Intrinsic control of early microglia development and its impact on neural cell development

许多神经发育障碍的起源，如自闭症和精神分裂症，都与基因有关 以及环境因素。越来越多的证据表明，免疫反应是 遗传和环境因素对这些疾病的影响，强调了 脑发育中的神经免疫相互作用。小胶质细胞是中枢神经中的常驻免疫细胞。 对成年和衰老大脑的动态平衡以及对大脑突触的修剪至关重要。 发育中的后脑。在神经发生开始的时候，小胶质细胞出现在早期胚胎的大脑中， 在基因表达和形态上经历了一系列变化，导致了时间和空间上的 在整个开发过程中的异质性。最近的研究表明，胚胎小胶质细胞是否会影响 通过基因或化学方法消融小胶质细胞或导致全身性 母体免疫激活。这些研究表明，早期胚胎的小胶质细胞可能在 神经发生和神经元迁移以及轴突生长和引导。然而，这些早期的角色并不是 众所周知，由于各种限制，与后来的发育作用相比，包括：1)细胞消融 无法解决某些小胶质细胞类型或状态在大脑发育中的具体贡献，排除了 阐明分子机制，以及2)母体免疫激活不仅影响小胶质细胞，而且可以 也直接影响神经细胞。此外，之前的一些研究显示，在 小胶质细胞消融后神经发生的改变。 为了克服这些限制，我们开发并分析了突变小鼠，在这些小鼠中，锌指 转录因子SALL1在小胶质细胞中被特异性地敲除。我们通过免疫染色和 形态分析表明，在没有SALL1的情况下，小胶质细胞的发育受到固有的干扰 胚胎大脑，神经发生和早期轴突发育正在进行中。在拟议的探索性报告中 研究项目，我们计划对SALL1突变小鼠的小胶质细胞进行单细胞RNA测序 和野生型对照，并鉴定改变的小胶质细胞亚群以及改变的基因表达 在每个小胶质细胞亚群中。接下来，我们将分析早期神经发育的各个关键方面 SALL1突变小鼠，并确定小胶质细胞发育改变是否影响这些事件。通过 结合这两项研究的结果，我们期望开发一个有效的假说来解释 涉及不同小胶质细胞群体的早期神经免疫相互作用的分子基础。在漫长的岁月里 这个项目将对我们理解小胶质细胞如何被破坏提供重要的积极影响。 发育有助于神经发育障碍和新靶向的后续发展 治疗这些疾病的干预措施。

Origins of many neurodevelopmental disorders such as autism and schizophrenia encompass both genetic and environmental factors. Accumulating evidence indicates that immune response is a key underlying component of both genetic and environmental contributions to these disorders, highlighting the importance of neuroimmune interactions in brain development. Microglia are resident immune cells in the central nervous system and are critical for the homeostasis of adult and aging brains as well as for the pruning of synapses in developing postnatal brains. Microglia appear in early embryonic brains at the time when neurogenesis starts, and undergo a series of changes in gene expression and morphology resulting in temporal and spatial heterogeneity throughout development. Recent studies have addressed whether embryonic microglia influence early neurodevelopmental events by either genetically or chemically ablating microglia or causing systemic maternal immune activation. These studies suggest that early embryonic microglia might have roles in neurogenesis and neuronal migration as well as axon growth and guidance. However, these early roles are not as well understood compared with later developmental roles due to various limitations including: 1) cell ablation cannot address the specific contribution of certain microglia types or states in developing brains, precluding the elucidation of molecular mechanisms, and 2) maternal immune activation not only affects microglia but can also directly impact neural cells. In addition, some of the previous studies show conflicting results on the alteration of neurogenesis in response to microglia ablation. To overcome these limitations, we have developed and analyzed mutant mice in which the zinc finger transcription factor SALL1 is knocked out specifically in microglia. We found by immunostaining and morphology analysis that microglia development is intrinsically perturbed in the absence of SALL1 starting in embryonic brains where neurogenesis and early axon development are underway. In the proposed exploratory research project, we plan to perform single-cell RNA sequencing comparing microglia from Sall1 mutant mice and wild-type controls, and identify the altered microglia subpopulations as well as altered gene expression within each microglia subpopulation. We will next analyze various key aspects early neural development in Sall1 mutant mice and determine whether altered development of microglia impacts these events. By combining the results of these two studies, we expect to develop a valid hypothesis that would explain the molecular underpinnings of early neuroimmune interactions involving diverse microglia populations. In the long term, this project will provide an important positive impact on our understanding of how disrupted microglia development contributes to neurodevelopmental disorders and on subsequent development of novel targeted interventions to treat these disorders.