ALKBH5 regulates ACSL4 to sensitize erastin-induced ferroptosis via YTHDF2-dependent mA modification in hypoxic pulmonary hypertension.

Hypoxic pulmonary hypertension (HPH) is a common complication derived from chronic hypoxic lung diseases and is characterized by excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) and obvious pulmonary vascular remodeling (PVR). Despite recent advances, the clinical outcome is still unsatisfactory. Ferroptosis, a newly identified form of programmed cell death, has been reported to participate in cardiovascular disease progression; however, its role in HPH remains undefined. Here, we demonstrate the feasibility of ferroptosis induction and propose an innovative regulatory mechanism by which mA methylation modulates ferroptosis in HPH. We observed that PASMCs exposed to hypoxia were susceptible to erastin-induced ferroptosis. Erastin application increased malondialdehyde (MDA) and reactive oxygen species (ROS) levels, and this effect was abrogated by ferrostatin-1. Moreover, hypoxia notably upregulated acyl-CoA synthetase long-chain family member 4 (ACSL4) expression levels, as well as 5-HETE and MDA levels in both PASMCs and HPH rats. We are the first to identify ACSL4 as having a dual role in HPH, which not only promotes hypoxic PASMC proliferation, but also accounts for lipid peroxidation and sensitivity to erastin-induced ferroptosis. Additionally, mA levels were reduced in hypoxic PASMCs and HPH rat lung tissues, accompanied by a significant increase in AlkB homolog 5 (ALKBH5). Loss of ALKBH5 downregulated ACSL4 mRNA and protein levels, depressed lipid peroxidation and rendered hypoxic PASMCs resistant to erastin-induced ferroptosis. Mechanistically, ALKBH5 permitted ACSL4 mRNA to sustain mA demethylation to evade YTH N6-methyladenosine RNA binding protein 2 (YTHDF2)-mediated mRNA decay through binding to mA-modified sites in the 3'UTR of ACSL4 mRNA. Furthermore, the administration of erastin to HPH rats increased ACSL4 expression, augmented lipid peroxidation, effectively reversed PVR and alleviated pulmonary hypertension. Collectively, our findings suggest that erastin-induced ferroptosis is a promising therapeutic approach for HPH and that intervention with ACSL4 or mA modulators may have a synergistic effect.