SOX17 Regulates Nestin/p16^INK4a Axis to Mitigate Endothelial Senescence in Pulmonary Arterial Hypertension

Emerging evidence indicates that endothelial cell senescence plays a critical role in the pathogenesis of pulmonary arterial hypertension (PAH). However, the underlying mechanisms and signaling pathways driving pulmonary endothelial senescence in PAH remain incompletely understood. In this study, we used a novel functional genomics approach to show that the intermediate filament protein Nestin binds to a cis-regulatory element (cis-RE) on the cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) locus, repressing p16^INK4a expression and mitigating cellular senescence in human pulmonary arterial endothelial cells (PAECs). Consistently, Nestin expression was markedly downregulated in both PAH patients and rodent models, leading to increased p16^INK4a level and enhanced endothelial senescence in PAH-affected lungs. We further demonstrated that SRY-related HMG-box 17 (SOX17), a transcription factor known to be associated with PAH, activated Nestin expression by binding directly to the Nestin promoter, which inhibited cellular senescence by suppressing p16^INK4a expression in PAECs. In vivo, SOX17 overexpression, which leads to upregulation of Nestin and downregulation of p16^INK4a in lungs of PAH rat models, significantly reduced PAEC senescence, attenuated pulmonary vascular remodeling, and alleviated PAH severity. Conversely, silencing of Nestin in the SOX17 overexpressing PAECs exacerbated PAEC senescence and worsened PAH in rodents. Our findings reveal a novel SOX17-Nestin-p16^INK4a regulatory pathway that governs pulmonary endothelial cell senescence, which offers new insights into PAH pathobiology and represents a promising therapeutic target for intervention.