A century of mitochondrial research: achievements and perspectives

Ovariectomy and High Fat-Sugar-Salt Diet Induced Alzheimer's Disease/Vascular Dementia Features in Mice

While the vast majority of Alzheimer's disease (AD) is non-familial, the animal models of AD that are commonly used for studying disease pathogenesis and development of therapy are mostly of a familial form. We aimed to generate a model reminiscent of the etiologies related to the common late-onset Alzheimer's disease (LOAD) sporadic disease that will recapitulate AD/dementia features. Naïve female mice underwent ovariectomy (OVX) to accelerate aging/menopause and were fed a high fat-sugar-salt diet to expose them to factors associated with increased risk of development of dementia/AD. The OVX mice fed a high fat-sugar-salt diet responded by dysregulation of glucose/insulin, lipid, and liver function homeostasis and increased body weight with slightly increased blood pressure. These mice developed AD-brain pathology (amyloid and tangle pathologies), gliosis (increased burden of astrocytes and activated microglia), impaied blood vessel density and neoangiogenesis, with cognitive impairment. Thus, OVX mice fed on a high fat-sugar-salt diet imitate a non-familial sporadic/environmental form of AD/dementia with vascular damage. This model is reminiscent of the etiologies related to the LOAD sporadic disease that represents a high portion of AD patients, with an added value of presenting concomitantly AD and vascular pathology, which is a common condition in dementia. Our model can, thereby, provide a valuable tool for studying disease pathogenesis and for the development of therapeutic approaches.

Iminoamido chelated iridium(III) and ruthenium(II) anticancer complexes with mitochondria-targeting ability and potential to overcome cisplatin resistance

A diverse set of neutral half-sandwich iminoamido iridium and ruthenium organometallic complexes is synthesized through the utilization of Schiff base pro-ligands with N˄N donors. Notably, these metal complexes with varying leaving groups (Cl- or OAc-) are formed by employing different quantities of the deprotonating agent NaOAc, and exhibit promising cytotoxicity against various cancer cell lines such as A549 and cisplatin-resistant A549/DDP lung cancer cells, as well as HeLa cells, with IC50 values spanning from 9.26 to 15.98 μM. Cytotoxicity and anticancer selectivity (SI: 1.9-2.4) of these metal complexes remain unaffected by variations in the metal center, leaving group, and ligand substitution. Further investigations reveal that these metal complexes specifically target mitochondria, leading to the depolarization of the mitochondrial membrane and instigating the production of intracellular reactive oxygen species. Furthermore, the metal complexes are found to induce late apoptosis and disrupt the cell cycle, leading to G2/M cell cycle arrest specifically in A549 cancer cells. In light of these findings, it is evident that the primary mechanism contributing to the anticancer effectiveness of these metal complexes is the redox pathway.

Integrated transcriptome and metabolome analysis reveals the molecular responses of Pardosa pseudoannulata to hypoxic environments

Terrestrial organisms are likely to face hypoxic stress during natural disasters such as floods or landslides, which can lead to inevitable hypoxic conditions for those commonly residing within soil. Pardosa pseudoannulata often inhabits soil crevices and has been extensively studied, yet research on its response to hypoxic stress remains unclear. Therefore, we investigated the adaptive strategies of Pardosa pseudoannulata under hypoxic stress using metabolomics and transcriptomics approaches. The results indicated that under hypoxic stress, metabolites related to energy and antioxidants such as ATP, D-glucose 6-phosphate, flavin adenine dinucleotide (FAD), and reduced L-glutathione were significantly differentially expressed. Pathways such as the citric acid (TCA) cycle and oxidative phosphorylation were significantly enriched. Transcriptome analysis and related assessments also revealed a significant enrichment of pathways associated with energy metabolism, suggesting that Pardosa pseudoannulata primarily copes with hypoxic environments by modulating energy metabolism and antioxidant-related substances.

Mitochondria-targeted neutral and cationic iridium(III) anticancer complexes chelating simple hybrid sp2-N/sp3-N donor ligands

Most platinum group-based cyclometalated neutral and cationic anticancer complexes with the general formula [(C^N)2Ir(XY)]0/+ (neutral complex: XY = bidentate anionic ligand; cationic complex: XY = bidentate neutral ligand) are notable owing to their intrinsic luminescence properties, good cell permeability, interaction with some biomolecular targets and unique mechanisms of action (MoAs). We herein synthesized a series of neutral and cationic amine-imine cyclometalated iridium(III) complexes using Schiff base ligands with sp2-N/sp3-N N^NH2 chelating donors. The cyclometalated iridium(III) complexes were identified by various techniques. They were stable in aqueous media, displayed moderate fluorescence and exhibited affinity toward bovine serum albumin (BSA). The complexes demonstrated promising cytotoxicity against lung cancer A549 cells, cisplatin-resistant lung cancer A549/DDP cells, cervical carcinoma HeLa cells and human liver carcinoma HepG2 cells, with IC50 values ranging from 9.98 to 19.63 μM. Unfortunately, these complexes had a low selectivity (selectivity index: 1.62-1.98) towards A549 cells and BEAS-2B normal cells. The charge pattern of the metal center (neutral or cationic) and ligand substituents showed little influence on the cytotoxicity and selectivity of these complexes. The study revealed that these complexes could target mitochondria, cause depolarization of the mitochondrial membrane, and trigger the production of intracellular ROS. Additionally, the complexes were observed to induce late apoptosis and perturb the cell cycle in the G2/M or S phase in A549 cells. Based on these results, it appears that the anticancer efficacy of these complexes was predominantly attributed to the redox mechanism.

Potent Half-Sandwich 16-/18-Electron Iridium(III) and Ruthenium(II) Anticancer Complexes with Readily Available Amine-Imine Ligands

The synthesis and biological evaluation of stable 16-electron half-sandwich complexes have remained scarce. We herein present the different coordination modes (16-electron or 18-electron) between half-sandwich iridium(III) complexes and ruthenium(II) complexes derived from the same amine-imine ligands chelating hybrid sp3-N/sp2-N donors. The 16-electron iridium(III) and 18-electron ruthenium(II) complexes with different counteranions were obtained and identified by various techniques. The promising cytotoxicity of these complexes against A549 lung cancer cells, cisplatin-resistant A549/DPP cells, cervical carcinoma HeLa cells, and human hepatocellular liver carcinoma HepG2 cells was observed with IC50 values ranging from 5.4 to 16.3 μM. Moreover, these complexes showed a certain selectivity (selectivity index: 2.1-3.7) toward A549 cells and BEAS-2B normal cells. The variation of metal center, counteranion, 16/18-electron coordination mode, and ligand substituents showed little influence on the cytotoxicity and selectivity of these complexes. The mechanism of action study showed that these complexes could target mitochondria, induce the depolarization of the mitochondrial membrane, and promote the generation of intracellular reactive oxygen species (ROS). Further, the induction of cell apoptosis and the perturbation of the cell cycle in the G0/G1 phase were also observed for these complexes. Overall, it seems that the redox mechanism dominated the anticancer efficacy of these complexes.

