Mitochondrial Function, Biology, and Role in Disease: A Scientific Statement From the American Heart Association

Measurement of Mitochondrial ROS Formation

Reactive oxygen species (ROS) play important roles in physiological and pathological processes. Mitochondria, particularly in skeletal and cardiac myocytes, are recognized as the primary site of ROS generation. Detecting oxidative modifications of intracellular or circulating molecules, such as lipids, proteins, and nucleic acids, is commonly employed to indicate ROS formation. However, this approach is indirect and provides limited insights into the spatiotemporal aspects of ROS generation. Understanding these aspects is crucial for comprehending the role of ROS in various pathophysiological conditions. To address this, fluorescent probes can be employed to measure ROS formation, offering a means to investigate ROS generation in both isolated mitochondria and intact cells. This chapter outlines three prominent examples for the use of fluorescent sensors to evaluate mitochondrial ROS formation in either isolated organelles or intact cells. The methods are explained in detail, and an analysis of the limitations of each technique is provided, underscoring potential sources of errors during the assay and the subsequent interpretation of results.

Application of hydrogen sulfide donor conjugates in different diseases

As an endogenous gas signaling molecule, hydrogen sulfide (H2S) has been proved to have a variety of biological activities. Studies have shown that in some disease state H2S concentration in the body is lower than normal state. Based on these findings, exogenous H2S supplementation is expected to be an effective treatment for many diseases. In recent years, a lot of H2S-releasing substances, namely H2S donors, have emerged as H2S sources. Specifically, various H2S donors also could be connected to drugs or compounds to form H2S donor conjugates. Many studies have found that H2S donor conjugates can not only retain the activity of the parent drug, but also reduce the adverse effects of the parent drug, this makes H2S donor conjugates to be a new kind of drug candidates. In this article, H2S donor conjugates will be reviewed and classified according to different diseases, such as inflammation, cardiovascular and cerebrovascular diseases, diseases of central nervous system and cancer. This review aims to provide an idea for researchers for further study of H2S and H2S donor conjugates.

The multifaceted role of macrophage mitophagy in SiO2-induced pulmonary fibrosis: A brief review

Prolonged exposure to environments with high concentrations of crystalline silica (CS) can lead to silicosis. Macrophages play a crucial role in the pathogenesis of silicosis. In the process of silicosis, silica (SiO2) invades alveolar macrophages (AMs) and induces mitophagy which usually exists in three states: normal, excessive, and/or deficiency. Different mitophagy states lead to corresponding toxic responses, including successful macrophage repair, injury, necrosis, apoptosis, and even pulmonary fibrosis. This is a complex process accompanied by various cytokines. Unfortunately, the details have not been fully systematically summarized. Therefore, it is necessary to elucidate the role of macrophage mitophagy in SiO2-induced pulmonary fibrosis by systematic analysis on the literature reports. In this review, we first summarized the current data on the macrophage mitophagy in the development of SiO2-induced pulmonary fibrosis. Then, we introduce the molecular mechanism on how SiO2-induced mitophagy causes pulmonary fibrosis. Finally, we focus on introducing new therapies based on newly developed mitophagy-inducing strategies. We conclude that macrophage mitophagy plays a multifaceted role in the progression of SiO2-induced pulmonary fibrosis, and reprogramming the macrophage mitophagy state accordingly may be a potential means of preventing and treating pulmonary fibrosis.

Heart Failure: A Deficiency of Energy-A Path Yet to Discover and Walk

Heart failure is a complex syndrome and our understanding and therapeutic approach relies mostly on its phenotypic presentation. Notably, the heart is characterized as the most energy-consuming organ, being both a producer and consumer, in order to satisfy multiple cardiac functions: ion exchange, electromechanical coordination, excitation-contraction coupling, etc. By obtaining further knowledge of the cardiac energy field, we can probably better characterize the basic pathophysiological events occurring in heart disease patients and understand the metabolic substance changes, the relationship between the alteration of energy production/consumption, and hence energetic deficiency not only in the heart as a whole but in every single cardiac territory, which will hopefully provide us with the opportunity to uncover the beginning of the heart failure process. In this respect, using (a) newer imaging techniques, (b) biomedicine, (c) nanotechnology, and (d) artificial intelligence, we can gain a deeper understanding of this complex syndrome. This, in turn, can lead to earlier and more effective therapeutic approaches, ultimately improving human health. To date, the scientific community has not given sufficient attention to the energetic starvation model. In our view, this review aims to encourage scientists and the medical community to conduct studies for a better understanding and treatment of this syndrome.

Role of reactive oxygen species in regulating epigenetic modifications

Reactive oxygen species (ROS) originate from diverse sources and regulate multiple signaling pathways within the cellular environment. Their generation is intricately controlled, and disruptions in their signaling or atypical levels can precipitate pathological conditions. Epigenetics, the examination of heritable alterations in gene expression independent of changes in the genetic code, has been implicated in the pathogenesis of various diseases through aberrant epigenetic modifications. The significant contribution of epigenetic modifications to disease progression underscores their potential as crucial therapeutic targets for a wide array of medical conditions. This study begins by providing an overview of ROS and epigenetics, followed by a discussion on the mechanisms of epigenetic modifications such as DNA methylation, histone modification, and RNA modification-mediated regulation. Subsequently, a detailed examination of the interaction between ROS and epigenetic modifications is presented, offering new perspectives and avenues for exploring the mechanisms underlying specific epigenetic diseases and the development of novel therapeutics.

Mitochondrial respiratory pathways in immature rat heart tissue using different cardioplegic solutions

INTRODUCTION

Minor defects in the mitochondrial ATP-generating system and post-cardioplegia oxidative phosphorylation can negatively impact cardiac function in immature hearts. This study aimed to examine the mitochondrial respiratory pathway using three different cardioplegic solutions (Custodiol HTK, St. Thomas, and Del Nido) during moderate (1 h) and long (3 h) ischemic periods.

METHODS

A total of 41 male Wistar albino rats were utilized in this study. Five experiments were conducted without the use of any cardioplegic solution (CP0 group). To assess both moderate and prolonged ischemic periods, six experiments were carried out in each of the following groups: CP1 group (St. Thomas solution), CP2 group (Custodiol HTK solution), and CP3 group (Del Nido solution).

RESULTS

After 1 h, the highest mitochondrial respiration rate was observed in the CP3 group and the lowest in the CP1 group (p = 0.006). After adding ADP substrate, the highest mitochondrial ATP-production-coupled respiration was recorded in the CP3 group, which was similar to the control group CP0. After 3 h, while evaluating the ratio between mitochondrial respiration ATP-production coupled and basal respiration, significant differences were found between CP1 group and CP3 group (p = 0.035), as well as between the CP1 and CP0 groups (p = 0.045). Additionally, by assessing the condition of the outer mitochondrial membrane using the Cyt C effect (Cyt/Phos [ADP]), significant differences were observed between the CP1 and CP3 group (p = 0.004), as well as between CP1 and CP0 groups (p = 0.003).

CONCLUSION

Del Nido cardioplegic solution provided optimal mitochondrial protection under moderate and long myocardial ischemia conditions.

Mandatory role of endoplasmic reticulum and its pentose phosphate shunt in the myocardial defense mechanisms against the redox stress induced by anthracyclines

Anthracyclines' cardiotoxicity involves an accelerated generation of reactive oxygen species. This oxidative damage has been found to accelerate the expression of hexose-6P-dehydrogenase (H6PD), that channels glucose-6-phosphate (G6P) through the pentose phosphate pathway (PPP) confined within the endoplasmic/sarcoplasmic reticulum (SR). To verify the role of SR-PPP in the defense mechanisms activated by doxorubicin (DXR) in cardiomyocytes, we tested the effect of this drug in H6PD knockout mice (H6PD-/-). Twenty-eight wildtype (WT) and 32 H6PD-/- mice were divided into four groups to be treated with intraperitoneal administration of saline (untreated) or DXR (8 mg/Kg once a week for 3 weeks). One week thereafter, survivors underwent imaging of 18F-deoxyglucose (FDG) uptake and were sacrificed to evaluate the levels of H6PD, glucose-6P-dehydrogenase (G6PD), G6P transporter (G6PT), and malondialdehyde. The mRNA levels of SR Ca2+-ATPase 2 (Serca2) and ryanodine receptors 2 (RyR2) were evaluated and complemented with Hematoxylin/Eosin staining and transmission electron microscopy. During the treatment period, 1/14 DXR-WT and 12/18 DXR-H6PD-/- died. At microPET, DXR-H6PD-/- survivors displayed an increase in left ventricular size (p < 0.001) coupled with a decreased urinary output, suggesting a severe hemodynamic impairment. At ex vivo analysis, H6PD-/- condition was associated with an oxidative damage independent of treatment type. DXR increased H6PD expression only in WT mice, while G6PT abundance increased in both groups, mismatching a generalized decrease of G6PD levels. Switching-off SR-PPP impaired reticular accumulation of Ca2+ decelerating Serca2 expression and upregulating RyR2 mRNA level. It thus altered mitochondrial ultrastructure eventually resulting in a cardiomyocyte loss. The recognized vulnerability of SR to the anthracycline oxidative damage is counterbalanced by an acceleration of G6P flux through a PPP confined within the reticular lumen. The interplay of SR-PPP with the intracellular Ca2+ exchanges regulators in cardiomyocytes configure the reticular PPP as a potential new target for strategies aimed to decrease anthracycline toxicity.

