Thioredoxin1 Upregulates Mitochondrial Proteins Related to Oxidative Phosphorylation and TCA Cycle in the Heart

AbstractProximal tubular epithelial cells (TECs) demand high energy and rely on mitochondrial oxidative phosphorylation as the main energy source. However, this is disturbed in renal fibrosis. Acetylation is an important post-translational modification for mitochondrial metabolism. The mitochondrial protein NAD+-dependent deacetylase sirtuin 3 (SIRT3) regulates mitochondrial metabolic function. Therefore, we aimed to identify the changes in the acetylome in tubules from fibrotic kidneys and determine their association with mitochondria. We found that decreased SIRT3 expression was accompanied by increased acetylation in mitochondria that have separated from TECs during the early phase of renal fibrosis. Sirt3 knockout mice were susceptible to hyper-acetylated mitochondrial proteins and to severe renal fibrosis. The activation of SIRT3 by honokiol ameliorated acetylation and prevented renal fibrosis. Analysis of the acetylome in separated tubules using LC–MS/MS showed that most kidney proteins were hyper-acetylated after unilateral ureteral obstruction. The increased acetylated proteins with 26.76% were mitochondrial proteins which were mapped to a broad range of mitochondrial pathways including fatty acid β-oxidation, the tricarboxylic acid cycle (TCA cycle), and oxidative phosphorylation. Pyruvate dehydrogenase E1α (PDHE1α), which is the primary link between glycolysis and the TCA cycle, was hyper-acetylated at lysine 385 in TECs after TGF-β1 stimulation and was regulated by SIRT3. Our findings showed that mitochondrial proteins involved in regulating energy metabolism were acetylated and targeted by SIRT3 in TECs. The deacetylation of PDHE1α by SIRT3 at lysine 385 plays a key role in metabolic reprogramming associated with renal fibrosis.

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Lactate oxidative phosphorylation by annulus fibrosus cells: evidence for lactate-dependent metabolic symbiosis in intervertebral discs

Arthritis Research & Therapy ◽

10.1186/s13075-021-02501-2 ◽

2021 ◽

Vol 23 (1) ◽

Author(s):

Dong Wang ◽

Robert Hartman ◽

Chao Han ◽

Chao-ming Zhou ◽

Brandon Couch ◽

...

Keyword(s):

Amino Acids ◽

Lactic Acid ◽

Oxidative Phosphorylation ◽

Intervertebral Disc ◽

Annulus Fibrosus ◽

Tca Cycle ◽

Heavy Isotope ◽

In Vivo Models ◽

Disc Tissue ◽

Tca Cycle Intermediates

Abstract Background Intervertebral disc degeneration contributes to low back pain. The avascular intervertebral disc consists of a central hypoxic nucleus pulpous (NP) surrounded by the more oxygenated annulus fibrosus (AF). Lactic acid, an abundant end-product of NP glycolysis, has long been viewed as a harmful waste that acidifies disc tissue and decreases cell viability and function. As lactic acid is readily converted into lactate in disc tissue, the objective of this study was to determine whether lactate could be used by AF cells as a carbon source rather than being removed from disc tissue as a waste byproduct. Methods Import and conversion of lactate to tricarboxylic acid (TCA) cycle intermediates and amino acids in rabbit AF cells were measured by heavy-isotope (13C-lactate) tracing experiments using mass spectrometry. Levels of protein expression of lactate converting enzymes, lactate importer and exporter in NP and AF tissues were quantified by Western blots. Effects of lactate on proteoglycan (35S-sulfate) and collagen (3H-proline) matrix protein synthesis and oxidative phosphorylation (Seahorse XFe96 Extracellular Flux Analyzer) in AF cells were assessed. Results Heavy-isotope tracing experiments revealed that AF cells imported and converted lactate into TCA cycle intermediates and amino acids using in vitro cell culture and in vivo models. Addition of exogenous lactate (4 mM) in culture media induced expression of the lactate importer MCT1 and increased oxygen consumption rate by 50%, mitochondrial ATP-linked respiration by 30%, and collagen synthesis by 50% in AF cell cultures grown under physiologic oxygen (2-5% O2) and glucose concentration (1-5 mM). AF tissue highly expresses MCT1, LDH-H, an enzyme that preferentially converts lactate to pyruvate, and PDH, an enzyme that converts pyruvate to acetyl-coA. In contrast, NP tissue highly expresses MCT4, a lactate exporter, and LDH-M, an enzyme that preferentially converts pyruvate to lactate. Conclusions These findings support disc lactate-dependent metabolic symbiosis in which lactate produced by the hypoxic, glycolytic NP cells is utilized by the more oxygenated AF cells via oxidative phosphorylation for energy and matrix production, thus shifting the current research paradigm of viewing disc lactate as a waste product to considering it as an important biofuel. These scientifically impactful results suggest novel therapeutic targets in disc metabolism and degeneration.

