Expression Of Mitochondrial Complex Research Articles

Unlocking Selective Anticancer Mechanisms: Dinuclear Manganese Superoxide Dismutase Mimetics Combined with Pt(II) Complexes.

We exploration the in vitro activities of the dinuclearMn2L2AcandMn2L2complexes (where HL = 2-{[di(2-pyridyl)methylamino]-methyl}phenol), possessing dual superoxide dismutase (SOD) and catalase (CAT) activity, both individually and in conjunction with various Pt(II)-complexes, either as mixtures or astheMn2-Ptadducts. Our findings revealed a notable up to 50% enhancement in the viability of healthy human breast cells, contrasted with a viability decrease as low as 50% in breast cancer cells upon combined treatments withMn2SOD mimics and Pt(II) complexes.Specifically, we synthesized and characterized the self-assembledMn2-Ptadducts(isolatedMn2L2Ptandin situMn2L2Pt'), linkingMn2L2-core with the carboxylate group ofPtDAPCl2(dichloro(2,3-diaminopropionic acid) platinum(II)). The SOD activity of the isolatedMn2L2Ptadduct (kSOD= 1.7 × 107M-1s-1) remained intact. We elucidated key mechanisms underlying the observed biological effects.We demonstrated thatMn2-containing formulations predominantly target mitochondrial processes, differently affecting the proteome of cancerous and healthy cells. They induced downregulation of H2S signaling and expression of mitochondrial complex I and III, as well as increased oxidative phosphorylation pathways and upregulation of EGFR in cancer cells. In contrast, healthy cells showed a decrease in EGFR expression and a moderate enrichment in oxidative phosphorylation pathways.

Natriuretic peptide receptor-C perturbs mitochondrial respiration in white adipose tissue

Natriuretic peptide receptor-C (NPR-C) is highly expressed in adipose tissues and regulates obesity-related diseases; however, the detailed mechanism remains unknown. In this research, we aimed to explore the potential role of NPR-C in cold exposure and high-fat/high-sugar (HF/HS) diet-induced metabolic changes, especially in regulating white adipose tissue (WAT) mitochondrial function. Our findings showed that NPR-C expression, especially in epididymal WAT (eWAT), was reduced after cold exposure. Global Npr3 (gene encoding NPR-C protein) deficiency led to reduced body weight, increased WAT browning, thermogenesis, and enhanced expression of genes related to mitochondrial biogenesis. RNA-sequencing of eWAT showed that Npr3 deficiency enhanced the expression of mitochondrial respiratory chain complex genes and promoted mitochondrial oxidative phosphorylation in response to cold exposure. In addition, Npr3 KO mice were able to resist obesity induced by HF/HS diet. Npr3 knockdown in stromal vascular fraction (SVF)-induced white adipocytes promoted the expression of proliferator-activated receptor gamma coactivator 1α (PGC1α), uncoupling protein one (UCP1), and mitochondrial respiratory chain complexes. Mechanistically, NPR-C inhibited cGMP and calcium signaling in an NPR-B-dependent manner but suppressed cAMP signaling in an NPR-B-independent manner. Moreover, Npr3 knockdown induced browning via AKT and p38 pathway activation, which were attenuated by Npr2 knockdown. Importantly, treatment with the NPR-C-specific antagonist, AP-811, decreased WAT mass and increased PGC-1α, UCP1, and mitochondrial complex expression. Our findings reveal that NPR-C deficiency enhances mitochondrial function and energy expenditure in white adipose tissue, contributing to improved metabolic health and resistance to obesity.

SIRT5 rs12216101 T>G variant is associated with liver damage and mitochondrial dysfunction in patients with non-alcoholic fatty liver disease