Endogenous complement 1q binding protein (C1qbp) regulates mitochondrial permeability transition and post-myocardial infarction remodeling and dysfunction

The mitochondrial permeability transition (MPT) pore regulates necrotic cell death following diverse cardiac insults. While the componentry of the pore itself remains controversial, Cyclophilin D (CypD) has been well-established as a positive regulator of pore opening. We have previously identified Complement 1q-binding protein (C1qbp) as a novel CypD-interacting molecule and a negative regulator of MPT-dependent cell death in vitro. However, its effects on the MPT pore and sensitivity to cell death in the heart remain untested. We therefore hypothesized that C1qbp would inhibit MPT in cardiac mitochondria and protect cardiac myocytes against cell death in vivo. To investigate the effects of C1qbp in the myocardium we generated gain- and loss-of-function mice. Transgenic C1qbp overexpression resulted in decreased complex protein expression and reduced mitochondrial respiration and ATP production but MPT was unaffected. In contrast, while C1qbp+/- mice did not exhibit any changes in mitochondrial protein expression, respiration, or ATP, the MPT pore was markedly sensitized to Ca2+ in these animals. Neither overexpression nor depletion of C1qbp significantly affected baseline heart morphology or function at 3 months of age. When subjected to myocardial infarction, C1qbp transgenic mice exhibited similar infarct sizes and cardiac remodeling to non-transgenic mice, consistent with the lack of an effect on MPT. In contrast, cardiac scar formation and dysfunction were significantly increased in the C1qbp+/- mice compared to C1qbp+/+ controls. Our results suggest that C1qbp is required for normal regulation of the MPT pore and mitochondrial function, and influences cardiac remodeling following MI, the latter more likely being independent of C1qbp effects on the MPT pore.

Gene therapy for atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia in adults. Current limitations of pharmacological and ablative therapies motivate the development of novel therapies as next generation treatments for AF. The arrhythmia mechanisms creating and sustaining AF are key elements in the development of this novel treatment. Gene therapy provides a useful platform that allows us to regulate the mechanisms of interest using a suitable transgene(s), vector, and delivery method. Effective gene therapy strategies in the literature have targeted maladaptive electrical or structural remodeling that increase vulnerability to AF. In this review, we will summarize key elements of gene therapy for AF, including molecular targets, gene transfer vectors, atrial gene delivery and preclinical efficacy and toxicity testing. Recent advances and challenges in the field will be also discussed.

Mitochondrial Reactive Oxygen Species Dysregulation in Heart Failure with Preserved Ejection Fraction: A Fraction of the Whole

Heart failure with preserved ejection fraction (HFpEF) is a multifarious syndrome, accounting for over half of heart failure (HF) patients receiving clinical treatment. The prevalence of HFpEF is rapidly increasing in the coming decades as the global population ages. It is becoming clearer that HFpEF has a lot of different causes, which makes it challenging to find effective treatments. Currently, there are no proven treatments for people with deteriorating HF or HFpEF. Although the pathophysiologic foundations of HFpEF are complex, excessive reactive oxygen species (ROS) generation and increased oxidative stress caused by mitochondrial dysfunction seem to play a critical role in the pathogenesis of HFpEF. Emerging evidence from animal models and human myocardial tissues from failed hearts shows that mitochondrial aberrations cause a marked increase in mitochondrial ROS (mtROS) production and oxidative stress. Furthermore, studies have reported that common HF medications like beta blockers, angiotensin receptor blockers, angiotensin-converting enzyme inhibitors, and mineralocorticoid receptor antagonists indirectly reduce the production of mtROS. Despite the harmful effects of ROS on cardiac remodeling, maintaining mitochondrial homeostasis and cardiac functions requires small amounts of ROS. In this review, we will provide an overview and discussion of the recent findings on mtROS production, its threshold for imbalance, and the subsequent dysfunction that leads to related cardiac and systemic phenotypes in the context of HFpEF. We will also focus on newly discovered cellular and molecular mechanisms underlying ROS dysregulation, current therapeutic options, and future perspectives for treating HFpEF by targeting mtROS and the associated signal molecules.

Calcium signaling in mitochondrial intermembrane space

The mitochondrial intermembrane space (IMS) is a highly protected compartment, second only to the matrix. It is a crucial bridge, coordinating mitochondrial activities with cellular processes such as metabolites, protein, lipid, and ion exchange. This regulation influences signaling pathways for metabolic activities and cellular homeostasis. The IMS harbors various proteins critical for initiating apoptotic cascades and regulating reactive oxygen species production by controlling the respiratory chain. Calcium (Ca2+), a key intracellular secondary messenger, enter the mitochondrial matrix via the IMS, regulating mitochondrial bioenergetics, ATP production, modulating cell death pathways. IMS acts as a regulatory site for Ca2+ entry due to the presence of different Ca2+ sensors such as MICUs, solute carriers (SLCs); ion exchangers (LETM1/SCaMCs); S100A1, mitochondrial glycerol-3-phosphate dehydrogenase, and EFHD1, each with unique Ca2+ binding motifs and spatial localizations. This review primarily emphasizes the role of these IMS-localized Ca2+ sensors concerning their spatial localization, mechanism, and molecular functions. Additionally, we discuss how these sensors contribute to the progression and pathogenesis of various human health conditions and diseases.

Pharmacological Inhibition of Phosphoglycerate Kinase 1 Reduces OxiDative Stress and Restores Impaired Autophagy in Experimental Acute Pancreatitis

Damage to pancreatic acinar cells (PAC) and intracellular metabolic disturbances play crucial roles in pancreatic necrosis during acute pancreatitis (AP). Phosphoglycerate kinase 1 (PGK1) is a crucial catalytic enzyme in glycolysis. However, the impact of PGK1-involving glycolysis in regulating metabolic necrosis in AP is unclear. Transcriptome analysis of pancreatic tissues revealed significant changes in the glycolysis pathway and PGK1 which positively correlated with the inflammatory response and oxidative stress injury in AP mice. Furthermore, we observed a substantial increase in PGK1 expression in damaged PAC, positively correlating with PAC necrosis. Treatment with NG52, a specific PGK1 inhibitor, ameliorated pancreatic necrosis, inflammatory damage, and oxidative stress. Transcriptomic data before and after NG52 treatment along with the Programmed Cell Death database confirmed that NG52 protected against PAC damage by rescuing impaired autophagy in AP. Additionally, the protective effect of NG52 was validated following pancreatic duct ligation. These findings underscore the involvement of PGK1 in AP pathogenesis, highlighting that PGK1 inhibition can mitigate AP-induced pancreatic necrosis, attenuate inflammatory and oxidative stress injury, and rescue impaired autophagy. Thus, the study findings suggest a promising interventional target for pancreatic necrosis, offering novel strategies for therapeutic approaches to clinical AP.

Advancements in mitochondrial-targeted nanotherapeutics: overcoming biological obstacles and optimizing drug delivery

In recent decades, nanotechnology has significantly advanced drug delivery systems, particularly in targeting subcellular organelles, thus opening new avenues for disease treatment. Mitochondria, critical for cellular energy and health, when dysfunctional, contribute to cancer, neurodegenerative diseases, and metabolic disorders. This has propelled the development of nanomedicines aimed at precise mitochondrial targeting to modulate their function, marking a research hotspot. This review delves into the recent advancements in mitochondrial-targeted nanotherapeutics, with a comprehensive focus on targeting strategies, nanocarrier designs, and their therapeutic applications. It emphasizes nanotechnology's role in enhancing drug delivery by overcoming biological barriers and optimizing drug design for specific mitochondrial targeting. Strategies exploiting mitochondrial membrane potential differences and specific targeting ligands improve the delivery and mitochondrial accumulation of nanomedicines. The use of diverse nanocarriers, including liposomes, polymer nanoparticles, and inorganic nanoparticles, tailored for effective mitochondrial targeting, shows promise in anti-tumor and neurodegenerative treatments. The review addresses the challenges and future directions in mitochondrial targeting nanotherapy, highlighting the need for precision, reduced toxicity, and clinical validation. Mitochondrial targeting nanotherapy stands at the forefront of therapeutic strategies, offering innovative treatment perspectives. Ongoing innovation and research are crucial for developing more precise and effective treatment modalities.

