Calcium Signaling and Reactive Oxygen Species in Mitochondria

Composite dietary antioxidant index and the risk of heart failure: A cross-sectional study from NHANES

BACKGROUND

Previous studies show that oxidative stress is important in heart failure (HF) pathogenesis. The composite dietary antioxidant index (CDAI), which reflects the antioxidant profile of nutrient supplements, is associated with cardiovascular mortality risk. However, the association between CDAI and the risk of HF remains unknown.

HYPOTHESIS

In this study, we investigated the relationship between CDAI and HF risk using National Health and Nutritional Examination Survey (NHANES) data.

METHODS

The data of participants aged >40 years old from the NHNANES between 2001 and 2018 were obtained and used to assess the relationship between CDAI and the risk of HF. Logistic regression was used to calculate the odds ratio (OR) of CDAI for the risk of HF.

RESULTS

A total of 29 101 participants were divided into the HF (n = 1419; 4.88%) and non-HF groups (n = 27 682; 95.12%), HF group participants had lower CDAI than the non-HF group (-0.32 ± 0.14 vs. 0.67 ± 0.05, p < .0001). Compared with the lowest CDAI quartile (Q1), the OR for HF risk was 0.88 (0.68-1.13) for Q2 (p = .30), 0.77 (0.61-0.99) for Q3 (p = .04), and 0.68 (0.52-0.89) for Q4 (p = .01).

CONCLUSIONS

CDAI was negatively associated with the risk of HF. Our findings show that the intake of an antioxidant-rich dietary is a potential method to reduce the risk of HF.

Activation of the integrated stress response rewires cardiac metabolism in Barth syndrome

Barth Syndrome (BTHS) is an inherited cardiomyopathy caused by defects in the mitochondrial transacylase TAFAZZIN (Taz), required for the synthesis of the phospholipid cardiolipin. BTHS is characterized by heart failure, increased propensity for arrhythmias and a blunted inotropic reserve. Defects in Ca2+-induced Krebs cycle activation contribute to these functional defects, but despite oxidation of pyridine nucleotides, no oxidative stress developed in the heart. Here, we investigated how retrograde signaling pathways orchestrate metabolic rewiring to compensate for mitochondrial defects. In mice with an inducible knockdown (KD) of TAFAZZIN, and in induced pluripotent stem cell-derived cardiac myocytes, mitochondrial uptake and oxidation of fatty acids was strongly decreased, while glucose uptake was increased. Unbiased transcriptomic analyses revealed that the activation of the eIF2α/ATF4 axis of the integrated stress response upregulates one-carbon metabolism, which diverts glycolytic intermediates towards the biosynthesis of serine and fuels the biosynthesis of glutathione. In addition, strong upregulation of the glutamate/cystine antiporter xCT increases cardiac cystine import required for glutathione synthesis. Increased glutamate uptake facilitates anaplerotic replenishment of the Krebs cycle, sustaining energy production and antioxidative pathways. These data indicate that ATF4-driven rewiring of metabolism compensates for defects in mitochondrial uptake of fatty acids to sustain energy production and antioxidation.

Health position paper and redox perspectives on reactive oxygen species as signals and targets of cardioprotection

The present review summarizes the beneficial and detrimental roles of reactive oxygen species in myocardial ischemia/reperfusion injury and cardioprotection. In the first part, the continued need for cardioprotection beyond that by rapid reperfusion of acute myocardial infarction is emphasized. Then, pathomechanisms of myocardial ischemia/reperfusion to the myocardium and the coronary circulation and the different modes of cell death in myocardial infarction are characterized. Different mechanical and pharmacological interventions to protect the ischemic/reperfused myocardium in elective percutaneous coronary interventions and coronary artery bypass grafting, in acute myocardial infarction and in cardiotoxicity from cancer therapy are detailed. The second part keeps the focus on ROS providing a comprehensive overview of molecular and cellular mechanisms involved in ischemia/reperfusion injury. Starting from mitochondria as the main sources and targets of ROS in ischemic/reperfused myocardium, a complex network of cellular and extracellular processes is discussed, including relationships with Ca2+ homeostasis, thiol group redox balance, hydrogen sulfide modulation, cross-talk with NAPDH oxidases, exosomes, cytokines and growth factors. While mechanistic insights are needed to improve our current therapeutic approaches, advancements in knowledge of ROS-mediated processes indicate that detrimental facets of oxidative stress are opposed by ROS requirement for physiological and protective reactions. This inevitable contrast is likely to underlie unsuccessful clinical trials and limits the development of novel cardioprotective interventions simply based upon ROS removal.

TRPV1 Channels Are New Players in the Reticulum-Mitochondria Ca2+ Coupling in a Rat Cardiomyoblast Cell Line

The Ca2+ release in microdomains formed by intercompartmental contacts, such as mitochondria-associated endoplasmic reticulum membranes (MAMs), encodes a signal that contributes to Ca2+ homeostasis and cell fate control. However, the composition and function of MAMs remain to be fully defined. Here, we focused on the transient receptor potential vanilloid 1 (TRPV1), a Ca2+-permeable ion channel and a polymodal nociceptor. We found TRPV1 channels in the reticular membrane, including some at MAMs, in a rat cardiomyoblast cell line (SV40-transformed H9c2) by Western blotting, immunostaining, cell fractionation, and proximity ligation assay. We used chemical and genetic probes to perform Ca2+ imaging in four cellular compartments: the endoplasmic reticulum (ER), cytoplasm, mitochondrial matrix, and mitochondrial surface. Our results showed that the ER Ca2+ released through TRPV1 channels is detected at the mitochondrial outer membrane and transferred to the mitochondria. Finally, we observed that prolonged TRPV1 modulation for 30 min alters the intracellular Ca2+ equilibrium and influences the MAM structure or the hypoxia/reoxygenation-induced cell death. Thus, our study provides the first evidence that TRPV1 channels contribute to MAM Ca2+ exchanges.

d-Limonene complexed with cyclodextrin attenuates cardiac arrhythmias in an experimental model of doxorubicin-induced cardiotoxicity: Possible involvement of calcium/calmodulin-dependent protein kinase type II

BACKGROUND

Arrhythmias are one manifestation of the cardiotoxicity that results from doxorubicin (Doxo) administration. Although cardiotoxicity is an anticipated outcome in anticancer therapies, there is still a lack of treatment options available for its effective management. This study sought to evaluate the possible cardioprotective effect of complex d-limonene (DL) plus hydroxypropyl-β-cyclodextrin (HβDL) during treatment with Doxo, focusing on the arrhythmic feature.

METHODS

Cardiotoxicity was induced in Swiss mice with Doxo 20 mg/kg, with 10 mg/kg of HβDL being administered 30 min before the Doxo. Plasma CK-MB and LDH levels were analyzed. Cellular excitability and susceptibility to cardiac and cardiomyocyte arrhythmias were evaluated using in vivo (pharmacological cardiac stress) and in vitro (burst pacing) ECG protocols. Ca2+ dynamics were also investigated. The expression of CaMKII and its activation by phosphorylation and oxidation were evaluated by western blot, and molecular docking was used to analyze the possible interaction between DL and CaMKII.

RESULTS

Electrocardiograms showed that administration of 10 mg/kg of HβDL prevented Doxo-induced widening of the QRS complex and QT interval. HβDL also prevented cardiomyocyte electrophysiological changes that trigger cellular arrhythmias, such as increases in action potential duration and variability; decreased the occurrence of delayed afterdepolarizations (DADs) and triggered activities (TAs), and reduced the incidence of arrhythmia in vivo. Ca2+ waves and CaMKII overactivation caused by phosphorylation and oxidation were also decreased. In the in silico study, DL showed potential inhibitory interaction with CaMKII.

CONCLUSION

Our results show that 10 mg/kg of βDL protects the heart against Doxo-induced cardiotoxicity arrhythmias, and that this is probably due to its inhibitory effect on CaMKII hyperactivation.

Platelet mitochondria: the mighty few

PURPOSE OF REVIEW

Platelet mitochondrial dysfunction is both caused by, as well as a source of oxidative stress. Oxidative stress is a key hallmark of metabolic disorders such as dyslipidemia and diabetes, which are known to have higher risks for thrombotic complications.

RECENT FINDINGS

Increasing evidence supports a critical role for platelet mitochondria beyond energy production and apoptosis. Mitochondria are key regulators of reactive oxygen species and procoagulant platelets, which both contribute to pathological thrombosis. Studies targeting platelet mitochondrial pathways have reported promising results suggesting antithrombotic effects with limited impact on hemostasis in animal models.

SUMMARY

Targeting platelet mitochondria holds promise for the reduction of thrombotic complications in patients with metabolic disorders. Future studies should aim at validating these preclinical findings and translate them to the clinic.

