Regulation of mitochondrial respiration and apoptosis through cell signaling: cytochrome c oxidase and cytochrome c in ischemia/reperfusion injury and inflammation

Mori Ramulus Inhibits Pancreatic β-Cell Apoptosis and Prevents Insulin Resistance by Restoring Hepatic Mitochondrial Function

Type 2 diabetes mellitus is characterized by insulin resistance and pancreatic beta (β)-cell dysfunction. Accumulating evidence suggests that mitochondrial dysfunction may cause insulin resistance in peripheral tissues. As commercial hypoglycemic drugs have side effects, it is necessary to develop safe and effective natural compound-based hypoglycemic treatments. This study aimed to investigate the hypoglycemic effects of Mori Ramulus ethanol extract (ME) in a high-fat diet (HFD)-induced diabetes mouse model to decipher the underlying mechanisms focusing on apoptosis and mitochondrial function. ME significantly decreased tunicamycin-induced apoptotic cell death and increased insulin secretion following glucose stimulation in NIT-1 pancreatic β-cells. Tunicamycin-exposed NIT-1 pancreatic β-cells showed elevated reactive oxygen species levels and reduced mitochondrial membrane potential, which were reversed by ME treatment. ME inhibited the tunicamycin-induced apoptosis cascade in tunicamycin-exposed NIT-1 pancreatic β-cells. In HFD diabetic mice, the serum-free fatty acid and insulin levels decreased following a 15-week ME administration. Glucose and insulin tolerance tests showed that ME improved insulin sensitivity. Moreover, ME ameliorated pancreatic β-cell mass loss in diabetic mice. Finally, ME-treated HFD-fed mice showed improved hepatic mitochondrial function resulting in insulin sensitivity in target tissues. Thus, ME provides protection against pancreatic β-cell apoptosis and prevents insulin resistance by improving mitochondrial function.

Regulation of Cytochrome c Oxidase by Natural Compounds Resveratrol, (-)-Epicatechin, and Betaine

Numerous naturally occurring molecules have been studied for their beneficial health effects. Many compounds have received considerable attention for their potential medical uses. Among them, several substances have been found to improve mitochondrial function. This review focuses on resveratrol, (–)-epicatechin, and betaine and summarizes the published data pertaining to their effects on cytochrome c oxidase (COX) which is the terminal enzyme of the mitochondrial electron transport chain and is considered to play an important role in the regulation of mitochondrial respiration. In a variety of experimental model systems, these compounds have been shown to improve mitochondrial biogenesis in addition to increased COX amount and/or its enzymatic activity. Given that they are inexpensive, safe in a wide range of concentrations, and effectively improve mitochondrial and COX function, these compounds could be attractive enough for possible therapeutic or health improvement strategies.

Anopheles coluzzii stearoyl-CoA desaturase is essential for adult female survival and reproduction upon blood feeding

Vitellogenesis and oocyte maturation require anautogenous female Anopheles mosquitoes to obtain a bloodmeal from a vertebrate host. The bloodmeal is rich in proteins that are readily broken down into amino acids in the midgut lumen and absorbed by the midgut epithelial cells where they are converted into lipids and then transported to other tissues including ovaries. The stearoyl-CoA desaturase (SCD) plays a pivotal role in this process by converting saturated (SFAs) to unsaturated (UFAs) fatty acids; the latter being essential for maintaining cell membrane fluidity amongst other housekeeping functions. Here, we report the functional and phenotypic characterization of SCD1 in the malaria vector mosquito Anopheles coluzzii. We show that RNA interference (RNAi) silencing of SCD1 and administration of sterculic acid (SA), a small molecule inhibitor of SCD1, significantly impact on the survival and reproduction of female mosquitoes following blood feeding. Microscopic observations reveal that the mosquito thorax is quickly filled with blood, a phenomenon likely caused by the collapse of midgut epithelial cell membranes, and that epithelial cells are depleted of lipid droplets and oocytes fail to mature. Transcriptional profiling shows that genes involved in protein, lipid and carbohydrate metabolism and immunity-related genes are the most affected by SCD1 knock down (KD) in blood-fed mosquitoes. Metabolic profiling reveals that these mosquitoes exhibit increased amounts of saturated fatty acids and TCA cycle intermediates, highlighting the biochemical framework by which the SCD1 KD phenotype manifests as a result of a detrimental metabolic syndrome. Accumulation of SFAs is also the likely cause of the potent immune response observed in the absence of infection, which resembles an auto-inflammatory condition. These data provide insights into mosquito bloodmeal metabolism and lipid homeostasis and could inform efforts to develop novel interventions against mosquito-borne diseases.

Female mosquitoes can become infected with malaria parasites upon ingestion of blood from an infected person and can transmit the disease when they bite another person some days later. The bloodmeal is rich in proteins which female mosquitoes use to develop their eggs after converting them first to saturated and then to unsaturated fatty acids inside their gut cells. Here, we present the characterization of the enzyme that mosquitoes use to convert saturated to unsaturated fatty acids and show that when this enzyme is eliminated or inhibited mosquitoes cannot produce eggs and die soon after they feed on blood. The mosquito death appears to be primarily associated with the collapse of their gut epithelial barrier due to the loss of cell membrane integrity, leading to their inner body cavity being filled with the ingested blood. These mosquitoes also suffer from an acute and detrimental auto-inflammatory condition due to mounting of a potent immune response in the absence of any infection. We conclude that this enzyme and the mechanism of converting blood-derived proteins to unsaturated fatty acids as a whole can be a good target of interventions aiming at limiting the mosquito abundance and blocking malaria transmission.

Tetrahydroxystilbene glucoside protects against sodium azide-induced mitochondrial dysfunction in human neuroblastoma cells

Objective

Mitochondrial dysfunction is evident in the early stage of Alzheimer’s disease (AD). Therefore development of drugs that protect mitochondrial function is a promising strategy for AD. The present work was to investigate the effects of 2, 3, 5, 4′-Tetrahydroxystilbene-2-O-β-d-glucosides (TSG) on a mitochondrial dysfunction cell model induced by sodium azide and elucidate the underlying mechanisms.

Methods

Mitochondrial membrane potential (MMP) was detected by a fluorescence method. Cellular adenosine triphosphate (ATP) level was measured using a firefly luciferase-based kit. Reactive oxygen species (ROS) was detected using dichlorofluorescin diacetate (DCFH-DA). The expression levels of Bcl-2 and Bax were measured by Western blotting assay. Flow cytometry was utilized to measure apoptosis.

Results

Pretreatment of TSG (25–200 μmol/L) for 24 h significantly elevated MMP and ATP content, reduced ROS level and Bax/Bcl-2 ratio, and inhibited apoptosis in SH-SY5Y cells exposed to sodium azide.

Conclusion

These results suggest that TSG protects SH-SY5Y cells against sodium azide-induced mitochondrial dysfunction and apoptosis. These findings are helpful to understand the protective effect of TSG on mitochondria, which are involved in the early stage of AD.

A Highly Cellular Uptake Ternary Nanocomposite Titanate Nano-Tubes/CuFe₂O₄/Zn-Fe Could Induce Intrinsic Apoptosis of Prostate Cancer Cells: An Extended Study

Our previously prepared ternary nanocomposite TNT/CuFe₂O₄/Zn-Fe was highly engulfed by PC-3 cells, activated cytotoxicity that was dosage and time-subordinated, and demonstrated morphological alteration, which is one of the common characteristics of apoptotic cells. This prolonged study aimed to investigate other items. The study performed assays as Annexin V-FITC, flow cytometry, DNA ladder electrophoresis, and ROS assay for apoptosis detection, cell cycle analysis, DNA fragmentation, and ROS generation, respectively. In the PC-3-treated cells, the early and late phases of apoptosis with different percentages and DNA fragmentation were determined. Besides, the PC-3 cell cycle revealed the three major cell distribution different phases of the cycle (G1, S, and G2/M), and the Sub G1, which corresponded to apoptotic cells. The results proved the presence of ROS that triggered the intrinsic apoptotic pathway, which was confirmed through a decrease in (Bcl-2), the release of cytochrome c, activation of caspase-9, and caspase-3. To conclude, the ternary nanocomposite TNT/CuFe₂O₄/Zn-Fe achieved biochemical features alterations and could induce intrinsic apoptosis of PC-3 cells. The planned work of the current research will illuminate the arrested phase in the cell cycle through studying tumor suppressor genes such as p53 and Retinoblastoma RB, c-Myc oncogene, and cyclin-dependent kinases (Cdks) as well as their regulators.

