Cell Mitochondrial Function Research Articles

Fluorescence Imaging of Mitochondrial DNA Base Excision Repair Reveals Dynamics of Oxidative Stress Responses.

Mitochondrial function in cells declines with aging and with neurodegeneration, due in large part to accumulated mutations in mitochondrial DNA (mtDNA) that arise from deficient DNA repair. However, measuring this repair activity is challenging. We employ a molecular approach for visualizing mitochondrial base excision repair (BER) activity in situ by use of a fluorescent probe (UBER) that reacts rapidly with AP sites resulting from BER activity. Administering the probe to cultured cells revealed signals that were localized to mitochondria, enabling selective observation of mtDNA BER intermediates. The probe showed elevated DNA repair activity under oxidative stress, and responded to suppression of glycosylase activity. Furthermore, the probe illuminated the time lag between the initiation of oxidative stress and the initial step of BER. Absence of MTH1 in cells resulted in elevated demand for BER activity upon extended oxidative stress, while the absence of OGG1 activity limited glycosylation capacity.

Prenatal acoustic programming of mitochondrial function for high temperatures in an arid-adapted bird.

Sound is an essential source of information in many taxa and can notably be used by embryos to programme their phenotypes for postnatal environments. While underlying mechanisms are mostly unknown, there is growing evidence for the involvement of mitochondria—main source of cellular energy (i.e. ATP)—in developmental programming processes. Here, we tested whether prenatal sound programmes mitochondrial metabolism. In the arid-adapted zebra finch, prenatal exposure to ‘heat-calls’—produced by parents incubating at high temperatures—adaptively alters nestling growth in the heat. We measured red blood cell mitochondrial function, in nestlings exposed prenatally to heat- or control-calls, and reared in contrasting thermal environments. Exposure to high temperatures always reduced mitochondrial ATP production efficiency. However, as expected to reduce heat production, prenatal exposure to heat-calls improved mitochondrial efficiency under mild heat conditions. In addition, when exposed to an acute heat-challenge, LEAK respiration was higher in heat-call nestlings, and mitochondrial efficiency low across temperatures. Consistent with its role in reducing oxidative damage, LEAK under extreme heat was also higher in fast growing nestlings. Our study therefore provides the first demonstration of mitochondrial acoustic sensitivity, and brings us closer to understanding the underpinning of acoustic developmental programming and avian strategies for heat adaptation.

Pharmacological Inhibition of NOX4 Improves Mitochondrial Function and Survival in Human Beta-Cells.

Previous studies have reported beneficial effects of NADPH oxidase 4 (NOX4) inhibition on beta-cell survival in vitro and in vivo. The mechanisms by which NOX4 inhibition protects insulin producing cells are, however, not known. The aim of the present study was to investigate the effects of a pharmacological NOX4 inhibitor (GLX7013114) on human islet and EndoC-βH1 cell mitochondrial function, and to correlate such effects with survival in islets of different size, activity, and glucose-stimulated insulin release responsiveness. We found that maximal oxygen consumption rates, but not the rates of acidification and proton leak, were increased in islets after acute NOX4 inhibition. In EndoC-βH1 cells, NOX4 inhibition increased the mitochondrial membrane potential, as estimated by JC-1 fluorescence; mitochondrial reactive oxygen species (ROS) production, as estimated by MitoSOX fluorescence; and the ATP/ADP ratio, as assessed by a bioluminescent assay. Moreover, the insulin release from EndoC-βH1 cells at a high glucose concentration increased with NOX4 inhibition. These findings were paralleled by NOX4 inhibition-induced protection against human islet cell death when challenged with high glucose and sodium palmitate. The NOX4 inhibitor protected equally well islets of different size, activity, and glucose responsiveness. We conclude that pharmacological alleviation of NOX4-induced inhibition of beta-cell mitochondria leads to increased, and not decreased, mitochondrial ROS, and this was associated with protection against cell death occurring in different types of heterogeneous islets. Thus, NOX4 inhibition or modulation may be a therapeutic strategy in type 2 diabetes that targets all types of islets.

Mitochondria as a possible target for cerebral amyloid angiopathy-mediated endothelial dysfunction in the presence of hyperhomocysteinemia.

