β-Hydroxybutyrylation Links Ketone Metabolism to Mitochondrial Remodeling in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DbCM) is characterized by metabolic remodeling and energetic stress independent of coronary artery disease. Increased reliance on fatty acid and ketone body metabolism has been observed in DbCM, but the regulatory mechanisms linking altered substrate use to myocardial dysfunction remain poorly understood. In particular, lysine β-hydroxybutyrate (Kbhb), a ketone body-derived, posttranslational modification, has emerged as a potentially critical regulator but has not been fully investigated. We conducted a comprehensive multiomics study integrating metabolomics, transcriptomics, proteomics, and Kbhb-specific proteomics on myocardial tissues in a well-established mouse model of DbCM. Kbhb-modified proteins were systematically mapped and quantified, followed by motif, subcellular localization, and protein-protein interaction analyses. DbCM cardiac tissue exhibited coordinated upregulations of fatty acid β-oxidation, ketone metabolism, and tricarboxylic acid cycle activity at the transcriptomic, proteomic, and metabolomic levels. Kbhb profiling revealed extensive mitochondrial protein modification, with Atp5f1a-K239 identified as a key modification site strongly correlated with β-hydroxybutyrate and isocitric acid concentrations. This study identifies Kbhb as a potential metabolic-epigenetic modifier linking ketone body availability to the regulation of mitochondrial proteins in DbCM. Our findings provide novel insights into metabolic-epigenetic cross talk and identify potential therapeutic targets for interventions to restore mitochondrial function in alleviating diabetic heart disease. ARTICLE HIGHLIGHTS: We performed a multiomics study to better understand dysfunctions in diabetic cardiomyopathy (DbCM) and specifically identify links between lysine β-hydroxybutyrylation (Kbhb), a ketone body-derived, posttranslational modification, and cardiac dysfunction. DbCM cardiac tissue exhibited coordinated upregulations of fatty acid β-oxidation, ketone metabolism, and tricarboxylic acid cycle activity at the transcriptomic, proteomic, and metabolomic levels. Mitochondrial proteins showed that high Kbhb modification and modification of the Atp5f1a-K239 site were strongly correlated with high β-hydroxybutyrate and isocitric acid concentrations. This study identifies Kbhb modification of mitochondrial proteins as a potential mechanism linking ketone body availability to mitochondrial function in DbCM.