Reduced Peripheral Blood Mitochondrial DNA Copy Number as Identification Biomarker of Suspected Arsenic-Induced Liver Damage

Arsenic (As) can cause liver damage and liver cancer and is capable of seriously affecting human health. Therefore, it is important to identify biomarkers of arsenic-induced liver damage. Mitochondria are key targets of hepatotoxicity caused by arsenic. The mitochondrial DNA copy number (mtDNAcn) is the number of mitochondrial DNA (mtDNA) copies in the genome. mtDNA is vulnerable to exogenous chemical attacks, thus causing mtDNAcn to change after exposure to environmental pollutants. Therefore, mtDNAcn can serve as a potential marker to identify and assess the risk of diseases caused by exposure to environmental pollutants. In this study, we selected 272 arsenicosis patients (155 cases without liver damage and 117 cases with liver damage) and 218 participants not exposed to arsenic (155 cases without liver damage and 63 cases with liver damage) as subjects to investigate the correlation between peripheral blood mtDNAcn and arsenic-induced liver damage, as well as the ability of peripheral blood mtDNAcn to identify and assess the risk of arsenic-induced liver damage. Peripheral blood mtDNAcn in patients with arsenic-induced liver damage is significantly decreased and negatively correlated with serum ALT, AST, and GGT levels. The decrease of peripheral blood mtDNAcn was associated with an increased risk of arsenic-induced liver damage. The receiver operating characteristic (ROC) curve analysis indicated that peripheral blood mtDNAcn could specifically identify patients with liver damage in the arsenicosis group. The decision tree C5.0 model was established to identify arsenicosis in all patients with liver damage. Peripheral blood mtDNAcn was included in the model and played the most important role in the identification of arsenic-induced liver damage. This study provided a basis for the identification and evaluation of arsenic-induced liver damage by peripheral blood mtDNAcn, indicating that peripheral blood mtDNAcn is expected to be a potential biomarker of arsenic-induced liver damage, and provides clues for exploring the mechanism of arsenic-induced liver damage from mitochondria damage.

Half-Sandwich Iridium(III), Rhodium(III), and Ruthenium(II) Complexes Chelating Hybrid sp2-N/sp3-N Donor Ligands to Achieve Improved Anticancer Selectivity

The biological efficacy of half-sandwich platinum group organometallic complexes of the formula [(η5-Cpx)/(η6-arene)M(XY)Cl]0/+ (XY = bidentate ligands; Cpx = functionalized cyclopentadienyl; M = Ir, Rh, Ru, Os) has received considerable attention due to the significance of the metal center, chelating ligand, and Cpx/arene moieties in defining their anticancer potency and selectivity. With a facile access to the BIAN-derived imine-amine ligands using alkylaluminum as the reductant, we herein described the preparation and characterization of 16 half-sandwich Ir(III), Rh(III), and Ru(II) complexes chelating the hybrid sp2-N/sp3-N donor ligand. A nonplanar five-member metallacycle was confirmed by X-ray single-crystal structures of Ir1-Ir3, Ir7, Rh1, Ru1, and Ru4. The attempt to prepare imine-amido complexes using a base as the deprotonating agent led to the mixture of imine-amine complexes, within which the leaving group Cl- was displaced, and 16-electron imine-amido complexes without Cl-. The half-sandwich imine-amine complexes in this system underwent rapid hydrolysis in aqueous solution, exhibited weak photoluminescence, and showed the ability of binding to CT-DNA and BSA. The cytotoxicity of all imine-amine complexes against A549 lung cancer cell lines, HeLa cervical cancer cell lines, and 4T1 mouse breast cancer cells was determined by an MTT assay. The IC50 values of these complexes were in a range of 5.71-67.28 μM. Notably, most of these complexes displayed improved selectivity toward A549 cancer cells versus noncancerous BEAS-2B cells in comparison with the corresponding α-diimine complexes chelating the sp2-N/sp2-N donor ligand, which have been shown no selectivity in our previous report. The anticancer selectivity of these complexes appeared to be related to the redox-based mechanism including the catalytic oxidation of NADH to NAD+, reactive oxygen species (ROS) generation, and depolarization of the mitochondrial membrane. Further, inducing apoptosis of these complexes in A549 cancer cells and BEAS-2B normal cells also correlated with their anticancer selectivity, indicating the apoptosis mode of cell death in this system. In addition, these complexes could enter A549 cells via energy-dependent pathway and were able to impede the in vitro migration of A549 cells.

Mitochondria Have Made a Long Evolutionary Path from Ancient Bacteria Immigrants within Eukaryotic Cells to Essential Cellular Hosts and Key Players in Human Health and Disease

Mitochondria have made a long evolutionary path from ancient bacteria immigrants within the eukaryotic cell to become key players for the cell, assuming crucial multitasking skills critical for human health and disease. Traditionally identified as the powerhouses of eukaryotic cells due to their central role in energy metabolism, these chemiosmotic machines that synthesize ATP are known as the only maternally inherited organelles with their own genome, where mutations can cause diseases, opening up the field of mitochondrial medicine. More recently, the omics era has highlighted mitochondria as biosynthetic and signaling organelles influencing the behaviors of cells and organisms, making mitochondria the most studied organelles in the biomedical sciences. In this review, we will especially focus on certain 'novelties' in mitochondrial biology "left in the shadows" because, although they have been discovered for some time, they are still not taken with due consideration. We will focus on certain particularities of these organelles, for example, those relating to their metabolism and energy efficiency. In particular, some of their functions that reflect the type of cell in which they reside will be critically discussed, for example, the role of some carriers that are strictly functional to the typical metabolism of the cell or to the tissue specialization. Furthermore, some diseases in whose pathogenesis, surprisingly, mitochondria are involved will be mentioned.

Increased metabolism in combination with the novel cytochrome b target-site mutation L258F confers cross-resistance between the Qo inhibitors acequinocyl and bifenazate in Tetranychus urticae

Acequinocyl and bifenazate are potent acaricides acting at the Q_o site of complex III of the electron transport chain, but frequent applications of these acaricides have led to the development of resistance in spider mites. Target-site resistance caused by mutations in the conserved cd1- and ef-helices of the Q_o pocket of cytochrome b has been elucidated as the main resistance mechanism. We therefore monitored Q_o pocket mutations in European field populations of Tetranychus urticae and uncovered a new mutation, L258F. The role of this mutation was validated by revealing patterns of maternal inheritance and by the independently replicated introgression in an unrelated susceptible genetic background. However, the parental strain exhibited higher resistance levels than conferred by the mutation alone in isogenic lines, especially for acequinocyl, implying the involvement of strong additional resistance mechanisms. This was confirmed by revealing a polygenic inheritance pattern with classical genetic crosses and via synergism experiments. Therefore, a genome-wide expression analysis was conducted that identified a number of highly overexpressed detoxification genes, including many P450s. Functional expression revealed that the P450 CYP392A11 can metabolize bifenazate by hydroxylation of the ring structure. In conclusion, the novel cytochrome b target-site mutation L258F was uncovered in a recently collected field strain and its role in acequinocyl and bifenazate resistance was validated. However, the high level of resistance in this strain is most likely caused by a combination of target-site resistance and P450-based increased detoxification, potentially acting in synergism.

Decreased expression of mitochondrial aminoacyl-tRNA synthetases causes downregulation of OXPHOS subunits in type 2 diabetic muscle

Type 2 diabetes mellitus (T2D) affects millions of people worldwide and is one of the leading causes of morbidity and mortality. The skeletal muscle (SKM) is one of the most important tissues involved in maintaining glucose homeostasis and substrate oxidation, and it undergoes insulin resistance in T2D. In this study, we identify the existence of alterations in the expression of mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs) in skeletal muscle from two different forms of T2D: early-onset type 2 diabetes (YT2) (onset of the disease before 30 years of age) and the classical form of the disease (OT2). GSEA analysis from microarray studies revealed the repression of mitochondrial mt-aaRSs independently of age, which was validated by real-time PCR assays. In agreement with this, a reduced expression of several encoding mt-aaRSs was also detected in skeletal muscle from diabetic (db/db) mice but not in obese ob/ob mice. In addition, the expression of the mt-aaRSs proteins most relevant in the synthesis of mitochondrial proteins, threonyl-tRNA, and leucyl-tRNA synthetases (TARS2 and LARS2) were also repressed in muscle from db/db mice. It is likely that these alterations participate in the reduced expression of proteins synthesized in the mitochondria detected in db/db mice. We also document an increased iNOS abundance in mitochondrial-enriched muscle fractions from diabetic mice that may inhibit aminoacylation of TARS2 and LARS2 by nitrosative stress. Our results indicate a reduced expression of mt-aaRSs in skeletal muscle from T2D patients, which may participate in the reduced expression of proteins synthesized in mitochondria. An enhanced mitochondrial iNOS could play a regulatory role in diabetes.