Transcriptomic Profiling of In Vitro Tumor-Stromal Cell Paracrine Crosstalk Identifies Involvement of the Integrin Signaling Pathway in the Pathogenesis of Mesenteric Fibrosis in Human Small Intestinal Neuroendocrine Neoplasms

Aim

Analysis of the pathophysiology of mesenteric fibrosis (MF) in small intestinal neuroendocrine tumors (SI-NETs) in an in vitro paracrine model and in human SI-NET tissue samples.

Methods

An indirect co-culture model of SI-NET cells KRJ-I and P-STS with stromal cells HEK293 was designed to evaluate the paracrine effects on cell metabolic activity, gene expression by RT2 PCR Profilers to analyse cancer and fibrosis related genes, and RNA sequencing. The integrin signaling pathway, a specific Ingenuity enriched pathway, was further explored in a cohort of human SI-NET tissues by performing protein analysis and immunohistochemistry.

Results

RT Profiler array analysis demonstrated several genes to be significantly up- or down-regulated in a cell specific manner as a result of the paracrine effect. This was further confirmed by employing RNA sequencing revealing multiple signaling pathways involved in carcinogenesis and fibrogenesis that were significantly affected in these cell lines. A significant upregulation in the expression of various integrin pathway – related genes was identified in the mesenteric mass of fibrotic SI-NET as confirmed by RT-qPCR and immunohistochemistry. Protein analysis demonstrated downstream activation of the MAPK and mTOR pathways in some patients with fibrotic SI-NETs.

Conclusion

This study has provided the first comprehensive analysis of the crosstalk of SI-NET cells with stromal cells. A novel pathway – the integrin pathway – was identified and further validated and confirmed in a cohort of human SI-NET tissue featured by a dual role in fibrogenesis/carcinogenesis within the neoplastic fibrotic microenvironment.

Effects of variable oxygen regimes on mitochondrial bioenergetics and reactive oxygen species production in a marine bivalve, Mya arenaria

Estuarine and coastal benthic organisms often experience fluctuations in oxygen levels that can negatively impact their mitochondrial function and aerobic metabolism. To study these impacts, we exposed a common sediment-dwelling bivalve, the soft-shell clam Mya arenaria, for 21 days to chronic hypoxia (P _O2  ∼4.1 kPa), cyclic hypoxia (P _O2  ∼12.7-1.9 kPa, mean 5.7 kPa) or normoxia (P _O2  ∼21.1 kPa). pH was manipulated to mimic the covariation in CO₂/pH and oxygen levels in coastal hypoxic zones. Mitochondrial respiration, including proton leak, the capacity for oxidative phosphorylation (OXPHOS), the maximum activity of the electron transport system (ETS), reactive oxygen species (ROS) production, and activity and oxygen affinity of cytochrome c oxidase (CCO) were assessed. Acclimation to constant hypoxia did not affect the studied mitochondrial traits except for a modest decrease in the OXPHOS coupling efficiency. Cyclic hypoxia had no effect on OXPHOS or ETS capacity, but increased proton leak and lowered mitochondrial OXPHOS coupling efficiency. Furthermore, mitochondria of clams acclimated to cyclic hypoxia had higher rates of ROS generation compared with the clams acclimated to normoxia or chronic hypoxia. CCO activity was upregulated under cyclic hypoxia, but oxygen affinity of CCO did not change. These findings indicate that long-term cyclic hypoxia has a stronger impact on the mitochondria of M. arenaria than chronic hypoxia and might lead to impaired ATP synthesis, higher costs of mitochondrial maintenance and oxidative stress. These changes might negatively affect populations of M. arenaria in the coastal Baltic Sea under increasing hypoxia pressure.

Pregnancy swimming prevents early brain mitochondrial dysfunction and causes sex-related long-term neuroprotection following neonatal hypoxia-ischemia in rats

Neonatal hypoxia-ischemia (HI) is a major cause of cognitive impairments in infants. Antenatal strategies improving the intrauterine environment can have high impact decreasing pregnancy-derived intercurrences. Physical exercise alters the mother-fetus unity and has been shown to prevent the energetic challenge imposed by HI. This study aimed to reveal neuroprotective mechanisms afforded by pregnancy swimming on early metabolic failure and late cognitive damage, considering animals' sex as a variable. Pregnant Wistar rats were submitted to daily swimming exercise (20' in a tank filled with 32 °C water) during pregnancy. Neonatal HI was performed in male and female pups at postnatal day 7. Electron chain transport, mitochondrial mass and function and ROS formation were assessed in the right brain hemisphere 24 h after HI. From PND45, reference and working spatial memory were tested in the Morris water maze. MicroPET-FDG images were acquired 24 h after injury (PND8) and at PND60, following behavioral analysis. HI induced early energetic failure, decreased enzymatic activity in electron transport chain, increased production of ROS in cortex and hippocampus as well as caused brain glucose metabolism dysfunction and late cognitive impairments. Maternal swimming was able to prevent mitochondrial dysfunction and to improve spatial memory. The intergenerational effects of swimming were sex-specific, since male rats were benefited most. In conclusion, maternal swimming was able to affect the mitochondrial response to HI in the offspring's brains, preserving its function and preventing cognitive damage in a sex-dependent manner, adding relevant information on maternal exercise neuroprotection and highlighting the importance of mitochondria as a therapeutic target for HI neuropathology.

Effects of environmental cocaine concentrations on COX and caspase-3 activity, GRP-78, ALT, CRP and blood glucose levels in the liver and kidney of the European eel (Anguilla anguilla)

Cocaine is one of the most widely used illicit drugs in the world, and as a result of incomplete removal by sewage treatment plants it is found in surface waters, where it represents a new potential risk for aquatic organisms. In this study we evaluated the influence of environmental concentrations of cocaine on the liver and the kidney of the European eel (Anguilla anguilla). The eels were exposed to 20 ng L^-1 of cocaine for fifty days, after which, three and ten days after the interruption of cocaine exposure their livers and kidneys were compared to controls. The general morphology of the two organs was evaluated, as well as the following parameters: cytochrome oxidase (COX) and caspase-3 activities, as markers of oxidative metabolism and apoptosis activation, respectively; glucose-regulated protein (GRP)78 levels, as a marker of endoplasmic reticulum (ER)-stress; blood glucose level, as stress marker; serum levels of alanine aminotransferase (ALT), as a marker of liver injury and serum levels of C-reactive protein (CRP), as a marker of the inflammatory process. The liver showed morphologic alterations such as necrotic areas, karyolysis and pyknotic nuclei, while the kidneys had dilated glomeruli and the renal tubules showed pyknotic nuclei and karyolysis. In the kidney, the alterations persisted after the interruption of cocaine exposure. In the liver, COX and caspase-3 activities increased (COX: P = 0.01; caspase-3: P = 0.032); ten days after the interruption of cocaine exposure, COX activity returned to control levels (P = 0.06) whereas caspase-3 activity decreased further (P = 0.012); GRP78 expression increased only in post-exposure recovery specimens (three days: P = 0.007 and ten days: P = 0.008 after the interruption of cocaine exposure, respectively). In the kidney, COX and caspase-3 activities increased (COX: P = 0.02; caspase-3: P = 0.019); after the interruption of cocaine exposure, COX activity remained high (three days: P = 0.02 and ten days: P = 0.029 after the interruption of cocaine exposure, respectively) whereas caspase-3 activity returned to control values (three days: P = 0.69 and ten days: P = 0.67 after the interruption of cocaine exposure, respectively). Blood glucose and serum ALT and CRP levels increased (blood glucose: P = 0.01; ALT: P = 0.001; CRP: 0.015) and remained high also ten days after the interruption of cocaine exposure (blood glucose: P = 0.009; ALT: P = 0.0031; CRP: 0.036). These results suggest that environmental cocaine concentrations adversely affected liver and kidney of this species.

Serine-70 phosphorylated Bcl-2 prevents oxidative stress-induced DNA damage by modulating the mitochondrial redox metabolism

Bcl-2 phosphorylation at serine-70 (S70pBcl2) confers resistance against drug-induced apoptosis. Nevertheless, its specific mechanism in driving drug-resistance remains unclear. We present evidence that S70pBcl2 promotes cancer cell survival by acting as a redox sensor and modulator to prevent oxidative stress-induced DNA damage and execution. Increased S70pBcl2 levels are inversely correlated with DNA damage in chronic lymphocytic leukemia (CLL) and lymphoma patient-derived primary cells as well as in reactive oxygen species (ROS)- or chemotherapeutic drug-treated cell lines. Bioinformatic analyses suggest that S70pBcl2 is associated with lower median overall survival in lymphoma patients. Empirically, sustained expression of the redox-sensitive S70pBcl2 prevents oxidative stress-induced DNA damage and cell death by suppressing mitochondrial ROS production. Using cell lines and lymphoma primary cells, we further demonstrate that S70pBcl2 reduces the interaction of Bcl-2 with the mitochondrial complex-IV subunit-5A, thereby reducing mitochondrial complex-IV activity, respiration and ROS production. Notably, targeting S70pBcl2 with the phosphatase activator, FTY720, is accompanied by an enhanced drug-induced DNA damage and cell death in CLL primary cells. Collectively, we provide a novel facet of the anti-apoptotic Bcl-2 by demonstrating that its phosphorylation at serine-70 functions as a redox sensor to prevent drug-induced oxidative stress-mediated DNA damage and execution with potential therapeutic implications.

