Hypoxic acclimation improves cardiac redox homeostasis and protects heart against ischemia-reperfusion injury through upregulation of O-GlcNAcylation

CARD9 protein SUMOylation regulates HOXB5 nuclear translocation and Parkin-mediated mitophagy in myocardial I/R injury

Myocardial injury induced by ischemia-reperfusion (I/R) remains a difficult clinical problem. However, the exact mechanisms underlying I/R-induced have yet to be clarified. CARD9 is an important cytoplasmic-binding protein. In this study, an immunocoprecipitation assay showed that SUMOylation of the CARD9 protein promoted the binding of CARD9 to HOXB5, but hindered the O-GlcNAc glycosylation of HOXB5, a predicted transcription factor of Parkin and a key factor in mitophagy. O-GlcNAc glycosylation is an important signal for translocation of proteins from the cytoplasm to the nucleus. CARD9 protein SUMOylation is regulated by PIAS3, which is related to I/R-induced myocardial injury. Therefore, we propose that knockdown of PIAS3 inhibits SUMOylation of the CARD9 protein, facilitates the dissociation of CARD9 and HOXB5, which increases the O-GlcNAc-mediated glycosylation of HOXB5, while the resulting HOXB5 nuclear translocation promotes Parkin-induced mitophagy and alleviates myocardial I/R injury.

Advances in macrophage metabolic reprogramming in myocardial ischemia-reperfusion

Acute myocardial infarction (AMI) is the leading cause of death worldwide, and reperfusion therapy is a critical therapeutic approach to reduce myocardial ischemic injury and minimize infarct size. However, ischemia/reperfusion (I/R) itself also causes myocardial injury, and inflammation is an essential mechanism by which it leads to myocardial injury, with macrophages as crucial immune cells in this process. Macrophages are innate immune cells that maintain tissue homeostasis, host defence during pathogen infection, and repair during tissue injury. During the acute phase of I/R, M1-type macrophages generate a pro-inflammatory milieu, clear necrotic myocardial tissue, and further recruit mononuclear (CCR2+) macrophages. Over time, the reparative (M2 type) macrophages gradually became dominant. In recent years, metabolic studies have shown a clear correlation between the metabolic profile of macrophages and their phenotype and function. M1-type macrophages are mainly characterized by glycolytic energy supply, and their tricarboxylic acid (TCA) cycle and mitochondrial oxidative phosphorylation (OXPHOS) processes are impaired. In contrast, M2 macrophages rely primarily on OXPHOS for energy. Changing the metabolic profile of macrophages can alter the macrophage phenotype. Altered energy pathways are also present in macrophages during I/R, and intervention in this process contributes to earlier and greater M2 macrophage infiltration, which may be a potential target for the treatment of myocardial I/R injury. Therefore, this paper mainly reviews the characteristics of macrophage energy metabolism alteration and phenotypic transition during I/R and its mechanism of mediating myocardial injury to provide a basis for further research in this field.

Post-translational modifications of pyruvate dehydrogenase complex in cardiovascular disease

Pyruvate dehydrogenase complex (PDC) is a crucial enzyme that connects glycolysis and the tricarboxylic acid (TCA) cycle pathway. It plays an essential role in regulating glucose metabolism for energy production by catalyzing the oxidative decarboxylation of pyruvate to acetyl coenzyme A. Importantly, the activity of PDC is regulated through post-translational modifications (PTMs), phosphorylation, acetylation, and O-GlcNAcylation. These PTMs have significant effects on PDC activity under both physiological and pathophysiological conditions, making them potential targets for metabolism-related diseases. This review specifically focuses on the PTMs of PDC in cardiovascular diseases (CVDs) such as myocardial ischemia/reperfusion injury, diabetic cardiomyopathy, obesity-related cardiomyopathy, heart failure (HF), and vascular diseases. The findings from this review offer theoretical references for the diagnosis, treatment, and prognosis of CVD.

Astrocytic LRP1 enables mitochondria transfer to neurons and mitigates brain ischemic stroke by suppressing ARF1 lactylation

Low-density lipoprotein receptor-related protein-1 (LRP1) is an endocytic/signaling cell-surface receptor that regulates diverse cellular functions, including cell survival, differentiation, and proliferation. LRP1 has been previously implicated in the pathogenesis of neurodegenerative disorders, but there are inconsistencies in its functions. Therefore, whether and how LRP1 maintains brain homeostasis remains to be clarified. Here, we report that astrocytic LRP1 promotes astrocyte-to-neuron mitochondria transfer by reducing lactate production and ADP-ribosylation factor 1 (ARF1) lactylation. In astrocytes, LRP1 suppressed glucose uptake, glycolysis, and lactate production, leading to reduced lactylation of ARF1. Suppression of astrocytic LRP1 reduced mitochondria transfer into damaged neurons and worsened ischemia-reperfusion injury in a mouse model of ischemic stroke. Furthermore, we examined lactate levels in human patients with stroke. Cerebrospinal fluid (CSF) lactate was elevated in stroke patients and inversely correlated with astrocytic mitochondria. These findings reveal a protective role of LRP1 in brain ischemic stroke by enabling mitochondria-mediated astrocyte-neuron crosstalk.

Metagenomic analysis demonstrates distinct changes in the gut microbiome of Kawasaki diseases children

Background

Kawasaki disease (KD) has been considered as the most common required pediatric cardiovascular diseases among the world. However, the molecular mechanisms of KD were not fully underlined, leading to a confused situation in disease management and providing precious prognosis prediction. The disorders of gut microbiome had been identified among several cardiovascular diseases and inflammation conditions. Therefore, it is urgent to elucidate the characteristics of gut microbiome in KD and demonstrate its potential role in regulating intravenous immunoglobulin (IVIG) resistance and coronary artery injuries.

Methods

A total of 96 KD children and 62 controls were enrolled in the study. One hundred forty fecal samples had been harvested from KD patients, including individuals before or after IVIG treatment, with or without early coronary artery lesions and IVIG resistance. Fecal samples had been collected before and after IVIG administration and stored at -80°C. Then, metagenomic analysis had been done using Illumina NovaSeq 6000 platform. After that, the different strains and functional differences among comparisons were identified.

Results

First, significant changes had been observed between KD and their controls. We found that the decrease of Akkermansia muciniphila, Faecalibacterium prausnitzii, Bacteroides uniformis, and Bacteroides ovatus and the increase of pathogenic bacteria Finegoldia magna, Abiotrophia defectiva, and Anaerococcus prevotii perhaps closely related to the incidence of KD. Then, metagenomic and responding functional analysis demonstrated that short-chain fatty acid pathways and related strains were associated with different outcomes of therapeutic efficacies. Among them, the reduction of Bacteroides thetaiotaomicron, the enrichment of Enterococcus faecalis and antibiotic resistance genes had been found to be involved in IVIG resistance of KD. Moreover, our data also revealed several potential pathogenetic microbiome of that KD patients with coronary artery lesions.

Conclusion

These results strongly proved that distinct changes in the gut microbiome of KD and the dysfunction of gut microbiomes should be responsible for the pathogenesis of KD and significantly impact the prognosis of KD.

Role of O-linked N-acetylglucosamine protein modification in oxidative stress-induced autophagy: a novel target for bone remodeling

O-linked N-acetylglucosamine protein modification (O-GlcNAcylation) is a dynamic post-translational modification (PTM) involving the covalent binding of serine and/or threonine residues, which regulates bone cell homeostasis. Reactive oxygen species (ROS) are increased due to oxidative stress in various pathological contexts related to bone remodeling, such as osteoporosis, arthritis, and bone fracture. Autophagy serves as a scavenger for ROS within bone marrow-derived mesenchymal stem cells, osteoclasts, and osteoblasts. However, oxidative stress-induced autophagy is affected by the metabolic status, leading to unfavorable clinical outcomes. O-GlcNAcylation can regulate the autophagy process both directly and indirectly through oxidative stress-related signaling pathways, ultimately improving bone remodeling. The present interventions for the bone remodeling process often focus on promoting osteogenesis or inhibiting osteoclast absorption, ignoring the effect of PTM on the overall process of bone remodeling. This review explores how O-GlcNAcylation synergizes with autophagy to exert multiple regulatory effects on bone remodeling under oxidative stress stimulation, indicating the application of O-GlcNAcylation as a new molecular target in the field of bone remodeling.

