Defining the Role of Microglia in the Synaptic Rewiring of the Hypothalamus by Early life Adversity

项目摘要 这一K99/R 00提案将检验一个关键假设，即： 大脑回路受到早期生活逆境的影响，同时为PI提供额外的科学知识。 技术和专业技能，导致她成功的独立职业生涯。 早期生活的逆境可以深刻地影响一个人患上与压力有关的情绪障碍的风险 包括抑郁症，很可能是通过调节底层大脑回路的成熟。我们发现早期生命 暴露在贫困的环境中会引发抑郁症的核心症状（快感缺失）， 通过改变压力敏感神经元的连通性。具体地说，我们发现兴奋性神经元的数量增加， 突触到室旁核的促肾上腺皮质激素释放激素（CRH）表达神经元 下丘脑（PVN）。此外，这些突触的变化足以诱导持久的表观基因组的变化， 关键神经元基因包括Crh的表达。然而，早期生活中的逆境 调节突触的发展和持久性的压力相关的大脑回路仍然未知。 小胶质细胞，大脑的常驻免疫细胞，已经成为突触形成的关键效应子。 连接在发展中的视觉和体感系统。因此，小胶质细胞是有吸引力的候选者， 在塑造与压力相关的下丘脑神经元的连通性方面起着类似的作用。该提案将（1）测试 小胶质细胞调节室旁核CRH表达神经元兴奋性突触数量的假说， 关键的应激反应脑区目标2将检验早期生活逆境影响 小胶质细胞与PVN-CRH神经元及其兴奋性突触的相互作用。最后的目标将采用这两个 假设驱动和数据驱动的方法，以确定逆境的分子机制- 引发了小胶质细胞功能障碍总之，拟议的实验将首次阐明 小胶质细胞在早期生活逆境后大脑回路异常成熟中的作用。 这一建议将大大加强PI的职业发展，并推动她走向职业生涯 目标是成为一个独立的研究机构的研究人员。拟议项目提供 尖端研究技能培训，包括实时双光子成像和四维分析，以及“大数据” 转录组学分析。加州大学欧文分校提供了一个理想的培训环境， 世界著名的发育神经生物学、小胶质细胞/神经免疫学和分子生物学专家。在 此外，UCI还提供了一个鼓励协作与合作的智力环境， 候选人作为科学界成员的成长。事实上，PI将参与旨在 为她的独立做好准备，包括实验室管理，网络，granecraft和 为学术就业市场做准备。总之，这里提出的系统计划将使PI 科学和职业明智的成长和独立，从而很好地定位她获得未来的R 01资金。

PROJECT ABSTRACT This K99/R00 proposal will test a critical hypothesis on the mechanisms by which maturation of brain circuits is impacted by early-life adversity, while providing the PI with additional scientific technologies and professional skills, leading to her successful independent career. Early-life adversity can profoundly impact an individual’s risk for stress-related emotional disorders including depression, likely by modulating the maturation of the underlying brain circuits. We find that early-life exposure to an impoverished environment provokes core symptoms of depression (anhedonia), accompanied by altered connectivity of stress-sensitive neurons. Specifically, we find an increase in the number of excitatory synapses onto corticotropin-releasing hormone (CRH)-expressing neurons in the paraventricular nucleus of the hypothalamus (PVN). Further, these synaptic changes suffice to induce enduring epigenomic changes in the expression of critical neuronal genes including Crh. However, the mechanisms by which early-life adversity modulates synapse development and persistence in stress-related brain circuits remain unknown. Microglia, the brain’s resident immune cells, have emerged as key effectors in the shaping of synaptic connectivity in the developing visual and somatosensory systems. Microglia are thus attractive candidates for playing a similar role in sculpting connectivity of stress-related hypothalamic neurons. This proposal will (1) test the hypothesis that microglia regulate excitatory synapse number on CRH-expressing neurons in the PVN, a key stress-responsive brain region. Aim 2 will test the hypothesis that early-life adversity influences the interactions of microglia with PVN-CRH neurons and their excitatory synapses. The final Aim will employ both hypothesis-driven and data-driven approaches to identify molecular mechanisms underlying adversity- provoked microglial dysfunction. Together, the proposed experiments will, for the first time, elucidate the role of microglia in aberrant maturation of brain circuits following early-life adversity. This proposal will significantly enhance the PI’s career development, and advance her towards her career goal of becoming an independent investigator at a research-focused institution. The proposed project provides training in cutting-edge research skills, including live 2-photon imaging and 4-D analysis, as well as “big-data” analysis of transcriptomics. The University of California-Irvine provides an ideal environment for training, with world-renowned experts in developmental neurobiology, microglia/neuroimmunology and molecular biology. In addition, UCI provides an intellectual environment that encourages collaboration and cooperation, enabling the candidate’s growth as a member of the scientific community. Indeed, the PI will engage in activities designed to prepare her for independence, including training in lab management, networking, grantsmanship, and preparation for the academic job market. In summary, the systematic plan proposed here will enable the PI’s scientific and career-wise growth and independence, thus well-positioning her to attain future R01 funding.