Design and synthesis of photostable triphenylamine based neutral AIE nano luminogens: specific and long-term tracking of mitochondria in cells

With the increasing dependence on fluorescence bioimaging, luminogens with aggregation-induced emission (AIE) properties have gained significant attention due to their excellent photostabilization, minimal photobleaching, high reliability, and superior biocompatibility. Since mitochondria are crucial subcellular organelles in eukaryotic cells with important biological functions, organelle-specific AIE emitters with distinct functions have been highly sought after, but with limited success using simple synthetic methods. Here, we describe a strategy for synthesizing two triphenylamine (TPA) based acrylonitriles, tethered to different donor groups, TPA and phenothiazine (PTZ), respectively, with superior AIE properties using Suzuki coupling. We conducted a systematic and detailed experimental analysis of the structural characteristics of both AIE luminogens, which exhibited excellent photostability, a large Stokes shift, and bright solid-state emission. A cell viability study carried out with F1 and F2 dyes revealed that both luminogens exhibited excellent biocompatibility. Based on fluorescence experiments, F2 displayed excellent AIE characteristics, permeability, biocompatibility, and photostability compared to rhodamine 123, allowing it to selectively stain and track mitochondria in cancer cells over an extended period of time. The Pearson correlation coefficient of F2 and rhodamine 123 was estimated to have an r-value of 0.99. Our findings are expected to provide insight into the synthesis of an extensive archive of AIE-based acrylonitriles with fascinating properties for mitochondrial staining.

The Beneficial Effect of Mitochondrial Transfer Therapy in 5XFAD Mice via Liver–Serum–Brain Response

We recently reported the benefit of the IV transferring of active exogenous mitochondria in a short-term pharmacological AD (Alzheimer’s disease) model. We have now explored the efficacy of mitochondrial transfer in 5XFAD transgenic mice, aiming to explore the underlying mechanism by which the IV-injected mitochondria affect the diseased brain. Mitochondrial transfer in 5XFAD ameliorated cognitive impairment, amyloid burden, and mitochondrial dysfunction. Exogenously injected mitochondria were detected in the liver but not in the brain. We detected alterations in brain proteome, implicating synapse-related processes, ubiquitination/proteasome-related processes, phagocytosis, and mitochondria-related factors, which may lead to the amelioration of disease. These changes were accompanied by proteome/metabolome alterations in the liver, including pathways of glucose, glutathione, amino acids, biogenic amines, and sphingolipids. Altered liver metabolites were also detected in the serum of the treated mice, particularly metabolites that are known to affect neurodegenerative processes, such as carnosine, putrescine, C24:1-OH sphingomyelin, and amino acids, which serve as neurotransmitters or their precursors. Our results suggest that the beneficial effect of mitochondrial transfer in the 5XFAD mice is mediated by metabolic signaling from the liver via the serum to the brain, where it induces protective effects. The high efficacy of the mitochondrial transfer may offer a novel AD therapy.

Key role of mitochondrial mutation Leu107Ser (COX1) in deltamethrin resistance in salmon lice (Lepeophtheirus salmonis)

The pyrethroid deltamethrin (DTM) is used to treat Atlantic salmon (Salmo salar) against salmon louse (Lepeophtheirus salmonis) infestations. However, DTM resistance has evolved in L. salmonis and is currently common in the North Atlantic. This study aimed to re-assess the association between DTM resistance and mitochondrial (mtDNA) mutations demonstrated in previous reports. Among 218 L. salmonis collected in Scotland in 2018–2019, 89.4% showed DTM resistance in bioassays, while 93.6% expressed at least one of four mtDNA single nucleotide polymorphisms (SNPs) previously shown to be resistance associated. Genotyping at further 14 SNP loci allowed to define three resistance-associated mtDNA haplotypes, named 2, 3 and 4, occurring in 72.0%, 14.2% and 7.3% of samples, respectively. L. salmonis strains IoA-02 (haplotype 2) and IoA-10 (haplotype 3) both showed high levels (~ 100-fold) of DTM resistance, which was inherited maternally in crossing experiments. MtDNA haplotypes 2 and 3 differed in genotype for 17 of 18 studied SNPs, but shared one mutation that causes an amino acid change (Leu107Ser) in the cytochrome c oxidase subunit 1 (COX1) and was present in all DTM resistant while lacking in all susceptible parasites. We conclude that Leu107Ser (COX1) is a main genetic determinant of DTM resistance in L. salmonis.

Do Autophagy Enhancers/ROS Scavengers Alleviate Consequences of Mild Mitochondrial Dysfunction Induced in Neuronal-Derived Cells?

Mitochondrial function is at the nexus of pathways regulating synaptic-plasticity and cellular resilience. The involvement of brain mitochondrial dysfunction along with increased reactive oxygen species (ROS) levels, accumulating mtDNA mutations, and attenuated autophagy is implicated in psychiatric and neurodegenerative diseases. We have previously modeled mild mitochondrial dysfunction assumed to occur in bipolar disorder (BPD) using exposure of human neuronal cells (SH-SY5Y) to rotenone (an inhibitor of mitochondrial-respiration complex-I) for 72 and 96 h, which exhibited up- and down-regulation of mitochondrial respiration, respectively. In this study, we aimed to find out whether autophagy enhancers (lithium, trehalose, rapamycin, and resveratrol) and/or ROS scavengers [resveratrol, N-acetylcysteine (NAC), and Mn-Tbap) can ameliorate neuronal mild mitochondrial dysfunction. Only lithium (added for the last 24/48 h of the exposure to rotenone for 72/96 h, respectively) counteracted the effect of rotenone on most of the mitochondrial respiration parameters (measured as oxygen consumption rate (OCR)). Rapamycin, resveratrol, NAC, and Mn-Tbap counteracted most of rotenone's effects on OCR parameters after 72 h, possibly via different mechanisms, which are not necessarily related to their ROS scavenging and/or autophagy enhancement effects. The effect of lithium reversing rotenone's effect on OCR parameters is compatible with lithium's known positive effects on mitochondrial function and is possibly mediated via its effect on autophagy. By-and-large it may be summarized that some autophagy enhancers/ROS scavengers alleviate some rotenone-induced mild mitochondrial changes in SH-SY5Y cells.

Fifteen days of moderate normobaric hypoxia does not affect mitochondrial function, and related genes and proteins, in healthy men

PURPOSE

To investigate within the one study potential molecular and cellular changes associated with mitochondrial biogenesis following 15 days of exposure to moderate hypoxia.

METHODS

Eight males underwent a muscle biopsy before and after 15 days of hypoxia exposure (FiO₂ = 0.140-0.154; ~ 2500-3200 m) in a hypoxic hotel. Mitochondrial respiration, citrate synthase (CS) activity, and the content of genes and proteins associated with mitochondrial biogenesis were investigated.

RESULTS

Our main findings were the absence of significant changes in the mean values of CS activity, mitochondrial respiration in permeabilised fibers, or the content of genes and proteins associated with mitochondrial biogenesis, after 15 days of moderate normobaric hypoxia.

