Enhanced Mitochondrial Mrs2-Mg 2+ Signaling Drives Mitochondrial Dysfunction in Pulmonary Arterial Hypertension Rats

BACKGROUND: Pulmonary arterial hypertension (PAH) involves ionic homeostasis and vascular remodeling. While cytosolic magnesium ([Mg 2+ ]ᵢ) depletion is a hallmark of PAH, the role of mitochondrial Mg 2+ ( m Mg 2+ ) remains elusive. mitochondrial RNA splicing 2 (Mrs2), the primary m Mg 2+ influx transporter, is hypothesized to drive PAH by orchestrating mitochondrial ionic imbalance and dysfunction. METHODS: Primary pulmonary arterial smooth muscle cells isolated from monocrotaline-induced PAH rats were used for mechanistic investigation, with key metabolic and mitochondrial alterations validated in the Su5416 (semaxanib)/hypoxia model. In vivo, adeno-associated virus-mediated Mrs2 knockdown was used to evaluate therapeutic potential. RESULTS: In PAH-pulmonary arterial smooth muscle cells, Mrs2 upregulation and Slc41a3 (solute carrier family 41 member 3) downregulation caused m Mg 2+ overload and [Mg 2+ ]ᵢ depletion. Excess m Mg 2+ promoted pyruvate dehydrogenase phosphorylation, driving glycolysis and lactate production in association with Hif-1α (hypoxia-inducible factor-1α) activation and a Pkm2 (pyruvate kinase M2)-linked glycolytic shift. Proinflammatory cytokines further amplified lactate accumulation, which exacerbated m Mg 2+ and cytosolic calcium ([Ca 2+ ]ᵢ) overload, establishing a maladaptive m Mg 2+ -lactate feedback loop. This ionic-metabolic stress triggered Ca 2+ -dependent mitochondrial fission, redox imbalance, and pulmonary arterial smooth muscle cell hyperproliferation. Moreover, Mrs2 was associated with enhanced Trpc3 (transient receptor potential channel 3)-dependent mitochondrial Ca 2+ uptake. Crucially, Mrs2 knockdown restored mitochondrial bioenergetics and morphology, attenuated vascular remodeling, and improved hemodynamics in monocrotaline-PAH rats. CONCLUSIONS: Aberrant Mrs2-mediated m Mg 2+ signaling disrupts global ionic and metabolic homeostasis, driving mitochondrial dysfunction and pathogenic remodeling in PAH. Targeting the Mrs2-centered ionic-metabolic-dynamic axis may represent a potential therapeutic approach that warrants further investigation to interrupt PAH progression.