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

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

S1PR3 inhibition protects against LPS-induced ARDS by inhibiting NF-κB and improving mitochondrial oxidative phosphorylation.

BACKGROUND: Inflammation and endothelial barrier dysfunction are the major pathophysiological changes in acute respiratory distress syndrome (ARDS). Sphingosine-1-phosphate receptor 3 (S1PR3), a G protein-coupled receptor, has been found to mediate inflammation and endothelial cell (EC) integrity. However, the function of S1PR3 in ARDS has not been fully elucidated. METHODS: We used a murine lipopolysaccharide (LPS)-induced ARDS model and an LPS- stimulated ECs model to investigate the role of S1PR3 in anti-inflammatory effects and endothelial barrier protection during ARDS. RESULTS: We found that S1PR3 expression was increased in the lung tissues of mice with LPS-induced ARDS. TY-52156, a selective S1PR3 inhibitor, effectively attenuated LPS-induced inflammation by suppressing the expression of proinflammatory cytokines and restored the endothelial barrier by repairing adherens junctions and reducing vascular leakage. S1PR3 inhibition was achieved by an adeno-associated virus in vivo and a small interfering RNA in vitro. Both the in vivo and in vitro studies demonstrated that pharmacological or genetic inhibition of S1PR3 protected against ARDS by inhibiting the NF-κB pathway and improving mitochondrial oxidative phosphorylation. CONCLUSIONS: S1PR3 inhibition protects against LPS-induced ARDS via suppression of pulmonary inflammation and promotion of the endothelial barrier by inhibiting NF-κB and improving mitochondrial oxidative phosphorylation, indicating that S1PR3 is a potential therapeutic target for ARDS.

Cardiolipin in myocardial ischaemia-reperfusion injury: From molecular mechanisms to clinical strategies.

Myocardial reperfusion injury occurs when blood flow is restored after ischemia, an essential process to salvage ischemic tissue. However, this phenomenon is intricate, characterized by various harmful effects. Tissue damage in ischemia-reperfusion injury arises from various factors, including the production of reactive oxygen species, the sequestration of proinflammatory immune cells in ischemic tissues, the induction of endoplasmic reticulum stress, and the occurrence of postischemic capillary no-reflow. Secretory phospholipase A2 (sPLA2) plays a crucial role in the eicosanoid pathway by releasing free arachidonic acid from membrane phospholipids' sn-2 position. This liberated arachidonic acid serves as a substrate for various eicosanoid biosynthetic enzymes, including cyclooxygenases, lipoxygenases, and cytochromes P450, ultimately resulting in inflammation and an elevated risk of reperfusion injury. Therefore, the activation of sPLA2 directly correlates with the heightened and accelerated damage observed in myocardial ischemia-reperfusion injury (MIRI). Presently, clinical trials are in progress for medications aimed at sPLA2, presenting promising avenues for intervention. Cardiolipin (CL) plays a crucial role in maintaining mitochondrial function, and its alteration is closely linked to mitochondrial dysfunction observed in MIRI. This paper provides a critical analysis of CL modifications concerning mitochondrial dysfunction in MIRI, along with its associated molecular mechanisms. Additionally, it delves into various pharmacological approaches to prevent or alleviate MIRI, whether by directly targeting mitochondrial CL or through indirect means.

Exercise Hemodynamics and Mitochondrial Oxidative Capacity in Disease Stages of Wild-Type Transthyretin Amyloid Cardiomyopathy.