Long-term exposure to polystyrene microplastics triggers premature testicular aging

BACKGROUND

Plastic pollution is greatly serious in the ocean and soil. Microplastics (MPs) degraded from plastic has threatened animals and humans health. The accumulation of MPs in the tissues and blood in animals and humans has been found. There is therefore a need to assess the toxicological effects of MPs on the reproductive system.

RESULTS

In this study, we explored the effect of polystyrene microplastics (PS-MPs) on premature testicular aging in vitro and in vivo. In vitro, we found that testicular sertoli cells (TM4 cells) was prematurely senescent following PS-MPs treatment by the evaluation of a range of aging marker molecules (such as Sa-β-gal, p16 and 21). TM4 cells were then employed for in vitro model to study the potential molecular mechanism by which PS-MPs induce the premature senescence of TM4 cells. NF-κB is identified as a key molecule for PS-MPs-induced TM4 cellular senescence. Furthermore, through eliminating reactive oxygen species (ROS), the activation of nuclear factor kappa B (NF-κB) was blocked in PS-MPs-induced senescent TM4 cells, indicating that ROS triggers NF-κB activation. Next, we analyzed the causes of mitochondrial ROS (mtROS) accumulation induced by PS-MPs, and results showed that Ca2+ overload induced the accumulation of mtROS. Further, PS-MPs exposure inhibits mitophagy, leading to the continuous accumulation of senescent cells. In vivo, 8-week-old C57 mice were used as models to assess the effect of PS-MPs on premature testicular aging. The results illustrated that PS-MPs exposure causes premature aging of testicular tissue by testing aging markers. Additionally, PS-MPs led to oxidative stress and inflammatory response in the testicular tissue.

CONCLUSION

In short, our experimental results revealed that PS-MPs-caused testicular premature aging is dependent on Ca2+/ROS/NF-κB signaling axis. The current study lays the foundation for further exploration of the effects of microplastics on testicular toxicology.

Ryanodine receptor 2 inhibition reduces dispersion of cardiac repolarization, improves contractile function and prevents sudden arrhythmic death in failing hearts

Introduction

Sudden cardiac death (SCD) from ventricular tachycardia/fibrillation (VT/VF) are a leading cause of death, but current therapies are limited. Despite extensive research on drugs targeting sarcolemmal ion channels, none have proven sufficiently effective for preventing SCD. Sarcoplasmic ryanodine receptor 2 (RyR2) Ca 2+ release channels, the downstream effectors of sarcolemmal ion channels, are underexplored in this context. Recent evidence implicates reactive oxygen species (ROS)- mediated oxidation and hyperactivity of RyR2s in the pathophysiology of SCD.

Objective

To test the hypothesis that RyR2 inhibition of failing arrhythmogenic hearts reduces sarcoplasmic Ca 2+ leak and repolarization lability, mitigates VT/VF/SCD and improves contractile function.

Methods

We used a guinea pig model that replicates key clinical aspects of human nonischemic HF, such as a prolonged QT interval, a high prevalence of spontaneous arrhythmic SCD, and profound Ca 2+ leak via a hyperactive RyR2. HF animals were randomized to receive dantrolene (DS) or placebo in early or chronic HF. We assessed the incidence of VT/VF and SCD (primary outcome), ECG heart rate and QT variability, echocardiographic left ventricular (LV) structure and function, immunohistochemical LV fibrosis, and sarcoplasmic RyR2 oxidation.

Results

DS treatment prevented VT/VF and SCD by decreasing dispersion of repolarization and ventricular arrhythmias. Compared to placebo, DS lowered resting heart rate, preserved chronotropic competency during transient β-adrenergic challenge, and improved heart rate variability and cardiac function.

Conclusion

Inhibition of RyR2 hyperactivity with dantrolene mitigates the vicious cycle of sarcoplasmic Ca 2+ leak-induced increases in diastolic Ca 2+ and ROS-mediated RyR2 oxidation, thereby increasing repolarization lability and protecting against VT/VF/SCD. Moreover, the consequent increase in sarcoplasmic Ca 2+ load improves contractile function. These potentially life-saving effects of RyR2 inhibition warrant further investigation, such as clinical studies of repurposing dantrolene as a potential new therapy for heart failure and/or SCD.

Mitochondria as a therapeutic: a potential new frontier in driving the shift from tissue repair to regeneration

Fibrosis, or scar tissue development, is associated with numerous pathologies and is often considered a worst-case scenario in terms of wound healing or the implantation of a biomaterial. All that remains is a disorganized, densely packed and poorly vascularized bundle of connective tissue, which was once functional tissue. This creates a significant obstacle to the restoration of tissue function or integration with any biomaterial. Therefore, it is of paramount importance in tissue engineering and regenerative medicine to emphasize regeneration, the successful recovery of native tissue function, as opposed to repair, the replacement of the native tissue (often with scar tissue). A technique dubbed 'mitochondrial transplantation' is a burgeoning field of research that shows promise in in vitro, in vivo and various clinical applications in preventing cell death, reducing inflammation, restoring cell metabolism and proper oxidative balance, among other reported benefits. However, there is currently a lack of research regarding the potential for mitochondrial therapies within tissue engineering and regenerative biomaterials. Thus, this review explores these promising findings and outlines the potential for mitochondrial transplantation-based therapies as a new frontier of scientific research with respect to driving regeneration in wound healing and host-biomaterial interactions, the current successes of mitochondrial transplantation that warrant this potential and the critical questions and remaining obstacles that remain in the field.

Multifaceted role of redox pattern in the tumor immune microenvironment regarding autophagy and apoptosis

The reversible oxidation-reduction homeostasis mechanism functions as a specific signal transduction system, eliciting related physiological responses. Disruptions to redox homeostasis can have negative consequences, including the potential for cancer development and progression, which are closely linked to a series of redox processes, such as adjustment of reactive oxygen species (ROS) levels and species, changes in antioxidant capacity, and differential effects of ROS on downstream cell fate and immune capacity. The tumor microenvironment (TME) exhibits a complex interplay between immunity and regulatory cell death, especially autophagy and apoptosis, which is crucially regulated by ROS. The present study aims to investigate the mechanism by which multi-source ROS affects apoptosis, autophagy, and the anti-tumor immune response in the TME and the mutual crosstalk between these three processes. Given the intricate role of ROS in controlling cell fate and immunity, we will further examine the relationship between traditional cancer therapy and ROS. It is worth noting that we will discuss some potential ROS-related treatment options for further future studies.

A high-salt diet promotes hypertrophic scarring through TRPC3-mediated mitochondrial Ca2+ homeostasis dysfunction

Diet High in salt content have been associated with cardiovascular disease and chronic inflammation. We recently demonstrated that transient receptor potential canonical 3 (TRPC3) channels regulate myofibroblast transdifferentiation in hypertrophic scars. Here, we examined how high salt activation of TRPC3 participates in hypertrophic scarring during wound healing. In vitro, we confirmed that high salt increased the TRPC3 protein expression and the marker of myofibroblast alpha smooth muscle actin (α-SMA) in wild-type mice (WT) primary cultured dermal fibroblasts but not Trpc3-/- mice. Activation of TRPC3 by high salt elevated cytosolic Ca2+ influx and mitochondrial Ca2+ uptake in dermal fibroblasts in a TRPC3-dependent manner. High salt activation of TRPC3 enhanced mitochondrial respiratory dysfunction and excessive ROS production by inhibiting pyruvate dehydrogenase action, that activated ROS-triggered Ca2+ influx and the Rho kinase/MLC pathway in WT mice but not Trpc3-/- mice. In vivo, a persistent high-salt diet promoted myofibroblast transdifferentiation and collagen deposition in a TRPC3-dependent manner. Therefore, this study demonstrates that high salt enhances myofibroblast transdifferentiation and promotes hypertrophic scar formation through enhanced mitochondrial Ca2+ homeostasis, which activates the ROS-mediated pMLC/pMYPT1 pathway. TRPC3 deficiency antagonizes high salt diet-induced hypertrophic scarring. TRPC3 may be a novel target for hypertrophic scarring during wound healing.

