经回路的形成和功能的关键。与本申请特别相关的是，在我目前的NSERC发现基金（2012-17）的资助下，我们已经证明了缺乏p21激活激酶（PAK）的敲除（KO）小鼠在脑大小，皮质体积，神经元祖细胞分裂和迁移方面发生了改变，PAK是已知对细胞骨架重组很重要的蛋白激酶家族。值得注意的是，这些KO小鼠在LIMK 1和肌动蛋白结合蛋白cofilin的活性方面存在缺陷，这两者都是对肌动蛋白调节重要的PAK的关键靶点。此外，我们发现PAKs可以对内源性大麻素（eCB）系统产生影响，这是胚胎大脑发育各个方面的新兴参与者。这些结果导致了一个假设，PAKs通过协调肌动蛋白重组和eCB信号调节皮质发育。为了解决这一假设，我们将使用多种技术，包括小鼠遗传学，免疫组织化学，成像，生化测定和电生理记录，以实现三个具体目标：** 目标1。通过标记和追踪不同PAK KO小鼠的神经前体细胞，确定PAK 1和3在神经元增殖和迁移中的相对贡献。目标2.通过分析神经元和突触的形态，确定PAK 1和3在出生后早期神经元形态发生和突触成熟中的作用。目标3.通过研究LIMK 1/cofilin和eCB信号传导的作用，阐明PAK 1/3作用的分子机制。**从这个应用程序的结果将揭示在体内的功能和潜在的机制，PAK信号调节皮层和神经元的发育。这反过来又有助于我的长期目标，即了解大脑发育和功能的基本过程。由于皮质畸形和PAK与许多神经和精神障碍密切相关，因此该建议也将为这些疾病的发病机制和治疗提供新的见解。********

Title: Regulation of mammalian brain development by p21-activated kinase signaling pathways******This application is a renewal of my current NSERC discovery grant (RGPIN341498, 2012-2017).******The long-term goal of my research program is to understand the fundamental mechanisms that govern brain development and function. To this end, we have identified a number of molecules that are important for neuronal proliferation, survival, migration, morphogenesis and maturation, a series of highly regulated processes critical for normal brain growth, neural circuit formation and function. With particular relevance to this application and with the funding of my current NSERC discovery grant (2012-17), we have demonstrated that knockout (KO) mice lacking the p21-activated kinases (PAKs), a family of protein kinases known to be important for cytoskeletal reorganization, are altered in brain size, cortical volume, neuronal progenitor cell division and migration. Significantly, these KO mice are defective in the activity of LIM-kinase 1 (LIMK1) and the actin-binding protein cofilin, both of which are key targets of PAKs important for actin regulation. Furthermore, we discovered that PAKs can exert effects on the endocannabinoid (eCB) system, an emerging player in various aspects of embryonic brain development. These results lead to a hypothesis that PAKs regulate cortical development via coordinating actin reorganization and eCB signaling. To address this hypothesis, we will use multiple techniques, including mouse genetics, immunohistochemistry, imaging, biochemical assays and electrophysiological recordings to achieve three specific aims: ******Aim 1. To determine the relative contribution of PAK1 and 3 in neuronal proliferation and migration by labeling and tracking neural progenitor cells in various PAK KO mice. ******Aim 2. To determine the role of PAK1 and 3 in early postnatal neuronal morphogenesis and synaptic maturation by analyzing neuronal and synaptic morphology. ******Aim 3. To elucidate the molecular mechanisms underlying PAK1/3 actions by investigating the role of LIMK1/cofilin and eCB signaling.******The results from this application will reveal the in vivo function and underlying mechanisms by which PAK signaling regulates cortical and neuronal development. This will in turn contribute to my long-term goal to understand the fundamental process governing brain development and function. Since both cortical malformations and PAKs are closely associated with many neurological and mental disorders, this proposal will also provide new insight into the pathogenesis and treatment of these diseases. ********