Yulan Ma

Semaglutide, a glucagon-like peptide-1 receptor agonist, is clinically used as a glucose-lowering and weight loss medication due to its effects on energy metabolism. In heart failure, energy production is impaired due to altered mitochondrial function and increased glycolysis. However, the impact of semaglutide on cardiomyocyte metabolism under pressure overload remains unclear. Here we demonstrate that semaglutide improves cardiac function and reduces hypertrophy and fibrosis in a mouse model of pressure overload-induced heart failure. Semaglutide preserves mitochondrial structure and function under chronic stress. Metabolomics reveals that semaglutide reduces mitochondrial damage, lipid accumulation, and ATP deficiency by promoting pyruvate entry into the tricarboxylic acid cycle and increasing fatty acid oxidation. Transcriptional analysis shows that semaglutide regulates myocardial energy metabolism through the Creb5/NR4a1 axis in the PI3K/AKT pathway, reducing NR4a1 expression and its translocation to mitochondria. NR4a1 knockdown ameliorates mitochondrial dysfunction and abnormal glucose and lipid metabolism in the heart. These findings suggest that semaglutide may be a therapeutic agent for improving cardiac remodeling by modulating energy metabolism.

BACKGROUND AND PURPOSE: Limonin, a naturally occurring tetracyclic triterpenoid, has extensive pharmacological effects. Its role in cardiac hypertrophy remains to be elucidated. We investigated its effects on cardiac hypertrophy along with the potential mechanisms involved. EXPERIMENTAL APPROACH: The effects of limonin on cardiac hypertrophy in C57/BL6 mice caused by aortic banding, plus neonatal rat cardiac myocytes (NRCMs) stimulated with phenylephrine to induce cardiomyocyte hypertrophy in vitro were investigated. KEY RESULTS: Limonin markedly improved the cardiac function and heart weight in aortic banded mice. Limonin-treated mice and NRCMs also produced fewer cardiac hypertrophy markers than those treated with the vehicle in the hypertrophic groups. Sustained aortic banding- or phenylephrine-stimulation impaired cardiac sirtuin 6 (SIRT6) protein levels, which were partially reversed by limonin associated with enhanced activity of PPARα. Sirt6 siRNA inhibited the anti-hypertrophic effects of limonin in vitro. Interestingly, limonin did not influence Sirt6 mRNA levels, but regulated ubiquitin levels. Thus, the protein biosynthesis inhibitor, cycloheximide and proteasome inhibitor, MG-132, were used to determine SIRT6 protein expression levels. Under phenylephrine stimulation, limonin increased SIRT6 protein levels in the presence of cycloheximide, but it did not influence SIRT6 expression in the presence of MG-132, suggesting that limonin promotes SIRT6 levels by inhibiting its ubiquitination degradation. Furthermore, limonin inhibited the degradation of SIRT6 by activating ubiquitin-specific peptidase 10 (USP10), while Usp10 siRNA prevented the beneficial effects of limonin. CONCLUSION AND IMPLICATIONS: Limonin mediates the ubiquitination and degradation of SIRT6 by activating USP10, providing an attractive therapeutic target for cardiac hypertrophy.

An important pathophysiological consequence of pressure overload‐induced cardiac hypertrophy is adverse cardiac remodeling, including structural changes in cardiomyocytes and extracellular matrix. Diosmetin (DIO), a monomethoxyflavone isolated from citrus fruits, had antioxidative stress effects in multiple organs. The purpose of this study was to examine the biological effect of diosmetin on pathological cardiac hypertrophy. In mice, diosmetin treatment reduced cardiac hypertrophy and dysfunction in an aortic banding‐ (AB‐) induced pressure overload model and reducing myocardial oxidative stress by increasing antioxidant gene expression. In vitro, diosmetin (10 or 50 μ m, 12 h or 24 h) protected PE‐induced cardiomyocyte hypertrophy in neonatal rat cardiomyocytes. Mechanistically, diosmetin inhibited autophagy by activating the PI3K/Akt pathway. In particular, diosmetin induced the accumulation of p62 and its interaction with Keap1, promoted the nuclear translocation of Nrf2, and increased the expression of antioxidant stress genes in the process of cardiac hypertrophy. Furthermore, knockdown of p62 in rat primary cardiomyocytes abrogate the protective effect of diosmetin on cardiomyocyte hypertrophy. Similarly, the Nrf2 inhibitor ML385 obviously abolished the above effects by diosmetin treatment. In conclusion, our results suggest that diosmetin protects cardiac hypertrophy under pressure overload through the p62/Keap1/Nrf2 signaling pathway, suggesting the potential of diosmetin as a novel therapy for pathological cardiac hypertrophy.