CONCLUSION

Our data provide evidence that 15 days of moderate normobaric hypoxia have negligible influence on skeletal muscle mitochondrial content and function, or genes and proteins content associated with mitochondrial biogenesis, in young recreationally active males. However, the increase in mitochondrial protease LON content after hypoxia exposure suggests the possibility of adaptations to optimise respiratory chain function under conditions of reduced O₂ availability.

Mitochondrial Aminoacyl-tRNA Synthetase and Disease: The Yeast Contribution for Functional Analysis of Novel Variants

In most eukaryotes, mitochondrial protein synthesis is essential for oxidative phosphorylation (OXPHOS) as some subunits of the respiratory chain complexes are encoded by the mitochondrial DNA (mtDNA). Mutations affecting the mitochondrial translation apparatus have been identified as a major cause of mitochondrial diseases. These mutations include either heteroplasmic mtDNA mutations in genes encoding for the mitochondrial rRNA (mtrRNA) and tRNAs (mttRNAs) or mutations in nuclear genes encoding ribosomal proteins, initiation, elongation and termination factors, tRNA-modifying enzymes, and aminoacyl-tRNA synthetases (mtARSs). Aminoacyl-tRNA synthetases (ARSs) catalyze the attachment of specific amino acids to their cognate tRNAs. Differently from most mttRNAs, which are encoded by mitochondrial genome, mtARSs are encoded by nuclear genes and then imported into the mitochondria after translation in the cytosol. Due to the extensive use of next-generation sequencing (NGS), an increasing number of mtARSs variants associated with large clinical heterogeneity have been identified in recent years. Being most of these variants private or sporadic, it is crucial to assess their causative role in the disease by functional analysis in model systems. This review will focus on the contributions of the yeast Saccharomyces cerevisiae in the functional validation of mutations found in mtARSs genes associated with human disorders.

Evolution, systematics, and the unnatural history of mitochondrial DNA

The tenets underlying the use of mtDNA in phylogenetic and systematic analyses are strict maternal inheritance, clonality, homoplasmy, and difference due to mutation: that is, there are species-specific mtDNA sequences and phylogenetic reconstruction is a matter of comparing these sequences and inferring closeness of relatedness from the degree of sequence similarity. Yet, how mtDNA behavior became so defined is mysterious. Even though early studies of fertilization demonstrated for most animals that not only the head, but the sperm's tail and mitochondria-bearing midpiece penetrate the egg, the opposite - only the head enters the egg - became fact, and mtDNA conceived as maternally transmitted. When midpiece/tail penetration was realized as true, the conceptions 'strict maternal inheritance', etc., and their application to evolutionary endeavors, did not change. Yet there is mounting evidence of paternal mtDNA transmission, paternal and maternal combination, intracellular recombination, and intra- and intercellular heteroplasmy. Clearly, these phenomena impact the systematic and phylogenetic analysis of mtDNA sequences.

Assay of Bacillus cereus Emetic toxin produced in orange squash

The contamination of squash by B. cereus, an enterotoxin producer, was found to range between 7.5×104  and 1.8×104 CFU/g in orange squash (during storage), that is hazardous. Orange squash is widely produced and consumed in India, but has a low rating of 3 on the scale of 10 (on feedback), mostly due to high sugars, not preferred these days. It can be preserved for >9 months due to added sugars and preservatives. During processing squash, if juice is not quickly cooled and/or squash is kept for long at temperatures <48 °C after processing, it can be a source of food poisoning. Reason, a large number of toxins can be produced by B. cereus. B. cereus strains, isolated from squash, produce heat stable toxin. Vacuolar assay confirmed them as emetic toxins, produced in squash. The toxin behaved like an ionophore in assay using mitochondria, extracted from liver cells of chicken with potassium ions in buffer. The toxicity of toxin by assay was 3200 IU/ng (BC IV strain) and 800 IU/ng (BC X strain). By the vacuolar expansions of mitochondria in assay, toxins of B. cereus demonstrated a toxic effect, in the range of 20.93 to 60.94 % by BC IV toxin and 43.28 to 45.02 % by BC X toxin, on the 3rd day growth of B. cereus in squash and toxin extraction for assay. It was also possible to produce antibodies against the B. cereus whole cell and toxin of BC IV, as an attempt to detect B. cereus contaminations in foods, by Ouchterlony’s immune-diffusion test

Micro- and Nano-Devices for Studying Subcellular Biology

Cells are complex machines whose behaviors arise from their internal collection of dynamically interacting organelles, supramolecular complexes, and cytoplasmic chemicals. The current understanding of the nature by which subcellular biology produces cell-level behaviors is limited by the technological hurdle of measuring the large number (>103 ) of small-sized (<1 μm) heterogeneous organelles and subcellular structures found within each cell. In this review, the emergence of a suite of micro- and nano-technologies for studying intracellular biology on the scale of organelles is described. Devices that use microfluidic and microelectronic components for 1) extracting and isolating subcellular structures from cells and lysate; 2) analyzing the physiology of individual organelles; and 3) recreating subcellular assembly and functions in vitro, are described. The authors envision that the continued development of single organelle technologies and analyses will serve as a foundation for organelle systems biology and will allow new insight into fundamental and clinically relevant biological questions.

Post-transcriptional control of mitochondrial protein composition in changing environmental conditions

In fluctuating environmental conditions, organisms must modulate their bioenergetic production in order to maintain cellular homeostasis for optimal fitness. Mitochondria are hubs for metabolite and energy generation. Mitochondria are also highly dynamic in their function: modulating their composition, size, density, and the network-like architecture in relation to the metabolic demands of the cell. Here, we review the recent research on the post-transcriptional regulation of mitochondrial composition focusing on mRNA localization, mRNA translation, protein import, and the role that dynamic mitochondrial structure may have on these gene expression processes. As mitochondrial structure and function has been shown to be very important for age-related processes, including cancer, metabolic disorders, and neurodegeneration, understanding how mitochondrial composition can be affected in fluctuating conditions can lead to new therapeutic directions to pursue.

Mitochondrial Transfer Ameliorates Cognitive Deficits, Neuronal Loss, and Gliosis in Alzheimer's Disease Mice

Pathogenesis of neurodegenerative diseases involves dysfunction of mitochondria, one of the most important cell organelles in the brain, with its most prominent roles in producing energy and regulating cellular metabolism. Here we investigated the effect of transferring active intact mitochondria as a potential therapy for Alzheimer's disease (AD), in order to correct as many mitochondrial functions as possible, rather than a mono-drug related therapy. For this purpose, AD-mice (amyloid-β intracerebroventricularly injected) were treated intravenously (IV) with fresh human isolated mitochondria. One to two weeks later, a significantly better cognitive performance was noticed in the mitochondria treated AD-mice relative to vehicle treated AD-mice, approaching the performance of non-AD mice. We also detected a significant decrease in neuronal loss and reduced gliosis in the hippocampus of treated mice relative to untreated AD-mice. An amelioration of the mitochondrial dysfunction in brain was noticed by the increase of citrate-synthase and cytochrome c oxidase activities relative to untreated AD-mice, reaching activity levels of non-AD-mice. Increased mitochondrial activity was also detected in the liver of mitochondria treated mice. No treatment-related toxicity was noted. Thus, IV mitochondrial transfer may possibly offer a novel therapeutic approach for AD.

l-Arginine Inhibits Apoptosis of Ovine Intestinal Epithelial Cells through the l-Arginine-Nitric Oxide Pathway

BACKGROUND

In nonruminants, many of the biological roles of l-arginine (Arg) at the intestinal level are mediated through the Arg-nitric oxide (Arg-NO) pathway. Whether the Arg-NO pathway is involved in controlling the immune response and viability in ovine intestinal epithelial cells (IOECs) is unclear.