BACKGROUND: Wild-type transthyretin amyloid (ATTRwt) cardiomyopathy is increasingly recognized in the development of heart failure. The link between cardiac performance, hemodynamics, and mitochondrial function in disease stages of ATTRwt has not previously been studied but may provide new insights into the pathophysiology and clinical performance of the patients. METHODS AND RESULTS: The study investigated 47 patients diagnosed with ATTRwt at Aarhus University Hospital, Denmark. Patients were stratified according to the disease stages of the National Amyloidosis Centre (NAC) as NAC I with low levels of NT-proBNP (N-terminal pro-B-type natriuretic peptide) (NAC I-L, n=14), NAC I with high levels NT-proBNP (NAC I-H, n=20), and NAC II-III (n=13). Exercise testing with simultaneous right heart catheterization was performed in all patients. Endomyocardial biopsies were collected from the patients and the mitochondrial oxidative phosphorylation capacity was assessed. All NAC disease groups, even in the NAC I-L group, a significant abnormal increase in biventricular filling pressures were noted during exercise while the filling pressures was normal or near normal at rest. The inotropic response to exercise was reduced with diminished increase in cardiac output which was significantly more pronounced in the NAC I-H (Diff. -2.4, 95% CI (-4.2: -0.7), P=0.00) and the NAC II-III group (Diff: -3.1 L/min, 95% CI (-5.2: -1.1), P=0.00) compared with the NAC I-L group. The pulmonary artery wedge pressure to cardiac output ratio at peak exercise was significantly different between NAC I-L and NAC II-III (Diff: 1.6 mm Hg*min/L, 95% CI (0.01:3.3, P=0.04)). Patients with ATTRwt had a reduced oxidative phosphorylation capacity which correlated to left ventricular mass but not to cardiac output capacity. CONCLUSIONS: An abnormal restrictive left ventricle and right ventricle response to exercise was demonstrated, even present in patients with early-stage ATTRwt. In more advanced disease stages a progressive impairment of the pressure-flow relationship was noted. The myocyte energetics is deranged but not associated to the contractile reserve or restrictive filling characteristics in ATTRwt.

Influence of the interaction between p53 and ZNF568 on mitochondrial oxidative phosphorylation.

The tumor suppressor p53 plays important roles in suppressing the development and progression of cancer by responding to various stress signals. In addition, p53 can regulate the metabolic pathways of cancer cells by regulating energy metabolism and oxidative phosphorylation. Here, we present a mechanism for the interaction between p53 and ZNF568. Initially, we used X-ray crystallography to determine the irregular loop structure of the ZNF568 KRAB domain; this loop plays an important role in the interaction between p53 and ZNF568. In addition, Cryo-EM was used to examine how the p53 DBD and ZNF568 KRAB domains bind together. The function of ZNF568 on p53-mediated mitochondrial respiration was confirmed by measuring glucose consumption and lactate production. These findings show that ZNF568 can reduce p53-mediated mitochondrial respiratory activity by binding to p53 and inhibiting the transcription of SCO2. SIGNIFICANCE: ZNF568 can directly bind to the p53 DBD and transcriptionally regulate the SCO2 gene. SCO2 transcriptional regulation by interaction between ZNF568 and p53 may regulate the balance between mitochondrial respiration and glycolysis.

The down-regulation of GADD45B leads to a conversion of cellular oxidative phosphorylation to glycolysis and promotes the progression of bladder cancer.

Background: The predominant feature of cancer cells during the process of carcinogenesis is the inclination towards glycolytic metabolism rather than mitochondrial oxidative phosphorylation. Nevertheless, there is a scarcity of research investigating the correlation between bladder cancer and mitochondrial energy metabolism. Methods: A qPCR array comprising 90 genes associated with mitochondrial oxidative phosphorylation was employed to discern metabolic disparities between three sets of bladder cancer tissue and adjacent normal tissue. Wound healing and transwell assays were utilized to assess cell migration and invasion capabilities, respectively. Colony formation assays were conducted to ascertain the tumorigenic potential of the cells. The proliferative capacity of the cells was examined through in vitro CCK-8 assays. Additionally, nude mouse models were established to evaluate the impact of bladder tumor cells on in vivo proliferation. The Seahorse XFe96 Analyzer was utilized to quantify mitochondrial oxidative phosphorylation, while the levels of glucose-6-phosphate and pyruvate were assessed to evaluate glycolysis. Results: Examination of qPCR array data demonstrated a noteworthy inhibition of mitochondrial oxidative phosphorylation in bladder cancer tissue, as evidenced by the down-regulation of a majority of genes associated with mitochondrial energy metabolism. Notably, GADD45B may potentially exert a significant influence on bladder cancer development, warranting further investigation. The down-regulation of GADD45B in bladder cancer cells resulted in impaired mitochondrial respiration and elevated levels of glycolysis, thereby enhancing cell migration and invasion. Conversely, up-regulation of GADD45B had the opposite effect. Furthermore, over-expression of GADD45B inhibited tumor proliferation and tumorigenesis in both in vitro and in vivo settings. Conclusion: These findings from our study indicate that the down-regulation of GADD45B promotes the shift of cell mitochondrial oxidative phosphorylation towards glycolysis, thereby facilitating the progression of bladder cancer.