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Training-induced adaptation of oxidative phosphorylation in skeletal muscles

Biochemical Journal ◽

10.1042/bj20030526 ◽

2003 ◽

Vol 374 (1) ◽

pp. 37-40 ◽

Cited By ~ 34

Author(s):

Bernard KORZENIEWSKI ◽

Jerzy A. ZOLADZ

Keyword(s):

Quantitative Analysis ◽

Oxidative Phosphorylation ◽

Skeletal Muscles ◽

Oxygen Uptake Kinetics ◽

Mitochondrial Proteins ◽

Muscle Training ◽

Direct Stimulation ◽

Atp Supply ◽

Parallel Activation ◽

Stimulation Of

Muscle training/conditioning improves the adaptation of oxidative phosphorylation in skeletal muscles to physical exercise. However, the mechanisms underlying this adaptation are still not understood fully. By quantitative analysis of the existing experimental results, we show that training-induced acceleration of oxygen-uptake kinetics at the onset of exercise and improvement of ATP/ADP stability due to physical training are mainly caused by an increase in the amount of mitochondrial proteins and by an intensification of the parallel activation of ATP usage and ATP supply (increase in direct stimulation of oxidative phosphorylation complexes accompanying stimulation of ATP consumption) during exercise.

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DNA methylation and transcriptomic alterations define distinct groups in pediatric spinal ependymoma

Neuro-Oncology ◽

10.1093/neuonc/noz167.025 ◽

2019 ◽

Vol 21 (Supplement_4) ◽

pp. iv6-iv6

Author(s):

Omar Ahmad ◽

Rebecca Chapman ◽

Lisa Storer ◽

Li Luo ◽

Linda Resar ◽

...

Keyword(s):

Dna Methylation ◽

Oxidative Phosphorylation ◽

Copy Number ◽

Transcriptome Profiling ◽

Tca Cycle ◽

Methylation Data ◽

Spinal Ependymoma ◽

Astrocyte Differentiation ◽

Dna Copy Number Alterations ◽

Age Range

Abstract In contrast, compared to adults, spinal ependymomas (SEPN) are less common in childhood and adolescents. Children with these tumours are likely to experience a more aggressive disease course, with a higher rate of local failure, and a higher rate of metastasis. Presently the molecular basis of SEPN is poorly characterized. Therefore, we have analyzed 29 SEPN tumour samples from pediatric patients (female: 11, male: 15; age range: 4 – 21 years) and performed DNA methylation (n=28) and transcriptome profiling (n=29). Unsupervised analysis of methylation data reliably separated these tumours into two distinct groups: one group covering all myxopapillary ependymomas (MPE) and a second group dominated by grade II SPENs (SP-EPN). We identified 242 differentially methylated regions between these two groups, of which 56% showed high methylation levels in MPE, including 22 regions localized on chromosome 6. Genome-wide copy number analysis using methylation data showed differences in numbers and pattern of DNA copy number alterations between these groups. Gain of chromosome 20 (39%) followed by loss of chromosomes 6 (28%), 10 (28%), and 13 (28%) were detected in the MPE group, whereas loss of chromosome 22 was frequent (60%) in the SP-EPN group. Transcriptomic analysis showed that genes associated with oxidative phosphorylation, TCA cycle components, electron transport, and Interferon-gamma production characterize the MPE group whereas potassium ion import and regulation of astrocyte differentiation characterize the SP-EPN group. Taken together, this data suggest that mitochondrial oxidative phosphorylation may drive the regulation of energy metabolism of MPE tumours.