OBJECTIVES

The current study aimed to examine the role of the Arg-NO pathway in apoptosis, antioxidant capacity, and mitochondrial function of IOECs.

METHODS

The IOECs were incubated in Arg-free DMEM supplemented with 150 μM Arg (CON) or 300 μM Arg (ARG) alone or with 350 μM Nw-nitro-l-arginine methyl ester hydrochloride (l-NAME) (CON + NAME, ARG + NAME) for 24 h. The reactive oxygen species (ROS) concentration, antioxidant capacity, and cell apoptotic percentage were determined.

RESULTS

Arg supplementation decreased (P < 0.05) the ROS concentration (38.9% and 22.7%) and apoptotic cell percentage (57.2% and 54.8%) relative to the CON and CON + NAME groups, respectively. Relative to the CON and ARG treatments, the l-NAME administration decreased (P < 0.05) the mRNA abundance of superoxide dismutase 2 (32% and 21.3%, respectively) and epithelial NO synthase (36% and 29.1%, respectively). Arg supplementation decreased (P < 0.05) the protein abundance of apoptosis antigen 1 (FAS) (52.0% and 43.9%) but increased (P < 0.05) those of nuclear respiratory factor 1 (31.3% and 22.9%) and inducible NO synthase (35.2% and 41.8%) relative to the CON and CON + NAME groups, respectively.

CONCLUSIONS

The inhibition of apoptosis in IOECs due to the increased supply of Arg is associated with the mitochondria- and FAS-dependent pathways through the activity of the Arg-NO pathway. The findings help elucidate the role of the Arg-NO pathway in IOEC growth and apoptosis.

The efficiency of universal mitochondrial DNA barcodes for species discrimination of Pomacea canaliculata and Pomacea maculata

Invasive apple snails, Pomacea canaliculata and P. maculata, have a widespread distribution globally and are regarded as devastating pests of agricultural wetlands. The two species are morphologically similar, which hinders species identification via morphological approaches and species-specific management efforts. Advances in molecular genetics may contribute effective diagnostic tools to potentially resolve morphological ambiguity. DNA barcoding has revolutionized the field of taxonomy by providing an alternative, simple approach for species discrimination, where short sections of DNA, the cytochrome c oxidase subunit I (COI) gene in particular, are used as ‘barcodes’ to delineate species boundaries. In our study, we aimed to assess the effectiveness of two mitochondrial markers, the COI and 16S ribosomal deoxyribonucleic acid (16S rDNA) markers for DNA barcoding of P. canaliculata and P. maculata. The COI and 16S rDNA sequences of 40 Pomacea specimens collected from six localities in Peninsular Malaysia were analyzed to assess their barcoding performance using phylogenetic methods and distance-based assessments. The results confirmed both markers were suitable for barcoding P. canaliculata and P. maculata. The phylogenies of the COI and 16S rDNA markers demonstrated species-specific monophyly and were largely congruent with the exception of one individual. The COI marker exhibited a larger barcoding gap (6.06–6.58%) than the 16S rDNA marker (1.54%); however, the magnitude of barcoding gap generated within the barcoding region of the 16S rDNA marker (12-fold) was bigger than the COI counterpart (approximately 9-fold). Both markers were generally successful in identifying P. canaliculata and P. maculata in the similarity-based DNA identifications. The COI + 16S rDNA concatenated dataset successfully recovered monophylies of P. canaliculata and P. maculata but concatenation did not improve individual datasets in distance-based analyses. Overall, although both markers were successful for the identification of apple snails, the COI molecular marker is a better barcoding marker and could be utilized in various population genetic studies of P. canaliculata and P. maculata.

Oncogenic pathways and the electron transport chain: a dangeROS liaison

Driver mutations in oncogenic pathways, rewiring of cellular metabolism and altered ROS homoeostasis are intimately connected hallmarks of cancer. Electrons derived from different metabolic processes are channelled into the mitochondrial electron transport chain (ETC) to fuel the oxidative phosphorylation process. Electrons leaking from the ETC can prematurely react with oxygen, resulting in the generation of reactive oxygen species (ROS). Several signalling pathways are affected by ROS, which act as second messengers controlling cell proliferation and survival. On the other hand, oncogenic pathways hijack the ETC, enhancing its ROS-producing capacity by increasing electron flow or by impinging on the structure and organisation of the ETC. In this review, we focus on the ETC as a source of ROS and its modulation by oncogenic pathways, which generates a vicious cycle that resets ROS levels to a higher homoeostatic set point, sustaining the cancer cell phenotype.

A new insight into the molecular hydrogen effect on coenzyme Q and mitochondrial function of rats

Mitochondria are the major source of cellular energy metabolism. In the cardiac cells, mitochondria produce by way of the oxidative phosphorylation more than 90% of the energy supply in the form of ATP, which is utilized in many ATP-dependent processes, like cycling of the contractile proteins or maintaining ion gradients. Reactive oxygen species (ROS) are by-products of cellular metabolism and their levels are controlled by intracellular antioxidant systems. Imbalance between ROS and the antioxidant defense leads to oxidative stress and oxidative changes to cellular biomolecules. Molecular hydrogen (H₂) has been proved as beneficial in the prevention and therapy of various diseases including cardiovascular disorders. It selectively scavenges hydroxyl radical and peroxynitrite, reduces oxidative stress, and has anti-inflammatory and anti-apoptotic effects. The effect of H₂ on the myocardial mitochondrial function and coenzyme Q levels is not well known. In this paper, we demonstrated that consumption of H₂-rich water (HRW) resulted in stimulated rat cardiac mitochondrial electron respiratory chain function and increased levels of ATP production by Complex I and Complex II substrates. Similarly, coenzyme Q₉ levels in the rat plasma, myocardial tissue, and mitochondria were increased and malondialdehyde level in plasma was reduced after HRW administration. Based on obtained data, we hypothesize a new metabolic pathway of the H₂ effect in mitochondria on the Q-cycle and in mitochondrial respiratory chain function. The Q-cycle contains three coenzyme Q forms: coenzyme Q in oxidized form (ubiquinone), radical form (semiquinone), or reduced form (ubiquinol). H₂ may be a donor of both electron and proton in the Q-cycle and thus we can suppose stimulation of coenzyme Q production. When ubiquinone is reduced to ubiquinol, lipid peroxidation is reduced. Increased CoQ₉ concentration can stimulate electron transport from Complex I and Complex II to Complex III and increase ATP production via mitochondrial oxidative phosphorylation. Our results indicate that H₂ may function to prevent/treat disease states with disrupted myocardial mitochondrial function.

Acute Respiratory Failure Is the Initial Manifestation in the Adult-Onset A3243G tRNALeu mtDNA Mutation: A Case Report and the Literature Review

Isolated mitochondrial myopathy refers to the condition of mitochondrial disorders that primarily affect the skeletal muscle system. Here we report on a case of a patient who presented with acute respiratory failure as the initial and predominant clinical manifestation after using anesthetic drugs. The diagnosis of mitochondrial myopathy was made by histochemical findings of ragged red fibers with a modified Gomori trichrome Stain in the skeletal muscle biopsy and the genetic detection of an A3243G point mutation in the tRNA^Leu (UUR) gene of mitochondrial DNA (mtDNA) in a peripheral blood specimen. The patient revealed a benign clinical outcome with ventilator assistance and a cocktail treatment. Further, we performed a literature review on patients with respiratory failure as the early and predominant manifestation in adult-onset isolated mitochondrial myopathy. Eleven cases in nine studies (including our case) have been reported, and five of whom underwent DNA analysis all harbored the A3243G mutation in the tRNA^Leu gene of the mtDNA. Use of sedative drugs tends to induce acute respiratory failure in such cases.