Light-induced modulation of the mitochondrial respiratory chain activity: possibilities and limitations

Biological effects of high fluence low-power (HFLP) lasers have been reported for some time, yet the molecular mechanisms procuring cellular responses remain obscure. A better understanding of the effects of HFLP lasers on living cells will be instrumental for the development of new experimental and therapeutic strategies. Therefore, we investigated sub-cellular mechanisms involved in the laser interaction with human hepatic cell lines. We show that mitochondria serve as sub-cellular "sensor" and "effector" of laser light non-specific interactions with cells. We demonstrated that despite blue and red laser irradiation results in similar apoptotic death, cellular signaling and kinetic of biochemical responses are distinct. Based on our data, we concluded that blue laser irradiation inhibited cytochrome c oxidase activity in electron transport chain of mitochondria. Contrary, red laser triggered cytochrome c oxidase excessive activation. Moreover, we showed that Bcl-2 protein inhibited laser-induced toxicity by stabilizing mitochondria membrane potential. Thus, cells that either overexpress or have elevated levels of Bcl-2 are protected from laser-induced cytotoxicity. Our findings reveal the mechanism how HFLP laser irradiation interfere with cell homeostasis and underscore that such laser irradiation permits remote control of mitochondrial function in the absence of chemical or biological agents.

Non-invasive treatment with near-infrared light: A novel mechanisms-based strategy that evokes sustained reduction in brain injury after stroke

Ischemic stroke is a debilitating disease that causes significant brain injury. While restoration of blood flow is critical to salvage the ischemic brain, reperfusion can exacerbate damage by inducing generation of reactive oxygen species (ROS). Recent studies by our group found that non-invasive mitochondrial modulation with near-infrared (NIR) light limits ROS generation following global brain ischemia. NIR interacts with cytochrome c oxidase (COX) to transiently reduce COX activity, attenuate mitochondrial membrane potential hyperpolarization, and thus reduce ROS production. We evaluated a specific combination of COX-inhibitory NIR (750 nm and 950 nm) in a rat stroke model with longitudinal analysis of brain injury using magnetic resonance imaging. Treatment with NIR for 2 h resulted in a 21% reduction in brain injury at 24 h of reperfusion measured by diffusion-weighted imaging (DWI) and a 25% reduction in infarct volume measured by T2-weighted imaging (T2WI) at 7 and 14 days of reperfusion, respectively. Additionally, extended treatment reduced brain injury in the acute phase of brain injury, and 7 and 14 days of reperfusion, demonstrating a >50% reduction in infarction. Our data suggest that mitochondrial modulation with NIR attenuates ischemia-reperfusion injury and evokes a sustained reduction in infarct volume following ischemic stroke.

Piscidin-1 Induces Apoptosis via Mitochondrial Reactive Oxygen Species-Regulated Mitochondrial Dysfunction in Human Osteosarcoma Cells

Osteosarcoma (OSA) is the most common type of cancer that originates in the bone and usually occurs in young children. OSA patients were treated with neoadjuvant chemotherapy and surgery, and the results were disappointing. Marine antimicrobial peptides (AMPs) have been the focus of antibiotic research because they are resistant to pathogen infection. Piscidin-1 is an AMP from the hybrid striped bass (Morone saxatilis × M. chrysops) and has approximately 22 amino acids. Research has shown that piscidin-1 can inhibit bacterial infections and has antinociception and anti-cancer properties; however, the regulatory effects of piscidin-1 on mitochondrial dysfunction in cancer cells are still unknown. We aimed to identify the effects of piscidin-1 on mitochondrial reactive oxygen species (mtROS) and apoptosis in OSA cells. Our analyses indicated that piscidin-1 has more cytotoxic effects against OSA cells than against lung and ovarian cancer cells; however, it has no effect on non-cancer cells. Piscidin-1 induces apoptosis in OSA cells, regulates mtROS, reduces mitochondrial antioxidant manganese superoxide dismutase and mitochondrial transmembrane potential, and decreases adenosine 5′-triphosphate production, thus leading to mitochondrial dysfunction and apoptosis. The mitochondrial antioxidant, mitoTempo, reduces the apoptosis induced by piscidin-1. Results suggest that piscidin-1 has potential for use in OSA treatment.

Cytochrome c Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity

Cytochrome c oxidase (COX) is regulated through tissue-, development- or environment-controlled expression of subunit isoforms. The COX4 subunit is thought to optimize respiratory chain function according to oxygen-controlled expression of its isoforms COX4i1 and COX4i2. However, biochemical mechanisms of regulation by the two variants are only partly understood. We created an HEK293-based knock-out cellular model devoid of both isoforms (COX4i1/2 KO). Subsequent knock-in of COX4i1 or COX4i2 generated cells with exclusive expression of respective isoform. Both isoforms complemented the respiratory defect of COX4i1/2 KO. The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and COX4i2-expressing cells. Also, COX activity, cytochrome c affinity, and respiratory rates were undistinguishable in cells expressing either isoform. Analysis of energy metabolism and the redox state in intact cells uncovered modestly increased preference for mitochondrial ATP production, consistent with the increased NADH pool oxidation and lower ROS in COX4i2-expressing cells in normoxia. Most remarkable changes were uncovered in COX oxygen kinetics. The p₅₀ (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme. Our finding supports the key role of the COX4i2-containing enzyme in hypoxia-sensing pathways of energy metabolism.

Mitochondrial Mechanisms Underlying Tolerance to Fluctuating Oxygen Conditions: Lessons from Hypoxia-Tolerant Organisms

Oxygen (O2) is essential for most metazoan life due to its central role in mitochondrial oxidative phosphorylation (OXPHOS), which generates >90% of the cellular adenosine triphosphate. O2 fluctuations are an ultimate mitochondrial stressor resulting in mitochondrial damage, energy deficiency, and cell death. This work provides an overview of the known and putative mechanisms involved in mitochondrial tolerance to fluctuating O2 conditions in hypoxia-tolerant organisms including aquatic and terrestrial vertebrates and invertebrates. Mechanisms of regulation of the mitochondrial OXPHOS and electron transport system (ETS) (including alternative oxidases), sulphide tolerance, regulation of redox status and mitochondrial quality control, and the potential role of hypoxia-inducible factor (HIF) in mitochondrial tolerance to hypoxia are discussed. Mitochondrial phenotypes of distantly related animal species reveal common features including conservation and/or anticipatory upregulation of ETS capacity, suppression of reactive oxygen species (ROS)-producing electron flux through ubiquinone, reversible suppression of OXPHOS activity, and investment into the mitochondrial quality control mechanisms. Despite the putative importance of oxidative stress in adaptations to hypoxia, establishing the link between hypoxia tolerance and mitochondrial redox mechanisms is complicated by the difficulties of establishing the species-specific concentration thresholds above which the damaging effects of ROS outweigh their potentially adaptive signaling function. The key gaps in our knowledge about the potential mechanisms of mitochondrial tolerance to hypoxia include regulation of mitochondrial biogenesis and fusion/fission dynamics, and HIF-dependent metabolic regulation that require further investigation in hypoxia-tolerant species. Future physiological, molecular and genetic studies of mitochondrial responses to hypoxia, and reoxygenation in phylogenetically diverse hypoxia-tolerant species could reveal novel solutions to the ubiquitous and metabolically severe problem of O2 deficiency and would have important implications for understanding the evolution of hypoxia tolerance and the potential mitigation of pathological states caused by O2 fluctuations.