Sirtuin 5, encoded by the SIRT5 gene, is a NAD+-dependent deacylase that modulates mitochondrial metabolic processes through post-translational modifications. In this study, we aimed to examine the impact of the SIRT5 rs12216101T>G non-coding single nucleotide polymorphism on disease severity in patients with non-alcoholic fatty liver disease (NAFLD). The rs12216101 variant was genotyped in 2,606 consecutive European patients with biopsy-proven NAFLD. Transcriptomic analysis, expression of mitochondrial complexes and oxidative stress levels were measured in liver samples from a subset of bariatric patients. Effects of SIRT5 pharmacological inhibition were evaluated in HepG2 cells exposed to excess free fatty acids. Mitochondrial energetics invitro were investigated by high-performance liquid chromatography. In the whole cohort, the frequency distribution of SIRT5 rs12216101 TT, TG and GG genotypes was 47.0%, 42.3% and 10.7%, respectively. At multivariate logistic regression analysis adjusted for sex, age >50 years, diabetes, and PNPLA3 rs738409 status, the SIRT5 rs12216101T>G variant was associated with the presence of non-alcoholic steatohepatitis (odds ratio 1.20, 95% CI 1.03-1.40) and F2-F4 fibrosis (odds ratio 1.18; 95% CI 1.00-1.37). Transcriptomic analysis showed that the SIRT5 rs12216101T>G variant was associated with upregulation of transcripts involved in mitochondrial metabolic pathways, including the oxidative phosphorylation system. In patients carrying the G allele, western blot analysis confirmed an upregulation of oxidative phosphorylation complexes III, IV, V and consistently higher levels of reactive oxygen species, reactive nitrogen species and malondialdehyde, and lower ATP levels. Administration of a pharmacological SIRT5 inhibitor preserved mitochondrial energetic homeostasis in HepG2 cells, as evidenced by restored ATP/ADP, NAD+/NADH, NADP+/NADPH ratios and glutathione levels. The SIRT5 rs12216101T>G variant, heightening SIRT5 activity, is associated with liver damage, mitochondrial dysfunction, and oxidative stress in patients with NAFLD. In this study we discovered that the SIRT5 rs12216101T>G variant is associated with higher disease severity in patients with non-alcoholic fatty liver disease (NAFLD). This risk variant leads to a SIRT5 gain-of-function, enhancing mitochondrial oxidative phosphorylation and thus leading to oxidative stress. SIRT5 may represent a novel disease modulator in NAFLD.

Slc7a11 stimulates glutathione synthesis to preserve fatty acid metabolism in primary hepatocytes

ABSTRACTPrimary hepatocytes are widely used as a tool for studying metabolic function and regulation in the liver. However, the metabolic properties of primary hepatocytes are gradually lost after isolation. Here, we illustrated that fatty acid metabolism is the major compromised metabolic process in isolated primary hepatocytes, along with drastically decreased GSH and ROS content, while lipid peroxidation is increased. Gain- and loss-of-function studies revealed that Slc7a11 expression is critical in maintaining fatty acid metabolism and facilitating hormone-induced fatty acid metabolic events, which is synergistic with dexamethasone treatment. Intriguingly, Slc7a11 expression and dexamethasone treatment cooperatively upregulated AKT and AMPK signaling and mitochondrial complex expression in primary hepatocytes. Furthermore, direct treatment with reduced GSH or inhibition of ferroptosis is sufficient to drive protective effects on fatty acid metabolism in primary hepatocytes. Our results demonstrate that Slc7a11 expression in isolated primary hepatocytes induces GSH production, which protects against ferroptosis, to increase fatty acid metabolic gene expression, AKT and AMPK signaling and mitochondrial function in synergy with dexamethasone treatment, thereby efficiently preserving primary hepatocyte metabolic signatures, thus providing a promising approach to better reserve primary hepatocyte metabolic activities after isolation to potentially improve the understanding of liver biological functions from studies using primary hepatocytes.

Indoxyl sulfate influences susceptibility of proximal tubule epithelial cells to gentamicin cytotoxicity

