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

项目摘要 这项K99/R00提案将检验一项关键假说，即人胚胎成熟的机制 大脑回路受到早期逆境的影响，同时为PI提供了额外的科学研究 技术和专业技能，使她的独立职业生涯取得成功。 早年的逆境可能会深刻地影响个人患压力相关情绪障碍的风险 包括抑郁症，很可能是通过调节潜在大脑回路的成熟来实现的。我们发现早期生命 暴露在贫穷的环境中会引发抑郁症(快感缺乏症)的核心症状，并伴有 通过改变应激敏感神经元的连接性。具体地说，我们发现兴奋的次数增加了 丘脑室旁核促肾上腺皮质激素释放激素(CRH)阳性神经元的突触 下丘脑(PVN)。此外，这些突触变化足以在脑内诱发持久的表观基因组变化。 包括CRH在内的关键神经基因的表达。然而，早期生活中的逆境 调节突触发育和压力相关大脑回路中的持久性仍不清楚。 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者 发展中的视觉和体感系统的连通性。因此，小胶质细胞是很有吸引力的候选细胞 在塑造应激相关下丘脑神经元的连通性方面起着类似的作用。这项建议将(1)检验 小胶质细胞调节下丘脑室旁核CRH阳性神经元兴奋性突触数目的假说 关键的应激反应脑区。目标2将检验这一假设，即早期生活中的逆境影响 小胶质细胞与PVN-CRH神经元及其兴奋性突触的相互作用。最终目标将同时使用这两个 假说驱动和数据驱动的方法来确定逆境背后的分子机制- 引发了小胶质细胞功能障碍。总之，拟议中的实验将第一次阐明 小胶质细胞在早年逆境后脑回路异常成熟中的作用。 这项提议将显著促进私家侦探的职业发展，并推动她走向自己的职业生涯 目标是成为一家专注于研究的机构的独立调查员。拟议的项目提供 尖端研究技能培训，包括实时双光子成像和4-D分析，以及“大数据” 转录本的分析。加州大学欧文分校提供了理想的培训环境， 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……里面 此外，UCI提供了一个鼓励协作和合作的智力环境，使 候选人作为科学界一员的成长。事实上，国际和平协会将参与设计的活动 为她的独立做好准备，包括实验室管理、网络、资质和 为学术就业市场做准备。总而言之，这里提出的系统计划将使PI能够 科学和事业上的成长和独立，从而为她获得未来的R01资金做好了充分的准备。

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.