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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. Summary 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.

Aims Aging entails profound immunological transformations that can impact myocardial homeostasis and predispose to heart failure. However, preclinical research in the immune-cardiology field is mostly conducted in young healthy animals, which potentially weakens its translational relevance. Herein, we sought to investigate how the aging T-cell compartment associates with changes in myocardial cell biology in aged mice. Methods and results We phenotyped the antigen-experienced effector/memory T cells purified from heart-draining lymph nodes of 2-, 6-, 12-, and 18-month-old C57BL/6J mice using single-cell RNA/T cell receptor sequencing. Simultaneously, we profiled all non-cardiomyocyte cell subsets purified from 2- to 18-month-old hearts and integrated our data with publicly available cardiomyocyte single-cell sequencing datasets. Some of these findings were confirmed at the protein level by flow cytometry. With aging, the heart-draining lymph node and myocardial T cells underwent clonal expansion and exhibited an up-regulated pro-inflammatory transcription signature, marked by an increased interferon-γ (IFN-γ) production. In parallel, all major myocardial cell populations showed increased IFN-γ responsive signature with aging. In the aged cardiomyocytes, a stronger IFN-γ response signature was paralleled by the dampening of expression levels of transcripts related to most metabolic pathways, especially oxidative phosphorylation. Likewise, induced pluripotent stem cells-derived cardiomyocytes exposed to chronic, low grade IFN-γ treatment showed a similar inhibition of metabolic activity. Conclusions By investigating the paired age-related alterations in the T cells found in the heart and its draining lymph nodes, we provide evidence for increased myocardial IFN-γ signaling with age, which is associated with inflammatory and metabolic shifts typically seen in heart failure.

Background: Barth syndrome (BTHS) is caused by mutations of the gene encoding tafazzin, which catalyzes maturation of mitochondrial cardiolipin and often manifests with systolic dysfunction during early infancy. Beyond the first months of life, BTHS cardiomyopathy typically transitions to a phenotype of diastolic dysfunction with preserved ejection fraction, blunted contractile reserve during exercise, and arrhythmic vulnerability. Previous studies traced BTHS cardiomyopathy to mitochondrial formation of reactive oxygen species (ROS). Because mitochondrial function and ROS formation are regulated by excitation-contraction coupling, integrated analysis of mechano-energetic coupling is required to delineate the pathomechanisms of BTHS cardiomyopathy. Methods: We analyzed cardiac function and structure in a mouse model with global knockdown of tafazzin ( Taz -KD) compared with wild-type littermates. Respiratory chain assembly and function, ROS emission, and Ca 2+ uptake were determined in isolated mitochondria. Excitation-contraction coupling was integrated with mitochondrial redox state, ROS, and Ca 2+ uptake in isolated, unloaded or preloaded cardiac myocytes, and cardiac hemodynamics analyzed in vivo. Results: Taz -KD mice develop heart failure with preserved ejection fraction (>50%) and age-dependent progression of diastolic dysfunction in the absence of fibrosis. Increased myofilament Ca 2+ affinity and slowed cross-bridge cycling caused diastolic dysfunction, in part, compensated by accelerated diastolic Ca 2+ decay through preactivated sarcoplasmic reticulum Ca 2 + -ATPase. Taz deficiency provoked heart-specific loss of mitochondrial Ca 2+ uniporter protein that prevented Ca 2+ -induced activation of the Krebs cycle during β-adrenergic stimulation, oxidizing pyridine nucleotides and triggering arrhythmias in cardiac myocytes. In vivo, Taz -KD mice displayed prolonged QRS duration as a substrate for arrhythmias, and a lack of inotropic response to β-adrenergic stimulation. Cellular arrhythmias and QRS prolongation, but not the defective inotropic reserve, were restored by inhibiting Ca 2+ export through the mitochondrial Na + /Ca 2+ exchanger. All alterations occurred in the absence of excess mitochondrial ROS in vitro or in vivo. Conclusions: Downregulation of mitochondrial Ca 2+ uniporter, increased myofilament Ca 2+ affinity, and preactivated sarcoplasmic reticulum Ca 2+ -ATPase provoke mechano-energetic uncoupling that explains diastolic dysfunction and the lack of inotropic reserve in BTHS cardiomyopathy. Furthermore, defective mitochondrial Ca 2+ uptake provides a trigger and a substrate for ventricular arrhythmias. These insights can guide the ongoing search for a cure of this orphaned disease.