Cardiovascular (CV) risk factors may potentiate cerebral amyloid angiopathy (CAA) pathology and neurovascular dysfunction, worsening neurodegeneration. The role of the mitochondria, key regulators of cell survival and death, in mediating cerebral endothelial cell (EC) dysfunction during CAA complicated with CV risk factors is unknown. Our lab has demonstrated that carbonic anhydrase inhibitors (CAi) reduce amyloid-induced cell death and mitochondrial dysfunction in EC. Here, we aim to understand the role of the mitochondria in the pathogenesis of mixed AD and vascular dementias. Furthermore, we seek to understand the effects of pan-CAi and CAi with high selectivity for mitochondria-localized isoforms (mCAi) in preventing the toxic effects of amyloid β (Aβ) and hyperhomocysteinemia (HHcy). Human ECs were challenged with Aβ, Hcy, or the combination in the presence or absence of CAi. Cell death, mitochondrial function, and blood-brain barrier (BBB) resistance effects were evaluated. The presence of Aβ and/or HHcy induced EC apoptosis, mediated by death receptors activation and mitochondrial dysfunction, and attenuated by CAi and mCAi. BBB permeability was increased by both Aβ and HHcy, and HHcy worsened amyloid-induced barrier permeability. These effects were prevented by CAi and mCAi. Both HHcy and Aβ had detrimental effects on EC mitochondrial function and BBB permeability, and HHcy worsened the effects of Aβ. These effects were prevented by CAi and mCAi. The ability of mCAi to protect against Aβ and/or HHcy suggests a central role of the mitochondria in mediating vascular dysfunction in the presence of Aβ and/or HHcy. Our studies support the importance of better understanding mitochondrial and EC pathways responsible for cerebrovascular dysfunction in CAA and mixed dementias.

Antiphospholipid Antibodies From Women With Pregnancy Morbidity and Vascular Thrombosis Induce Endothelial Mitochondrial Dysfunction, mTOR Activation, and Autophagy.

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by thrombosis and pregnancy morbidity (PM) obstetric events together with persistent high titers of circulating antiphospholipid antibodies (aPL). Several mechanisms that explain the development of thrombosis and PM in APS include the association of aPL with alterations in the coagulation cascade and inflammatory events. Other mechanisms disturbing cellular homeostases, such as mitochondrial dysfunction, autophagy, and cell proliferation, have been described in other autoimmune diseases. Therefore, the objective of this study was to investigate the impact of aPL from different patient populations on endothelial cell mitochondrial function, activation of the mammalian target of rapamycin (mTOR) and autophagy pathways, and cellular growth. Using an in vitro model, human umbilical vein endothelial cells (HUVECs) were treated with polyclonal immunoglobulin G (IgG) purified from the serum of women with both PM and vascular thrombosis (PM/VT), with VT only (VT), or with PM and non-criteria aPL (seronegative-obstetric APS, SN-OAPS). We included IgG from women with PM without aPL (PM/aPL-) and healthy women with previous uncomplicated pregnancies (normal human serum, NHS) as control groups. Mitochondrial function, mTOR activation, autophagy, and cell proliferation were evaluated by Western blotting, flow cytometry, and functional assays. IgG from women with PM/VT increased HUVEC mitochondrial hyperpolarization and activation of the mTOR and autophagic pathways, while IgG from patients with VT induced endothelial autophagy and cell proliferation in the absence of elevated mTOR activity or mitochondrial dysfunction. IgG from the SN-OAPS patient group had no effect on any of these HUVEC responses. In conclusion, aPL from women with PM and vascular events induce cellular stress evidenced by mitochondrial hyperpolarization and increased activation of the mTOR and autophagic pathways which may play a role in the pathogenesis of obstetric APS.

Abnormal mitochondrial structure and function are retained in gingival tissues and human gingival fibroblasts from patients with chronic periodontitis.

