Fibulin 1, targeted by microRNA-24-3p, promotes cell proliferation and migration in vascular smooth muscle cells, contributing to the development of atherosclerosis in APOE-/- mice.

Extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) are the main components of atherosclerosis (AS) plaque. VSMCs participate in plaque formation through phenotypic transformation. The complex interplay between ECM and VSMCs plays vital roles in the progression of AS throughout the disease. An in-depth investigation into the functions of ECM-related molecules in VSMC development might contribute to deciphering the complexity of AS pathogenesis. In this study, the roles and molecular mechanisms of the ECM-related molecule Fibulin-1 (FBLN1) in the development of AS and VSMCs were explored using RNA sequencing, bioinformatics analysis, and cell experiments. Furthermore, the expression of FBLN1, as determined by western blot analysis, immunohistochemistry, and real-time quantitative PCR, was significantly increased in AS vascular samples compared to normal vascular samples. Silencing the FBLN1 through AAV viral injection in mice revealed an improvement in AS. Functional analyses revealed that FBLN1 promoted VSMC proliferation, migration, and wound healing. Combined with RNA sequencing and TargetScan7.2 prediction data, 22 microRNAs (miRNAs) were found to have the potential for direct interaction with the FBLN1 3'UTR in VSMCs. Among these 22 miRNAs, it was demonstrated that microRNA-24-3p (miR-24-3p) could negatively regulate FBLN1 expression by directly binding to the FBLN1 3'UTR. Moreover, miR-24-3p inhibited cell proliferation, migration, and wound healing, and suppressed the expression of Ki67, matrix metalloproteinase-2 and -9 (MMP2/9) by targeting FBLN1 in VSMCs. Meanwhile, inhibition of FBLN1 expression could restrain VSMC phenotypic transformation. In conclusion, miR-24-3p inhibited VSMC proliferation and migration by targeting FBLN1. Additionally, multiple miRNAs with the potential to interact with the FBLN1 3'UTR were identified. These findings might deepen our understanding of ECM gene regulatory networks and the complex etiology of AS.