Background: Dilated cardiomyopathy (DCM) is characterized by enlarged ventricular dimensions and systolic dysfunction and poor prognosis. Myocardial lipid metabolism appears abnormal in DCM. However, the mechanism of lipid metabolism disorders in DCM remains unclear. Methods: A gene set variation analysis (GSVA) were performed to estimate pathway activity related to DCM progression. Three datasets and clinical data downloaded from the Gene Expression Omnibus (GEO), including dilated cardiomyopathy and donor hearts, were integrated to obtain gene expression profiles and identify differentially expressed genes related to lipid metabolism. GO enrichment analyses of differentially expressed lipid metabolism-related genes (DELs) were performed. The clinical information used in this study were obtained from GSE21610 dataset. Data from the EGAS00001003263 were used for external validation and our hospital samples were also tested the expression levels of these genes through RT-PCR. Subsequently, logistic regression model with the LASSO method for DCM prediction was established basing on the 7 DELs. Results: GSVA analysis showed that the fatty acid metabolism was closely related to DCM progression. The integrated dataset identified 19 DELs, including 8 up-regulated and 11 down-regulated genes. A total of 7 DELs were identified by further external validation of the data from the EGAS00001003263 and verified by RT-PCR. By using the LASSO model, 6 genes, including CYP2J2, FGF1, ETNPPL, PLIN2, LPCAT3, and DGKG, were identified to construct a logistic regression model. The area under curve (AUC) values over 0.8 suggested the good performance of the model. Conclusion: Integrated bioinformatic analysis of gene expression in DCM and the effective logistic regression model construct in our study may contribute to the early diagnosis and prevention of DCM in people with high risk of the disease.

INTRODUCTION: Targeted protein degradation represents a promising therapeutic approach, while diabetic cardiomyopathy (DCM) arises as a consequence of aberrant insulin secretion and impaired glucose and lipid metabolism in the heart.. OBJECTIVES: Considering that the Toll-like receptor 9 (TLR9) signaling pathway plays a pivotal role in regulating energy metabolism, safeguarding cardiomyocytes, and influencing glucose uptake, the primary objective of this study was to investigate the impact of TLR9 on diabetic cardiomyopathy (DCM) and elucidate its underlying mechanism. METHODS: Mouse model of DCM was established using intraperitoneal injection of STZ, and mice were transfected with adeno-associated virus serotype 9-TLR9 (AAV9-TLR9) to assess the role of TLR9 in DCM. To explore the mechanism of TLR9 in regulating DCM disease progression, we conducted interactome analysis and employed multiple molecular approaches. RESULTS: Our study revealed a significant correlation between TLR9 expression and mouse DCM. TLR9 overexpression markedly mitigated cardiac dysfunction, myocardial fibrosis, oxidative stress, and apoptosis in DCM, while inflammation levels remained relatively unaffected. Mechanistically, TLR9 overexpression positively modulated mitochondrial bioenergetics and activated the AMPK-PGC1a signaling pathway. Furthermore, we identified Triad3A as an interacting protein that facilitated TLR9's proteasomal degradation through K48-linked ubiquitination. Inhibiting Triad3A expression improved cardiac function and pathological changes in DCM by enhancing TLR9 activity. CONCLUSIONS: The findings of this study highlight the critical role of TLR9 in maintaining cardiac function and mitigating pathological alterations in diabetic cardiomyopathy. Triad3A-mediated regulation of TLR9 expression and function has significant implications for understanding the pathogenesis of DCM. Targeting TLR9 and its interactions with Triad3A may hold promise for the development of novel therapeutic strategies for diabetic cardiomyopathy. Further research is warranted to fully explore the therapeutic potential of TLR9 modulation in the context of cardiovascular diseases.