Department of Cardiology, First Affiliated Hospital of Xi'an Jiaotong University, China (C.W., Y.X., J.Z., J.D., H.W., L.B., J.S., Z.-Y.).
Cardiovascular Research Center, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, China (C.W., Y.X., J.Z., J.D., S.C., L.B., F.H., A.S.).
Circ Res. 2022 Oct 28;131(10):828-841. doi: 10.1161/CIRCRESAHA.122.321532. Epub 2022 Oct 14.
Dysregulated BMP (bone morphogenetic protein) or TGF-β (transforming growth factor beta) signaling pathways are imperative in idiopathic and familial pulmonary arterial hypertension (PAH) as well as experimental pulmonary hypertension (PH) in rodent models. MED1 (mediator complex subunit 1) is a key transcriptional co-activator and KLF4 (Krüppel-like factor 4) is a master transcription factor in endothelium. However, MED1 and KLF4 epigenetic and transcriptional regulations of the BMP/TGF-β axes in pulmonary endothelium and their dysregulations leading to PAH remain elusive. We investigate the MED1/KLF4 co-regulation of the BMP/TGF-β axes in endothelium by studying the epigenetic regulation of BMPR2 (BMP receptor type II), ETS-related gene (), and TGFBR2 (TGF-β receptor 2) and their involvement in the PH.
High-throughput screening involving data from RNA-seq, MED1 ChIP-seq, H3K27ac ChIP-seq, ATAC-seq, and high-throughput chromosome conformation capture together with in silico computations were used to explore the epigenetic and transcriptional regulation of BMPR2, ERG, and TGFBR2 by MED1 and KLF4. In vitro experiments with cultured pulmonary arterial endothelial cells (ECs) and bulk assays were used to validate results from these in silico analyses. Lung tissue from patients with idiopathic PAH, animals with experimental PH, and mice with endothelial ablation of MED1 (EC-) were used to study the PH-protective effect of MED1.
Levels of MED1 were decreased in lung tissue or pulmonary arterial endothelial cells from idiopathic PAH patients and rodent PH models. Mechanistically, MED1 acted synergistically with KLF4 to transactivate BMPR2, ERG, and TGFBR2 via chromatin remodeling and enhancer-promoter interactions. EC- mice showed PH susceptibility. In contrast, MED1 overexpression mitigated the PH phenotype in rodents.
A homeostatic regulation of BMPR2, ERG, and TGFBR2 in ECs by MED1 synergistic with KLF4 is essential for the normal function of the pulmonary endothelium. Dysregulation of MED1 and the resulting impairment of the BMP/TGF-β signaling is implicated in the disease progression of PAH in humans and PH in rodent models.
在特发性和家族性肺动脉高压（PAH）以及啮齿动物模型的实验性肺动脉高压（PH）中，BMP（骨形态发生蛋白）或 TGF-β（转化生长因子β）信号通路的失调是至关重要的。MED1（中介复合物亚基 1）是关键的转录共激活因子，KLF4（Krüppel 样因子 4）是内皮细胞中的主转录因子。然而，MED1 和 KLF4 在肺内皮细胞中对 BMP/TGF-β 轴的表观遗传和转录调控及其导致 PAH 的失调仍然难以捉摸。我们通过研究 BMPR2（BMP 受体 2）、ETS 相关基因（）和 TGFBR2（TGF-β 受体 2）的 BMP/TGF-β 轴的表观遗传调控以及它们在 PH 中的参与，来研究 MED1/KLF4 对内皮细胞中 BMP/TGF-β 轴的共同调控。我们使用涉及 RNA-seq、MED1 ChIP-seq、H3K27ac ChIP-seq、ATAC-seq 和高通量染色体构象捕获的数据的高通量筛选以及计算进行了研究，以探索 MED1 和 KLF4 对 BMPR2、ERG 和 TGFBR2 的表观遗传和转录调控。我们使用培养的肺动脉内皮细胞（ECs）的体外实验和批量测定来验证这些计算分析的结果。我们使用特发性 PAH 患者、实验性 PH 动物和内皮细胞 MED1 缺失（EC-）的小鼠的肺组织来研究 MED1 的 PH 保护作用。
在特发性 PAH 患者和啮齿动物 PH 模型的肺组织或肺动脉内皮细胞中，MED1 的水平降低。从机制上讲，MED1 通过染色质重塑和增强子-启动子相互作用与 KLF4 协同作用，转激活 BMPR2、ERG 和 TGFBR2。EC-小鼠表现出 PH 易感性。相比之下，MED1 的过表达减轻了啮齿动物的 PH 表型。
MED1 与 KLF4 协同作用，对 ECs 中 BMPR2、ERG 和 TGFBR2 的稳态调节对于肺内皮细胞的正常功能至关重要。MED1 的失调以及由此导致的 BMP/TGF-β 信号转导受损与人类 PAH 和啮齿动物模型中 PH 的疾病进展有关。
