Mmu_circ_0000790 Is Involved in Pulmonary Vascular Remodeling in Mice with HPH via MicroRNA-374c-Mediated FOXC1

Lei Yang,Huan Liang,Xianguo Meng,Li Shen,Zhanjiang Guan,Bingchang Hei,Haitao Yu,Shanshan Qi,Xianchun Wen

doi:10.1016/j.omtn.2019.12.027

Abstract

Recently, the identification of several circular RNAs (circRNAs) as vital regulators of microRNAs (miRNAs) underlines the increasing complexity of non-coding RNA (ncRNA)-mediated regulatory networks. This study aimed to explore the effects of mmu_circ_0000790 on the biological behaviors of pulmonary artery smooth muscle cells (PASMCs) in hypoxic pulmonary hypertension (HPH). The HPH mouse model and hypoxia-induced PASMC model were initially established, and the expression of mmu_circ_0000790 in the pulmonary vascular tissues and hypoxic PASMCs was determined using quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). A series of in vitro experiments such as dual-luciferase, RNA pull-down, and RNA-binding protein immunoprecipitation (RIP) assays were conducted to evaluate the interactions among mmu_circ_0000790, microRNA-374c (miR-374c), and forkhead transcription factor 1 (FOXC1). The potential physiological functions of mmu_circ_0000790, miR-374c, and FOXC1 in hypoxic PASMCs were investigated through gain- and loss-of function approaches. Upregulated mmu_circ_0000790 was found in both the HPH-pulmonary vascular tissues and hypoxic PASMCs. Additionally, mmu_circ_0000790 could competitively bind to miR-374c and consequently upregulate the target gene of miR-374c, FOXC1. It was also observed that mmu_circ_0000790 induced proliferation and inhibited apoptosis of hypoxic PASMCs, which further promoted the pulmonary vascular remodeling in mice with HPH. Therefore, we speculate that mmu_circ_0000790 may serve as a prospective target for the treatment of patients with HPH.

Highlights

Pulmonary arterial hypertension (PAH) is a progressively worsening disorder characterized by an abnormally elevated blood pressure within the pulmonary arteries, accompanied by severe symptoms such as shortness of breath, chest pain, and fainting or syncope.[1,2] Hypoxic pulmonary hypertension (HPH) is recognized as a condition featured with an elevation in pulmonary vascular tone in combination with the structural remodeling of peripheral pulmonary arteries.[3]
Successful establishment of hypoxic pulmonary hypertension (HPH) and hypoxic pulmonary artery smooth muscle cells (PASMCs) models was evaluated by determining the heart weight and the pulmonary vessels of the mice using hematoxylin and eosin (H&E) and immunofluorescence staining
The results of various hemodynamic indexes of mice with HPH showed that Right ventricular systolic pressure (RVSP) and mean pulmonary arterial pressure (mPAP) in the hypoxia group were higher compared to the normoxia group, and the values of these indexes were elevated with an elevation in the continuous feeding days (p < 0.01; Figure 1A)

Summary

Introduction

Pulmonary arterial hypertension (PAH) is a progressively worsening disorder characterized by an abnormally elevated blood pressure within the pulmonary arteries, accompanied by severe symptoms such as shortness of breath, chest pain, and fainting or syncope.[1,2] Hypoxic pulmonary hypertension (HPH) is recognized as a condition featured with an elevation in pulmonary vascular tone in combination with the structural remodeling of peripheral pulmonary arteries.[3]. The patients with HPH show pathological changes such as dysfunction of smooth muscle cells, fibroblasts, as well as pulmonary artery endothelial cells, and the dysfunction is linked to the progressive obliteration of pulmonary arteries.[6] The therapies for PAH include prescriptions of endothelin receptor antagonists, prostaglandins, phosphodiesterase-5 inhibitors, and soluble guanylate cyclase stimulators.[7] Despite the advances made in the currently available therapies for PAH, an important unmet medical need emerges, as PAH presents with high mortality.[8] In recent years, the utilization of circular RNAs (circRNAs) has been reported as important biological molecules for a better understanding of the disease mechanisms and for identification of biomarkers for diagnosis and therapy of disease.[9]

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