Mitochondrial Dysfunction as a Potential Mechanism Mediating Cardiac Comorbidities in Parkinson's Disease

Individuals diagnosed with Parkinson's disease (PD) often exhibit heightened susceptibility to cardiac dysfunction, reflecting a complex interaction between these conditions. The involvement of mitochondrial dysfunction in the development and progression of cardiac dysfunction and PD suggests a plausible commonality in some aspects of their molecular pathogenesis, potentially contributing to the prevalence of cardiac issues in PD. Mitochondria, crucial organelles responsible for energy production and cellular regulation, play important roles in tissues with high energetic demands, such as neurons and cardiac cells. Mitochondrial dysfunction can occur in different and non-mutually exclusive ways; however, some mechanisms include alterations in mitochondrial dynamics, compromised bioenergetics, biogenesis deficits, oxidative stress, impaired mitophagy, and disrupted calcium balance. It is plausible that these factors contribute to the increased prevalence of cardiac dysfunction in PD, suggesting mitochondrial health as a potential target for therapeutic intervention. This review provides an overview of the physiological mechanisms underlying mitochondrial quality control systems. It summarises the diverse roles of mitochondria in brain and heart function, highlighting shared pathways potentially exhibiting dysfunction and driving cardiac comorbidities in PD. By highlighting strategies to mitigate dysfunction associated with mitochondrial impairment in cardiac and neural tissues, our review aims to provide new perspectives on therapeutic approaches.

Mitochondrial abnormalities in septic cardiomyopathy

Septic cardiomyopathy is a common complication in patients with sepsis, and is one of the indicators of poor prognosis. Its pathogenesis is complex, involving calcium ion imbalance in cardiomyocytes, nitric oxide (NO) synthesis disorder, mitochondrial abnormalities and immune inflammatory reaction, especially mitochondrial abnormalities. In this paper, the mechanism of mitochondrial abnormalities causing septic cardiomyopathy was discussed from the aspects of mitochondrial structure change, mitochondrial energy metabolism disorder, redox imbalance, mitochondrial calcium overload, mitochondrial biosynthesis and autophagy abnormalities.

Overview of mechanism of electroacupuncture pretreatment for prevention and treatment of cardiovascular and cerebrovascular diseases

Cardio-cerebrovascular disease (CCVD) is a serious threat to huma strategy to prevent the occurrence and development of disease by giving electroacupuncture intervention before the disease occurs. EAP has been shown in many preclinical studies to relieve ischemic symptoms and improve damage from ischemia-reperfusion, with no comprehensive review of its mechanisms in cardiovascular disease yet. In this paper, we first systematically discussed the meridian and acupoint selection law of EAP for CCVD and focused on the progress of the mechanism of action of EAP for the prevention and treatment of CCVD. As a result, in preclinical studies, AMI and MCAO models are commonly used to simulate ischemic injury in CCVD, while MIRI and CI/RI models are used to simulate reperfusion injury caused by blood flow recovery after focal tissue ischemia. According to the meridian matching rules of EAP for CCVD, PC6 in the pericardial meridian is the most commonly used acupoint in cardiovascular diseases, while GV20 in the Du meridian is the most commonly used acupoint in cerebrovascular diseases. In terms of intervention parameters, EAP intervention generally lasts for 30 min, with acupuncture depths mostly between 1.5 and 5 mm, stimulation intensities mostly at 1 mA, and commonly used frequencies being low frequencies. In terms of molecular mechanisms, the key pathways of EAP in preventing and treating cardiovascular and cerebrovascular diseases are partially similar. EAP can play a protective role in cardiovascular and cerebrovascular diseases by promoting autophagy, regulating Ca2+ overload, and promoting vascular regeneration through anti-inflammatory reactions, antioxidant stress, and anti-apoptosis. Of course, both pathways involved have their corresponding specificities. When using EAP to prevent and treat cardiovascular diseases, it involves the metabolic pathway of glutamate, while when using EAP to prevent and treat cerebrovascular diseases, it involves the homeostasis of the blood-brain barrier and the release of neurotransmitters and nutritional factors. I hope these data can provide experimental basis and reference for the clinical promotion and application of EAP in CCVD treatment.

Aging-associated atrial fibrillation: A comprehensive review focusing on the potential mechanisms

Atrial fibrillation (AF) has been receiving a lot of attention from scientists and clinicians because it is an extremely common clinical condition. Due to its special hemodynamic changes, AF has a high rate of disability and mortality. So far, although AF has some therapeutic means, it is still an incurable disease because of its complex risk factors and pathophysiologic mechanisms, which is a difficult problem for global public health. Age is an important independent risk factor for AF, and the incidence of AF increases with age. To date, there is no comprehensive review on aging-associated AF. In this review, we systematically discuss the pathophysiologic evidence for aging-associated AF, and in particular explore the pathophysiologic mechanisms of mitochondrial dysfunction, telomere attrition, cellular senescence, disabled macroautophagy, and gut dysbiosis involved in recent studies with aging-associated AF. We hope that by exploring the various dimensions of aging-associated AF, we can better understand the specific relationship between age and AF, which may be crucial for innovative treatments of aging-associated AF.

Pleiotropic Effects of Peroxisome Proliferator-Activated Receptor Alpha and Gamma Agonists on Myocardial Damage: Molecular Mechanisms and Clinical Evidence-A Narrative Review

Cardiovascular diseases remain the leading cause of death in the world, and that is why finding an effective and multi-functional treatment alternative to combat these diseases has become more important. Fibrates and thiazolidinediones, peroxisome proliferator-activated receptors alpha and gamma are the pharmacological therapies used to treat dyslipidemia and type 2 diabetes, respectively. New mechanisms of action of these drugs have been found, demonstrating their pleiotropic effects, which contribute to preserving the heart by reducing or even preventing myocardial damage. Here, we review the mechanisms underlying the cardioprotective effects of PPAR agonists and regulating morphological and physiological heart alterations (metabolic flexibility, mitochondrial damage, apoptosis, structural remodeling, and inflammation). Moreover, clinical evidence regarding the cardioprotective effect of PPAR agonists is also addressed.

Multifaceted role of dynamin-related protein 1 in cardiovascular disease: From mitochondrial fission to therapeutic interventions

Mitochondria are central to cellular energy production and metabolic regulation, particularly in cardiomyocytes. These organelles constantly undergo cycles of fusion and fission, orchestrated by key proteins like Dynamin-related Protein 1 (Drp-1). This review focuses on the intricate roles of Drp-1 in regulating mitochondrial dynamics, its implications in cardiovascular health, and particularly in myocardial infarction. Drp-1 is not merely a mediator of mitochondrial fission; it also plays pivotal roles in autophagy, mitophagy, apoptosis, and necrosis in cardiac cells. This multifaceted functionality is often modulated through various post-translational alterations, and Drp-1's interaction with intracellular calcium (Ca2 + ) adds another layer of complexity. We also explore the pathological consequences of Drp-1 dysregulation, including increased reactive oxygen species (ROS) production and endothelial dysfunction. Furthermore, this review delves into the potential therapeutic interventions targeting Drp-1 to modulate mitochondrial dynamics and improve cardiovascular outcomes. We highlight recent findings on the interaction between Drp-1 and sirtuin-3 and suggest that understanding this interaction may open new avenues for therapeutically modulating endothelial cells, fibroblasts, and cardiomyocytes. As the cardiovascular system increasingly becomes the focal point of aging and chronic disease research, understanding the nuances of Drp-1's functionality can lead to innovative therapeutic approaches.

Emerging interactions between mitochondria and NAD+ metabolism in cardiometabolic diseases

Nicotinamide adenine dinucleotide (NAD+) is an essential coenzyme for redox reactions and regulates cellular catabolic pathways. An intertwined relationship exists between NAD+ and mitochondria, with consequences for mitochondrial function. Dysregulation in NAD+ homeostasis can lead to impaired energetics and increased oxidative stress, contributing to the pathogenesis of cardiometabolic diseases. In this review, we explore how disruptions in NAD+ homeostasis impact mitochondrial function in various cardiometabolic diseases. We discuss emerging studies demonstrating that enhancing NAD+ synthesis or inhibiting its consumption can ameliorate complications of this family of pathological conditions. Additionally, we highlight the potential role and therapeutic promise of mitochondrial NAD+ transporters in regulating cellular and mitochondrial NAD+ homeostasis.