Influence of Structured Water Layers on Protein Adsorption Process: A Case Study of Cytochrome c and Carbon Nanotube Interactions and Its Implications

Cytochrome c, an essential protein of the electron transport chain, is known to be capable of amplifying the toxicity of carbon nanomaterials via free-radical generation. To understand their interaction, as well as the more general protein-nanoparticle interaction at molecular levels, we investigate the adsorptions between cytochrome c and carbon nanotubes (CNTs) in dynamic and thermodynamic ways using molecular dynamics simulations. The results reveal a well-defined three-phase process separated by two transition points: the diffusion phase where the protein diffuses in the water box, the lockdown phase I where the protein inserts into the surface-bound water layers and rearranges its conformation to fit to the surface of the CNT, and the lockdown phase II where cytochrome c repels the water molecules standing in its way to the surface of CNT and reaches stable adsorption states. The structured water layers affect the movement of atoms by electrostatic forces. In lockdown phase I, the conformation adjustment of the protein dominates the adsorption process. The most thermally favorable adsorption conformation is determined. It shows that except for the deformation of short β sheets and some portions of α helixes, most of the secondary structures of cytochrome c remain unchanged, implying that most of the functions of cytochrome c are preserved. During these processes, the energy contributions of the hydrophilic residues of cytochrome c are much larger than those of hydrophobic residues. Interestingly, the structured water layers at the CNT surface allow more hydrophilic residues such as Lys to get into close contact with the CNT, which plays a significant role during the anchoring process of adsorption. Our results demonstrate that the heme group is in close contact with the CNT in some of the adsorbed states, which hence provides a way for electron transfer from cytochrome c to the CNT surface.

The bimodal mechanism of interaction between dopamine and mitochondria as reflected in Parkinson's disease and in schizophrenia

Parkinson's disease (PD) and schizophrenia (SZ) are two CNS disorders in which dysfunctions in the dopaminergic system and mitochondria are major pathologies. The symptomology of both, PD a neurodegenerative disorder and SZ a neurodevelopmental disorder, is completely different. However, the pharmacological treatment of each of the diseases can cause a shift of symptoms into those characteristic of the other disease. In this review, I describe a pathological interaction between dopamine and mitochondria in both disorders, which due to differences in the extent of oxidative stress leads either to cell death and tissue degeneration as in PD substantia nigra pars compacta or to distorted neuronal activity, imbalanced neuronal circuitry and abnormal behavior and cognition in SZ. This review is in the honor of Moussa Youdim who introduced me to the secrets of research work. His enthusiasm, curiosity and novelty-seeking inspired me throughout my career. Thank you Moussa.

Postconditioning Protection Against Myocardiocyte Anoxia/Reoxygenation Injury From Penehyclidine Hydrochloride

BACKGROUND/AIMS

To investigate the postconditioning protective effect of penehyclidine hydrochloride (PHC) against anoxia/reoxygenation (A/R) injury in H9c2 cells along with the involved mechanism and timing effect.

METHODS

We divided H9c2 cells into 7 groups: control group, A/R group and PHC+A/R groups at 0 min, 5 mins, 10 mins, 20 mins, 30 mins, respectively (treated with 0.1 μm/L PHC at 0 min, 5 mins, 10 mins, 20 mins, 30 mins after the reoxygenation procedure began). Cell apoptosis, oxidative stress, intracellular Ca2+ concentration, mitochondrial membrane potential and mitochondrial permeability transition pore (MPTP) opening were explored. Bcl-2, Bax, Cyt C, caspase-3 and caspase-9 levels were measured.

RESULTS

A/R significantly increased both cell injury and cell apoptosis. PHC showed postconditioning protective effect by attenuating superoxide production, decreasing Ca2+ overload, restraining MPTP activities, restoring mitochondrial membrane potential, regulating cell apoptosis proteins and modulation of mitochondrial pathway. Earlier administration of PHC offered greater postconditioning protective effect.

CONCLUSION

H9c2 cells were protected by PHC from A/R injury regardless of timing of PHC administration (0 min, 5 mins, 10 mins, 20 mins, 30 mins). However, earlier administration of PHC resulted in better PHC postconditioning protection.

Cell stress management by the mitochondrial LonP1 protease - Insights into mitigating developmental, oncogenic and cardiac stress

Mitochondrial LonP1 is an essential stress response protease that mediates mitochondrial proteostasis, metabolism and bioenergetics. Homozygous and compound heterozygous variants in the LONP1 gene encoding the LonP1 protease have recently been shown to cause a diverse spectrum of human pathologies, ranging from classical mitochondrial disease phenotypes, profound neurologic impairment and multi-organ dysfunctions, some of which are uncommon to mitochondrial disorders. In this review, we focus primarily on human LonP1 and discuss findings, which demonstrate its multidimensional roles in maintaining mitochondrial proteostasis and adapting cells to metabolic flux and stress during normal physiology and disease processes. We also discuss emerging roles of LonP1 in responding to developmental, oncogenic and cardiac stress.

The Protective Effects of Thymosin-β-4 in a Rat Model of Ischemic Acute Kidney Injury

BACKGROUND

Despite the progress in the treatment of acute kidney injury (AKI), current curative approaches fail to provide adequate treatment. In this study, we aimed to investigate the possible protective effects of thymosin-β-4(Tβ4) on an ischemic AKI model in rats.

METHODS

Rats were randomly assigned into four groups (n = 8/group): The control group (sham-operated), the ischemia-reperfusion (I/R) group; renal ischemia (90 min) by infrarenal abdominal aortic occlusion followed by reperfusion (3 h), the Tβ4 + I/R group; treated with Tβ4 before I/R, and the I/Tβ4/R group; treated with Tβ4 just before reperfusion. Besides renal function determination (creatinine (Cr) and blood urea nitrogen (BUN)); histological evaluation was also conducted. Renal tissue caspase-9, matrix metalloproteinase (MMP-9) activities, and hyaluronan levels were measured. Additionally, renal tissue oxidative stress (lipid hydroperoxide, malondialdehyde, superoxide dismutase, glutathione, pro-oxidant-antioxidant balance, ferric reducing antioxidant power, nitric oxide), inflammation (tumor necrosis factor-α, interleukin-1β, interleukin-6, nuclear factor-κβ) were evaluated.

RESULTS

I/R increased the level of caspase-9, MMP-9 activity, and hyaluronan (p < 0.001) and these were significantly decreased in both Tβ4 groups. Moreover, I/R led to increases in oxidative stress and inflammation parameters (p < 0.001) while the levels of antioxidants were decreased. Nevertheless, Tβ4 in both groups were able to restore oxidative stress and inflammation parameters. Furthermore, Tβ4 attenuated histologic injury caused by I/R (p < 0.01) and diminished serum urea-creatinine levels (p < 0.001).

CONCLUSION

These results suggest that Tβ4 has significant improving effects in ischemic acute kidney injury. This beneficial effect might be a result of the inhibition of extracellular matrix remodeling and apoptosis cascade via modulation in renal redox status and inflammation.

Uncoupling protein 1 inhibits mitochondrial reactive oxygen species generation and alleviates acute kidney injury

BACKGROUND

Uncoupling protein 1 (UCP1) is predominantly found in brown adipose tissue mitochondria, and mediates energy dissipation to generate heat rather than ATP via functional mitochondrial uncoupling. However, little is known about its expression and function in kidney.

METHODS

We carried out a mRNA microarray analysis in mice kidneys with ischemia reperfusion (IR) injury. The most dramatically downregulated gene UCP1 after IR was identified, and its role in generation of mitochondrial reactive oxygen species (ROS) and oxidative stress injury was assessed both in vitro and in vivo. Genetic deletion of UCP1 was used to investigate the effects of UCP1 on ischemia or cisplatin-indued acute kidney injury (AKI) in mice.

FINDINGS

UCP1 was located in renal tubular epithelial cells in kidney and downregulated in a time-dependent manner during renal IR. Deletion of UCP1 increased oxidative stress in kidneys and aggravated ischemia or cisplatin induced AKI in mice.Viral-based overexpression of UCP1 reduced mitochondrial ROS generation and apoptosis in hypoxia-treated tubular epithelial cells. Furthermore, UCP1 expression was regulated by peroxisome proliferator-activator receptor (PPAR) γ in kidneys during renal IR. Overexpression of PPAR-γ resembled UCP1-overexpression phenotype in vitro. Treatment with PPAR-γ agonist could induce UCP1 upregulation and provide protective effect against renal IR injury in UCP1^+/+mice, but not in UCP1^-/-mice.

INTERPRETATION

UCP1 protects against AKI likely by suppressing oxidative stress, and activation of UCP1 represents a potential therapeutic strategy for AKI. FUND: National Natural Science Foundation of China grants, Science and Technology Commission of Shanghai.

