Mitochondrial ATP synthase: architecture, function and pathology

Dynamic human liver proteome atlas reveals functional insights into disease pathways

Deeper understanding of liver pathophysiology would benefit from a comprehensive quantitative proteome resource at cell type resolution to predict outcome and design therapy. Here, we quantify more than 150,000 sequence‐unique peptides aggregated into 10,000 proteins across total liver, the major liver cell types, time course of primary cell cultures, and liver disease states. Bioinformatic analysis reveals that half of hepatocyte protein mass is comprised of enzymes and 23% of mitochondrial proteins, twice the proportion of other liver cell types. Using primary cell cultures, we capture dynamic proteome remodeling from tissue states to cell line states, providing useful information for biological or pharmaceutical research. Our extensive data serve as spectral library to characterize a human cohort of non‐alcoholic steatohepatitis and cirrhosis. Dramatic proteome changes in liver tissue include signatures of hepatic stellate cell activation resembling liver cirrhosis and providing functional insights. We built a web‐based dashboard application for the interactive exploration of our resource (www.liverproteome.org).

Inhibition of Escherichia coli ATP synthase and cell growth by dietary pomegranate phenolics

Historically, people have been using pomegranate to alleviate many disease conditions. Pomegranate is known for its antiinflammatory, antioxidant, neuroprotective, anticancer, and antibacterial properties. In the current study, we examined effects of 8 dietary phenolics present in pomegranate (DPPs)-cyanidin-3-glucoside, cyanin chloride, delphinidin-3-glucoside, delphinidin-3,5-diglucoside, pelargonidin-3-glucoside, pelargonin chloride, punicalagin, and punicalin-on Escherichia coli ATP synthase and cell growth. DPPs caused complete or near complete (89%-100%) inhibition of wild-type E. coli ATP synthase and partial (5%-64%) inhibition of mutant enzymes αR283D, αE284R, βV265Q, and γT273A. Growth inhibition of wild-type, null, and mutant strains in the presence of DPPs were lower than that of isolated wild-type and mutant ATP synthase. On a molar scale, cyanin chloride was the most potent, and pelargonidin-3-glucoside was the least effective inhibitor of wild-type ATP synthase. Partial inhibition of mutant enzymes confirmed that αR283D, αE284R, βV265Q, and γT273A are essential in the formation of the phytochemical binding site. Our results establish that DPPs are potent inhibitors of wild-type E. coli ATP synthase and that the antimicrobial nature of DPPs can be associated with the binding and inhibition of microbial ATP synthase. Additionally, selective inhibition of microbial ATP synthase by DPPs is a useful method to combat antimicrobial resistance.

Effects of Anticancer Agent P-bi-TAT on Gene Expression Link the Integrin Thyroid Hormone Receptor to Expression of Stemness and Energy Metabolism Genes in Cancer Cells

Chemically modified forms of tetraiodothyroacetic acid (tetrac), an L-thyroxine derivative, have been shown to exert their anticancer activity at plasma membrane integrin αvβ3 of tumor cells. Via a specific hormone receptor on the integrin, tetrac-based therapeutic agents modulate expression of genes relevant to cancer cell proliferation, survival and energy metabolism. P-bi-TAT, a novel bivalent tetrac-containing synthetic compound has anticancer activity in vitro and in vivo against glioblastoma multiforme (GBM) and other types of human cancers. In the current study, microarray analysis was carried out on a primary culture of human GBM cells exposed to P-bi-TAT (10⁻⁶ tetrac equivalent) for 24 h. P-bi-TAT significantly affected expression of a large panel of genes implicated in cancer cell stemness, growth, survival and angiogenesis. Recent interest elsewhere in ATP synthase as a target in GBM cells caused us to focus attention on expression of genes involved in energy metabolism. Significantly downregulated transcripts included multiple energy-metabolism-related genes: electron transport chain genes ATP5A1 (ATP synthase 1), ATP51, ATP5G2, COX6B1 (cytochrome c oxidase subunit 6B1), NDUFA8 (NADH dehydrogenase (ubiquinone) FA8), NDUFV2I and other NDUF genes. The NDUF and ATP genes are also relevant to control of oxidative phosphorylation and transcription. Qualitatively similar actions of P-bi-TAT on expression of subsets of energy-metabolism-linked genes were also detected in established human GBM and pancreatic cancer cell lines. In conclusion, acting at αvβ3 integrin, P-bi-TAT caused downregulation in human cancer cells of expression of a large number of genes involved in electron transport and oxidative phosphorylation. These observations suggest that cell surface thyroid hormone receptors on αvβ3 regulate expression of genes relevant to tumor cell stemness and energy metabolism.

Prescription Drugs and Mitochondrial Metabolism

Mitochondria are central to the physiology and survival of nearly all eukaryotic cells and house diverse metabolic processes including oxidative phosphorylation, reactive oxygen species buffering, metabolite synthesis/exchange, and Ca2+ sequestration. Mitochondria are phenotypically heterogeneous and this variation is essential to the complexity of physiological function among cells, tissues, and organ systems. As a consequence of mitochondrial integration with so many physiological processes, small molecules that modulate mitochondrial metabolism induce complex systemic effects. In the case of many common prescribed drugs, these interactions may contribute to drug therapeutic mechanisms, induce adverse drug reactions, or both. The purpose of this article is to review historical and recent advances in the understanding of the effects of prescription drugs on mitochondrial metabolism. Specific 'modes' of xenobiotic-mitochondria interactions are discussed to provide a set of qualitative models that aid in conceptualizing how the mitochondrial energy transduction system may be affected. Findings of recent in vitro high-throughput screening studies are reviewed, and a few candidate drug classes are chosen for additional brief discussion (i.e. antihyperglycemics, antidepressants, antibiotics, and antihyperlipidemics). Finally, recent improvements in pharmacokinetic models that aid in quantifying systemic effects of drug-mitochondria interactions are briefly considered.

Applying Sodium Carbonate Extraction Mass Spectrometry to Investigate Defects in the Mitochondrial Respiratory Chain

Mitochondria are complex organelles containing 13 proteins encoded by mitochondrial DNA and over 1,000 proteins encoded on nuclear DNA. Many mitochondrial proteins are associated with the inner or outer mitochondrial membranes, either peripherally or as integral membrane proteins, while others reside in either of the two soluble mitochondrial compartments, the mitochondrial matrix and the intermembrane space. The biogenesis of the five complexes of the oxidative phosphorylation system are exemplars of this complexity. These large multi-subunit complexes are comprised of more than 80 proteins with both membrane integral and peripheral associations and require soluble, membrane integral and peripherally associated assembly factor proteins for their biogenesis. Mutations causing human mitochondrial disease can lead to defective complex assembly due to the loss or altered function of the affected protein and subsequent destabilization of its interactors. Here we couple sodium carbonate extraction with quantitative mass spectrometry (SCE-MS) to track changes in the membrane association of the mitochondrial proteome across multiple human knockout cell lines. In addition to identifying the membrane association status of over 840 human mitochondrial proteins, we show how SCE-MS can be used to understand the impacts of defective complex assembly on protein solubility, giving insights into how specific subunits and sub-complexes become destabilized.

