HINT2 protects against pressure overload-induced cardiac remodelling through mitochondrial pathways.

Histidine triad nucleotide-binding protein 2 (HINT2) is an enzyme found in mitochondria that functions as a nucleotide hydrolase and transferase. Prior studies have demonstrated that HINT2 plays a crucial role in ischemic heart disease, but its importance in cardiac remodelling remains unknown. Therefore, the current study intends to determine the role of HINT2 in cardiac remodelling. HINT2 expression levels were found to be lower in failing hearts and hypertrophy cardiomyocytes. The mice that overexpressed HINT2 exhibited reduced myocyte hypertrophy and cardiac dysfunction in response to stress. In contrast, the deficiency of HINT2 in the heart of mice resulted in a worsening hypertrophic phenotype. Further analysis indicated that upregulated genes were predominantly associated with the oxidative phosphorylation and mitochondrial complex I pathways in HINT2-overexpressed mice after aortic banding (AB) treatment. This suggests that HINT2 increases the expression of NADH dehydrogenase (ubiquinone) flavoprotein (NDUF) genes. In cellular studies, rotenone was used to disrupt mitochondrial complex I, and the protective effect of HINT2 overexpression was nullified. Lastly, we predicted that thyroid hormone receptor beta might regulate HINT2 transcriptional activity. To conclusion, the current study showcased that HINT2 alleviates pressure overload-induced cardiac remodelling by influencing the activity and assembly of mitochondrial complex I. Thus, targeting HINT2 could be a novel therapeutic strategy for reducing cardiac remodelling.

Macrod1 suppresses diabetic cardiomyopathy via regulating PARP1-NAD+-SIRT3 pathway.

Diabetic cardiomyopathy (DCM), one of the most serious long-term consequences of diabetes, is closely associated with oxidative stress, inflammation and apoptosis in the heart. MACRO domain containing 1 (Macrod1) is an ADP-ribosylhydrolase 1 that is highly enriched in mitochondria, participating in the pathogenesis of cardiovascular diseases. In this study, we investigated the role of Macrod1 in DCM. A mice model was established by feeding a high-fat diet (HFD) and intraperitoneal injection of streptozotocin (STZ). We showed that Macrod1 expression levels were significantly downregulated in cardiac tissue of DCM mice. Reduced expression of Macrod1 was also observed in neonatal rat cardiomyocytes (NRCMs) treated with palmitic acid (PA, 400 µM) in vitro. Knockout of Macrod1 in DCM mice not only worsened glycemic control, but also aggravated cardiac remodeling, mitochondrial dysfunction, NAD+ consumption and oxidative stress, whereas cardiac-specific overexpression of Macrod1 partially reversed these pathological processes. In PA-treated NRCMs, overexpression of Macrod1 significantly inhibited PARP1 expression and restored NAD+ levels, activating SIRT3 to resist oxidative stress. Supplementation with the NAD+ precursor Niacin (50 µM) alleviated oxidative stress in PA-stimulated cardiomyocytes. We revealed that Macrod1 reduced NAD+ consumption by inhibiting PARP1 expression, thereby activating SIRT3 and anti-oxidative stress signaling. This study identifies Macrod1 as a novel target for DCM treatment. Targeting the PARP1-NAD+-SIRT3 axis may open a novel avenue to development of new intervention strategies in DCM. Schematic illustration of macrod1 ameliorating diabetic cardiomyopathy oxidative stress via PARP1-NAD+-SIRT3 axis.

Cardiolipin in myocardial ischaemia-reperfusion injury: From molecular mechanisms to clinical strategies.

