Transcriptional mechanisms in mast cells underlying immune function and disease

摘要 压力和感染驱动的大脑神经免疫激活在疾病、过敏和 焦虑症、抑郁症等精神疾病。肥大细胞 (MC) 是先天免疫细胞，在 暴露于免疫挑战和压力下，它们会释放预先形成的介质，如组胺、血清素、 调节大脑炎症和生理机能的酶和细胞因子，使它们处于有利的位置 影响大脑功能并驱动对压力和疾病的行为和生理反应。虽然我们知道 MC 的发育和功能很大程度上是由基因转录、遗传和 MC 调控的转录机制仍知之甚少，针对 MC 的方法 治疗感染和压力相关疾病的方法仍然基本上无法实现。我们发现了一种新颖的转录 限制 MC 激活和调节的因子 ΔFosB，我们的初步数据表明缺乏 FosB 的小鼠 MC 中特有的基因在响应急性免疫激活时更容易生病，但显示 总体情绪升高并减少焦虑。因此，我们假设：1）急性 MC 活性受到 FosB 的限制 基因表达作为预防疾病的机制； 2) 慢性压力或免疫激活驱动 ΔFosB 表达改变 MC 动态并促进与精神疾病相关的脆弱性 大脑中的神经炎症。描述 ΔFosB 调节 MC 基因表达的机制 和功能，我们将完成以下目标：1）确定FosB基因表达在MC功能中的作用 使用传统的免疫组织化学结合全新的离体和体内 Ca2 成像 技术； 2) 使用我们缺乏的新型小鼠品系来表征 MC ΔFosB 在生理学和行为中的作用 FosB 基因在 MC 中的表达，并测试对免疫挑战的生理反应和 对压力的行为反应； 3) 使用 RNAseq 确定 MC 中 ΔFosB 的下游基因靶标 在培养的 MC 中进行 CUT & RUN，并采用创新的 TRAP 方法在体内发现 MC 中的基因靶标。在一起， 这些目标将展示与生理学和疾病相关的 MC 调节的新机制，介绍 并验证对活体小鼠 MC 活性研究至关重要的新工具，并发现新的遗传和 MC 中的转录靶标可在药理学上用于治疗从过敏性 对致命感染、抑郁症和其他情绪障碍的反应。

SUMMARY Stress- and infection-driven neuroimmune activation in the brain plays a central role in sickness, allergies, and psychiatric diseases like anxiety and depression. Mast cells (MCs) are innate immune cells rapidly activated upon exposure to immune challenges and stress, and they release preformed mediators such as histamine, serotonin, enzymes, and cytokines that regulate inflammation and physiology in the brain, making them well positioned affect brain function and drive behavioral and physiological responses to stress and sickness. Although we know that MC development and function are largely driven by changes in gene transcription, the genetic and transcriptional mechanisms by which MCs are regulated remain poorly understood, and the means to target MCs to treat infection and stress-related diseases remain largely unavailable. We have uncovered a novel transcription factor that limits MC activation and modulation, ΔFosB, and our preliminary data show that mice lacking the FosB gene specifically in MCs are more vulnerable to sickness in response to acute immune activation but show elevated mood and reduced anxiety overall. Thus, we hypothesize that: 1) acute MC activity is limited by FosB gene expression as a mechanism to prevent sickness; and 2) chronic stress or immune activation drives ΔFosB expression to alter MC dynamics and promote vulnerability to psychiatric diseases associated with neuroinflammation in the brain. To delineate the mechanisms by which ΔFosB regulates MC gene expression and function, we will complete the following aims: 1) Determine the role of FosB gene expression in MC function using traditional immunohistochemistry combined with a completely novel ex vivo and in vivo Ca2+ imaging technique; 2) Characterize the role of MC ΔFosB in physiology and behavior using our novel mouse line lacking FosB gene expression specifically in MCs and testing both physiological response to immune challenge and behavioral response to stress; 3) Determine the downstream gene targets of ΔFosB in MCs using RNAseq and CUT & RUN in cultured MCs and an innovative TRAP approach to uncover gene targets in MCs in vivo. Together, these aims will demonstrate a novel mechanism of MC regulation relevant to physiology and disease, introduce and validate new tools critical for the study of MC activity in the living mouse, and uncover new genetic and transcriptional targets in MCs that could be pharmacologically leveraged to treat conditions ranging from allergic reactions to deadly infections to depression and other mood disorders.