Next-generation sequencing of the whole mitochondrial genome identifies functionally deleterious mutations in patients with multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated disease of the central nervous system with genetics and environmental determinants. Studies focused on the neurogenetics of MS showed that mitochondrial DNA (mtDNA) mutations that can ultimately lead to mitochondrial dysfunction, alter brain energy metabolism and cause neurodegeneration. We analyzed the whole mitochondrial genome using next-generation sequencing (NGS) from 47 Saudi individuals, 23 patients with relapsing-remitting MS and 24 healthy controls to identify mtDNA disease-related mutations/variants. A large number of variants were detected in the D-loop and coding genes of mtDNA. While distinct unique variants were only present in patients or only occur in controls, a number of common variants were shared among the two groups. The prevalence of some common variants differed significantly between patients and controls, thus could be implicated in susceptibility to MS. Of the unique variants only present in the patients, 34 were missense mutations, located in different mtDNA-encoded genes. Seven of these mutations were not previously reported in MS, and predicted to be deleterious with considerable impacts on the functions and structures of encoded-proteins and may play a role in the pathogenesis of MS. These include two heteroplasmic mutations namely 10237T>C in MT-ND3 gene and 15884G>C in MT-CYB gene; and three homoplasmic mutations namely 9288A>G in MT-CO3 gene, 14484T>C in MT-ND6 gene, 15431G>A in MT-CYB gene, 8490T>C in MT-ATP8 gene and 5437C>T in MT-ND2 gene. Notably some patients harboured multiple mutations while other patients carried the same mutations. This study is the first to sequence the entire mitochondrial genome in MS patients in an Arab population. Our results expanded the mutational spectrum of mtDNA variants in MS and highlighted the efficiency of NGS in population-specific mtDNA variant discovery. Further investigations in a larger cohort are warranted to confirm the role of mtDNA MS.

Mitochondrial Determinants of Anti-Cancer Drug-Induced Cardiotoxicity

Mitochondria are key organelles for the maintenance of myocardial tissue homeostasis, playing a pivotal role in adenosine triphosphate (ATP) production, calcium signaling, redox homeostasis, and thermogenesis, as well as in the regulation of crucial pathways involved in cell survival. On this basis, it is not surprising that structural and functional impairments of mitochondria can lead to contractile dysfunction, and have been widely implicated in the onset of diverse cardiovascular diseases, including ischemic cardiomyopathy, heart failure, and stroke. Several studies support mitochondrial targets as major determinants of the cardiotoxic effects triggered by an increasing number of chemotherapeutic agents used for both solid and hematological tumors. Mitochondrial toxicity induced by such anticancer therapeutics is due to different mechanisms, generally altering the mitochondrial respiratory chain, energy production, and mitochondrial dynamics, or inducing mitochondrial oxidative/nitrative stress, eventually culminating in cell death. The present review summarizes key mitochondrial processes mediating the cardiotoxic effects of anti-neoplastic drugs, with a specific focus on anthracyclines (ANTs), receptor tyrosine kinase inhibitors (RTKIs) and proteasome inhibitors (PIs).

Profiling the Skeletal Muscle Proteome in Patients on Atypical Antipsychotics and Mood Stabilizers

Atypical antipsychotics (AAP) are used in the treatment of severe mental illness. They are associated with several metabolic side effects including insulin resistance. The skeletal muscle is the primary tissue responsible for insulin-stimulated glucose uptake. Dysfunction of protein regulation within the skeletal muscle following treatment with AAPs may play a role in the associated metabolic side effects. The objective of this study was to measure protein abundance in the skeletal muscle of patients on long-term AAP or mood stabilizer treatment. Cross-sectional muscle biopsies were obtained from patients with bipolar disorder and global protein abundance was measured using stable isotope labeling by amino acid (SILAC) combined with high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Sixteen patients completed muscle biopsies and were included in the proteomic analyses. A total of 40 proteins were significantly different between the AAP group and the mood stabilizer group. In-silico pathway analysis identified significant enrichment in several pathways including glucose metabolism, cell cycle, apoptosis, and folate metabolism. Proteome abundance changes also differed based on protein biological processes and function. In summary, significant differences in proteomic profiles were identified in the skeletal muscle between patients on AAPs and mood stabilizers. Future work is needed to validate these findings in prospectively sampled populations.

Variants in Mitochondrial ATP Synthase Cause Variable Neurologic Phenotypes

OBJECTIVE

ATP synthase (ATPase) is responsible for the majority of ATP production. Nevertheless, disease phenotypes associated with mutations in ATPase subunits are extremely rare. We aimed at expanding the spectrum of ATPase-related diseases.

METHODS

Whole-exome sequencing in cohorts with 2,962 patients diagnosed with mitochondrial disease and/or dystonia and international collaboration were used to identify deleterious variants in ATPase-encoding genes. Findings were complemented by transcriptional and proteomic profiling of patient fibroblasts. ATPase integrity and activity were assayed using cells and tissues from 5 patients.

RESULTS

We present 10 total individuals with biallelic or de novo monoallelic variants in nuclear ATPase subunit genes. Three unrelated patients showed the same homozygous missense ATP5F1E mutation (including one published case). An intronic splice-disrupting alteration in compound heterozygosity with a nonsense variant in ATP5PO was found in one patient. Three patients had de novo heterozygous missense variants in ATP5F1A, whereas another 3 were heterozygous for ATP5MC3 de novo missense changes. Bioinformatics methods and populational data supported the variants' pathogenicity. Immunohistochemistry, proteomics, and/or immunoblotting revealed significantly reduced ATPase amounts in association to ATP5F1E and ATP5PO mutations. Diminished activity and/or defective assembly of ATPase was demonstrated by enzymatic assays and/or immunoblotting in patient samples bearing ATP5F1A-p.Arg207His, ATP5MC3-p.Gly79Val, and ATP5MC3-p.Asn106Lys. The associated clinical profiles were heterogeneous, ranging from hypotonia with spontaneous resolution (1/10) to epilepsy with early death (1/10) or variable persistent abnormalities, including movement disorders, developmental delay, intellectual disability, hyperlactatemia, and other neurologic and systemic features. Although potentially reflecting an ascertainment bias, dystonia was common (7/10).

INTERPRETATION

Our results establish evidence for a previously unrecognized role of ATPase nuclear-gene defects in phenotypes characterized by neurodevelopmental and neurodegenerative features. ANN NEUROL 2022;91:225-237.

Clinical Heterogeneity in MT-ATP6 Pathogenic Variants: Same Genotype-Different Onset

Human mitochondrial disease exhibits large variation of clinical phenotypes, even in patients with the same causative gene defect. We illustrate this heterogeneity by confronting clinical and biochemical data of two patients with the uncommon pathogenic homoplasmic NC_012920.1(MT-ATP6):m.9035T>C variant in MT-ATP6. Patient 1 presented as a toddler with severe motor and speech delay and spastic ataxia without extra-neurologic involvement. Patient 2 presented in adolescence with ataxia and ophthalmoplegia without cognitive or motor impairment. Respiratory chain complex activities were normal in cultured skin fibroblasts from both patients when calculated as ratios over citrate synthase activity. Native gels found presence of subcomplexes of complex V in fibroblast and/or skeletal muscle. Bioenergetic measurements in fibroblasts from both patients detected reduced spare respiratory capacities and altered extracellular acidification rates, revealing a switch from mitochondrial respiration to glycolysis to uphold ATP production. Thus, in contrast to the differing disease presentation, biochemical evidence of mitochondrial deficiency turned out quite similar. We conclude that biochemical analysis remains a valuable tool to confirm the genetic diagnosis of mitochondrial disease, especially in patients with new gene variants or atypical clinical presentation.