Background: Patients with chronic kidney disease (CKD) are at increased risk of acute kidney injury (AKI) following exposure to nephrotoxic medications such as gentamicin, which can accelerate the progression of CKD. Therefore, there is a critical need to understand the molecular pathogenesis of acute-on-chronic kidney disease. A hallmark of CKD is the systemic bioaccumulation of uremic solutes, such as the tryptophan metabolite indoxyl sulfate (IS). Accumulating evidence suggests that IS has direct effects on the kidneys that contribute to CKD progression, and the objective of this study was to the determine the effect of IS on proximal tubule epithelial cell (PTEC) and test the hypothesis that IS exposure increases susceptibility to gentamicin-induced cytotoxicity. Methods: Cultured immortalized PTECs (HK-2 cells) were treated with IS and gentamicin at varying concentrations, and cell viability was assessed using the Trypan blue and MTT assays. TMT proteomic profiling with IBAQ quantitation and gene set enrichment analysis was used to identify differentially abundant proteins and cellular processes and pathways that are dysregulated by IS exposure and could mediate the cytotoxic effects of IS and influence susceptibility to gentamicin cytotoxicity. Results: Treatment with 100 μM IS had a modest cytotoxic effect (15-20% cell death after 24 hours over multiple experiments). Proteomic profiling of HK-2 cells identified 10,030 proteins, and IS treatment induced changes in the abundance of 60 proteins, including increased expression of kidney injury molecule-1, an established biomarker of PTEC injury, and VCAM-1, a marker of maladaptive repair after AKI. In contrast, expression of mitochondrial complex V ATPase F o subunits C1, C2, and C3 and mitochondrial ribosomal proteins L18 and L50 were down regulated, and GSEA found that there was an overall decrease in mitochondrial translation following IS exposure. These results suggest that IS is directly cytotoxic to PTECs and negatively impacts mitochondrial dynamics and cellular respiration. Pretreatment with IS increased susceptibility of HK-2 cells to 10 mM gentamicin cytotoxicity as assessed by Trypan blue staining (30.1% +/- 6.4% cells stained positive without IS pretreatment vs 46.1 +/- 3.1% with IS pretreatment, p < 0.001), and this effect was confirmed using the MTT assay. Conclusion: IS has direct cytotoxic effects on PTECs and increases their susceptibility to gentamicin cytotoxicity, and systemic bioaccumulation of IS in CKD could therefore predispose to subsequent AKI following nephrotoxic medication exposure. This phenomenon could be mediated IS-induced downregulation of mitochondrial gene translation associated with dysregulated mitochondrial dynamics and impaired cellular respiration. This study was supported by the George M. O'Brien Kidney Translational Core Center at the University of Michigan (subaward of 5P30-DK081943 14). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Arachidonic acid impairs the function of the blood-testis barrier via triggering mitochondrial complex-ROS-P38 MAPK axis in hyperthermal Sertoli cells

The death of Sertoli cells (SCs) under condition of heat stress (HS) affects spermatogenesis and is associated with impaired function of the blood-testis barrier (BTB). The fatty acid arachidonic acid (AA) is essential for the maintenance of cellular function. However, excessive release of AA during HS may adversely affect the reproductive function. The molecular mechanisms through which AA modulates the BTB in SCs are unclear. In this study, we found that 100 µM AA damaged testicular morphology and accelerated SC apoptosis during HS, reducing the stability of tight junction proteins (TJPs), shown by measurement of the levels of Claudin 11, 5, Occludin, and trans-epithelial electrical resistance (TEER). It was also found that AA adversely affected TJPs by increasing the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), activating p38 mitogen-activated protein kinases (P38 MAPK) and reducing mitochondria DNA (mtDNA) and the expression of mitochondrial complexes I and III. In contrast, pretreatment with SB203508 (a P38 MAPK inhibitor), Rotenone (an inhibitor of complex I) and Antimycin A1 (an inhibitor of complex III) reversed TJPs degradation induced by AA. Interestingly, pretreatment of cells with 10 µM Baicalein, a 12/15 lipoxygenase (12/15-LOX) -dependent inhibitor of AA production, protected against AA-induced TJPs degradation, restored mitochondrial function, and reduced apoptosis. These results suggested an intriguing link between the induction of TJPs degradation induced by AA overload and mitochondrial antioxidant function during HS, which was found to be regulated by the mitochondrial complex-ROS-P38 MAPK axis.

Abstract 14422: Mitochondrial ROS Scavenger JP4-039 Improves Mitochondrial Oxidative Phosphorylation and Induces Angiogenesis in Murine and Human Coronary Artery and Atrial Endothelial Cells

