scholarly journals Role of pyruvate in maintaining cell viability and energy production under high-glucose conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hideji Yako ◽  
Naoko Niimi ◽  
Ayako Kato ◽  
Shizuka Takaku ◽  
Yasuaki Tatsumi ◽  
...  
Keyword(s):  
Cell Death ◽  
Schwann Cells ◽  
High Glucose ◽  
Energy Production ◽  
Parp Inhibitor ◽  
Vitamin B1 ◽  
Tca Cycle ◽  
Polyol Pathway ◽  
Glycolytic Flux ◽  
Atp Production

AbstractPyruvate functions as a key molecule in energy production and as an antioxidant. The efficacy of pyruvate supplementation in diabetic retinopathy and nephropathy has been shown in animal models; however, its significance in the functional maintenance of neurons and Schwann cells under diabetic conditions remains unknown. We observed rapid and extensive cell death under high-glucose (> 10 mM) and pyruvate-starved conditions. Exposure of Schwann cells to these conditions led to a significant decrease in glycolytic flux, mitochondrial respiration and ATP production, accompanied by enhanced collateral glycolysis pathways (e.g., polyol pathway). Cell death could be prevented by supplementation with 2-oxoglutarate (a TCA cycle intermediate), benfotiamine (the vitamin B1 derivative that suppresses the collateral pathways), or the poly (ADP-ribose) polymerase (PARP) inhibitor, rucaparib. Our findings suggest that exogenous pyruvate plays a pivotal role in maintaining glycolysis–TCA cycle flux and ATP production under high-glucose conditions by suppressing PARP activity.

scholarly journals Slow TCA flux implies low ATP production in tumors

2021 ◽  
Author(s):  
Caroline R. Bartman ◽  
Yihui Shen ◽  
Won Dong Lee ◽  
Tara TeSlaa ◽  
Connor S.R. Jankowski ◽  
...  
Keyword(s):  
Electron Transport ◽  
Warburg Effect ◽  
Electron Transport Chain ◽  
Aerobic Glycolysis ◽  
Tca Cycle ◽  
High Energy ◽  
Glycolytic Flux ◽  
Atp Production ◽  
Transport Chain ◽  
The Warburg Effect

SummaryThe tricarboxylic acid (TCA) cycle oxidizes carbon substrates to carbon dioxide, with the resulting high energy electrons fed into the electron transport chain to produce ATP by oxidative phosphorylation. Healthy tissues derive most of their ATP from oxidative metabolism, and the remainder from glycolysis. The corresponding balance in tumors remains unclear. Tumors upregulate aerobic glycolysis (the Warburg effect), yet they also typically require an intact TCA cycle and electron transport chain1–6. Recent studies have measured which nutrients contribute carbon to the tumor TCA metabolites7,8, but not tumor TCA flux: how fast the cycle turns. Here, we develop and validate an in vivo dynamic isotope tracing-mass spectrometry strategy for TCA flux quantitation, which we apply to all major mouse organs and to five tumor models. We show that, compared to the tissue of origin, tumor TCA flux is markedly suppressed. Complementary glycolytic flux measurements confirm tumor glycolysis acceleration, but the majority of tumor ATP is nevertheless made aerobically, and total tumor ATP production is suppressed compared to healthy tissues. In murine pancreatic cancer, this is accommodated by downregulation of the major energy-using pathway in the healthy exocrine pancreas, protein synthesis. Thus, instead of being hypermetabolic as commonly assumed, tumors apparently make ATP at a lower than normal rate. We propose that, as cells de-differentiate into cancer, they eschew ATP-intensive processes characteristic of the host tissue, and that the resulting suppressed ATP demand contributes to the Warburg effect and facilitates cancer growth in the nutrient-poor tumor microenvironment.

scholarly journals High glucose-induced activation of the polyol pathway and changes of gene expression profiles in immortalized adult mouse Schwann cells IMS32