Identification and validation of a signature involving voltage-gated chloride ion channel genes for prediction of prostate cancer recurrence

Voltage-gated chloride ion channels (CLCs) are transmembrane proteins that maintain chloride ion homeostasis in various cells. Accumulating studies indicated CLCs were related to cell growth, proliferation, and cell cycle. Nevertheless, the role of CLCs in prostate cancer (PCa) has not been systematically profiled. The purpose of this study was to investigate the expression profiles and biofunctions of CLCs genes, and construct a novel risk signature to predict biochemical recurrence (BCR) of PCa patients. We identified five differentially expressed CLCs genes in our cohort and then constructed a signature composed of CLCN2 and CLCN6 through Lasso-Cox regression analysis in the training cohort from the Cancer Genome Atlas (TCGA). The testing and entire cohorts from TCGA and the GSE21034 from the Gene Expression Omnibus (GEO) were used as internal and independent external validation datasets. This signature could divide PCa patients into the high and low risk groups with different prognoses, was apparently correlated with clinical features, and was an independent excellent prognostic indicator. Enrichment analysis indicated our signature was primarily concentrated in cellular process and metabolic process. The expression patterns of CLCN2 and CLCN6 were detected in our own cohort based immunohistochemistry staining, and we found CLCN2 and CLCN6 were highly expressed in PCa tissues compared with benign tissues and positively associated with higher Gleason score and shorter BCR-free time. Functional experiments revealed that CLCN2 and CLCN6 downregulation inhibited cell proliferation, colony formation, invasion, and migration, but prolonged cell cycle and promoted apoptosis. Furthermore, Seahorse assay showed that silencing CLCN2 or CLCN6 exerted potential inhibitory effects on energy metabolism in PCa. Collectively, our signature could provide a novel and robust strategy for the prognostic evaluation and improve treatment decision making for PCa patients.

Mitochondrial Function and Parkinson's Disease: From the Perspective of the Electron Transport Chain

Parkinson’s disease (PD) is known as a mitochondrial disease. Some even regarded it specifically as a disorder of the complex I of the electron transport chain (ETC). The ETC is fundamental for mitochondrial energy production which is essential for neuronal health. In the past two decades, more than 20 PD-associated genes have been identified. Some are directly involved in mitochondrial functions, such as PRKN, PINK1, and DJ-1. While other PD-associate genes, such as LRRK2, SNCA, and GBA1, regulate lysosomal functions, lipid metabolism, or protein aggregation, some have been shown to indirectly affect the electron transport chain. The recent identification of CHCHD2 and UQCRC1 that are critical for functions of complex IV and complex III, respectively, provide direct evidence that PD is more than just a complex I disorder. Like UQCRC1 in preventing cytochrome c from release, functions of ETC proteins beyond oxidative phosphorylation might also contribute to the pathogenesis of PD.

Metabolic Therapy of Heart Failure: Is There a Future for B Vitamins?

Heart failure (HF) is a plague of the aging population in industrialized countries that continues to cause many deaths despite intensive research into more effective treatments. Although the therapeutic arsenal to face heart failure has been expanding, the relatively short life expectancy of HF patients is pushing towards novel therapeutic strategies. Heart failure is associated with drastic metabolic disorders, including severe myocardial mitochondrial dysfunction and systemic nutrient deprivation secondary to severe cardiac dysfunction. To date, no effective therapy has been developed to restore the cardiac energy metabolism of the failing myocardium, mainly due to the metabolic complexity and intertwining of the involved processes. Recent years have witnessed a growing scientific interest in natural molecules that play a pivotal role in energy metabolism with promising therapeutic effects against heart failure. Among these molecules, B vitamins are a class of water soluble vitamins that are directly involved in energy metabolism and are of particular interest since they are intimately linked to energy metabolism and HF patients are often B vitamin deficient. This review aims at assessing the value of B vitamin supplementation in the treatment of heart failure.

Roles of LncRNAs in Regulating Mitochondrial Dysfunction in Septic Cardiomyopathy

Sepsis is an abnormal systemic inflammatory response of the host immune system to infection and can lead to fatal multiorgan dysfunction syndrome. Epidemiological studies have shown that approximately 10-70% of sepsis cases can lead to septic cardiomyopathy. Since the pathogenesis of septic cardiomyopathy is not clear, it is difficult for medical doctors to treat the disease. Therefore, finding effective interventions to prevent and reduce myocardial damage in septic cardiomyopathy is clinically significant. Epigenetics is the study of stable genetic phenotype inheritance that does not involve changing gene sequences. Epigenetic inheritance is affected by both gene and environmental regulation. Epigenetic studies focus on the modification and influence of chromatin structure, mainly including chromatin remodelling, DNA methylation, histone modification and noncoding RNA (ncRNA)-related mechanisms. Recently, long ncRNA (lncRNA)-related mechanisms have been the focus of epigenetic studies. LncRNAs are expected to become important targets to prevent, diagnose and treat human diseases. As the energy metabolism centre of cells, mitochondria are important targets in septic cardiomyopathy. Intervention measures to prevent and treat mitochondrial damage are of great significance for improving the prognosis of septic cardiomyopathy. LncRNAs play important roles in life activities. Recently, studies have focused on the involvement of lncRNAs in regulating mitochondrial dysfunction. However, few studies have revealed the involvement of lncRNAs in regulating mitochondrial dysfunction in septic cardiomyopathy. In this article, we briefly review recent research in this area.

Genetic landscape of human mitochondrial genome using whole genome sequencing

Increasing evidences suggest that mitochondrial dysfunction is implicated in diseases and aging, and whole-genome sequencing (WGS) is the most unbiased method in analyzing the mitochondrial genome (mtDNA). However, the genetic landscape of mtDNA in the Chinese population has not been fully examined. Here, we described the genetic landscape of mtDNA using WGS data from Chinese individuals (n = 3241). We identified 3892 mtDNA variants, of which 3349 (86%) were rare variants. Interestingly, we observed a trend toward extreme heterogeneity of mtDNA variants. Our study observed a distinct purifying selection on mtDNA, which inhibits the accumulation of harmful heteroplasmies at the individual level: (1) mitochondrial dN/dS ratios were much less than 1; (2) the dN/dS ratio of heteroplasmies was higher than homoplasmies; (3) heteroplasmies had more indels and predicted deleterious variants than homoplasmies. Furthermore, we found that haplogroup M (20.27%) and D (20.15%) had the highest frequencies in the Chinese population, followed by B (18.51%) and F (16.45%). The number of variants per individual differed across haplogroup groups, with a higher number of homoplasmies for the M lineage. Meanwhile, mtDNA copy number was negatively correlated with age but positively correlated with the female sex. Finally, we developed an mtDNA variation database of Chinese populations called MTCards (http://genemed.tech/mtcards/) to facilitate the query of mtDNA variants in this study. In summary, these findings contribute to different aspects of understanding mtDNA, providing a better understanding of the genetic basis of mitochondrial-related diseases.