Introduction: Reducing mitochondrial ROS (mito-ROS) has been a therapeutic goal to improve cardiovascular disease. Here, we evaluated the effects of mito-ROS scavenger JP4-039 with a focus on mouse heart and human coronary artery endothelial cell (MHEC, HCAEC). Hypothesis: We hypothesized that JP4-039 would improve oxidative phosphorylation (OXPHOS) in EC and induce angiogenesis in post-AMI (acute myocardial infarction) hearts. Methods: Human atrial explants, NOX2-overexpressing (OE) MHEC, and HCAEC were treated with 1-5μM JP4-039 and examined for sprouting, tube formation, mitochondrial complex expression (Western blot), and OXPHOS measurements (Seahorse). FVB mice (n=8/group) underwent AMI surgery and were assigned to vehicle (sunflower seed oil) or JP4-039 group (1mg/kg, i.p., 3x/week for 4 weeks). Left ventricle (LV) function and capillary density in infarcted LV were assessed by echocardiogram and immunofluorescence, respectively, 28 days after AMI. Data were analyzed by One-way ANOVA and Tukey’s post-hoc, or student’s t test, as appropriate. A p-value <0.05 was considered statistically significant. Results: HCAEC treated with JP4-039 showed significantly increased expression of mitochondrial complex I (0.7±0.1 vs. 1.1±0.1) and V (1.0±0.1 vs. 1.2±0.1) with corresponding increase in basal (19.8±0.4 vs. 23.0±1.0) and maximal respiration (31.2±1.6 vs. 56.0±2.6), ATP production (16.6±0.3 vs. 18.5±0.4) and spare respiratory capacity (11.3±1.6 vs. 33.0±2.9) as compared with vehicle-treated cells. JP4-039 increased tube formation in NOX2-OE MHEC (12.6±2.2 vs. 21.3±2.4 tubes), HCAEC (33.6±3.1 vs. 49.0±2.6) as well as EC sprouting in mouse atrium (4496±1857 vs. 19552±4352 pixel 2 ). In post-AMI animals, JP4-039 improved LV systolic function (EF 24.4±3.6 vs 41.3±5.2%) and capillary density (451.7 (379.9; 629.7) vs. 698.3 (503.6; 965.8) capillaries/mm 2 ) in vivo . Conclusions: JP4-039 improved OXPHOS in ECs in vitro, and induced coronary angiogenesis in post-AMI hearts in vivo and in atrial tissues ex vivo . These findings were associated with improved cardiac function in post-AMI animals, suggesting that a mito-ROS scavenger may have significant roles in coronary angiogenesis in ischemic myocardium.

Reduced expression of mitochondrial complex I subunit Ndufs2 does not impact healthspan in mice

Aging in mammals leads to reduction in genes encoding the 45-subunit mitochondrial electron transport chain complex I. It has been hypothesized that normal aging and age-related diseases such as Parkinson’s disease are in part due to modest decrease in expression of mitochondrial complex I subunits. By contrast, diminishing expression of mitochondrial complex I genes in lower organisms increases lifespan. Furthermore, metformin, a putative complex I inhibitor, increases healthspan in mice and humans. In the present study, we investigated whether loss of one allele of Ndufs2, the catalytic subunit of mitochondrial complex I, impacts healthspan and lifespan in mice. Our results indicate that Ndufs2 hemizygous mice (Ndufs2+/−) show no overt impairment in aging-related motor function, learning, tissue histology, organismal metabolism, or sensitivity to metformin in a C57BL6/J background. Despite a significant reduction of Ndufs2 mRNA, the mice do not demonstrate a significant decrease in complex I function. However, there are detectable transcriptomic changes in individual cell types and tissues due to loss of one allele of Ndufs2. Our data indicate that a 50% decline in mRNA of the core mitochondrial complex I subunit Ndufs2 is neither beneficial nor detrimental to healthspan.

Lower citrate synthase activity, mitochondrial complex expression, and fewer oxidative myofibers characterize skeletal muscle from growth-restricted fetal sheep.

Skeletal muscle from the late gestation sheep fetus with intrauterine growth restriction (IUGR) has evidence of reduced oxidative metabolism. Using a sheep model of placental insufficiency and IUGR, we tested the hypothesis that by late gestation, IUGR fetal skeletal muscle has reduced capacity for oxidative phosphorylation because of intrinsic deficits in mitochondrial respiration. We measured mitochondrial respiration in permeabilized muscle fibers from biceps femoris (BF) and soleus (SOL) from control and IUGR fetal sheep. Using muscles including BF, SOL, tibialis anterior (TA), and flexor digitorum superficialis (FDS), we measured citrate synthase (CS) activity, mitochondrial complex subunit abundance, fiber type distribution, and gene expression of regulators of mitochondrial biosynthesis. Ex vivo mitochondrial respiration was similar in control and IUGR muscle. However, CS activity was lower in IUGR BF and TA, indicating lower mitochondrial content, and protein expression of individual mitochondrial complex subunits was lower in IUGR TA and BF in a muscle-specific pattern. IUGR TA, BF, and FDS also had lower expression of type I oxidative fibers. Fiber-type shifts that support glycolytic instead of oxidative metabolism may be advantageous for the IUGR fetus in a hypoxic and nutrient-deficient environment, whereas these adaptions may be maladaptive in postnatal life.