2006 ◽  
Vol 98 (2) ◽  
pp. 446-458 ◽  
Author(s):  
Kazunori Sango ◽  
Takeshi Suzuki ◽  
Hiroko Yanagisawa ◽  
Shizuka Takaku ◽  
Hiroko Hirooka ◽  
...  
Keyword(s):  
Gene Expression ◽  
Schwann Cells ◽  
High Glucose ◽  
Adult Mouse ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Polyol Pathway

Supplement of TCA cycle intermediates protects against high glucose/palmitate-induced INS-1 beta cell death

2011 ◽  
Vol 505 (2) ◽  
pp. 231-241 ◽  
Author(s):  
Sung-E Choi ◽  
Youn-Jung Lee ◽  
Geum-Sook Hwang ◽  
Joo Hee Chung ◽  
Soo-Jin Lee ◽  
...  
Keyword(s):  
Cell Death ◽  
Beta Cell ◽  
High Glucose ◽  
Tca Cycle ◽  
Beta Cell Death ◽  
Tca Cycle Intermediates

scholarly journals Absence of retbindin blocks glycolytic flux, disrupts metabolic homeostasis, and leads to photoreceptor degeneration

2021 ◽  
Vol 118 (6) ◽  
pp. e2018956118
Author(s):  
Tirthankar Sinha ◽  
Jianhai Du ◽  
Mustafa S. Makia ◽  
James B. Hurley ◽  
Muna I. Naash ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Tca Cycle ◽  
Underlying Mechanism ◽  
Neural Retina ◽  
Pentose Phosphate ◽  
Metabolic Reprogramming ◽  
Glycolytic Flux ◽  
Acid Oxidation ◽  
Atp Production ◽  
Almost All

We previously reported a model of progressive retinal degeneration resulting from the knockout of the retina-specific riboflavin binding protein, retbindin (Rtbdn−/−). We also demonstrated a reduction in neural retinal flavins as a result of the elimination of RTBDN. Given the role of flavins in metabolism, herein we investigated the underlying mechanism of this retinal degeneration by performing metabolomic analyses on predegeneration at postnatal day (P) 45 and at the onset of functional degeneration in the P120 retinas. Metabolomics of hydrophilic metabolites revealed that individual glycolytic products accumulated in the P45 Rtbdn−/− neural retinas along with the elevation of pentose phosphate pathway, while TCA cycle intermediates remained unchanged. This was confirmed by using 13C-labeled flux measurements and immunoblotting, revealing that the key regulatory step of phosphoenolpyruvate to pyruvate was inhibited via down-regulation of the tetrameric pyruvate kinase M2 (PKM2). Separate metabolite assessments revealed that almost all intermediates of acylcarnitine fatty acid oxidation, ceramides, sphingomyelins, and multiple toxic metabolites were significantly elevated in the predegeneration Rtbdn−/− neural retina. Our data show that lack of RTBDN, and hence reduction in flavins, forced the neural retina into repurposing glucose for free-radical mitigation over ATP production. However, such sustained metabolic reprogramming resulted in an eventual metabolic collapse leading to neurodegeneration.

scholarly journals Bedaquiline reprograms central metabolism to reveal glycolytic vulnerability in Mycobacterium tuberculosis

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jared S. Mackenzie ◽  
Dirk A. Lamprecht ◽  
Rukaya Asmal ◽  
John H. Adamson ◽  
Khushboo Borah ◽  
...  
Keyword(s):  
Cell Death ◽  
Mycobacterium Tuberculosis ◽  
Metabolic Flux ◽  
Tca Cycle ◽  
Central Carbon Metabolism ◽  
Atp Production ◽  
Isotopomer Analysis ◽  
Metabolic Mechanism ◽  
Substantial Interest ◽  
Insight Into