Interplay between hypoxia inducible Factor-1 and mitochondria in cardiac diseases

Ischemic heart diseases and cardiomyopathies are characterized by hypoxia, energy starvation and mitochondrial dysfunction. HIF-1 acts as a cellular oxygen sensor, tuning the balance of metabolic and oxidative stress pathways to provide ATP and sustain cell survival. Acting on mitochondria, HIF-1 regulates different processes such as energy substrate utilization, oxidative phosphorylation and mitochondrial dynamics. In turn, mitochondrial homeostasis modifications impact HIF-1 activity. This underlies that HIF-1 and mitochondria are tightly interconnected to maintain cell homeostasis. Despite many evidences linking HIF-1 and mitochondria, the mechanistic insights are far from being understood, particularly in the context of cardiac diseases. Here, we explore the current understanding of how HIF-1, reactive oxygen species and cell metabolism are interconnected, with a specific focus on mitochondrial function and dynamics. We also discuss the divergent roles of HIF in acute and chronic cardiac diseases in order to highlight that HIF-1, mitochondria and oxidative stress interaction deserves to be deeply investigated. While the strategies aiming at stabilizing HIF-1 have provided beneficial effects in acute ischemic injury, some deleterious effects were observed during prolonged HIF-1 activation. Thus, deciphering the link between HIF-1 and mitochondria will help to optimize HIF-1 modulation and provide new therapeutic perspectives for the treatment of cardiovascular pathologies.

Protein modification in neurodegenerative diseases

Posttranslational modifications play a crucial role in governing cellular functions and protein behavior. Researchers have implicated dysregulated posttranslational modifications in protein misfolding, which results in cytotoxicity, particularly in neurodegenerative diseases such as Alzheimer disease, Parkinson disease, and Huntington disease. These aberrant posttranslational modifications cause proteins to gather in certain parts of the brain that are linked to the development of the diseases. This leads to neuronal dysfunction and the start of neurodegenerative disease symptoms. Cognitive decline and neurological impairments commonly manifest in neurodegenerative disease patients, underscoring the urgency of comprehending the posttranslational modifications' impact on protein function for targeted therapeutic interventions. This review elucidates the critical link between neurodegenerative diseases and specific posttranslational modifications, focusing on Tau, APP, α-synuclein, Huntingtin protein, Parkin, DJ-1, and Drp1. By delineating the prominent aberrant posttranslational modifications within Alzheimer disease, Parkinson disease, and Huntington disease, the review underscores the significance of understanding the interplay among these modifications. Emphasizing 10 key abnormal posttranslational modifications, this study aims to provide a comprehensive framework for investigating neurodegenerative diseases holistically. The insights presented herein shed light on potential therapeutic avenues aimed at modulating posttranslational modifications to mitigate protein aggregation and retard neurodegenerative disease progression.

Associations between mitochondrial copy number, exercise capacity, physiologic cost of walking, and cardiac strain in young adult survivors of childhood cancer

PURPOSE

Childhood cancer survivors are at risk for cardiac dysfunction and impaired physical performance, though underlying cellular mechanisms are not well studied. In this cross-sectional study, we examined the association between peripheral blood mitochondrial DNA copy number (mtDNA-CN, a proxy for mitochondrial function) and markers of performance impairment and cardiac dysfunction.

METHODS

Whole-genome sequencing, validated by quantitative polymerase chain reaction, was used to estimate mtDNA-CN in 1720 adult survivors of childhood cancer (48.5% female; mean age = 30.7 years, standard deviation (SD) = 9.0). Multivariable logistic regression was performed to evaluate the associations between mtDNA-CN and exercise intolerance, walking inefficiency, and abnormal global longitudinal strain (GLS), adjusting for treatment exposures, age, sex, and race and ethnicity.

RESULTS

The prevalence of exercise intolerance, walking inefficiency, and abnormal GLS among survivors was 25.7%, 10.7%, and 31.7%, respectively. Each SD increase of mtDNA-CN was associated with decreased odds of abnormal GLS (adjusted odds ratio (OR) = 0.88, p = 0.04) but was not associated with exercise intolerance (OR = 1.02, p = 0.76) or walking inefficiency (OR = 1.06, p = 0.46). Alkylating agent exposure was associated with increased odds of exercise intolerance (OR = 2.25, p < 0.0001), walking inefficiency (OR = 2.37, p < 0.0001), and abnormal GLS (OR = 1.78, p = 0.0002).

CONCLUSIONS

Increased mtDNA-CN is associated with decreased odds of abnormal cardiac function in childhood cancer survivors.

IMPLICATIONS FOR CANCER SURVIVORS

These findings demonstrate a potential role for mtDNA-CN as a biomarker of early cardiac dysfunction in this population.

Is There a Mitochondrial Protection via Remote Ischemic Conditioning in Settings of Anticancer Therapy Cardiotoxicity?

PURPOSE OF REVIEW

To provide an overview of (a) protective effects on mitochondria induced by remote ischemic conditioning (RIC) and (b) mitochondrial damage caused by anticancer therapy. We then discuss the available results of studies on mitochondrial protection via RIC in anticancer therapy-induced cardiotoxicity.

RECENT FINDINGS

In three experimental studies in healthy mice and pigs, there was a RIC-mediated protection against anthracycline-induced cardiotoxicity and there was some evidence of improved mitochondrial function with RIC. The RIC-mediated protection was not confirmed in the two available studies in cancer patients. In adult cancer patients, RIC was associated with an adverse outcome. There are no data on mitochondrial function in cancer patients. Studies in tumor-bearing animals are needed to determine whether RIC does not interfere with the anticancer properties of the drugs and whether RIC actually improves mitochondrial function, ultimately resulting in improved cardiac function.

N6-methyldeoxyadenosine modification difference contributes to homocysteine-induced mitochondrial perturbation in rat hippocampal primary neurons and PC12 cells

Elevated homocysteine (Hcy) levels are detrimental to neuronal cells and contribute to cognitive dysfunction in rats. Mitochondria plays a crucial role in cellular energy metabolism. Interestingly, the damaging effects of Hcy in vivo and in vitro conditions exhibit distinct results. Herein, we aimed to investigate the effects of Hcy on mitochondrial function in primary neurons and PC12 cells and explore the underlying mechanisms involved. The metabolic intermediates of Hcy act as methyl donors and play important epigenetic regulatory roles. N6-methyldeoxyadenosine (6 mA) modification, which is enriched in mitochondrial DNA (mtDNA), can be mediated by methylase METTL4. Our study suggested that mitochondrial perturbation caused by Hcy in primary neurons and PC12 cells may be attributable to mtDNA 6 mA modification difference. Hcy could activate the expression of METTL4 within mitochondria to facilitate mtDNA 6 mA status, and repress mtDNA transcription, then result in mitochondrial dysfunction.

A Barth Syndrome Patient-Derived D75H Point Mutation in TAFAZZIN Drives Progressive Cardiomyopathy in Mice

Cardiomyopathy is the predominant defect in Barth syndrome (BTHS) and is caused by a mutation of the X-linked Tafazzin (TAZ) gene, which encodes an enzyme responsible for remodeling mitochondrial cardiolipin. Despite the known importance of mitochondrial dysfunction in BTHS, how specific TAZ mutations cause diverse BTHS heart phenotypes remains poorly understood. We generated a patient-tailored CRISPR/Cas9 knock-in mouse allele (TazPM) that phenocopies BTHS clinical traits. As TazPM males express a stable mutant protein, we assessed cardiac metabolic dysfunction and mitochondrial changes and identified temporally altered cardioprotective signaling effectors. Specifically, juvenile TazPM males exhibit mild left ventricular dilation in systole but have unaltered fatty acid/amino acid metabolism and normal adenosine triphosphate (ATP). This occurs in concert with a hyperactive p53 pathway, elevation of cardioprotective antioxidant pathways, and induced autophagy-mediated early senescence in juvenile TazPM hearts. However, adult TazPM males exhibit chronic heart failure with reduced growth and ejection fraction, cardiac fibrosis, reduced ATP, and suppressed fatty acid/amino acid metabolism. This biphasic changeover from a mild-to-severe heart phenotype coincides with p53 suppression, downregulation of cardioprotective antioxidant pathways, and the onset of terminal senescence in adult TazPM hearts. Herein, we report a BTHS genotype/phenotype correlation and reveal that absent Taz acyltransferase function is sufficient to drive progressive cardiomyopathy.

