Matrix stiffening induces a pathogenic QKI-miR-7-SRSF1 signaling axis in pulmonary arterial endothelial cells

Abstract

Pulmonary arterial hypertension (PAH) refers to a set of heterogeneous vascular diseases defined by elevation of pulmonary arterial pressure (PAP) and pulmonary vascular resistance (PVR), leading to right ventricular (RV) remodeling and often death. Early increases in pulmonary artery stiffness in PAH drive pathogenic alterations of pulmonary arterial endothelial cells (PAECs), leading to vascular remodeling. Dysregulation of microRNAs can drive PAEC dysfunction. However, the role of vascular stiffness in regulating pathogenic microRNAs in PAH is incompletely understood. Here, we demonstrated that extracellular matrix (ECM) stiffening downregulated miR-7 levels in PAECs. The RNA binding protein Quaking (QKI) has been implicated in the biogenesis of miR-7. Correspondingly, we found that ECM stiffness up-regulated QKI, and QKI knockdown led to increased miR-7. Downstream of the QKI-miR-7 axis, the serine and arginine rich splicing factor 1 (SRSF1) was identified as a direct target of miR-7. Correspondingly, SRSF1 was reciprocally up-regulated in PAECs exposed to stiff ECM and was negatively correlated with miR-7. Decreased miR-7 and increased QKI and SRSF1 were observed in lungs from PAH patients and PAH rats exposed to SU5416/hypoxia. Lastly, miR-7 upregulation inhibited human PAEC migration, while forced SRSF1 expression reversed this phenotype, proving that miR-7 depended upon SRSF1 to control migration. In aggregate, these results define the QKI-miR-7-SRSF1 axis as a mechanosensitive mechanism linking pulmonary arterial vascular stiffness to pathogenic endothelial function. These findings emphasize implications relevant to PAH and suggest the potential benefit of developing therapies that target this miRNA-dependent axis in PAH.

Cellular mechanosignaling in pulmonary arterial hypertension

“…In a recent study by Woodcock et al, SuHx rats and lungs from PAH patients showed decreased miR-7 expression (Woodcock et al 2021 ). miR-7 has been reported to regulate serine and arginine-rich splicing factor 1 (SRSF1), which promotes PAEC migration (Woodcock et al 2021 ).…”

“…In a recent study by Woodcock et al, SuHx rats and lungs from PAH patients showed decreased miR-7 expression (Woodcock et al 2021 ). miR-7 has been reported to regulate serine and arginine-rich splicing factor 1 (SRSF1), which promotes PAEC migration (Woodcock et al 2021 ). Therefore, this may be a novel mechanism by which changes in ECM stiffness in PAH regulates pathologic endothelial dysfunction and cell migration.…”

“…Exposure to chronic hypoxia (10% oxygen) for few weeks induces pathologic elevation in pulmonary arterial pressure via PA medial hypertrophy and sustained pulmonary vasoconstriction (Liang et al 2017 ). SuHx in rats, an animal model developed by Taraseviciene-Stewart et al (Taraseviciene-Stewart et al 2001 ), is the model of PAH that most closely recapitulates the pulmonary arterial lesions found in lung tissues from human PAH patients (Woodcock et al 2021 ) and the progressive hemodynamic sequelae. With a single injection of 20 mg/kg of vascular endothelial growth receptor factor inhibitor sugen SU5416 and exposure to chronic hypoxia (10% oxygen) for three weeks, rats show significant pulmonary arterial medial hypertrophy, pulmonary arterial wall thickening and sustained pulmonary vasoconstriction that results in progressively elevated pressures (Nickel et al 2015 ; Woodcock et al 2021 ).…”

“…A shift from oxidative phosphorylation to glycolysis is a driver of PAEC proliferation and migration early in PH, as glycolysis is needed to meet the metabolic demands of proliferating cells. When PAECs were grown on the aforementioned stiff 50-kilopascal (kPa) matrix representative of tissue stiffness in PAH compared with a soft 1-kPa matrix representative of control lungs by Woodcock et al, miR-7 was downregulated, which led to increased migration (Woodcock et al 2021 ).…”

QKI Promotes Hypoxia Induced Smooth Muscle Reprogramming in Pulmonary Hypertension

“…Studies have shown that QKI is essential for embryonic blood vessel development and visceral endoderm function [19], and is also implicated in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) differentiation [19][20][21]. A recent study implicated that extracellular matrix stiffening increases QKI expression leading to pathogenic pulmonary arterial endothelial function through QKI-miR-7 signaling pathway in PH [22]. However, the biological signi cance of QKI in phenotypic transformation of PASMCs in PH as well as in abnormal pulmonary vascular remodeling remain elusive.…”