Distinct Effects of Mitochondrial Na+/Ca2+ Exchanger Inhibition and Ca2+ Uniporter Activation on Ca2+ Sparks and Arrhythmogenesis in Diabetic Rats

Background Mitochondrial dysfunction contributes to the cardiac remodeling triggered by type 2 diabetes (T2D). Mitochondrial Ca2+ concentration ([Ca2+]m) modulates the oxidative state and cytosolic Ca2+ regulation. Thus, we investigated how T2D affects mitochondrial Ca2+ fluxes, the downstream consequences on myocyte function, and the effects of normalizing mitochondrial Ca2+ transport. Methods and Results We compared myocytes/hearts from transgenic rats with late-onset T2D (rats that develop late-onset T2D due to heterozygous expression of human amylin in the pancreatic β-cells [HIP] model) and their nondiabetic wild-type (WT) littermates. [Ca2+]m was significantly lower in myocytes from diabetic HIP rats compared with WT cells. Ca2+ extrusion through the mitochondrial Na+/Ca2+ exchanger (mitoNCX) was elevated in HIP versus WT myocytes, particularly at moderate and high [Ca2+]m, while mitochondrial Ca2+ uptake was diminished. Mitochondrial Na+ concentration was comparable in WT and HIP rat myocytes and remained remarkably stable while manipulating mitoNCX activity. Lower [Ca2+]m was associated with oxidative stress, increased sarcoplasmic reticulum Ca2+ leak in the form of Ca2+ sparks, and mitochondrial dysfunction in T2D hearts. MitoNCX inhibition with CGP-37157 reduced oxidative stress, Ca2+ spark frequency, and stress-induced arrhythmias in HIP rat hearts while having no significant effect in WT rats. In contrast, activation of the mitochondrial Ca2+ uniporter with SB-202190 enhanced spontaneous sarcoplasmic reticulum Ca2+ release and had no significant effect on arrhythmias in both WT and HIP rat hearts. Conclusions [Ca2+]m is reduced in myocytes from rats with T2D due to a combination of exacerbated mitochondrial Ca2+ extrusion through mitoNCX and impaired mitochondrial Ca2+ uptake. Partial mitoNCX inhibition limits sarcoplasmic reticulum Ca2+ leak and arrhythmias in T2D hearts, whereas mitochondrial Ca2+ uniporter activation does not.

Ca2+ pushes and pulls energetics to maintain ATP balance in atrial cells: computational insights

To maintain atrial function, ATP supply-to-demand matching must be tightly controlled. Ca²⁺ can modulate both energy consumption and production. In light of evidence suggesting that Ca²⁺ affects energetics through "push" (activating metabolite flux and enzymes in the Krebs cycle to push the redox flux) and "pull" (acting directly on ATP synthase and driving the redox flux through the electron transport chain and increasing ATP production) pathways, we investigated whether both pathways are necessary to maintain atrial ATP supply-to-demand matching. Rabbit right atrial cells were electrically stimulated at different rates, and oxygen consumption and flavoprotein fluorescence were measured. To gain mechanistic insight into the regulators of ATP supply-to-demand matching in atrial cells, models of atrial electrophysiology, Ca²⁺ cycling and force were integrated with a model of mitochondrial Ca²⁺ and a modified model of mitochondrial energy metabolism. The experimental results showed that oxygen consumption increased in response to increases in the electrical stimulation rate. The model reproduced these findings and predicted that the increase in oxygen consumption is associated with metabolic homeostasis. The model predicted that Ca²⁺ must act both in "push" and "pull" pathways to increase oxygen consumption. In contrast to ventricular trabeculae, no rapid time-dependent changes in mitochondrial flavoprotein fluorescence were measured upon an abrupt change in workload. The model reproduced these findings and predicted that the maintenance of metabolic homeostasis is due to the effects of Ca²⁺ on ATP production. Taken together, this work provides evidence of Ca²⁺ "push" and "pull" activity to maintain metabolic homeostasis in atrial cells.

Micronutrients/miRs/ATP networking in mitochondria: Clinical intervention with ferroptosis, cuproptosis, and calcium burden

The mitochondrial electron transport chain (mtETC) requires mainly coenzyme Q10 (CoQ10), copper (Cu2+), calcium (Ca2+), and iron (Fe2+) ions for efficient ATP production. According to cross-sectional research, up to 50% of patients with micronutrient imbalances have been linked to oxidative stress, mitochondrial dysfunction, reduced ATP production, and the prognosis of various diseases. The condition of ferroptosis, which is caused by the downregulation of CoQ10 and the activation of non-coding micro RNAs (miRs), is strongly linked to free radical accumulation, cancer, and neurodegenerative diseases. The entry of micronutrients into the mitochondrial matrix depends upon the higher threshold level of mitochondrial membrane potential (ΔΨm), and high cytosolic micronutrients. The elevated micronutrient in the mitochondrial matrix causes the utilization of all ATP, leading to a drop in ATP levels. Mitochondrial calcium uniporter (MCU) and Na+/Ca2+ exchanger (NCX) play a major role in Ca2+ influx in the mitochondrial matrix. The mitochondrial Ca2+ overload is regulated by specific miRs such as miR1, miR7, miR25, miR145, miR138, and miR214, thereby reducing apoptosis and improving ATP production. Cuproptosis is primarily brought on by increased Cu+ build-up and mitochondrial proteotoxic stress, mediated by ferredoxin-1 (FDX1) and long non-coding RNAs. Cu importers (SLC31A1) and exporters (ATP7B) influence intracellular Cu2+ levels to control cuproptosis. According to literature reviews, very few randomized micronutrient interventions have been carried out, despite the identification of a high prevalence of micronutrient deficiencies. In this review, we concentrated on essential micronutrients and specific miRs associated with ATP production that balance oxidative stress in mitochondria.

Mitochondrial quality control in cardiac fibrosis: Epigenetic mechanisms and therapeutic strategies

Cardiac fibrosis (CF) is considered an ultimate common pathway of a wide variety of heart diseases in response to diverse pathological and pathophysiological stimuli. Mitochondria are characterized as isolated organelles with a double-membrane structure, and they primarily contribute to and maintain highly dynamic energy and metabolic networks whose distribution and structure exert potent support for cellular properties and performance. Because the myocardium is a highly oxidative tissue with high energy demands to continuously pump blood, mitochondria are the most abundant organelles within mature cardiomyocytes, accounting for up to one-third of the total cell volume, and play an essential role in maintaining optimal performance of the heart. Mitochondrial quality control (MQC), including mitochondrial fusion, fission, mitophagy, mitochondrial biogenesis, and mitochondrial metabolism and biosynthesis, is crucial machinery that modulates cardiac cells and heart function by maintaining and regulating the morphological structure, function and lifespan of mitochondria. Certain investigations have focused on mitochondrial dynamics, including manipulating and maintaining the dynamic balance of energy demand and nutrient supply, and the resultant findings suggest that changes in mitochondrial morphology and function may contribute to bioenergetic adaptation during cardiac fibrosis and pathological remodeling. In this review, we discuss the function of epigenetic regulation and molecular mechanisms of MQC in the pathogenesis of CF and provide evidence for targeting MQC for CF. Finally, we discuss how these findings can be applied to improve the treatment and prevention of CF.

Mitochondrial calcium and reactive oxygen species in cardiovascular disease

Cardiomyocytes are one of the most mitochondria-rich cell types in the body, with ∼30-40% of the cell volume being composed of mitochondria. Mitochondria are well established as the primary site of adenosine triphosphate (ATP) generation in a beating cardiomyocyte, generating up to 90% of its ATP. Mitochondria have many functions in the cell, which could contribute to susceptibility to and development of cardiovascular disease (CVD). Mitochondria are key players in cell metabolism, ATP production, reactive oxygen species (ROS) production, and cell death. Mitochondrial calcium (Ca2+) plays a critical role in many of these pathways, and thus the dynamics of mitochondrial Ca2+ are important in regulating mitochondrial processes. Alterations in these varied and in many cases interrelated functions play an important role in CVD. This review will focus on the interrelationship of mitochondrial energetics, Ca2+, and ROS and their roles in CVD. Recent insights into the regulation and dysregulation of these pathways have led to some novel therapeutic approaches.

Immunomodulatory role of non-ionizing electromagnetic radiation in human leukemiamonocytic cell line

In daily life, people are usually exposed to radiofrequency radiations (RFR). The effects of RFR on human physiology have been a major source of controversy since the WHO declared that these radiations are a type of environmental energy that interacts with the physiological functioning of the human body. The immune system provides internal protection and promotes long-term health and survival. However, the relevant research on the innate immune system and radiofrequency radiation is scant. In this connection, we hypothesized that innate immune responses would be influenced by exposure to non-ionizing electromagnetic radiation from mobile phones in a cell-specific and time-dependent manner. To analyze this hypothesis, human leukemia monocytic cell lines were exposed to 2318 MHz (MHz) RFR emitted by mobile phones at a power density of 0.224 W/m² in a controlled manner for various time durations (15, 30, 45, 60, 90, and 120 min). Systematic studies on cell viability, nitric oxide (NO), superoxide (SO), pro-inflammatory cytokine production, and phagocytic assays were performed after the irradiation. The duration of exposure seems to have a substantial influence on the RFR-induced effects. It was noticed that after 30 min of exposure, the RFR dramatically enhanced the pro-inflammatory cytokine IL-1α level as well as reactive species such as NO and SO generation as compared to the control. In contrast, the RFR dramatically reduced the phagocytic activity of monocytes during 60 min of treatment when compared to the control. Interestingly, the irradiated cells restored their normal functioning until the final 120-min of exposure. Furthermore, mobile phone exposure had no influence on cell viability or TNF-α level. The results showed that RFR exhibits a time-dependent immune-modulatory role in the human leukemia monocytic cell line. Nevertheless, more research is needed to further determine the long-term effects and precise mechanism of action of RFR.