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Mitochondrial Complex I Function Affects Halothane Sensitivity in Caenorhabditis elegans

Anesthesiology ◽

10.1097/00000542-200408000-00017 ◽

2004 ◽

Vol 101 (2) ◽

pp. 365-372 ◽

Cited By ~ 24

Author(s):

Ernst-Bernhard Kayser ◽

Phil G. Morgan ◽

Margaret M. Sedensky

Keyword(s):

Caenorhabditis Elegans ◽

Oxidative Phosphorylation ◽

Oxidative Damage ◽

Adenosine Triphosphate ◽

Complex I ◽

Volatile Anesthetics ◽

Mitochondrial Proteins ◽

Wild Type ◽

Complex Ii ◽

C Elegans

Background : The gene gas-1 encodes a subunit of complex I of the mitochondrial electron transport chain in Caenorhabditis elegans. A mutation in gas-1 profoundly increases sensitivity of C. elegans to volatile anesthetics. It is unclear which aspects of mitochondrial function account for the hypersensitivity of the mutant. Methods : Oxidative phosphorylation was determined by measuring mitochondrial oxygen consumption using electron donors specific for either complex I or complex II. Adenosine triphosphate concentrations were determined by measuring luciferase activity. Oxidative damage to mitochondrial proteins was identified using specific antibodies. Results : Halothane inhibited oxidative phosphorylation in isolated wild-type mitochondria within a concentration range that immobilizes intact worms. At equal halothane concentrations, complex I activity but not complex II activity was lower in mitochondria from mutant (gas-1) animals than from wild-type (N2) animals. The halothane concentrations needed to immobilize 50% of N2 or gas-1 animals, respectively, did not reduce oxidative phosphorylation to identical rates in the two strains. In air, adenosine triphosphate concentrations were similar for N2 and gas-1 but were decreased in the presence of halothane only in gas-1 animals. Oxygen tension changed the sensitivity of both strains to halothane. When nematodes were raised in room air, oxidative damage to mitochondrial proteins was increased in the mutant animal compared with the wild type. Conclusions : Rates of oxidative phosphorylation and changes in adenosine triphosphate concentrations by themselves do not control anesthetic-induced immobility of wild-type C. elegans. However, they may contribute to the increased sensitivity to volatile anesthetics of the gas-1 mutant. Oxidative damage to proteins may be an important contributor to sensitivity to volatile anesthetics in C. elegans.

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Dynamics of Energy Metabolism in Carbon Starvation-Induced Fruitlet Abscission in Litchi

Horticulturae ◽

10.3390/horticulturae7120576 ◽

2021 ◽

Vol 7 (12) ◽

pp. 576

Author(s):

Qian Wu ◽

Xingshuai Ma ◽

Qingxin Chen ◽

Ye Yuan ◽

Huicong Wang ◽

...

Keyword(s):

Energy Metabolism ◽

Oxidative Phosphorylation ◽

Citrate Synthase ◽

Tca Cycle ◽

Carbon Starvation ◽

Fruit Abscission ◽

Oxidative Phosphorylation Pathway ◽

Glycolysis Pathway ◽

Liquid Chromatography Tandem Mass ◽

Fruitlet Abscission

Fruit abscission is triggered by multiple changes in endogenous components of the fruit, including energy metabolism. However, it is still unknown how the core energy metabolism pathways are modified during fruit abscission. Here, we investigated the relationship between carbon starvation-induced fruitlet abscission and energy metabolism changes in litchi. The fruitlet abscission of litchi ‘Feizixiao’ was induced sharply by girdling plus defoliation (GPD), a carbon stress treatment. Using liquid chromatography tandem mass spectrometry (LC-MS/MS) targeted metabolomics analysis, we identified a total of 21 metabolites involved in glycolysis, TCA cycle and oxidative phosphorylation pathways. Among them, the content of most metabolites in glycolysis pathways and TCA cycles was reduced, and the activity of corresponding metabolic enzymes such as ATP-dependent phosphofructokinase (ATP-PFK), pyruvate kinase (PK), citrate synthase (CS), succinate thiokinase (SAT), and NAD-dependent malate dehydrogenase (NAD-MDH) was decreased. Consistently, we further showed that the expression of the relative genes (LcPFK2, LcPK2, LcPK4, LcCS1, LcCS2, LcSAT, LcMDH1 and LcMDH2) was also significantly down-regulated. In contrast, the level of ATP, an important metabolite in the oxidative phosphorylation pathway, was elevated in parallel with both higher activity of H+-ATPase and the increased expression level of LcH+-ATPase1. In conclusion, our findings suggest that carbon starvation can induce fruitlet abscission in litchi probably by energy depletion that mediated through both the suppression of the glycolysis pathway and TCA cycle and the enhancement of the oxidative phosphorylation pathway.