The abnormal structure and function of mitochondria in cells is closely associated with inflammatory diseases. However, the physiology of mitochondria within gingival tissues and human gingival fibroblasts (HGFs) in patients with chronic periodontitis (CP) remains unclear. The objective of this study was to investigate the structure profile and function of mitochondria in gingival tissues and in HGFs derived from patients with or without CP. These features of mitochondria in HGFs were further analyzed when HGFs were induced by lipopolysaccharide (LPS) from Porphyromonas gingivalis (P.g). Gingival tissues and HGFs were collected from CP and healthy patients. Mitochondrial structure was assessed by transmission electron microscopy. Tissues or cells lysis was performed for mitochondrial DNA (mtDNA) quantification, and real-time polymerase chain reaction (RT-PCR) tests were used to determine mtDNA copy numbers. Western blot analysis was used to evaluate autophagy-related protein (ATG)-5, microtubule-associated protein light chain 3 (LC3), and mitochondrial matrix protein pyruvate dehydrogenase kinase isozyme 2 (PDK2) levels in tissues and HGFs from CP and healthy individuals. Tissues and HGFs from CP showed a significant greater mitochondrial structure destruction, lower mtDNA level, increased ATG5, LC3-II, and lower PDK2 protein levels than those of healthy individuals. In addition, LPS from P.g also triggered the same results in HGFs from healthy donors. Moreover, the challenge of HGFs from CP with LPS worsened these parameters. Mitochondrial structure and function within gingival tissues and HGFs from CP individuals were abnormal compared to those from healthy donors, and LPS could promote mitochondrial destruction.

MyD88 deficiency ameliorates weight loss caused by intestinal oxidative injury in an autophagy-dependent mechanism.

BackgroundGut health plays a vital role in the overall health and disease control of human and animals. Intestinal oxidative stress is a critical player in the induction and progression of cachexia which is conventionally diagnosed and classified by weight loss. Therefore, reduction of intestinal oxidative injury is a common and highly effective strategy for the maintenance of human and animal health. Here we identify intestinal myeloid differentiation primary response gene 88 (MyD88) as a novel target for intestinal oxidative stress using canonical oxidative stress model induced by paraquat (PQ) in vitro and in vivo.MethodsIntestinal oxidative stress was induced by administration of PQ in intestinal epithelial cells (IECs) and mouse model. Cell proliferation, apoptosis, DNA damage, mitochondrial function, oxidative status, and autophagy process were measured in wild‐type and MyD88‐deficient IECs during PQ exposure. Autophagy inhibitor (3‐methyladenine) and activator (rapamycin) were employed to assess the role of autophagy in MyD88‐deficient IECs during PQ exposure. MyD88 specific inhibitor, ST2825, was used to verify function of MyD88 during PQ exposure in mouse model.ResultsMyD88 protein levels and apoptotic rate of IECs are increased in response to PQ exposure (P < 0.001). Intestinal deletion of MyD88 blocks PQ‐induced apoptosis (~42% reduction) and DNA damage (~86% reduction), and improves mitochondrial fission (~37% reduction) and function including mitochondrial membrane potential (~23% increment) and respiratory metabolism capacity (~26% increment) (P < 0.01). Notably, there is a marked decrease in reactive oxygen species in MyD88‐deficient IECs during PQ exposure (~70% reduction), which are consistent with high activity of antioxidative enzymes (~83% increment) (P < 0.001). Intestinal ablation of MyD88 inhibits mTOR signalling, and further phosphorylates p53 proteins during PQ exposure, which eventually promotes intestinal autophagy (~74% increment) (P < 0.01). Activation of autophagy (rapamycin) promotes IECs growth as compared with 3‐methyladenine‐treatment during PQ exposure (~173% increment), while inhibition of autophagy (3‐methyladenine) exacerbates oxidative stress in MyD88‐deficient IECs (P < 0.001). In mouse model, inhibition of MyD88 using specific inhibitor ST2825 followed by PQ treatment effectively ameliorates weight loss (~4% increment), decreased food intake (~92% increment), gastrocnemius and soleus loss (~24% and ~20% increment, respectively), and intestinal oxidative stress in an autophagy dependent manner (P < 0.01).ConclusionsMyD88 modulates intestinal oxidative stress in an autophagy‐dependent mechanism, which suggests that reducing MyD88 level may constitute a putative therapeutic target for intestinal oxidative injury‐induced weight loss.