Mild therapeutic hypothermia upregulates the O-GlcNAcylation level of COX10 to alleviate mitochondrial damage induced by myocardial ischemia-reperfusion injury

OBJECTIVE

Mild therapeutic hypothermia (MTH) is an important method for perioperative prevention and treatment of myocardial ischemia-reperfusion injury (MIRI). Modifying mitochondrial proteins after protein translation to regulate mitochondrial function is one of the mechanisms for improving myocardial ischemia-reperfusion injury. This study investigated the relationship between shallow hypothermia treatment improving myocardial ischemia-reperfusion injury and the O-GlcNAcylation level of COX10.

METHODS

We used in vivo Langendorff model and in vitro hypoxia/reoxygenation (H/R) cell model to investigate the effects of MTH on myocardial ischemia-reperfusion injury. Histological changes, myocardial enzymes, oxidative stress, and mitochondrial structure/function were assessed. Mechanistic studies involved various molecular biology methods such as ELISA, immunoprecipitation (IP), WB, and immunofluorescence.

RESULTS

Our research results indicate that MTH upregulates the O-GlcNACylation level of COX10, improves mitochondrial function, and inhibits the expression of ROS to improve myocardial ischemia-reperfusion injury. In vivo, MTH effectively alleviates ischemia-reperfusion induced cardiac dysfunction, myocardial injury, mitochondrial damage, and redox imbalance. In vitro, the OGT inhibitor ALX inhibits the OGT mediated O-GlcNA acylation signaling pathway, downregulates the O-Glc acylation level of COX10, promotes ROS release, and counteracts the protective effect of MTH. On the contrary, the OGA inhibitor ThG showed opposite effects to ALX, further confirming that MTH activated the OGT mediated O-GlcNAcylation signaling pathway to exert cardioprotective effects.

CONCLUSIONS

In summary, MTH activates OGT mediated O-glycosylation modified COX10 to regulate mitochondrial function and improve myocardial ischemia-reperfusion injury, which provides important theoretical basis for the clinical application of MTH.

O-GlcNAcylation in ischemic diseases

Protein glycosylation is an extensively studied field, with the most studied forms being oxygen or nitrogen-linked N-acetylglucosamine (O-GlcNAc or N-GlcNAc) glycosylation. Particular residues on proteins are targeted by O-GlcNAcylation, which is among the most intricate post-translational modifications. Significantly contributing to an organism's proteome, it influences numerous factors affecting protein stability, function, and subcellular localization. It also modifies the cellular function of target proteins that have crucial responsibilities in controlling pathways related to the central nervous system, cardiovascular homeostasis, and other organ functions. Under conditions of acute stress, changes in the levels of O-GlcNAcylation of these proteins may have a defensive function. Nevertheless, deviant O-GlcNAcylation nullifies this safeguard and stimulates the advancement of several ailments, the prognosis of which relies on the cellular milieu. Hence, this review provides a concise overview of the function and comprehension of O-GlcNAcylation in ischemia diseases, aiming to facilitate the discovery of new therapeutic targets for efficient treatment, particularly in patients with diabetes.

Roles of O-GlcNAcylation in Mitochondrial Homeostasis and Cardiovascular Diseases

Protein posttranslational modifications are important factors that mediate the fine regulation of signaling molecules. O-linked β-N-acetylglucosamine-modification (O-GlcNAcylation) is a monosaccharide modification on N-acetylglucosamine linked to the hydroxyl terminus of serine and threonine of proteins. O-GlcNAcylation is responsive to cellular stress as a reversible and posttranslational modification of nuclear, mitochondrial and cytoplasmic proteins. Mitochondrial proteins are the main targets of O-GlcNAcylation and O-GlcNAcylation is a key regulator of mitochondrial homeostasis by directly regulating the mitochondrial proteome or protein activity and function. Disruption of O-GlcNAcylation is closely related to mitochondrial dysfunction. More importantly, the O-GlcNAcylation of cardiac proteins has been proven to be protective or harmful to cardiac function. Mitochondrial homeostasis is crucial for cardiac contractile function and myocardial cell metabolism, and the imbalance of mitochondrial homeostasis plays a crucial role in the pathogenesis of cardiovascular diseases (CVDs). In this review, we will focus on the interactions between protein O-GlcNAcylation and mitochondrial homeostasis and provide insights on the role of mitochondrial protein O-GlcNAcylation in CVDs.

PI3K/AKT pathway modulation and cold acclimation alleviation concerning apoptosis and necroptosis in broiler thymus

Moderate cold stimulation regulates the thymus's growth and function and facilitates cold acclimatization in broilers. However, the underlying mechanism remains unknown. To explore the possible mechanism of the thymus in cold-acclimated broilers against cold stress, 240 one-day-old Arbor Acres (AA) broilers were assigned to 2 groups randomly. The control group (C) was housed at conventional temperatures. The temperature during the first week was 33°C to 34°C. Between the ages of 8 and 32 d, the temperature was lowered by 1°C every 2 d, i.e., gradually from 32°C to 20°C, and then maintained at 20°C until 42 d of age. The cold-acclimated group (C-3) was housed at the same temperature as C from 1 to 7 d after birth. Between 8 and 42 d, the temperature of C-3 was 3°C colder than C. After 24 h exposure to acute cold stress (ACS) at 42 d, C and C-3 were named as S and S-3. The results showed that ACS was able to induce oxidation stress, modulate PI3K/AKT signal, and cause necroptosis and apoptosis in broiler thymus. By contrast, cold acclimation could alleviate apoptosis and necroptosis induced by cold stress via alleviating oxidative stress, efficiently activating the PI3K/AKT signal, as well as decreasing apoptotic and necrotic genes' levels. This study offers a novel theoretical basis for cold acclimation to improve the body's cold tolerance.

Mitochondrial energy metabolism in diabetic cardiomyopathy: Physiological adaption, pathogenesis, and therapeutic targets

ABSTRACT

Diabetic cardiomyopathy is defined as abnormal structure and function of the heart in the setting of diabetes, which could eventually develop heart failure and leads to the death of the patients. Although blood glucose control and medications to heart failure show beneficial effects on this disease, there is currently no specific treatment for diabetic cardiomyopathy. Over the past few decades, the pathophysiology of diabetic cardiomyopathy has been extensively studied, and an increasing number of studies pinpoint that impaired mitochondrial energy metabolism is a key mediator as well as a therapeutic target. In this review, we summarize the latest research in the field of diabetic cardiomyopathy, focusing on mitochondrial damage and adaptation, altered energy substrates, and potential therapeutic targets. A better understanding of the mitochondrial energy metabolism in diabetic cardiomyopathy may help to gain more mechanistic insights and generate more precise mitochondria-oriented therapies to treat this disease.

O-GlcNAcylation: a pro-survival response to acute stress in the cardiovascular and central nervous systems

O-GlcNAcylation is a unique monosaccharide modification that is ubiquitously present in numerous nucleoplasmic and mitochondrial proteins. The hexosamine biosynthesis pathway (HBP), which is a key branch of glycolysis, provides the unique sugar donor UDP-GlcNAc for the O-GlcNAc modification. Thus, HBP/O-GlcNAcylation can act as a nutrient sensor to perceive changes in nutrient levels and trigger O-GlcNAc modifications of functional proteins in cellular (patho-)physiology, thereby regulating diverse metabolic processes. An imbalance in O-GlcNAcylation has been shown to be a pathogenic contributor to dysfunction in metabolic diseases, including type 2 diabetes, cancer, and neurodegeneration. However, under acute stress conditions, protein O-GlcNAc modification exhibits rapid and transient upregulation, which is strongly correlated with stress tolerance and cell survival. In this context, we discuss the metabolic, pharmacological and genetic modulation of HBP/O-GlcNAc modification in the biological system, the beneficial role of O-GlcNAcylation in regulating stress tolerance for cardioprotection, and neuroprotection, which is a novel and rapidly growing field. Current evidence suggests that transient activation of the O-GlcNAc modification represents a potent pro-survival signalling pathway and may provide a promising strategy for stress-related disorder therapy.