TRAF1 Exacerbates Myocardial Ischemia Reperfusion Injury via ASK1-JNK/p38 Signaling

Background After acute myocardial infarction, the recovery of ischemic myocardial blood flow may cause myocardial reperfusion injury, which reduces the efficacy of myocardial reperfusion. Ways to reduce and prevent myocardial ischemia/reperfusion (I/R) injury are of great clinical significance in the treatment of patients with acute myocardial infarction. TRAF1 (tumor necrosis factor receptor-associated factor 1) is an important adapter protein that is implicated in molecular events regulating immunity, inflammation, and cell death. Little is known about the role and impact of TRAF1 in myocardial I/R injury. Methods and Results TRAF1 expression is markedly induced in wild-type mice and cardiomyocytes after I/R or hypoxia/reoxygenation stimulation. I/R models were established in TRAF1 knockout mice and wild type mice (n=10 per group). We demonstrated that TRAF1 deficiency protects against myocardial I/R-induced loss of heat function, inflammation, and cardiomyocyte death. In addition, overexpression of TRAF1 in primary cardiomyocytes promotes hypoxia/reoxygenation-induced inflammation and apoptosis in vitro. Mechanistically, TRAF1 promotes myocardial I/R injury through regulating ASK1 (apoptosis signal-regulating kinase 1)-mediated JNK/p38 (c-Jun N-terminal kinase/p38) MAPK (mitogen-activated protein kinase) cascades. Conclusions Our results indicated that TRAF1 aggravates the development of myocardial I/R injury by enhancing the activation of ASK1-mediated JNK/p38 cascades. Targeting the TRAF1-ASK1-JNK/p38 pathway provide feasible therapies for cardiac I/R injury.

Quantification of the severity of hypoxic-ischemic brain injury in a neonatal preclinical model using measurements of cytochrome-c-oxidase from a miniature broadband-near-infrared spectroscopy system

We describe the development of a miniaturized broadband near-infrared spectroscopy system (bNIRS), which measures changes in cerebral tissue oxyhemoglobin ( [ HbO 2 ] ) and deoxyhemoglobin ([HHb]) plus tissue metabolism via changes in the oxidation state of cytochrome-c-oxidase ([oxCCO]). The system is based on a small light source and a customized mini-spectrometer. We assessed the instrument in a preclinical study in 27 newborn piglets undergoing transient cerebral hypoxia-ischemia (HI). We aimed to quantify the recovery of the HI insult and estimate the severity of the injury. The recovery in brain oxygenation ( Δ [ HbDiff ] = Δ [ HbO 2 ] - Δ [ HHb ] ), blood volume ( Δ [ HbT ] = Δ [ HbO 2 ] + Δ [ HHb ] ), and metabolism ( Δ [ oxCCO ] ) for up to 30 min after the end of HI were quantified in percentages using the recovery fraction (RF) algorithm, which quantifies the recovery of a signal with respect to baseline. The receiver operating characteristic analysis was performed on bNIRS-RF measurements compared to proton ( H 1 ) magnetic resonance spectroscopic (MRS)-derived thalamic lactate/N-acetylaspartate (Lac/NAA) measured at 24-h post HI insult; Lac/NAA peak area ratio is an accurate surrogate marker of neurodevelopmental outcome in babies with neonatal HI encephalopathy. The Δ [ oxCCO ] -RF cut-off threshold of 79% within 30 min of HI predicted injury severity based on Lac/NAA with high sensitivity (100%) and specificity (93%). A significant difference in thalamic Lac/NAA was noticed ( p < 0.0001 ) between the two groups based on this cut-off threshold of 79% Δ [ oxCCO ] -RF. The severe injury group ( n = 13 ) had ∼ 30 % smaller recovery in Δ [ HbDiff ] -RF ( p = 0.0001 ) and no significant difference was observed in Δ [ HbT ] -RF between groups. At 48 h post HI, significantly higher P 31 -MRS-measured inorganic phosphate/exchangeable phosphate pool (epp) ( p = 0.01 ) and reduced phosphocreatine/epp ( p = 0.003 ) were observed in the severe injury group indicating persistent cerebral energy depletion. Based on these results, the bNIRS measurement of the oxCCO recovery fraction offers a noninvasive real-time biomarker of brain injury severity within 30 min following HI insult.

Phosphorylation of OXPHOS Machinery Subunits: Functional Implications in Cell Biology and Disease

The complexes of the electron transport chain and ATP synthase comprise the oxidative phosphorylation (OXPHOS) system. The reactions of OXPHOS generate the mitochondrial membrane potential, drive the majority of ATP production in respiring cells, and contribute significantly to cellular reactive oxygen species (ROS). Regulation of OXPHOS is therefore critical to maintain cellular homeostasis. OXPHOS machinery subunits have been found to be highly phosphorylated, implicating this post-translational modification as a means whereby OXPHOS is regulated. Multiple lines of evidence now reveal the diverse mechanisms by which phosphorylation of OXPHOS machinery serve to regulate individual complex stability and activity as well as broader cellular functions. From these mechanistic studies of OXPHOS machinery phosphorylation, it is now clear that many aspects of human health and disease are potentially impacted by phosphorylation of OXPHOS complexes. This mini-review summarizes recent studies that provide robust mechanistic detail related to OXPHOS subunit phosphorylation.

Immunological implications of epidermal growth factor receptor signaling in persistent infections

Infectious diseases account for a large proportion of global health emergencies and are rising more so owing to the paucity of effective vaccination and chemotherapeutic strategies. The severity is compounded by the development of antibiotic resistance among major pathogenic strains, capable of residing in the hostile host microenvironment by hijacking its signaling mechanisms and molecular circuitry. Among such processes, studies on epidermal growth factor receptor (EGFR) have revealed specific contributions of this classical oncogenic signaling axis during distinct infection conditions. Here, we review the current status of EGFR family members in the context of host-pathogen interactions and speculate the possible dimensions of exploration and manipulation of the EGFR pathway for host-directed therapeutic purposes.

Proteomic Analysis of Rat Cerebral Cortex in the Subacute to Long-Term Phases of Focal Cerebral Ischemia-Reperfusion Injury

Stroke is a leading cause of mortality and disability, and ischemic stroke accounts for more than 80% of the disease occurrence. Timely reperfusion is essential in the treatment of ischemic stroke, but it is known to cause ischemia-reperfusion (I/R) injury and the relevant studies have mostly focused on the acute phase. Here we reported on a global proteomic analysis to investigate the development of cerebral I/R injury in the subacute and long-term phases. A rat model was used, with 2 h-middle cerebral artery occlusion (MCAO) followed with 1, 7, and 14 days of reperfusion. The proteins of cerebral cortex were analyzed by SDS-PAGE, whole-gel slicing, and quantitative LC-MS/MS. Totally 5621 proteins were identified, among which 568, 755, and 492 proteins were detected to have significant dys-regulation in the model groups with 1, 7, and 14 days of reperfusion, respectively, when compared with the corresponding sham groups (n = 4, fold change ≥1.5 or ≤0.67 and p ≤ 0.05). Bioinformatic analysis on the functions and reperfusion time-dependent dys-regulation profiles of the proteins exhibited changes of structures and biological processes in cytoskeleton, synaptic plasticity, energy metabolism, inflammation, and lysosome from subacute to long-term phases of cerebral I/R injury. Disruption of cytoskeleton and synaptic structures, impairment of energy metabolism processes, and acute inflammation responses were the most significant features in the subacute phase. With the elongation of reperfusion time to the long-term phase, a tendency of recovery was detected on cytoskeleton, while inflammation pathways different from the subacute phase were activated. Also, lysosomal structures and functions might be restored. This is the first work reporting the proteome changes that occurred at different time points from the subacute to long-term phases of cerebral I/R injury and we expect it would provide useful information to improve the understanding of the mechanisms involved in the development of cerebral I/R injury and suggest candidates for treatment.

Mitochondrial Dysfunctions: A Thread Sewing Together Alzheimer's Disease, Diabetes, and Obesity

Metabolic disorders are severe and chronic impairments of the health of many people and represent a challenge for the society as a whole that has to deal with an ever-increasing number of affected individuals. Among common metabolic disorders are Alzheimer's disease, obesity, and type 2 diabetes. These disorders do not have a univocal genetic cause but rather can result from the interaction of multiple genes, lifestyle, and environmental factors. Mitochondrial alterations have emerged as a feature common to all these disorders, underlining perhaps an impaired coordination between cellular needs and mitochondrial responses that could contribute to their development and/or progression.

