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Doerrier C, Gama-Perez P, Pesta D, Distefano G, Soendergaard SD, Chroeis KM, Gonzalez-Franquesa A, Goodpaster BH, Prats C, Sales-Pardo M, Guimera R, Coen PM, Gnaiger E, Larsen S, Garcia-Roves PM. Harmonization of experimental procedures to assess mitochondrial respiration in human permeabilized skeletal muscle fibers. Free Radic Biol Med 2024; 223:384-397. [PMID: 39097206 DOI: 10.1016/j.freeradbiomed.2024.07.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 07/11/2024] [Accepted: 07/29/2024] [Indexed: 08/05/2024]
Abstract
AIM High-resolution respirometry in human permeabilized muscle fibers is extensively used for analysis of mitochondrial adaptions to nutrition and exercise interventions, and is linked to athletic performance. However, the lack of standardization of experimental conditions limits quantitative inter- and intra-laboratory comparisons. METHODS In our study, an international team of investigators measured mitochondrial respiration of permeabilized muscle fibers obtained from three biopsies (vastus lateralis) from the same healthy volunteer to avoid inter-individual variability. High-resolution respirometry assays were performed together at the same laboratory to assess whether the heterogenity in published results are due to the effects of respiration media (MiR05 versus Z) with or without the myosin inhibitor blebbistatin at low- and high-oxygen regimes. RESULTS Our findings reveal significant differences between respiration media for OXPHOS and ETcapacities supported by NADH&succinate-linked substrates at different oxygen concentrations. Respiratory capacities were approximately 1.5-fold higher in MiR05 at high-oxygen regimes compared to medium Z near air saturation. The presence or absence of blebbistatin in human permeabilized muscle fiber preparations was without effect on oxygen flux. CONCLUSION Our study constitutes a basis to harmonize and establish optimum experimental conditions for respirometric studies of permeabilized human skeletal muscle fibers to improve reproducibility.
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Affiliation(s)
| | - Pau Gama-Perez
- Dept Physiological Sciences, Univ Barcelona and Bellvitge Biomedical Research Inst, Spain.
| | - Dominik Pesta
- Inst Clinical Diabetology, German Diabetes Center, Leibniz Center Diabetes Research Heinrich-Heine Univ Düsseldorf, Germany; German Center Diabetes Research, Munich, Neuherberg, Germany; Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany; Center for Endocrinology, Diabetes and Preventive Medicine (CEDP), University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany.
| | | | - Stine D Soendergaard
- Xlab, Dept Biomedical Sciences, Center Healthy Aging, Fac Health Sciences, Denmark.
| | | | - Alba Gonzalez-Franquesa
- The Novo Nordisk Center Basic Metabolic Research, Section Integrative Physiology, Univ Copenhagen, Denmark.
| | | | - Clara Prats
- Dept Biomedical Sciences, Center Healthy Aging, Fac Health Sciences, Denmark; The Core Facility for Integrated Microscopy, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
| | - Marta Sales-Pardo
- Dept of Chemical Engineering, Universitat Rovira I Virgili, Tarragona, Spain.
| | - Roger Guimera
- Dept of Chemical Engineering, Universitat Rovira I Virgili, Tarragona, Spain; Institució Catalana de Recerca I Estudis Avançats (ICREA), Barcelona, Spain.
| | - Paul M Coen
- Translational Research Institute AdventHealth, Orlando, FL, USA.
| | - Erich Gnaiger
- Oroboros Instruments, Schöpfstrasse 18, 6020, Innsbruck, Austria.
| | - Steen Larsen
- Xlab, Dept Biomedical Sciences, Center Healthy Aging, Fac Health Sciences, Denmark; Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland.
| | - Pablo M Garcia-Roves
- Dept Physiological Sciences, Univ Barcelona and Bellvitge Biomedical Research Inst, Spain.