The observed changes in the periarticular space may be caused by both mechanical action and biological reactions. Periprosthetic infections are the most common cause of loosening and destructive changes in the joints, however, the diagnosis of an aseptic reaction is not always fully obvious. Micromovements between the implant and the surrounding bone can cause remodeling of the bone trabeculae and migration of fibroblasts into the voids between the implant surface and the bone. In addition, repetitive stresses can induce fibroblast proliferation. On the other hand, the residues arising from the wear of implanted materials in the joints may play an important role in the process of loosening of prostheses - both aseptic and septic. Direct interactions between the released molecule and the macrophage surface are sufficient to activate osteoclastogenic signaling pathways. You cannot ignore allergic reactions to metals used in prostheses in patients undergoing arthroplasty. Demonstration of hypersensitivity to the components of dentures in some cases requires the use of appropriate material in order not to cause an inflammatory allergic reaction. Emerging treatment strategies using mesenchymal stem cells (MSCs) are aimed at improving the initial implant integration and preventing periprosthetic osteolysis. It should be emphasized, however, that the diagnosis of aseptic loosening in many clinical situations raises doubts, because it is at the root of everyone.

Energy-demanding organs like the heart are strongly dependent on oxidative phosphorylation in mitochondria. Oxidative phosphorylation is governed by the respiratory chain located in the inner mitochondrial membrane. The inner mitochondrial membrane is the only cellular membrane with significant amounts of the phospholipid cardiolipin, and cardiolipin was found to directly interact with a number of essential protein complexes, including respiratory chain complexes I to V. An inherited defect in the biogenesis of cardiolipin causes Barth syndrome, which is associated with cardiomyopathy, skeletal myopathy, neutropenia and growth retardation. Energy conversion is dependent on reducing equivalents, which are replenished by oxidative metabolism in the Krebs cycle. Cardiolipin deficiency in Barth syndrome also affects Krebs cycle activity, metabolite transport and mitochondrial morphology. During excitation-contraction coupling, calcium (Ca2+ ) released from the sarcoplasmic reticulum drives sarcomeric contraction. At the same time, Ca2+ influx into mitochondria drives the activation of Krebs cycle dehydrogenases and the regeneration of reducing equivalents. Reducing equivalents are essential not only for energy conversion, but also for maintaining a redox buffer, which is required to detoxify reactive oxygen species (ROS). Defects in CL may also affect Ca2+ uptake into mitochondria and thereby hamper energy supply and demand matching, but also detoxification of ROS. Here, we review the impact of cardiolipin deficiency on mitochondrial function in Barth syndrome and discuss potential therapeutic strategies. This article is protected by copyright. All rights reserved.

The number of deaths from skeletal injuries is still significant, but is declining with advances in emergency medicine. The adopted principles of emergency procedures and the availability of specialist centres enable the treatment to be effective.The aim of the study was to analyse the deaths of patients with spine and limb injuries who required surgery.The analysis covered 22 deaths in the years 2019-2020. The assessment took into account: the cause of admission, the condition of the patient and comorbidities, the medical scales which were used to assess the possible risk of complications, the diagnostic correctness and qualification for surgical treatment, the waiting time for surgery and the cause of death and prior course of action.It can be stated that in 2019, the mortality rate was 0.21 (10 deaths out of 4658 hospitalized), in 2020, the mortality rate was 0.31 (12 deaths out of 3852 hospitalized). The mortality rate in the Department of Traumatic Orthopedics was: 0.30 in 2019 (8 deaths out of 2625 hospitalized) and 0.39 in 2020 (8 deaths in 2020 hospitalized). 10 patients with hip fractures (trochanteric and femoral neck) underwent surgery within 2.7 days (from 1 to 4 days). The causes of death within 1-9 days (average 4.86 days) from admission in this group were complex, and associated with the presence of chronic diseases, including: circulatory failure (9), septic shock (1), heart rhythm disturbances (7), renal failure (6), pulmonary congestion (4), hyperkalemia (1), coagulation disorders (1). In patients after spinal injury with quadriplegia, decompression (1), stabilization (1) and disc removal (1) were performed on the day of admission to the hospital. The patients were hospitalized in the ICU, and deaths occurred on days 9, 15 and 187 from admission due to respiratory and circulatory failure and sudden cardiac arrest. Patients after arthroplasty of the knee (1) and hip (2) were operated on day 2 from admission, and deaths occurred on day 4, 22 and 53 due to: sepsis (1), pulmonary embolism (1), respiratory failure in the course of pneumonia (1).The deceased were admitted in a serious general condition, burdened with numerous concomitant chronic diseases and their age ranged from 66 to 97 years. The surgical treatment was undertaken for life saving reasons but 5 of the deceased did not undergo surgery due to the extreme general condition leading to respiratory and circulatory failure.