Multi-Faceted Role of Melatonin in Neuroprotection and Amelioration of Tau Aggregates in Alzheimer's Disease

Alzheimer's disease (AD) is one of the major age related neurodegenerative diseases whose pathology arises due to the presence of two distinct protein aggregates, viz., amyloid-β plaques in extracellular matrix and tau neurofibrillary tangles in neurons. Multiple factors play a role in AD pathology, which includes familial mutations, oxidative stress, and post-translational modifications. Melatonin is an endocrine hormone, secreted during darkness, derived from tryptophan, and produced mainly by the pineal gland. It is an amphipathic molecule, which makes it suitable to cross not only blood-brain barrier, but also to enter several other subcellular compartments like mitochondria and endoplasmic reticulum. In this context, the neuroprotective effect of melatonin may be attributed to its role as an antioxidant. Melatonin's pleiotropic function as an antioxidant and neuroprotective agent has been widely studied. However, its direct effect on the aggregation of tau and amyloid-β needs to be explored. Furthermore, an important aspect of its function is its ability to regulate the process of phosphorylation of tau by affecting the function of kinases and phosphatases. In this review, we are focusing on the pleiotropic function of melatonin on the aspect of its neuroprotective function in tau pathology, which includes antioxidant function, regulation of enzymes, including kinases and enzymes involved in free radical scavenging and mitochondrial protection.

From nutritional wealth to autophagy: In vivo metabolic dynamics in the cytosol, mitochondrion and shuttles of IgG producing CHO cells

To fulfil the optimization needs of current biopharmaceutical processes the knowledge how to improve cell specific productivities is of outmost importance. This requires a detailed understanding of cellular metabolism on a subcellular level inside compartments such as cytosol and mitochondrion. Using IgG1 producing Chinese hamster ovary (CHO) cells, a pioneering protocol for compartment-specific metabolome analysis was applied. Various production-like growth conditions ranging from ample glucose and amino acid supply via moderate to severe nitrogen limitation were investigated in batch cultures. The combined application of quantitative metabolite pool analysis, ¹³C tracer studies and non-stationary flux calculations revealed that Pyr/H⁺ symport (MPC1/2) bore the bulk of the mitochondrial transport under ample nutrient supply. Glutamine limitation induced the concerted adaptation of the bidirectional Mal/aKG (OGC) and the Mal/HPO₄^2- antiporter (DIC), even installing completely reversed shuttle fluxes. As a result, NADPH and ATP formation were adjusted to cellular needs unraveling the key role of cytosolic malic enzyme for NADPH production. Highest cell specific IgG1 productivities were closely correlated to a strong mitochondrial malate export according to the anabolic demands. The requirement to install proper NADPH supply for optimizing the production of monoclonal antibodies is clearly outlined. Interestingly, it was observed that mitochondrial citric acid cycle activity was always maintained enabling constant cytosolic adenylate energy charges at physiological levels, even under autophagy conditions.

Uncoupling Effect of F16 Is Responsible for Its Mitochondrial Toxicity and Anticancer Activity

As a novel delocalized lipophilic cation, F16 selectively accumulates in mitochondria of carcinoma cells and shows a broad spectrum of antiproliferative action towards cancer cell lines. In order to reveal the mode of action and molecular mechanism of F16 inducing cytotoxicity, we investigated the effects of F16 on cancer cells and isolated mitochondria relative to its precursor compound (E)-3-(2-(pyridine-4yl)vinyl)-1 H-indole (PVI), which has a similar structure without positive charge. It was found that PVI did not accumulate in mitochondria, and exhibited lower cytotoxicity compared to F16. However, when they were directly incubated with mitochondria, both F16 and PVI were observed to induce damage to mitochondrial structure and function. Moreover, it was found that F16 as well as PVI acted as uncouplers on mitochondria, and further rescue experiments revealed that the addition of adenosine 5'-triphosphate was the most effective way to recover the cell viability decreased by F16. Thus it was concluded that the decreased intracellular adenosine 5'-triphosphate availability induced by the uncoupling effect of F16 was a major factor in F16-mediated cytotoxicity. Futhermore, the results indicated that the uncoupling effect of F16 is attributed to its chemical stucture in common with PVI but independent of its positive charge. The study may shed light on understanding the underlying mechanism of action for F16, and providing suggestions for the design of new mitochondria-targeted antitumor molecules.

A Proteomic Analysis of Mitochondrial Complex III Inhibition in SH-SY5Y Human Neuroblastoma Cell Line

Methods:

We treated SH-SY5Y neuroblastoma cells with AntA in order to establish an in vitro mitochondrial dysfunction model for HD. Differential proteome analysis was performed by the nLCMS/ MS system. Protein expression was assessed by western blot analysis.

Results:

Thirty five differentially expressed proteins as compared to the vehicle-treated controls were detected. Functional pathway analysis indicated that proteins involved in ubiquitin-proteasomal pathway were up-regulated in AntA-treated SH-SY5Y neuroblastoma cells and the ubiquitinated protein accumulation was confirmed by immunoblotting. We found that Prothymosin α (ProT α) was downregulated. Furthermore, we demonstrated that nuclear factor erythroid 2-related factor 2 (Nrf2) protein expression was co-regulated with ProT α expression, hence knockdown of ProT α in SH-SY5Y cells decreased Nrf2 protein level.

Conclusion:

Our findings suggest that complex III impairment might downregulate ubiquitinproteasome function and NRF2/Keap1 antioxidant response. In addition, it is likely that downregulation of Nrf2 is due to the decreased expression of ProT α in AntA-treated SH-SY5Y cells. Our results could advance the understanding of mechanisms involved in neurodegenerative diseases.

Mutant MRPS5 affects mitoribosomal accuracy and confers stress-related behavioral alterations

The 1555 A to G substitution in mitochondrial 12S A‐site rRNA is associated with maternally transmitted deafness of variable penetrance in the absence of otherwise overt disease. Here, we recapitulate the suggested A1555G‐mediated pathomechanism in an experimental model of mitoribosomal mistranslation by directed mutagenesis of mitoribosomal protein MRPS5. We first establish that the ratio of cysteine/methionine incorporation and read‐through of mtDNA‐encoded MT‐CO1 protein constitute reliable measures of mitoribosomal misreading. Next, we demonstrate that human HEK293 cells expressing mutant V336Y MRPS5 show increased mitoribosomal mistranslation. As for immortalized lymphocytes of individuals with the pathogenic A1555G mutation, we find little changes in the transcriptome of mutant V336Y MRPS5 HEK cells, except for a coordinated upregulation of transcripts for cytoplasmic ribosomal proteins. Homozygous knock‐in mutant Mrps5 V338Y mice show impaired mitochondrial function and a phenotype composed of enhanced susceptibility to noise‐induced hearing damage and anxiety‐related behavioral alterations. The experimental data in V338Y mutant mice point to a key role of mitochondrial translation and function in stress‐related behavioral and physiological adaptations.