The S1P mimetic fingolimod phosphate regulates mitochondrial oxidative stress in neuronal cells

Fingolimod is one of the few oral drugs available for the treatment of multiple sclerosis (MS), a chronic, inflammatory, demyelinating and neurodegenerative disease. The mechanism of action proposed for this drug is based in the phosphorylation of the molecule to produce its active metabolite fingolimod phosphate (FP) which, in turns, through its interaction with S1P receptors, triggers the functional sequestration of T lymphocytes in lymphoid nodes. On the other hand, part if not most of the damage produced in MS and other neurological disorders seem to be mediated by reactive oxygen species (ROS), and mitochondria is one of the main sources of ROS. In the present work, we have evaluated the anti-oxidant profile of FP in a model of mitochondrial oxidative damage induced by menadione (Vitk3) on neuronal cultures. We provide evidence that incubation of neuronal cells with FP alleviates the Vitk3-induced toxicity, due to a decrease in mitochondrial ROS production. It also decreases regulated cell death triggered by imbalance in oxidative stress (restore values of advanced oxidation protein products and total thiol levels). Also restores mitochondrial function (cytochrome c oxidase activity, mitochondrial membrane potential and oxygen consumption rate) and morphology. Furthermore, increases the expression and activity of protective factors (increases Nrf2, HO1 and Trx2 expression and GST and NQO1 activity), being some of these effects modulated by its interaction with the S1P receptor. FP seems to increase mitochondrial stability and restore mitochondrial dynamics under conditions of oxidative stress, making this drug a potential candidate for the treatment of neurodegenerative diseases other than MS.

Paeonol alleviates CCl4-induced liver fibrosis through suppression of hepatic stellate cells activation via inhibiting the TGF-β/Smad3 signaling

Objective: Paeonol is a natural phenolic component isolated from the root bark of peony with multiple pharmacological activities. We investigated the anti-fibrotic effect and underlying mechanism of paeonol. Methods: Twenty-four male C57BL/6J mice were divided into 4 groups (n = 6 in each group), injected with CCl₄ to induce liver fibrosis and administrated with paeonol according to the regimen. The serum activity of ALT and AST, and H&E staining were to assess liver injury. Sirius and Masson staining, and hydroxyproline content were to evaluate the degree of liver fibrosis. TNF-α, IL-6, TGF-β, MDA, GSH-PX, SOD, and CAT were detected to reflect inflammation and oxidative stress. RT-qPCR and Western blot analysis to assess the activation of HSCs and TGF-β/Smad3 signaling. Results: Paeonol ameliorated liver injury and liver fibrosis, reflected by the decrease of ALT, AST, less lesion in H&E staining, mitigated fibrosis in Sirius and Masson staining, lessened content of hydroxyproline. Paeonol attenuated the level of IL-6 and TNF-α, and elevated the activity of GSH-PX, SOD, and CAT with reducing the level of MDA. The expression of col 1a, α-SMA, vimentin, and desmin were down-regulated and TGF-β/Smad3 signaling pathway was inhibited. Conclusion: These data demonstrated that paeonol could alleviate CCl₄-induced liver fibrosis through suppression of hepatic stellate cells activation via inhibiting the TGF-β/Smad3 signaling.

Regulation of mitochondrial function as a promising target in platelet activation-related diseases

Platelets are anucleated cell elements produced by fragmentation of the cytoplasm of megakaryocytes and have a unique metabolic phenotype compared with circulating leukocytes, exhibiting a high coupling efficiency to mitochondrial adenosine triphosphate production with reduced respiratory reserve capacity. Platelet mitochondria are well suited for ex vivo analysis of different diseases. Even some diseases induce mitochondrial changes in platelets without reflecting them in other organs. During platelet activation, an integrated participation of glycolysis and oxidative phosphorylation is mediated by oxidative stress production-dependent signaling. The platelet activation-dependent procoagulant activity mediated by collagen, thrombin and hyperglycemia induce mitochondrial dysfunction to promote thrombosis in oxidative stress-associated pathological conditions. Interestingly, some compounds exhibit a protective action on platelet mitochondrial dysfunction through control of mitochondrial oxidative stress production or inhibition of respiratory complexes. They can be grouped in a) Natural source-derived compounds (e.g. Xanthohumol, Salvianoloc acid A and Sila-amide derivatives of NAC), b) TPP⁺-linked small molecules (e.g. mitoTEMPO and mitoQuinone) and c) FDA-approved drugs (e.g. metformin and statins), illustrating the wide range of molecular structures capable of effectively interacting with platelet mitochondria. The present review article aims to discuss the mechanisms of mitochondrial dysfunction and their association with platelet activation-related diseases.

BA6 Induces Apoptosis via Stimulation of Reactive Oxygen Species and Inhibition of Oxidative Phosphorylation in Human Lung Cancer Cells

Lung cancer is the leading cause of cancer deaths in the world, with a five-year survival rate of less than 30%. Clinically effective chemotherapeutic treatments at the initial stage may eventually face the dilemma of no drug being effective due to drug resistance; therefore, finding new effective drugs for lung cancer treatment is a necessary and important issue. Compounds capable of further increasing the oxidative stress of cancer cells are considered to have anticancer potential because they possessed the ability to induce apoptosis. This study mainly investigated the effects of BA6 (heteronemin), the marine sponge sesterterpene, on lung cancer cell apoptosis, via modulation of mitochondrial reactive oxygen species (mtROS) and oxidative phosphorylation (OXPHOS). BA6 has cellular cytotoxic activities against a variety of cancer cell lines, but it has no effect on nontumor cells. The BA6-treated lung cancer cells show a significant increase in both cellular ROS and mtROS, which in turn caused the loss of mitochondrial membrane potential (MMP). The increase of oxidative stress in lung cancer cells treated with BA6 was accompanied by a decrease in the expression of antioxidant enzymes Cu/Zn SOD, MnSOD, and catalase. In addition, OXPHOS performed in the mitochondria and glycolysis in the cytoplasm were inhibited, which subsequently reduced downstream ATP production. Pretreatment with mitochondria-targeted antioxidant MitoTEMPO reduced BA6-induced apoptosis through the mitochondria-dependent apoptotic pathway, which was accompanied by increased cell viability, decreased mtROS, enhanced MMP, and suppressed expression of cleaved caspase-3 and caspase-9 proteins. In conclusion, the results of this study clarify the mechanism of BA6-induced apoptosis in lung cancer cells via the mitochondrial apoptotic pathway, suggesting that it is a potentially innovative alternative to the treatment of human lung cancer.

Proteome analysis of human mesenchymal stem cells undergoing chondrogenesis when exposed to the products of various magnesium-based materials degradation

Treatment of physeal fractures (15%–30% of all paediatric fractures) remains a challenge as in approximately 10% of the cases, significant growth disturbance may occur. Bioresorbable Magnesium-based implants represent a strategy to minimize damage (i.e., load support until bone healing without second surgery). Nevertheless, the absence of harmful effects of magnesium-implants and their degradation products on the growth plate should be confirmed. Here, the proteome of human mesenchymal stem cells undergoing chondrogenesis was evaluated when exposed to the products of various Magnesium-based materials degradation. The results of this study indicate that the materials induced regulation of proteins associated with cell chondrogenesis and cartilage formation, which should be beneficial for cartilage regeneration.

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Degradation products from Mg-based materials generated changes in protein expression.

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Relevant proteins involved in cartilage formation were upregulated.

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Potential application of especially Pure-Mg and Mg-10Gd for cartilage regeneration.

Protective properties of the cultured stem cell proteome studied in an animal model of acetaminophen-induced acute liver failure

Chronic overuse of common pharmaceuticals, e.g. acetaminophen (paracetamol), often leads to the development of acute liver failure (ALF). This study aimed to elucidate the effect of cultured mesenchymal stem cells (MSCs) proteome on the onset of liver damage and regeneration dynamics in animals with ALF induced by acetaminophen, to test the liver protective efficacy of MSCs proteome depending on the oxygen tension in cell culture, and to blueprint protein components responsible for the effect. Protein compositions prepared from MSCs cultured in mild hypoxic (5% and 10% O₂₎ and normal (21% O₂) conditions were used to treat ALF induced in mice by injection of acetaminophen. To test the effect of reduced oxygen tension in cell culture on resulting MSCs proteome content we applied a combination of high performance liquid chromatography and mass-spectrometry (LC-MS/MS) for the identification of proteins in lysates of MSCs cultured at different O₂ levels. The treatment of acetaminophen-administered animals with proteins released from cultured MSCs resulted in the inhibition of inflammatory reactions in damaged liver; the area of hepatocyte necrosis being reduced in the first 24 h. Compositions obtained from MSCs cultured at lower O₂ level were shown to be more potent than a composition prepared from normoxic cells. A comparative characterization of protein pattern and identification of individual components done by a cytokine assay and proteomics analysis of protein compositions revealed that even moderate hypoxia produces discrete changes in the expression of various subsets of proteins responsible for intracellular respiration and cell signaling. The application of proteins prepared from MSCs grown in vitro at reduced oxygen tension significantly accelerates healing process in damaged liver tissue. The proteomics data obtained for different preparations offer new information about the potential candidates in the MSCs protein repertoire sensitive to oxygen tension in culture medium, which can be involved in the generalized mechanisms the cells use to respond to acute liver failure.