Mutations in mitochondrial aminoacyl-tRNA synthetases (mtARSs) have been reported in patients with mitochondriopathies: most commonly encephalopathy, but also cardiomyopathy. Through a GWAS, we showed possible associations between mitochondrial valyl-tRNA synthetase (VARS2) dysregulations and non-ischemic cardiomyopathy. We aimed to investigate the possible consequences of VARS2 depletion in zebrafish and cultured HEK293A cells. Transient VARS2 loss-of-function was induced in zebrafish embryos using Morpholinos. The enzymatic activity of VARS2 was measured in VARS2-depleted cells via northern blot. Heterozygous VARS2 knockout was established in HEK293A cells using CRISPR/Cas9 technology. BN-PAGE and SDS-PAGE were used to investigate electron transport chain (ETC) complexes, and the oxygen consumption rate and extracellular acidification rate were measured using a Seahorse XFe96 Analyzer. The activation of the integrated stress response (ISR) and possible disruptions in mitochondrial fatty acid oxidation (FAO) were explored using RT-qPCR and western blot. Zebrafish embryos with transient VARS2 loss-of-function showed features of heart failure as well as indications of CNS and skeletal muscle involvements. The enzymatic activity of VARS2 was significantly reduced in VARS2-depleted cells. Heterozygous VARS2-knockout cells showed a rearrangement of ETC complexes in favor of complexes III2, III2 + IV, and supercomplexes without significant respiratory chain deficiencies. These cells also showed the enhanced activation of the ISR, as indicated by increased eIF-2α phosphorylation and a significant increase in the transcript levels of ATF4, ATF5, and DDIT3 (CHOP), as well as disruptions in FAO. The activation of the ISR and disruptions in mitochondrial FAO may underlie the adaptive changes in VARS2-depleted cells.

Key points Mitochondrial Ca2+ uptake stimulates the Krebs cycle to regenerate the reduced forms of pyridine nucleotides (NADH, NADPH and FADH2 ) required for ATP production and reactive oxygen species (ROS) elimination. Ca2+ /calmodulin-dependent protein kinase II (CaMKII) has been proposed to regulate mitochondrial Ca2+ uptake via mitochondrial Ca2+ uniporter phosphorylation. We used two mouse models with either global deletion of CaMKIIδ (CaMKIIδ knockout) or cardiomyocyte-specific deletion of CaMKIIδ and γ (CaMKIIδ/γ double knockout) to interrogate whether CaMKII controls mitochondrial Ca2+ uptake in isolated mitochondria and during β-adrenergic stimulation in cardiac myocytes. CaMKIIδ/γ did not control Ca2+ uptake, respiration or ROS emission in isolated cardiac mitochondria, nor in isolated cardiac myocytes, during β-adrenergic stimulation and pacing. The results of the present study do not support a relevant role of CaMKII for mitochondrial Ca2+ uptake in cardiac myocytes under physiological conditions. Abstract Mitochondria are the main source of ATP and reactive oxygen species (ROS) in cardiac myocytes. Furthermore, activation of the mitochondrial permeability transition pore (mPTP) induces programmed cell death. These processes are essentially controlled by Ca2+ , which is taken up into mitochondria via the mitochondrial Ca2+ uniporter (MCU). It was recently proposed that Ca2+ /calmodulin-dependent protein kinase II (CaMKII) regulates Ca2+ uptake by interacting with the MCU, thereby affecting mPTP activation and programmed cell death. In the present study, we investigated the role of CaMKII under physiological conditions in which mitochondrial Ca2+ uptake matches energy supply to the demand of cardiac myocytes. Accordingly, we measured mitochondrial Ca2+ uptake in isolated mitochondria and cardiac myocytes harvested from cardiomyocyte-specific CaMKII δ and γ double knockout (KO) (CaMKIIδ/γ DKO) and global CaMKIIδ KO mice. To simulate a physiological workload increase, cardiac myocytes were subjected to β-adrenergic stimulation (by isoproterenol superfusion) and an increase in stimulation frequency (from 0.5 to 5 Hz). No differences in mitochondrial Ca2+ accumulation were detected in isolated mitochondria or cardiac myocytes from both CaMKII KO models compared to wild-type littermates. Mitochondrial redox state and ROS production were unchanged in CaMKIIδ/γ DKO, whereas we observed a mild oxidation of mitochondrial redox state and an increase in H2 O2 emission from CaMKIIδ KO cardiac myocytes exposed to an increase in workload. In conclusion, the results obtained in the present study do not support the regulation of mitochondrial Ca2+ uptake via the MCU or mPTP activation by CaMKII in cardiac myocytes under physiological conditions.