Production, isolation and characterization of C-phycocyanin from a new halo-tolerant Cyanobacterium aponinum using seawater

A halo-tolerant Cyanobacterium aponinum PCC 10605 was applied for the first time to produce high-level C-phycocyanin (C-PC). Combined with chemical extraction with sodium phosphate buffer and physical treatment using high pressure homogenization, a higher titer of C-PC was achieved. The culture conditions were optimized by mixing nitrate and ammonia ions, 2% carbon dioxide, and conditional light intensity. Thus, strain PCC10605 produced the highest titer C-PC of 0.652 g/g-DCW in the N1A2 medium with 10% light intensity and 16:8 light-period on day 7. PCC10605 accumulated 0.51 g-CPC/g-DCW at 20 g/L NaCl, while it grew normally in seawater with 30 g/L salinity, thus confirmed that PCC10605 was halo-tolerant strain. Besides, PCC10605 survived in 0.12 g/L phosphate medium that has never been reported. Finally, the purified C-PC exhibited DPPH, superoxide scavenging activity and antibacterial activity, which displayed 87.6%, and 18.7% removal of free radical, and 1.98 cm of inhibition zone for Escherichia coli.

ATP Synthase and Mitochondrial Bioenergetics Dysfunction in Alzheimer's Disease

Alzheimer’s Disease (AD) is the most common neurodegenerative disorder in our society, as the population ages, its incidence is expected to increase in the coming decades. The etiopathology of this disease still remains largely unclear, probably because of the highly complex and multifactorial nature of AD. However, the presence of mitochondrial dysfunction has been broadly described in AD neurons and other cellular populations within the brain, in a wide variety of models and organisms, including post-mortem humans. Mitochondria are complex organelles that play a crucial role in a wide range of cellular processes, including bioenergetics. In fact, in mammals, including humans, the main source of cellular ATP is the oxidative phosphorylation (OXPHOS), a process that occurs in the mitochondrial electron transfer chain (ETC). The last enzyme of the ETC, and therefore the ulterior generator of ATP, is the ATP synthase. Interestingly, in mammalian cells, the ATP synthase can also degrade ATP under certain conditions (ATPase), which further illustrates the crucial role of this enzyme in the regulation of cellular bioenergetics and metabolism. In this collaborative review, we aim to summarize the knowledge of the presence of dysregulated ATP synthase, and of other components of mammalian mitochondrial bioenergetics, as an early event in AD. This dysregulation can act as a trigger of the dysfunction of the organelle, which is a clear component in the etiopathology of AD. Consequently, the pharmacological modulation of the ATP synthase could be a potential strategy to prevent mitochondrial dysfunction in AD.

Danhong injection enhances the therapeutic effect of mannitol on hemispheric ischemic stroke by ameliorating blood-brain barrier disruption

Mannitol, a representative of hyperosmolar therapy, is indispensable for the treatment of malignant cerebral infarction, but its therapeutic effect is limited by its exacerbation of blood-brain barrier (BBB) disruption. This study was to explore whether Danhong injection (DHI), a standardized product extracted from Salvia miltiorrhiza Bunge and Carthamus tinctorius L., inhibits the destructive effect of mannitol on BBB and thus enhancing the treatment of hemispheric ischemic stroke. SD rats were subjected to pMCAO followed by intravenous bolus injections of mannitol with/without DHI intervention. Neurological deficit score, brain edema, infarct volume at 24 h after MCAO and histopathology, microvascular ultrastructure, immunohistochemistry and immunofluorescence staining of endothelial cell junctions, energy metabolism in the ischemic penumbra were assessed. Intravenous mannitol after MCAO resulted in a decrease in 24 h mortality and cerebral edema, whereas no significant benefit on neurological deficits, infarct volume and microvascular ultrastructure. Moreover, mannitol led to the loss of endothelial integrity, manifested by the decreased expression of occludin, junctional adhesion molecule-1 (JAM-1) and zonula occluden-1 (ZO-1) and the discontinuity of occludin staining around the periphery of endothelial cells. Meanwhile, after mannitol treatment, energy-dependent vimentin and F-actin, ATP content, and ATP5D expression were down-regulated, while MMP2 and MMP9 expression increased in the ischemic penumbra. All the insults after mannitol treatment were attenuated by addition of intravenous DHI. The results suggest DHI as a potential remedy to attenuate mannitol-related BBB disruption, and the potential of DHI to upregulate energy metabolism and inhibit the activity of MMPs is likely attributable to its effects observed.

From OCR and ECAR to energy: Perspectives on the design and interpretation of bioenergetics studies

Biological energy transduction underlies all physiological phenomena in cells. The metabolic systems that support energy transduction have been of great interest due to their association with numerous pathologies including diabetes, cancer, rare genetic diseases, and aberrant cell death. Commercially available bioenergetics technologies (e.g., extracellular flux analysis, high-resolution respirometry, fluorescent dye kits, etc.) have made practical assessment of metabolic parameters widely accessible. This has facilitated an explosion in the number of studies exploring, in particular, the biological implications of oxygen consumption rate (OCR) and substrate level phosphorylation via glycolysis (i.e., via extracellular acidification rate (ECAR)). Though these technologies have demonstrated substantial utility and broad applicability to cell biology research, they are also susceptible to historical assumptions, experimental limitations, and other caveats that have led to premature and/or erroneous interpretations. This review enumerates various important considerations for designing and interpreting cellular and mitochondrial bioenergetics experiments, some common challenges and pitfalls in data interpretation, and some potential "next steps" to be taken that can address these highlighted challenges.

Disease Modeling of Mitochondrial Cardiomyopathy Using Patient-Specific Induced Pluripotent Stem Cells

Mitochondrial cardiomyopathy (MCM) is characterized as an oxidative phosphorylation disorder of the heart. More than 100 genetic variants in nuclear or mitochondrial DNA have been associated with MCM. However, the underlying molecular mechanisms linking genetic variants to MCM are not fully understood due to the lack of appropriate cellular and animal models. Patient-specific induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iPSC-CMs) provide an attractive experimental platform for modeling cardiovascular diseases and predicting drug efficacy to such diseases. Here we introduce the pathological and therapeutic studies of MCM using iPSC-CMs and discuss the questions and latest strategies for research using iPSC-CMs.

The interplay between mitochondria and store-operated Ca2+ entry: Emerging insights into cardiac diseases

Store‐operated Ca²⁺ entry (SOCE) machinery, including Orai channels, TRPCs, and STIM1, is key to cellular calcium homeostasis. The following characteristics of mitochondria are involved in the physiological and pathological regulation of cells: mitochondria mediate calcium uptake through calcium uniporters; mitochondria are regulated by mitochondrial dynamic related proteins (OPA1, MFN1/2, and DRP1) and form mitochondrial networks through continuous fission and fusion; mitochondria supply NADH to the electron transport chain through the Krebs cycle to produce ATP; under stress, mitochondria will produce excessive reactive oxygen species to regulate mitochondria‐endoplasmic reticulum interactions and the related signalling pathways. Both SOCE and mitochondria play critical roles in mediating cardiac hypertrophy, diabetic cardiomyopathy, and cardiac ischaemia‐reperfusion injury. All the mitochondrial characteristics mentioned above are determinants of SOCE activity, and vice versa. Ca²⁺ signalling dictates the reciprocal regulation between mitochondria and SOCE under the specific pathological conditions of cardiomyocytes. The coupling of mitochondria and SOCE is essential for various pathophysiological processes in the heart. Herein, we review the research focussing on the reciprocal regulation between mitochondria and SOCE and provide potential interplay patterns in cardiac diseases.