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Donnelly C, Komlódi T, Cecatto C, Cardoso LHD, Compagnion AC, Matera A, Tavernari D, Campiche O, Paolicelli RC, Zanou N, Kayser B, Gnaiger E, Place N. Functional hypoxia reduces mitochondrial calcium uptake. Redox Biol 2024; 71:103037. [PMID: 38401291 PMCID: PMC10906399 DOI: 10.1016/j.redox.2024.103037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 12/20/2023] [Accepted: 01/10/2024] [Indexed: 02/26/2024] Open
Abstract
Mitochondrial respiration extends beyond ATP generation, with the organelle participating in many cellular and physiological processes. Parallel changes in components of the mitochondrial electron transfer system with respiration render it an appropriate hub for coordinating cellular adaption to changes in oxygen levels. How changes in respiration under functional hypoxia (i.e., when intracellular O2 levels limit mitochondrial respiration) are relayed by the electron transfer system to impact mitochondrial adaption and remodeling after hypoxic exposure remains poorly defined. This is largely due to challenges integrating findings under controlled and defined O2 levels in studies connecting functions of isolated mitochondria to humans during physical exercise. Here we present experiments under conditions of hypoxia in isolated mitochondria, myotubes and exercising humans. Performing steady-state respirometry with isolated mitochondria we found that oxygen limitation of respiration reduced electron flow and oxidative phosphorylation, lowered the mitochondrial membrane potential difference, and decreased mitochondrial calcium influx. Similarly, in myotubes under functional hypoxia mitochondrial calcium uptake decreased in response to sarcoplasmic reticulum calcium release for contraction. In both myotubes and human skeletal muscle this blunted mitochondrial adaptive responses and remodeling upon contractions. Our results suggest that by regulating calcium uptake the mitochondrial electron transfer system is a hub for coordinating cellular adaption under functional hypoxia.
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Affiliation(s)
- Chris Donnelly
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland; Oroboros Instruments, Innsbruck, Austria.
| | | | | | | | | | - Alessandro Matera
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Daniele Tavernari
- Department of Computational Biology, University of Lausanne, Lausanne, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland; Swiss Cancer Centre Léman, Lausanne, Switzerland
| | - Olivier Campiche
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | | | - Nadège Zanou
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Bengt Kayser
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | | | - Nicolas Place
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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3
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Kowalewska PM, Milkovich SL, Goldman D, Sandow SL, Ellis CG, Welsh DG. Capillary oxygen regulates demand-supply coupling by triggering connexin40-mediated conduction: Rethinking the metabolic hypothesis. Proc Natl Acad Sci U S A 2024; 121:e2303119121. [PMID: 38349880 PMCID: PMC10895355 DOI: 10.1073/pnas.2303119121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 12/21/2023] [Indexed: 02/15/2024] Open
Abstract
Coupling red blood cell (RBC) supply to O2 demand is an intricate process requiring O2 sensing, generation of a stimulus, and signal transduction that alters upstream arteriolar tone. Although actively debated, this process has been theorized to be induced by hypoxia and to involve activation of endothelial inwardly rectifying K+ channels (KIR) 2.1 by elevated extracellular K+ to trigger conducted hyperpolarization via connexin40 (Cx40) gap junctions to upstream resistors. This concept was tested in resting healthy skeletal muscle of Cx40-/- and endothelial KIR2.1-/- mice using state-of-the-art live animal imaging where the local tissue O2 environment was manipulated using a custom gas chamber. Second-by-second capillary RBC flow responses were recorded as O2 was altered. A stepwise drop in PO2 at the muscle surface increased RBC supply in capillaries of control animals while elevated O2 elicited the opposite response; capillaries were confirmed to express Cx40. The RBC flow responses were rapid and tightly coupled to O2; computer simulations did not support hypoxia as a driving factor. In contrast, RBC flow responses were significantly diminished in Cx40-/- mice. Endothelial KIR2.1-/- mice, on the other hand, reacted normally to O2 changes, even when the O2 challenge was targeted to a smaller area of tissue with fewer capillaries. Conclusively, microvascular O2 responses depend on coordinated electrical signaling via Cx40 gap junctions, and endothelial KIR2.1 channels do not initiate the event. These findings reconceptualize the paradigm of blood flow regulation in skeletal muscle and how O2 triggers this process in capillaries independent of extracellular K+.