The Oxidative Stress and Mitochondrial Dysfunction during the Pathogenesis of Diabetic Retinopathy

Diabetic retinopathy is one of the most serious microvascular complications induced by hyperglycemia via five major pathways, including polyol, hexosamine, protein kinase C, and angiotensin II pathways and the accumulation of advanced glycation end products. The hyperglycemia-induced overproduction of reactive oxygen species (ROS) induces local inflammation, mitochondrial dysfunction, microvascular dysfunction, and cell apoptosis. The accumulation of ROS, local inflammation, and cell death are tightly linked and considerably affect all phases of diabetic retinopathy pathogenesis. Furthermore, microvascular dysfunction induces ischemia and local inflammation, leading to neovascularization, macular edema, and neurodysfunction, ultimately leading to long-term blindness. Therefore, it is crucial to understand and elucidate the detailed mechanisms underlying the development of diabetic retinopathy. In this review, we summarized the existing knowledge about the pathogenesis and current strategies for the treatment of diabetic retinopathy, and we believe this systematization will help and support further research in this area.

Three human aminoacyl-tRNA synthetases have distinct sub-mitochondrial localizations that are unaffected by disease-associated mutations

Human mitochondrial aminoacyl-tRNA synthetases (mt-aaRSs) are key enzymes in the mitochondrial protein translation system and catalyze the charging of amino acids on their cognate tRNAs. Mutations in their nuclear genes are associated with pathologies having a broad spectrum of clinical phenotypes, but with no clear molecular mechanism(s). For example, mutations in the nuclear genes encoding mt-AspRS and mt-ArgRS are correlated with the moderate neurodegenerative disorder leukoencephalopathy with brainstem and spinal cord involvement and lactate elevation (LBSL) and with the severe neurodevelopmental disorder pontocerebellar hypoplasia type 6 (PCH6), respectively. Previous studies have shown no or only minor impacts of these mutations on the canonical properties of these enzymes, indicating that the role of the mt-aaRSs in protein synthesis is mostly not affected by these mutations, but their effects on the mitochondrial localizations of aaRSs remain unclear. Here, we demonstrate that three human aaRSs, mt-AspRS, mt-ArgRS, and LysRS, each have a specific sub-mitochondrial distribution, with mt-ArgRS being exclusively localized in the membrane, LysRS exclusively in the soluble fraction, and mt-AspRS being present in both. Chemical treatments revealed that mt-AspRs is anchored in the mitochondrial membrane through electrostatic interactions, whereas mt-ArgRS uses hydrophobic interactions. We also report that novel mutations in mt-AspRS and mt-ArgRS genes from individuals with LBSL and PCH6, respectively, had no significant impact on the mitochondrial localizations of mt-AspRS and mt-ArgRS. The variable sub-mitochondrial locations for these three mt-aaRSs strongly suggest the existence of additional enzyme properties, requiring further investigation to unravel the mechanisms underlying the two neurodegenerative disorders.

Whole-genome RNAi screen identifies methylation-related genes influencing lipid metabolism in Caenorhabditis elegans

Lipid droplets (LDs) are highly conserved multifunctional cellular organelles and aberrant lipid storage in LDs can lead to many metabolic diseases. However, the molecular mechanisms governing lipid dynamic changes remain elusive, and the high-throughput screen of genes influencing LD morphology was limited by lacking specific LD marker proteins in the powerful genetic tool Caenorhabditis elegans. In this study, we established a new method to conduct whole-genome RNAi screen using LD resident protein DHS-3 as a LD marker, and identified 78 genes involved in significant LD morphologic changes. Among them, mthf-1, as well as a series of methylation-related genes, was found dramatically influencing lipid metabolism. SREBP-1 and SCD1 homologs in C. elegans were involved in the lipid metabolic change of mthf-1(RNAi) worms, and the regulation of ATGL-1 also contributed to it by decreasing triacylglycerol (TAG) hydrolysis. Overall, this study not only identified important genes involved in LD dynamics, but also provided a new tool for LD study using C. elegans, with implications for the study of lipid metabolic diseases.

Mitochondrial morphology and function impaired by dimethyl sulfoxide and dimethyl Formamide

In this work, the effects of two non-ionic, non-hydroxyl organic solvents, dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) on the morphology and function of isolated rat hepatic mitochondria were investigated and compared. Mitochondrial ultrastructures impaired by DMSO and DMF were clearly observed by transmission electron microscopy. Spectroscopic and polarographic results demonstrated that organic solvents induced mitochondrial swelling, enhanced the permeation to H⁺/K⁺, collapsed the potential inner mitochondrial membrane (IMM), and increased the IMM fluidity. Moreover, with organic solvents addition, the outer mitochondrial membrane (OMM) was broken, accompanied with the release of Cytochrome c, which could activate cell apoptosis signaling pathway. The role of DMSO and DMF in enhancing permeation or transient water pore formation in the mitochondrial phospholipid bilayer might be the main reason for the mitochondrial morphology and function impaired. Mitochondrial dysfunctions induced by the two organic solvents were dose-dependent, but the extents varied. Ethanol (EtOH) showed the highest potential damage on the mitochondrial morphology and functions, followed by DMF and DMSO.

Silver ion-induced mitochondrial dysfunction via a nonspecific pathway

Silver, once regarded as a safe noble metal for humans, has been widely used in industrial and commercial products, especially in nanometer biomaterials. It is now well known that Ag+ is biologically active and is able to interact with the cell membrane, proteins and DNA. However, very little is understood about the potential impacts of Ag+ at the sub-cellular level. Our work investigated the potential toxicity of Ag+ on mitochondria isolated from rat livers by examining the mitochondrial morphology, respiration, swelling, membrane fluidity and reactive oxygen species (ROS) generation. We observed that Ag+ significantly affects the mitochondrial structure and function, including mitochondrial swelling, collapse of the transmembrane potential, change of permeability and fluidity, decline of the respiratory rate, and acceleration of ROS, indicating that Ag+ should be seriously regarded as a potentially hazardous substance. Moreover, we conclude that Ag+ injures the mitochondrial structure and function by a nonspecific approach, in which the interaction is unregulated by inherent parts such as the mitochondria permeability transition pore (MPTP). These results help us learn more about the toxicity of Ag+ at the subcellular (mitochondrial) level and influence future biological and medical applications of Ag-based materials.

Testosterone Upregulates the Expression of Mitochondrial ND1 and ND4 and Alleviates the Oxidative Damage to the Nigrostriatal Dopaminergic System in Orchiectomized Rats

Testosterone deficiency, as a potential risk factor for aging and aging-related neurodegenerative disorders, might induce mitochondrial dysfunction and facilitate the declines of the nigrostriatal dopaminergic system by exacerbating the mitochondrial defects and increasing the oxidative damage. Thus, how testosterone levels influence the mitochondrial function in the substantia nigra was investigated in the study. The present studies showed that testosterone deficiency impaired the mitochondrial function in the substantia nigra and induced the oxidative damage to the substantia nigra as well as the deficits in the nigrostriatal dopaminergic system. Of four mitochondrial respiratory chain complexes, castration of male rats reduced the activity of mitochondrial complex I and downregulated the expression of ND1 and ND4 of 7 mitochondrial DNA- (mtDNA-) encoded subunits of complex I in the substantia nigra. Supplements of testosterone propionate to castrated male rats ameliorated the activity of mitochondrial complex I and upregulated the expression of mitochondrial ND1 and ND4. These results suggest an important role of testosterone in maintaining the mitochondrial function in the substantia nigra and the vulnerability of mitochondrial complex I to testosterone deficiency. Mitochondrial ND1 and ND4, as potential testosterone targets, were implicated in the oxidative damage to the nigrostriatal dopaminergic system.

