Regulation of mammalian brain development by p21-activated kinases

我的研究计划的长期目标是了解大脑发育和功能背后的分子机制。为此，我们一直在鉴定和表征一系列对神经元的增殖、存活、迁移、形态形成和成熟至关重要的分子，这些分子是一系列高度调控的过程，对正常的脑生长、神经回路的形成和功能至关重要。在这一应用中，我们将研究p21激活的激酶(PAK)在小鼠皮质发育过程中调节神经元迁移和形态发生的作用和潜在机制。PAK是一个丝氨酸/苏氨酸蛋白激酶家族，在多种信号转导和细胞过程中发挥重要作用，特别是在肌动蛋白细胞骨架的调控中。然而，PAK在哺乳动物大脑发育中的作用仍然难以捉摸。我们发现，缺乏PAK1和PAK3(PAK家族蛋白的主要大脑亚型)的基因敲除小鼠，大脑大小显著减小，皮质组织改变，神经元数量和形态减少。此外，在这些小鼠中，PAKS下游靶标的活性也发生了显著变化。PAKS下游靶标是肌动蛋白结合蛋白cofilin，也是肌动蛋白重组的有效调节因子。因此，我们假设PAK1/3通过肌动蛋白依赖的神经元迁移和形态发生来调节皮质发育。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、生化分析和电生理分析。这一应用的结果将揭示PAK信号调节皮质和神经元发育的体内作用和潜在机制。由于皮质畸形和帕金森病都与许多神经和精神障碍密切相关，这一建议也将为这些疾病的发病机制和治疗提供新的见解。

The long-term goal of my research program is to understand the molecular mechanisms underlying brain development and function. To this end, we have been identifying and characterizing a series 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. In this application, we will investigate the role and underlying mechanisms of p21-activated kinases (PAKs) in the regulation of neuronal migration and morphogenesis during mouse cortical development. PAKs are a family of serine/threonine protein kinases known to be important for multiple signaling and cellular processes, particularly in the regulation of the actin cytoskeleton. However, the role of PAKs in mammalian brain development remains elusive. We have discovered that the knockout mice lacking PAK1 and PAK3, the predominant brain isoforms of the PAK family proteins, are dramatically reduced in brain size with altered cortical organization, reduced neuronal number and morphology. In addition, the activity of a downstream target of PAKs, the actin-binding protein cofilin and a potent regulator of actin reorganization, is also significant altered in these mice. We therefore hypothesize that PAK1/3 regulate cortical development via actin-dependent neuronal migration and morphogenesis. To address this hypothesis, we will employ multiple techniques, including mouse genetics, immunohistochemistry, imaging, biochemical assays and electrophysiological analysis. The results from this application will reveal the in vivo role and underlying mechanisms by which PAK signaling regulates cortical and neuronal development. 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.