Biochemical implications of robotic surgery: a new frontier in the operating room

Robotic surgery represents a milestone in surgical procedures, offering advantages such as less invasive methods, elimination of tremors, scaled motion, and 3D visualization. This in-depth analysis explores the complex biochemical effects of robotic methods. The use of pneumoperitoneum and steep Trendelenburg positioning can decrease pulmonary compliance and splanchnic perfusion while increasing hypercarbia. However, robotic surgery reduces surgical stress and inflammation by minimizing tissue trauma. This contributes to faster recovery but may limit immune function. Robotic procedures also limit ischemia-reperfusion injury and oxidative damage compared to open surgery. They also help preserve native antioxidant defenses and coagulation. In a clinical setting, robotic procedures reduce blood loss, pain, complications, and length of stay compared to traditional procedures. However, risks remain, including device failure, the need for conversion to open surgery and increased costs. On the oncology side, there is still debate about margins, recurrence, and long-term survival. The advent of advanced technologies, such as intraoperative biosensors, localized drug delivery systems, and the incorporation of artificial intelligence, may further improve the efficiency of robotic surgery. However, ethical dilemmas regarding patient consent, privacy, access, and regulation of this disruptive innovation need to be addressed. Overall, this review sheds light on the complex biochemical implications of robotic surgery and highlights areas that require additional mechanistic investigation. It presents a comprehensive approach to responsibly maximize the potential of robotic surgery to improve patient outcomes, integrating technical skill with careful consideration of physiological and ethical issues.

Glycyrrhizin attenuates myocardial ischemia reperfusion injury by suppressing Inflammation, oxidative stress, and ferroptosis via the HMGB1-TLR4-GPX4 pathway

Ferroptosis, a form of regulated cell death process, play an important role in myocardial ischemia‒reperfusion (I/R) injury. Glycyrrhizin (GL), a natural glycoconjugate triterpene, has the property to improve growth rate, immune regulation, antioxidant, anti-inflammatory. However, whether GL can attenuate myocardial I/R injury by modulating ferroptosis or other mechanisms are still unclear. In this study, SD rats underwent in vivo myocardial ischemia/reperfusion (I/R) surgery, while H9C2 cells were subjected to the hypoxia/reoxygenation (H/R) model for in vitro experiments. In addition, TAK-242, a TLR4-specific antagonist, and GL were also used to evaluate the effect and mechanisms of GL on the cardiac function and expression of ferroptosis-related gene and protein in vivo and vitro. The results show that GL decreased not only the expression of the inflammation-related factors (HMGB1, TNF-α, IL-6, IL-18 and IL-1β), but also reduced the number of TUNEL-positive cardiomyocytes, and mitigated pathological alterations in I/R injury. In addition, GL decreased the levels of MDA, promoted antioxidant capacity such as GSH, CAT, Cu/Zn-SOD, Mn-SOD, and SOD in vivo and vitro. More importantly, GL and TAK-242 regulate ferroptosis-related protein and gene expression in I/R and H/R model. Surprisingly, GL may ameliorate cardiomyocyte ferroptosis and ultimately improves cardiac function induced by H/R via the HMGB1-TLR4-GPX4 axis. Therefore, we have highlighted a novel mechanism by which GL regulates inflammation, oxidative stress, and ferroptosis via the HMGB1-TLR4-GPX4 pathway to prevent myocardial I/R injury. GL appears to be a potentially applicable drug for the treatment of myocardial I/R injury.

Protein O-GlcNAcylation: The sweet hub in liver metabolic flexibility from a (patho)physiological perspective

O-GlcNAcylation is a dynamic, reversible and atypical O-glycosylation that regulates various cellular physiological processes via conformation, stabilisation, localisation, chaperone interaction or activity of target proteins. The O-GlcNAcylation cycle is precisely controlled by collaboration between O-GlcNAc transferase and O-GlcNAcase. Uridine-diphosphate-N-acetylglucosamine, the sole donor of O-GlcNAcylation produced by the hexosamine biosynthesis pathway, is controlled by the input of glucose, glutamine, acetyl coenzyme A and uridine triphosphate, making it a sensor of the fluctuation of molecules, making O-GlcNAcylation a pivotal nutrient sensor for the metabolism of carbohydrates, amino acids, lipids and nucleotides. O-GlcNAcylation, particularly prevalent in liver, is the core hub for controlling systemic glucose homeostasis due to its nutritional sensitivity and precise spatiotemporal regulation of insulin signal transduction. The pathology of various liver diseases has highlighted hepatic metabolic disorder and dysfunction, and abnormal O-GlcNAcylation also plays a specific pathological role in these processes. Therefore, this review describes the unique features of O-GlcNAcylation and its dynamic homeostasis maintenance. Additionally, it explains the underlying nutritional sensitivity of O-GlcNAcylation and discusses its mechanism of spatiotemporal modulation of insulin signal transduction and liver metabolic homeostasis during the fasting and feeding cycle. This review emphasises the pathophysiological implications of O-GlcNAcylation in nonalcoholic fatty liver disease, nonalcoholic steatohepatitis and hepatic fibrosis, and focuses on the adverse effects of hyper O-GlcNAcylation on liver cancer progression and metabolic reprogramming.

O-GlcNAcylation: cellular physiology and therapeutic target for human diseases

O-linked-β-N-acetylglucosamine (O-GlcNAcylation) is a distinctive posttranslational protein modification involving the coordinated action of O-GlcNAc transferase and O-GlcNAcase, primarily targeting serine or threonine residues in various proteins. This modification impacts protein functionality, influencing stability, protein-protein interactions, and localization. Its interaction with other modifications such as phosphorylation and ubiquitination is becoming increasingly evident. Dysregulation of O-GlcNAcylation is associated with numerous human diseases, including diabetes, nervous system degeneration, and cancers. This review extensively explores the regulatory mechanisms of O-GlcNAcylation, its effects on cellular physiology, and its role in the pathogenesis of diseases. It examines the implications of aberrant O-GlcNAcylation in diabetes and tumorigenesis, highlighting novel insights into its potential role in cardiovascular diseases. The review also discusses the interplay of O-GlcNAcylation with other protein modifications and its impact on cell growth and metabolism. By synthesizing current research, this review elucidates the multifaceted roles of O-GlcNAcylation, providing a comprehensive reference for future studies. It underscores the potential of targeting the O-GlcNAcylation cycle in developing novel therapeutic strategies for various pathologies.

The role of glycolytic metabolic pathways in cardiovascular disease and potential therapeutic approaches

Cardiovascular disease (CVD) is a major threat to human health, accounting for 46% of non-communicable disease deaths. Glycolysis is a conserved and rigorous biological process that breaks down glucose into pyruvate, and its primary function is to provide the body with the energy and intermediate products needed for life activities. The non-glycolytic actions of enzymes associated with the glycolytic pathway have long been found to be associated with the development of CVD, typically exemplified by metabolic remodeling in heart failure, which is a condition in which the heart exhibits a rapid adaptive response to hypoxic and hypoxic conditions, occurring early in the course of heart failure. It is mainly characterized by a decrease in oxidative phosphorylation and a rise in the glycolytic pathway, and the rise in glycolysis is considered a hallmark of metabolic remodeling. In addition to this, the glycolytic metabolic pathway is the main source of energy for cardiomyocytes during ischemia-reperfusion. Not only that, the auxiliary pathways of glycolysis, such as the polyol pathway, hexosamine pathway, and pentose phosphate pathway, are also closely related to CVD. Therefore, targeting glycolysis is very attractive for therapeutic intervention in CVD. However, the relationship between glycolytic pathway and CVD is very complex, and some preclinical studies have confirmed that targeting glycolysis does have a certain degree of efficacy, but its specific role in the development of CVD has yet to be explored. This article aims to summarize the current knowledge regarding the glycolytic pathway and its key enzymes (including hexokinase (HK), phosphoglucose isomerase (PGI), phosphofructokinase-1 (PFK1), aldolase (Aldolase), phosphoglycerate metatase (PGAM), enolase (ENO) pyruvate kinase (PKM) lactate dehydrogenase (LDH)) for their role in cardiovascular diseases (e.g., heart failure, myocardial infarction, atherosclerosis) and possible emerging therapeutic targets.