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Succinate Supplement Elicited “Pseudohypoxia” Condition to Promote Proliferation, Migration, and Osteogenesis of Periodontal Ligament Cells

Stem Cells International ◽

10.1155/2020/2016809 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Huimin Mao ◽

Andi Yang ◽

Yunhe Zhao ◽

Lang Lei ◽

Houxuan Li

Keyword(s):

Stem Cells ◽

Mesenchymal Stem Cells ◽

Oxidative Phosphorylation ◽

Periodontal Ligament ◽

Cell Metabolism ◽

Tca Cycle ◽

Metabolic Reprogramming ◽

Periodontal Ligament Cells ◽

Low Oxygen

Most mesenchymal stem cells reside in a niche of low oxygen tension. Iron-chelating agents such as CoCl2 and deferoxamine have been utilized to mimic hypoxia and promote cell growth. The purpose of the present study was to explore whether a supplement of succinate, a natural metabolite of the tricarboxylic acid (TCA) cycle, can mimic hypoxia condition to promote human periodontal ligament cells (hPDLCs). Culturing hPDLCs in hypoxia condition promoted cell proliferation, migration, and osteogenic differentiation; moreover, hypoxia shifted cell metabolism from oxidative phosphorylation to glycolysis with accumulation of succinate in the cytosol and its release into culture supernatants. The succinate supplement enhanced hPDLC proliferation, migration, and osteogenesis with decreased succinate dehydrogenase (SDH) expression and activity, as well as increased hexokinase 2 (HK2) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), suggesting metabolic reprogramming from oxidative phosphorylation to glycolysis in a normal oxygen condition. The succinate supplement in cell cultures promoted intracellular succinate accumulation while stabilizing hypoxia inducible factor-1α (HIF-1α), leading to a state of pseudohypoxia. Moreover, we demonstrate that hypoxia-induced proliferation was G-protein-coupled receptor 91- (GPR91-) dependent, while exogenous succinate-elicited proliferation involved the GPR91-dependent and GPR91-independent pathway. In conclusion, the succinate supplement altered cell metabolism in hPDLCs, induced a pseudohypoxia condition, and enhanced proliferation, migration, and osteogenesis of mesenchymal stem cells in vitro.

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Deoxynivalenol Affects Cell Metabolism and Increases Protein Biosynthesis in Intestinal Porcine Epithelial Cells (IPEC-J2): DON Increases Protein Biosynthesis

Toxins ◽

10.3390/toxins10110464 ◽

2018 ◽

Vol 10 (11) ◽

pp. 464 ◽

Cited By ~ 4

Author(s):

Constanze Nossol ◽

Peter Landgraf ◽

Stefan Kahlert ◽

Michael Oster ◽

Berend Isermann ◽

...

Keyword(s):

Oxidative Phosphorylation ◽

De Novo ◽

Protein Biosynthesis ◽

Lactate Production ◽

Glucose Consumption ◽

Tca Cycle ◽

Economic Losses ◽

Anaerobic Glycolysis ◽

Low Glucose ◽

The Impact

Deoxynivalenol (DON) is a toxin found in cereals as well as in processed products such as pasta, and causes substantial economic losses for stock breeding as it induces vomiting, reduced feeding, and reduced growth rates in piglets. Oxidative phosphorylation, TCA-cycle, transcription, and translation have been hypothesized to be leading pathways that are affected by DON. We used an application of high and low glucose to examine oxidative phosphorylation and anaerobic glycolysis. A change in the metabolic status of IPEC-J2 was observed and confirmed by microarray data. Measurements of oxygen consumption resulted in a significant reduction, if DON attacks from the basolateral. Furthermore, we found a dose-dependent effect with a significant reduction at 2000 ng/mL. In addition, SLC7A11 and PHB, the genes with the highest regulation in our microarray analyses under low glucose supply, were investigated and showed a variable regulation on protein level. Lactate production and glucose consumption was investigated to examine the impact of DON on anaerobic glycolysis and we observed a significant increase in 2000 blhigh and a decrease in 2000 aphigh. Interestingly, both groups as well as 200 blhigh showed a significant higher de novo protein synthesis when compared to the control. These results indicate the direct or indirect impact of DON on metabolic pathways in IPEC-J2.