Excessive production of reactive oxygen species (ROS) is characteristic of numerous diseases, but most studies in this area have not considered the impact of endogenous antioxidative defenses. Here, utilizing multi-omics, we demonstrate that in cardiomyocytes mitochondrial isocitrate dehydrogenase (IDH2) constitutes a major antioxidant defense. In both male and female mice and humans the paradoxical reduction in expression of IDH2 associated with heart failure is compensated for by an increase in the enzyme’s activity. We describe extensive mutual regulation of the antioxidant activities of IDH2 and NRF2 by a network involving 2-oxoglutarate and L2-hydroxyglutarate and mediated in part through unconventional hydroxymethylation of cytosine residues present in introns. Conditional targeting of ROS in a murine model of heart failure improves cardiac function. Together, these insights may explain why previous attempts to treat heart failure with antioxidants have been unsuccessful and open new approaches to personalizing and, thereby, improving such treatment.Graphical abstractHighlightsParadoxical downregulation of mitochondrial isocitrate dehydrogenase (IDH2) in response to oxidative stress leads to the discovery of a robust antioxidative defense in the heart.An antioxidative loop involving IDH2 coordinates other antioxidative defenses, such as NRF2.This loop produces epigenetic modifications that link oxidative stress to mitochondrial function.The conclusion that enhancing antioxidative capacity improves cardiac function only when the endogenous capacity is insufficient opens new approaches to individualized treatment of patients with heart failure.

Barth syndrome (BTHS) is caused by mutations of the gene encoding tafazzin, which catalyzes maturation of mitochondrial cardiolipin and often manifests with systolic dysfunction during early infancy. Beyond the first months of life, BTHS cardiomyopathy typically transitions to a phenotype of diastolic dysfunction with preserved ejection fraction, blunted contractile reserve during exercise, and arrhythmic vulnerability. Previous studies traced BTHS cardiomyopathy to mitochondrial formation of reactive oxygen species (ROS). Because mitochondrial function and ROS formation are regulated by excitation-contraction coupling, integrated analysis of mechano-energetic coupling is required to delineate the pathomechanisms of BTHS cardiomyopathy.We analyzed cardiac function and structure in a mouse model with global knockdown of tafazzin (Downregulation of mitochondrial Ca

Myocardial infarction (MI) is one of the major contributors to cardiovascular morbidity and mortality. Excess inflammation significantly contributes to cardiac remodeling and heart failure after MI. Accumulating evidence has shown the central role of cellular metabolism in regulating the differentiation and function of cells. Metabolic rewiring is particularly relevant for proinflammatory responses induced by ischemia. Hypoxia reduces mitochondrial oxidative phosphorylation (OXPHOS) and induces increased reliance on glycolysis. Moreover, activation of a proinflammatory transcriptional program is associated with preferential glucose metabolism in leukocytes. An improved understanding of the mechanisms that regulate metabolic adaptations holds the potential to identify new metabolic targets and strategies to reduce ischemic cardiac damage, attenuate excess local inflammation and ultimately prevent the development of heart failure. Among possible drug targets, glucose transporter 1 (GLUT1) gained considerable interest considering its pivotal role in regulating glucose availability in activated leukocytes and the availability of small molecules that selectively inhibit it. Therefore, we summarize current evidence on the role of GLUT1 in leukocytes (focusing on macrophages and T cells) and non-leukocytes, including cardiomyocytes, endothelial cells and fibroblasts regarding ischemic heart disease. Beyond myocardial infarction, we can foresee the role of GLUT1 blockers as a possible pharmacological approach to limit pathogenic inflammation in other conditions driven by excess sterile inflammation.

Significance: Cardiovascular stem cells are important for regeneration and repair of damaged tissue. Recent Advances: Pluripotent stem cells have a unique metabolism, which is adopted for their ene...

The interplay between the cardiovascular system, metabolism, and inflammation plays a central role in the pathophysiology of a wide spectrum of cardiovascular diseases, including heart failure. Here, we provide an overview of the fundamental aspects of the interrelation between inflammation and metabolism, ranging from the role of metabolism in immune cell function to the processes how inflammation modulates systemic and cardiac metabolism. Furthermore, we discuss how disruption of this immuno-metabolic interface is involved in the development and progression of cardiovascular disease, with a special focus on heart failure. Finally, we present new technologies and therapeutic approaches that have recently emerged and hold promise for the future of cardiovascular medicine.

Barth syndrome (BTHS) is an inherited form of cardiomyopathy, caused by a mutation within the gene encoding the mitochondrial transacylase tafazzin. Tafazzin is involved in the biosynthesis of the unique phospholipid cardiolipin (CL), which is almost exclusively found in mitochondrial membranes. CL directly interacts with a number of essential protein complexes in the mitochondrial membranes including the respiratory chain, mitochondrial metabolite carriers, and proteins, involved in shaping mitochondrial morphology. Here we describe, how in BTHS CL deficiency causes changes in the morphology of mitochondria, structural changes in the respiratory chain, decreased respiration, and increased generation of reactive oxygen species. A large number of cellular and animal models for BTHS have been established to elucidate how mitochondrial dysfunction induces sarcomere disorganization and reduced contractility, resulting in dilated cardiomyopathy in vivo.