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Affiliation(s)
- Paulina M. Kowalewska
- Robarts Research Institute, University of Western Ontario, London, ONN6A 5B7, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ONN6A 5B7, Canada
| | | | - Daniel Goldman
- Department of Medical Biophysics, University of Western Ontario, London, ONN6A 5B7, Canada
| | - Shaun L. Sandow
- School of Health, University of the Sunshine Coast, Maroochydore, QLD4556, Australia
- School of Clinical Medicine, University of Queensland, St. Lucia, QLD4072, Australia
| | - Christopher G. Ellis
- Robarts Research Institute, University of Western Ontario, London, ONN6A 5B7, Canada
- Department of Medical Biophysics, University of Western Ontario, London, ONN6A 5B7, Canada
| | - Donald G. Welsh
- Robarts Research Institute, University of Western Ontario, London, ONN6A 5B7, Canada
- Department of Physiology and Pharmacology, University of Western Ontario, London, ONN6A 5B7, Canada
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4
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Lee SCES, Pyo AHA, Koritzinsky M. Longitudinal dynamics of the tumor hypoxia response: From enzyme activity to biological phenotype. SCIENCE ADVANCES 2023; 9:eadj6409. [PMID: 37992163 PMCID: PMC10664991 DOI: 10.1126/sciadv.adj6409] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 10/23/2023] [Indexed: 11/24/2023]
Abstract
Poor oxygenation (hypoxia) is a common spatially heterogeneous feature of human tumors. Biological responses to tumor hypoxia are orchestrated by the decreased activity of oxygen-dependent enzymes. The affinity of these enzymes for oxygen positions them along a continuum of oxygen sensing that defines their roles in launching reactive and adaptive cellular responses. These responses encompass regulation of all steps in the central dogma, with rapid perturbation of the metabolome and proteome followed by more persistent reprogramming of the transcriptome and epigenome. Core hypoxia response genes and pathways are commonly regulated at multiple inflection points, fine-tuning the dependencies on oxygen concentration and hypoxia duration. Ultimately, shifts in the activity of oxygen-sensing enzymes directly or indirectly endow cells with intrinsic hypoxia tolerance and drive processes that are associated with aggressive phenotypes in cancer including angiogenesis, migration, invasion, immune evasion, epithelial mesenchymal transition, and stemness.
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Affiliation(s)
- Sandy Che-Eun S. Lee
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Andrea Hye An Pyo
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Marianne Koritzinsky
- Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
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5
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Wagner PD. Determinants of maximal oxygen consumption. J Muscle Res Cell Motil 2023; 44:73-88. [PMID: 36434438 DOI: 10.1007/s10974-022-09636-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 10/20/2022] [Indexed: 11/27/2022]
Abstract
This article lays out the determinants of maximal O2 consumption (VO2max) achieved during high intensity endurance exercise. It is not a traditional topical review but rather an educational essay that intertwines chance observations made during an unrelated research project with a subsequent program of stepwise thought, analysis and experimentation to reveal how O2 is delivered to and used by the mitochondria. The centerpiece is the recognition that O2 is delivered by an inter-dependent system of transport components functioning as a "bucket brigade", made up of the lungs, heart, blood and circulation, and the muscles themselves, each of which affects O2 transport by similar amounts as they change. There is thus no single "limiting factor" to VO2max. Moreover, each component is shown to quantitatively affect the performance of the others. Mitochondrial respiration is integrated into the O2 transport system analysis to reveal its separate contribution to VO2max, and to show that mitochondrial PO2 at VO2max must be extremely low. Clinical application of the O2 transport systems analysis is described to separate central cardiopulmonary from peripheral tissue contributions to exercise limitation, illustrated by a study of patients with COPD. Finally, a short discussion of why muscles operating maximally must endure an almost anoxic state is offered. The hope is that in sum, both the increased understanding of O2 transport and the scientific approach to achieving that understanding described in the review can serve as a model for solving other complex problems going forward.