Mitochondrial complex-1 as a therapeutic target for cardiac diseases

Mitochondrial dysfunction is critical for the development and progression of cardiovascular diseases (CVDs). Complex-1 (CI) is an essential component of the mitochondrial electron transport chain that participates in oxidative phosphorylation and energy production. CI is the largest multisubunit complex (~ 1 Mda) and comprises 45 protein subunits encoded by seven mt-DNA genes and 38 nuclear genes. These subunits function as the enzyme nicotinamide adenine dinucleotide  hydrogen (NADH): ubiquinone oxidoreductase. CI dysregulation has been implicated in various CVDs, including heart failure, ischemic heart disease, pressure overload, hypertrophy, and cardiomyopathy. Several studies demonstrated that impaired CI function contributes to increased oxidative stress, altered calcium homeostasis, and mitochondrial DNA damage in cardiac cells, leading to cardiomyocyte dysfunction and apoptosis. CI dysfunction has been associated with endothelial dysfunction, inflammation, and vascular remodeling, critical processes in developing atherosclerosis and hypertension. Although CI is crucial in physiological and pathological conditions, no potential therapeutics targeting CI are available to treat CVDs. We believe that a lack of understanding of CI's precise mechanisms and contributions to CVDs limits the development of therapeutic strategies. In this review, we comprehensively analyze the role of CI in cardiovascular health and disease to shed light on its potential therapeutic target role in CVDs.

Analysis of methylation-driven genes for predicting the prognosis of patients with oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC) is a highly aggressive malignancy that is characterized by early distant metastasis and poor prognosis. DNA methylation plays an important role in the etiology and pathogenesis of OSCC. This study aimed to identify methylation-driven genes through bioinformatics analysis as potential biomarkers for early diagnosis and prognostic assessment of OSCC.

Methods

Methylation data, RNA sequencing (RNA-seq) data and clinical prognosis information of OSCC patients were retrieved from The Cancer Genome Atlas (TCGA) database. The R packages MethylMix were employed to analyze the correlation between methylation status and corresponding gene expression in tumor and normal tissues to obtain methylation-driven genes. Univariate Cox regression analysis was developed to further screen methylation-driven genes associated with the prognosis of OSCC patients. Subsequently, multivariate Cox regression analysis was utilized to construct a linear prognostic risk prediction model. Furthermore, a combined survival analysis integrating methylation and gene expression was performed to investigate the prognostic value.

Results

A total of 374 differentially expressed methylation-driven genes were identified. Seven methylation-driven genes (BST2, KRT15, ZNF134, NT5E, GSTA7P, NAPRT, and GOLPH3L) were found to be significantly associated with patient prognosis. Additionally, four methylation-driven genes (BST2, KRT15, ZNF134 and NAPRT) were used to construct a linear prognostic risk prediction model for OSCC patients. Furthermore, a combined Kaplan-Meier survival analysis revealed that three methylation-driven genes (ZKSCAN7, MFF, ZNF134) alone can be used as independent prognostic markers or drug targets.

Conclusions

Our findings facilitate a better understanding of molecular mechanisms of OSCC and provide potential biomarkers of early diagnosis, precision treatment and prognosis evaluation.

Lack of detectable sex differences in the mitochondrial function of Caenorhabditis elegans

BACKGROUND

Sex differences in mitochondrial function have been reported in multiple tissue and cell types. Additionally, sex-variable responses to stressors including environmental pollutants and drugs that cause mitochondrial toxicity have been observed. The mechanisms that establish these differences are thought to include hormonal modulation, epigenetic regulation, double dosing of X-linked genes, and the maternal inheritance of mtDNA. Understanding the drivers of sex differences in mitochondrial function and being able to model them in vitro is important for identifying toxic compounds with sex-variable effects. Additionally, understanding how sex differences in mitochondrial function compare across species may permit insight into the drivers of these differences, which is important for basic biology research. This study explored whether Caenorhabditis elegans, a model organism commonly used to study stress biology and toxicology, exhibits sex differences in mitochondrial function and toxicant susceptibility. To assess sex differences in mitochondrial function, we utilized four male enriched populations (N2 wild-type male enriched, fog-2(q71), him-5(e1490), and him-8(e1498)). We performed whole worm respirometry and determined whole worm ATP levels and mtDNA copy number. To probe whether sex differences manifest only after stress and inform the growing use of C. elegans as a mitochondrial health and toxicologic model, we also assessed susceptibility to a classic mitochondrial toxicant, rotenone.

RESULTS

We detected few to no large differences in mitochondrial function between C. elegans sexes. Though we saw no sex differences in vulnerability to rotenone, we did observe sex differences in the uptake of this lipophilic compound, which may be of interest to those utilizing C. elegans as a model organism for toxicologic studies. Additionally, we observed altered non-mitochondrial respiration in two him strains, which may be of interest to other researchers utilizing these strains.

CONCLUSIONS

Basal mitochondrial parameters in male and hermaphrodite C. elegans are similar, at least at the whole-organism level, as is toxicity associated with a mitochondrial Complex I inhibitor, rotenone. Our data highlights the limitation of using C. elegans as a model to study sex-variable mitochondrial function and toxicological responses.

Resveratrol mediates mitochondrial function through the sirtuin 3 pathway to improve abnormal metabolic remodeling in atrial fibrillation

This study investigated the impact of resveratrol on abnormal metabolic remodeling in atrial fibrillation (AF) and explored potential molecular mechanisms. An AF cell model was established by high-frequency electrical stimulation of HL-1 atrial muscle cells. Resveratrol concentrations were optimized using CCK-8 and flow cytometry. AF-induced increases in ROS and mitochondrial calcium, along with decreased adenosine triphosphate (ATP) and mitochondrial membrane potential, were observed. Resveratrol mitigated these changes and maintained normal mitochondrial morphology. Moreover, resveratrol acted through the SIRT3-dependent pathway, as evidenced by its ability to suppress AF-induced acetylation of key metabolic enzymes. SIRT3 overexpression controls acetylation modifications, suggesting its regulatory role. In conclusion, resveratrol's SIRT3-dependent pathway intervenes in AF-induced mitochondrial dysfunction, presenting a potential therapeutic avenue for AF-related metabolic disorders. This study sheds light on the role of resveratrol in mitigating AF-induced mitochondrial remodeling and highlights its potential as a novel treatment for AF.

Disturbance of mitochondrial dynamics in myocardium of broilers with pulmonary hypertension syndrome

1. The following study investigated the relationship between pulmonary hypertension syndrome (PHS) and mitochondrial dynamics in broiler cardiomyocytes.2. An animal model for PHS was established by injecting broiler chickens with CM-32 cellulose particles. Broiler myocardial cells were cultured under hypoxic conditions to establish an in vitro model. The ascites heart index, histomorphology, mitochondrial ultrastructure, and mitochondrial dynamic-related gene and protein expression were evaluated.3. The myocardial fibres from PHS broilers had wider spaces and were wavy and twisted and the number of mitochondria increased. Compared with the control group, the gene and protein expression levels were decreased for Opa1, Mfn1, and Mfn2 in the myocardium of PHS broilers. The gene and protein expression was significantly increased for Drp1 and Mff.4. This study showed that PHS in broilers may cause myocardial mitochondrial dysfunction, specifically by diminishing mitochondrial fusion and enhancing fission, causing disturbances in the mitochondrial dynamics of the heart.

Role of non-coding RNAs and exosomal non-coding RNAs in vasculitis: A narrative review

A category of very uncommon systemic inflammatory blood vessel illnesses known as vasculitides. The pathogenesis and etiology of vasculitis are still poorly known. Despite all of the progress made in understanding the genetics and causes behind vasculitis, there is still more to learn. Epigenetic dysregulation is a significant contributor to immune-mediated illnesses, and epigenetic aberrancies in vasculitis are becoming more widely acknowledged. Less than 2 % of the genome contains protein-encoding DNA. Studies have shown that a variety of RNAs originating from the non-coding genome exist. Long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) have attracted the most attention in recent years as they are becoming more and more important regulators of different biological processes, such as diseases of the veins. Extracellular vehicles (EVs) such as exosomes, are membrane-bound vesicular structures that break free either during programmed cell death, such as apoptosis, pyroptosis, and necroptosis or during cell activation. Exosomes may be involved in harmful ways in inflammation, procoagulation, autoimmune reactions, endothelial dysfunction/damage, intimal hyperplasia and angiogenesis, all of which may be significant in vasculitis. Herein, we summarized various non-coding RNAs that are involved in vasculitides pathogenesis. Moreover, we highlighted the role of exosomes in vasculitides.