Quercitrin Attenuates Acetaminophen-Induced Acute Liver Injury by Maintaining Mitochondrial Complex I Activity.

The flavonoid quercitrin has a strong antioxidant property. It is also reported to have a protective effect on the liver. However, the mechanism by which it exerts a protective effect on the liver is not fully understood. The objective of this article is to confirm the protective effect of quercitrin extracted from Albiziae flos on acetaminophen (APAP)-induced liver injury and to explain its mechanism. In the in vivo study, quercitrin was administered orally to BALB/c mice at a dose of 50, 100, and 200 mg/kg for seven consecutive days. APAP (300 mg/kg) was injected intraperitoneally after a last dose of quercitrin was administered. Determination of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GSH-Px), catalase (CAT), and malondialdehyde (MDA) levels showed that quercitrin effectively attenuated APAP-induced acute liver injury in mice. Results of the in vitro study showed that quercitrin reduced the levels of ROS, protected mitochondria from damage, and restored the activity of mitochondrial complex I in APAP-treated L-02 cells. The addition of rotenone which is an inhibitor of complex I blocked the protective effect of quercitrin. The expression of mitochondrial complex I was also maintained by quercitrin. Our results suggest that quercitrin can maintain the level of mitochondrial complex I in injured cells and restore its activity, which reduces the production of ROS, protects the mitochondria from oxidative stress, and has a protective effect on the liver.

Maternal Roux-en-Y gastric bypass surgery reduces lipid deposition and increases UCP1 expression in the brown adipose tissue of male offspring

Maternal obesity induced by cafeteria diet (CAF) predisposes offspring to obesity and metabolic diseases, events that could be avoided by maternal bariatric surgery (BS). Herein we evaluated whether maternal BS is able to modulate brown adipose tissue (BAT) morphology and function in adult male rats born from obese female rats submitted to Roux-en-Y gastric bypass (RYGB). For this, adult male rat offspring were obtained from female rats that consumed standard diet (CTL), or CAF diet, and were submitted to simulated operation or RYGB. Analysis of offspring showed that, at 120 days of life, the maternal CAF diet induced adiposity and decreased the expression of mitochondrial Complex I (CI) and Complex III (CIII) in the BAT, resulting in higher accumulation of lipids than in BAT from offspring of CTL dams. Moreover, maternal RYGB increased UCP1 expression and prevented excessive deposition of lipids in the BAT of adult male offspring rats. However, maternal RYGB failed to reverse the effects of maternal diet on CI and CIII expression. Thus, maternal CAF promotes higher lipid deposition in the BAT of offspring, contributing to elevated adiposity. Maternal RYGB prevented obesity in offspring, probably by increasing the expression of UCP1.

Heterochronic Parabiosis: Old Blood Induces Changes in Mitochondrial Structure and Function of Young Mice.

Heterochronic parabiosis models have been utilized to demonstrate the role of blood-borne circulating factors in systemic effects of aging. In previous studies, heterochronic parabiosis has shown positive effects across multiple tissues in old mice. More recently, a study demonstrated old blood had a more profound negative effect on muscle performance and neurogenesis of young mice. In this study, we used heterochronic parabiosis to test the hypothesis that circulating factors mediate mitochondrial bioenergetic decline, a well-established biological hallmark of aging. We examined mitochondrial morphology, expression of mitochondrial complexes, and mitochondrial respiration from skeletal muscle of mice connected as heterochronic pairs, as well as young and old isochronic controls. Our results indicate that young heterochronic mice had significantly lower total mitochondrial content and on average had significantly smaller mitochondria compared to young isochronic controls. Expression of complex IV followed a similar pattern: young heterochronic mice had a trend for lower expression compared to young isochronic controls. Additionally, respirometric analyses indicate that young heterochronic mice had significantly lower complex I, complex I + II, and maximal mitochondrial respiration and a trend for lower complex II-driven respiration compared to young isochronic controls. Interestingly, we did not observe significant improvements in old heterochronic mice compared to old isochronic controls, demonstrating the profound deleterious effects of circulating factors from old mice on mitochondrial structure and function. We also found no significant differences between the young and old heterochronic mice, demonstrating that circulating factors can be a driver of age-related differences in mitochondrial structure and function.