Out-of-Equilibrium Biophysical Chemistry: The Case for Multidimensional, Integrated Single-Molecule Approaches

Out-of-equilibrium processes are ubiquitous across living organisms and all structural hierarchies of life. At the molecular scale, out-of-equilibrium processes (for example, enzyme catalysis, gene regulation, and motor protein functions) cause biological macromolecules to sample an ensemble of conformations over a wide range of time scales. Quantifying and conceptualizing the structure–dynamics to function relationship is challenging because continuously evolving multidimensional energy landscapes are necessary to describe nonequilibrium biological processes in biological macromolecules. In this perspective, we explore the challenges associated with state-of-the-art experimental techniques to understanding biological macromolecular function. We argue that it is time to revisit how we probe and model functional out-of-equilibrium biomolecular dynamics. We suggest that developing integrated single-molecule multiparametric force–fluorescence instruments and using advanced molecular dynamics simulations to study out-of-equilibrium biomolecules will provide a path towards understanding the principles of and mechanisms behind the structure–dynamics to function paradigm in biological macromolecules.

Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders

Biomolecular condensates are membraneless organelles (MLOs) that form dynamic, chemically distinct subcellular compartments organizing macromolecules such as proteins, RNA, and DNA in unicellular prokaryotic bacteria and complex eukaryotic cells. Separated from surrounding environments, MLOs in the nucleoplasm, cytoplasm, and mitochondria assemble by liquid-liquid phase separation (LLPS) into transient, non-static, liquid-like droplets that regulate essential molecular functions. LLPS is primarily controlled by post-translational modifications (PTMs) that fine-tune the balance between attractive and repulsive charge states and/or binding motifs of proteins. Aberrant phase separation due to dysregulated membrane lipid rafts and/or PTMs, as well as the absence of adequate hydrotropic small molecules such as ATP, or the presence of specific RNA proteins can cause pathological protein aggregation in neurodegenerative disorders. Melatonin may exert a dominant influence over phase separation in biomolecular condensates by optimizing membrane and MLO interdependent reactions through stabilizing lipid raft domains, reducing line tension, and maintaining negative membrane curvature and fluidity. As a potent antioxidant, melatonin protects cardiolipin and other membrane lipids from peroxidation cascades, supporting protein trafficking, signaling, ion channel activities, and ATPase functionality during condensate coacervation or dissolution. Melatonin may even control condensate LLPS through PTM and balance mRNA- and RNA-binding protein composition by regulating N6-methyladenosine (m6A) modifications. There is currently a lack of pharmaceuticals targeting neurodegenerative disorders via the regulation of phase separation. The potential of melatonin in the modulation of biomolecular condensate in the attenuation of aberrant condensate aggregation in neurodegenerative disorders is discussed in this review.

How rotating ATP synthases can modulate membrane structure

F1Fo-ATP synthase (ATP synthase) is a central membrane protein that synthetizes most of the ATP in the cell through a rotational movement driven by a proton gradient across the hosting membrane. In mitochondria, ATP synthases can form dimers through specific interactions between some subunits of the protein. The dimeric form of ATP synthase provides the protein with a spontaneous curvature that sustain their arrangement at the rim of the high-curvature edges of mitochondrial membrane (cristae). Also, a direct interaction with cardiolipin, a lipid present in the inner mitochondrial membrane, induces the dimerization of ATP synthase molecules along cristae. The deletion of those biochemical interactions abolishes the protein dimerization producing an altered mitochondrial function and morphology. Mechanically, membrane bending is one of the key deformation modes by which mitochondrial membranes can be shaped. In particular, bending rigidity and spontaneous curvature are important physical factors for membrane remodelling. Here, we discuss a complementary mechanism whereby the rotatory movement of the ATP synthase might modify the mechanical properties of lipid bilayers and contribute to the formation and regulation of the membrane invaginations.

Mitonuclear Coevolution, but not Nuclear Compensation, Drives Evolution of OXPHOS Complexes in Bivalves

In Metazoa, four out of five complexes involved in oxidative phosphorylation (OXPHOS) are formed by subunits encoded by both the mitochondrial (mtDNA) and nuclear (nuDNA) genomes, leading to the expectation of mitonuclear coevolution. Previous studies have supported coadaptation of mitochondria-encoded (mtOXPHOS) and nuclear-encoded OXPHOS (nuOXPHOS) subunits, often specifically interpreted with regard to the “nuclear compensation hypothesis,” a specific form of mitonuclear coevolution where nuclear genes compensate for deleterious mitochondrial mutations due to less efficient mitochondrial selection. In this study, we analyzed patterns of sequence evolution of 79 OXPHOS subunits in 31 bivalve species, a taxon showing extraordinary mtDNA variability and including species with “doubly uniparental” mtDNA inheritance. Our data showed strong and clear signals of mitonuclear coevolution. NuOXPHOS subunits had concordant topologies with mtOXPHOS subunits, contrary to previous phylogenies based on nuclear genes lacking mt interactions. Evolutionary rates between mt and nuOXPHOS subunits were also highly correlated compared with non-OXPHO-interacting nuclear genes. Nuclear subunits of chimeric OXPHOS complexes (I, III, IV, and V) also had higher dN/dS ratios than Complex II, which is formed exclusively by nuDNA-encoded subunits. However, we did not find evidence of nuclear compensation: mitochondria-encoded subunits showed similar dN/dS ratios compared with nuclear-encoded subunits, contrary to most previously studied bilaterian animals. Moreover, no site-specific signals of compensatory positive selection were detected in nuOXPHOS genes. Our analyses extend the evidence for mitonuclear coevolution to a new taxonomic group, but we propose a reconsideration of the nuclear compensation hypothesis.

Tackling Dysfunction of Mitochondrial Bioenergetics in the Brain

Oxidative phosphorylation (OxPhos) is the basic function of mitochondria, although the landscape of mitochondrial functions is continuously growing to include more aspects of cellular homeostasis. Thanks to the application of -omics technologies to the study of the OxPhos system, novel features emerge from the cataloging of novel proteins as mitochondrial thus adding details to the mitochondrial proteome and defining novel metabolic cellular interrelations, especially in the human brain. We focussed on the diversity of bioenergetics demand and different aspects of mitochondrial structure, functions, and dysfunction in the brain. Definition such as 'mitoexome', 'mitoproteome' and 'mitointeractome' have entered the field of 'mitochondrial medicine'. In this context, we reviewed several genetic defects that hamper the last step of aerobic metabolism, mostly involving the nervous tissue as one of the most prominent energy-dependent tissues and, as consequence, as a primary target of mitochondrial dysfunction. The dual genetic origin of the OxPhos complexes is one of the reasons for the complexity of the genotype-phenotype correlation when facing human diseases associated with mitochondrial defects. Such complexity clinically manifests with extremely heterogeneous symptoms, ranging from organ-specific to multisystemic dysfunction with different clinical courses. Finally, we briefly discuss the future directions of the multi-omics study of human brain disorders.