Intermittent fasting improves the oocyte quality of obese mice through the regulation of maternal mRNA storage and translation by LSM14B.

Obesity has significant repercussions for female reproductive health, including adverse effects on oocyte quality, fertility, embryo development and offspring health. Here, we showed that intermittent fasting (IF) has several notable effects on follicular development, oocyte development and maturation and offspring health in obese mice. IF treatment prevents obesity-associated germline-soma communication defects, mitochondrial dysfunction, oxidative damage, apoptosis, and spindle/chromosomal disruption. RNA-sequencing analysis of oocytes from normal diet (ND), high-fat diet (HFD), and HFD + IF mice indicated that IF treatment improved mitochondrial oxidative phosphorylation function and mRNA storage and translation, which was potentially mediated by the Smith-like family member 14 B (LSM14B). Knockdown of LSM14B by siRNA injection in oocytes from ND mice recapitulates all the translation, mitochondrial dysfunction and meiotic defect phenotypes of oocytes from HFD mice. Remarkably, the injection of Lsm14b mRNA into oocytes from HFD mice rescued the translation, mitochondrial dysfunction and meiotic defect phenotypes. These results demonstrated that dysfunction in the oocyte translation program is associated with obesity-induced meiotic defects, while IF treatment increased LSM14B expression and maternal mRNA translation and restored oocyte quality. This research has important implications for understanding the effects of obesity on female reproductive health and offers a potential nonpharmacological intervention to improve oocyte quality and fertility in obese individuals.

Self-Delivery Nanomedicines Reverse Thermal Resistance to Enhance Tumor Mild-Temperature Photothermal Therapy.

Tumoral thermal defense mechanisms considerably attenuate the therapeutic outcomes of mild-temperature photothermal therapy (PTT). Thus, developing a simple, efficient, and universal therapeutic strategy to sensitize mild-temperature PTT is desirable. Herein, we report self-delivery nanomedicines ACy NPs comprising a near-infrared (NIR) photothermal agent (Cypate), mitochondrial oxidative phosphorylation inhibitor (ATO), and distearoylphosphatidylethanolamine-polyethylene glycol 2000 (DSPE-PEG2000), which have a high drug-loading efficiency that can reverse tumoral thermal resistance, thereby increasing mild-temperature PTT efficacy. ACy NPs achieved targeted tumor accumulation and performed NIR fluorescence imaging capability in vivo to guide tumor PTT for optimized therapeutic outcomes. The released ATO reduced intracellular ATP levels to downregulate multiple heat shock proteins (including HSP70 and HSP90) before PTT, which reversed the thermal resistance of tumor cells, contributing to the excellent results of mild-temperature PTT in vitro and in vivo. Therefore, this study provides a simple, biosafe, advanced, and universal heat shock protein-blocking strategy for tumor PTT.

AHR signaling pathway mediates mitochondrial oxidative phosphorylation which leads to cytarabine resistance.

The aryl hydrocarbon receptor (AHR) has been identified as a significant driver of tumorigenesis. However, its clinical significance in acute myeloid leukemia (AML) remains largely unclear. In this study, RNA-Seq data from AML patients (bone marrow samples from 173 newly diagnosed AML patients) obtained from the TCGA database, and normal human RNA-Seq data (bone marrow samples from 70 healthy individuals) obtained from the GTEX database are downloaded for external validation and complementarity. The data analysis reveals that the AHR signaling pathway is activated in AML patients. Furthermore, there is a correlation between the expressions of AHR and mitochondrial oxidative phosphorylation genes. In vitro experiments show that enhancing AHR expression in AML cells increases mitochondrial oxidative phosphorylation and induces resistance to cytarabine. Conversely, reducing AHR expression in AML cells decreases cytarabine resistance. These findings deepen our understanding of the AHR signaling pathway's involvement in AML.

NADPH oxidase overexpression and mitochondrial OxPhos impairment are more profound in human hearts donated after circulatory death than brain death.