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Translational inhibitors as potential therapeutic tool of human neuroblastoma through mitochondrial gene expression

European Psychiatry ◽

10.1016/j.eurpsy.2017.01.517 ◽

2017 ◽

Vol 41 (S1) ◽

pp. S464-S464

Author(s):

S. Hina

Keyword(s):

Gene Expression ◽

Oxidative Phosphorylation ◽

Neuroendocrine Tumour ◽

Mitochondrial Gene ◽

Mitochondrial Protein ◽

Genetic Material ◽

Neuronal Cell ◽

Mitochondrial Proteins ◽

Mitochondrial Gene Expression ◽

Human Neuroblastoma

Neuroblastoma is a solid neuroendocrine tumour and most common type of cancer of infancy. It is a complex heterogeneous disease and many factors such as molecular, cellular and genetic features are involved in its development. Mitochondria play a pivotal role in neuronal cell survival or death. Neurons are highly reliant on aerobic oxidative phosphorylation (OXPHOS) for their energy needs. Defective activities of mitochondrial complexes I, II, III and IV have been identified in many neurological and neurodegenerative diseases. Human mitochondria with its own genetic material meet the needs required for the assembly of subunits of the oxidative phosphorylation (OXPHOS) complexes. A number of translational inhibitors are known that could potentially effect translation of mitochondrial protein synthesis. Among these puromycin, homoharringtonine and cyclohexamide were selected for the present study. The effect of these translational inhibitors on mitochondrial gene expression for the treatment of neuroblastoma are not well established. Therefore, in this study, we have investigated the effects of these translational inhibitors on the expression of human mitochondrial gene expression in SH-SY5Y neuroblastoma cells.We observed a significant effect on the level of mitochondrial transcripts upon exposure to these translation inhibitors in SH-SY5Y cells, however, the effects on expression of mitochondrial proteins were minimal. This suggests that translational inhibitors might not directly affect the abundance of mitochondrial proteins. Translational inhibitors induce significant effect on mitochondrial gene expression that can be lead to the new-targeted therapy for treating neuroblastoma.

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Metabolic stress is a barrier to Epstein–Barr virus-mediated B-cell immortalization

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1517141113 ◽

2016 ◽

Vol 113 (6) ◽

pp. E782-E790 ◽

Cited By ~ 52

Author(s):

Karyn McFadden ◽

Amy Y. Hafez ◽

Rigel Kishton ◽

Joshua E. Messinger ◽

Pavel A. Nikitin ◽

...

Keyword(s):

Oxidative Phosphorylation ◽

Epstein Barr Virus ◽

Growth Arrest ◽

Metabolic Stress ◽

Tca Cycle ◽

Barr Virus ◽

The Tca Cycle ◽

Infected Cells ◽

Epstein Barr

Epstein–Barr virus (EBV) is an oncogenic herpesvirus that has been causally linked to the development of B-cell and epithelial malignancies. Early after infection, EBV induces a transient period of hyperproliferation that is suppressed by the activation of the DNA damage response and a G1/S-phase growth arrest. This growth arrest prevents long-term outgrowth of the majority of infected cells. We developed a method to isolate and characterize infected cells that arrest after this early burst of proliferation and integrated gene expression and metabolic profiling to gain a better understanding of the pathways that attenuate immortalization. We found that the arrested cells have a reduced level of mitochondrial respiration and a decrease in the expression of genes involved in the TCA cycle and oxidative phosphorylation. Indeed, the growth arrest in early infected cells could be rescued by supplementing the TCA cycle. Arrested cells were characterized by an increase in the expression of p53 pathway gene targets, including sestrins leading to activation of AMPK, a reduction in mTOR signaling, and, consequently, elevated autophagy that was important for cell survival. Autophagy was also critical to maintain early hyperproliferation during metabolic stress. Finally, in assessing the metabolic changes from early infection to long-term outgrowth, we found concomitant increases in glucose import and surface glucose transporter 1 (GLUT1) levels, leading to elevated glycolysis, oxidative phosphorylation, and suppression of basal autophagy. Our study demonstrates that oncogene-induced senescence triggered by a combination of metabolic and genotoxic stress acts as an intrinsic barrier to EBV-mediated transformation.

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