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6
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Devaux JBL, Hedges CP, Birch N, Herbert N, Renshaw GMC, Hickey AJR. Electron transfer and ROS production in brain mitochondria of intertidal and subtidal triplefin fish (Tripterygiidae). J Comp Physiol B 2023:10.1007/s00360-023-01495-4. [PMID: 37145369 DOI: 10.1007/s00360-023-01495-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/01/2023] [Accepted: 04/27/2023] [Indexed: 05/06/2023]
Abstract
While oxygen is essential for oxidative phosphorylation, O2 can form reactive species (ROS) when interacting with electrons of mitochondrial electron transport system. ROS is dependent on O2 pressure (PO2) and has traditionally been assessed in O2 saturated media, PO2 at which mitochondria do not typically function in vivo. Mitochondrial ROS can be significantly elevated by the respiratory complex II substrate succinate, which can accumulate within hypoxic tissues, and this is exacerbated further with reoxygenation. Intertidal species are repetitively exposed to extreme O2 fluctuations, and have likely evolved strategies to avoid excess ROS production. We evaluated mitochondrial electron leakage and ROS production in permeabilized brain of intertidal and subtidal triplefin fish species from hyperoxia to anoxia, and assessed the effect of anoxia reoxygenation and the influence of increasing succinate concentrations. At typical intracellular PO2, net ROS production was similar among all species; however at elevated PO2, brain tissues of the intertidal triplefin fish released less ROS than subtidal species. In addition, following in vitro anoxia reoxygenation, electron transfer mediated by succinate titration was better directed to respiration, and not to ROS production for intertidal species. Overall, these data indicate that intertidal triplefin fish species better manage electrons within the ETS, from hypoxic-hyperoxic transitions.
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Affiliation(s)
- Jules B L Devaux
- School of Biological Sciences, The University of Auckland, Auckland Mail Centre, Private Bag 92019, Auckland, 1142, New Zealand.
| | - Chris P Hedges
- School of Biological Sciences, The University of Auckland, Auckland Mail Centre, Private Bag 92019, Auckland, 1142, New Zealand
| | - Nigel Birch
- School of Biological Sciences, The University of Auckland, Auckland Mail Centre, Private Bag 92019, Auckland, 1142, New Zealand
| | - Neill Herbert
- Institute of Marine Science, The University Auckland, Auckland, 1142, New Zealand
| | - Gillian M C Renshaw
- School of Allied Health Sciences, Griffith University, Gold Coast Campus, Gold Coast, QLD, 4222, Australia
| | - Anthony J R Hickey
- School of Biological Sciences, The University of Auckland, Auckland Mail Centre, Private Bag 92019, Auckland, 1142, New Zealand
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7
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Köhler D, Voshaar T, Stais P, Haidl P, Dellweg D. Hypoxische, anämische und kardial bedingte Hypoxämie: Wann beginnt die Hypoxie im Gewebe? Dtsch Med Wochenschr 2023; 148:475-482. [PMID: 36990120 DOI: 10.1055/a-2007-5450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
ZusammenfassungBei einer Hypoxämie ist oft der Sauerstoffgehalt noch im unteren Normbereich, sodass keine
Hypoxie im Gewebe vorliegt. Wird die Hypoxie-Schwelle im Gewebe bei einer hypoxisch, anämisch
und auch kardial bedingten Hypoxämie erreicht, kommt es im Zellstoffwechsel, unabhängig von
der Genese, zu identischen Gegenregulationen. Im klinischen Alltag wird diese
pathophysiologische Tatsache mitunter ignoriert, obwohl je nach Hypoxämie-Ursache die
Beurteilung und die Therapie stark unterschiedlich sind. Während für die anämische Hypoxämie
restriktive und allgemein akzeptierte Regeln in den Transfusionsrichtlinien festgelegt sind,
wird bei einer hypoxischen Hypoxie früh die Indikation zu einer meist invasiven Beatmung
gestellt. Die klinische Beurteilung und Indikationsstellung fokussiert dabei auf die Parameter
Sauerstoffsättigung, Sauerstoffpartialdruck und Oxygenierungsindex. Während der
Corona-Pandemie sind Fehlinterpretationen der Pathophysiologie sichtbar geworden und haben
vermutlich zu überflüssigen Intubationen geführt. Für die Behandlung einer hypoxischen Hypoxie
mittels invasiver Beatmung aber gibt es keine Evidenz. Im vorliegenden Review wird auf die
Pathophysiologie der verschiedenen Hypoxieursachen unter besonderer Berücksichtigung der
Intubation und Beatmung auf der Intensivstation eingegangen.