Myocardial reperfusion injury occurs when blood flow is restored after ischemia, an essential process to salvage ischemic tissue. However, this phenomenon is intricate, characterized by various harmful effects. Tissue damage in ischemia-reperfusion injury arises from various factors, including the production of reactive oxygen species, the sequestration of proinflammatory immune cells in ischemic tissues, the induction of endoplasmic reticulum stress, and the occurrence of postischemic capillary no-reflow. Secretory phospholipase A2 (sPLA2) plays a crucial role in the eicosanoid pathway by releasing free arachidonic acid from membrane phospholipids' sn-2 position. This liberated arachidonic acid serves as a substrate for various eicosanoid biosynthetic enzymes, including cyclooxygenases, lipoxygenases, and cytochromes P450, ultimately resulting in inflammation and an elevated risk of reperfusion injury. Therefore, the activation of sPLA2 directly correlates with the heightened and accelerated damage observed in myocardial ischemia-reperfusion injury (MIRI). Presently, clinical trials are in progress for medications aimed at sPLA2, presenting promising avenues for intervention. Cardiolipin (CL) plays a crucial role in maintaining mitochondrial function, and its alteration is closely linked to mitochondrial dysfunction observed in MIRI. This paper provides a critical analysis of CL modifications concerning mitochondrial dysfunction in MIRI, along with its associated molecular mechanisms. Additionally, it delves into various pharmacological approaches to prevent or alleviate MIRI, whether by directly targeting mitochondrial CL or through indirect means.

Tectorigenin protects against cardiac fibrosis in diabetic mice heart via activating the adiponectin receptor 1-mediated AMPK pathway.

Diabetic cardiomyopathy (DCM) is a common severe complication of diabetes that occurs independently of hypertension, coronary artery disease, and valvular cardiomyopathy, eventually leading to heart failure. Previous studies have reported that Tectorigenin (TEC) possesses extensive anti-inflammatory and anti-oxidative stress properties. In this present study, the impact of TEC on diabetic cardiomyopathy was examined. The model of DCM in mice was established with the combination of a high-fat diet and STZ treatment. Remarkably, TEC treatment significantly attenuated cardiac fibrosis and improved cardiac dysfunction. Concurrently, TEC was also found to mitigate hyperglycemia and hyperlipidemia in the DCM mouse. At the molecular level, TEC is involved in the activation of AMPK, both in vitro and in vivo, by enhancing its phosphorylation. This is achieved through the regulation of endothelial-mesenchymal transition via the AMPK/TGFß/Smad3 pathway. Furthermore, it was demonstrated that the level of ubiquitination of the adiponectin receptor 1 (AdipoR1) protein is associated with TEC-mediated improvement of cardiac dysfunction in DCM mice. Notably the substantial reduction of myocardial fibrosis. In conclusion, TEC improves cardiac fibrosis in DCM mice by modulating the AdipoR1/AMPK signaling pathway. These findings suggest that TEC could be an effective therapeutic agent for the treatment of diabetic cardiomyopathy.

ADP-ribosylation: An emerging direction for disease treatment.

ADP-ribosylation (ADPr) is a dynamically reversible post-translational modification (PTM) driven primarily by ADP-ribosyltransferases (ADPRTs or ARTs), which have ADP-ribosyl transfer activity. ADPr modification is involved in signaling pathways, DNA damage repair, metabolism, immunity, and inflammation. In recent years, several studies have revealed that new targets or treatments for tumors, cardiovascular diseases, neuromuscular diseases and infectious diseases can be explored by regulating ADPr. Here, we review the recent research progress on ART-mediated ADP-ribosylation and the latest findings in the diagnosis and treatment of related diseases.

Semaglutide ameliorates cardiac remodeling in male mice by optimizing energy substrate utilization through the Creb5/NR4a1 axis.

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.

Isthmin-1 Improves Aging-Related Cardiac Dysfunction in Mice through Enhancing Glycolysis and SIRT1 Deacetylase Activity.

Aging-related cardiac dysfunction poses a major risk factor of mortality for elderly populations, however, efficient treatment for aging-related cardiac dysfunction is far from being known. Isthmin-1 (ISM1) is a novel adipokine that promotes glucose uptake and acts indispensable roles in restraining inflammatory and fibrosis. The present study aims to investigate the potential role and molecular mechanism of ISM1 in aging-related cardiac dysfunction. Aged and matched young mice were overexpressed or silenced with ISM1 to investigate the role of ISM1 in aging-related cardiac dysfunction. Moreover, H9C2 cells were stimulated with D-galactose (D-gal) to examine the role of ISM1 in vitro. Herein, we found that cardiac-specific overexpression of ISM1 significantly mitigated insulin resistance by promoting glucose uptake in aging mice. ISM1 overexpression alleviated while ISM1 silencing deteriorated cellular senescence, cardiac inflammation, and dysfunction in natural and accelerated cardiac aging. Mechanistically, ISM1 promoted glycolysis and activated Sirtuin-1 (SIRT1) through increasing glucose uptake. ISM1 increased glucose uptake via translocating GLUT4 to the surface, thereby enhancing glycolytic flux and hexosamine biosynthetic pathway (HBP) flux, ultimately leading to increased SIRT1 activity through O-GlcNAc modification. ISM1 may serve as a novel potential therapeutic target for preventing aging-related cardiac disease in elderly populations. ISM1 prevents aging-related cardiac dysfunction by promoting glycolysis and enhancing SIRT1 deacetylase activity, making it a promising therapeutic target for aging-related cardiac disease.