The Potential of Cylindromatosis (CYLD) as a Therapeutic Target in Oxidative Stress-Associated Pathologies: A Comprehensive Evaluation

Oxidative stress (OS) arises as a consequence of an imbalance between the formation of reactive oxygen species (ROS) and the capacity of antioxidant defense mechanisms to neutralize them. Excessive ROS production can lead to the damage of critical biomolecules, such as lipids, proteins, and DNA, ultimately contributing to the onset and progression of a multitude of diseases, including atherosclerosis, chronic obstructive pulmonary disease, Alzheimer's disease, and cancer. Cylindromatosis (CYLD), initially identified as a gene linked to familial cylindromatosis, has a well-established and increasingly well-characterized function in tumor inhibition and anti-inflammatory processes. Nevertheless, burgeoning evidence suggests that CYLD, as a conserved deubiquitination enzyme, also plays a pivotal role in various key signaling pathways and is implicated in the pathogenesis of numerous diseases driven by oxidative stress. In this review, we systematically examine the current research on the function and pathogenesis of CYLD in diseases instigated by oxidative stress. Therapeutic interventions targeting CYLD may hold significant promise for the treatment and management of oxidative stress-induced human diseases.

Targeting Mitochondrial Metabolism to Save the Failing Heart

Despite considerable progress in treating cardiac disorders, the prevalence of heart failure (HF) keeps growing, making it a global medical and economic burden. HF is characterized by profound metabolic remodeling, which mostly occurs in the mitochondria. Although it is well established that the failing heart is energy-deficient, the role of mitochondria in the pathophysiology of HF extends beyond the energetic aspects. Changes in substrate oxidation, tricarboxylic acid cycle and the respiratory chain have emerged as key players in regulating myocardial energy homeostasis, Ca²⁺ handling, oxidative stress and inflammation. This work aims to highlight metabolic alterations in the mitochondria and their far-reaching effects on the pathophysiology of HF. Based on this knowledge, we will also discuss potential metabolic approaches to improve cardiac function.

Cardiac Metabolism in Heart Failure and Implications for Uremic Cardiomyopathy

Chronic kidney disease is associated with an increased risk for the development and progression of cardiovascular disorders including hypertension, dyslipidemia, and coronary artery disease. Chronic kidney disease may also affect the myocardium through complex systemic changes, resulting in structural remodeling such as hypertrophy and fibrosis, as well as impairments in both diastolic and systolic function. These cardiac changes in the setting of chronic kidney disease define a specific cardiomyopathic phenotype known as uremic cardiomyopathy. Cardiac function is tightly linked to its metabolism, and research over the past 3 decades has revealed significant metabolic remodeling in the myocardium during the development of heart failure. Because the concept of uremic cardiomyopathy has only been recognized in recent years, there are limited data on metabolism in the uremic heart. Nonetheless, recent findings suggest overlapping mechanisms with heart failure. This work reviews key features of metabolic remodeling in the failing heart in the general population and extends this to patients with chronic kidney disease. The knowledge of similarities and differences in cardiac metabolism between heart failure and uremic cardiomyopathy may help identify new targets for mechanistic and therapeutic research on uremic cardiomyopathy.

A Novel Three-Dimensional Follicle Culture System Decreases Oxidative Stress and Promotes the Prolonged Culture of Human Granulosa Cells

Tissue engineering advancements have made it possible to modify biomaterials to reconstruct a similar three-dimensional structure of the extracellular matrix (ECM) for follicle development and to supply the required biological signals. We postulated that an artificial polysaccharide hydrogel modified with an ECM mimetic peptide may produce efficient irritation signals by binding to specific integrins providing a suitable environment for follicular development and influencing the behavior of human granulosa cells (hGCs). Laminin, an important component of the extracellular matrix, can modulate hGCs and oocyte growth. Specifically, follicles of mice were randomly divided into two-dimensional (2D) and three-dimensional (3D) culture systems established by a hydrogel modified with RGD or laminin mimetic peptides (IKVAV and YIGSR) and RGD (IYR). Our results showed that 3D cultured systems significantly improved follicle survival, growth, and viability. IYR peptides enhanced the oocyte meiosis competence. Additionally, we explored the effect of 3D culture on hGCs, which improved hGCs viability, increased the proportion of S- and G2/M-phase cells, and inhibited cell apoptosis of hGCs. On days 1 and 2, the secretion of progesterone was reduced in 3D-cultured hGCs. Notably, 3D-cultured hGCs exhibited delayed senescence, decreased oxidative stress, and elevated mitochondrial membrane potential. Moreover, the expression levels of cumulus expansion-related genes (COX2, HAS2, and PTX3) and integrin α6β1 were upregulated in 3D-cultured hGCs. In conclusion, a 3D culture utilizing hydrogels modified with Laminin-mimetic peptides can provide a durable physical environment suitable for follicular development. The laminin-mimetic peptides may regulate the biological activity of hGCs by attaching to the integrin α6β1.

Syntaxin17 contributes to obesity cardiomyopathy through promoting mitochondrial Ca2+ overload in a Parkin-MCUb-dependent manner

OBJECTIVE

Uncorrected obesity is accompanied by unfavorable structural and functional changes in the heart, known as obesity cardiomyopathy. Recent evidence has revealed a crucial role for mitochondria-associated endoplasmic reticulum membranes (MAMs) in obesity-induced cardiac complication. Syntaxin 17 (STX17) serves as a scaffolding molecule localized on MAMs although its role in obesity heart complication remains elusive.

METHODS AND MATERIALS

This study examined the role of STX17 in MAMs and mitochondrial Ca²⁺ homeostasis in HFD-induced obesity cardiomyopathy using tamoxifen-induced cardiac-specific STX17 knockout (STX17^cko) and STX17 overexpression mice using intravenously delivered recombinant adeno-associated virus serotype-9 (AAV9-cTNT-STX17).

RESULTS

STX17 levels were significantly elevated in plasma from obese patients and heart tissues of HFD-fed mice. Our data revealed that cardiac STX17 knockout alleviated cardiac remodeling and dysfunction in obese hearts without eliciting any notable effect itself, while STX17 overexpression aggravated cardiac dysfunction in obese mice. STX17 deletion and STX17 overexpression annihilated and aggravated, respectively, HFD-induced oxidative stress (O₂^- production) and mitochondrial injury in the heart. Furthermore, STX17 transfection facilitated obesity-induced MAMs formation in cardiomyocytes and evoked excess mitochondrial Ca²⁺ influx, dependent upon interaction with mitochondrial Ca²⁺ uniporter dominant negative β (MCUb) through Habc domain. Our data also suggested that STX17 promoted ubiquitination and degradation of MCUb through the E3 ligase parkin in the face of palmitate challenging.

CONCLUSION

Taken together, our results identified a novel role for STX17 in facilitating obesity-induced MAMs formation, and subsequently mitochondrial Ca²⁺ overload, mitochondrial O₂^- accumulation, lipid peroxidation, resulting in cardiac impairment. Our findings denoted therapeutic promises of targeting STX17 in obesity.

PDE3A and GSK3B as Atrial Fibrillation Susceptibility Genes in the Chinese Population via Bioinformatics and Genome-Wide Association Analysis

Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia, with uncovered genetic etiology and pathogenesis. We aimed to screen out AF susceptibility genes with potential pathogenesis significance in the Chinese population. Methods: Differentially expressed genes (DEGs) were screened by the Limma package in three GEO data sets of atrial tissue. AF-related genes were identified by combination of DEGs and public GWAS susceptibility genes. Potential drug target genes were selected using the DrugBank, STITCH and TCMSP databases. Pathway enrichment analyses of AF-related genes were performed using the databases GO and KEGG databases. The pathway gene network was visualized by Cytoscape software to identify gene–gene interactions and hub genes. GWAS analysis of 110 cases of AF and 1201 controls was carried out through a genome-wide efficient mixed model in the Fangshan population to verify the results of bioinformatic analysis. Results: A total of 3173 DEGs were identified, 57 of which were found to be significantly associated with of AF in public GWAS results. A total of 75 AF-related genes were found to be potential therapeutic targets. Pathway enrichment analysis selected 79 significant pathways and classified them into 7 major pathway networks. A total of 35 hub genes were selected from the pathway networks. GWAS analysis identified 126 AF-associated loci. PDE3A and GSK3B were found to be overlapping genes between bioinformatic analysis and GWAS analysis. Conclusions: We screened out several pivotal genes and pathways involved in AF pathogenesis. Among them, PDE3A and GSK3B were significantly associated with the risk of AF in the Chinese population. Our study provided new insights into the mechanisms of action of AF.