This study investigated cardiac stress and mitochondrial oxidative phosphorylation (OxPhos) in human donation after circulatory death (DCD) hearts regarding warm ischemic time (WIT) and subsequent cold storage and compared them with that of human brain death donor (DBD) hearts. A total of 24 human hearts were procured for the research study-6 in the DBD group and 18 in the DCD group. DCD group was divided into three groups (n = 6) based on different WITs (20, 40, and 60 min). All hearts received del Nido cardioplegia before being placed in normal saline cold storage for 6 h. Left ventricular biopsies were performed at hours 0, 2, 4, and 6. Cardiac stress [nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits: 47-kDa protein of phagocyte oxidase (p47phox), 91-kDa glycoprotein of phagocyte oxidase (gp91phox)] and mitochondrial oxidative phosphorylation [OxPhos, complex I (NADH dehydrogenase) subunit of ETC (CI)-complex V (ATP synthase) subunit of ETC (CV)] proteins were measured in cardiac tissue and mitochondria respectively. Modulation of cardiac stress and mitochondrial dysfunction were observed in both DCD and DBD hearts. However, DCD hearts suffered more cardiac stress (overexpressed NADPH oxidase subunits) and diminished mitochondrial OxPhos than DBD hearts. The severity of cardiac stress and impaired oxidative phosphorylation in DCD hearts correlated with the longer WIT and subsequent cold storage time. More drastic changes were evident in DCD hearts with a WIT of 60 min or more. Activation of NADPH oxidase via overproduction of p47phox and gp91phox proteins in cardiac tissue may be responsible for cardiac stress leading to diminished mitochondrial oxidative phosphorylation. These protein changes can be used as biomarkers for myocardium damage and might help assess DCD and DBD heart transplant suitability.NEW & NOTEWORTHY First human DCD heart research studied cardiac stress and mitochondrial dysfunction concerning WIT and the efficacy of del Nido cardioplegia as an organ procurement solution and subsequent cold storage. Mild to moderate cardiac stress and mitochondrial dysfunction were noticed in DCD hearts with WIT 20 and 40 min and cold storage for 4 and 2 h, respectively. These changes can serve as biomarkers, allowing interventions to preserve mitochondria and extend WIT in DCD hearts.

Uniparental Disomy as a Mechanism for Combined Oxidative Phosphorylation Deficiency Associated with MRPS34 Gene.

INTRODUCTION: Mitochondrial oxidative phosphorylation (OXPHOS) is a cellular process that generates most of the cellular energy required by the body. Disorders affecting OXPHOS are multisystem diseases caused by pathogenic variants in more than 50 genes. In 2017, biallelic variants in the MRPS34 gene were shown to cause combined oxidative phosphorylation deficiency type 32 (COPD32) (OMIM#617664); however, only 7 patients have been reported in the literature up to this moment. COPD32 is characterized mainly by a severe Leigh-like syndrome. METHODS: Whole-exome sequencing identified a homozygous pathogenic variant in the MRPS34 gene, c.322-10G>A. Only the mother was heterozygous for this variant. SNP-array analysis was performed, which revealed a region of absence of heterozygosity in variant 16q with 9.8Mb, compatible with maternal uniparental disomy. RESULTS/CASE REPORT: We report the case of an 18-year-old female with unremarkable family history. The pregnancy was complicated by oligohydramnios, and the neonatal period was unremarkable. She evolved with low weight, mild-moderate developmental delay/intellectual disability, and hypogonadotropic hypogonadism. On examination, she had slender habitus, joint laxity, and kyphoscoliosis. The cardiac evaluation was normal, and the head MRI showed bilateral olivary nucleus degeneration that was not confirmed subsequently. Extensive metabolic studies documented only mild lactate and pyruvate elevation, and the chromosomal microarray was normal. CONCLUSION: We have reported the case of the first patient with COPD32 due to partial maternal uniparental disomy of chromosome 16, being first in Portugal and seventh in the literature. Contrarily to previous patients, who died in the first months of life or survived with severe DD/ID, and had a Leigh-like syndrome, this case is significantly milder, contributing to a better characterization of the phenotypic spectrum. Recurrence risk is unexpectedly low in this instance. This case illustrates the importance of segregation analysis in patients with homozygous recessive mutations.

Tigecycline causes loss of cell viability mediated by mitochondrial OXPHOS and RAC1 in hepatocellular carcinoma cells.