Dexmedetomidine Ameliorates Cardiac Ischemia/Reperfusion Injury by Enhancing Autophagy Through Activation of the AMPK/SIRT3 Pathway

Objective

Myocardial ischemia-reperfusion (I/R) injury is a detrimental disease, resulting in high morbidity and mortality globally. In this study, we aimed to investigate the role of Dex in mitigating cardiac I/R injury.

Methods

H9c2 cells were treated with Dex (1 μM) for 24 h followed by oxygen-glucose deprivation/re-oxygenation (OGD/R). ANP and BNP mRNA of H9c2 cells and the LDH release were measured. Apoptosis of H9c2 cells was analyzed by flow cytometry. Mitochondrial membrane potential and superoxide production were detected by JC-1 staining and MitoSOXTM Red, respectively. Cell aerobic respiration was measured using Seahorse analysis. In vivo, mice were injected with Dex (25 μg/kg, i.p., once daily) for 5 days and then subjected to heart I/R. Heart function was analyzed by echocardiography. CK-MB and LDH were measured by Elisa. Infarct size was measured using TTC-Evans blue staining. Mitochondrial ultrastructure was observed using transmission electron microscopy. DHE staining, SOD activity, the content of MDA, and the content of GSH/GSSG of heart were measured to evaluate the oxidative stress. In addition, inflammatory cytokines were measured in vivo and in vitro. Furthermore, AMPK, SIRT3, and autophagy-related protein expression in the heart were detected by Western blot.

Results

Dex reduced the H9c2 cells injury exposed to OGD/R, accompanied by improved mitochondrial function and membrane potential. In vivo, Dex improved heart function, myocardial injury, and the mitochondria ultrastructure following I/R injury. Meanwhile, Dex inhibited myocardial oxidative stress and inflammation in the myocardial I/R. Furthermore, Compound C (an AMPK inhibitor) could inhibit Dex-induced autophagy in the I/R heart and the 3-MA (an autophagy inhibitor) could partially interfere with the effects of Dex on the protection of I/R heart.

Conclusion

Dex suppressed oxidative stress and inflammation by promoting autophagy through activating the AMPK/SIRT3 pathway, thus protecting the heart against the I/R injury.

Small extracellular vesicles delivering lncRNA WAC-AS1 aggravate renal allograft ischemia‒reperfusion injury by inducing ferroptosis propagation

Ferroptosis is a predominant contributor to renal ischemia reperfusion injury (IRI) after kidney transplant, evoking delayed graft function and poorer long-term outcomes. The wide propagation of ferroptosis among cell populations in a wave-like manner, developing the "wave of ferroptosis" causes a larger area of tubular necrosis and accordingly aggravates renal allograft IRI. In this study, we decipher a whole new metabolic mechanism underlying ferroptosis and propose a novel spreading pathway of the "wave of ferroptosis" in the renal tissue microenvironment, in which renal IRI cell-secreted small extracellular vesicles (IRI-sEVs) delivering lncRNA WAC-AS1 reprogram glucose metabolism in adjacent renal tubular epithelial cell populations by inducing GFPT1 expression and increasing hexosamine biosynthesis pathway (HBP) flux, and consequently enhances O-GlcNAcylation. Additionally, BACH2 O-GlcNAcylation at threonine 389 in renal tubular epithelial cells prominently inhibits its degradation by ubiquitination and promotes importin α5-mediated nuclear translocation. We present the first evidence that intranuclear BACH2 suppresses SLC7A11 and GPX4 transcription by binding to their proximal promoters and decreases cellular anti-peroxidation capability, accordingly facilitating ferroptosis. Inhibition of sEV biogenesis and secretion by GW4869 and knockout of lncRNA WAC-AS1 in IRI-sEVs both unequivocally diminished the "wave of ferroptosis" propagation and protected against renal allograft IRI. The functional and mechanistic regulation of IRI-sEVs was further corroborated in an allograft kidney transplant model and an in situ renal IRI model. In summary, these findings suggest that inhibiting sEV-mediated lncRNA WAC-AS1 secretion and targeting HBP metabolism-induced BACH2 O-GlcNAcylation in renal tubular epithelial cells may serve as new strategies for protecting against graft IRI after kidney transplant.

Protein O-GlcNAcylation in multiple immune cells and its therapeutic potential

O-GlcNAcylation is a post-translational modification of proteins that involves the addition of O-GlcNAc to serine or threonine residues of nuclear or cytoplasmic proteins, catalyzed by O-GlcNAc transferase (OGT). This modification is highly dynamic and can be reversed by O-GlcNAcase (OGA). O-GlcNAcylation is widespread in the immune system, which engages in multiple physiologic and pathophysiologic processes. There is substantial evidence indicating that both the hexosamine biosynthesis pathway (HBP) and O-GlcNAcylation are critically involved in regulating immune cell function. However, the precise role of O-GlcNAcylation in the immune system needs to be adequately elucidated. This review offers a thorough synopsis of the present research on protein O-GlcNAcylation, accentuating the molecular mechanisms that control immune cells' growth, maturation, and performance via this PTM.

Nanomedicine-Based Therapeutics for Myocardial Ischemic/Reperfusion Injury

Myocardial ischemic/reperfusion (IR) injury is a global cardiovascular disease with high mortality and morbidity. Therapeutic interventions for myocardial ischemia involve restoring the occluded coronary artery. However, reactive oxygen species (ROS) inevitably impair the cardiomyocytes during the ischemic and reperfusion phases. Antioxidant therapy holds great promise against myocardial IR injury. The current therapeutic methodologies for ROS scavenging depend predominantly on administering antioxidants. Nevertheless, the intrinsic drawbacks of antioxidants limit their further clinical transformation. The use of nanoplatforms with versatile characteristics greatly benefits drug delivery in myocardial ischemic therapy. Nanoplatform-mediated drug delivery significantly improves drug bioavailability, increases therapeutic index, and reduces systemic toxicity. Nanoplatforms can be specifically and reasonably designed to enhance molecule accumulation at the myocardial site. The present review initially summarizes the mechanism of ROS generation during the process of myocardial ischemia. The understanding of this phenomenon will facilitate the advancement of innovative therapeutic strategies against myocardial IR injury. The latest developments in nanomedicine for treating myocardial ischemic injury are then discussed. Finally, the current challenges and perspectives in antioxidant therapy for myocardial IR injury are addressed.

The role of glucose in cardiac physiology and pathophysiology

PURPOSE OF REVIEW

Heart failure is one of the major causes of death worldwide and continues to increase despite therapeutics and pharmacology advances. Fatty acids and glucose are used as ATP-producing fuels in heart to meet its energy demands. However, dysregulation of metabolites' use plays a pivotal role in cardiac diseases. How glucose becomes toxic or drives cardiac dysfunction is incompletely understood. In the present review, we summarize the recent findings on cardiac cellular and molecular events that are driven by glucose during pathologic conditions and potential therapeutic strategies to tackle hyperglycemia-mediated cardiac dysfunction.

RECENT FINDINGS

Several studies have emerged recently, demonstrating that excessive glucose utilization has been correlated with impairment of cellular metabolic homeostasis primarily driven by mitochondrial dysfunction and damage, oxidative stress, and abnormal redox signaling. This disturbance is associated with cardiac remodeling, hypertrophy, and systolic and diastolic dysfunction. Both human and animal heart failure studies, report that glucose is a preferable fuel at the expense of fatty acid oxidation during ischemia and hypertrophy, but the opposite happens in diabetic hearts, which warrants further investigation.

SUMMARY

A better understanding of glucose metabolism and its fate during distinct types of heart disease will contribute to developing novel therapeutic options for the prevention and treatment of heart failure.