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8
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Computational Modeling and Imaging of the Intracellular Oxygen Gradient. Int J Mol Sci 2022; 23:ijms232012597. [PMID: 36293452 PMCID: PMC9604273 DOI: 10.3390/ijms232012597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/13/2022] [Accepted: 10/17/2022] [Indexed: 11/30/2022] Open
Abstract
Computational modeling can provide a mechanistic and quantitative framework for describing intracellular spatial heterogeneity of solutes such as oxygen partial pressure (pO2). This study develops and evaluates a finite-element model of oxygen-consuming mitochondrial bioenergetics using the COMSOL Multiphysics program. The model derives steady-state oxygen (O2) distributions from Fickian diffusion and Michaelis–Menten consumption kinetics in the mitochondria and cytoplasm. Intrinsic model parameters such as diffusivity and maximum consumption rate were estimated from previously published values for isolated and intact mitochondria. The model was compared with experimental data collected for the intracellular and mitochondrial pO2 levels in human cervical cancer cells (HeLa) in different respiratory states and under different levels of imposed pO2. Experimental pO2 gradients were measured using lifetime imaging of a Förster resonance energy transfer (FRET)-based O2 sensor, Myoglobin-mCherry, which offers in situ real-time and noninvasive measurements of subcellular pO2 in living cells. On the basis of these results, the model qualitatively predicted (1) the integrated experimental data from mitochondria under diverse experimental conditions, and (2) the impact of changes in one or more mitochondrial processes on overall bioenergetics.
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Hypothermia Alleviates Reductive Stress, a Root Cause of Ischemia Reperfusion Injury. Int J Mol Sci 2022; 23:ijms231710108. [PMID: 36077504 PMCID: PMC9456258 DOI: 10.3390/ijms231710108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 11/17/2022] Open
Abstract
Ischemia reperfusion injury is common in transplantation. Previous studies have shown that cooling can protect against hypoxic injury. To date, the protective effects of hypothermia have been largely associated with metabolic suppression. Since kidney transplantation is one of the most common organ transplant surgeries, we used human-derived renal proximal tubular cells (HKC8 cell line) as a model of normal renal cells. We performed a temperature titration curve from 37 °C to 22 °C and evaluated cellular respiration and molecular mechanisms that can counteract the build-up of reducing equivalents in hypoxic conditions. We show that the protective effects of hypothermia are likely to stem both from metabolic suppression (inhibitory component) and augmentation of stress tolerance (activating component), with the highest overlap between activating and suppressing mechanisms emerging in the window of mild hypothermia (32 °C). Hypothermia decreased hypoxia-induced rise in the extracellular lactate:pyruvate ratio, increased ATP/ADP ratio and mitochondrial content, normalized lipid content, and improved the recovery of respiration after anoxia. Importantly, it was observed that in contrast to mild hypothermia, moderate and deep hypothermia interfere with HIF1 (hypoxia inducible factor 1)-dependent HRE (hypoxia response element) induction in hypoxia. This work also demonstrates that hypothermia alleviates reductive stress, a conceptually novel and largely overlooked phenomenon at the root of ischemia reperfusion injury.
