Identification of sus-PSMB7_0001 as a potential pro-angiogenic circular RNA in neonatal pig hearts

While circular RNAs (circRNAs) regulating angiogenesis have been identified in fish and rodent hearts, their expression profiles in pig hearts remain largely unknown. This study aims to identify circRNAs that regulate angiogenesis in postnatal pig hearts. Total RNA sequencing data on pig heart tissues collected on postnatal days 1 (P1), 3 (P3), 7 (P7) and 28 (P28) were previously reported. This study analyzed conserved circRNAs associated with angiogenesis in the database. Functional studies were conducted in human umbilical vein endothelial cells (HUVECs) and hiPSC-derived endothelial cells (hiPSC-ECs). siRNA-mediated knockdown of circRNAs and miRNAs was performed to validate their functions in regulating angiogenesis. Fluorescence in situ hybridization was used to examine circRNA localization. Sus-PSMB7_0001 expression increased in pig hearts at P7 and P28 compared to P1 and P3. Knockdown of hsa-PSMB7_0025 (the human orthologue of sus-PSMB7_0001) impaired DNA synthesis, mitosis, migration, and tube formation in HUVECs and hiPSC-ECs. hsa-PSMB7_0025 negatively regulated hsa-miR-490-3p. Activation of hsa-miR-490-3p inhibited hiPSC-EC proliferation, while its inhibition promoted proliferation. Inhibition of miR-490-3p upregulated hsa-PSMB7_0025. miR-490-3p regulates five downstream effectors (TP53BP1, TMOD3, CDYL2, FOXO1, and TGFBR1) involved in cell cycle and vascular function. These findings suggest circRNA sus-PSMB7_0001 is a potential pro-angiogenic molecule in neonatal pig hearts.