ATP synthase interactome analysis identifies a new subunit l as a modulator of permeability transition pore in yeast

The mitochondrial ATP synthase, an enzyme that synthesizes ATP and is involved in the formation of the mitochondrial mega-channel and permeability transition, is a multi-subunit complex. In S. cerevisiae, the uncharacterized protein Mco10 was previously found to be associated with ATP synthase and referred as a new 'subunit l'. However, recent cryo-EM structures could not ascertain Mco10 with the enzyme making questionable its role as a structural subunit. The N-terminal part of Mco10 is very similar to k/Atp19 subunit, which along with subunits g/Atp20 and e/Atp21 plays a major role in stabilization of the ATP synthase dimers. In our effort to confidently define the small protein interactome of ATP synthase we found Mco10. We herein investigate the impact of Mco10 on ATP synthase functioning. Biochemical analysis reveal in spite of similarity in sequence and evolutionary lineage, that Mco10 and Atp19 differ significantly in function. The Mco10 is an auxiliary ATP synthase subunit that only functions in permeability transition.

Relationship between Oxidative Stress and Left Ventricle Markers in Patients with Chronic Heart Failure

Oxidative stress is proposed in the literature as an important player in the development of CHF and correlates with left ventricle (LV) dysfunction and hypertrophy in the failing heart. In this study, we aimed to verify if the serum oxidative stress markers differ in chronic heart failure (CHF) patients' groups depending on the LV geometry and function. Patients were stratified into two groups according to left ventricular ejection fraction (LVEF) values: HFrEF (<40% (n = 27)) and HFpEF (≥40% (n = 33)). Additionally, patients were stratified into four groups according to LV geometry: NG-normal left ventricle geometry (n = 7), CR-concentric remodeling (n = 14), cLVH-concentric LV hypertrophy (n = 16), and eLVF-eccentric LV hypertrophy (n = 23). We measured protein (protein carbonyl (PC), nitrotyrosine (NT-Tyr), dityrosine), lipid (malondialdehyde (MDA), oxidizes (HDL) oxidation and antioxidant (catalase activity, total plasma antioxidant capacity (TAC) markers in serum. Transthoracic echocardiogram analysis and lipidogram were also performed. We found that oxidative (NT-Tyr, dityrosine, PC, MDA, oxHDL) and antioxidative (TAC, catalase) stress marker levels did not differ between the groups according to LVEF or LV geometry. NT-Tyr correlated with PC (r_s = 0.482, p = 0.000098), and oxHDL (r_s = 0.278, p = 0.0314). MDA correlated with total (r_s = 0.337, p = 0.008), LDL (r_s = 0.295, p = 0.022) and non-HDL (r_s = 0.301, p = 0.019) cholesterol. NT-Tyr negatively correlated with HDL cholesterol (r_s = -0.285, p = 0.027). LV parameters did not correlate with oxidative/antioxidative stress markers. Significant negative correlations were found between the end-diastolic volume of the LV and the end-systolic volume of the LV and HDL-cholesterol (r_s = -0.935, p < 0.0001; r_s = -0.906, p < 0.0001, respectively). Significant positive correlations between both the thickness of the interventricular septum and the thickness of the LV wall and the levels of triacylglycerol in serum (r_s = 0.346, p = 0.007; r_s = 0.329, p = 0.010, respectively) were found. In conclusions, we did not find a difference in serum concentrations of both oxidant (NT-Tyr, PC, MDA) and antioxidant (TAC and catalase) concentrations in CHF patients' groups according to LV function and geometry was found. The geometry of the LV could be related to lipid metabolism in CHF patients, and no correlation between oxidative/antioxidant and LV markers in CHF patients was found.

Mitochondrial responses to intracellular Ca2+ release following infrared stimulation

Many studies of Ca2+ effects on mitochondrial respiration in intact cells have used electrical and/or chemical stimulation to elevate intracellular [Ca2+], and have reported increases in [NADH] and increased ADP/ATP ratios as dominant controllers of respiration. This study tested a different form of stimulation: brief temperature increases produced by pulses of infrared light (IR, 1,863 nm, 8-10°C for ∼5 s). Fluorescence imaging techniques applied to single PC-12 cells in low µM extracellular [Ca2+] revealed IR stimulation-induced increases in both cytosolic (fluo5F) and mitochondrial (rhod2) [Ca2+]. IR stimulation increased O2 consumption (porphyrin fluorescence), and produced an alkaline shift in mitochondrial matrix pH (Snarf1), indicating activation of the electron transport chain (ETC). The increase in O2 consumption persisted in oligomycin, and began during a decrease in NADH, suggesting that the initial increase in ETC activity was not driven by increased ATP synthase activity or an increased fuel supply to ETC complex I. Imaging with two potentiometric dyes [tetramethyl rhodamine methyl ester (TMRM) and R123] indicated a depolarizing shift in ΔΨm that persisted in high [K+] medium. High-resolution fluorescence imaging disclosed large, reversible mitochondrial depolarizations that were inhibited by cyclosporin A (CSA), consistent with the opening of transient mitochondrial permeability transition pores. IR stimulation also produced a Ca2+-dependent increase in superoxide production (MitoSox) that was not inhibited by CSA, indicating that the increase in superoxide did not require transition pore opening. Thus, the intracellular Ca2+ release that follows pulses of infrared light offers new insights into Ca2+-dependent processes controlling respiration and reactive oxygen species in intact cells.NEW & NOTEWORTHY Pulses of infrared light (IR) provide a novel method for rapidly transferring Ca2+ from the endoplasmic reticulum to mitochondria in intact cells. In PC12 cells the resulting ETC activation was not driven by increased ATP synthase activity or NADH. IR stimulation produced a Ca2+-dependent, reversible depolarization of ΔΨm that was partially blocked by cyclosporin A, and a Ca2+-dependent increase in superoxide that did not require transition pore opening.

Changes in cellular Ca2+ and Na+ regulation during the progression towards heart failure

In adapting to disease and loss of tissue, the heart shows great phenotypic plasticity that involves changes to its structure, composition and electrophysiology. Together with parallel whole body cardiovascular adaptations, the initial decline in cardiac function resulting from the insult is compensated. However, in the long term, the heart muscle begins to fail and patients with this condition have a very poor prognosis, with many dying from disturbances of rhythm. The surviving myocytes of these hearts gain Na+ , which is positively inotropic because of alterations to Ca2+ fluxes mediated by the Na+ /Ca2+ exchange, but compromises Ca2+ -dependent energy metabolism in mitochondria. Uptake of Ca2+ into the sarcoplasmic reticulum (SR) is reduced because of diminished function of SR Ca2+ ATPases. The result of increased Ca2+ influx and reduced SR Ca2+ uptake is an increase in the diastolic cytosolic Ca2+ concentration, which promotes spontaneous SR Ca2+ release and induces delayed afterdepolarisations. Action potential duration prolongs because of increased late Na+ current and changes in expression and function of other ion channels and transporters increasing the probability of the formation of early afterdepolarisations. There is a reduction in T-tubule density and so the normal spatial arrangements required for efficient excitation-contraction coupling are compromised and lead to temporal delays in Ca2+ release from the SR. Therefore, the structural and electrophysiological responses that occur to provide compensation do so at the expense of (1) increasing the likelihood of arrhythmogenesis; (2) activating hypertrophic, apoptotic and Ca2+ signalling pathways; and (3) decreasing the efficiency of SR Ca2+ release.

[Mechano-energetic defects in heart failure]

Heart failure is characterized by defects in excitation-contraction coupling, energetic deficit and oxidative stress. The energy for cardiac contraction and relaxation is provided in mitochondria, whose function is tightly regulated by excitation-contraction coupling in cardiac myocytes. In heart failure with reduced ejection fraction (HFrEF), alterations in the ion balance in cardiac myocytes impair mitochondrial Ca²⁺ uptake, which is required for activation of the Krebs cycle, causing an energetic deficit and oxidative stress in mitochondria. Recent clinical studies suggest that in heart failure with preserved ejection fraction (HFpEF), in stark contrast to HFrEF, hypercontractility often occurs as an attempt to compensate for a pathological increase in systemic and pulmonary vascular resistance. This hypercontractility increases cardiac energy and oxygen demands at rest and reduces the contractile, diastolic and coronary reserves, preventing an adequate increase in cardiac output during exercise. Moreover, increased contractility causes long-term maladaptive remodeling processes due to oxidative stress and redox-sensitive prohypertrophic signaling pathways. As overweight and diabetes, particularly in the interplay with hemodynamic stress, are important risk factors for the development of HFpEF, interventions targeting metabolism in particular could ameliorate the development and progression of HFpEF.

Ginsenoside Rb1 promotes the activation of PPARα pathway via inhibiting FADD to ameliorate heart failure

PURPOSE

Ginsenoside Rb1 (GRb1), a dammarane-type triterpene saponin compound mainly distributed in ginseng (Panax ginseng), has been demonstrated to ameliorate cardiovascular diseases. However, it remains unclear whether GRb1 alleviates heart failure (HF) by maintaining cardiac energy metabolism balance. Therefore, this work aimed to investigate the cardiac benefits of GRb1 against cardiac energy deficit and explore its mechanism of action.