Haploinsufficiency of Transferrin Receptor 1 Impairs Angiogenesis with Reduced Mitochondrial Complex I in Mice with Limb Ischemia

Limb ischemia (LI) is a major consequence of peripheral artery disease (PAD) with a high mortality rate. Iron is an essential mineral to maintain physiological function of multiple organs. Intracellular iron transport is regulated by transferrin receptor 1 (TfR1). Although increase in serum ferritin levels has been reported in PAD patients, the mechanism of iron metabolism in LI is still unclear. The aim of this study is to investigate whether TfR1 deletion attenuates LI formation. To generate LI, the left femoral artery of 8–10 week-old C57BL6/J male mice was ligated. Adductor muscles were harvested at 28 days after surgery to investigate iron metabolism. The level of ferritin, intracellular iron storage protein, was higher in ischemic adductor muscles compared to non-ischemic adductor muscles. Level of intracellular iron transport protein, TfR1, was decreased in ischemic adductor muscles. LI was then generated in TfR1 heterozygous deleted mice (TfR1+/−) to examine whether TfR1 contributes to the pathophysiology of LI. Laser Doppler blood flowmetry revealed that blood flow recovery was attenuated in TfR1+/− mice compared to wild type (WT) littermates, along with decreased expression of ferritin and CD31 in ischemic adductor muscles. Since iron is used for energy production in mitochondria, we then assessed mitochondrial complexes in the ischemic adductor muscle. Of interest, expression of mitochondrial complex I, but not complexes II, III, and V in ischemic adductor muscles was significantly reduced in TfR1+/− mice compared to WT mice. Haploinsufficiency of TfR1 attenuated angiogenesis via reduction of mitochondrial complex I in LI in mice.

Mitochondrial ROS and NLRP3 inflammasome in acute ozone-induced murine model of airway inflammation and bronchial hyperresponsiveness

Oxidative stress is a key mechanism underlying ozone-induced lung injury. Mitochondria can release mitochondrial reactive oxidative species (mtROS), which may lead to the activation of NLRP3 inflammasome. The goal of this study was to examine the roles of mtROS and NLRP3 inflammasome in acute ozone-induced airway inflammation and bronchial hyperresponsiveness (BHR). C57/BL6 mice (n = 8/group) were intraperitoneally treated with vehicle (phosphate buffered saline, PBS) or mitoTEMPO (mtROS inhibitor, 20 mg/kg), or orally treated with VX-765 (caspse-1 inhibitor, 100 mg/kg) 1 h before the ozone exposure (2.5 ppm, 3 h). Compared to the PBS-treated ozone-exposed mice, mitoTEMPO reduced the level of total malondialdehyde in bronchoalveolar lavage (BAL) fluid and increased the expression of mitochondrial complexes II and IV in the lung 24 h after single ozone exposure. VX-765 inhibited ozone-induced BHR, BAL total cells including neutrophils and eosinophils, and BAL inflammatory cytokines including IL-1α, IL-1β, KC, and IL-6. Both mitoTEMPO and VX-765 reduced ozone-induced mtROS and inhibited capase-1 activity in lung tissue whilst VX-765 further inhibited DRP1 and MFF expression, increased MFN2 expression, and down-regulated caspase-1 expression in the lung tissue. These results indicate that acute ozone exposure induces mitochondrial dysfunction and NLRP3 inflammasome activation, while the latter has a critical role in the pathogenesis of ozone-induced airway inflammation and BHR.

