Abstract
BACKGROUND: Circular RNAs (circRNAs) may affect pulmonary artery hypertension (PAH) by regulating the proliferation of pulmonary artery smooth muscle cells (PASMCs), but the specific mechanism has not been fully elucidated. This study aimed to explore the role of hsa_circ_0005372(circ_0005372) in the proliferation of PASMCs. METHODS: Interference lentivirus was used to silence circ_0005372 expression in human PASMCs and to detect changes in cell proliferation by Cell Counting Kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU). RNA antisense purification (RAP) technology was used to screen miRNAs and proteins that may bind to circ_0005372. A double luciferase experiment was used to verify the targeted regulation relationship between circ_0005372/miR-877 and miR-877/adenylate kinase 4 (AK4), and combined with the results of RAP and fluorescence in situ hybridization (FISH) to analyze the mechanism of circ_0005372. RESULTS: Circ_0005372 in PASMCs subjected to hypoxic conditions for 24 h was upregulated, and circ_0005372 was mainly distributed in the cytoplasm. MiR-877-3p was downregulated, and AK4 was upregulated. It was also observed that circ_0005372 and miR-877-3p promoted PASMCs' proliferation. Circ_0005372 could competitively bind to miR-877-3p and consequently upregulate the target gene of miR-877-3p, AK4. Furthermore, the dual luciferase reporter assay verified the binding between circ_0005372 and miR-877-3p, miR-877-3p and AK4. In addition, RAP protein products were analyzed by liquid chromatography mass spectrometry and it was found that circ_0005372 can bind to DNA methyltransferase 1 (DNMT1). CONCLUSIONS: The results showed that circ_0005372 targeted the regulation of miR-877-3p/AK4 axis and may directly bind to DNMT1 to promote the proliferation of PASMCs.