Oxidative Stress, Mitochondrial Dysfunction, and Neuroprotection of Polyphenols with Respect to Resveratrol in Parkinson's Disease

Parkinson’s disease (PD) is the second most common neurodegenerative disease and is characterized by dopaminergic neuronal loss. The exact pathogenesis of PD is complex and not yet completely understood, but research has established the critical role mitochondrial dysfunction plays in the development of PD. As the main producer of cytosolic reactive oxygen species (ROS), mitochondria are particularly susceptible to oxidative stress once an imbalance between ROS generation and the organelle’s antioxidative system occurs. An overabundance of ROS in the mitochondria can lead to mitochondrial dysfunction and further vicious cycles. Once enough damage accumulates, the cell may undergo mitochondria-dependent apoptosis or necrosis, resulting in the neuronal loss of PD. Polyphenols are a group of natural compounds that have been shown to offer protection against various diseases, including PD. Among these, the plant-derived polyphenol, resveratrol, exhibits neuroprotective effects through its antioxidative capabilities and provides mitochondria protection. Resveratrol also modulates crucial genes involved in antioxidative enzymes regulation, mitochondrial dynamics, and cellular survival. Additionally, resveratrol offers neuroprotective effects by upregulating mitophagy through multiple pathways, including SIRT-1 and AMPK/ERK pathways. This compound may provide potential neuroprotective effects, and more clinical research is needed to establish the efficacy of resveratrol in clinical settings.

Fluorescent Materials for Monitoring Mitochondrial Biology

Mitochondria play important roles in diverse cellular processes such as energy production, cellular metabolism, and apoptosis to promote cell death. To investigate mitochondria-associated biological processes such as structure, dynamics, morphological change, metabolism, and mitophagy, there exists a continuous demand for visualizing and monitoring techniques elucidating mitochondrial biology and disease-relevancy. Due to the advantages of high sensitivity and practicality, fluorescence phenomena have been most widely used as scientific techniques for the visualization of biological phenomena and systems. In this review, we briefly overview the different types of fluorescent materials such as chemical probes, peptide- or protein-based probes, and nanomaterials for monitoring mitochondrial biology.

Overexpression of Peroxisome Proliferator-Activated Receptor γ Coactivator 1-α Protects Cardiomyocytes from Lipopolysaccharide-Induced Mitochondrial Damage and Apoptosis

Mitochondrial damage is considered one of the main pathogenetic mechanisms in septic cardiomyopathy. Peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) is critical for maintaining energy homeostasis in different organs and in various physiological and pathological states. It is also a key regulator gene in mitochondrial metabolism. In this study, we investigated whether regulation of the PGC-1α gene had protective effects on septic cardiomyopathy. We developed a rat model of septic cardiomyopathy. H9c2 myocardiocytes were treated with lipopolysaccharide (LPS) and PGC-1α expression measured. PGC-1α-overexpressing lentivirus was used to transfect H9c2 cells. ZLN005 was used to activate PGC-1α. The effect of the inhibition of PGC-1α expression on myocardial cell injury and its underlying mechanisms were also explored. Cell viability was measured by CCK-8 assay. Mitochondrial damage was determined by measuring cellular ATP, reactive oxygen species, and the mitochondrial membrane potential. An apoptosis analysis kit was used to measure cellular apoptosis. Mitochondrial DNA was extracted and real-time PCR performed. LC3B, mitochondrial transcription factor A (TFA), P62, Bcl2, and Bax were determined by immunofluorescence. LC3B, TFA, P62, Parkin, PTEN-induced putative kinase 1, and PGC-1α proteins were determined by Western blotting. We found mitochondrial damage and apoptotic cells in the myocardial tissue of rats with septic cardiomyopathy and in LPS-treated cardiomyocytes. PGC-1α expression was decreased in the late phase of septic cardiomyopathy and in LPS-treated cardiomyocytes. PGC-1α activation by ZLN005 and PGC-1α overexpression reduced apoptosis in myocardiocytes after LPS incubation. PGC-1α gene overexpression alleviated LPS-induced cardiomyocyte mitochondrial damage by activating mitochondrial biogenesis and autophagy functions. Our study indicated that mitochondrial damage and apoptosis occurred in septic cardiomyopathy and LPS-treated cardiomyocytes. The low expression level of PGC-1α protein may have contributed to this damage. By activating the expression of PGC-1α, apoptosis was reduced in cardiomyocytes. The underlying mechanism may be that PGC-1α can activate mitochondrial biogenesis and autophagy functions, reducing mitochondrial damage and thereby reducing apoptosis.

Transcriptional Changes after Enniatins A, A1, B and B1 Ingestion in Rat Stomach, Liver, Kidney and Lower Intestine

Enniatins (ENs) are depsipeptide mycotoxins produced by Fusarium fungi. They are known for their capacity to modulate cell membrane permeability and disruption of ionic gradients, affecting cell homeostasis and initiating oxidative stress mechanisms. The effect of the acute toxicity of ENs A, A1, B and B1 at two different concentrations after 8 h of exposure was analysed in Wistar rats by a transcriptional approach. The following key mitochondrial and nuclear codified genes related to the electron transport chain were considered for gene expression analysis in stomach, liver, kidney and lower intestine by quantitative Real-Time PCR: mitochondrially encoded NADH dehydrogenase 1 (MT-ND1), mitochondrially encoded cytochrome c oxidase 1 (MT-COX1), succinate dehydrogenase flavoprotein subunit A and ATP synthase F1 subunit alpha, respectively. Moreover, the expression of markers involved in oxidative stresssuperoxide dismutase 1 (SOD1), glutathione peroxidase 1 (Gpx1), heme oxygenase 1, apoptosis B-cell lymphoma 2, Bcl2 Associated protein X (Bax), tumor suppressor protein (p53), inhibition of apoptosis nuclear factor kappa of activated B cells, immune system interleukin 1β and intestinal tight junction Occludin merely in lower intestine tissues have been investigated. For mitochondrial genes, the main differences were observed for MT-ND1 and MT-COX1, showing its deficiency in all selected organs. With regard to the intestinal barrier’s cellular response to oxidative stress, the activity of the antioxidant gene SOD1 was decreased in a dose-dependent manner. Similarly, the catalytic enzyme GPx1 was also downregulated though merely at medium dose employed. On the contrary, the pro-apoptotic Bax and p53 regulators were activated after ENs exposure, reporting a significant increase in their expression. Furthermore, the alteration of intestinal permeability was assessed by the abnormal activity of the tight junction protein occludin. In summary, ENs may generate mitochondrial disorders and induce oxidative stress in intestinal barrier function.

