MED1 Regulates BMP/TGF-β in Endothelium: Implication for Pulmonary Hypertension

Abstract

BACKGROUND: 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 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 ( ERG ), and TGFBR2 (TGF-β receptor 2) and their involvement in the PH. METHODS: High-throughput screening involving data from RNA-seq, MED1 ChIP-seq, H3K27ac ChIP-seq, KLF4 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 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- MED1 −/− ) were used to study the PH-protective effect of MED1. RESULTS: 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- MED1 −/− mice showed PH susceptibility. In contrast, MED1 overexpression mitigated the PH phenotype in rodents. CONCLUSIONS: 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.

CD4+ T-Cell Legumain Deficiency Attenuates Hypertensive Damage via Preservation of TRAF6

“…Supplemental Materials & Methods Tables S1, S2, S4, and S5 Figures S1-S28 Data Set S1 References 11,12,20,21,40,61,[63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80]…”

The role ofSMURFsin non‐cancerous diseases

“…Furthermore, a prevalent pathological observation in PAH is the diminished signaling of BMP, and the potential enhancement of this pathway could yield therapeutic advantages. 95 The BMP/SMAD signaling is negatively regulated by SMURF2, 36 yet there is limited research on the role of SMURF2 in pulmonary hypertension. It is plausible that SMURF2 functions similar to SMURF1 in the pathophysiological progression of PAH, warranting further investigation.…”

Endothelial FIS1 DeSUMOylation Protects Against Hypoxic Pulmonary Hypertension

“…The SENP1 expression pattern was validated in HPAECs under either a long-term hypoxic exposure (1% O 2 ) over 5 days (Figure S1I through S1K) or an extreme oxygen concentration lower than 0.5% O 2 in 48 hours (Figure S1L through S1N), whereas reduced SENP1 was also imaged by immunofluorescence microscopy with fragmented mitochondria on long-term hypoxia of 1% O 2 for 5 days (Figure 1L and 1M). According to the settings of sustained hypoxia treatment as described in previous reports, [42][43][44][45][46] we employed 1% O 2 for 48 hours as short-term hypoxia exposure and 1% O 2 for 5 days as long-term hypoxia exposure, in the following analyses in vitro. Consistently, the tubular structure of mitochondria in HPAECs began to be disrupted after short-term hypoxic exposure and turned to be excessively fragmented on long-term hypoxia (Figure 1N), with quantification of mitochondrial morphology by FF, AR (Figure 1O through 1Q), and the degree of mitochondrial fragmentation by mitochondrial fragmentation count (Figure 1R).…”