Cellular Senescence, Mitochondrial Dysfunction, and Their Link to Cardiovascular Disease

Cardiovascular diseases (CVDs), a group of disorders affecting the heart or blood vessels, are the primary cause of death worldwide, with an immense impact on patient quality of life and disability. According to the World Health Organization, CVD takes an estimated 17.9 million lives each year, where more than four out of five CVD deaths are due to heart attacks and strokes. In the decades to come, an increased prevalence of age-related CVD, such as atherosclerosis, coronary artery stenosis, myocardial infarction (MI), valvular heart disease, and heart failure (HF) will contribute to an even greater health and economic burden as the global average life expectancy increases and consequently the world's population continues to age. Considering this, it is important to focus our research efforts on understanding the fundamental mechanisms underlying CVD. In this review, we focus on cellular senescence and mitochondrial dysfunction, which have long been established to contribute to CVD. We also assess the recent advances in targeting mitochondrial dysfunction including energy starvation and oxidative stress, mitochondria dynamics imbalance, cell apoptosis, mitophagy, and senescence with a focus on therapies that influence both and therefore perhaps represent strategies with the most clinical potential, range, and utility.

Ginsenoside Rb1 alleviates 3-MCPD-induced renal cell pyroptosis by activating mitophagy

Ginsenoside Rb1 (Gs-Rb1) is among the most significant effective pharmacological components in ginseng. 3-monochloropropane-1,2-diol (3-MCPD), a chloropropanol-like contaminant, is produced in the production of refined oils and thermal processing of food. Pyroptosis is a type of programmed cell death triggered by inflammasomes. Excessive pyroptosis causes kidney injury and inflammation. Previous studies have revealed that 3-MCPD induced pyroptosis in mice and NRK-52E cells. In the present study, we find that Gs-Rb1 attenuates 3-MCPD-induced renal cell pyroptosis by assaying GSDMD-N, caspase-1, IL-18, and IL-1β in mice and NRK-52E cells. In further mechanistic studies, we show that Gs-Rb1 removes damaged mitochondria via mitophagy and reduces intracellular reactive oxygen species (ROS) generation, therefore alleviating 3-MCPD-induced NOD-like receptor family pyrin domain containing 3 (NLRP3) activation and pyroptosis. The above results are further validated by the addition of autophagy inhibitor Chloroquine (CQ) and mitophagy inhibitor Cyclosporin A (CsA). Afterward, we explore how Gs-Rb1 activated mitophagy in vitro. We determine that Gs-Rb1 enhances the protein expression and nuclear translocation of Transcription factor EB (TFEB). However, silencing of the TFEB gene by small interfering RNA technology reverses the role of Gs-Rb1 in activating mitophagy. Therefore, we conclude that 3-MCPD damages mitochondria and leads to ROS accumulation, which causes NLRP3 activation and pyroptosis in ICR mice and NRK-52E cells, while Gs-Rb1 mitigates this phenomenon via the TFEB-mitophagy pathway. Our findings may provide new insights for understanding the molecular mechanisms by which Gs-Rb1 mitigates renal injury.

The Arylamine N-Acetyltransferases as Therapeutic Targets in Metabolic Diseases Associated with Mitochondrial Dysfunction

In humans, there are two arylamine N-acetyltransferase genes that encode functional enzymes (NAT1 and NAT2) as well as one pseudogene, all of which are located together on chromosome 8. Although they were first identified by their role in the acetylation of drugs and other xenobiotics, recent studies have shown strong associations for both enzymes in a variety of diseases, including cancer, cardiovascular disease, and diabetes. There is growing evidence that this association may be causal. Consistently, NAT1 and NAT2 are shown to be required for healthy mitochondria. This review discusses the current literature on the role of both NAT1 and NAT2 in mitochondrial bioenergetics. It will attempt to relate our understanding of the evolution of the two genes with biologic function and then present evidence that several major metabolic diseases are influenced by NAT1 and NAT2. Finally, it will discuss current and future approaches to inhibit or enhance NAT1 and NAT2 activity/expression using small-molecule drugs. SIGNIFICANCE STATEMENT: The arylamine N-acetyltransferases (NATs) NAT1 and NAT2 share common features in their associations with mitochondrial bioenergetics. This review discusses mitochondrial function as it relates to health and disease, and the importance of NAT in mitochondrial function and dysfunction. It also compares NAT1 and NAT2 to highlight their functional similarities and differences. Both NAT1 and NAT2 are potential drug targets for diseases where mitochondrial dysfunction is a hallmark of onset and progression.

PINK1 dominated mitochondria associated genes signature predicts abdominal aortic aneurysm with metabolic syndrome

Abdominal aortic aneurysm (AAA) is typically asymptomatic but a devastating cardiovascular disorder, with overall mortality exceeding 80 % once it ruptures. Some patients with AAA may also have comorbid metabolic syndrome (MS), suggesting a potential common underlying pathogenesis. Mitochondrial dysfunction has been reported as a key factor contributing to the deterioration of both AAA and MS. However, the intricate interplay between metabolism and mitochondrial function, both contributing to the development of AAA, has not been thoroughly explored. In this study, we identified candidate genes related to mitochondrial function in AAA and MS. Subsequently, we developed a nomoscore model comprising hub genes (PINK1, ACSL1, CYP27A1, and SLC25A11), identified through the application of two machine learning algorithms, to predict AAA. We observed a marked disparity in immune infiltration profiles between high- and low-nomoscore groups. Furthermore, we confirmed a significant upregulation of the expression of the four hub genes in AAA tissues. Among these, ACSL1 showed relatively higher expression in LPS-treated RAW264.7 cell lines, while CYP27A1 exhibited a notable decrease. Moreover, SLC25A11 displayed a significant upregulation in AngII-treated VSMCs. Conversely, the expression level of PINK1 declined in LPS-stimulated RAW264.7 cell lines but significantly increased in AngII-treated VSMCs. In vivo experiments revealed that the activation of PINK1-mediated mitophagy inhibited the development of AAA in mice. In this current study, we have innovatively identified four mitochondrial function-related genes through integrated bioinformatic analysis. This discovery sheds light on the regulatory mechanisms and unveils promising therapeutic targets for the comorbidity of AAA and MS.

Aging-induced mitochondrial dysfunction: two distinct populations of mitochondria versus a combined population

Mitochondrial function in aged hearts is impaired, and studies of isolated mitochondria are commonly used to assess their function. The two populations of cardiac mitochondria, subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM), are affected by aging. However, the yield of these mitochondria, particularly SSM, is limited in the mouse heart because of the smaller heart size. To address this issue, the authors developed a method to isolate a mixed population (MIX) of SSM and IFM mitochondria from a single mouse heart. The aim of the study was to compare the mitochondrial function between SSM, IFM, and the MIX population from young and aged mouse hearts. The MIX population had a higher yield of total protein and citrate synthase activity from both young and aged hearts compared with the individual yields of SSM or IFM. Oxidative phosphorylation (OXPHOS) decreased in aged SSM and IFM compared with young SSM and IFM, as well as in the MIX population isolated from aged hearts compared with young hearts, when using complex I or IV substrates. Furthermore, aging barely affected the sensitivity to mitochondrial permeability transition pore (MPTP) opening in SSM, whereas the sensitivity was increased in IFM isolated from aged hearts and in the MIX population from aged hearts compared with the corresponding populations isolated from young hearts. These results suggest that mitochondrial dysfunction exists in aged hearts and the isolation of a MIX population of mitochondria from the mouse heart is a potential approach to studying mitochondrial function in the mouse heart.NEW & NOTEWORTHY We developed two methods to isolate mitochondria from a single mouse heart. We compared mitochondrial function in young and aged mice using mitochondria isolated with different methods. Both methods can be successfully used to isolate cardiac mitochondria from single mouse hearts. Our results provide the flexibility to isolate mitochondria from a single mouse heart based on the purpose of the study.