METHODS AND RESULTS

Isoproterenol (ISO) induced HF Sprague-Dawley rats were administrated with GRb1 or fenofibrate for 6 weeks. ISO-induced primary neonatal rat cardiomyocytes (NRCMs) were used as the in vitro model. In vivo, GRb1 significantly improved the structural and metabolic disorder, as demonstrated by the restoration of cardiac function, inhibition of cardiac hypertrophy and fibrosis, and increased adenosine triphosphate (ATP) generation. In vitro, GRb1 effectively protected mitochondrial function and scavenged excessive reactive oxygen species. Moreover, in ISO-induced NRCMs, GRb1 significantly inhibited the abnormal upregulation of Fas-associated death domain (FADD), promoted transcriptional activation of peroxisome proliferator-activated receptor-alpha (PPARα), improved the aberrant expression of cardiac energy metabolism-related enzymes and cardiac fatty acid oxidation, and subsequently increased the synthesis of ATP. Noticeably, GRb1 could inhibit the increased binding between FADD and PPARα, which contributed to the activation of PPARα. Furthermore, GRb1 strengthened the thermal stabilization of FADD and might bind to FADD directly.

CONCLUSIONS

Collectively, it's part of the in-depth mechanism of GRb1's cardio-protection that GRb1 could directly bind to FADD and counteract its negative role in the transcription of PPARα thus ameliorating cardiac energy derangement and HF.

Molecular Mechanisms and Therapeutic Implications of Endothelial Dysfunction in Patients with Heart Failure

Heart failure is a complex medical syndrome that is attributed to a number of risk factors; nevertheless, its clinical presentation is quite similar among the different etiologies. Heart failure displays a rapidly increasing prevalence due to the aging of the population and the success of medical treatment and devices. The pathophysiology of heart failure comprises several mechanisms, such as activation of neurohormonal systems, oxidative stress, dysfunctional calcium handling, impaired energy utilization, mitochondrial dysfunction, and inflammation, which are also implicated in the development of endothelial dysfunction. Heart failure with reduced ejection fraction is usually the result of myocardial loss, which progressively ends in myocardial remodeling. On the other hand, heart failure with preserved ejection fraction is common in patients with comorbidities such as diabetes mellitus, obesity, and hypertension, which trigger the creation of a micro-environment of chronic, ongoing inflammation. Interestingly, endothelial dysfunction of both peripheral vessels and coronary epicardial vessels and microcirculation is a common characteristic of both categories of heart failure and has been associated with worse cardiovascular outcomes. Indeed, exercise training and several heart failure drug categories display favorable effects against endothelial dysfunction apart from their established direct myocardial benefit.

Mitochondrial Dysfunction in Cardiac Arrhythmias

Electrophysiological and structural disruptions in cardiac arrhythmias are closely related to mitochondrial dysfunction. Mitochondria are an organelle generating ATP, thereby satisfying the energy demand of the incessant electrical activity in the heart. In arrhythmias, the homeostatic supply-demand relationship is impaired, which is often accompanied by progressive mitochondrial dysfunction leading to reduced ATP production and elevated reactive oxidative species generation. Furthermore, ion homeostasis, membrane excitability, and cardiac structure can be disrupted through pathological changes in gap junctions and inflammatory signaling, which results in impaired cardiac electrical homeostasis. Herein, we review the electrical and molecular mechanisms of cardiac arrhythmias, with a particular focus on mitochondrial dysfunction in ionic regulation and gap junction action. We provide an update on inherited and acquired mitochondrial dysfunction to explore the pathophysiology of different types of arrhythmias. In addition, we highlight the role of mitochondria in bradyarrhythmia, including sinus node dysfunction and atrioventricular node dysfunction. Finally, we discuss how confounding factors, such as aging, gut microbiome, cardiac reperfusion injury, and electrical stimulation, modulate mitochondrial function and cause tachyarrhythmia.

Genome instability in peripheral blood lymphocytes of patients with heart failure and reduced ejection fraction

Heart failure (HF) is a complex clinical condition characterized by functional and structural defects of the myocardium, but genetic and environmental factors are considered to play an important role in the development of the disease. In the present study, we investigated the genome instability (DNA and chromosomal damage) in patients with heart failure with reduced ejection fraction (HFrEF) ≤40% and its association with risk factors. The studied population included 48 individuals, of which 29 HFrEF patients (mean age 57.41 ± 5.74 years) and 19 healthy controls (mean age 57.63 ± 6.09 years). The genetic damage index in peripheral blood lymphocytes was analyzed using the comet assay, while micronuclei frequency and nuclear division index were analyzed using the cytokinesis-block micronucleus assay. Our results showed that HFrEF patients had a significantly higher genetic damage index compared with the healthy controls (P < .001). Cytokinesis-block micronucleus assay showed that the average micronucleus frequency in peripheral blood lymphocytes of patients was significantly higher, while the nuclear division index values were significantly lower than in controls (P < .01). Using multiple linear regression analysis, pathological state, ejection fraction, creatinine, glucose, associated disease, residence, proBNP, troponin, urea, ACE-inhibitors, and length of the drug therapy were identified as predictors of DNA and/or chromosomal damage in HF patients. We can conclude that DNA and chromosomal damage was increased in patients with HF, which may be a consequence of disease and/or drug therapy.

Cardiac Involvement in Mitochondrial Disorders

PURPOSE OF REVIEW

We review pathophysiology and clinical features of mitochondrial disorders manifesting with cardiomyopathy.

RECENT FINDINGS

Mechanistic studies have shed light into the underpinnings of mitochondrial disorders, providing novel insights into mitochondrial physiology and identifying new therapeutic targets. Mitochondrial disorders are a group of rare genetic diseases that are caused by mutations in mitochondrial DNA (mtDNA) or in nuclear genes that are essential to mitochondrial function. The clinical picture is extremely heterogeneous, the onset can occur at any age, and virtually, any organ or tissue can be involved. Since the heart relies primarily on mitochondrial oxidative metabolism to fuel contraction and relaxation, cardiac involvement is common in mitochondrial disorders and often represents a major determinant of their prognosis.

Nicorandil protects podocytes via modulation of antioxidative capacity in acute puromycin aminonucleoside-induced nephrosis in rats

Nephrotic syndrome, characterized by proteinuria and hypoalbuminemia, results from the dysregulation of glomerular podocytes and is a significant cause of end-stage kidney disease. Patients with idiopathic nephrotic syndrome are generally treated with immunosuppressive agents; however, these agents produce various adverse effects. Previously, we reported the renoprotective effects of a stimulator of the mitochondrial ATP-dependent K⁺ channel (MitK_ATP), nicorandil, in a remnant kidney model. Nonetheless, the cellular targets of these effects remain unknown. Here, we examined the effect of nicorandil on puromycin aminonucleoside-induced nephrosis (PAN) rats, a well-established model of podocyte injury and human nephrotic syndrome. PAN was induced using a single intraperitoneal injection. Nicorandil was administered orally at 30 mg/kg/day. We found that proteinuria and hypoalbuminemia in PAN rats were significantly ameliorated following nicorandil treatment. Immunostaining and ultrastructural analysis under electron microscopy demonstrated that podocyte injury in PAN rats showed a significant partial attenuation following nicorandil treatment. Nicorandil ameliorated the increase in the oxidative stress markers nitrotyrosine and 8-hydroxy-2-deoxyguanosine in glomeruli. Conversely, nicorandil prevented the decrease in levels of the antioxidant enzyme manganese superoxide dismutase in PAN rats. We found that mitochondrial Ca²⁺ uniporter levels in glomeruli were higher in PAN rats than in control rats, and this increase was significantly attenuated by nicorandil. We conclude that stimulation of MitK_ATP by nicorandil reduces proteinuria by attenuating podocyte injury in PAN nephrosis, which restores mitochondrial antioxidative capacity, possibly through mitochondrial Ca²⁺ uniporter modulation. These data indicate that MitK_ATP may represent a novel target for podocyte injury and nephrotic syndrome.NEW & NOTEWORTHY Our findings suggest that the mitochondrial Ca²⁺ uniporter may be an upstream regulator of manganese superoxide dismutase and indicate a biochemical basis for the interaction between the ATP-sensitive K⁺ channel and Ca²⁺ signaling. We believe that our study makes a significant contribution to the literature because our results indicate that the ATP-sensitive K⁺ channel may be a potential therapeutic target for podocyte injury and nephrotic syndrome.

