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 像焦虑和抑郁这样的精神疾病。肥大细胞(MC)是一种先天免疫细胞，在 暴露在免疫挑战和压力下，它们会释放预先形成的介质，如组胺、5-羟色胺、 调节大脑中炎症和生理的酶和细胞因子，使它们处于有利的位置 影响大脑功能，推动对压力和疾病的行为和生理反应。尽管我们知道 MC的发育和功能在很大程度上是由基因转录、遗传和 调控MC的转录机制仍然知之甚少，靶向MC的手段 用于治疗感染和压力相关疾病的药物在很大程度上仍然不可用。我们发现了一份新的抄本 限制MC激活和调节的因子ΔFosB，我们的初步数据显示，缺乏FosB的小鼠 MC中特有的基因在急性免疫激活时更容易患病，但显示出 情绪高涨，整体焦虑程度降低。因此，我们假设：1)急性MC活动受FosB的限制 基因表达作为一种预防疾病的机制；以及2)慢性应激或免疫激活推动ΔFosB 表达以改变MC动态并增加与以下相关的精神疾病的易感性 大脑中的神经炎症。ΔFosB调控MC基因表达的机制研究 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体内外钙离子成像 技术；2)利用我们的新小鼠品系缺失来表征MCΔFosB在生理和行为中的作用 FosB基因在MC中的特异性表达以及检测对免疫攻击的生理反应和 应激行为反应；3)用RNAseq和Δ确定MCs中FosB下游的基因靶点 在培养的MC中切割和运行，以及一种创新的陷阱方法，以揭示体内MC中的基因靶点。一起， 这些目的将展示一种与生理和疾病相关的MC调节的新机制，介绍 并验证对研究活着的小鼠MC活动至关重要的新工具，并发现新的遗传和 MC中的转录靶点，可以在药物上用于治疗过敏等各种疾病 对抑郁症和其他情绪障碍的致命感染的反应。

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.