AbstractThe approval of bedaquiline (BDQ) for the treatment of tuberculosis has generated substantial interest in inhibiting energy metabolism as a therapeutic paradigm. However, it is not known precisely how BDQ triggers cell death in Mycobacterium tuberculosis (Mtb). Using 13C isotopomer analysis, we show that BDQ-treated Mtb redirects central carbon metabolism to induce a metabolically vulnerable state susceptible to genetic disruption of glycolysis and gluconeogenesis. Metabolic flux profiles indicate that BDQ-treated Mtb is dependent on glycolysis for ATP production, operates a bifurcated TCA cycle by increasing flux through the glyoxylate shunt, and requires enzymes of the anaplerotic node and methylcitrate cycle. Targeting oxidative phosphorylation (OXPHOS) with BDQ and simultaneously inhibiting substrate level phosphorylation via genetic disruption of glycolysis leads to rapid sterilization. Our findings provide insight into the metabolic mechanism of BDQ-induced cell death and establish a paradigm for the development of combination therapies that target OXPHOS and glycolysis.

scholarly journals P0982PTEN-INDUCED KINASE 1 (PINK1) DEPLETION ALTERS MITOCHONDRIAL EFFICIENCY AND GLYCOLYSIS IN HUMAN PODOCYTES

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Irena Audzeyenka ◽  
Dorota Rogacka ◽  
Agnieszka Piwkowska
Keyword(s):  
Mitochondrial Biogenesis ◽  
High Glucose ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Basal Respiration ◽  
Glycolytic Flux ◽  
Atp Production ◽  
Filtration Barrier ◽  
Cell Energy

Abstract Background and Aims Podocytes are terminally differentiated cells, which constitute an inner layer of the renal filtration barrier. Podocytes are characterized by high metabolic activity, and their elevated energy requirements are met by maintaining the appropriate mitochondrial number and quality, which depend on mitochondrial biogenesis and mitophagy. Alteration of mitochondrial dynamics is linked to the development of insulin resistance and diabetes. The main goal of the research was to determine the role of mitophagy in podocytes bioenergetics and to elucidate the effects of hyperglycemia on mitochondrial dynamics. Method In order to inhibit mitophagy, we generated a human podocyte cell line stably expressing PINK1 shRNA through lentiviral transduction. Biochemical analyses were performed to assess the oxidative phosphorylation efficiency (by measurement of oxygen consumption rate; OCR) and glycolysis contribution to the total cell energy production (by measurement of extracellular acidification rate; ECAR) in the differentiated shPINK1 podocytes. The expression levels of mRNAs and proteins were evaluated in podocytes cultured in standard glucose (11 mM) and high glucose (30 mM) concentrations using real-time PCR and western blot. Intracellular mitochondrial network was visualized by MitoTrackertTM staining. The co-localization of proteins in podocytes was analysed by double immunofluorescence labelling and confocal microscopy. Results PINK1-deficiency resulted in the significant decrease of maximal respiration and spare respiratory capacity in podocytes (by 40% and 70%, respectively). Non-mitochondrial respiration was also decreased by 45% in shPINK1 cells. Interestingly, basal respiration and ATP production appeared similar in shPINK1 and control podocytes. PINK1 depletion increased glycolytic flux by 70%, in addition, the accompanying decline in glycolytic capacity and glycolytic reserve was observed (by 38% and 63%, respectively). Moreover, we observed accumulation of small and ring-shaped mitochondria in PINK1-deficient podocytes compared with the control cells. We showed a decreased expression of PINK1 and Parkin (mRNA and protein) in normal human podocytes cultured in hyperglycemic medium, which was associated with an elevated levels of mitochondrial fission markers (DRP1, FIS1) and with a decreased levels of PGC1α and TFAM, which play a role in mitochondrial biogenesis and mtDNA replication. Conclusion In this research, we demonstrated a novel role of mitophagy in podocyte bioenergetics. Moreover, we showed that high glucose inhibits mitophagy and promotes mitochondrial fission leading to the accumulation of damaged mitochondria and podocyte injury, which underlies the pathogenesis of diabetic nephropathy.

