Inhibition of RUNX1 blocks the differentiation of lung fibroblasts to myofibroblasts

Abstract

Pathological fibrosis contributes to progression of various diseases, for which the therapeutic options are limited. Idiopathic pulmonary fibrosis (IPF) is one such progressive and fatal interstitial fibrotic disease that is often characterized by excessive accumulation of extracellular matrix (ECM) proteins leading to stiff lung tissue and impaired gas exchange. However, the molecular mechanisms underlying IPF progression remain largely unknown. In this study, we determined the role of Runt‐related transcription factor 1 (RUNX1), an evolutionarily conserved transcription factor, in the differentiation of human lung fibroblasts (HLFs) in vitro and in an animal model of bleomycin (BLM)‐induced lung fibrosis. We observed that the expression of RUNX1 was significantly increased in the lungs of BLM‐injected mice as compared to saline‐treated mice. Furthermore, HLFs stimulated with transforming growth factor β (TGF‐β) showed significantly higher RUNX1 expression at both mRNA and protein levels, and compartmentalization in the nucleus. Inhibition of RUNX1 in HLFs (using siRNA) showed a significant reduction in the differentiation of fibroblasts into myofibroblasts as evidenced by reduced expression of alpha‐smooth muscle actin (α‐SMA), TGF‐β and ECM proteins such as fibronectin 1 (FN1), and collagen 1A1 (COL1A1). Mechanistic studies revealed that the increased expression of RUNX1 in TGF‐β‐stimulated lung fibroblasts is due to enhanced mRNA stability of RUNX1 through selective interaction with the RNA‐binding profibrotic protein, human antigen R (HuR). Collectively, our data demonstrate that increased expression of RUNX1 augments processes involved in lung fibrosis including the differentiation of fibroblasts into collagen‐synthesizing myofibroblasts. Our study suggests that targeting RUNX1 could limit the progression of organ fibrosis in diseases characterized by abnormal collagen deposition.

Lung injury epigenetically primes mesenchyme for amplified activation upon re-injury

“…Our finding that Runx1 is a potent regulator of mesenchymal fibrogenic function is consistent with prior reports of Runx1 regulating scar deposition and tissue fibrosis (Koth et al , 2020; Lin et al , 2020; O’Hare et al , 2021), including a recent report demonstrating Runx1 regulating lung mesenchymal cell activation in vitro (Dubey et al , 2022). Our multi-modal analyses revealed Runx1 as both a transcriptional and epigenetic regulator of Col1a2+ cell activation suggesting its role as a pioneer transcription factor (Zaret and Carroll, 2011; Hass et al , 2021) in the lung Col1a2+ cell lineage.…”

Neonatal hyperoxia induces sex-dependent pulmonary cellular and transcriptomic changes in an experimental mouse model of bronchopulmonary dysplasia

“…The copyright holder for this preprint (which this version posted July 14, 2022. ; https://doi.org/10.1101/2022.07.12.499826 doi: bioRxiv preprint these cells might differentiate into collagen-synthesizing myofibroblasts, and contribute to the fibrotic response seen in HOX and BPD 97 . EC induce differentiation and maturation of mural cells via NOTCH3 98,99 , whose expression was decreased in mural cells in HOX.…”

“…We also identified a new subcluster of DIF in HOX, iDIF, in which expression of DIF marker genes was reduced, but TGFB downstream genes were upregulated. Incidentally, upregulation of Runx1 and suppression of Pparg in iDiF also suggest these cells might differentiate into collagen-synthesizing myofibroblasts, and contribute to the fibrotic response seen in HOX and BPD 97 . EC induce differentiation and maturation of mural cells via NOTCH3 98,99 , whose expression was decreased in mural cells in HOX.…”

Genomic, Transcriptomic, and Proteomic Depiction of Induced Pluripotent Stem Cells–Derived Smooth Muscle Cells As Emerging Cellular Models for Arterial Diseases

“…RUNX1 is known to promote extracellular matrix formation, 53 and was identified as involved in myofibroblast differentiation and proliferation in various contexts. [54][55][56] Despite these differences, we do not find a specific enrichment of binding sites for transcription factors known for their involvement in VSMC phenotypic switching among R-SMCs or TP-SMCs, such as SRF, NFκB, or KLF factors, 57 suggesting these cellular models…”