Investigating Microglia Colonization and Differentiation in the Embryonic Brain

研究胚胎脑中小胶质细胞的定植和分化

• 批准号: 10678046
• 负责人: Camden Hoover
• 金额: $ 4.77万
• 依托单位: UNIVERSITY OF NOTRE DAME
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-05-02 至 2026-05-01
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10678046
• 关键词: Anatomy; Biological; Biology; Brain; Cells; Central Nervous System; Characteristics; Cues; Development; Disease; Embryo; Endocytosis; Gene Transfer Techniques; Glial Differentiation; Goals; Health; Homeostasis; Human; Image; Immune; Immunity; Infiltration; Injury; Investigation; Knowledge; Label; Learning; Left; Lymphangiogenesis; Lymphatic; Lymphatic Endothelial Cells; Maps; Microglia; Modeling; Molecular; Molecular Profiling; Mus; Myelogenous; Myelopoiesis; Nature; Neurodevelopmental Disorder; Neurons; Occupations; PUVA Photochemotherapy; Pericytes; Pharmaceutical Preparations; Play; Population; Positioning Attribute; Pregnancy; Process; Proteins; Role; Source; Testing; Transgenic Organisms; Travel; Venous; Work; Yolk Sac; Zebrafish; brain parenchyma; cell type; glial cell development; in vivo; lymphatic vasculature; lymphatic vessel; mannose receptor; migration; molecular dynamics; nervous system development; network architecture; neuronal circuitry; novel; optogenetics; progenitor; receptor; response; response to injury; tool

ABSTRACT Microglia are the resident immune cells of the Central Nervous System (CNS). They are positioned at the center of brain development and function by playing crucial roles in neuronal network architecture and homeostatic surveillance. Unlike other CNS-resident cells, microglia originate outside the brain, specifically in the embryonic yolk sac (YS). Before microglia can serve their crucial functions, they must first migrate to and infiltrate the developing brain. The cellular and molecular dynamics governing this process are not fully understood, and what we do know is based on YS- derived microglia. However, cre/lox fate mapping studies only map ~30% of all mouse microglia to the YS. This suggests additional sources and populations of microglia could exist. This has been confirmed in zebrafish, where microglia have additional, non-YS origins. The discovery of additional microglia populations leaves us with even less understanding of how microglial precursors seed the brain, especially given that what we do know is from YS-derived microglia only. To begin to fill this critical gap, we investigated the microglia that seed the embryonic brain. Because microglia seeding the brain is a highly dynamic process, we utilized timelapse imaging in zebrafish to watch the cells live. We identified an undescribed cell in the brain that expresses canonical microglia markers, clears debris, and expands in injury. These microglia-like cells are labeled with Mannose Receptor C, type 1a (mrc1a) and colonize the brain earlier than known microglia precursors. mrc1a+ microglia are dependent on the mrc1a+ lymphatic vessels sitting just outside the CNS boundary. These mrc1a+ cells are located within the brain parenchyma and do not associate with vessels or the brain-border, suggesting they’re not macrophages, perivascular cells, or brain lymphatic endothelial cells. Despite our discovery of this early-infiltrating population, the dynamics of how this mrc1a+ population colonizes the brain and expands as microglia are unknown. The implication of mrc1a+ brain-border lymphatics in these processes is also undetermined. The goal of the proposed study is to investigate the cellular and molecular characteristics of a novel, mrc1a+ microglia subpopulation as it colonizes, expands, and differentiates in the developing brain. I will accomplish this by using a combination of in vivo imagine, optogenetic tools, and photoactivatable drugs to carry out the following aims: 1. Determine if brain-border lymphatic vessels contribute microglial progenitors to the developing brain. 2. Characterize the molecular profile of mrc1a+ cells as they differentiate into microglia. This work has the potential to impact a broad spectrum of fields including basic neurodevelopmental biology, neurodevelopmental disorder and disease, glial biology, and CNS homeostasis by investigating the fundamental dynamics behind early microglial precursors as they infiltrate the developing brain, expand, and turn on canonical microglia markers.

抽象的 小胶质细胞是中枢神经系统（CNS）的居民免疫细胞。它们位于 通过在神经元网络架构和稳态监视中扮演至关重要的角色，大脑发育和功能。 与其他CNS居民细胞不同，小胶质细胞起源于大脑外部，特别是在胚胎蛋黄（YS）中。 在小胶质细胞可以发挥其关键功能之前，它们必须首先迁移到发育中的大脑并浸润。这 尚未完全了解有关此过程的细胞和分子动力学，我们所知道的是基于ys- 衍生的小胶质细胞。但是，CRE/LOX脂肪图研究仅将所有小鼠小胶质细胞的30​​％映射到YS。这 建议可能存在小胶质细胞的其他来源和种群。这已在斑马鱼中得到证实 小胶质细胞具有额外的非基本起源。发现其他小胶质细胞的发现使我们的发现更少 了解小胶质细胞如何使大脑种子种子，特别是考虑到我们所知道的是ys衍生的 仅小胶质细胞。为了开始填补这一关键的空白，我们研究了播种胚胎大脑的小胶质细胞。因为 大脑播种的小胶质细胞是一个高度动态的过程，我们利用斑马鱼中的时间幻想成像观看细胞 居住。我们确定了大脑中未描述的细胞，该细胞表达了规范的小胶质细胞标记，清除碎片和 扩大伤害。这些小胶质细胞样细胞用甘露糖受体C，1A型（MRC1A）标记并定居 大脑早于已知的小胶质细胞前体。 MRC1A+小胶质细胞取决于MRC1A+淋巴管 就在CNS边界外。这些MRC1A+细胞位于脑实质内，不与 血管或脑海，表明它们不是巨噬细胞，血管周围细胞或脑淋巴内皮 细胞。尽管我们发现了这种早期浸入的人群，但这种MRC1A+种群如何定居的动态 大脑并扩展，因为小胶质细胞是未知的。 MRC1A+大脑淋巴机在这些过程中的含义 也没有确定。拟议的研究的目的是研究细胞和分子特征 在一个新颖的MRC1A+小胶质细胞亚群中，它在发育中的大脑中膨胀，扩展和区分。我 将通过使用体内想象力，光遗传学工具和光活化药物的组合来实现这一目标 以下目的：1。确定脑海淋巴管是否会造成小胶质祖细胞 发展大脑。 2。表征MRC1A+细胞分化为小胶质细胞时的分子谱。这项工作 有可能影响广泛领域，包括基本神经发育生物学，神经发育 通过研究早期背后的基本动力学，疾病与疾病，神经胶质生物学和中枢神经系统稳态 小胶质细胞前体浸润发育中的大脑，扩展并打开规范的小胶质细胞标记。