Burgoyne, J. R. | Search bioRxiv

bioRxiv2025

Dietary glutamine supplementation alleviates age-related cardiac dysfunction by reducing elevated H3K27me3

BackgroundChanges to the epigenetic landscape play an important role in cardiovascular aging, where alterations in histone modifications influence gene expression by regulating DNA accessibility and chromatin structure. Our investigation into epigenetic changes during myocardial aging revealed that the repressive epigenetic mark H3K27me3 is significantly upregulated in aged mice and humans. This increase in H3K27me3 was shown to impair cardiomyocyte autophagy and drive metabolic reprogramming, key features of myocardial aging and causatively linked to dysfunction. Notably, by alleviating this repressive mark through a modified diet, we successfully mitigated the aged myocardial phenotype. MethodsHeart tissue from young and aged mice and humans was analyzed for H3K27me3 levels using immunoblotting and immunofluorescence staining. Genes regulated by H3K27me3 were identified through CUT&RUN-Seq and RNA-Seq, while metabolites were profiled using metabolomics. In neonatal rat ventricular myocytes (NRVMs), H3K27me3 levels were elevated by siRNA-mediated knockdown of UTX. Cellular metabolism was investigated using a Seahorse analyzer in cardiomyocytes with basal or elevated H3K27me3 levels. In further human studies, we assessed how circulating glutamine levels associate with the incidence of heart failure and the association of genetic variants within the SLC1A5 region with heart disease. In aged mice, H3K27me3 levels were reduced through a modified diet, and heart function was evaluated using echocardiography. Subsequently, hearts were processed for biochemical analysis, and autophagy was assessed using electron microscopy. ResultsH3K27me3 was significantly elevated in the aged mouse and human myocardium. This observed elevation in H3K27me3 was found to be attributed to impaired glutamine metabolism, resulting from reduced expression of the glutamine transporter SLC1A5 in the aged myocardium. Furthermore, elevation in H3K27me3 was found to contribute to impaired cardiomyocyte autophagy and metabolic dysfunction. In aged mice supplemented with a high glutamine diet this attenuated myocardial H3K27me3 and improved cardiac function. Furthermore, a high-glutamine diet reversed H3K27me3-mediated impairment in cardiac autophagy in aged mice. ConclusionsReduction in SLC1A5 during aging is likely to lead to increased myocardial H3K27me3 that results in impaired autophagy and metabolic reprogramming that contribute to the aged cardiac phenotype. Our findings also suggest glutamine may improve cardiac health in the aged population by lowering H3K27me3. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIElevation in H3K27me3 during aging is likely to lead to impaired myocardial autophagy and metabolic reprogramming. C_LIO_LIReduction in SLC1A5 during aging in humans is likely to contribute to myocardial dysfunction C_LIO_LIDietary supplementation of glutamine improves cardiac function in aged mice. C_LI What are the clinical implications?O_LITargeting H3K27me3 in the aged population may to mitigate cardiovascular disease C_LIO_LIDietary glutamine supplementation offers a promising strategy to improve cardiac function during aging. C_LI

cell biology↗

bioRxiv2025

Targeting C42 in PKGIα alleviates diastolic dysfunction in HFpEF

BackgroundIn our exploration of novel therapeutic strategies for treating heart failure with preserved ejection fraction (HFpEF), we focused on cysteine 42 (C42) in cGMP-dependent protein kinase I (PKGI), which plays a crucial role in regulating blood pressure and diastolic relaxation. Our findings demonstrate that targeting C42 on PKGI with urolithin A effectively limits diastolic dysfunction and cardiac remodeling in a multi-hit mouse model of HFpEF, while also improving the kinetics of relaxation and contraction in human-engineered heart tissue. MethodsWe evaluated various polyphenols, including urolithin A, for their capacity to oxidize and activate PKGI. This assessment involved recombinant protein, isolated rat aortic smooth muscle cells, and myography experiments using isolated mesenteric vessels. Additionally, we investigated the ability of urolithin A to stimulate PKGI-dependent phosphorylation of phospholamban (PLN) in neonatal rat ventricular myocytes (NRVMs). A multi-hit mouse model was employed to induce HFpEF in wild-type and C42S PKGI knock-in (KI) mice. Following this, the mice were given vehicle or urolithin A by gavage, and heart function was evaluated using echocardiography. The relevance to human physiology was assessed using human-engineered heart tissue. ResultsThe polyphenols quercetin, fisetin, and urolithin A were shown to induce C42-dependent activation of PKGI. This mechanism of kinase activation led to vasorelaxation, which was attenuated in mesenteric vessels isolated from KI mice. Additionally, urolithin A treatment promoted PKGI-dependent phosphorylation of phospholamban in isolated cardiomyocytes. In a multi-hit model of HFpEF, urolithin A reversed diastolic dysfunction and cardiac remodeling in wild-type mice, but not in KI mice. These findings were shown to be likely relevant to humans, as urolithin A also enhanced the kinetics of relaxation and contraction in human-engineered heart tissue. ConclusionsTargeting C42 in PKGI with urolithin A presents a promising new strategy for the treatment of HFpEF.

biochemistry↗