BACKGROUND: Despite recent advances in locoregional, systemic, and novel checkpoint inhibitor treatment, hepatocellular carcinoma (HCC) is still associated with poor prognosis. The feasibility of potentially curative liver resection (LR) and transplantation (LT) is limited by the underlying liver disease and a shortage of organ donors. Especially after LR, high recurrence rates present a problem and circulating tumor cells are a major cause of extrahepatic recurrence. Tigecycline, a commonly used glycylcycline antibiotic, has been shown to have antitumorigenic effects and could be used as a perioperative and adjuvant therapeutic strategy to target circulating tumor cells. We aimed to investigate the effect of tigecycline on HCC cell lines and its mechanisms of action. METHODS: Huh7, HepG2, Hep3B, and immortalized hepatocytes underwent incubation with clinically relevant tigecycline concentrations, and the influence on proliferation, migration, and invasion was assessed in two- and three-dimensional in vitro assays, respectively. Bioinformatic analysis was used to identify specific targets of tigecycline. The expression of RAC1 was detected using western blot, RT-PCR and RNA sequencing. ELISA and flow cytometry were utilized to measure reactive oxygen species (ROS) generation upon tigecycline treatment and flow cytometry to detect alterations in cell cycle. Changes in mitochondrial function were detected via seahorse analysis. RNA sequencing was performed to examine involved pathways. RESULTS: Tigecycline treatment resulted in a significant reduction of mitochondrial function with concomitantly preserved mitochondrial size, which preceded the observed decrease in HCC cell viability. The sensitivity of HCC cells to tigecycline treatment was higher than that of immortalized non-cancerous THLE-2 hepatocytes. Tigecycline inhibited both migratory and invasive properties. Tigecycline application led to an increase of detected ROS and an S-phase cell cycle arrest. Bioinformatic analysis identified RAC1 as a likely target for tigecycline and the expression of this molecule was increased in HCC cells as a result of tigecycline treatment. CONCLUSION: Our study provides evidence for the antiproliferative effect of tigecycline in HCC. We show for the first time that this effect, likely to be mediated by reduced mitochondrial function, is associated with increased expression of RAC1. The reported effects of tigecycline with clinically relevant and achievable doses on HCC cells lay the groundwork for a conceivable use of this agent in cancer treatment.

Do the Effects of Krebs Cycle Intermediates on Oxygen-Dependent Processes in Hypoxia Mediated by the Nitric Oxide System Have Reciprocal or Competitive Relationships?

BACKGROUND/AIMS: Currently, it is proven that the cellular metabolism of nitric oxide is necessary to maintain optimal health and adaptation of the organism to the impact of various environmental factors. The aim of this work was to reveal the biological role of nitric oxide, its metabolic changes, and its mechanism of action in tissues under hypoxia, as well as the possibility of tissue metabolism correction through NO-dependent systems under the influence of Krebs cycle intermediates. METHODS: A systematic assessment of the effect of succinate (SC, 50 mg/kg b.w.) and α-ketoglutarate (KGL, 50 mg/kg b.w.) in the regulation of oxygendependent processes in rats (mitochondrial oxidative phosphorylation, microsomal oxidation, intensity of lipid peroxidation processes, and the state of the antioxidant defense system) depending on functional changes in nitric oxide production during hypoxia was evaluated. The state of the nitric oxide system was estimated spectrophotometrically by determination of the concentration of its stable nitrite anion metabolite (NO2 -). The levels of catecholamines were estimated from the content of epinephrine and norepinephrine using the differentially fluorescent method. The activity of cytochrome P450-dependent aminopyrine-N-demethylase was determined with the Nash reagent. RESULTS: Tissue hypoxia and metabolic disorders caused by this condition through changes in the content of catecholamines (epinephrine, norepinephrine, dopamine, DOPA) as well as the cholinesterase-related system (acetylcholine content and acetylcholinesterase activity) were the studied experimental parameters under acute hypoxia (AH, 7% O2 in N2, 30 min). The activation of lipid peroxidation and oxidatively modified proteins and an increase in the epinephrine content in AH are associated with an increased role of SC and a decrease in KGL as substrates of oxidation in mitochondria. A more pronounced effect of exogenous KGL, compared to SC, on the content of nitrite anion as a stable metabolite of nitric oxide in the liver under acute hypoxia against the background of a decrease in the intensity of lipid peroxidation processes was revealed. The activation of SC-dependent mitochondrial oxidative processes caused by AH was found to decrease in animals after an intermittent hypoxia training (IHT) course. IHT (7% O2 in N2, 15-min, 5 times daily, 14 days) prevented the activation of oxidative stress in tissues and blood after the AH impact and increased the efficiency of energy-related reactions in the functioning of hepatic mitochondria through increased oxidation of KGL. CONCLUSION: The studied effects of adaptation are mediated by an increase in the role of NO-dependent mechanisms, as assessed by changes in the pool of nitrates, nitrites, carbamides, and total polyamines.