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10
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Zdrazilova L, Hansikova H, Gnaiger E. Comparable respiratory activity in attached and suspended human fibroblasts. PLoS One 2022; 17:e0264496. [PMID: 35239701 PMCID: PMC8893708 DOI: 10.1371/journal.pone.0264496] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 02/11/2022] [Indexed: 11/19/2022] Open
Abstract
Measurement of oxygen consumption of cultured cells is widely used for diagnosis of mitochondrial diseases, drug testing, biotechnology, and toxicology. Fibroblasts are cultured in monolayers, but physiological measurements are carried out in suspended or attached cells. We address the question whether respiration differs in attached versus suspended cells using multiwell respirometry (Agilent Seahorse XF24) and high-resolution respirometry (Oroboros O2k), respectively. Respiration of human dermal fibroblasts measured in culture medium was baseline-corrected for residual oxygen consumption and expressed as oxygen flow per cell. No differences were observed between attached and suspended cells in ROUTINE respiration of living cells and LEAK respiration obtained after inhibition of ATP synthase by oligomycin. The electron transfer capacity was higher in the O2k than in the XF24. This could be explained by a limitation to two uncoupler titrations in the XF24 which led to an underestimation compared to multiple titration steps in the O2k. A quantitative evaluation of respiration measured via different platforms revealed that short-term suspension of fibroblasts did not affect respiratory activity and coupling control. Evaluation of results obtained by different platforms provides a test for reproducibility beyond repeatability. Repeatability and reproducibility are required for building a validated respirometric database.
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Affiliation(s)
- Lucie Zdrazilova
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General Hospital in Prague, Prague, Czechia
- * E-mail: (LZ); (EG)
| | - Hana Hansikova
- Department of Pediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General Hospital in Prague, Prague, Czechia
| | - Erich Gnaiger
- Oroboros Instruments, Innsbruck, Austria
- * E-mail: (LZ); (EG)
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11
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Tumor Hypoxia as a Barrier in Cancer Therapy: Why Levels Matter. Cancers (Basel) 2021; 13:cancers13030499. [PMID: 33525508 PMCID: PMC7866096 DOI: 10.3390/cancers13030499] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/22/2021] [Accepted: 01/23/2021] [Indexed: 02/07/2023] Open
Abstract
Simple Summary Hypoxia is a common feature of solid tumors and associated with poor outcome in most cancer types and treatment modalities, including radiotherapy, chemotherapy, surgery and, most likely, immunotherapy. Emerging strategies, such as proton therapy and combination therapies with radiation and hypoxia targeted drugs, provide new opportunities to overcome the hypoxia barrier and improve therapeutic outcome. Hypoxia is heterogeneously distributed both between and within tumors and shows large variations across patients not only in prevalence, but importantly, also in level. To best exploit the emerging strategies, a better understanding of how individual hypoxia levels from mild to severe affect tumor biology is vital. Here, we discuss our current knowledge on this topic and how we should proceed to gain more insight into the field. Abstract Hypoxia arises in tumor regions with insufficient oxygen supply and is a major barrier in cancer treatment. The distribution of hypoxia levels is highly heterogeneous, ranging from mild, almost non-hypoxic, to severe and anoxic levels. The individual hypoxia levels induce a variety of biological responses that impair the treatment effect. A stronger focus on hypoxia levels rather than the absence or presence of hypoxia in our investigations will help development of improved strategies to treat patients with hypoxic tumors. Current knowledge on how hypoxia levels are sensed by cancer cells and mediate cellular responses that promote treatment resistance is comprehensive. Recently, it has become evident that hypoxia also has an important, more unexplored role in the interaction between cancer cells, stroma and immune cells, influencing the composition and structure of the tumor microenvironment. Establishment of how such processes depend on the hypoxia level requires more advanced tumor models and methodology. In this review, we describe promising model systems and tools for investigations of hypoxia levels in tumors. We further present current knowledge and emerging research on cellular responses to individual levels, and discuss their impact in novel therapeutic approaches to overcome the hypoxia barrier.