Abstract 12681: Implication of Aurora Kinase B in Pulmonary Arterial Hypertension

Objective: Pulmonary arterial hypertension (PAH) is a vascular disease characterized by a progressive remodelling of pulmonary arteries (PAs). This leads to an elevation in PA pressure and resistance, leading to right heart failure and death. Nowadays, it is recognized that PA smooth muscle cells (PASMCs) are key actors in the histopathological changes in PAH. As seen in cancer cells, PASMCs exhibit a pro-proliferative and anti-apoptotic cancer-like phenotype, sustained by an important metabolic switch known as Warburg effect. Aurora kinase B (AURKB) is strongly involved in cell proliferation, apoptosis and metabolism by controlling cell cycle activation and mitochondrial functions. Previous research has shown that AURKB is overexpressed in various human cancers and its inhibition repressed tumor progression both in vivo and in vitro, suggesting that it could be a novel therapeutic target in PAH. We thus hypothesized that AURKB is upregulated in PAH and contributes to PAH-PASMCs proliferation and resistance to apoptosis, inhibition of which may reverse PA remodeling. Methods/Results: Using Western blot (WB), we demonstrated a FOXM1-dependent upregulation of AURKB in PASMCs isolated from PAH patients compared to controls (p&lt;0.05 ; n=8-14). Similar results were found in the monocrotaline (MCT) and sugen-hypoxia (Su/Hx) rat models (p&lt;0.05 ; n=11-22). In vitro, we found that pharmacological inhibition of AURKB significantly decreases PAH-PASMC proliferation (EdU incorporation, Ki67 labeling) as well as resistance to apoptosis (Annexin V assay) (p&lt;0.05 ; n=6). We also demonstrated that inhibition of AURKB decreases pro-survival factors such as Survivin and PLK1 and increases apoptosis and cell cycle arrest factors including P21, P27, and P53 (WB; p&lt;0.05 ; n=6). As expected, inhibition of AURKB in PAH-PASMCs was associated with a dose-dependent decrease of phosphohistone H3 expression, a well-known target of AURKB (p&lt;0.05 ; n=6). The therapeutic potential of Barasertib, a clinically available and specific AURKB inhibitor, is currently investigated in both MCT and Su/Hx models. Conclusion: Our preliminary data suggests the contribution of AURKB in PA remodeling and the great potential of using AURKB inhibitors to reverse PAH development.

Abstract 13136: Immune Cell Mitochondrial Function and Diastolic Function in Patients With Heart Failure With Preserved Ejection Fraction

Background: Systemic, multimorbidity-driven inflammation may promote diastolic dysfunction in HFpEF. In this regard, anti-inflammatory therapies have been an attractive treatment strategy in clinical trials of HFpEF. Metabolic reprogramming of immune cells that alter the mitochondrial bioenergetic profile may be an upstream mediator of inflammation. Our aim was to investigate the relationship between the immune cell bioenergetic profile and diastolic function in HFpEF. Methods: Nine female patients with a diagnosis of HFpEF (4 Black, 5 White; Median [IQR]: Age 60 [46-67] yrs; BMI 37 [34-42] kg/m 2 ) were enrolled. The mitochondrial bioenergetic profile was assessed in isolated peripheral blood mononuclear cells by respirometry coupled with modulators of cellular respiration to obtain basal respiration, ATP-linked respiration, maximal respiration and non-mitochondrial respiration. Transthoracic echocardiographic Doppler measures of diastolic function were performed and included mitral inflow velocities (E wave) and early diastolic mitral annular velocity (e’). Results: Diastolic function, represented by E/e’ (Median [IQR]: 10 [8-10] was inversely associated with basal respiration ( r =-0.78, p=0.01), maximal respiration ( r =-0.87, p =0.002), ATP linked respiration (54 [40-105] pmol/min, r =-0.75, p =0.02), non-mitochondrial oxygen consumption (24 [20-35] pmol/min, r =-0.82, p =0.007) and spare respiratory capacity (r=-0.82, p=0.007) as shown in Figure 1. Conclusion: There is a strong negative association between the immune cell mitochondrial bioenergetic profile and diastolic function in HFpEF. Patients with greater impairment in diastolic function, as shown by higher E/e’ ratios, have lower immune cell respiration and reduced respiratory reserve. The relationship between immune cell mitochondrial function, inflammation and diastolic function in HFpEF patients warrants further investigation.

Rotenone-Induced Neurodegeneration Is Enabled by a p38-Parkin-ROS Signaling Feedback Loop.