The E3 ubiquitin ligase PARK2 and the mitochondrial protein kinase PINK1 are required for the initiation of mitochondrial damage-induced mitophagy. Together, PARK2 and PINK1 generate a phospho-ubiquitin signal on outer mitochondrial membrane proteins that triggers recruitment of the autophagy machinery. This paper describes the detection of a defined 500-kDa phospho-ubiquitin-rich PARK2 complex that accumulates on mitochondria upon treatment with the membrane uncoupler CCCP. Formation of this complex is dependent on the presence of PINK1 and is absent in mutant forms of PARK2, whereby mitophagy is also arrested. These results signify a functional signaling complex that is essential for the progression of mitophagy. The visualization of the PARK2 signaling complex represents a novel marker for this critical step in mitophagy and can be used to monitor mitophagy progression in PARK2 mutants and to uncover additional upstream factors required for PARK2-mediated mitophagy signaling.

Mitochondria play a prominent role in cardiac energy metabolism, and their function is critically dependent on the integrity of mitochondrial membranes. Disorders characterized by mitochondrial dysfunction are commonly associated with cardiac disease. The mitochondrial phospholipid cardiolipin directly interacts with a number of essential protein complexes in the mitochondrial membranes including the respiratory chain, mitochondrial metabolite carriers, and proteins critical for mitochondrial morphology. Barth syndrome is an X-linked disorder caused by an inherited defect in the biogenesis of the mitochondrial phospholipid cardiolipin. How cardiolipin deficiency impacts on mitochondrial function and how mitochondrial dysfunction causes cardiomyopathy has been intensively studied in cellular and animal models of Barth syndrome. These findings may also have implications for the molecular mechanisms underlying other inherited disorders associated with defects in cardiolipin, such as Sengers syndrome and dilated cardiomyopathy with ataxia (DCMA).

This paper gives the extensive overview about the Arc Flash Risk Assessment (AFRA) procedures and methodologies used in US and in EU environment. For both regions, the overview of related standards and guides is given. The main part of this paper describes the complete AFRA scope including arc flash risk identification, risk assessment (calculation) and risk control (mitigation). The AFRA flow chart is introduced to graphically present entire AFRA lifecycle with three possible approaches for AFRA execution (at present).

The Stoffella surgical method is a reverse Chevron distal metatarsal osteotomy, typically used in younger patients, with good bone quality. The technique is suitable for a variety of cases, from mild to severe, since the head of the first metatarsal may be moved laterally to the edge of the first metatarsal bone, thereby allowing for a significant degree of correction.The aim of the paper is to review the radiological results of patients suffering from hallux valgus who underwent Stoffella metatarsal I osteotomy.The study has been carried out using a sample of 23 patients, evaluating their pre and post-surgery radiographs. It seeks to examine the effectiveness of the Stoffella metatarsal I osteotomy by measurements of the HVA (Hallux Valgus Angle), IMA (Intermetatarsal Angle), DMAA (Distal Metaphyseal Articular Angle) both prior to and post-surgical correction.The study demonstrated that the Stoffella Metatarsal I osteotomy has a high rate of success, with correction of the HVA, IMA, DMAA angles, with pre- surgery HVA being 29.7°±6.1°, IMA - 12.9°±3.6°, DMAA - 13.7°±7.1°, Post-surgery results show a mean reduction of 51.28%, 51.13%, 50.56% respectively towards a mean HVA of 14.5°±7.4° (p0.001), mean IMA of 6.3°±3.7° (p0.001), mean DMAA of 6.8°±4° (p0.001). All patients who underwent the surgery had HVA, IMA, DMAA angles within the normal physiological range post-surgery.It was concluded that the Stoffella Metatarsal I osteotomy is effective in the correction of the hallux valgus.