Mitochondria-Derived Damage-Associated Molecular Patterns in Neurodegeneration

Inflammation is increasingly implicated in neurodegenerative disease pathology. As no acquired pathogen appears to drive this inflammation, the question of what does remains. Recent advances indicate damage-associated molecular pattern (DAMP) molecules, which are released by injured and dying cells, can cause specific inflammatory cascades. Inflammation, therefore, can be endogenously induced. Mitochondrial components induce inflammatory responses in several pathological conditions. Due to evidence such as this, a number of mitochondrial components, including mitochondrial DNA, have been labeled as DAMP molecules. In this review, we consider the contributions of mitochondrial-derived DAMPs to inflammation observed in neurodegenerative diseases.

Relative Quantification of Phospholipids Based on Isotope-Labeled Methylation by Nanoflow Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectrometry: Enhancement in Cardiolipin Profiling

In this study, lipid analysis based on isotope-labeled methlylation (ILM) was performed by nanoflow ultrahigh performance liquid chromatography-eletrospray ionization-tandem mass spectrometry (nUPLC-ESI-MS/MS) for enhanced detection and quantification of targeted phospholipids. ILM depends on methylation of phosphate groups by (trimethylsilyl)diazomethane, and the ILM based quantitation with reversed phase nUPLC-ESI-MS/MS provides advantages in PL profiling such as enhanced detectability of methylated PLs owing to increased hydrophobicity and substantial increase in resolution due to the increase of retention. Efficacy of ILM in nUPLC-ESI-MS/MS analysis was evaluated in the selected reaction monitoring (SRM) method by varying the mixing ratio of H-/D-methylated PL standards, which resulted in the successful quantification of 24 species, including phosphatidic acid (PA), phosphatidylserine (PS), phosphatidylglycerol (PG), ceramide-1-phosphate (Cer1P), phosphoinositides, and cardiolipin (CL), with ∼6.6% variation in the calculated ratio of H-/D-methylated PLs. The method was applied to the lipid extracts from a DU145 cell line after D-allose treatment, resulting in the quantification of 83 PLs of which results were not statistically different from those obtained by conventional quantification methods. Morever, detection and quantification of CLs and PAs were evidenced to be highly effective when used with the ILM method as 43 CLs and 20 PAs from cellular lipid extracts were analyzed while only 18 CLs and 12 PAs were identified when conventional methods were carried out. This proves the ILM combined with LC-MS to be a promising method for analysis of the aforementioned classes of lipids. Overall, the study highlighted the applicability of targeted quantification by the ILM method in lipidomic analysis and demonstrated an improvement in the detection of less abundant anionic PLs.

Allopregnanolone and its analog BR 297 rescue neuronal cells from oxidative stress-induced death through bioenergetic improvement

Allopregnanolone (AP) is supposed to exert beneficial actions including anxiolysis, analgesia, neurogenesis and neuroprotection. However, although mitochondrial dysfunctions are evidenced in neurodegenerative diseases, AP actions against neurodegeneration-induced mitochondrial deficits have never been investigated. Also, the therapeutic exploitation of AP is limited by its difficulty to pass the liver and its rapid clearance after sulfation or glucuronidation of its 3-hydroxyl group. Therefore, the characterization of novel potent neuroprotective analogs of AP may be of great interest. Thus, we synthesized a set of AP analogs (ANS) and investigated their ability to counteract APP-overexpression-evoked bioenergetic deficits and to protect against oxidative stress-induced death of control and APP-transfected SH-SY5Y cells known as a reliable cellular model of Alzheimer's disease (AD). Especially, we examined whether ANS were more efficient than AP to reduce mitochondrial dysfunctions or bioenergetic decrease leading to neuronal cell death. Our results showed that the ANS BR 297 exhibits notable advantages over AP with regards to both protection of mitochondrial functions and reduction of oxidative stress. Indeed, under physiological conditions, BR 297 does not promote cell proliferation but efficiently ameliorates the bioenergetics by increasing cellular ATP level and mitochondrial respiration. Under oxidative stress situations, BR 297 treatment, which decreases ROS levels, improves mitochondrial respiration and cell survival, appears more potent than AP to protect control and APP-transfected cells against H₂O₂-induced death. Our findings lend further support to the neuroprotective effects of BR 297 emphasizing this analog as a promising therapeutic tool to counteract age- and AD-related bioenergetic deficits.

Phosphocreatine protects against LPS-induced human umbilical vein endothelial cell apoptosis by regulating mitochondrial oxidative phosphorylation

Phosphocreatine (PCr) is an exogenous energy substance, which provides phosphate groups for adenosine triphosphate (ATP) cycle and promotes energy metabolism in cells. However, it is still unclear whether PCr has influenced on mitochondrial energy metabolism as well as oxidative phosphorylation (OXPHO) in previous studies. Therefore, the aim of the present study was to investigate the regulation of PCr on lipopolsaccharide (LPS)-induced human umbilical vein endothelial cells (HUVECs) and mitochondrial OXPHO pathway. PCr protected HUVECs against LPS-induced apoptosis by suppressing the mitochondrial permeability transition, cytosolic release of cytochrome c (Cyt C), Ca(2+), reactive oxygen species and subsequent activation of caspases, and increasing Bcl2 expression, while suppressing Bax expression. More importantly, PCr significantly improved mitochondrial swelling and membrane potential, enhanced the activities of ATP synthase and mitochondrial creatine kinase (CKmt) in creatine shuttle, influenced on respiratory chain enzymes, respiratory control ratio, phosphorus/oxygen ratio and ATP production of OXPHO. Above PCr-mediated mitochondrial events were effectively more favorable to reduced form of flavin adenine dinucleotide (FADH2) pathway than reduced form of nicotinamide-adenine dinucleotid pathway in the mitochondrial respiratory chain. Our results revealed that PCr protects against LPS-induced HUVECs apoptosis, which probably related to stabilization of intracellular energy metabolism, especially for FADH2 pathway in mitochondrial respiratory chain, ATP synthase and CKmt. Our findings suggest that PCr may play a certain role in the treatment of atherosclerosis via protecting endothelial cell function.

Exercise-induced rhabdomyolysis mechanisms and prevention: A literature review

Exercise-induced rhabdomyolysis (exRML), a pathophysiological condition of skeletal muscle cell damage that may cause acute renal failure and in some cases death. Increased Ca²⁺ level in cells along with functional degradation of cell signaling system and cell matrix have been suggested as the major pathological mechanisms associated with exRML. The onset of exRML may be exhibited in athletes as well as in general population. Previous studies have reported that possible causes of exRML were associated with excessive eccentric contractions in high temperature, abnormal electrolytes balance, and nutritional deficiencies possible genetic defects. However, the underlying mechanisms of exRML have not been clearly established among health professionals or sports medicine personnel. Therefore, we reviewed the possible mechanisms and correlated prevention of exRML, while providing useful and practical information for the athlete and general exercising population.

A combined in vitro approach to improve the prediction of mitochondrial toxicants

Drug induced mitochondrial dysfunction has been implicated in organ toxicity and the withdrawal of drugs or black box warnings limiting their use. The development of highly specific and sensitive in vitro assays in early drug development would assist in detecting compounds which affect mitochondrial function. Here we report the combination of two in vitro assays for the detection of drug induced mitochondrial toxicity. The first assay measures cytotoxicity after 24h incubation of test compound in either glucose or galactose conditioned media (Glu/Gal assay). Compounds with a greater than 3-fold toxicity in galactose media compared to glucose media imply mitochondrial toxicity. The second assay measures mitochondrial respiration, glycolysis and a reserve capacity with mechanistic responses observed within one hour following exposure to test compound. In order to assess these assays a total of 72 known drugs and chemicals were used. Dose-response data was normalised to 100× Cmax giving a specificity, sensitivity and accuracy of 100%, 81% and 92% respectively for this combined approach.