Isoliquiritigenin inhibits gastric cancer growth through suppressing GLUT4 mediated glucose uptake and inducing PDHK1/PGC-1α mediated energy metabolic collapse.

BACKGROUND: Isoliquiritigenin (ISL), a natural flavonoid, has anti-tumor activity. But, the understanding of the impact and molecular mechanism of ISL on the growth of gastric cancer (GC) remains limited. PURPOSE: The study was to explore the tumor suppressive effect of ISL on GC growth both in vitro and in vivo, meanwhile, clarify its molecular mechanisms. METHODS: Cell viability was detected by cell counting kit-8 (CCK-8) assay. Apoptotic cells in vitro were monitored by Hoechst 33,342 solution. Protein expression was assessed by Western blot. Reactive oxygen species (ROS) level was evaluated by utilizing 2',7'- dichlorofluorescin diacetate (DCFH-DA). Lactic acid level was detected with L-lactate assay kit. Glucose uptake was monitored with fluorescently tagged glucose 2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl)amino]-2-deoxyglucose (2-NBDG). Glycolytic proton efflux rate (GlycoPER) was evaluated by glycolytic rate assay kit. Oxygen consumption rate (OCR) was conducted by mito stress test kit. A nude mouse model of gastric cancer cell xenograft was established by subcutaneous injection with MGC803 cells. Pathological changes were evaluated by using H&E staining. Cell apoptosis in vivo was evaluated by terminal deoxy-nucleotide transferase mediated dUTP nick end labeling (TUNEL) assay. RESULTS: ISL remarkably suppressed GC growth and increased cell apoptosis. It regulated apoptosis-related and metabolism-related protein expression both in vitro and in vivo. ISL blocked glucose uptake and suppressed production and secretion of lactic acid, which was accompanied with suppressed mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis but increased ROS accumulation. Overexpression of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), cellular-myelocytomatosis viral oncogene (c-Myc), hypoxia inducible factor-1α (HIF-1α), glucose transporter 4 (GLUT4) or pyruvate dehydrogenase kinase 1 (PDHK1), could abolish ISL-induced inhibition of cell viability in GC cells. CONCLUSION: These findings implicated that ISL inhibits GC growth by decreasing GLUT4 mediated glucose uptake and inducing PDHK1/PGC-1α-mediated energy metabolic collapse through depressing protein expression of c-Myc and HIF-1α in GC, suggesting its potential application for GC treatment.

Effect of Vaccination on Platelet Mitochondrial Bioenergy Function of Patients with Post-Acute COVID-19.

BACKGROUND: Mitochondrial dysfunction and redox cellular imbalance indicate crucial function in COVID-19 pathogenesis. Since 11 March 2020, a global pandemic, health crisis and economic disruption has been caused by SARS-CoV-2 virus. Vaccination is considered one of the most effective strategies for preventing viral infection. We tested the hypothesis that preventive vaccination affects the reduced bioenergetics of platelet mitochondria and the biosynthesis of endogenous coenzyme Q10 (CoQ10) in patients with post-acute COVID-19. MATERIAL AND METHODS: 10 vaccinated patients with post-acute COVID-19 (V + PAC19) and 10 unvaccinated patients with post-acute COVID-19 (PAC19) were included in the study. The control group (C) consisted of 16 healthy volunteers. Platelet mitochondrial bioenergy function was determined with HRR method. CoQ10, γ-tocopherol, α-tocopherol and ß-carotene were determined by HPLC, TBARS (thiobarbituric acid reactive substances) were determined spectrophotometrically. RESULTS: Vaccination protected platelet mitochondrial bioenergy function but not endogenous CoQ10 levels, in patients with post-acute COVID-19. CONCLUSIONS: Vaccination against SARS-CoV-2 virus infection prevented the reduction of platelet mitochondrial respiration and energy production. The mechanism of suppression of CoQ10 levels by SARS-CoV-2 virus is not fully known. Methods for the determination of CoQ10 and HRR can be used for monitoring of mitochondrial bioenergetics and targeted therapy of patients with post-acute COVID-19.

