Glial cell behavior in the developing visual system

描述（由申请人提供）：尽管神经胶质细胞的发育和功能与脑癌和神经系统修复有着巨大的临床相关性，但在脊椎动物和无脊椎动物神经生物学中却很少受到关注。在发育过程中，胶质细胞的正确定位对于胚胎中枢神经系统和果蝇视觉系统的神经连接的建立至关重要，这就提出了关于在生长轴突到来之前控制胶质细胞增殖和迁移的机制以及它们所提供的控制轴突生长和寻径的线索的重要问题。一般来说，我们对体内控制胶质细胞迁移的信号和机制知之甚少，虽然在果蝇胚胎中已经发现了重要的胶质细胞来源的引导线索及其受体，但它们在视觉系统中似乎都没有发挥主要作用。我们研究了视网膜下胶质细胞的发育过程，这些胶质细胞随着光感受器的逐渐分化而增殖和迁移到发育中的果蝇眼盘，并研究了不同的信号通路在控制胶质细胞行为中的作用。我们发现EGFr对视网膜下胶质细胞迁移具有非常明显的异构体特异性作用，而这种作用不是由典型的Ras-Raf-MAPK途径介导的。本研究旨在开发改进的遗传和实时成像技术，用于研究增殖迁移细胞群，利用它们阐明胶质细胞在体内迁移的机制，并通过识别相关的配体和效应物来剖析EGFr亚型在控制胶质细胞行为的不同方面的作用；最后的目标是使用分层反向遗传方法，包括FACS分选、基因芯片分析和RNA干扰，寻找参与控制神经胶质行为和神经胶质-神经元相互作用的额外rtk和其他受体。因此，该研究的目标是进一步开发和研究遗传系统中神经胶质细胞行为的急需模型，为神经胶质细胞中EGFr功能的新方面提供材料见解，并将分析扩展到EGFr的非规范途径和其他rtk和受体，最终目标是为人类恶性和再生情况的治疗干扰提供新的靶点。

DESCRIPTION (provided by applicant): Despite enormous clinical relevance for brain cancer and nervous system repair, the development and function of glial cells has received relatively little attention in vertebrate and invertebrate neurobiology. During development, the correct positioning of glia is crucial for the establishment of neural connectivity in the CNS of the embryo and the visual system of Drosophila, raising important questions regarding the mechanisms controlling the proliferation and migration of glia prior to the arrival of growing axons and regarding the cues presented by them to control axonal growth and pathfinding. Generally, little is known about the signals and mechanisms that control glial migration in vivo, and while important glia-derived guidance cues and their receptors have been identified in the Drosophila embryo, none of them appear to play a major role in the visual system. We have investigated the development of the subretinal glia, which proliferate and migrate into the developing Drosophila eye disc concomitant with the progressive differentiation of photoreceptors, and examined the role of different signaling pathways in controlling glial cell behavior. We found that the EGFr has a very pronounced, isoform-specific effect on subretinal glial migration that is not mediated by the canonical Ras-Raf-MAPK pathway. The proposed research aims to develop improved genetic and live imaging techniques for studying proliferative migrating cell populations, to use them to illuminate the mechanisms of glial migration in vivo, and to dissect the role of the EGFr isoforms in controlling different aspects of glial behavior by identifying the relevant ligands and effectors; a final aim is to search for additional RTKs and other receptors involved in controling glial behavior and glia-neuron interactions, using a layered reverse genetic approach that employs FACS sorting, GeneChip analysis and RNA interference. The objective of the proposed study is thus to further develop and investigate a much needed model for glial cell behavior in a genetic system, to provide material insights into novel aspects of EGFr function in the glia, and to expand the analysis towards non-canonical pathways of the EGFr and to other RTKs and receptors, with the ultimate goal of providing new targets for therapeutic interference in both malignant and regenerative situations in humans.