Berberine ameliorates fatty acid-induced oxidative stress in human hepatoma cells

Oxidative stress is thought to be critical for the pathogenesis of hepatic steatosis and its progress to non-alcoholic steatohepatitis. Berberine (BBR) can improve hepatic steatosis. In this study, we investigated the role of BBR in ameliorating oxidative stress. Lipid accumulation was measured in the livers of C57BL/6 mice fed a high fat diet (HFD) or a normal diet for 8 weeks, then either received BBR or vehicle for the study duration. Nrf2 distribution was detected in male Sprague-Dawley rats’ livers in vivo and in Huh7 cells in vitro. ROS generation and mitochondrial complex expression was measured in Huh7 cells. HepG2 cells were employed for the measurement of oxygen consumption rates. Our results showed that BBR reduced triglyceride accumulation in the liver of HFD-fed mice. The activation and nuclear distribution of Nrf2 was decreased in the hepatocytes of rats that received BBR treatment, while on a HFD. BBR also markedly reduced Nox2-dependent cytoplasmic ROS production and mitochondrial ROS production, which was mediated by the down-regulation of Complex I and III expression. In conclusion, BBR has a great potential to reduce the effects of oxidative stress, which likely contributes to its protective effect in inhibiting the progression of hepatic steatosis to steatohepatitis.

AMC-Bio-Artificial Liver culturing enhances mitochondrial biogenesis in human liver cell lines: The role of oxygen, medium perfusion and 3D configuration

BackgroundHuman liver cell lines, like HepaRG and C3A, acquire higher functionality when cultured in the AMC-Bio-Artificial Liver (AMC-BAL). The three main differences between BAL and monolayer culture are the oxygenation (40% vs 20%O2), dynamic vs absent medium perfusion and 3D vs 2D configuration. Here, we investigated the background of the differences between BAL-cultures and monolayers. MethodsWe performed whole-genome microarray analysis on HepaRG monolayer and BAL-cultures. Next, mitochondrial biogenesis was studied in monolayer and BAL-cultures of HepaRG and C3A. The driving forces for mitochondrial biogenesis by BAL-culturing were investigated in representative culture models differing in oxygenation level, medium flow or 2D vs 3D configuration. ResultsGene-sets related to mitochondrial energy metabolism were most prominently up-regulated in HepaRG-BAL vs monolayer cultures. This was confirmed by a 2.4-fold higher mitochondrial abundance with increased expression of mitochondrial OxPhos complexes. Moreover, the transcript levels of mitochondria-encoded genes were up to 3.6-fold induced and mitochondrial membrane potential activity was 8.3-fold increased in BAL vs monolayers. Culturing with 40% O2, dynamic medium flow and/or in 3D increased the mitochondrial abundance and expression of mitochondrial complexes vs standard monolayer culturing. The stimulatory effect of the BAL culture on mitochondrial biogenesis was confirmed in C3A cells in which mitochondrial abundance increased 2.2-fold with induction of mitochondria-encoded genes. Conclusions and general significanceThe increased functionality of liver cell lines upon AMC-BAL culturing is associated with increased mitochondrial biogenesis. High oxygenation, medium perfusion and 3D configuration contribute to the up-regulation of the mitochondrial biogenesis.

Sesamol Induces Human Hepatocellular Carcinoma Cells Apoptosis by Impairing Mitochondrial Function and Suppressing Autophagy

Sesamol, a nutritional phenolic antioxidant compound enriched in sesame seeds, has been shown to have potential anticancer activities. This study aims at characterizing the antitumor efficacy of sesamol and unveiling the importance of mitochondria in sesamol-induced effects using a human hepatocellular carcinoma cell line, HepG2 cells. Results of this study showed that sesamol treatment suppressed colony formation, elicited S phase arrest during cell cycle progression, and induced both intrinsic and extrinsic apoptotic pathway in vitro with a dose-dependent manner. Furthermore, sesamol treatment elicited mitochondrial dysfunction by inducing a loss of mitochondrial membrane potential. Impaired mitochondria and accumulated H2O2 production resulted in disturbance of redox-sensitive signaling including Akt and MAPKs pathways. Mitochondrial biogenesis was inhibited as suggested by the decline in expression of mitochondrial complex I subunit ND1, and the upstream AMPK/PGC1α signals. Importantly, sesamol inhibited mitophagy and autophagy through impeding the PI3K Class III/Belin-1 pathway. Autophagy stimulator rapamycin reversed sesamol-induced apoptosis and mitochondrial respiration disorders. Moreover, it was also shown that sesamol has potent anti-hepatoma activity in a xenograft nude mice model. These data suggest that mitochondria play an essential role in sesamol-induced HepG2 cells death, and further research targeting mitochondria will provide more chemotherapeutic opportunities.