Glucose Starvation Inhibits Ferroptosis by Activating the LKB1/AMPK Signaling Pathway and Promotes the High Speed Linear Motility of Dairy Goat Sperm.

In mammals, sperm acquire fertilization ability after capacitation in vitro or when in the female reproductive tract. The motility patterns of sperm undergo continuous changes from the moment of ejaculation until fertilization in the female reproductive tract. In vitro, hyperactivated motility can be induced through high glucose mediums, while in vivo, it is induced by oviduct fluids. Conversely, sperm maintain linear motility in seminal plasma or uterine fluids that contain low glucose levels. In dairy goat sperm, energy metabolism associated with capacitation depends on the energy sources in vitro, seminal plasma, or the female reproductive tract, especially the glucose levels. However, there is little experimental knowledge that glucose levels affect sperm energy metabolism in dairy goats. To clarify these hypotheses, we incubated dairy goat spermatozoa with different concentrations of rotenone-glucose (ROT), carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), and tigecycline (TIG) in vitro. Sperm motility attributes, ATP content, pyruvate and lactate levels, mitochondrial permeability transition pore fluorescence intensity, mitochondrial membrane potential (MMP), and protein synthesis were analyzed. Sperm motility patterns changed from circular to linear under low glucose conditions compared with those in high glucose conditions and showed a significant improvement in progressive motility and straight line speed, whereas lactate and pyruvate levels and MMP decreased remarkably. Incubation of spermatozoa with ROT, FCCP, and TIG inhibited sperm mitochondrial activity, protein synthesis, oxidative phosphorylation, and ATP levels, thereby reducing sperm motility, including the progressive motility, straight line speed, and total motility. Simultaneously, incubation of spermatozoa with Compound C under low glucose conditions significantly decreased the ATP levels and MMP, as well as liver kinase B1 and AMPK protein expression. Under low glucose conditions, sperm mainly produce ATP through mitochondrial OXPHOS to achieve high speed linear movement, inhibit ferroptosis through the LKB1/AMPK signaling pathway, and further maintain energy metabolism homeostasis.

PTMA binds to HMGB1 to regulate mitochondrial oxidative phosphorylation and thus affect the malignant progression of esophageal squamous cell carcinoma.

Background: Esophageal squamous cell carcinoma (ESCC) is a malignant tumor of the digestive tract with complex pathogenesis. There is a pressing need to search for ESCC targeted therapy sites and explore its pathogenesis. Prothymosin alpha (PTMA) is abnormally expressed in numerous tumors and has a significant regulatory effect on tumor malignant progression. However, the regulatory role and mechanism of PTMA in ESCC have not yet been reported. Methods: We first detected the PTMA expression in ESCC patients, subcutaneous tumor xenograft models of ESCC, and ESCC cells. Subsequently, PTMA expression in ESCC cells was inhibited by cell transfection, and cell proliferation and apoptosis were detected by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU) staining, flow cytometry, and Western blot. A dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay was used to detect reactive oxygen species (ROS) level in cells, and MitoSOX fluorescent probe, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-benzimidazolyl carbocyanine iodide (JC-1) staining, mitochondrial complex kit, and Western blot were used to detect the expression of mitochondrial oxidative phosphorylation. Next, the combination between PTMA and high mobility group box 1 (HMGB1) was detected using Co-immunoprecipitation (co-IP) and immunofluorescence (IF) techniques. Finally, the expression of PTMA was inhibited and the expression of HMGB1 was overexpressed in cells via cell transfection, and the regulatory effect of PTMA and HMGB1 binding on mitochondrial oxidative phosphorylation in ESCC was determined through related experiments. Results: The expression of PTMA in ESCC was abnormally elevated. The inhibition of PTMA expression in ESCC cells significantly decreased the activity of ESCC cells and increased their apoptosis. Moreover, interference with PTMA can induce ROS aggregation in ESCC cells by inhibiting mitochondrial oxidative phosphorylation, which may be achieved by binding to HMGB1. Conclusions: PTMA binds to HMGB1 to regulate mitochondrial oxidative phosphorylation, thereby affecting the malignant progression of ESCC.