Mitochondria have originated in eukaryotic cells by endosymbiosis of a specialized prokaryote approximately 2 billion years ago. They are essential for normal cell function by providing energy through their role in oxidizing carbon substrates. Glutathione (GSH) is a major thiol-disulfide redox buffer of the cell including the mitochondrial matrix and intermembrane space. We have generated cardiomyocyte-specific Grx1-roGFP2 GSH redox potential (EGSH) biosensor mice in the past, in which the sensor is targeted to the mitochondrial matrix. Using this mouse model a distinct EGSH of the mitochondrial matrix (−278.9 ± 0.4 mV) in isolated cardiomyocytes is observed. When analyzing the EGSH in isolated mitochondria from the transgenic hearts, however, the EGSH in the mitochondrial matrix is significantly oxidized (−247.7 ± 8.7 mV). This is prevented by adding N-Ethylmaleimide during the mitochondria isolation procedure, which precludes disulfide bond formation. A similar reducing effect is observed by isolating mitochondria in hypoxic (0.1–3% O2) conditions that mimics mitochondrial pO2 levels in cellulo. The reduced EGSH is accompanied by lower ROS production, reduced complex III activity but increased ATP levels produced at baseline and after stimulation with succinate/ADP. Altogether, we demonstrate that oxygenation is an essential factor that needs to be considered when analyzing mitochondrial function ex vivo., Highlights • We identified that mitochondria isolated in room air at 20.9% O2 exhibit a strong oxidation of the EGSH in the matrix. • Isolation of mitochondria in hypoxic conditions mimicking their in cellulo conditions prevents oxidation of the EGSH. • Normoxic and hypoxic isolated mitochondria differ in ROS production, complex III activity and ATP levels. • Oxygenation needs to be considered when analyzing mitochondrial function ex vivo.

Reactive oxygen species (ROS) are emerging as important regulators of cancer growth and metastatic spread. However, how cells integrate redox signals to affect cancer progression is not fully understood. Mitochondria are cellular redox hubs, which are highly regulated by interactions with neighboring organelles. Here, we investigated how ROS at the endoplasmic reticulum (ER)-mitochondria interface are generated and translated to affect melanoma outcome. We show that TMX1 and TMX3 oxidoreductases, which promote ER-mitochondria communication, are upregulated in melanoma cells and patient samples. TMX knockdown altered mitochondrial organization, enhanced bioenergetics, and elevated mitochondrial- and NOX4-derived ROS. The TMX-knockdown-induced oxidative stress suppressed melanoma proliferation, migration, and xenograft tumor growth by inhibiting NFAT1. Furthermore, we identified NFAT1-positive and NFAT1-negative melanoma subgroups, wherein NFAT1 expression correlates with melanoma stage and metastatic potential. Integrative bioinformatics revealed that genes coding for mitochondrial- and redox-related proteins are under NFAT1 control and indicated that TMX1, TMX3, and NFAT1 are associated with poor disease outcome. Our study unravels a novel redox-controlled ER-mitochondria-NFAT1 signaling loop that regulates melanoma pathobiology and provides biomarkers indicative of aggressive disease. peerReviewed

The normal function of the heart relies on a series of complex metabolic processes orchestrating the proper generation and use of energy. In this context, mitochondria serve a crucial role as a platform for energy transduction by supplying ATP to the varying demand of cardiomyocytes, involving an intricate network of pathways regulating the metabolic flux of substrates. The failure of these processes results in structural and functional deficiencies of the cardiac muscle, including inherited cardiomyopathies. These genetic diseases are characterized by cardiac structural and functional anomalies in the absence of abnormal conditions that can explain the observed myocardial abnormality, and are frequently associated with heart failure. Since their original description, major advances have been achieved in the genetic and phenotype knowledge, highlighting the involvement of metabolic abnormalities in their pathogenesis. This review provides a brief overview of the role of mitochondria in the energy metabolism in the heart and focuses on metabolic abnormalities, mitochondrial dysfunction, and storage diseases associated with inherited cardiomyopathies.

Mitochondrial CaMitochondria are the main source of ATP and reactive oxygen species (ROS) in cardiac myocytes. Furthermore, activation of the mitochondrial permeability transition pore (mPTP) induces programmed cell death. These processes are essentially controlled by Ca

Rett syndrome (RTT), an X chromosome-linked neurodevelopmental disorder affecting almost exclusively females, is associated with various mitochondrial alterations. Mitochondria are swollen, show altered respiratory rates, and their inner membrane is leaking protons. To advance the understanding of these disturbances and clarify their link to redox impairment and oxidative stress, we assessed mitochondrial respiration in defined brain regions and cardiac tissue of male wildtype (WT) and MeCP2-deficient (Mecp2-/y) mice. Also, we quantified for the first time neuronal redox-balance with subcellular resolution in cytosol and mitochondrial matrix. Quantitative roGFP1 redox imaging revealed more oxidized conditions in the cytosol of Mecp2-/y hippocampal neurons than in WT neurons. Furthermore, cytosol and mitochondria of Mecp2-/y neurons showed exaggerated redox-responses to hypoxia and cell-endogenous reactive oxygen species (ROS) formation. Biochemical analyzes exclude disease-related increases in mitochondrial mass in Mecp2-/y hippocampus and cortex. Protein levels of complex I core constituents were slightly lower in Mecp2-/y hippocampus and cortex than in WT; those of complex V were lower in Mecp2-/y cortex. Respiratory supercomplex-formation did not differ among genotypes. Yet, supplied with the complex II substrate succinate, mitochondria of Mecp2-/y cortex and hippocampus consumed more O2 than WT. Furthermore, mitochondria from Mecp2-/y hippocampus and cortex mediated an enhanced oxidative burden. In conclusion, we further advanced the molecular understanding of mitochondrial dysfunction in RTT. Intensified mitochondrial O2 consumption, increased mitochondrial ROS generation and disturbed redox balance in mitochondria and cytosol may represent a causal chain, which provokes dysregulated proteins, oxidative tissue damage, and contributes to neuronal network dysfunction in RTT.

