ACAA2 lactylation and expression mediate mitochondrial dysfunction in phenylephrine-induced cardiomyocyte hypertrophy.

Background: Pathological cardiac remodeling under chronic stress involves metabolic reprogramming, with lactylation emerging as a critical post-translational regulator of cardiac energetics. Emerging evidence reveals that lactate, beyond serving as an energy substrate, dynamically regulates cellular processes through lactylation-mediated epigenetic modifications. This study investigates ACAA2, a fatty acid β-oxidation enzyme, exploring its lactylation dynamics and metabolic implications in pressure overload-induced cardiomyopathy.

Methods: We performed RNA sequencing on cardiac tissues from mice subjected to transverse aortic constriction (TAC) and sham-operated controls at 4 weeks post-surgery. Differentially expressed lactylation-related genes were identified, with ACAA2 selected for subsequent functional characterization. Neonatal rat ventricular myocytes (NRVMs) were stimulated with phenylephrine (PE) to induce cardiomyocyte hypertrophy. RT-PCR and Western blot analyses were performed to evaluate the expression of the interest gene during cardiac remodeling. Immunoprecipitation was used to confirm the lactylation modification of ACAA2 and detect the changes in this post-translational modification after PE stimulation. RNA interference-mediated silencing of ACAA2 was employed to investigate its functional role in PE-induced hypertrophic responses. Substrate utilization analysis was performed using ELISA-based detection kits, while mitochondrial respiratory function in NRVMs was quantitatively assessed through extracellular flux measurements with the Seahorse XFe24 Analyzer.

Results: Clinical and experimental analyses revealed conserved ACAA2 downregulation in dilated cardiomyopathy patients and TAC mice, showing strong negative correlations with myocardial stress markers and positive association with cardiac function. Knockdown of ACAA2 gene exacerbated PE-induced hypertrophy in NRVMs, accompanied by global lactylation reduction. Silencing of ACAA2 led to increased accumulation of free fatty acids, decreased lactate levels, reduced ATP synthesis, and impaired mitochondrial oxidative respiration, while these changes were partially rescued by sodium lactate treatment.

Conclusions: This study suggests that changes in the expression and lactylation levels of ACAA2 may contribute to the progression of PE induced pathological myocardial hypertrophy, which may be related to mitochondrial oxidative phosphorylation dysfunction. ACAA2 may serve as a potential therapeutic target for the prevention and treatment of heart failure.