mmu_circ_0000790 Is Involved in Pulmonary Vascular Remodeling in Mice with HPH via MicroRNA-374c-Mediated FOXC1

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.