Perfluorooctane sulfonate continual exposure impairs glucose-stimulated insulin secretion via SIRT1-induced upregulation of UCP2 expression

Per- and polyfluoroalkyl substances (PFASs) are environmentally and biologically persistent anthropogenic chemicals linked to adverse health outcomes. Epidemiological data have revealed association between exposure to specific PFAS and disruption of insulin level in bodies. However, the effect of PFASs on insulin secretion and the responsible molecular mechanism are poorly understood. In the present study, we used perfluorooctane sulfonate (PFOS) as a representative PFAS family member to investigate its effect on the insulin secretion in mouse pancreatic β cells (β-TC-6). Our results showed that exposure to PFOS inhibited silent information regulator 1 (SIRT1) activity, and molecular simulation showed PFOS could fit into the pocket overlapped with the nicotinamide adenine dinucleotide (NAD⁺) binding cavity in SIRT1. PFOS exposure upregulated uncoupling protein 2 (UCP2) expression, and this upregulation was blunted in the presence of Ex-527, a SIRT1 specific inhibitor. The mitochondria membrane potential (ΔΨm), as well as the glucose-induced ATP production and Ca²⁺ influx decreased under PFOS treatment. PFOS continual exposure (48 h) impaired glucose stimulated insulin secretion (GSIS), while the gene expression of insulin was not significantly altered. Importantly, the SIRT1 activator and UCP2 inhibitor could partly reverse the PFOS-induced impairment of GSIS. Taken together, the results suggested that PFOS continual exposure could inhibit SIRT1 activity, and the SIRT1-UCP2 pathway mediated, at least partially, the PFOS induced GSIS impairment.

Interplay between Mitochondrial Protein Import and Respiratory Complexes Assembly in Neuronal Health and Degeneration

The fact that >99% of mitochondrial proteins are encoded by the nuclear genome and synthesised in the cytosol renders the process of mitochondrial protein import fundamental for normal organelle physiology. In addition to this, the nuclear genome comprises most of the proteins required for respiratory complex assembly and function. This means that without fully functional protein import, mitochondrial respiration will be defective, and the major cellular ATP source depleted. When mitochondrial protein import is impaired, a number of stress response pathways are activated in order to overcome the dysfunction and restore mitochondrial and cellular proteostasis. However, prolonged impaired mitochondrial protein import and subsequent defective respiratory chain function contributes to a number of diseases including primary mitochondrial diseases and neurodegeneration. This review focuses on how the processes of mitochondrial protein translocation and respiratory complex assembly and function are interlinked, how they are regulated, and their importance in health and disease.

Deletion of the ATP2 Gene in Candida albicans Blocks Its Escape From Macrophage Clearance

Macrophages provide the first-line defense against invasive fungal infections and, therefore, escape from macrophage becomes the basis for the establishment of Candida albicans invasive infection. Here, we found that deletion of ATP2 (atp2Δ/Δ) in C. albicans resulted in a dramatic decrease from 69.2% (WT) to 1.2% in the escape rate in vitro. The effect of ATP2 on macrophage clearance stands out among the genes currently known to affect clearance. In the normal mice, the atp2Δ/Δ cells were undetectable in major organs 72 h after systemic infection, while WT cells persisted in vivo. However, in the macrophage-depleted mice, atp2Δ/Δ could persist for 72 h at an amount comparable to that at 24 h. Regarding the mechanism, WT cells sustained growth and switched to hyphal form, which was more conducive to escape from macrophages, in media that mimic the glucose-deficient environment in macrophages. In contrast, atp2Δ/Δ cells can remained viable but were unable to complete morphogenesis in these media, resulting in them being trapped within macrophages in the yeast form. Meanwhile, atp2Δ/Δ cells were killed by oxidative stress in alternative carbon sources by 2- to 3-fold more than WT cells. Taken together, ATP2 deletion prevents C. albicans from escaping macrophage clearance, and therefore ATP2 has a functional basis as a drug target that interferes with macrophage clearance.

A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation

Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.

The ATP Synthase Deficiency in Human Diseases

Human diseases range from gene-associated to gene-non-associated disorders, including age-related diseases, neurodegenerative, neuromuscular, cardiovascular, diabetic diseases, neurocognitive disorders and cancer. Mitochondria participate to the cascades of pathogenic events leading to the onset and progression of these diseases independently of their association to mutations of genes encoding mitochondrial protein. Under physiological conditions, the mitochondrial ATP synthase provides the most energy of the cell via the oxidative phosphorylation. Alterations of oxidative phosphorylation mainly affect the tissues characterized by a high-energy metabolism, such as nervous, cardiac and skeletal muscle tissues. In this review, we focus on human diseases caused by altered expressions of ATP synthase genes of both mitochondrial and nuclear origin. Moreover, we describe the contribution of ATP synthase to the pathophysiological mechanisms of other human diseases such as cardiovascular, neurodegenerative diseases or neurocognitive disorders.

Continuous assessment of metabolic activity of mitochondria using resonance Raman microspectroscopy

Dysfunctional mitochondrial activity can lead to a variety of different diseases. As such, there exists a need to quantify changes in mitochondria function as it relates to these specific diseased states. Here, we present the use of resonance Raman (RR) spectroscopy as a tool to determine changes in isolated mitochondrial activity. RR spectroscopy, using 532 nm as the excitation source, specifically provides information on the reduction and oxidation (RedOx) state of cytochrome c, which is determined by the activity of protein complexes in the electron transport chain (ETC). In this model, injection of the substrate succinate into the mitochondrial sample is used to drive the ETC, which causes a subsequent change in cytochrome c RedOx state. This change in RedOx state is tracked by RR spectroscopy. This tool gives real-time information on the rise and fall of the amount of reduced cytochrome c within the mitochondrial sample, providing a method for rapid assessment of mitochondrial metabolism that has broad applications in both basic science and medical research.

Manickam D. Targeting the blood-brain barrier for the delivery of stroke therapies

A variety of neuroprotectants have shown promise in treating ischemic stroke, yet their delivery to the brain remains a challenge. The endothelial cells lining the blood-brain barrier (BBB) are emerging as a dynamic factor in the response to neurological injury and disease, and the endothelial-neuronal matrix coupling is fundamentally neuroprotective. In this review, we discuss approaches that target the endothelium for drug delivery both across the BBB and to the BBB as a viable strategy to facilitate neuroprotective effects, using the example of brain-derived neurotrophic factor (BDNF). We highlight the advances in cell-derived extracellular vesicles (EVs) used for CNS targeting and drug delivery. We also discuss the potential of engineered EVs as a potent strategy to deliver BDNF or other drug candidates to the ischemic brain, particularly when coupled with internal components like mitochondria that may increase cellular energetics in injured endothelial cells.

Mitochondrial genome stability in human: understanding the role of DNA repair pathways

Mitochondria are semiautonomous organelles in eukaryotic cells and possess their own genome that replicates independently. Mitochondria play a major role in oxidative phosphorylation due to which its genome is frequently exposed to oxidative stress. Factors including ionizing radiation, radiomimetic drugs and replication fork stalling can also result in different types of mutations in mitochondrial DNA (mtDNA) leading to genome fragility. Mitochondria from myopathies, dystonia, cancer patient samples show frequent mtDNA mutations such as point mutations, insertions and large-scale deletions that could account for mitochondria-associated disease pathogenesis. The mechanism by which such mutations arise following exposure to various DNA-damaging agents is not well understood. One of the well-studied repair pathways in mitochondria is base excision repair. Other repair pathways such as mismatch repair, homologous recombination and microhomology-mediated end joining have also been reported. Interestingly, nucleotide excision repair and classical nonhomologous DNA end joining are not detected in mitochondria. In this review, we summarize the potential causes of mitochondrial genome fragility, their implications as well as various DNA repair pathways that operate in mitochondria.