Tisp40 prevents cardiac ischemia/reperfusion injury through the hexosamine biosynthetic pathway in male mice

The hexosamine biosynthetic pathway (HBP) produces uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) to facilitate O-linked GlcNAc (O-GlcNAc) protein modifications, and subsequently enhance cell survival under lethal stresses. Transcript induced in spermiogenesis 40 (Tisp40) is an endoplasmic reticulum membrane-resident transcription factor and plays critical roles in cell homeostasis. Here, we show that Tisp40 expression, cleavage and nuclear accumulation are increased by cardiac ischemia/reperfusion (I/R) injury. Global Tisp40 deficiency exacerbates, whereas cardiomyocyte-restricted Tisp40 overexpression ameliorates I/R-induced oxidative stress, apoptosis and acute cardiac injury, and modulates cardiac remodeling and dysfunction following long-term observations in male mice. In addition, overexpression of nuclear Tisp40 is sufficient to attenuate cardiac I/R injury in vivo and in vitro. Mechanistic studies indicate that Tisp40 directly binds to a conserved unfolded protein response element (UPRE) of the glutamine-fructose-6-phosphate transaminase 1 (GFPT1) promoter, and subsequently potentiates HBP flux and O-GlcNAc protein modifications. Moreover, we find that I/R-induced upregulation, cleavage and nuclear accumulation of Tisp40 in the heart are mediated by endoplasmic reticulum stress. Our findings identify Tisp40 as a cardiomyocyte-enriched UPR-associated transcription factor, and targeting Tisp40 may develop effective approaches to mitigate cardiac I/R injury.

Ferroptosis: From regulation of lipid peroxidation to the treatment of diseases

Ferroptosis is a regulated cell death mainly manifested by iron-dependent lipid peroxide accumulation. The leading cause of ferroptosis is the imbalance of intracellular oxidative systems (e.g., LOXs, POR, ROS) and antioxidant systems (e.g., GSH/GPx4, CoQ10/FSP1, BH4/GCH1), which is regulated by a complex network. In the past decade, this metabolic network has been continuously refined, and the links with various pathophysiological processes have been gradually established. Apoptosis has been regarded as the only form of regulated cell death for a long time, and the application of chemotherapeutic drugs to induce apoptosis of cancer cells is the mainstream method. However, studies have reported that cancer cells' key features are resistance to apoptosis and chemotherapeutics. For high proliferation, cancer cells often have very active lipid metabolism and iron metabolism, which pave the way for ferroptosis. Interestingly, researchers found that drug-resistant or highly aggressive cancer cells are more prone to ferroptosis. Therefore, ferroptosis may be a potential strategy to eliminate cancer cells. In addition, links between ferroptosis and other diseases, such as neurological disorders and ischemia-reperfusion injury, have also been found. Understanding these diseases from the perspective of ferroptosis may provide new insights into clinical treatment. Herein, the metabolic processes in ferroptosis are reviewed, and the potential mechanisms and targets of ferroptosis in different diseases are summarized.

Sarcopenia and cardiovascular diseases: A systematic review and meta-analysis

Sarcopenia is an age-related disease and is often accompanied by other diseases. Now, many studies have shown that cardiovascular diseases (CVDs) may raise the incidence rate of sarcopenia. Therefore, the purpose of this study was to conduct a systematic review and meta-analysis to investigate the prevalence of sarcopenia in patients with CVDs compared with the general population, defined as relatively healthy non-hospitalized subjects. The databases of PubMed, Embase, Medline and Web of Science were searched for eligible studies published up to 12 November 2022. Two assessment tools were used to evaluate study quality and the risk of bias. Statistical analysis was conducted using STATA 14.0 and R Version 4.1.2. Thirty-eight out of the 89 629 articles retrieved were included in our review. The prevalence of sarcopenia ranged from 10.1% to 68.9% in patients with CVDs, and the pooled prevalence was 35% (95% confidence interval [95% CI]: 28-42%). The pooled prevalence of sarcopenia was 32% (95% CI: 23-41%) in patients with chronic heart failure (CHF), 61% (95% CI: 49-72%) in patients with acute decompensated heart failure (ADHF), 43% (95% CI: 2-85%) in patients with coronary artery disease, 30% (95% CI: 25-35%) in patients with cardiac arrhythmia (CA), 35% (95% CI: 10-59%) in patients with congenital heart disease and 12% (95% CI: 7-17%) in patients with unclassed CVDs. However, in the general population, the prevalence of sarcopenia varied from 2.9% to 28.6% and the pooled prevalence was 13% (95% CI: 9-17%), suggesting that the prevalence of sarcopenia in patients with CVDs was about twice compared with the general population. The prevalence of sarcopenia was significantly higher only in patients with ADHF, CHF and CA compared with the general population. There is a positive correlation between CVDs and sarcopenia. The prevalence of sarcopenia is higher in patients with CVDs than that in the general population. With global aging, sarcopenia has brought a heavy burden to individuals and society. Therefore, it is important to identify the populations with high-risk or probable sarcopenia in order to do an early intervention, such as exercise, to counteract or slow down the progress of sarcopenia.

Abnormalities of glucose and lipid metabolism in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury is a common condition in cardiovascular diseases, and the mechanism of its occurrence involves multiple complex metabolic pathways and signaling pathways. Among these pathways, glucose metabolism and lipid metabolism play important roles in regulating myocardial energy metabolism. Therefore, this article focuses on the roles of glucose metabolism and lipid metabolism in myocardial ischemia-reperfusion injury, including glycolysis, glucose uptake and transport, glycogen metabolism and the pentose phosphate pathway; and triglyceride metabolism, fatty acid uptake and transport, phospholipid metabolism, lipoprotein metabolism, and cholesterol metabolism. Finally, due to the different alterations and development of glucose metabolism and lipid metabolism in myocardial ischemia-reperfusion, there are also complex interregulatory relationships between them. In the future, modulating the equilibrium between glucose metabolism and lipid metabolism in cardiomyocytes and ameliorating aberrations in myocardial energy metabolism represent highly promising novel strategies for addressing myocardial ischemia-reperfusion injury. Therefore, a comprehensive exploration of glycolipid metabolism can offer novel theoretical and clinical insights into the prevention and treatment of myocardial ischemia-reperfusion injury.

Pathological implications of cellular stress in cardiovascular diseases

Cellular stress has been a key factor in the development of cardiovascular diseases. Major types of cellular stress such as mitochondrial stress, endoplasmic reticulum stress, hypoxia, and replicative stress have been implicated in clinical complications of cardiac patients. The heart is the central regulator of the body by supplying oxygenated blood throughout the system. Impairment of cellular function could lead to heart failure, myocardial infarction, ischemia, and even stroke. Understanding the effect of these distinct types of cellular stress on cardiac function is crucial for the scientific community to understand and develop novel therapeutic approaches. This review will comprehensively explain the different mechanisms of cellular stress and the most recent findings related to stress-induced cardiac dysfunction.

Sulforaphane suppresses paraquat-induced oxidative damage in bovine in vitro-matured oocytes through Nrf2 transduction pathway

Sulforaphane (SFN), a bioactive phytocompound extracted from cruciferous plants, has received increasing attention due to its vital cytoprotective role in eliminating oxidative free radical through activation of nuclear factor erythroid 2-related factor (Nrf2)-mediated signal transduction pathway. This study aims at a better insight into the protective benefit of SFN in attenuating paraquat (PQ)-caused impairment in bovine in vitro-matured oocytes and the possible mechanisms involved therein. Results showed that addition of 1 μM SFN during oocyte maturation obtained higher proportions of matured oocytes and in vitro-fertilized embryos. SFN application attenuated the toxicological effects of PQ on bovine oocytes, as manifested by enhanced extending capability of cumulus cell and increased extrusion proportion of first polar body. Following incubation with SFN, oocytes exposed to PQ exhibited reduced intracellular ROS and lipid accumulation levels, and elevated T-SOD and GSH contents. SFN also effectively inhibited PQ-mediated increase in BAX and CASPASE-3 protein expressions. Besides, SFN promoted the transcription of NRF2 and its downstream antioxidative-related genes GCLC, GCLM, HO-1, NQO-1, and TXN1 in a PQ-exposed environment, indicating that SFN prevents PQ-caused cytotoxicity through activation of Nrf2 signal transduction pathway. The mechanisms underlying the role of SFN against PQ-induced injury included the inhibition of TXNIP protein and restoration of the global O-GlcNAc level. Collectively, these findings provide novel evidence for the protective role of SFN in alleviating PQ-caused injury, and suggest that SFN application may be an efficacious intervention strategy against PQ cytotoxicity.

