Enhancer-Associated LncRNA-ITGA2 Promotes Vascular Remodeling Through ITGA2

BACKGROUND: The proliferation and migration of vascular smooth muscle cells (VSMCs) significantly contribute to vascular remodeling. Recent studies have suggested that enhancer-associated long noncoding RNAs (elncRNAs) play crucial roles in regulating gene expression and cell fate. However, the specific elncRNAs implicated in VSMC dysfunction and their regulatory mechanisms remain poorly understood. METHODS AND RESULTS: This study used multiomics profiling, including CUT&Tag, promoter capture high-throughput chromosome conformation capture, and microarray analysis, to identify long noncoding RNA (LncRNA)-ITGA2 (integrin α2) as a novel elncRNA highly expressed in PDGF (platelet-derived growth factor)–induced proliferative human VSMCs. Notably, LncRNA-ITGA2 was significantly elevated in the coronary atherosclerotic tissues of patients with coronary artery disease compared with those of control subjects. Gain-of-function and loss-of-function studies suggested that LncRNA-ITGA2 markedly enhanced PDGF-induced VSMC proliferation and migration. In vivo, the overexpression of LncRNA-ITGA2 promoted neointimal hyperplasia in a mouse carotid artery injury model, indicating its partial functional conservation. Using RNA sequencing and CRISPR-Cas9 gene editing technology, we identified ITGA2 as a downstream target of LncRNA-ITGA2. Mechanistically, promoter capture high-throughput chromosome conformation capture detected promoter-enhancer interactions at the ITGA2 locus after PDGF-BB (platelet-derived growth factor BB) treatment. Chromatin immunoprecipitation sequencing and chromatin isolation by RNA purification–quantitative polymerase chain reaction demonstrated that LncRNA-ITGA2 directly bound to the enhancer-ITGA2 and increased histone H3 on lysine 27 acetylation in both the enhancer-ITGA2 and the promoter-ITGA2. In addition, chromatin isolation by RNA purification–mass spectrometry and RNA immunoprecipitation revealed that LncRNA-ITGA2 interacted with the DNA-binding protein NONO (nonpou domain containing octamer–binding protein), which also bound to the ITGA2 promoter, as confirmed by chromatin immunoprecipitation–quantitative polymerase chain reaction. Ultimately, the use of knockout cell lines for NONO, LncRNA-ITGA2, and its promoter validated the proposed regulatory mechanism. CONCLUSIONS: This study identifies a novel mechanism by which elncRNA (LncRNA-ITGA2), in a NONO-dependent manner, mediates interactions between Enhancer-ITGA2 and Promoter-ITGA2, resulting in increased ITGA2 expression and subsequently promoting VSMC proliferation and migration. These findings highlight LncRNA-ITGA2 as an attractive diagnostic and therapeutic target for human proliferative vascular diseases.