Rotenone, a component of pesticides, is widely used in agriculture and potentially causes Parkinson's disease (PD). However, the regulatory mechanisms of rotenone-induced PD are unclear. Here, we revealed a novel feedback mechanism of p38-Parkin-ROS regulating rotenone-induced PD. Rotenone treatment led to not only the activation of p38 but also Parkin inactivation and reactive oxygen species (ROS) overproduction in SN4741 cells. Meanwhile, p38 activation regulated Parkin phosphorylation at serine 131 to disrupt Parkin-mediated mitophagy. Notably, both p38 inhibition and Parkin overexpression decreased ROS levels. Additionally, the ROS inhibitor N-acetyl-l-cysteine (NAC) inhibited p38 and activated Parkin-mediated mitophagy. Both p38 inhibition and the ROS inhibitor NAC exerted a protective effect by restoring cell death and mitochondrial function in rotenone-induced PD models. Based on these results, the p38-Parkin-ROS signaling pathway is involved in neurodegeneration. This pathway represents a valuable treatment strategy for rotenone-induced PD, and our study provides basic research evidence for the safe use of rotenone in agriculture.

Tafazzin deficiency impairs mitochondrial metabolism and function of lipopolysaccharide activated B lymphocytes in mice.

B lymphocytes are responsible for humoral immunity and play a key role in the immune response. Optimal mitochondrial function is required to support B cell activity during activation. We examined how deficiency of tafazzin, a cardiolipin remodeling enzyme required for mitochondrial function, alters the metabolic activity of B cells and their response to activation by lipopolysaccharide in mice. B cells were isolated from 3-month-old wild type or tafazzin knockdown mice and incubated for up to 72h with lipopolysaccharide and cell proliferation, expression of cell surface markers, secretion of antibodies and chemokines, proteasome and immunoproteasome activities, and metabolic function determined. In addition, proteomic analysis was performed to identify altered levels of proteins involved in survival, immunogenic, proteasomal and mitochondrial processes. Compared to wild type lipopolysaccharide activated B cells, lipopolysaccharide activated tafazzin knockdown B cells exhibited significantly reduced proliferation, lowered expression of cluster of differentiation 86 and cluster of differentiation 69 surface markers, reduced secretion of immunoglobulin M antibody, reduced secretion of keratinocytes-derived chemokine and macrophage-inflammatory protein-2, reduced proteasome and immunoproteasome activities, and reduced mitochondrial respiration and glycolysis. Proteomic analysis revealed significant alterations in key protein targets that regulate cell survival, immunogenicity, proteasomal processing and mitochondrial function consistent with the findings of the above functional studies. The results indicate that the cardiolipin transacylase enzyme tafazzin plays a key role in regulating mouse B cell function and metabolic activity during activation through modulation of mitochondrial function.

Multi-level fingerprinting and cardiomyocyte protection evaluation for comparing polysaccharides from six Panax herbal medicines

The role of polysaccharides in quality control of ginseng is underestimated. Large-scale comparison on the polysaccharides of Panax ginseng (PG), P. quinquefolius (PQ), P. notoginseng (PN), Red ginseng (RG), P. japonicus (ZJS), and P. japonicus var. major (ZZS), was performed by both chemical and biological approaches. Holistic fingerprinting at polysaccharide and the hydrolyzed oligosaccharide and monosaccharide levels utilized various chromatography methods, while OGD and OGD/R models on H9c2 cells were introduced to evaluate the protective effects on cell viability and mitochondrial function. Polysaccharides from six ginseng species exhibited remarkable content difference (RG > PG/ZZS/ZJS/PQ > PN), but weak differentiations in molecular weight distribution and oligosaccharide profiles, while Glc and GalA were richer for monosaccharide compositions of PG and RG polysaccharides, respectively. RG polysaccharides (25/50/100 μg/mL) showed significant cardiomyocyte protection by regulating mitochondrial functions. These new evidences may provide support for the supplementary role of polysaccharides in quality control of ginseng.

Heterogeneity in the transcriptional response of the human pathogen Aspergillus fumigatus to the antifungal agent caspofungin.

