Regulation of cortical circuit formation by subcellular compartmentalization of mRNA translation

项目总结/摘要 大脑皮层和其他投射神经元的轴突投射比它们的细胞体长103-105倍 直径与精致的精度。生长锥（GCs）是一种特殊的亚细胞区室， 引导和目标衍生的信号，并进行亚型特定的程序，以确保适当的电路和突触 阵因为GC从细胞体延伸得太远，需要几个小时到几天才能通过轴突将分子发送到它们 运输，GC必须是“半自主”的。本地翻译已经被提出作为本地控制的机制， 生长锥的功能，但在体内的本地翻译的mRNA的类型和多样性在很大程度上是未知的。更广泛地说， 神经元中的翻译调节可能是正确建立和维持长距离转录的关键机制。 电路多发性神经发育（例如：脆性X综合征）和神经退行性疾病（例如：ALS/FTD）是 由RNA结合蛋白的突变引起，这些突变直接和间接地破坏了RNA加工的几个方面， 最终导致翻译输出的改变我的项目涉及翻译调控如何有助于 利用我们新开发的低输入核糖体开发亚型身份和皮层回路形成 分析方法：1）比较翻译输出并鉴定胞体中差异翻译的mRNA 在多个特定的皮质投射神经元亚型之间; 2）分析胼胝体中局部翻译的完整景观 投射神经元（CPN）GC，以识别在GC中特异性局部翻译的候选调节因子; 3） 功能研究新的，选择本地GC翻译的候选人在胼胝体投射神经元电路形成。 该项目对两种亚型在翻译上的差异进行了相对全面的体内研究， GCs中的局部翻译及其机制。生成的数据和探索的概念将提供一个深刻而严谨的 理解神经亚型之间的翻译调节多样性和区别的基础， 在电路发育过程中在GC中局部翻译的mRNA类别。除了严格调查独特的 远端神经元亚细胞中回路形成、RNA运输和翻译调控的交叉点生物学 车厢，它也有大量的

Project Summary/Abstract Cerebral cortex and other projection neurons extend axonal projections 103-105 times longer than their cell body diameters with exquisite precision. Growth cones (GCs) are specialized subcellular compartments that interpret axon guidance and target-derived signals, and carry out subtype-specific programs to ensure appropriate circuit and synapse formation. Because GCs extend so far from cell bodies that it takes hours to days to send molecules to them via axonal transport, GCs must be “semi-autonomous”. Local translation has been proposed as a mechanism for local control of growth cone function, but the types and diversity of locally translated mRNAs in vivo is largely unknown. More broadly, translational regulation in neurons is likely a crucial mechanism for properly establishing and maintaining long-range circuitry. Multiple neurodevelopmental (ex: Fragile X-Syndrome), and neurodegenerative (ex: ALS/FTD) diseases are caused by mutations in RNA binding proteins that both directly and indirectly disrupt several aspects of RNA processing, and culminate in altered translational output. My project addresses how translational regulation contributes to the development of subtype identity and cortical circuit formation by employing our newly-developed, low-input ribosome profiling approach to: 1) compare translational outputs and identify mRNAs in the somata that are differentially translated between multiple specific cortical projection neuron subtypes; 2) analyze the full landscape of local translation in callosal projection neuron (CPN) GCs to identify candidate regulators that are specifically locally translated in GCs; 3) functionally investigate novel, select locally GC-translated candidates in callosal projection neuron circuit formation. This project undertakes a relatively comprehensive, in vivo investigation of both subtype differences in translation, and local translation and its mechanisms in GCs. The data generated and concepts explored will provide a deep and rigorous foundation for understanding translational regulatory diversity and distinctions between neural subtypes, and the categories of mRNAs locally translated in GCs during circuit development. Beyond rigorously investigating the unique biology at the intersection of circuit formation, RNA trafficking, and translational regulation in distal neuronal subcellular compartments, it also has substantial