Abstract

Background Succinylation, a key post-translational modification, is implicated in the metabolic reprogramming and vascular remodeling of pulmonary arterial hypertension (PAH). While epigenetic regulation, particularly DNA methylation, potentially governs succinylation-related gene expression, its causal links to PAH remain unclear. Methods We performed an integrative causal analysis using two-sample Mendelian randomization (MR) and summary-data-based MR (SMR) to identify succinylation-related genes that influence PAH risk. We leveraged PAH GWAS data (FinnGen) and gene expression quantitative trait loci (eQTLGen). Subsequently, methylation-mediated effect decomposition was applied using DNA methylation data (GoDMC) to explore epigenetic regulation. Experimental validation was conducted in lung tissues from a monocrotaline (MCT)-induced PAH rat model via quantitative reverse transcription polymerase chain reaction (qRT-PCR). Results Genetic analyses identified a significant causal effect of elevated Transgelin 2 ( TAGLN2 ) expression on increased PAH risk. This effect was mediated by two specific DNA methylation sites, cg13892570 and cg16107628, which influenced PAH pathogenesis by regulating TAGLN2 transcription, with mediation proportions of 86.46 and 97.65%, respectively. Sensitivity analyses supported the robustness of these findings. Consistent with the genetic evidence, TAGLN2 mRNA was significantly upregulated in the lungs of MCT-induced PAH rats. Conclusions This study establishes a clear epigenetic causal pathway in which DNA methylation regulates TAGLN2 expression to promote PAH. TAGLN2 is validated as a key disease driver and presents a promising target for diagnostic and therapeutic strategies in PAH.