Glycometabolism reprogramming: Implications for cardiovascular diseases

Glycometabolism is well known for its roles as the main source of energy, which mainly includes three metabolic pathways: oxidative phosphorylation, glycolysis and pentose phosphate pathway. The orderly progress of glycometabolism is the basis for the maintenance of cardiovascular function. However, upon exposure to harmful stimuli, the intracellular glycometabolism changes or tends to shift toward another glycometabolism pathway more suitable for its own development and adaptation. This shift away from the normal glycometabolism is also known as glycometabolism reprogramming, which is commonly related to the occurrence and aggravation of cardiovascular diseases. In this review, we elucidate the physiological role of glycometabolism in the cardiovascular system and summarize the mechanisms by which glycometabolism drives cardiovascular diseases, including diabetes, cardiac hypertrophy, heart failure, atherosclerosis, and pulmonary hypertension. Collectively, directing GMR back to normal glycometabolism might provide a therapeutic strategy for the prevention and treatment of related cardiovascular diseases.

Protein O-GlcNAcylation in cardiovascular diseases

O-GlcNAcylation is a post-translational modification of protein in response to genetic variations or environmental factors, which is controlled by two highly conserved enzymes, i.e. O-GlcNAc transferase (OGT) and protein O-GlcNAcase (OGA). Protein O-GlcNAcylation mainly occurs in the cytoplasm, nucleus, and mitochondrion, and it is ubiquitously implicated in the development of cardiovascular disease (CVD). Alterations of O-GlcNAcylation could cause massive metabolic imbalance and affect cardiovascular function, but the role of O-GlcNAcylation in CVD remains controversial. That is, acutely increased O-GlcNAcylation is an adaptive heart response, which temporarily protects cardiac function. While it is harmful to cardiomyocytes if O-GlcNAcylation levels remain high in chronic conditions or in the long run. The underlying mechanisms include regulation of transcription, energy metabolism, and other signal transduction reactions induced by O-GlcNAcylation. In this review, we will focus on the interactions between protein O-GlcNAcylation and CVD, and discuss the potential molecular mechanisms that may be able to pave a new avenue for the treatment of cardiovascular events.

Glutamine promotes O-GlcNAcylation of G6PD and inhibits AGR2 S-glutathionylation to maintain the intestinal mucus barrier in burned septic mice

Mucus forms the first line of defence of the intestinal mucosa barrier, and mucin is its core component. Glutamine is a vital energy substance for goblet cells; it can promote mucus synthesis and alleviate damage to the intestinal mucus barrier after burn injury, but its mechanism is not fully understood. This study focused on the molecular mechanisms underlying the effects of glutamine on the synthesis and modification of mucin 2 (MUC2) by using animal and cellular models of burn sepsis. We found that anterior gradient-2 (AGR2) plays a key role in the posttranslational modification of MUC2. Oxidative stress induced by burn sepsis enhanced the S-glutathionylation of AGR2, interfered with the processing and modification of MUC2 precursors by AGR2 and blocked the synthesis of mature MUC2. Further studies revealed that NADPH, catalysed by glucose-6-phosphate dehydrogenase (G6PD), is a key molecule in inhibiting oxidative stress and regulating AGR2 activity. Glutamine promotes O-linked N-acetylglucosamine (O-GlcNAc) modification of G6PD via the hexosamine pathway, which facilitates G6PD homodimer formation and increases NADPH synthesis, thereby inhibiting AGR2 S-glutathionylation and promoting MUC2 maturation, ultimately reducing damage to the intestinal mucus barrier after burn sepsis. Overall, we have demonstrated that the central mechanisms of glutamine in promoting MUC2 maturation and maintaining the intestinal mucus barrier are the enhancement of G6PD glycosylation and inhibition of AGR2 S-glutathionylation.

Storax Attenuates Cardiac Fibrosis following Acute Myocardial Infarction in Rats via Suppression of AT1R-Ankrd1-P53 Signaling Pathway

Myocardial fibrosis following acute myocardial infarction (AMI) seriously affects the prognosis and survival rate of patients. This study explores the role and regulation mechanism of storax, a commonly used traditional Chinese medicine for treatment of cardiovascular diseases, on myocardial fibrosis and cardiac function. The AMI rat model was established by subcutaneous injection of Isoproterenol hydrochloride (ISO). Storax (0.1, 0.2, 0.4 g/kg) was administered by gavage once/d for 7 days. Electrocardiogram, echocardiography, hemodynamic and cardiac enzyme in AMI rats were measured. HE, Masson, immunofluorescence and TUNEL staining were used to observe the degree of pathological damage, fibrosis and cardiomyocyte apoptosis in myocardial tissue, respectively. Expression of AT1R, CARP and their downstream related apoptotic proteins were detected by WB. The results demonstrated that storax could significantly improve cardiac electrophysiology and function, decrease serum cardiac enzyme activity, reduce type I and III collagen contents to improve fibrosis and alleviate myocardial pathological damage and cardiomyocyte apoptosis. It also found that storax can significantly down-regulate expression of AT1R, Ankrd1, P53, P-p53 (ser 15), Bax and cleaved Caspase-3 and up-regulate expression of Mdm2 and Bcl-2. Taken together, these findings indicated that storax effectively protected cardiomyocytes against myocardial fibrosis and cardiac dysfunction by inhibiting the AT1R-Ankrd1-P53 signaling pathway.

Hypoxia-triggered O-GlcNAcylation in the brain drives the glutamate-glutamine cycle and reduces sensitivity to sevoflurane in mice

BACKGROUND

Hypersensitivity to general anaesthetics predicts adverse postoperative outcomes in patients. Hypoxia exerts extensive pathophysiological effects on the brain; however, whether hypoxia influences sevoflurane sensitivity and its underlying mechanisms remain poorly understood.

METHODS

Mice were acclimated to hypoxia (oxygen 10% for 8 h day^-1) for 28 days and anaesthetised with sevoflurane; the effective concentrations for 50% of the animals (EC₅₀) showing loss of righting reflex (LORR) and loss of tail-pinch withdrawal response (LTWR) were determined. Positron emission tomography-computed tomography, O-glycoproteomics, seahorse analysis, carbon-13 tracing, site-specific mutagenesis, and electrophysiological techniques were performed to explore the underlying mechanisms.

RESULTS

Compared with the control group, the hypoxia-acclimated mice required higher concentrations of sevoflurane to present LORR and LTWR (EC50_LORR: 1.61 [0.03]% vs 1.46 [0.04]%, P<0.01; EC50_LTWR: 2.46 [0.14]% vs 2.22 [0.06]%, P<0.01). Hypoxia-induced reduction in sevoflurane sensitivity was correlated with elevation of protein O-linked N-acetylglucosamine (O-GlcNAc) modification in brain, especially in the thalamus, and could be abolished by 6-diazo-5-oxo-l-norleucine, a glutamine fructose-6-phosphate amidotransferase inhibitor, and mimicked by thiamet-G, a selective O-GlcNAcase inhibitor. Mechanistically, O-GlcNAcylation drives de novo synthesis of glutamine from glucose in astrocytes and promotes the glutamate-glutamine cycle, partially via glycolytic flux and activation of glutamine synthetase.

CONCLUSIONS

Intermittent hypoxia exposure decreased mouse sensitivity to sevoflurane anaesthesia through enhanced O-GlcNAc-dependent modulation of the glutamate-glutamine cycle in the brain.

Aberrant branched-chain amino acid catabolism in cardiovascular diseases

Globally, cardiovascular diseases are the leading cause of death. Research has focused on the metabolism of carbohydrates, fatty acids, and amino acids to improve the prognosis of cardiovascular diseases. There are three types of branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) required for protein homeostasis, energy balance, and signaling pathways. Increasing evidence has implicated BCAAs in the pathogenesis of multiple cardiovascular diseases. This review summarizes the biological origin, signal transduction pathways and function of BCAAs as well as their significance in cardiovascular diseases, including myocardial hypertrophy, heart failure, coronary artery disease, diabetic cardiomyopathy, dilated cardiomyopathy, arrhythmia and hypertension.

Guanxin V alleviates acute myocardial infarction by restraining oxidative stress damage, apoptosis, and fibrosis through the TGF-β1 signalling pathway

BACKGROUND

Oxidative stress, apoptosis, and fibrosis have important roles in acute myocardial infarction, which is the main cause of global morbidity and mortality. Guanxin V significantly ameliorates acute myocardial infarction, the underlying mechanism, however, is still unclear.