Mitochondria play an essential role in the energy metabolism of the heart. Many of the essential functions are associated with mitochondrial membranes and oxidative phosphorylation driven by the respiratory chain. Mitochondrial membranes are unique in the cell as they contain the phospholipid cardiolipin. The important role of cardiolipin in cardiovascular health is highlighted by several cardiac diseases, in which cardiolipin plays a fundamental role. Barth syndrome, Sengers syndrome, and Dilated cardiomyopathy with ataxia (DCMA) are genetic disorders, which affect cardiolipin biosynthesis. Other cardiovascular diseases including ischemia/reperfusion injury and heart failure are also associated with changes in the cardiolipin pool. Here, we summarize molecular functions of cardiolipin in mitochondrial biogenesis and morphology. We highlight the role of cardiolipin for the respiratory chain, metabolite carriers, and mitochondrial metabolism and describe links to apoptosis and mitochondria specific autophagy (mitophagy) with possible implications in cardiac disease.

The three mitochondrial-encoded proteins, COX1, COX2, and COX3, form the core of the cytochrome c oxidase. Upon synthesis, COX2 engages with COX20 in the inner mitochondrial membrane, a scaffold protein that recruits metallochaperones for copper delivery to the CuA-Site of COX2. Here we identified the human protein, TMEM177 as a constituent of the COX20 interaction network. Loss or increase in the amount of TMEM177 affects COX20 abundance leading to reduced or increased COX20 levels respectively. TMEM177 associates with newly synthesized COX2 and SCO2 in a COX20-dependent manner. Our data shows that by unbalancing the amount of TMEM177, newly synthesized COX2 accumulates in a COX20-associated state. We conclude that TMEM177 promotes assembly of COX2 at the level of CuA-site formation., Highlights • TMEM177 is a mitochondrial inner membrane protein. • COX20 associates with TMEM177. • The TMEM177 protein forms a complex with COX2 and copper chaperones.

This paper describes the Failure Mode and Effects Analysis (FMEA) focusing on tertiary side of (E)HV/HV/MV transformers and MV self-consumption subsystem of the Czech transmission power system. The goal of this FMEA is a) to identify all possible failure modes, which can occur in the examined system; b) to determine the impact of each failure mode on upstream (E)HV/HV system (referred to as FMEA I.) and on MV self-consumption subsystem (referred to as FMEA II.); c) to evaluate the severity and frequency of each failure mode; and d) to propose suitable actions for mitigation or complete elimination of these failure modes and their impacts.

This reason to carry out this investigation was a complaint from international airport about increased maintenance cost and insufficient reliability of runway lighting systems. The exhaustive investigation of overall lighting installation was carried out, which comprises lighting parameters, mechanical parameters and electrical parameters. The possible causes of luminous flux drop and significantly lowered mean time between failures have been explained. These causes were presented as observed mechanical and electrical changes of incandescent lamp filaments, for current source power supply, which is utilized in runway lighting system.

Electric drainage is used to protect devices which are buried underground (such as piping) from the negative effects of DC electric traction induced stray currents. In places where stray currents leave the underground device and return into rails, they contribute to the corrosion of buried devices. Electric drainage is one of the possibilities to minimise these negative effects. Electric drainage is a conductive connection between the buried device and electric traction rails, which ensures that current does not flow from the device into the ground, but it flows through this connection instead. Currently, the most widely used type is regulated electric drainage. In most cases, current is regulated by pulse width modulation (PWM). When this modulation is used, the current flowing through the drainage contains harmonic components with different frequencies. Track circuits are often used on railways, as an important part of the track security system. For secure operation, it is necessary to make sure that frequencies generated by the drainage do not interfere with track circuits. This paper deals with the design of a regulated drainage control system, with regard to its compatibility with track circuits. The paper contains results of computer simulation, as well as those of on-site measurements carried out on a prototype installed on a tram track.

