Glucocorticoid-regulated transcription networks in macrophage biology

巨噬细胞(MΦ)驱动的炎症是脂肪组织代谢性疾病发病机制的核心。 肝脏、血管内皮和皮肤。然而，MΦ在其个体发育、表观基因组、 转录本和功能。事实上，“瘦”脂肪组织M2-样M-Φ具有抗炎、促进脂肪酸作用 氧化并使脂肪细胞对胰岛素敏感。在皮肤中，动态平衡组织修复MΦ是必不可少的 损伤的反应者和有缺陷的伤口愈合是代谢紊乱的显著共病。信号用于 动态平衡MΦ编程(如白细胞介素4和糖皮质激素[GC])通过同源转录启动 因子(STAT6和GC核受体[GR])基因表达级联，最终汇聚到 主控调节因子(KLF)4，激活许多M2特异性基因。相反，类M1 炎症性MΦ具有核因子κB的转录特征，并过度产生 慢性炎症(肿瘤坏死因子、白介素1、诱导型一氧化氮合酶、β)。尽管M1/M2失衡与新陈代谢密切相关 功能障碍和伤口愈合受损，特定的表观基因组和转录网络 不同M2群体的动态平衡极化仍不清楚。事实上，只有有限的数据存在于 KLF4作为转录因子发挥作用的机制，几乎没有关于其全基因组分布或 在单独的M2子集编程中的作用。出乎意料的是，我们发现一种核受体辅因子-- GR-相互作用蛋白(GRIP)1-作为KLF4的辅助激活剂促进小鼠骨骼M2极化 骨髓来源的M-Φ。鉴于KLF4本身是一个GR靶点，GRIP1可以调节M2的多层次整合 当MΦ同时遇到不同的极化信号，例如GC和IL4时，体内的转录程序。 这个应用程序的目的是理解表观基因组学、转录组学和更高的顺序 动态型M-Φ染色质相互作用的体内外研究我们的中心假设是GC和IL4 在稳态MΦ中创建部分重叠但不同的染色质环境，并通过充当 对于GR和KLF4，GRIP1促进了M2-1的生理相关功能收敛 就像体内的转录程序一样。我们的具体目标是：1)剖析GRIP1对GR的全球贡献 和KLF4增强子的形成以及通过全基因组方法对核心M2样转录程序的影响 在体外GC和IL_4极化的M-Φ中；2)评估GRIP1缺失对表型和代谢的影响 动态型M-Φ体外特性及其对表观基因组和转录能力的影响 编程，并支持体内组织修复；3)绘制第一张高阶染色质与GRIP1- 动态平衡MΦ中依赖的增强子-启动子相互作用，并鉴定其机制决定因素 GRIP1：KLF4串音。该项目的成功完成将产生对 全球染色质相互作用、核心转录组以及依赖GRIP1的分子机制 MΦ的动态平衡编程，与炎症性MΦ激活不同，仍未明确。

Macrophage (MΦ)-driven inflammation is central to the pathogenesis of metabolic disease in adipose tissue, liver, vascular endothelium and the skin. However, MΦ are extremely diverse in their ontogeny, epigenomes, transcriptomes and function. Indeed, `lean' adipose tissue M2-like MΦ are anti-inflammatory, facilitate fatty acid oxidation and sensitize adipocytes to insulin. In the skin, homeostatic tissue-repairing MΦ are essential responders to damage, and defective wound healing is a striking comorbidity of metabolic disorder. Signals for homeostatic MΦ programming (e.g., interleukin [IL]4 and glucocorticoids [GC]) initiate via cognate transcription factors (STAT6 and the GC nuclear receptor [GR]) gene expression cascades that ultimately converge upon the `master regulator' kruppel-like factor (KLF)4 that activates many M2-specific genes. Conversely, M1-like inflammatory MΦ bear the transcriptional signature of nuclear factor (NF)κB and overproduce mediators of chronic inflammation (TNF, IL1β, iNOS, Ccl2). Although an M1/M2 imbalance is strongly linked to metabolic dysfunction and impaired wound healing, the specific epigenomic and transcriptional networks underlying homeostatic polarization of different M2 populations remain obscure. In fact, only limited data exist on the mechanisms of KLF4 function as a transcription factor, and virtually none on its genome-wide distribution or role in programming individual M2 subsets. Unexpectedly, we discovered that a nuclear receptor cofactor – the GR-interacting protein (GRIP)1 – serves as a coactivator for KLF4 facilitating M2 polarization of mouse bone marrow-derived MΦ. Given that Klf4 itself is a GR target, GRIP1 could mediate the multi-level integration of M2 transcription programs in vivo when MΦ encounter distinct polarizing signals, e.g., GC and IL4, simultaneously. The objective of this application is to understand the epigenomics, transcriptomics and higher order chromatin interactions of homeostatic MΦ in vitro and in vivo. Our central hypothesis is that GC and IL4 create partially overlapping yet distinct chromatin environments in homeostatic MΦ, and that by serving as a shared cofactor for GR and KLF4, GRIP1 facilitates the physiologically relevant functional convergence of M2- like transcription programs in vivo. Our Specific Aims are to: 1) Dissect the global contribution of GRIP1 to GR and KLF4 enhancer formation and to the core M2-like transcription program through genome-wide approaches in GC- and IL4-polarized MΦ ex vivo; 2) Assess the impact of GRIP1 loss on the phenotypic and metabolic properties of homeostatic MΦ ex vivo and on their ability to undergo epigenomic and transcriptional programming, and support tissue repair in vivo; 3) Chart the first map of higher-order chromatin and GRIP1- dependent enhancer-promoter interactions in homeostatic MΦ, and identify the mechanistic determinants of the GRIP1:KLF4 cross-talk. The successful completion of this project will yield a comprehensive analysis of global chromatin interactions, the core transcriptome as well as GRIP1-dependent molecular mechanisms of homeostatic programming of MΦ which, unlike inflammatory MΦ activation, remains poorly defined.