PURPOSE

In this study, we detected the anti-oxidative, anti-apoptotic, and anti-fibrosis effects of Guanxin V on acute myocardial infarction.

METHODS

We used left anterior descending coronary artery ligation to construct an acute myocardial infarction model. Cardiac function, heart weight, infarction size, and histopathology were measured. Cardiomyocytes were treated with hydrogen peroxide to build an in vitro model. Cell apoptosis, fibrosis, and reactive oxygen species-related markers were tested. We observed the mitochondrial ultrastructure through transmission electron microscopy. The levels of collagens and TGF-β1 signalling were measured. The lentiviral vector containing the full-length TGF-β1 sequence was administered to investigate the rescue role of Guanxin V.

RESULTS

Guanxin V significantly decreased apoptosis and inhibited oxidative stress damage and fibrosis in acute myocardial infarction. Hydrogen peroxide could stimulate cardiomyocytes to produce reactive oxygen species and Guanxin V could significantly reverse hydrogen peroxide-induced cell damage, inhibit oxidative stress damage, apoptosis, and fibrosis, and enhance mitochondrial dynamic balance. Mechanistically, Guanxin V attenuated oxidative stress damage, apoptosis, and fibrosis induced by the TGF-β1 signalling pathway activation.

CONCLUSIONS

Guanxin V effectively relieved apoptosis, oxidative stress damage, and fibrosis through down-regulating the TGF-β1 signalling pathway, which enhances the knowledge of the cellular and molecular mechanism of Guanxin V in treating acute myocardial infarction.

O-GlcNAcylation: The Underestimated Emerging Regulators of Skeletal Muscle Physiology

O-GlcNAcylation is a highly dynamic, reversible and atypical glycosylation that regulates the activity, biological function, stability, sublocation and interaction of target proteins. O-GlcNAcylation receives and coordinates different signal inputs as an intracellular integrator similar to the nutrient sensor and stress receptor, which target multiple substrates with spatio-temporal analysis specifically to maintain cellular homeostasis and normal physiological functions. Our review gives a brief description of O-GlcNAcylation and its only two processing enzymes and HBP flux, which will help to better understand its physiological characteristics of sensing nutrition and environmental cues. This nutritional and stress-sensitive properties of O-GlcNAcylation allow it to participate in the precise regulation of skeletal muscle metabolism. This review discusses the mechanism of O-GlcNAcylation to alleviate metabolic disorders and the controversy about the insulin resistance of skeletal muscle. The level of global O-GlcNAcylation is precisely controlled and maintained in the "optimal zone", and its abnormal changes is a potential factor in the pathogenesis of cancer, neurodegeneration, diabetes and diabetic complications. Although the essential role of O-GlcNAcylation in skeletal muscle physiology has been widely studied and recognized, it still is underestimated and overlooked. This review highlights the latest progress and potential mechanisms of O-GlcNAcylation in the regulation of skeletal muscle contraction and structural properties.

Mitochondrial DNA Is a Vital Driving Force in Ischemia-Reperfusion Injury in Cardiovascular Diseases

According to the latest Global Burden of Disease Study, cardiovascular disease (CVD) is the leading cause of death, and ischemic heart disease and stroke are the cause of death in approximately half of CVD patients. In CVD, mitochondrial dysfunction following ischemia-reperfusion (I/R) injury results in heart failure. The proper functioning of oxidative phosphorylation (OXPHOS) and the mitochondrial life cycle in cardiac mitochondria are closely related to mitochondrial DNA (mtDNA). Following myocardial I/R injury, mitochondria activate multiple repair and clearance mechanisms to repair damaged mtDNA. When these repair mechanisms are insufficient to restore the structure and function of mtDNA, irreversible mtDNA damage occurs, leading to mtDNA mutations. Since mtDNA mutations aggravate OXPHOS dysfunction and affect mitophagy, mtDNA mutation accumulation leads to leakage of mtDNA and proteins outside the mitochondria, inducing an innate immune response, aggravating cardiovascular injury, and leading to the need for external interventions to stop or slow the disease course. On the other hand, mtDNA released into the circulation after cardiac injury can serve as a biomarker for CVD diagnosis and prognosis. This article reviews the pathogenic basis and related research findings of mtDNA oxidative damage and mtDNA leak-triggered innate immune response associated with I/R injury in CVD and summarizes therapeutic options that target mtDNA.

Obesity by High-Fat Diet Increases Pain Sensitivity by Reprogramming Branched-Chain Amino Acid Catabolism in Dorsal Root Ganglia

Obesity is a significant health concern as a result of poor-quality diet, for example, high-fat diet (HFD). Although multiple biological and molecular changes have been identified to contribute to HFD-induced pain susceptibility, the mechanisms are not fully understood. Here, we show that mice under 8 weeks of HFD were sensitive to mechanical and thermal stimuli, which was coupled with an accumulation of branched-chain amino acids (BCAAs) in lumbar dorsal root ganglia (DRG) due to local BCAA catabolism deficiency. This HFD-induced hyperalgesic phenotype could be exacerbated by supply of excessive BCAAs or mitigated by promotion of BCAA catabolism via BT2 treatment. In addition, our results suggested that HFD-related pain hypersensitivity was associated with a pro-inflammatory status in DRG, which could be regulated by BCAA abundance. Therefore, our study demonstrates that defective BCAA catabolism in DRG facilitates HFD-induced pain hypersensitivity by triggering inflammation. These findings not only reveal metabolic underpinnings for the pathogenesis of HFD-related hyperalgesia but also offer potential targets for developing diet-based therapy of chronic pain.

Ageing Increases Cardiac Electrical Remodelling in Rats and Mice via NOX4/ROS/CaMKII-Mediated Calcium Signalling

Objective

Ageing is one of the risk factors associated with cardiovascular diseases including cardiac arrhythmias and heart failure. Ageing-related cardiac dysfunction involves a complicated pathophysiological progress. Abnormal membrane voltage and Ca²⁺ dynamics in aged cardiomyocytes contribute to ageing-related arrhythmias. However, its underlying mechanisms have not been well clarified.

Methods

Young and old rats or mice were included in this study. Cardiac electrophysiological properties and functions were assessed by ECG, echocardiography, and ex vivo heart voltage and Ca²⁺ optical mapping. Proteomics, phosphor-proteomics, Western blotting, Masson staining, and ROS measurement were used to investigate the underlying mechanisms.

Results

Ageing increased the incidence of cardiac hypertrophy and fibrosis in rats. Moreover, ageing increased the occurrence of ventricular tachycardia or ventricular fibrillation induced by rapid pacing and during isoprenaline (ISO) (1 mg/kg i.p.) challenge in mice in vivo. Optical mapping with dual dyes (membrane voltage (V_m) dye and intracellular Ca²⁺ dye) simultaneously recording revealed that ageing increased the action potential duration (APD) and Ca²⁺ transient duration (CaTD) and slowed the ventricular conduction with the Langendorff-perfused mouse heart. More importantly, ageing increased the ISO-induced (1 μM) changes of APD (ΔAPD80) and CaTD (ΔCaTD50). Ageing also delayed the decay of Ca²⁺ transient by extending the decay time constant from 30% to 90% (τ₃₀₋₉₀). In addition, ageing decreased the V_m/Ca²⁺ latency which represented the coupling of V_m/Ca²⁺ including between the midpoint of AP depolarization and Ca²⁺ upstroke, peak transmembrane voltage and peak cytosolic calcium, and time to 50% voltage repolarization and extrusion of cytosolic calcium. Optical mapping also revealed that ageing increased the ISO-induced arrhythmia incidence and occurrence of the excitation rotor. Proteomics and phosphor-proteomics assays from rat hearts demonstrated ageing-induced protein and phosphor-protein changes, suggesting that CaMKII was involved in ageing-induced change. Ageing increased the level of ROS and the expression of NOX4, oxidative CaMKII (ox-CaMKII), phosphorated CaMKII (p-CaMKII), and periostin.

Conclusion

Ageing accelerates cardiac remodelling and increases the susceptibility to ventricular arrhythmias through NOX4/ROS/CaMKII pathway-mediated abnormal membrane voltage and intracellular Ca²⁺ handling and V_m/Ca²⁺ coupling.