Aspergillus fumigatus is the main causative agent of invasive pulmonary aspergillosis (IPA), a severe disease that affects immunosuppressed patients worldwide. The fungistatic drug caspofungin (CSP) is the second line of therapy against IPA but has increasingly been used against clinical strains that are resistant to azoles, the first line antifungal therapy. In high concentrations, CSP induces a tolerance phenotype with partial reestablishment of fungal growth called CSP paradoxical effect (CPE), resulting from a change in the composition of the cell wall. An increasing number of studies has shown that different isolates of A. fumigatus exhibit phenotypic heterogeneity, including heterogeneity in their CPE response. To gain insights into the underlying molecular mechanisms of CPE response heterogeneity, we analyzed the transcriptomes of two A. fumigatus reference strains, Af293 and CEA17, exposed to low and high CSP concentrations. We found that there is a core transcriptional response that involves genes related to cell wall remodeling processes, mitochondrial function, transmembrane transport, and amino acid and ergosterol metabolism, and a variable response related to secondary metabolite (SM) biosynthesis and iron homeostasis. Specifically, we show here that the overexpression of a SM pathway that works as an iron chelator extinguishes the CPE in both backgrounds, whereas iron depletion is detrimental for the CPE in Af293 but not in CEA17. We next investigated the function of the transcription factor CrzA, whose deletion was previously shown to result in heterogeneity in the CPE response of the Af293 and CEA17 strains. We found that CrzA constitutively binds to and modulates the expression of several genes related to processes involved in CSP tolerance and that crzA deletion differentially impacts the SM production and growth of Af293 and CEA17. As opposed to the ΔcrzACEA17 mutant, the ΔcrzAAf293 mutant fails to activate cell wall remodeling genes upon CSP exposure, which most likely severely affects its macrostructure and extinguishes its CPE. This study describes how heterogeneity in the response to an antifungal agent between A. fumigatus strains stems from heterogeneity in the function of a transcription factor and its downstream target genes.

Effects of peroxisome proliferator activated receptor gamma (PPARγ) agonist on fasting model applied neuron cultures

Abstract Objectives Peroxisome proliferator activated receptor gamma (PPARγ) agonists used for the treatment of Diabetes Mellitus (DM), has important roles on the regulation of metabolism including ketogenesis in fasting and low glucose states. Recently PPARγ was proven to have anti-oxidant and anti-inflammatory effects on neuronal cells. Methods In the present study, effects of pioglitazone (PPARγ agonist) on cell survival, energy metabolism and mitochondrial functions were investigated in glucose deprived fasting model applied SH-SY5Y (ATCC/CRL 2266) cell lines. Before and after pioglitazone treatment; energy metabolites (glucose, lactate, ketone (βOHB), lactate dehydrogenase activity), mitochondrial citrate synthase activity and cell viability were investigated. Results and Conclusions PPARγ agonist addition to glucose deprived, ketone added neurons provided positive improvements in energy metabolites (p&lt;0.01), mitochondrial functions (p&lt;0.001) and survival rates (p&lt;0.01). Changes in mitochondrial citrate synthase activity, lactate and LDH levels of neuronal cells treated with PPARγ agonist have not been previously shown. Our results suggest, pioglitazone as an effective alternative for the treatment of neurodegenerative diseases especially with the presence of ketone bodies. By clarifying the mechanisms of PPARγ agonists, a great contribution will be made to the treatment of neurodegenerative diseases.

Melatonin mitigates Chloroquine-induced defects in porcine immature Sertoli cells

Chloroquine (CQ) could function as a lysosomotropic agent to inhibit the endolysosomal trafficking in the autophagy pathway, and is widely used on malarial, tumor and recently COVID-19. However, the effect of CQ treatment on porcine immature Sertoli cells (iSCs) remains unclear. Here we showed that CQ could reduce iSC viability in a dose-dependent manner. CQ treatment (20 μM) on iSCs for 36h could elevate oxidative stress, damage mitochondrial function and promote apoptosis, which could be partially rescued by melatonin (MT) (10 nM). Transcriptome profiling identified 1611 differentially expressed genes (DEGs) (776 up- and 835 down-regulated) (20 μM CQ vs. DMSO), mainly involved in MAPK cascade, cell proliferation/apoptosis, HIF-1, PI3K-Akt and lysosome signaling pathways. In contrast, only 467 (224 up- and 243 down-regulated) DEGs (CQ + MT vs. DMSO) could be found after MT (10 nM) addition, enriched in cell cycle, regulation of apoptotic process, lysosome and reproduction pathways. Therefore, the partial rescue effects of MT on CQ treatment were confirmed by multiple assays (cell viability, ROS level, mitochondrial function, apoptosis, and mRNA levels of selected genes). Collectively, CQ treatment could impair porcine iSC viability by deranging the signaling pathways related to apoptosis and autophagy, which could be partially rescued by MT supplementation.