Modulation of the mitochondrial Ca2+ uniporter complex subunit expression by different shear stress patterns in vascular endothelial cells

Mitochondrial calcium (m Ca2+ ) uptake occurs via the Mitochondrial Ca2+ Uniporter (MCU) complex and plays a critical role in mitochondrial dynamics, mitophagy, and apoptosis. MCU complex activity is in part modulated by the expression of its regulatory subunits. Cardiovascular disease models demonstrated altered gene/protein expression of one or multiple subunits in different cells, including vascular endothelial cells (ECs). MCU complex activity was found necessary for stable flow (s-flow)-induced mitophagy and promotion of an atheroprotective EC phenotype. Disturbed flow (d-flow) is known to lead to an atheroprone phenotype. Despite the role of MCU in flow-regulated EC function, flow-induced alterations in MCU complex subunit expression are currently unknown. We exposed cultured human ECs to atheroprotective (steady shear stress, SS) or atheroprone flow (oscillatory shear stress, OS) and measured mRNA and protein levels of the MCU complex members. SS and OS differentially modulated subunit expression at gene/protein levels. Protein expression changes of the core MCU, m Ca2+ uptake 1 (MICU1) and MCU regulator 1 (MCUR1) subunits in SS- and OS-exposed, compared to static, ECs suggested an enhanced m Ca2+ influx under each flow and a potential contribution to EC dysfunction under OS. In silico analysis of a single-cell RNA-sequencing dataset was employed to extract transcript values of MCU subunits in mouse carotid ECs from regions exposed to s-flow or d-flow. Mcu and Mcur1 genes showed significant differences in expression after prolonged exposure to each flow. The differential expression of MCU complex subunits indicated a tight regulation of the complex activity under physiological and pathological hemodynamic conditions.

LACTB induces cancer cell death through the activation of the intrinsic caspase-independent pathway in breast cancer

BACKGROUND

LACTB was recently identified as a mitochondrial tumour suppressor that negatively affects cancer cell proliferation by inducing cell death and/or differentiation, depending on the cell type and tissue. However, the detailed mechanism underlying the LACTB-induced cancer cell death is largely unknown.

METHODS

We used cell-based, either in 2D or 3D conditions, and in vivo experiments to understand the LACTB mechanisms. In this regard, protein array followed by an enrichment analysis, cell proliferation assays using different compounds, western blot analysis, flow cytometry and immunofluorescence were performed. Differences between quantitative variables following normal distribution were valuated using Student t test for paired or no-paired samples according to the experiment. For in vivo experiments differences in tumour growth were analyzed by 2-way ANOVA.

RESULTS

We show, that LACTB expression leads to cell cycle arrest in G1 phase and increase of DNA oxidation that leads to activation of intrinsic caspase-independent cell death pathway. This is achieved by an increase of mitochondrial reactive oxygen species since early time points of LACTB induction.

CONCLUSION

Our work provides a deeper mechanistic insight into LACTB-mediated cancer-cell death and shows the dynamics of the cellular responses a particular tumor suppressive stimulus might evoke under different genetic landscapes.

A new means of energy supply driven by terahertz photons recovers related neural activity

Continuous and efficient energy capture represents a long-sought dream of mankind. The brain is a major energy-consuming organ; an adult brain accounts for about 2% of the body weight but consumes about 20% of the body's energy. However, it is still unclear how the brain achieves efficient use of energy. Here, using nerve cells as test subjects, we found that THz photons with a specific frequency can effectively restore the reduced frequency of action potentials caused by inadequate ATP supply, which has been demonstrated as a novel mode of energy supply, present photons emission at a particular frequency from the breaking of the ATP phosphate bond. This energy supply mechanism may play a key biophysical basis for explaining how the body efficiently obtains energy, because the quantized chemical reactions could have a high energy efficiency and ultrahigh selectivity compared with the traditional thermochemistry and photochemistry.

Oxidative stress and related metabolic alterations are induced in ex situ perfusion of donated hearts regardless of the ventricular load or leukocyte depletion

We sought to determine the role of donor blood circulating leukocytes in mediating oxidative stress and inflammation during normothermic ex situ heart perfusion (ESHP). Normothermic ESHP allows preservation of donated heart in a perfused, dynamic state, preventing ischemia. However, the cardiac function declines during ESHP, limiting the potential of this method for improvement of the outcomes of transplantation and expanding the donor pool. Extracorporeal circulation-related oxidative stress plays a critical role in the functional decline of the donor heart. Hearts from domestic pigs were perfused in working mode (WM, whole blood-based or leukocyte-depleted blood-based perfusate) or nonworking mode. Markers of oxidative stress and responsive glucose anabolic pathways were induced in the myocardium regardless of left ventricular load. Myocardial function during ESHP as well as cardioprotective mechanisms were preserved better in WM. Leukocyte-depleted perfusate did not attenuate tissue oxidative stress or perfusate proinflammatory cytokines and did not improve functional preservation. Although ESHP is associated with ongoing oxidative stress and metabolic alteration in the myocardium, preserved cardioprotective mechanisms in WM may exert beneficial effects. Leukocyte depletion of the perfusate may not attenuate inflammation and oxidative stress effectively or improve the functional preservation of the heart during ESHP.

Ferroptosis: roles and molecular mechanisms in diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a serious complication of type 1 and type 2 diabetes, which leads to the aggravation of myocardial fibrosis, disorders involving systolic and diastolic functions, and increased mortality of patients with diabetes through mechanisms such as glycolipid toxicity, inflammatory response, and oxidative stress. Ferroptosis is a form of iron-dependent regulatory cell death that is attributed to the accumulation of lipid peroxides and an imbalance in redox regulation. Increased production of lipid reactive oxygen species (ROS) during ferroptosis promotes oxidative stress and damages myocardial cells, leading to myocardial systolic and diastolic dysfunction. Overproduction of ROS is an important bridge between ferroptosis and DCM, and ferroptosis inhibitors may provide new targets for the treatment of patients with DCM.

Sodium-glucose Cotransporter 2 Inhibitors and Pathological Myocardial Hypertrophy

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a new type of oral hypoglycemic drugs that exert a hypoglycemic effect by blocking the reabsorption of glucose in the proximal renal tubules, thus promoting the excretion of glucose from urine. Their hypoglycemic effect is not dependent on insulin. Increasing data shows that SGLT2 inhibitors improve cardiovascular outcomes in patients with type 2 diabetes. Previous studies have demonstrated that SGLT2 inhibitors can reduce pathological myocardial hypertrophy with or without diabetes, but the exact mechanism remains to be elucidated. To clarify the relationship between SGLT2 inhibitors and pathological myocardial hypertrophy, with a view to providing a reference for the future treatment thereof, this study reviewed the possible mechanisms of SGLT2 inhibitors in attenuating pathological myocardial hypertrophy. We focused specifically on the mechanisms in terms of inflammation, oxidative stress, myocardial fibrosis, mitochondrial function, epicardial lipids, endothelial function, insulin resistance, cardiac hydrogen and sodium exchange, and autophagy.

Mechanisms of SGLT2 Inhibitors in Heart Failure and Their Clinical Value

ABSTRACT

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are widely used to treat diabetes mellitus. Abundant evidence has shown that SGLT2 inhibitors can reduce hospitalization for heart failure (HF) in patients with or without diabetes. An increasing number of studies are being conducted on the mechanisms of action of SGLT2 inhibitors in HF. Our review summarizes a series of clinical trials on the cardioprotective effects of SGLT2 inhibitors in the treatment of HF. We have summarized several classical SGLT2 inhibitors in cardioprotection research, including empagliflozin, dapagliflozin, canagliflozin, ertugliflozin, and sotagliflozin. In addition, we provided a brief overview of the safety and benefits of SGLT2 inhibitors. Finally, we focused on the mechanisms of SGLT2 inhibitors in the treatment of HF, including ion-exchange regulation, volume regulation, ventricular remodeling, and cardiac energy metabolism. Exploring the mechanisms of SGLT2 inhibitors has provided insight into repurposing these diabetic drugs for the treatment of HF.

Mitochondrial Permeability Transition in Stem Cells, Development, and Disease

The mitochondrial permeability transition (mPT) is a process that permits rapid exchange of small molecules across the inner mitochondrial membrane (IMM) and thus plays a vital role in mitochondrial function and cellular signaling. Formation of the pore that mediates this flux is well-documented in injury and disease but its regulation has also emerged as critical to the fate of stem cells during embryonic development. The precise molecular composition of the mPTP has been enigmatic, with far more genetic studies eliminating molecular candidates than confirming them. Rigorous studies in the recent decade have implicated central involvement of the F₁F_o ATP synthase, or complex V of the electron transport chain, and continue to confirm a regulatory role for Cyclophilin D (CypD), encoded by Ppif, in modulating the sensitivity of the pore to opening. A host of endogenous molecules have been shown to trigger flux characteristic of mPT, including positive regulators such as calcium ions, reactive oxygen species, inorganic phosphate, and fatty acids. Conductance of the pore has been described as low or high, and reversibility of pore opening appears to correspond with the relative abundance of negative regulators of mPT such as adenine nucleotides, hydrogen ion, and divalent cations that compete for calcium-binding sites in the mPTP. Current models suggest that distinct pores could be responsible for differing reversibility and conductance depending upon cellular context. Indeed, irreversible propagation of mPT inevitably leads to collapse of transmembrane potential, arrest of ATP synthesis, mitochondrial swelling, and cell death. Future studies should clarify ambiguities in mPTP structure and reveal new roles for mPT in dictating specialized cellular functions beyond cell survival that are tied to mitochondrial fitness including stem cell self-renewal and fate. The focus of this review is to describe contemporary models of the mPTP and highlight how pore activity impacts stem cells and development.