Erianin protects against high glucose-induced oxidative injury in renal tubular epithelial cells

Erianin is the major bibenzyl compound found in Dendrobium chrysotoxum Lindl. The current study was designed to investigate the protective effects of erianin on high glucose-induced injury in cultured renal tubular epithelial cells (NRK-52E cells) and determine the possible mechanisms for its effects. NRK-52E cells were pretreated with erianin (5, 10, 25 or 50 nmol/L) for 1 h followed by further exposure to high glucose (30 mmol/L, HG) for 48 h. Erianin concentration dependently enhanced cell viability followed by HG treatment in NRK-52E cells. HG induced reactive oxygen species (ROS) generation, malondialdehyde production, and glutathione deficiency were recovered in NRK-52E cells pretreated with erianin. HG triggered cell apoptosis via the loss of mitochondrial membrane potential, depletion of adenosine triphosphate, upregulation of caspases 9 and 3, enhancement of cytochrome c release, and subsequent interruption of the Bax/Bcl-2 balance. These detrimental effects were ameliorated by erianin. HG also induced activation of p53, JNK, p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) in NRK-52E cells, which were blocked by erianin. The results suggest that treatment NRK-52E cells with erianin halts HG-induced renal dysfunction through the suppression of the ROS/MAPK/NF-κB signaling pathways. Our findings provide novel therapeutic targets for diabetic nephropathy.

Re-analysis of the coral Acropora digitifera transcriptome reveals a complex lncRNAs-mRNAs interaction network implicated in Symbiodinium infection

BACKGROUND

Being critically important to the ecosystem, the stability of coral reefs is directly related to the marine and surrounding terrestrial environments. However, coral reefs are now undergoing massive and accelerating devastation due to bleaching. The fact that the breakdown of symbiosis between coral and the dinoflagellate, zooxanthellae, has been well elucidated as the main cause of bleaching, implying the establishment of symbiosis with zooxanthellae plays a crucial role in maintaining coral survival. However, the relevant molecular and cellular mechanisms have not been well studied yet. In this study, based on the deep RNA-sequencing data derived from Mohamed, A. R. et al., an integrated transcriptome analysis was performed to deeply investigate global transcriptome changes of the coral Acropora digitifera in response to infection by dinoflagellate of the genus Symbiodinium.

RESULTS

The results revealed that compared to RefTranscriptome_v1.0 (A. digitifera transcriptome assembly v1.0), numerous novel transcripts and isoforms were identified, the Symbiodinium-infected coral larvae at 4 h generated the highest proportion of specific isoforms. Alternative splicing analysis showed that intron retention predominated in all alternative transcripts among six statuses. Additionally, 8117 lncRNAs were predicted via a stringent stepwise filtering pipeline. A complex lncRNAs-mRNAs network including 815 lncRNAs and 6395 mRNAs were established, in which 21 lncRNAs were differentially expressed at 4 h post infection. Functional clustering analysis for those differentially lncRNAs-coexpressed mRNAs demonstrated that several biological processes and pathways related to protein kinase activity, metabolic pathways, mitochondrion, ribosome, etc. were enriched.

CONCLUSIONS

Our study not only refined A. digitifera transcriptome via identification of novel transcripts and isoforms, but also predicted a high-confidence dataset of lncRNAs. Functional study based on the construction of lncRNAs-mRNAs co-expression network has disclosed a complex lncRNA-mediated regulation in response to Symbiodinium infection exhibited in A. digitifera. Once validated, these lncRNAs could be good potential targets for treatment and prevention of bleaching in coral.

Mitochondrial active and relaxed state respiration after heat shock mRNA response in the heart

Induction of Heat Shock Proteins results in cytoprotection. Beneficial effect results from transcription and translational cellular components' involvement that defends metabolism and thus induce ischemic protection of the tissue. Mitochondrial respiration is also involved in stress- induced conditions. It is not a uniform process. Cytochrome c Oxidase (CytOx) representing complex IV of the Electron Transfer Chain (ETC) has a regulatory role for mitochondrial respiratory activity, which is tested in our study after hsp induction. Moreover, protein translation for mitochondrial components was probed by the detection of MT-CO1 for Subunit 1 of CytOx neosynthesis. Wistar rats were subjected to whole-body hyperthermia at 42.0-42.5 °C for 15 min followed by a normothermic recovery period. Heat shock response was monitored time dependent from LV biopsies of all control and heat treated animals with PCR-analysis for hsp 32, 60, 70.1, 70.2, 90 and MT-CO1 expression at 15, 30, 45, 60, 120 and 360 min recovery (n = 5 in each group), respectively. Enzymatic activity of CytOx were evaluated polarographically. High energy phosphates were detected by chromatographic analysis. The mRNA expression of MT-CO1 peaked at 60 min and was accompanied by hsp 32 (r = 0.457; p = 0.037) and hsp 70.2 (r = 0.615; p = 0.003) upregulation. With hsp induction, mitochondrial respiration was increased initially. Enzymatic activity reconciled from active into relaxed status wherein CytOx activity was completely inhibited by ATP. Myocardial ATP content increased from stress induced point i.e. < 1 µmol g^-1 protein w/w to finally 1.5 ± 0.53 µmol g^-1 protein w/w at 120 min recovery interval. Hyperthermic, myocardial hsp- induction goes along with increased CytOx activity representing an increased "active" mitochondrial respiration. In parallel, de -novo holoenzyme assembly of CytOx begins as shown by MT-CO1 upregulation at 60 min recovery time crossing with a final return to the physiological "relaxed" state and ATP -inhibited respiration.

Mitochondrial Dysfunction Is Inducible in Lymphoblastoid Cell Lines From Children With Autism and May Involve the TORC1 Pathway

We previously developed a lymphoblastoid cell line (LCL) model of mitochondrial dysfunction in autism spectrum disorder (ASD); some individuals with ASD showed mitochondrial dysfunction (AD-A) while other individuals (AD-N) demonstrated mitochondrial respiration similar to controls (CNT). To test the hypothesis that mitochondrial dysfunction could be a consequence of environmental exposures through chronic elevations in reactive oxygen species (ROS), we exposed LCLs to prolonged ROS. We also examined expression of metabolic regulatory genes and the modulating effect of the mechanistic target of rapamycin (mTOR) pathway. Prolonged ROS exposure induced or worsened mitochondrial dysfunction in all LCL groups. Expression of genes associated with ROS protection was elevated in both AD-N and AD-A LCLs, but mitochondrial fission/fusion and mitoplasticity gene expression was only increased in AD-N LCLs. Partial least squares discriminant analysis showed that mTOR, UCP2 (uncoupling protein 2), SIRT1 (sirtuin 1), and MFN2 (mitofusin-2) gene expression differentiated LCL groups. Low-dose rapamycin (0.1 nM) normalized respiration with the magnitude of this normalization greater for AD-A LCLs, suggesting that the mammalian target of rapamycin complex 1 (mTORC1) pathway may have a different dynamic range for regulating mitochondrial activity in individuals with ASD with and without mitochondrial dysfunction, potentially related to S6K1 (S6 kinase beta-1) regulation. Understanding pathways that underlie mitochondrial dysfunction in ASD may lead to novel treatments.

Gigantol has Protective Effects against High Glucose-Evoked Nephrotoxicity in Mouse Glomerulus Mesangial Cells by Suppressing ROS/MAPK/NF-κB Signaling Pathways

Gigantol is a bibenzyl compound derived from several medicinal orchids. This biologically active compound has shown promising therapeutic potential against diabetic cataracts, but whether this compound exerts beneficial effects on the other diabetic microvascular complications remains unclear. This study was carried out to examine effects of gigantol on high glucose-induced renal cell injury in cultured mouse kidney mesangial cells (MES-13). MES-13 cells were pretreated with gigantol (1, 5, 10 or 20 μmol/L) for 1 h followed by further exposure to high (33.3 mmol/L) glucose for 48 h. Gigantol concentration dependently enhanced cell viability followed by high glucose treatment in MES-13 cells. High glucose induced reactive oxygen species (ROS) generation, malondialdehyde production and glutathione deficiency were recoved in MES-13 cells pretreated with gigantol. High glucose triggered cell apoptosis via the the loss of mitochondrial membrane potential, depletion of adenosine triphosphate, upregulation of caspases 9 and 3, enhancement of cytochrome c release, and subsequent interruption of the Bax/Bcl-2 balance. These detrimental effects were ameliorated by gigantol. High glucose also induced activation of JNK, p38 mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) in MES-13 cells, which were blocked by gigantol. The results suggest that treatment MES-13 cells with gigantol halts high glucose-induced renal dysfunction through the suppression of the ROS/MAPK/NF-κB signaling pathways. Our data are of value to the understanding the mechanism for gigantol, and would benefit the study of drug development or food supplement for diabetes and nephropathy.