Drug-induced atrial fibrillation. A narrative review of a forgotten adverse effect

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with an increased morbidity and mortality. There is clinical evidence that an increasing number of cardiovascular and non-cardiovascular drugs, mainly anticancer drugs, can induce AF either in patients with or without pre-existing cardiac disorders, but drug-induced AF (DIAF) has not received the attention that it might deserve. In many cases DIAF is asymptomatic and paroxysmal and patients recover sinus rhythm spontaneously, but sometimes, DIAF persists, and it is necessary to perform a cardioversion. Furthermore, DIAF is not mentioned in clinical guidelines on the treatment of AF. The risk of DIAF increases in elderly and in patients treated with polypharmacy and with risk factors and comorbidities that commonly coexist with AF. This is the case of cancer patients. Under these circumstances ascribing causality of DIAF to a given drug often represents a clinical challenge. We review the incidence, the pathophysiological mechanisms, risk factors, clinical relevance, and treatment of DIAF. Because of the limited information presently available, further research is needed to obtain a deeper insight into DIAF. Meanwhile, it is important that clinicians are aware of the problem that DIAF represents, recognize which drugs may cause DIAF, and consider the possibility that a drug may be responsible for a new-onset AF episode.

Glutaminase 1 plays critical roles in myelodysplastic syndrome and acute myeloid leukemia cells

BACKGROUND

Myelodysplastic syndrome (MDS) features bone marrow failure and a heightened risk of evolving into acute myeloid leukemia (AML), increasing with age and reducing overall survival. Given the unfavorable outcomes of MDS, alternative treatments are necessary. Glutamine, the most abundant amino acid in the blood, is metabolized first by the enzyme glutaminase (GLS).

OBJECTIVES

To investigate whether GLS is involved in the progression of MDS. The efficacy of GLS inhibitors (CB839 or IPN60090) and BCL2 inhibitor venetoclax was also examined.

METHODS

We employed GLS inhibitors (CB839, IPN60090) and the BCL2 inhibitor venetoclax, prepared as detailed. MDS and AML cell lines were cultured under standard and modified (hypoxic, glutamine-free) conditions. Viability, proliferation, and caspase activity were assessed with commercial kits. RT-PCR quantified gene expression post-shRNA transfection. Mitochondrial potential, ATP levels, proteasome activity, and metabolic functions were evaluated using specific assays. Statistical analyses (t-tests, ANOVA) validated the findings.

RESULTS

The glutamine-free medium inhibited the growth of MDS cells. GLS1 expression was higher in AML cells than in normal control samples (GSE15061), whereas GLS2 expression was not. Treatment of MDS and AML cells for 72 h was inhibited in a dose-dependent manner by GLS inhibitors. Co-treatment with the B-cell lymphoma 2 (BCL2) inhibitor venetoclax and GLS inhibitors increased potency. Cells transfected with GLS1 short hairpin RNA showed suppressed proliferation under hypoxic conditions and increased sensitivity to venetoclax.

CONCLUSIONS

Targeting glutaminolysis and BCL2 inhibition enhances the therapeutic efficacy and has been proposed as a novel strategy for treating high-risk MDS and AML.

The cyclin-dependent kinase inhibitor abemaciclib-induced hepatotoxicity: Insight on the molecular mechanisms in HepG2/THP-1 co-culture model

Drug-induced liver injury (DILI) is one of the widespread causes of liver injury and immune system plays important role. Abemaciclib (ABE) is a cyclin-dependent kinase inhibitor used as monotherapy or combination therapy in the treatment of breast cancer. Like other kinase inhibitors, the underlying mechanisms of ABE-induced hepatotoxicity are not completely known yet. In the current study, hepatotoxicity of ABE was evaluated with HepG2/THP-1 co-culture model which has been developed in recent years for the evaluation of DILI potential. Following ABE treatment, oxidative stress, mitochondrial damage, cytokine secretion levels, apoptotic/necrotic cell death were determined. According to our results, ROS production along with GSH depletion was observed in HepG2 cells after ABE treatment. ABE promoted secretion of pro-inflammatory mediators (TNF-α and MCP-1) and declined anti-inflammatory cytokine IL-10 release. Besides, NFKβ and JNK1 protein expression levels increased following ABE treatment. ABE enhanced intracellular calcium levels, induced early apoptotic and necrotic cell deaths in HepG2 cells. Furthermore, the changes in some mitochondrial parameters including a reducement in intracellular ATP levels and complex V activity; hyperpolarized mitochondrial membrane potential and enhanced mitochondrial ROS levels were observed, whereas mitochondrial mass did not show any differences after ABE treatments. Therefore, ABE-induced hepatotoxic effects is probably via oxidative stress, inflammatory response and necrotic cell death rather than direct mitochondrial toxicity. In conclusion; the study makes a significant contribution to strengthening the infrastructure we have on in vitro toxicity mechanism evaluations, which are the basis of preclinical toxicity studies.

Evaluation of in vitro effects of ifosfamide drug on mitochondrial functions using isolated mitochondria obtained from vital organs

Mitochondrial toxicity has been shown to contribute to a variety of organ toxicities such as, brain, heart, kidney, and liver. Ifosfamide (IFO) as an anticancer drug, is associated with increased risk of neurotoxicity, cardiotoxicity nephrotoxicity, hepatotoxicity, and hemorrhagic cystitis. The aim of this study was to evaluate the direct effect of IFO on isolated mitochondria obtained from the rat brain, heart, kidney, and liver. Mitochondria were isolated with mechanical lysis and differential centrifugation from different organs and treated with various concentrations of IFO. Using biochemical and flowcytometry assays, we evaluated mitochondrial succinate dehydrogenase (SDH) activity, mitochondrial swelling, lipid peroxidation, reactive oxygen species (ROS) production, and mitochondrial membrane potential (MMP). Our data showed that IFO did not cause deleterious alterations in mitochondrial functions, mitochondrial swelling, lipid peroxidation ROS formation, and MMP collapse in mitochondria isolated from brain, heart, kidney, and liver. Altogether, the data showed that IFO is not directly toxic in mitochondria isolated from brain, heart, kidney, and liver. This study proved that mitochondria alone does not play the main role in the toxicity of IFO, and suggests to reduce the toxicity of this drug, other pathways resulting in the production of toxic metabolites should be considered.

Long-term super-resolution inner mitochondrial membrane imaging with a lipid probe

The inner mitochondrial membrane (IMM) generates power to drive cell function, and its dynamics control mitochondrial health and cellular homeostasis. Here, we describe the cell-permeant, lipid-like small molecule MAO-N3 and use it to assemble high-density environmentally sensitive (HIDE) probes that selectively label and image the IMM in live cells and multiple cell states. MAO-N3 pairs with strain-promoted azide-alkyne click chemistry-reactive fluorophores to support HIDE imaging using confocal, structured illumination, single-molecule localization and stimulated emission depletion microscopy, all with significantly improved resistance to photobleaching. These probes generate images with excellent spatial and temporal resolution, require no genetic manipulations, are non-toxic in model cell lines and primary cardiomyocytes (even under conditions that amplify the effects of mitochondrial toxins) and can visualize mitochondrial dynamics for 12.5 h. This probe will enable comprehensive studies of IMM dynamics with high temporal and spatial resolution.

Riboflavin protects against heart failure via SCAD-dependent DJ-1-Keap1-Nrf2 signalling pathway

BACKGROUND AND PURPOSE

Our recent studies have shown that flavin adenine dinucleotide (FAD) exerts cardiovascular protective effects by supplementing short-chain acyl-CoA dehydrogenase (SCAD). The current study aimed to elucidate whether riboflavin (the precursor of FAD) could improve heart failure via activating SCAD and the DJ-1-Keap1-Nrf2 signalling pathway.

EXPERIMENTAL APPROACH

Riboflavin treatment was given to the mouse transverse aortic constriction (TAC)-induced heart failure model. Cardiac structure and function, energy metabolism and apoptosis index were assessed, and relevant signalling proteins were analysed. The mechanisms underlying the cardioprotection by riboflavin were analysed in the cell apoptosis model induced by tert-butyl hydroperoxide (tBHP).

KEY RESULTS

In vivo, riboflavin ameliorated myocardial fibrosis and energy metabolism, improved cardiac dysfunction and inhibited oxidative stress and cardiomyocyte apoptosis in TAC-induced heart failure. In vitro, riboflavin ameliorated cell apoptosis in H9C2 cardiomyocytes by decreasing reactive oxygen species (ROS). At the molecular level, riboflavin significantly restored FAD content, SCAD expression and enzymatic activity, activated DJ-1 and inhibited the Keap1-Nrf2/HO1 signalling pathway in vivo and in vitro. SCAD knockdown exaggerated the tBHP-induced DJ-1 decrease and Keap1-Nrf2/HO1 signalling pathway activation in H9C2 cardiomyocytes. The knockdown of SCAD abolished the anti-apoptotic effects of riboflavin on H9C2 cardiomyocytes. DJ-1 knockdown hindered SCAD overexpression anti-apoptotic effects and regulation on Keap1-Nrf2/HO1 signalling pathway in H9C2 cardiomyocytes.