LSD1-Demethylated LINC01134 Confers Oxaliplatin Resistance Through SP1-Induced p62 Transcription in HCC.

Oxaliplatin (OXA) is one of the most common chemotherapeutics in advanced hepatocellular carcinoma (HCC), the resistance of which poses a big challenge. Long noncoding RNAs (lncRNAs) play vital roles in chemoresistance. Therefore, elucidating the underlying mechanisms and identifying predictive lncRNAs for OXA resistance is needed urgently. RNA sequencing (RNA-seq) and fluorescence in situ hybridization (FISH) were used to investigate the OXA-resistant (OXA-R) lncRNAs. Survival analysis was performed to determine the clinical significance of homo sapiens long intergenic non-protein-coding RNA 1134 (LINC01134) and p62 expression. Luciferase, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), and chromatin isolation by RNA purification (ChIRP) assays were used to explore the mechanisms by which LINC01134 regulates p62 expression. The effects of LINC01134/SP1/p62 axis on OXA resistance were evaluated using cell viability, apoptosis, and mitochondrial function and morphology analysis. Xenografts were used to estimate the in vivo regulation of OXA resistance by LINC01134/SP1/p62 axis. ChIP, cell viability, and xenograft assays were used to identify the demethylase for LINC01134 up-regulation in OXA resistance. LINC01134 was identified as one of the most up-regulated lncRNAs in OXA-R cells. Higher LINC01134 expression predicted poorer OXA therapeutic efficacy. LINC01134 activates anti-oxidative pathway through p62 by recruiting transcription factor SP1 to the p62 promoter. The LINC01134/SP1/p62 axis regulates OXA resistance by altering cell viability, apoptosis, and mitochondrial homeostasis both in vitro and in vivo. Furthermore, the demethylase, lysine specific demethylase 1 (LSD1) was responsible for LINC01134 up-regulation in OXA-R cells. In patients with HCC, LINC01134 expression was positively correlated with p62 and LSD1 expressions, whereas SP1 expression positively correlated with p62 expression. LSD1/LINC01134/SP1/p62 axis is critical for OXA resistance in HCC. Evaluating LINC01134 expression in HCC will be effective in predicting OXA efficacy. In treatment-naive patients, targeting the LINC01134/SP1/p62 axis may be a promising strategy to overcome OXA chemoresistance.

Deletion of PRAK Mitigates the Mitochondria Function and Suppresses Insulin Signaling in C2C12 Myoblasts Exposed to High Glucose.

Background: p38 regulated/activated protein kinase (PRAK) plays a crucial role in modulating cell death and survival. However, the role of PRAK in the regulation of metabolic stress remains unclear. We examined the effects of PRAK on cell survival and mitochondrial function in C2C12 myoblasts in response to high glucose stresses. Methods: PRAK of C2C12 myoblasts was knocked out by using CRISPR/Cas-9 genome editing technology. Both wild type and PRAK−/− C2C12 cells were exposed to high glucose at the concentration of 30 mmol/L to induce metabolic stress. The effect of irisin, an adipomyokine, on both wild type and PRAK−/− cells was determined to explore its relationship with RPAK. Cell viability, ATP product, glucose uptake, mitochondrial damage, and insulin signaling were assessed. Results: PRAK knockout decreased C2C12 viability in response to high glucose stress as evident by MTT assay in association with the reduction of ATP and glucose uptake. PRAK knockout enhanced apoptosis of C2C12 myoblasts in response to high glucose, consistent with an impairment in mitochondrial function, by decreasing mitochondrial membrane potential. PRAK knockout induced impairment of mitochondrial and cell damage were rescued by irisin. PRAK knockout caused decrease in phosphorylated PI3 kinase at Tyr 485, IRS-1 and AMPKα and but did not affect non-phosphorylated PI3 kinase, IRS-1 and AMPKα signaling. High glucose caused the further reduction of phosphorylated PI3 kinase, IRS-1 and AMPKα. Irisin treatment preserved phosphorylated PI3 kinase, IRS-1by rescuing PRAK in high glucose treatment. Conclusion: Our finding indicates a pivotal role of PRAK in preserving cellular survival, mitochondrial function, and high glucose stress.

