Malate-aspartate shuttle inactivation drives pulmonary hypertension through glucose carbon flux rewiring and α-ketoglutarate-dependent epigenetic remodeling.

Pulmonary hypertension (PH) is characterized by progressive pulmonary vascular remodeling, primarily driven by the hyperproliferation of pulmonary artery smooth muscle cells (PASMCs) and their resistance to apoptosis. Metabolic reprogramming, particularly enhanced glycolysis, has been proposed to be involved in PASMCs activation. However, the implicated mechanisms remain incompletely understood. Here, using in-vitro cultured PASMCs and in-vivo PH models, we showed that malate-aspartate shuttle (MAS), a critical system connecting glycolysis to oxidative phosphorylation, was significantly inhibited in PASMCs during PH progression. The contribution of MAS-mediated NADH shuttling to energy supply markedly decreased, while fatty acid oxidation capacity and mitochondrial oxidative phosphorylation were activated as compensatory mechanisms to meet energy demands. Notably, Slc25a11, a key component of the MAS, were significantly decreased by hypoxia, whose silencing lead to evidenced PASMC activation and further recapitulated the major pathological phenotype of PH. Conversely, restoring MAS activity via Slc25a11 overexpression suppressed PASMC hyperproliferation, thereby preventing hypoxia-induced PH progression. Mechanistically, the downregulation of Slc25a11 and subsequent MAS inactivation redirected glucose-derived carbon flux towards the pentose phosphate pathway, generating NADPH to support the antioxidative system and protect PASMCs from oxidative stress. Furthermore, Slc25a11 deficiency hindered the mitochondrial-cytoplasm transfer of α-ketoglutarate (α-KG), resulting in cytoplasmic and nuclear α-KG deficiency. Insufficient nuclear α-KG reduced the activity of the histone demethylase KDM5, increasing H3K4 tri-methylation and activating transcription of proliferation-related genes. Therapeutically, α-KG supplementation restored nuclear α-KG levels, normalized histone demethylation, and ameliorated PASMC hyperproliferation in both in vitro and in vivo PH models. Collectively, this study identified MAS as a critical mediator linking metabolic changes to PASMC phenotype alterations through the modulation of glucose-derived carbon flux and epigenetic modifications. Restoration of MAS activity or α-KG supplementation may provide a potential therapeutic strategy for clinical intervention in patients with PH.