Neurotrophin-3-induced production of nerve growth factor is suppressed in Schwann cells exposed to high glucose: involvement of the polyol pathway

2004 ◽  
Vol 91 (6) ◽  
pp. 1430-1438 ◽  
Author(s):  
Takeshi Suzuki ◽  
Hiromi Sekido ◽  
Noriaki Kato ◽  
Yukiharu Nakayama ◽  
Chihiro Yabe-Nishimura
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Schwann Cells ◽  
High Glucose ◽  
Polyol Pathway ◽  
Nerve Growth ◽  
Neurotrophin 3

scholarly journals Aldose Reductase and the Polyol Pathway in Schwann Cells: Old and New Problems

2021 ◽  
Vol 22 (3) ◽  
pp. 1031
Author(s):  
Naoko Niimi ◽  
Hideji Yako ◽  
Shizuka Takaku ◽  
Sookja K. Chung ◽  
Kazunori Sango
Keyword(s):  
Schwann Cells ◽  
Aldose Reductase ◽  
Critical Role ◽  
Polyol Pathway ◽  
Glucose Flux ◽  
Rate Limiting ◽  
Deficient Mice ◽  
Excess Glucose ◽  
Shed Light ◽  
Immortalized Schwann Cells

Aldose reductase (AR) is a member of the reduced nicotinamide adenosine dinucleotide phosphate (NADPH)-dependent aldo-keto reductase superfamily. It is also the rate-limiting enzyme of the polyol pathway, catalyzing the conversion of glucose to sorbitol, which is subsequently converted to fructose by sorbitol dehydrogenase. AR is highly expressed by Schwann cells in the peripheral nervous system (PNS). The excess glucose flux through AR of the polyol pathway under hyperglycemic conditions has been suggested to play a critical role in the development and progression of diabetic peripheral neuropathy (DPN). Despite the intensive basic and clinical studies over the past four decades, the significance of AR over-activation as the pathogenic mechanism of DPN remains to be elucidated. Moreover, the expected efficacy of some AR inhibitors in patients with DPN has been unsatisfactory, which prompted us to further investigate and review the understanding of the physiological and pathological roles of AR in the PNS. Particularly, the investigation of AR and the polyol pathway using immortalized Schwann cells established from normal and AR-deficient mice could shed light on the causal relationship between the metabolic abnormalities of Schwann cells and discordance of axon-Schwann cell interplay in DPN, and led to the development of better therapeutic strategies against DPN.

scholarly journals LONP1 and ClpP cooperatively regulate mitochondrial proteostasis for cancer cell survival

Oncogenesis ◽  
2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Yu Geon Lee ◽  
Hui Won Kim ◽  
Yeji Nam ◽  
Kyeong Jin Shin ◽  
Yu Jin Lee ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Growth ◽  
Cell Survival ◽  
Cancer Cell ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Tca Cycle ◽  
Mitochondrial Matrix ◽  
Mitochondrial Functions ◽  
Cancer Cell Survival

AbstractMitochondrial proteases are key components in mitochondrial stress responses that maintain proteostasis and mitochondrial integrity in harsh environmental conditions, which leads to the acquisition of aggressive phenotypes, including chemoresistance and metastasis. However, the molecular mechanisms and exact role of mitochondrial proteases in cancer remain largely unexplored. Here, we identified functional crosstalk between LONP1 and ClpP, which are two mitochondrial matrix proteases that cooperate to attenuate proteotoxic stress and protect mitochondrial functions for cancer cell survival. LONP1 and ClpP genes closely localized on chromosome 19 and were co-expressed at high levels in most human cancers. Depletion of both genes synergistically attenuated cancer cell growth and induced cell death due to impaired mitochondrial functions and increased oxidative stress. Using mitochondrial matrix proteomic analysis with an engineered peroxidase (APEX)-mediated proximity biotinylation method, we identified the specific target substrates of these proteases, which were crucial components of mitochondrial functions, including oxidative phosphorylation, the TCA cycle, and amino acid and lipid metabolism. Furthermore, we found that LONP1 and ClpP shared many substrates, including serine hydroxymethyltransferase 2 (SHMT2). Inhibition of both LONP1 and ClpP additively increased the amount of unfolded SHMT2 protein and enhanced sensitivity to SHMT2 inhibitor, resulting in significantly reduced cell growth and increased cell death under metabolic stress. Additionally, prostate cancer patients with higher LONP1 and ClpP expression exhibited poorer survival. These results suggest that interventions targeting the mitochondrial proteostasis network via LONP1 and ClpP could be potential therapeutic strategies for cancer.

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