Energy metabolism disturbance in migraine: From a mitochondrial point of view

Migraine is a serious central nervous system disease with a high incidence rate. Its pathogenesis is very complex, which brings great difficulties for clinical treatment. Recently, many studies have revealed that mitochondrial dysfunction may play a key role in migraine, which affects the hyperosmotic of Ca²⁺, the excessive production of free radicals, the decrease of mitochondrial membrane potential, the imbalance of mPTP opening and closing, and the decrease of oxidative phosphorylation level, which leads to neuronal energy exhaustion and apoptosis, and finally lessens the pain threshold and migraine attack. This article mainly introduces cortical spreading depression, a pathogenesis of migraine, and then damages the related function of mitochondria, which leads to migraine. Oxidative phosphorylation and the tricarboxylic acid cycle are the main ways to provide energy for the body. 95 percent of the energy needed for cell survival is provided by the mitochondrial respiratory chain. At the same time, hypoxia can lead to cell death and migraine. The pathological opening of the mitochondrial permeability transition pore can promote the interaction between pro-apoptotic protein and mitochondrial, destroy the structure of mPTP, and further lead to cell death. The increase of mPTP permeability can promote the accumulation of reactive oxygen species, which leads to a series of changes in the expression of proteins related to energy metabolism. Both Nitric oxide and Calcitonin gene-related peptide are closely related to the attack of migraine. Recent studies have shown that changes in their contents can also affect the energy metabolism of the body, so this paper reviews the above mechanisms and discusses the mechanism of brain energy metabolism of migraine, to provide new strategies for the prevention and treatment of migraine and promote the development of individualized and accurate treatment of migraine.

TRPC Channels in the Physiology and Pathophysiology of the Renal Tubular System: What Do We Know?

The study of transient receptor potential (TRP) channels has dramatically increased during the past few years. TRP channels function as sensors and effectors in the cellular adaptation to environmental changes. Here, we review literature investigating the physiological and pathophysiological roles of TRPC channels in the renal tubular system with a focus on TRPC3 and TRPC6. TRPC3 plays a key role in Ca²⁺ homeostasis and is involved in transcellular Ca²⁺ reabsorption in the proximal tubule and the collecting duct. TRPC3 also conveys the osmosensitivity of principal cells of the collecting duct and is implicated in vasopressin-induced membrane translocation of AQP-2. Autosomal dominant polycystic kidney disease (ADPKD) can often be attributed to mutations of the PKD2 gene. TRPC3 is supposed to have a detrimental role in ADPKD-like conditions. The tubule-specific physiological functions of TRPC6 have not yet been entirely elucidated. Its pathophysiological role in ischemia-reperfusion injuries is a subject of debate. However, TRPC6 seems to be involved in tumorigenesis of renal cell carcinoma. In summary, TRPC channels are relevant in multiples conditions of the renal tubular system. There is a need to further elucidate their pathophysiology to better understand certain renal disorders and ultimately create new therapeutic targets to improve patient care.

The Therapeutic Strategies Targeting Mitochondrial Metabolism in Cardiovascular Disease

Cardiovascular disease (CVD) is a group of systemic disorders threatening human health with complex pathogenesis, among which mitochondrial energy metabolism reprogramming has a critical role. Mitochondria are cell organelles that fuel the energy essential for biochemical reactions and maintain normal physiological functions of the body. Mitochondrial metabolic disorders are extensively involved in the progression of CVD, especially for energy-demanding organs such as the heart. Therefore, elucidating the role of mitochondrial metabolism in the progression of CVD is of great significance to further understand the pathogenesis of CVD and explore preventive and therapeutic methods. In this review, we discuss the major factors of mitochondrial metabolism and their potential roles in the prevention and treatment of CVD. The current application of mitochondria-targeted therapeutic agents in the treatment of CVD and advances in mitochondria-targeted gene therapy technologies are also overviewed.

Zn2+ protect cardiac H9c2 cells from endoplasmic reticulum stress by preventing mPTP opening through MCU

Zn2+ regulates endoplasmic reticulum stress (ERS) and is essential for myocardial protection through gating the mitochondrial permeability transition pore (mPTP). However, the underlining mechanism of the mPTP opening remains uncertain. Cells under sustained ERS induce unfolded protein responses (UPR) and cell apoptosis. Glucose regulatory protein 78 (GRP 78) and glucose regulatory protein 94 (GRP 94) are marker proteins of ERS and regulate the onset of apoptosis through the endoplasmic reticulum signaling pathway. We found tunicamycin (TM) treatment activates ERS and significantly increases intracellular Ca2+ and mitochondrial reactive oxygen species (ROS) levels in H9c2 cardiomyocyte cells. Zn2+ markedly decreased protein level of GRP 78/94 and suppressed intracellular Ca2+ and ROS elevation. Mitochondrial calcium uniporter (MCU) is an important Ca2+ transporter protein, through which Zn2+ enter mitochondria. MCU inhibitor ruthenium red (RR) or siRNA significantly reversed the Zinc effect on GRP 78, mitochondrial Ca2+ and ROS. Additionally, Zn2+ prevented TM-induced mPTP opening and decreased mitochondrial Ca2+ concentration, which were blocked through inhibiting or knockdown MCU with siRNA. In summary, our study suggests that Zn2+ protected cardiac ERS by elevating Ca2+ and closing mPTP through MCU.

Interconnection between cardiovascular, renal and metabolic disorders: A narrative review with a focus on Japan

Insights from epidemiological, clinical and basic research are illuminating the interplay between metabolic disorders, cardiovascular disease (CVD) and kidney dysfunction, termed cardio-renal-metabolic (CRM) disease. Broadly defined, CRM disease involves multidirectional interactions between metabolic diseases such as type 2 diabetes (T2D), various types of CVD and chronic kidney disease (CKD). T2D confers increased risk for heart failure, which-although well known-has only recently come into focus for treatment, and may differ by ethnicity, whereas atherosclerotic heart disease is a well-established complication of T2D. Many people with T2D also have CKD, with a higher risk in Asians than their Western counterparts. Furthermore, CVD increases the risk of CKD and vice versa, with heart failure, notably, present in approximately half of CKD patients. Molecular mechanisms involved in CRM disease include hyperglycaemia, insulin resistance, hyperactivity of the renin-angiotensin-aldosterone system, production of advanced glycation end-products, oxidative stress, lipotoxicity, endoplasmic reticulum stress, calcium-handling abnormalities, mitochondrial malfunction and deficient energy production, and chronic inflammation. Pathophysiological manifestations of these processes include diabetic cardiomyopathy, vascular endothelial dysfunction, cardiac and renal fibrosis, glomerular hyperfiltration, renal hypoperfusion and venous congestion, reduced exercise tolerance leading to metabolic dysfunction, and calcification of atherosclerotic plaque. Importantly, recognition of the interaction between CRM diseases would enable a more holistic approach to CRM care, rather than isolated treatment of individual conditions, which may improve patient outcomes. Finally, aspects of CRM diseases may differ between Western and East Asian countries such as Japan, a super-ageing country, with potential differences in epidemiology, complications and prognosis that represent an important avenue for future research.

Damage-associated molecular patterns in vitiligo: igniter fuse from oxidative stress to melanocyte loss

OBJECTIVES

The pathogenesis of vitiligo remains unclear. In this review, we comprehensively describe the role of damage associated molecular patterns (DAMPs) during vitiligo pathogenesis.

METHODS

Published papers on vitiligo, oxidative stress and DAMPs were collected and reviewed via database searching on PubMed, MEDLINE and Embase, etc.

RESULTS

Oxidative stress may be an important inducer of vitiligo. At high oxidative stress levels, damage-associated molecular patterns (DAMPs) are released from keratinocytes or melanocytes in the skin and induce downstream immune responses during vitiligo. Treatment regimens targeting DAMPs can effectively improve disease severity.

DISCUSSION

DAMPs play key roles in initiating host defenses against danger signals, deteriorating the condition of vitiligo. DAMP levels in serum and skin may be used as biomarkers to indicate vitiligo activity and prognosis. Targeted therapies, incorporating HMGB1, Hsp70, and IL-15 could significantly improve disease etiology. Thus, novel strategies could be identified for vitiligo treatment by targeting DAMPs.