Abstract 5168: Mitochondrial 16srRNA variants and complex III expression in serous ovarian cancer

Abstract Patients suffering from serous ovarian cancer (SOC) are typically diagnosed at later stage, drastically decreasing their five-year survival prospect. Diagnostic tools, including the measurement of elevated levels of the CA125 protein released by ovarian tumors, provide valuable information but are inherently limited in specificity in diverse populations. Hence, there remains a need for more advanced diagnostic tests to distinguish the different histopathological subclasses to improve treatment outcome. Reactive oxygen species (ROS), by products of normal energy production within the mitochondria, are among the list of compounds believed to be involved in aging and the pathogenesis of many human diseases. Moreover, elevated ROS levels may cause subtle changes in regions of the mitochondrial genome (mtDNA) inducing oxidative stress and tumor microenvironment. Consequently, the events could be used to establish potential mtDNA markers involved in the progression of SOC as an age related disease. The aim of this study is to determine mitochondrial mutational roles and protein expression level in both precancerous and malignant stages of SOC. In the current study PCR-based sequencing was used to detect mtDNA sequence variants in the 16srRNA gene, known to be highly mutated in SOC. The gene spans 1671 to 3229 bp within the mtDNA and is highly conserved. Thirty-one frozen SOC tissue samples of four histopathological subclasses [cystadenoma, n = 7; borderline, n = 8; and malignant stages III/IV, n = 8 and normal no egg, no surface epithelium as a control, n = 8] were examined. Additionally, expression of mitochondrial complex III (Coenzyme Q-cytochrome c reductase) was evaluated using western blot analysis. Forty variants were detected of which three were unreported. G1811A, an unreported variant was detected in 50% of the borderline samples. The unreported variant C2794G was detected in normal, cystadenoma, and borderline with an increasing frequency of 50%, 83% and 100% correspondingly, however did not display in the malignant samples. A3364G an unreported variant was observed in all four categories with a frequency of approximately 70% or higher. Complex III was expressed progressively in normal, borderline and malignant samples. Moreover, the expression of complex III was significantly higher in the malignant samples compared to the normal control. Results from this study could suggest that the genetic instability of 16srRNA region may play a role in ovarian tumorigenicity. Additionally the over expression of complex III in the malignant stages could serve as a target for chemotherapy of serous ovarian disease. Citation Format: Shakeria L. Cohen, Sharifeh Mehrabi, Edward E. Partridge, Felix Aikhionbare. Mitochondrial 16srRNA variants and complex III expression in serous ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5168.

Differential Mitochondrial Adaptation in Primary Vascular Smooth Muscle Cells from a Diabetic Rat Model.

Diabetes affects more than 330 million people worldwide and causes elevated cardiovascular disease risk. Mitochondria are critical for vascular function, generate cellular reactive oxygen species (ROS), and are perturbed by diabetes, representing a novel target for therapeutics. We hypothesized that adaptive mitochondrial plasticity in response to nutrient stress would be impaired in diabetes cellular physiology via a nitric oxide synthase- (NOS-) mediated decrease in mitochondrial function. Primary smooth muscle cells (SMCs) from aorta of the nonobese, insulin resistant rat diabetes model Goto-Kakizaki (GK) and the Wistar control rat were exposed to high glucose (25 mM). At baseline, significantly greater nitric oxide evolution, ROS production, and respiratory control ratio (RCR) were observed in GK SMCs. Upon exposure to high glucose, expression of phosphorylated eNOS, uncoupled respiration, and expression of mitochondrial complexes I, II, III, and V were significantly decreased in GK SMCs (p < 0.05). Mitochondrial superoxide increased with high glucose in Wistar SMCs (p < 0.05) with no change in the GK beyond elevated baseline concentrations. Baseline comparisons show persistent metabolic perturbations in a diabetes phenotype. Overall, nutrient stress in GK SMCs caused a persistent decline in eNOS and mitochondrial function and disrupted mitochondrial plasticity, illustrating eNOS and mitochondria as potential therapeutic targets.

The role of microRNA miR223 in immune adaptation for pregnancy and fetal-placental development

The role of microRNA miR223 in immune adaptation for pregnancy and fetal-placental development