Mitochondria-Anchored Molecular Thermometer Quantitatively Monitoring Cellular Inflammations

Temperature in mitochondria can be a critical indicator of cell metabolism. Given the highly dynamic and inhomogeneous nature of mitochondria, it remains a big challenge to quantitatively monitor the local temperature changes during different cellular processes. To implement this task, we extend our strategy on mitochondria-anchored thermometers from "on-off" probe Mito-TEM to a ratiometric probe Mito-TEM 2.0 based on the Förster resonance energy transfer mechanism. Mito-TEM 2.0 exhibits not only a sensitive response to temperature through the ratiometric changes of dual emissions but also the specific immobilization in mitochondria via covalent bonds. Both characters support accurate and reliable detection of local temperature for a long time, even in malfunctioning mitochondria. By applying Mito-TEM 2.0 in fluorescence ratiometric imaging of cells and zebrafishes, we make a breakthrough in the quantitative visualization of mitochondrial temperature rises in different inflammation states.

Molecular and Supramolecular Structure of the Mitochondrial Oxidative Phosphorylation System: Implications for Pathology

Under aerobic conditions, mitochondrial oxidative phosphorylation (OXPHOS) converts the energy released by nutrient oxidation into ATP, the currency of living organisms. The whole biochemical machinery is hosted by the inner mitochondrial membrane (mtIM) where the protonmotive force built by respiratory complexes, dynamically assembled as super-complexes, allows the F1FO-ATP synthase to make ATP from ADP + Pi. Recently mitochondria emerged not only as cell powerhouses, but also as signaling hubs by way of reactive oxygen species (ROS) production. However, when ROS removal systems and/or OXPHOS constituents are defective, the physiological ROS generation can cause ROS imbalance and oxidative stress, which in turn damages cell components. Moreover, the morphology of mitochondria rules cell fate and the formation of the mitochondrial permeability transition pore in the mtIM, which, most likely with the F1FO-ATP synthase contribution, permeabilizes mitochondria and leads to cell death. As the multiple mitochondrial functions are mutually interconnected, changes in protein composition by mutations or in supercomplex assembly and/or in membrane structures often generate a dysfunctional cascade and lead to life-incompatible diseases or severe syndromes. The known structural/functional changes in mitochondrial proteins and structures, which impact mitochondrial bioenergetics because of an impaired or defective energy transduction system, here reviewed, constitute the main biochemical damage in a variety of genetic and age-related diseases.

Mitochondrial Permeability Transition: A Pore Intertwines Brain Aging and Alzheimer's Disease

Advanced age is the greatest risk factor for aging-related brain disorders including Alzheimer's disease (AD). However, the detailed mechanisms that mechanistically link aging and AD remain elusive. In recent years, a mitochondrial hypothesis of brain aging and AD has been accentuated. Mitochondrial permeability transition pore (mPTP) is a mitochondrial response to intramitochondrial and intracellular stresses. mPTP overactivation has been implicated in mitochondrial dysfunction in aging and AD brains. This review summarizes the up-to-date progress in the study of mPTP in aging and AD and attempts to establish a link between brain aging and AD from a perspective of mPTP-mediated mitochondrial dysfunction.

Extracellular Mitochondria Signals in CNS Disorders

Mitochondria actively participate in the regulation of cell respiratory mechanisms, metabolic processes, and energy homeostasis in the central nervous system (CNS). Because of the requirement of high energy, neuronal functionality and viability are largely dependent on mitochondrial functionality. In the context of CNS disorders, disruptions of metabolic homeostasis caused by mitochondrial dysfunction lead to neuronal cell death and neuroinflammation. Therefore, restoring mitochondrial function becomes a primary therapeutic target. Recently, accumulating evidence suggests that active mitochondria are secreted into the extracellular fluid and potentially act as non-cell-autonomous signals in CNS pathophysiology. In this mini-review, we overview findings that implicate the presence of cell-free extracellular mitochondria and the critical role of intercellular mitochondrial transfer in various rodent models of CNS disorders. We also discuss isolated mitochondrial allograft as a novel therapeutic intervention for CNS disorders.

Association between yoga, physiologic and psychologic health: A cross sectional study

PURPOSE

To compare markers of health associated with chronic diseases between yoga and non-yoga participants.

METHODS

30 participants were categorized as either: 1) "Yoga" engaging in yoga ≥2 times/week for ≥6 months, or 2) "Non-yoga" not engaging in yoga.

RESULTS

Perceived Stress Scale (PSS) and Beck Depression Inventory-II (BDI-II) scores were significantly different between the yoga and non-yoga groups (PSS: 8.0 vs. 17.5, respectively, p < 0.05; BDI-II: 1.0 vs. 5.5, respectively, p < 0.05). No significant differences were evident between groups for inflammatory markers nor Complex V of the mitochondrial electron transport chain. The erythrocyte sedimentation rate values differed between groups based on clinical cutoffs, with yoga participants categorized as normal (11.0 mm) and non-yoga above normal (21.5 mm).

CONCLUSION

This research supports that yoga participation is associated with lower PSS and BDI-II scores but does not support a relationship with markers of inflammation. Further research is warranted.

Blackout in the powerhouse: clinical phenotypes associated with defects in the assembly of OXPHOS complexes and the mitoribosome

Mitochondria produce the bulk of the energy used by almost all eukaryotic cells through oxidative phosphorylation (OXPHOS) which occurs on the four complexes of the respiratory chain and the F₁–F₀ ATPase. Mitochondrial diseases are a heterogenous group of conditions affecting OXPHOS, either directly through mutation of genes encoding subunits of OXPHOS complexes, or indirectly through mutations in genes encoding proteins supporting this process. These include proteins that promote assembly of the OXPHOS complexes, the post-translational modification of subunits, insertion of cofactors or indeed subunit synthesis. The latter is important for all 13 of the proteins encoded by human mitochondrial DNA, which are synthesised on mitochondrial ribosomes. Together the five OXPHOS complexes and the mitochondrial ribosome are comprised of more than 160 subunits and many more proteins support their biogenesis. Mutations in both nuclear and mitochondrial genes encoding these proteins have been reported to cause mitochondrial disease, many leading to defective complex assembly with the severity of the assembly defect reflecting the severity of the disease. This review aims to act as an interface between the clinical and basic research underpinning our knowledge of OXPHOS complex and ribosome assembly, and the dysfunction of this process in mitochondrial disease.

Conserved role of ATP synthase in mammalian cilia

We previously found that ATP synthases localize to male-specific sensory cilia and control the ciliary response by regulating polycystin signalling in Caenorhabditis elegans. Herein, we discovered that the ciliary localization of ATP synthase is evolutionarily conserved in mammals. We showed that the ATP synthase subunit F1β is colocalized with the cilia marker acetylated α-tubulin in both mammalian renal epithelial cells (MDCK) and normal mouse cholangiocytes (NMCs). Treatment with ATP synthase inhibitor oligomycin impaired ciliogenesis in MDCK cells, and F1β was co-immunoprecipitated with PKD2 in mammalian cells. Our study provides evidence for the evolutionarily conserved localization of ATP synthase in cilia from worm to mammals. Defects in ATP synthase can lead to ciliary dysfunction, which may be a potential mechanism of polycystic kidney disease.