Abstract
Circadian time of intake gates the cardioprotective effects of glucocorticoid administration in both healthy and infarcted hearts. The cardiomyocyte-specific glucocorticoid receptor (GR) and its cofactor, Krüppel-like factor 15 (KLF15), play critical roles in maintaining normal heart function in the long term and serve as pleiotropic regulators of cardiac metabolism. Despite this understanding, the cardiomyocyte-autonomous metabolic targets influenced by the concerted epigenetic action of the GR/KLF15 axis remain undefined. Here, we demonstrated the critical roles of the cardiomyocyte-specific GR and KLF15 in orchestrating a circadian-dependent glucose oxidation program within the heart. Combining integrated transcriptomics and epigenomics with cardiomyocyte-specific inducible ablation of GR or KLF15, we identified their synergistic role in the activation of adiponectin receptor expression (Adipor1) and the mitochondrial pyruvate complex (Mpc1/2), thereby enhancing insulin-stimulated glucose uptake and pyruvate oxidation. Furthermore, in obese diabetic (db/db) mice exhibiting insulin resistance and impaired glucose oxidation, light-phase prednisone administration, as opposed to dark-phase prednisone dosing, restored cardiomyocyte glucose oxidation and improved diastolic function. These effects were blocked by combined in vivo knockdown of GR and KLF15 levels in db/db hearts. In summary, this study leveraged the circadian-dependent cardioprotective effects of glucocorticoids to identify cardiomyocyte-autonomous targets for the GR/KLF15 axis in glucose metabolism.
Authors
Hima Bindu Durumutla, Ashok Daniel Prabakaran, Fadoua El Abdellaoui Soussi, Olukunle Akinborewa, Hannah Latimer, Kevin McFarland, Kevin Piczer, Cole Werbrich, Mukesh K. Jain, Saptarsi M. Haldar, Mattia Quattrocelli
Figure 3
Cardiomyocyte GR and KLF15 are required for the ZT0 prednisone effects on gene transactivation, insulin sensitization, and pyruvate oxidation in heart.