Hypoxia Acclimation Protects against Heart Failure Postacute Myocardial Infarction via Fundc1-Mediated Mitophagy

Mitochondrial dysfunction is the main cause of heart failure (HF) postacute myocardial infarction (AMI). Hypoxia acclimation (HA) reduces efficiently the area of AMI caused by ischemia and/or reperfusion and delays HF. Here, we examined whether HA improves mitochondrial structure and function through the hypoxic autophagy receptor FUNDC1 to prevent HF post-AMI. Male adult mice were acclimated in a low-pressure hypoxic animal chamber (11% oxygen (O2)) for 8 h/day for 28 days, and then, an induced HF post-AMI model via left anterior descending (LAD) artery ligation was structured to explore the efficacy and mechanism of HA. Our results showed that HA exposure can improve cardiac structure and function in mice with HF post-AMI and protected myocardial mitochondrial morphology and function. Further studies showed that HA increased the expression of Fundc1 protein and its associated mitophagy protein LC3 in myocardial tissue after infarction. We then established a cellular model of oxygen glucose deprivation (OGD) in vitro, and knockdown of FUNDC1 attenuated the protective effect of HA exposed on cardiomyocyte mitochondria and increased cardiomyocyte apoptosis. In conclusion, the protective effect of HA on HF post-AMI is achieved by regulating Fundc1-mediated mitophagy in myocardial tissue. FUNDC1-mediated mitophagy could be a promising strategy to treat cardiovascular diseases, including HF.

Ketone Body β-Hydroxybutyrate Prevents Myocardial Oxidative Stress in Septic Cardiomyopathy

Septic cardiomyopathy is a life-threatening complication of severe sepsis and septic shock. Oxidative stress and mitochondrial dysfunction have been identified as significant abnormalities in septic cardiomyopathy. However, specific treatments are rare. This study aims to investigate the impact of β-hydroxybutyrate (β-OHB) on septic cardiomyopathy and explore the underlying mechanism(s). We found that pretreatment of D-β-hydroxybutyrate-(R)-1,3 butanediol monoester (ketone ester, 3 mg/g body weight, once daily) by gavage for three days elevated the levels of ketone bodies, especially that of β-hydroxybutyrate (β-OHB) in the circulation and mouse hearts, which exerted a protective effect against lipopolysaccharide (LPS, 20 mg/kg)-induced septic cardiomyopathy in mice. In addition, an LPS-stimulated macrophage-conditioned medium (MCM) was used to mimic the pathological process of septic cardiomyopathy. Mechanistically, β-OHB alleviated myocardial oxidative stress and improved mitochondrial respiratory function through the antioxidant FoxO3a/MT2 pathway activated via histone deacetylase (HDAC) inhibition, which ultimately enhanced heart performance in septic cardiomyopathy. Our results, therefore, suggested an unappreciated critical role of β-OHB in septic heart protection as well as highlighted the potential of β-OHB as a simple remedy for the septic cardiomyopathy population.

Mitochondrial protein hyperacetylation underpins heart failure with preserved ejection fraction in mice

Over 50% of patients with heart failure have preserved ejection fraction (HFpEF), rather than reduced ejection fraction (HFrEF). The prevalence of HFpEF continues to increase, while the pathogenic mechanisms underlying HFpEF remain largely elusive and evidence-based therapies are still lacking. This study was designed to investigate the metabolic signature of HFpEF and test the potential therapeutic intervention in a mouse model. By utilizing a "3-Hit" HFpEF mouse model, we observed a global protein hyperacetylation in the HFpEF hearts as compared to the pressure overload-induced HFrEF and adult/aged non-heart failure (NHF) hearts. Acetylome analysis identified that a large proportion of the hyperacetylated proteins (74%) specific to the HFpEF hearts are in mitochondria, and enriched in tricarboxylic acid (TCA) cycle, oxidative phosphorylation (OXPHOS), and fatty acid oxidation. Further study showed that the elevated protein acetylation in the HFpEF hearts was correlated with reduced NAD⁺/NADH ratio, impaired mitochondrial function, and depleted TCA cycle metabolites. Normalization of NAD⁺/NADH ratio by supplementation of nicotinamide riboside (NR) for 30 days downregulated the acetylation level, improved mitochondrial function and ameliorated HFpEF phenotypes. Therefore, our study identified a distinct protein acetylation pattern in the HFpEF hearts, and proposed NR as a promising agent in lowering acetylation and mitigating HFpEF phenotypes in mice.

The dual role of the hexosamine biosynthetic pathway in cardiac physiology and pathophysiology

The heart is a highly metabolic organ with extensive energy demands and hence relies on numerous fuel substrates including fatty acids and glucose. However, oxidative stress is a natural by-product of metabolism that, in excess, can contribute towards DNA damage and poly-ADP-ribose polymerase activation. This activation inhibits key glycolytic enzymes, subsequently shunting glycolytic intermediates into non-oxidative glucose pathways such as the hexosamine biosynthetic pathway (HBP). In this review we provide evidence supporting the dual role of the HBP, i.e. playing a unique role in cardiac physiology and pathophysiology where acute upregulation confers cardioprotection while chronic activation contributes to the onset and progression of cardio-metabolic diseases such as diabetes, hypertrophy, ischemic heart disease, and heart failure. Thus although the HBP has emerged as a novel therapeutic target for such conditions, proposed interventions need to be applied in a context- and pathology-specific manner to avoid any potential drawbacks of relatively low cardiac HBP activity.

Mitochondrial Metabolism in Myocardial Remodeling and Mechanical Unloading: Implications for Ischemic Heart Disease

Ischemic heart disease refers to myocardial degeneration, necrosis, and fibrosis caused by coronary artery disease. It can lead to severe left ventricular dysfunction (LVEF ≤ 35–40%) and is a major cause of heart failure (HF). In each contraction, myocardium is subjected to a variety of mechanical forces, such as stretch, afterload, and shear stress, and these mechanical stresses are clinically associated with myocardial remodeling and, eventually, cardiac outcomes. Mitochondria produce 90% of ATP in the heart and participate in metabolic pathways that regulate the balance of glucose and fatty acid oxidative phosphorylation. However, altered energetics and metabolic reprogramming are proved to aggravate HF development and progression by disturbing substrate utilization. This review briefly summarizes the current insights into the adaptations of cardiomyocytes to mechanical stimuli and underlying mechanisms in ischemic heart disease, with focusing on mitochondrial metabolism. We also discuss how mechanical circulatory support (MCS) alters myocardial energy metabolism and affects the detrimental metabolic adaptations of the dysfunctional myocardium.

Enhancement of O-GlcNAcylation on Mitochondrial Proteins with 2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-d-pyranoside, Contributes to the Mitochondrial Network, Cellular Bioenergetics and Stress Response in Neuronal Cells under Ischemic-like Conditions

O-GlcNAcylation is a nutrient-driven post-translational modification known as a metabolic sensor that links metabolism to cellular function. Recent evidences indicate that the activation of O-GlcNAc pathway is a potential pro-survival pathway and that acute enhancement of this response is conducive to the survival of cells and tissues. 2-(4-Methoxyphenyl)ethyl-2-acetamido-2-deoxy-β-d-pyranoside (SalA-4g), is a salidroside analogue synthesized in our laboratory by chemical structure-modification, with a phenyl ring containing a para-methoxy group and a sugar ring consisting of N-acetylglucosamine. We have previously shown that SalA-4g elevates levels of protein O-GlcNAc and improves neuronal tolerance to ischemia. However, the specific target of SalA-4g regulating O-GlcNAcylation remains unknown. To address these questions, in this study, we have focused on mitochondrial network homeostasis mediated by O-GlcNAcylation in SalA-4g’s neuroprotection in primary cortical neurons under ischemic-like conditions. O-GlcNAc-modified mitochondria induced by SalA-4g demonstrated stronger neuroprotection under oxygen glucose deprivation and reoxygenation stress, including the improvement of mitochondrial homeostasis and bioenergy, and inhibition of mitochondrial apoptosis pathway. Blocking mitochondrial protein O-GlcNAcylation with OSMI-1 disrupted mitochondrial network homeostasis and antagonized the protective effects of SalA-4g. Collectively, these data demonstrate that mitochondrial homeostasis mediated by mitochondrial protein O-GlcNAcylation is critically involved in SalA-4g neuroprotection.