CONCLUSIONS AND IMPLICATIONS

Riboflavin exerts cardioprotective effects on heart failure by improving oxidative stress and cardiomyocyte apoptosis via FAD to stimulate SCAD and then activates the DJ-1-Keap1-Nrf2 signalling pathway.

Mitophagy in human health, ageing and disease

Maintaining optimal mitochondrial function is a feature of health. Mitophagy removes and recycles damaged mitochondria and regulates the biogenesis of new, fully functional ones preserving healthy mitochondrial functions and activities. Preclinical and clinical studies have shown that impaired mitophagy negatively affects cellular health and contributes to age-related chronic diseases. Strategies to boost mitophagy have been successfully tested in model organisms, and, recently, some have been translated into clinics. In this Review, we describe the basic mechanisms of mitophagy and how mitophagy can be assessed in human blood, the immune system and tissues, including muscle, brain and liver. We outline mitophagy's role in specific diseases and describe mitophagy-activating approaches successfully tested in humans, including exercise and nutritional and pharmacological interventions. We describe how mitophagy is connected to other features of ageing through general mechanisms such as inflammation and oxidative stress and forecast how strengthening research on mitophagy and mitophagy interventions may strongly support human health.

Clinical chorioamnionitis at term is characterized by changes in the plasma concentration of CHCHD2/MNRR1, a mitochondrial protein

OBJECTIVE

Mitochondrial dysfunction was observed in acute systemic inflammatory conditions such as sepsis and might be involved in sepsis-induced multi-organ failure. Coiled-Coil-Helix-Coiled-Coil-Helix Domain Containing 2 (CHCHD2), also known as Mitochondrial Nuclear Retrograde Regulator 1 (MNRR1), a bi-organellar protein located in the mitochondria and the nucleus, is implicated in cell respiration, survival, and response to tissue hypoxia. Recently, the reduction of the cellular CHCHD2/MNRR1 protein, as part of mitochondrial dysfunction, has been shown to play a role in the amplification of inflammatory cytokines in a murine model of lipopolysaccharide-induced systemic inflammation. The aim of this study was to determine whether the plasma concentration of CHCHD2/MNRR1 changed during human normal pregnancy, spontaneous labor at term, and clinical chorioamnionitis at term.

METHODS

We conducted a cross-sectional study that included the following groups: 1) non-pregnant women (n = 17); 2) normal pregnant women at various gestational ages from the first trimester until term (n = 110); 3) women at term with spontaneous labor (n = 50); and 4) women with clinical chorioamnionitis at term in labor (n = 25). Plasma concentrations of CHCHD2/MNRR1 were assessed by an enzyme-linked immunosorbent assay.

RESULTS

1) Pregnant women at term in labor with clinical chorioamnionitis had a significantly higher plasma CHCHD2/MNRR1 concentration than those in labor without chorioamnionitis (p = .003); 2) CHCHD2/MNRR1 is present in the plasma of healthy non-pregnant and normal pregnant women without significant differences in its plasma concentrations between the two groups; 3) there was no correlation between maternal plasma CHCHD2/MNRR1 concentration and gestational age at venipuncture; and 4) plasma CHCHD2/MNRR1 concentration was not significantly different in women at term in spontaneous labor compared to those not in labor.

CONCLUSIONS

CHCHD2/MNRR1 is physiologically present in the plasma of healthy non-pregnant and normal pregnant women, and its concentration does not change with gestational age and parturition at term. However, plasma CHCHD2/MNRR1 is elevated in women at term with clinical chorioamnionitis. CHCHD2/MNRR1, a novel bi-organellar protein located in the mitochondria and the nucleus, is released into maternal plasma during systemic inflammation.

Recent advances in metal-organic frameworks: Synthesis, application and toxicity

Metal-organic frameworks (MOFs) are a new class of crystalline porous hybrid materials with high porosity, large specific surface area and adjustable channel structure and biocompatibility, which are being investigated with increasing interest for energy storage and conversion, gas adsorption/separation, catalysis, sensing and biomedicine. However, the practical applications of MOFs make them release into the environment inevitable, posing a threat to humans and organisms. In this article, we cover advances in the currently available MOFs synthesis methods and the emerging applications of MOFs, especially in the biomedical field (therapeutic agents and bioimaging). Additionally, after evaluating the current status of main exposure routes and affecting factors in the field of MOFs-toxicity, the molecular mechanism is also clarified and identified. Knowledge gaps are identified from such a summarization and frontier development are explored for MOFs. Afterwards, we also present the limitations, challenges, and future perspectives in the study of the entire life cycle of MOFs. This review emphasizes the need for a more targeted discussion of the latest, widely used and effective versatile material class in order to exploit the full potential of high-performance and non-toxicity MOFs in the future.

Mitoguardin 1 and 2 promote granulosa cell proliferation by activating AKT and regulating the Hippo-YAP1 signaling pathway

Mitochondria have been identified to be involved in oxidative phosphorylation, lipid metabolism, cell death, and cell proliferation. Previous studies have demonstrated that mitoguardin (Miga), a mitochondrial protein that governs mitochondrial fusion, mitochondria-endoplasmic reticulum (ER) contacts, lipid formation, and autophagy, is crucial for ovarian endocrine and follicular development. Nevertheless, whether mammalian MIGA1 or MIGA2 (MIGA1,-2) regulates ovarian granulosa cell proliferation remains unclear. This study revealed that mammalian MIGA1,-2 promotes cell proliferation and regulates the phosphorylation and localization of Yes-associated protein 1 (YAP1) in ovarian granulosa cells. MIGA2 upregulation resulted in reduced YAP1 activity, while MIGA2 removal led to increased YAP1 activity. Further analysis indicated that MIGA1,-2 regulated YAP1 via the Hippo signaling pathway and regulated protein kinase B (AKT) activity in collaboration with YAP1. In addition, lysophosphatidic acid (LPA) regulated MIGA2 expression and AKT activity by activating YAP1. Briefly, we demonstrated that the mitochondrial MIGA1 and MIGA2, especially MIGA2, promoted cellular proliferation by activating AKT and regulating the Hippo/YAP1 signaling pathway in ovarian granulosa cells, which may contribute to the molecular pathogenesis of reproductive endocrine diseases, such as polycystic ovary syndrome (PCOS).

NMR-Based Mitochondria Metabolomic Profiling: A New Approach To Reveal Cancer-Associated Alterations

Studying metabolism may assist in understanding the relationship between normal and dysfunctional mitochondrial activity and various diseases, such as neurodegenerative, cardiovascular, autoimmune, psychiatric, and cancer. Nuclear magnetic resonance-based metabolomics represents a powerful method to characterize the chemical content of complex samples and has been successfully applied to studying a range of conditions. However, an optimized methodology is lacking for analyzing isolated organelles, such as mitochondria. In this study, we report the development of a protocol to metabolically profile mitochondria from healthy, tumoral, and metastatic tissues. Encouragingly, this approach provided quantitative information about up to 45 metabolites in one comprehensive and robust analysis. Our results revealed significant differences between whole-cell and mitochondrial metabolites, which supports a more refined approach to metabolic analysis. We applied our optimized methodology to investigate aggressive and metastatic breast cancer in mouse tissues, discovering that lung mitochondria exhibit an altered metabolic fingerprint. Specific amino acids, organic acids, and lipids showed significant increases in levels when compared with mitochondria from healthy tissues. Our optimized methodology could promote a better understanding of the molecular mechanisms underlying breast cancer aggressiveness and mitochondrial-related diseases and support the optimization of new advanced therapies.

Mitochondrial quality control in health and cardiovascular diseases

Cardiovascular diseases (CVDs) are one of the primary causes of mortality worldwide. An optimal mitochondrial function is central to supplying tissues with high energy demand, such as the cardiovascular system. In addition to producing ATP as a power source, mitochondria are also heavily involved in adaptation to environmental stress and fine-tuning tissue functions. Mitochondrial quality control (MQC) through fission, fusion, mitophagy, and biogenesis ensures the clearance of dysfunctional mitochondria and preserves mitochondrial homeostasis in cardiovascular tissues. Furthermore, mitochondria generate reactive oxygen species (ROS), which trigger the production of pro-inflammatory cytokines and regulate cell survival. Mitochondrial dysfunction has been implicated in multiple CVDs, including ischemia-reperfusion (I/R), atherosclerosis, heart failure, cardiac hypertrophy, hypertension, diabetic and genetic cardiomyopathies, and Kawasaki Disease (KD). Thus, MQC is pivotal in promoting cardiovascular health. Here, we outline the mechanisms of MQC and discuss the current literature on mitochondrial adaptation in CVDs.

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.