Isthmin-1 alleviates cardiac ischaemia/reperfusion injury through cGMP-PKG signalling pathway.

AIMS: Ischaemia/reperfusion (I/R) injury is an important complication of reperfusion therapy for acute myocardial infarction, extremely compromising the cardiac benefits of revascularization; however, specific and efficient treatment for cardiac I/R injury is still lacking. Isthmin-1 (ISM1) is a novel adipokine and plays indispensable roles in regulating glycolipid metabolism and cell survival. The present study aims to investigate the potential role and molecular mechanism of ISM1 in cardiac I/R injury using gain- and loss-of-function approaches. METHODS AND RESULTS: Cardiac-specific ISM1 overexpression and silence were achieved using an adeno-associated virus serotype 9 system, and then these mice were subjected to I/R surgery, followed by biochemical test, echocardiography and histopathologic examinations, etc. Meanwhile, neonatal rat cardiomyocytes (NRCMs) with ISM1 silence or overexpression also received simulated I/R (sI/R) injury to further verify its role in vitro. The potential downstream pathways and molecular targets of ISM1 were screened by RNA sequencing. We also treated injured mice and NRCMs with recombinant ISM1 (rISM1) to explore whether supplementation with ISM1 was sufficient to protect against I/R injury. Furthermore, acute myocardial infarction patients with percutaneous coronary intervention (PCI) and paired healthy controls were included to reveal the clinical relevance of circulating ISM1. Cardiac-specific ISM1 silencing aggravated while ISM1 overexpression alleviated I/R-induced acute cardiac injury and cardiac remodelling and dysfunction. Mechanistically, ISM1 targeted αvß5 integrin to facilitate the nuclear accumulation of nuclear transcription factor Y subunit alpha, transcriptionally increased soluble guanylyl cyclase beta subunit expression, and eventually enhanced cGMP generation. Besides, we confirmed that treatment with rISM1 before or after reperfusion could confer cardioprotective effects in mice. Clinically, lower ISM1 levels post-PCI was associated with worse outcome in patients. CONCLUSION: ISM1 can protect against cardiac I/R injury through cGMP-PKG signalling pathway, and it is a promising therapeutic and predictive target of cardiac I/R injury.

Role of adiponectin in diabetes myocardial ischemia-reperfusion injury and ischemic postconditioning

Abstract Purpose Patients with diabetes are vulnerable to myocardial I/R (ischaemia/reperfusion) injury, but are not responsive to IPO (ischaemic post-conditioning). We hypothesized that decreased cardiac Adiponectin (APN) is responsible for the loss of diabetic heart sensitivity to IPO cardioprotecton. Methods Diabetic rats were subjected to I/R injury (30 min of LAD occlusion followed by 120 min of reperfusion). Myocardial infarct area was determined by TTC staining. Cardiac function was monitored by a microcatheter. ANP, 15-F2t-isoprostane, nitrotyrosine and MDA were measured by assay kits. Levels of p-Akt, total-Akt and GAPDH were determined by Western Blot. Results Diabetic rats subjected to myocardial IR exhibited severe myocardial infarction and oxidative stress injury, lower APN in the plasma and cardiac p-Akt expression ( P <0.05). IPO significantly attenuated myocardial injury and up-regulated plasma APN content and cardiac p-Akt expression in non-diabetic rats but not in diabetic rats. Linear correlation analysis showed that the expression of adiponectin was positively correlated with p-Akt and negatively correlated with myocardial infarction area ( P <0.01). Conclusion Protective effect of IPO was tightly correlated with the expression of adiponectin, exacerbation of I/R injury and ineffectiveness of IPO was partially due to the decline of adiponectin and inactivation of Akt in diabetes mellitus.