Super-Enhancer–Driven LncRNA UNC5B-AS1 Inhibits Inflammatory Phenotypic Transition in Pulmonary Artery Smooth Muscle Cells via Lactylation

BACKGROUND: The phenotypic transition of pulmonary artery smooth muscle cells (PASMCs) is a central pathological alteration in pulmonary artery remodeling, contributing to pulmonary hypertension. Super-enhancers (SEs), characterized by histone modifications and the binding of coactivators, drive the expression of prominent genes that define cellular identity. However, the specific role of SEs, particularly SE-driven lncRNAs (long noncoding RNAs), in hypoxia-induced phenotypic plasticity of PASMCs remains unclear. METHODS: In this study, the lncRNA UNC5B antisense RNA 1 (UNC5B-AS1) regulated by SEs was screened in hypoxic PASMCs using RNA sequencing and H3K27ac (histone 3 lysine 27 acetylation) ChIP (chromatin immunoprecipitation) sequencing. Overexpression or knockdown of UNC5B-AS1 in vitro was performed to elucidate its role in pulmonary hypertension pathogenesis. A serotype 5 adenovirus-associated virus carrying a conserved functional fragment of UNC5B-AS1 was used to treat pulmonary hypertension in vivo. RESULTS: We identified UNC5B-AS1 as an SE-driven lncRNA transcriptionally activated by the transcription factor FOXP3 (forkhead box protein P3), which regulates phenotypic transition in PASMCs. Notably, we demonstrated that UNC5B-AS1 interacts with key glycolytic enzymes in the cytoplasm and likely serves as a molecular scaffold for LRPPRC (leucine-rich PPR motif-containing protein) and oxidative respiratory chain complex IV in mitochondria. Consequently, the deficiency of UNC5B-AS1 in PASMCs promotes the lactylation of promoter regions within inflammatory genes, including those of IL (interleukin)-1β, IL-6, and TNF-α (tumor necrosis factor-α), under hypoxic conditions, ultimately leading to inflammatory phenotypic transition of PASMCs. CONCLUSIONS: Our findings identify SE-driven UNC5B-AS1 as a novel regulatory factor in the hypoxia-induced phenotypic transition of PASMCs and suggest that overexpression of UNC5B-AS1 may represent a promising therapeutic strategy for pulmonary hypertension.