Chromatin remodeling, and a persistent histone 3 lysine 27 acetylation (H3K27ac) in particular, are associated with a sustained inflammatory response of synovial fibroblasts (SF) in rheumatoid arthritis (RA). Here we investigated individual functions of the writers of H3K27ac marks, the homologues histone acetyl transferases (HAT) CBP and p300, in controlling the constitutive and inflammatory gene expression in RA SF. We applied a silencing strategy, followed by RNA-sequencing and pathway analysis, complemented with the treatment of SF with inhibitors targeting the HAT (C646) or bromo domains (I-CBP) of CBP and p300. We showed that CBP and p300 undertook overlapping and, in particular at gene levels, distinct regulatory functions in SF. p300 is the major HAT for H3K27ac in SF and regulated more diverse pathways than CBP. Whereas both factors regulated genes associated with extracellular matrix remodeling, adhesion and proliferation, p300 specifically controlled developmental genes associated with limb development. Silencing of CBP specifically down regulated the TNF-induced expression of interferon-signature genes. In contrast, silencing of p300 resulted in anti- and pro-inflammatory effects. Integration of data sets derived from RNA-sequencing and chromatin immunoprecipitation sequencing for H3K27ac revealed that changes in gene expression after CBP or p300 silencing could be only partially explained by changes in levels of H3K27ac. Inhibition of CBP/p300 using HAT and bromo domain inhibitors strongly mirrored effects obtained by silencing of p300, including anti- and pro-inflammatory effects, indicating that such inhibitors are not sufficient to be used as anti-inflammatory drugs.

染色质重塑，尤其是持续的组蛋白 3 赖氨酸 27 乙酰化 (H3K27ac)，与类风湿性关节炎 (RA) 中滑膜成纤维细胞 (SF) 的持续炎症反应有关。在这里，我们研究了 H3K27ac 标记、同系物组蛋白乙酰转移酶 (HAT) CBP 和 p300 在控制 RA SF 中的组成型和炎症基因表达中的个体功能。我们应用了一种沉默策略，然后是 RNA 测序和通路分析，辅以针对 CBP 和 p300 的 HAT (C646) 或溴结构域 (I-CBP) 的抑制剂治疗 SF。我们发现 CBP 和 p300 在 SF 中具有重叠，特别是在基因水平上，具有不同的调节功能。p300 是 SF 中 H3K27ac 的主要 HAT，并且比 CBP 调节更多样化的途径。虽然这两个因素都调节与细胞外基质重塑、粘附和增殖相关的基因，但 p300 专门控制与肢体发育相关的发育基因。CBP 的沉默特异性地下调了 TNF 诱导的干扰素特征基因的表达。相反，p300 的沉默导致抗炎和促炎作用。整合来自 H3K27ac 的 RNA 测序和染色质免疫沉淀测序的数据集显示，CBP 或 p300 沉默后基因表达的变化只能部分通过 H3K27ac 水平的变化来解释。使用 HAT 和溴结构域抑制剂抑制 CBP/p300 强烈反映了通过沉默 p300 获得的效果，包括抗炎和促炎作用，