Upregulation of miR-335 ameliorates myocardial ischemia reperfusion injury via targeting hypoxia inducible factor 1-alpha subunit inhibitor

MicroRNA-335 (miR-335) is implicated in several pathophysiological processes, including tumorigenesis, lipid metabolism and ischemic stroke; however, whether miR-335 plays a role in modulating myocardial ischemia reperfusion injury (MIRI) is still unknown. This study is aimed to explore the role and mechanism of miR-335 in the pathophysiological process of MIRI. Specifically, miR-335 mimics or a chemically modified agomiR-335 were transfected or injected into H9c2 cells and Wistar rats to upregulate miR-335 expression in vitro and in vivo, respectively. The effects of miR-335 overexpression on hypoxia/reoxygenation (H/R)-treated cardiomyocytes and ischemia/reperfusion (I/R)-exposed heart samples were investigated by a Cell Counting Kit-8 assay, flow cytometry, TTC staining and a TUNEL assay. The target of miR-335 was identified using a luciferase reporter assay. The expression of heme oxygenase 1 (HO-1) and inducible nitric oxide synthase (iNOS) was detected by reverse transcription-quantitative polymerase chain reaction and western blotting. The results showed that miR-335 expression in cardiomyocytes and the myocardium was downregulated during MIRI but was induced by hypoxic/ischemic postconditioning. MiR-335 overexpression led to an increase in cell viability and a reduction in the apoptosis of H/R-treated cardiomyocytes. Meanwhile, myocardial infarct size and the apoptosis of I/R-exposed heart tissues were decreased in response to miR-335 upregulation. Furthermore, we identified that hypoxia inducible factor 1-alpha subunit inhibitor (HIF1AN), a suppressor of hypoxia inducible factor 1-alpha (HIF-1α) stabilization and transcriptional activity, is a novel target of miR-335. MiR-335 overexpression enhanced the transcriptional activity of HIF-1α, increased the expression of HO-1 and iNOS, and inhibited mitochondrial permeability transition pore (MPTP) opening. In conclusion, we are the first to demonstrate that upregulation of miR-335 ameliorates MIRI by targeting HIF1AN. Thus, miR-335 may be a new therapeutic target for the treatment of MIRI.

Effects of environmental cocaine concentrations on the skeletal muscle of the European eel (Anguilla anguilla)

The presence of illicit drugs in the aquatic environment represents a new potential risk for aquatic organisms, due to their constant exposure to substances with strong pharmacological activity. Currently, little is known about the ecological effects of illicit drugs. The aim of this study was to evaluate the influence of environmental concentrations of cocaine, an illicit drug widespread in surface waters, on the skeletal muscle of the European eel (Anguilla anguilla). The skeletal muscle of silver eels exposed to 20 ng L^-1 of cocaine for 50 days were compared to control, vehicle control and two post-exposure recovery groups (3 and 10 days after interruption of cocaine). The eels general health, the morphology of the skeletal muscle and several parameters indicative of the skeletal muscle physiology were evaluated, namely the muscle whole protein profile, marker of the expression levels of the main muscle proteins; cytochrome oxidase activity, markers of oxidative metabolism; caspase-3, marker of apoptosis activation; serum levels of creatine kinase, lactate dehydrogenase and aspartate aminotransferase, markers of skeletal muscle damages. Cocaine-exposed eels appeared hyperactive but they showed the same general health status as the other groups. In contrast, their skeletal muscle showed evidence of serious injury, including muscle breakdown and swelling, similar to that typical of rhabdomyolysis. These changes were still present 10 days after the interruption of cocaine exposure. In fact, with the exception of the expression levels of the main muscle proteins, which remained unchanged, all the other parameters examined showed alterations that persisted for at least 10 days after the interruption of cocaine exposure. This study shows that even low environmental concentrations of cocaine cause severe damage to the morphology and physiology of the skeletal muscle of the silver eel, confirming the harmful impact of cocaine in the environment that potentially affects the survival of this species.

Isosteviol Sodium Protects Neural Cells Against Hypoxia-Induced Apoptosis Through Inhibiting MAPK and NF-κB Pathways

BACKGROUND

Stevioside, isolated from the herb Stevia rebaudiana, has been widely used as a food sweetener all over the world. Isosteviol Sodium (STV-Na), an injectable formulation of isosteviol sodium salt, has been proved to possess much greater solubility and bioavailability and exhibit protective effects against cerebral ischemia injury in vivo by inhibiting neuron apoptosis. However, the underlying mechanisms of the neuroprotective effects STV-Na are still not completely known. In the present study, we investigated the effects of STV-Na on neuronal cell death caused by hypoxia in vitro and its underlying mechanisms.

METHODS

We used cobalt chloride (CoCl₂) to expose mouse neuroblastoma N2a cells to hypoxic conditions in vitro.

RESULTS

Our results showed that pretreatment with STV-Na (20 μM) significantly attenuated the decrease of cell viability, lactate dehydrogenase release and cell apoptosis under conditions of CoCl₂-induced hypoxia. Meanwhile, STV-Na pretreatment significantly attenuated the upregulation of intracellular Ca²⁺ concentration and reactive oxygen species production, and inhibited mitochondrial depolarization in N2a cells under conditions of CoCl₂-induced hypoxia. Furthermore, STV-Na pretreatment significantly downregulated expressions of nitric oxide synthase, interleukin-1β, tumor necrosis factor-α, interleukin-6, nuclear factor kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) signalings in N2a cells under conditions of CoCl₂-induced hypoxia.

CONCLUSIONS

Taken together, STV-Na protects neural cells against hypoxia-induced apoptosis through inhibiting MAPK and NF-κB pathways.

Reprogramming of basic metabolic pathways in microbial sepsis: therapeutic targets at last?

Sepsis is a highly lethal and urgent unmet medical need. It is the result of a complex interplay of several pathways, including inflammation, immune activation, hypoxia, and metabolic reprogramming. Specifically, the regulation and the impact of the latter have become better understood in which the highly catabolic status during sepsis and its similarity with starvation responses appear to be essential in the poor prognosis in sepsis. It seems logical that new interventions based on the recognition of new therapeutic targets in the key metabolic pathways should be developed and may have a good chance to penetrate to the bedside. In this review, we concentrate on the pathological changes in metabolism, observed during sepsis, and the presumed underlying mechanisms, with a focus on the level of the organism and the interplay between different organ systems.

The Effects of Potassium Cyanide on the Functional Recovery of Isolated Rat Hearts after Ischemia and Reperfusion: The Role of Oxidative Stress

This investigation is aimed at examining the effects of pharmacological PostC with potassium cyanide (KCN) on functional recovery, gene expression, cytochrome c expression, and redox status of isolated rat hearts. Rats were divided into the control and KCN groups. The hearts of male Wistar albino rats were retrogradely perfused according to the Langendorff technique at a constant perfusion pressure of 70 cmH₂O. After stabilisation, control hearts were subjected to global ischemia (5 minutes), followed by reperfusion (5 minutes), while experimental hearts underwent global ischemia (5 minutes) followed by 5 minutes of reperfusion with 10 μmol/L KCN. The following parameters of heart function were measured: maximum and minimum rates of pressure development, systolic and diastolic left ventricular pressure, heart rate, and coronary flow. Levels of superoxide anion radical, hydrogen peroxide, nitrites, and index of lipid peroxidation (measured as thiobarbituric acid-reactive substances) were measured in coronary venous effluent, and activity of catalase was determined in heart tissue. Expression of Bax, Bcl-2, SOD-1, SOD-2, and cytochrome c was studied as well. It was shown that expression of Bax, Bcl-2, and SOD-2 genes did not significantly differ between groups, while expression of SOD-1 gene and cytochrome c was lower in the KCN group. Our results demonstrated that KCN improved the recovery of myocardial contractility and systolic and diastolic function, enhanced catalase activity, and diminished generation of prooxidants. However, all possible mechanisms and potential adverse effects of KCN should be further examined in the future.