Transcriptional mechanisms in mast cells underlying immune function and disease

总结 压力和感染驱动的大脑神经免疫激活在疾病，过敏和 精神疾病如焦虑和抑郁。肥大细胞（MC）是先天性免疫细胞，在免疫后迅速激活。 暴露于免疫挑战和压力，并且它们释放预先形成的介质，例如组胺，血清素， 酶和细胞因子，调节大脑中的炎症和生理，使它们能够很好地定位 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的发育和功能在很大程度上是由基因转录、遗传和 MCs的转录调控机制仍然知之甚少，靶向MCs的方法 治疗感染和与压力有关的疾病的药物仍然基本上得不到。我们发现了一种新的转录 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 MCs中特异性的基因更容易对急性免疫激活做出反应， 情绪提升焦虑减少因此，我们假设：1）急性MC活动受到FosB的限制 基因表达作为预防疾病的机制; 2）慢性应激或免疫激活驱动ΔFosB 表达改变MC动力学和促进易感性相关的精神疾病 大脑中的神经炎症阐明ΔFosB调控MC基因表达的机制 本研究的主要目的是：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Ca 2+成像， 2）利用我们的新的小鼠品系缺失MC ΔFosB， FosB基因在MCs中的特异性表达，并测试对免疫攻击的生理反应， 对应激的行为反应; 3）使用RNAseq确定MCs中ΔFosB的下游基因靶标， CUT & RUN在培养的MCs和创新的TRAP方法，以发现基因靶点在MC体内。在一起， 这些目标将展示一种与生理和疾病相关的MC调节的新机制， 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 MCs中的转录靶点，可以被利用来治疗从过敏性 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.