Calcium signaling in neuronal navigation

描述（由申请人提供）：定向神经元导航，包括细胞体迁移和生长锥寻路，是建立精确布线的神经网络的先决条件，并且对于大脑的正常功能至关重要。越来越多的证据表明，生长锥导航和神经元细胞导航在早期发展有许多相似的功能，包括响应一组类似的指导线索，激活特定的细胞内信号级联和细胞骨架的变化定向运动。例如，netrin-1，一种进化上保守的长距离生长锥导向因子，在发育过程中对神经回路形成至关重要，也指导皮层神经元和嗅觉神经元的细胞迁移。Ca 2+信号已经成为介导生长锥和细胞对许多指导线索（包括netrin-1）的反应的核心参与者。然而，定向神经元导航的Ca 2+信号的时空调节还不清楚。虽然神经网络的形成主要发生在出生前和出生后早期，新的神经元不断产生的神经祖细胞和整合到现有的神经网络中的离散区域的成年哺乳动物的大脑，包括脑室下区（SVZ）的侧脑室和海马的颗粒下区（SGZ）。成人脑中的神经发育概括了主要的神经发育里程碑，从神经祖细胞的增殖和命运特化到神经元形态发生、细胞迁移、轴突和树突导向以及神经元后代的突触形成。由于成体神经发生的环境与胚胎神经发生的环境明显不同，因此神经发育的分子机制是否保守尚不清楚。我们的长期目标是了解分子和细胞机制，决定了运动和方向性的发展神经元响应于指导线索，并制定治疗策略，以促进再生损伤或疾病后的人类中枢神经系统（CNS）。在目前的项目中，我们的目标是了解在早期神经发育过程中和成年大脑中Ca 2+信号传导在调节神经元导航中的作用，其中心假设是TRPC、STIM 1和奥赖蛋白合作设定生长锥和神经元定向运动的基础和诱导Ca 2+水平，使用体外生长锥转动测定、免疫细胞化学、多光子共聚焦显微镜和电生理学。我们的研究将为神经元导航的分子机制提供重要信息，并可能导致新的见解，神经元导航过程是否在成熟的大脑中受到类似或差异的调节，这对于制定促进再生的策略非常重要。 公共卫生相关性：该项目旨在了解STIM 1、TRPC和奥赖蛋白在胚胎发育和成人大脑中调节钙变化以指导生长锥引导和神经元细胞迁移的功能作用。这些研究的发现可能会导致新的策略，以功能性地取代受损或丢失的神经元，并促进损伤或退行性神经疾病后的内源性修复。

DESCRIPTION (provided by applicant): Directed neuronal navigation, including both cell body migration and growth cone path-finding, is a pre- requisite for the establishment of the precisely wired neural network and is essential for the proper function of the brain. Accumulating evidence suggests that growth cone navigation and neuronal cell navigation during early development share many similar features, including responses to a similar set of guidance cues, activation of specific intracellular signaling cascades and cytoskeletal changes for directed movements. For example, netrin-1, an evolutionally conserved long-range growth cone guidance cue essential for neural circuit formation during development, also directs cell migration of cortical neurons and olfactory neurons. Ca2+ signaling has emerged as a central player in mediating growth cone and cellular responses to many guidance cues, including netrin-1. The spatial and temporal regulation of Ca2+ signaling underlying directed neuronal navigation, however, is not well understood. While neural network formation occurs predominantly during the prenatal and early postnatal periods, new neurons are continuously generated from neural progenitors and integrated into the existing neural network in discrete regions of adult mammalian brain, including the subventricular zone (SVZ) of the lateral ventricle and the subgranular zone (SGZ) of the hippocampus. Neurodevelopment in the adult brain recapitulates the major neural developmental milestones, from proliferation and fate specification of neural progenitors, to neuronal morphogenesis, cell migration, axon and dendritic guidance, and synapse formation by neuronal progeny. Because adult neurogenesis occurs in a significantly different environment from embryonic neurogenesis, whether the molecular mechanisms underlying neural development are conserved is not clear. Our long-term goal is to understand the molecular and cellular mechanisms that determine the motility and directionality of developing neurons in response to guidance cues and to develop therapeutic strategies to promote regeneration after injury or diseases of the human central nervous system (CNS). In the current project, we aim to understand the role of Ca2+ signaling in regulating neuronal navigation during early neural development and in the adult brain with the central hypothesis that TRPC, STIM1 and Orai proteins co-operate to set the basal and induced Ca2+ levels for directed motility of growth cones and neurons, using a combination of in vitro growth cone turning assay, immunocytochemistry, multi-photon confocal microscopy and electrophysiology. Our study will provide important information on the molecular mechanisms underlying neuronal navigation and may lead to novel insights as to whether neuronal navigation processes are similarly or differentially regulated in the mature brain, which is important for developing strategies in promoting regeneration. PUBLIC HEALTH RELEVANCE: The project aims at understanding the functional roles of STIM1, TRPC and Orai proteins in regulating the calcium changes for directed growth cone guidance and neuronal cell migration during embryonic development and in the adult brain. Findings from these studies may lead to novel strategies to functionally replace damaged or lost neurons and to promote endogenous repair after injury or degenerative neurological disease.