Within the research activities, the realization team did the complete development of the annealing unit with the aid of modern technology and components, such as the programmable logic controller, industrial PC, and microcontrollers, to secure an intelligent way of switching the power semiconductor switches (SSR relays) with regard to minimizing the low frequency conducted disturbances. The annealing unit has the implemented algorithm for two ways of output power control, i.e. phase control and full wave control. The algorithm of the full wave control is designed in a way so as to arrange the balanced power in the load. By using this way of control, the harmonic emission is almost entirely eliminated, but the influence of the flicker effect will surface. The article offers a complex view at the annealing unit from the control method perspective, ensuring the correct annealing cycle and subsequent influence of the annealing unit to supply network. It deals deeply with EMC analysis for both ways of designed annealing unit control. The analysis comes out from the experimental measurements on the functional annealing unit prototype.DOI: http://dx.doi.org/10.5755/j01.eie.23.5.19239

The prolyl-4-hydroxylase domain (PHD) enzymes are regarded as the molecular oxygen sensors. There is an interplay between oxygen availability and cellular metabolism, which in turn has significant effects on the functionality of innate immune cells, such as macrophages. However, if and how PHD enzymes affect macrophage metabolism are enigmatic. We hypothesized that macrophage metabolism and function can be controlled via manipulation of PHD2. We characterized the metabolic phenotypes of PHD2-deficient RAW cells and primary PHD2 knockout bone marrow-derived macrophages (BMDM). Both showed typical features of anaerobic glycolysis, which were paralleled by increased pyruvate dehydrogenase kinase 1 (PDK1) protein levels and a decreased pyruvate dehydrogenase enzyme activity. Metabolic alterations were associated with an impaired cellular functionality. Inhibition of PDK1 or knockout of hypoxia-inducible factor 1 alpha (HIF-1 alpha) reversed the metabolic phenotype and impaired the functionality of the PHD2-deficient RAW cells and BMDM. Taking these results together, we identified a critical role of PHD2 for a reversible glycolytic reprogramming in macrophages with a direct impact on their function. We suggest that PHD2 serves as an adjustable switch to control macropha(g)e behavior.

Mitochondria are turned over by an autophagic process termed mitophagy. This process is considered to remove damaged, superfluous and aged organelles. However, little is known about how defective organelles are recognized, what types of damage induce turnover, and whether an identical set of factors contributes to degradation under different conditions. Here we systematically compared the mitophagy rate and requirement for mitophagy-specific proteins during post-log-phase and rapamycin-induced mitophagy. To specifically assess mitophagy of damaged mitochondria, we analyzed cells accumulating proteins prone to degradation due to lack of the mitochondrial AAA-protease Yme1. While autophagy 32 (Atg32) was required under all tested conditions, the function of Atg33 could be partially bypassed in post-log-phase and rapamycin-induced mitophagy. Unexpectedly, we found that Uth1 was dispensable for mitophagy. A re-evaluation of its mitochondrial localization revealed that Uth1 is a protein of the inner mitochondrial membrane that is targeted by a cleavable N-terminal pre-sequence. In agreement with our functional analyses, this finding excludes a role of Uth1 as a mitochondrial surface receptor.

Most mitochondrial proteins are encoded in the nucleus. They are synthesized as precursor forms in the cytosol and must be imported into mitochondria with the help of different protein translocases. Distinct import signals within precursors direct each protein to the mitochondrial surface and subsequently onto specific transport routes to its final destination within these organelles. In this review we highlight common principles of mitochondrial protein import and address different mechanisms of protein integration into mitochondrial membranes. Over the last years it has become clear that mitochondrial protein translocases are not independently operating units, but in fact closely cooperate with each other. We discuss recent studies that indicate how the pathways for mitochondrial protein biogenesis are embedded into a functional network of various other physiological processes, such as energy metabolism, signal transduction, and maintenance of mitochondrial morphology. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.

Barth syndrome (BTHS) patients carrying mutations in tafazzin (TAZ1), which is involved in the final maturation of cardiolipin, present with dilated cardiomyopathy, skeletal myopathy, growth retardation and neutropenia. To study how mitochondrial function is impaired in BTHS patients, we generated induced pluripotent stem cells (iPSCs) to develop a novel and relevant human model system for BTHS. BTHS-iPSCs generated from dermal fibroblasts of three patients with different mutations in TAZ1 expressed pluripotency markers, and were able to differentiate into cells derived from all three germ layers both in vitro and in vivo. We used these cells to study the impact of tafazzin deficiency on mitochondria( oxidative phosphorylation. We found an impaired remodeling of cardiolipin, a dramatic decrease in basal oxygen consumption rate and in the maximal respiratory capacity in BTHS-iPSCs. Simultaneous measurement of extra-cellular acidification rate allowed us a thorough assessment of the metabolic deficiency in BTHS patients. Blue native gel analyses revealed that decreased respiration coincided with dramatic structural changes in respiratory chain supercomplexes leading to a massive increase in generation of reactive oxygen species. Our data demonstrate that BTHS-iPSCs are capable of modeling BTHS by recapitulating the disease phenotype and thus are important tools for studying the disease mechanism. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.