Metabolic shift and the effect of mitochondrial respiration on the osteogenic differentiation of dental pulp stem cells.

Background: Metabolism shifts from glycolysis to mitochondrial oxidative phosphorylation are vital during the differentiation of stem cells. Mitochondria have a direct function in differentiation. However, the metabolic shift and the effect of mitochondria in regulating the osteogenic differentiation of human dental pulp stem cells (hDPSCs) remain unclear. Methods: Human dental pulp stem cells were collected from five healthy donors. Osteogenic differentiation was induced by osteogenic induction medium. The activities of alkaline phosphatase, hexokinase, pyruvate kinase, and lactate dehydrogenase were analyzed by enzymatic activity kits. The extracellular acidification rate and the mitochondrial oxygen consumption rate were measured. The mRNA levels of COL-1, ALP, TFAM, and NRF1 were analyzed. The protein levels of p-AMPK and AMPK were detected by western blotting. Results: Glycolysis decreased after a slight increase, while mitochondrial oxidative phosphorylation continued to increase when cells grew in osteogenic induction medium. Therefore, the metabolism of differentiating cells switched to mitochondrial respiration. Next, inhibiting mitochondrial respiration with carbonyl cyanide-chlorophenylhydrazone, a mitochondrial uncoupler inhibited hDPSCs differentiation with less ALP activity and decreased ALP and COL-1 mRNA expression. Furthermore, mitochondrial uncoupling led to AMPK activation. 5-Aminoimidazole-4-carboxamide ribonucleotide, an AMPK activator, simulated the effect of mitochondrial uncoupling by inhibiting osteogenic differentiation, mitochondrial biogenesis, and mitochondrial morphology. Mitochondrial uncoupling and activation of AMPK depressed mitochondrial oxidative phosphorylation and inhibited differentiation, suggesting that they may serve as regulators to halt osteogenic differentiation from impaired mitochondrial oxidative phosphorylation.

Regulative Roles of Metabolic Plasticity Caused by Mitochondrial Oxidative Phosphorylation and Glycolysis on the Initiation and Progression of Tumorigenesis.

One important feature of tumour development is the regulatory role of metabolic plasticity in maintaining the balance of mitochondrial oxidative phosphorylation and glycolysis in cancer cells. In recent years, the transition and/or function of metabolic phenotypes between mitochondrial oxidative phosphorylation and glycolysis in tumour cells have been extensively studied. In this review, we aimed to elucidate the characteristics of metabolic plasticity (emphasizing their effects, such as immune escape, angiogenesis migration, invasiveness, heterogeneity, adhesion, and phenotypic properties of cancers, among others) on tumour progression, including the initiation and progression phases. Thus, this article provides an overall understanding of the influence of abnormal metabolic remodeling on malignant proliferation and pathophysiological changes in carcinoma.

Porphyromonas gingivalis promotes malignancy and chemo-resistance via GSK3ß-mediated mitochondrial oxidative phosphorylation in human esophageal squamous cell carcinoma.

Our prior studies have confirmed that long-term colonization of Porphyromonas gingivalis (Pg) and overexpression of the inflammatory factor glycogen synthase kinase 3ß (GSK3ß) promote the malignant evolution of esophageal squamous cell carcinoma (ESCC). We aimed to investigate the functional mechanism by which Pg could promote ESCC malignancy and chemo-resistance through GSK3ß-mediated mitochondrial oxidative phosphorylation (mtOXPHOS), and the clinical implications. The effects of Pg and GSK3ß on mtOXPHOS, malignant behaviors and response to paclitaxel and cisplatin treatment of ESCC cells were evaluated by in vitro and in vivo studies. The results showed that Pg induced high expression of the GSK3ß protein in ESCC cells and promoted the progression and chemo-resistance via GSK3ß-mediated mtOXPHOS in human ESCC. Then, Pg infection and the expression of GSK3ß, SIRT1 and MRPS5 in ESCC tissues were detected, and the correlations between each index and postoperative survival of ESCC patients were analysed. The results showed that Pg-positive ESCC patients with high-expression of GSK3ß, SIRT1 and MRPS5 have significant short postoperative survival. In conclusion, we demonstrated that the effective removal of Pg and inhibition of its promotion of GSK3ß-mediated mtOXPHOS may provide a new strategy for ESCC treatment and new insights into the aetiology of ESCC.