EVALUATION OF DOSE-DEPENDENT ACTIVITY OF BISPHENOL F ON VIABILITY PARAMETERS AND STEROIDOGENESIS IN H295R CELLS

Increasing concern over bisphenol A (BPA) as an endocrine-disrupting chemical and recent imposition of restriction on the use of BPA paved the way for entry of its analogues in the market. Bisphenol F (BPF) is one of the major analogues of commercial value. Thus, its increasing production and application make it vulnerable to human exposure. The aim of our in vitro study was to assess the potential effect of BPF on H295R cells mitochondrial activity, metabolic activity, membrane integrity, lysosomal function, and testosterone synthesis. Adrenocortical carcinoma cells were cultivated during 24 h in the presence of BPF (0.1, 0.5, 1, 10, 25, 50, 75, 100, 300, 500 μM). Exposure doses of BPF caused a significant decrease of mitochondrial activity starting from 1 μM, we observed a slight increase in mitochondrial activity at the lowest concentration (0.1 μM). Metabolic activity decreased with increasing dose of BPF - from 10 to 500 μM. A significant increase in metabolic activity was observed after cultivation with 0.1 μM BPF and a slight increase was observed after cultivation with 0.5 μM BPF. We observed a slight increase in lysosomal function and membrane integrity after cultivation with 0.1 and 1 μM, although higher exposure doses (25 - 500 μM) caused significant decrease in membrane integrity and lysosomal function. Lowest exposure dose of BPF (0.1 μM) caused a significant increase in testosterone synthesis, on the other hand, higher exposure doses (50 - 500 μM) caused significant decrease of testosterone production. The obtained results confirmed that BPF at higher concentrations caused cytotoxicity and possibly have endocrine-disrupting potential.

Antifungal mechanism of 1-nonanol against Aspergillus flavus growth revealed by metabolomic analyses.

Chemical control of fungal spoilage of postharvest cereal grains is an important strategy for the management of grain storage. Here, the potential antifungal activity of 1-nonanol, a main component of cereal volatiles, against Aspergillus flavus was studied. The growth of A. flavus was completely inhibited by 0.11 and 0.20 μL/mL 1-nonanol at vapor and liquid contact phases, respectively. Metabolomic analysis identified 135 metabolites whose expression was significantly different between 1-nonanol-treated and untreated A. flavus. These metabolites were involved in the tricarboxylic acid cycle, amino acid biosynthesis, protein degradation and absorption, aminoacyl-tRNA biosynthesis, mineral absorption, and in interactions with ABC transporters. Biochemical validation confirmed the disruptive effect of 1-nonanol on A. flavus growth, as indicated by the leakage of intracellular electrolytes, decreased succinate dehydrogenase, mitochondrial dehydrogenase, and ATPase activity, and the accumulation of reactive oxygen species. We speculated that 1-nonanol could disrupt cell membrane integrity and mitochondrial function and might induce apoptosis of A. flavus mycelia. Simulated grain storage experiments showed that 1-nonanol vapor, at a concentration of 264 μL/L, completely inhibited A. flavus growth in wheat, corn, and paddy grain with an 18% moisture content. This study provides new insights into the antifungal mechanism of 1-nonanol against A. flavus, indicating that it has a promising potential as a bio-preservative to prevent fungal spoilage of postharvest grains. KEY POINTS: • 1-Nonanol showed higher antifungal activity against A. flavus. • The antifungal mechanisms of 1-nonanol against A. flavus were revealed. • 1-Nonanol could damage cell membrane integrity and mitochondrial function.

Cobalt Chloride Alters Mitochondrial Function in a Dose Dependent Manner

Aim: This study was carried to evaluates of Cobalt chloride (CoCl2) on cardiac mitochondrial function. Methods: H9C2 cardiomyocytes were cultured in medium containing different concentrations of CoCl2. Cell viability, cardiolipin content, mitochondrial function, and mitochondrial oxidative stress were assessed by using Cell Counting Kit-8 and suitable fluorescence kits. Results: The obtained data showed that CoCl2 (200÷400 µM) induced cell death and decreased mitochondrial function of H9C2 cardiomyocytes in dose dependence. Especially, CoCl2 at dose of 300 µM significantly altered values of mitochondrial membrane potential, H2O2 and O2- to 63.79±2.15%, 145.81±5.83% and 143.10±3.07% (of 100% control), respectively. Conclusion: CoCl2 strongly induced cardiomyocyte death via altering mitochondrial function in a dose-dependent manner.