How do neurons recognize self from non-self?

神经元如何识别自我和非自我？

• 批准号: 10246025
• 负责人: Daniele Canzio
• 金额: $ 145.35万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10246025
• 关键词: 3-Dimensional; Architecture; Bar Codes; Biochemical; Brain; Brain Diseases; Cells; Complex; DNA; Ensure; Exons; Gene Cluster; Gene Expression Regulation; Generations; Genes; Genetic; Genetic Transcription; Genome; Genomics; Individual; Lead; Mammals; Mediating; Messenger RNA; Modeling; Neurons; Neurosciences; Process; Property; Protein Isoforms; RNA; RNA Processing; RNA Splicing; Reaction; Role; Schizophrenia; Surface; Testing; Trans-Splicing; Work; autism spectrum disorder; base; design; essays; in vivo; mRNA Precursor; nervous system disorder; neural circuit; novel; technological innovation; tool

PROJECT SUMMARY This essay aims to understand a fundamental property of neurons: their ability to self-recognize and self- avoid. Self-avoidance is an essential aspect of a neuron's function as it ensures that branches from the same cell minimize their overlap while maximizing their interactions with branches from other cells. In mammals, at the core of this process is the generation of sufficient Protocadherin (Pcdh) protein isoform diversity such that essentially every neuron in the brain is differentially barcoded at its surface and therefore appears different to other neurons. The generation of Pcdh protein isoform diversity requires complex mechanisms of Pcdh transcriptional and pre-mRNA splicing such that distinct Pcdh mRNA molecules - bearing a different 5' end (variable exon) but an identical 3' end (constant exons) - are expressed in individual cells. Understanding how different Pcdh mRNA molecules are produced represents a long-term mystery in the field of neuroscience. Answering this fundamental mystery is key in illuminating the process of neuronal self-avoidance and represents the first essential step toward dissecting how dysregulation of this Pcdh mediated self-avoidance can lead to severe neurological disorders, such as for instance autism spectrum disorder and schizophrenia. Despite their critical function in the brain, however, limited progress has been made in understanding how Pcdh mRNAs are transcribed and properly spliced as general models of gene expression regulation have failed to recapitulate this complex mechanism and as the tools required to study it directly in vivo have lagged behind. In this proposal, we aim to (i) test a paradigm-shifting hypothesis of Pcdh RNA transcription and splicing based on alternative trans-splicing of variable and constant exons encoded in tandem on the same DNA strand - a mechanism that we propose to be regulated by the 3D genome topology of the Pcdh locus - and (ii) design technological innovations that will allow precise manipulation of the Pcdh gene cluster in vivo to test our hypothesis directly in neurons. These studies have the potential to illuminate the complex mechanism of the generation of Pcdh isoform diversity and its role in neuronal self-avoidance and wiring of healthy and disease brains. The findings from these studies are also poised to open up a new class of regulatory mechanisms of RNA processing reactions, previously unobserved and uncharacterized in mammals but that we speculate are utilized by cells to overcome challenging problems of pre-mRNA splicing associated with complex gene architectures.

项目概要 本文旨在了解神经元的一个基本属性：它们自我识别和自我识别的能力。 避免。自我回避是神经元功能的一个重要方面，因为它确保来自同一神经元的分支 细胞最小化它们的重叠，同时最大化它们与其他细胞的分支的相互作用。在哺乳动物中，在 该过程的核心是产生足够的原钙粘蛋白 (Pcdh) 蛋白亚型多样性，使得 本质上，大脑中的每个神经元在其表面都有不同的条形码，因此看起来与 其他神经元。 Pcdh 蛋白异构体多样性的产生需要 Pcdh 的复杂机制 转录和前 mRNA 剪接使得不同的 Pcdh mRNA 分子具有不同的 5' 末端 （可变外显子）但具有相同的 3' 末端（恒定外显子） - 在单个细胞中表达。了解如何 不同的 Pcdh mRNA 分子的产生是神经科学领域的一个长期谜团。 回答这个基本谜团是阐明神经元自我回避和自我回避过程的关键。 代表了剖析这种 Pcdh 失调如何介导自我回避的第一步 可能导致严重的神经系统疾病，例如自闭症谱系障碍和精神分裂症。 然而，尽管它们在大脑中发挥着至关重要的作用，但在理解它们如何发挥作用方面却取得了有限的进展。 Pcdh mRNA 的转录和正确剪接与基因表达调控的一般模型一样 未能概括这种复杂的机制，并且直接在体内研究它所需的工具已经滞后 在后面。在本提案中，我们的目标是 (i) 测试 Pcdh RNA 转录的范式转换假设和 基于可变外显子和恒定外显子的选择性反式剪接的剪接，所述可变外显子和恒定外显子在同一外显子上串联编码 DNA 链 - 我们建议由 Pcdh 基因座的 3D 基因组拓扑调节的机制 - (ii) 设计技术创新，以实现体内 Pcdh 基因簇的精确操作 直接在神经元中检验我们的假设。这些研究有可能阐明复杂的问题 Pcdh异构体多样性的产生机制及其在神经元自我回避和连接中的作用 健康和疾病的大脑。这些研究的结果也有望开辟一类新的 RNA 加工反应的调节机制，以前未观察到且未表征 哺乳动物，但我们推测细胞利用它们来克服前 mRNA 剪接的挑战性问题 与复杂的基因结构有关。