Abstract

Dysfunction of vascular endothelial cells is recognized as a critical driver in pulmonary vascular remodeling of pulmonary hypertension (PH). Although interleukin-6 (IL-6) has been firmly established as an indispensable factor leading to pulmonary vascular remodeling, its downstream molecular mechanisms remain incompletely elucidated. Here, we discover that ubiquitin-specific protease 2a (USP2a) is upregulated in lung tissues of PH patients and preclinical PH models, and in IL-6-stimulated endothelial cells. Both the endothelial cell-specific Usp2a genetic deletion and the pharmacological inhibition of USP2a with the inhibitor ML364 alleviate experimental PH manifestations. Mechanistically, USP2a attenuates the degradation of methyltransferase-like 16 (METTL16) by deubiquitination. Notably, METTL16 reciprocally enhances USP2a expression via interactions with eIF3a and eIF3b in a methyltransferase activity-independent manner, establishing a self-reinforcing USP2a-METTL16 regulatory loop. Subsequent investigations reveal that METTL16 enhances N6-methyladenosine (m 6 A)-mediated IL-6 receptor ( IL-6R ) mRNA stabilization, thereby promoting the expression of IL-6R. This study demonstrates that endothelial USP2a-METTL16 loop potentiates IL-6 signaling via IL-6R and represents a promising therapeutic target for PH. The alternative text for this image may have been generated using AI.