Localized translation of cytoskeletal proteins in axonal morphogenesis

描述（由申请人提供）：轴突侧支的形成是神经元与多个目标神经元进行突触接触的基础，从而产生复杂的神经元网络。在神经系统损伤的情况下，轴突侧支的形成可能有有益或有害的影响，这取决于受影响的电路。侧枝也受多种疾病状态的影响。然而，侧枝的细胞机制只是最低限度的了解。本文提出的初步数据首次揭示了分支诱导信号神经生长因子驱动轴突内细胞骨架蛋白的合成，并在侧支的形成中发挥作用。重要的是，初步数据还表明，神经生长因子诱导轴突侧枝分支需要轴突蛋白的合成。尽管最近的研究已经揭示了一组针对轴突的mrna，但轴突mrna在轴突翻译中的功能作用仍然知之甚少。该建议的主要目的是确定单个细胞骨架蛋白的轴突合成在轴突侧支形成中的作用。通过将PI （Gallo博士；神经元细胞骨架细胞生物学）和Co-I （Twiss博士；轴突蛋白质合成）的专业知识联系起来，该项目

DESCRIPTION (provided by applicant): The formation of axon collateral branches underlies the ability of neurons to make synaptic contacts with multiple target neurons and thus give rise to complex neuronal networks. In the context of nervous system injury, the formation of axon collateral branches can have either beneficial or undesired effects depending on the affected circuitry. Collateral branches are also affected by a variety of disease states. However, the cellular mechanisms of collateral branching are only minimally understood. The preliminary data presented in this proposal unveils for the first time that the branch-inducing signal nerve growth factor drives the intra-axonal synthesis of cytoskeletal proteins with roles in the formation of collateral branches. Importantly, the preliminary data also demonstrate that axonal protein synthesis is required for the induction of axon collateral branching by nerve growth factor. Although recent studies have revealed a large set of mRNAs targeted to axons, the functional roles of the axonal translation of axonal mRNAs remains minimally understood. The main aim of the proposal is to determine the roles of the axonal synthesis of individual cytoskeletal proteins in the formation of axon collateral branches. By bridging the expertise of the PI (Dr. Gallo; neuronal cytoskeletal cell biology) and the Co-I (Dr. Twiss; axonal protein synthesis), the project provides the unique opportunity to uncover a new aspect of the mechanism of axon branching and aims to directly link the axonal synthesis of specific cytoskeletal proteins to the regulation f the dynamics of the axonal cytoskeleton. Through the joint expertise of the PI and Co-I, the project takes a multi-pronged in vivo and in vitro approach to address the main Aims. Collateral branching is affected by nervous system injury and disease. However, the ability to manipulate branching in a therapeutic context is mostly lacking. The project has the potential to lead to strategies for the regulation of axon branching by targeting specific axonal mRNA species in the context of neuronal injury and disease. The reagents developed for use in the project (e.g., cell permeable tools to selectively inhibit the axonal translation of individual mRNA species) have the potential for translation to animal model system of collateral branching in future directions o the project. The work we propose will serve as the foundation for these long term goals by determining the relevant mRNA targets through the elucidation of their roles in branching.