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12
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Li Puma LC, Hedges M, Heckman JM, Mathias AB, Engstrom MR, Brown AB, Chicco AJ. Experimental oxygen concentration influences rates of mitochondrial hydrogen peroxide release from cardiac and skeletal muscle preparations. Am J Physiol Regul Integr Comp Physiol 2020; 318:R972-R980. [PMID: 32233925 DOI: 10.1152/ajpregu.00227.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mitochondria utilize the majority of oxygen (O2) consumed by aerobic organisms as the final electron acceptor for oxidative phosphorylation (OXPHOS) but also to generate reactive oxygen species (mtROS) that participate in cell signaling, physiological hormesis, and disease pathogenesis. Simultaneous monitoring of mtROS production and oxygen consumption (Jo2) from tissue mitochondrial preparations is an attractive investigative approach, but it introduces dynamic changes in media O2 concentration ([O2]) that can confound experimental results and interpretation. We utilized high-resolution fluorespirometry to evaluate Jo2 and hydrogen peroxide release (Jh2o2) from isolated mitochondria (Mt), permeabilized fibers (Pf), and tissue homogenates (Hm) prepared from murine heart and skeletal muscle across a range of experimental [O2]s typically encountered during respirometry protocols (400-50 µM). Results demonstrate notable variations in Jh2o2 across tissues and sample preparations during nonphosphorylating (LEAK) and OXPHOS-linked respiration states at 250 µM [O2] but a linear decline in Jh2o2 of 5-15% per 50-µM decrease in chamber [O2] in all samples. Jo2 was generally stable in Mt and Hm across [O2]s above 50 µM but tended to decline below 250 µM in Pf, leading to wide variations in assayed rates of Jh2o2/O2 across chamber [O2]s and sample preparations. Development of chemical background fluorescence from the H2O2 probe (Amplex Red) was also O2 sensitive, emphasizing relevant calibration considerations. This study highlights the importance of monitoring and reporting the chamber [O2] at which Jo2 and Jh2o2 are recorded during fluorespirometry experiments and provides a basis for selecting sample preparations for studies addressing the role of mtROS in physiology and disease.
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Affiliation(s)
- Lance C Li Puma
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Michael Hedges
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado
| | - Joseph M Heckman
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Alissa B Mathias
- Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado
| | - Madison R Engstrom
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Abigail B Brown
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado
| | - Adam J Chicco
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado.,Program in Cell and Molecular Biology, Colorado State University, Fort Collins, Colorado
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13
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Pajuelo Reguera D, Čunátová K, Vrbacký M, Pecinová A, Houštěk J, Mráček T, Pecina P. Cytochrome c Oxidase Subunit 4 Isoform Exchange Results in Modulation of Oxygen Affinity. Cells 2020; 9:cells9020443. [PMID: 32075102 PMCID: PMC7072730 DOI: 10.3390/cells9020443] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/11/2020] [Accepted: 02/11/2020] [Indexed: 01/05/2023] Open
Abstract
Cytochrome c oxidase (COX) is regulated through tissue-, development- or environment-controlled expression of subunit isoforms. The COX4 subunit is thought to optimize respiratory chain function according to oxygen-controlled expression of its isoforms COX4i1 and COX4i2. However, biochemical mechanisms of regulation by the two variants are only partly understood. We created an HEK293-based knock-out cellular model devoid of both isoforms (COX4i1/2 KO). Subsequent knock-in of COX4i1 or COX4i2 generated cells with exclusive expression of respective isoform. Both isoforms complemented the respiratory defect of COX4i1/2 KO. The content, composition, and incorporation of COX into supercomplexes were comparable in COX4i1- and COX4i2-expressing cells. Also, COX activity, cytochrome c affinity, and respiratory rates were undistinguishable in cells expressing either isoform. Analysis of energy metabolism and the redox state in intact cells uncovered modestly increased preference for mitochondrial ATP production, consistent with the increased NADH pool oxidation and lower ROS in COX4i2-expressing cells in normoxia. Most remarkable changes were uncovered in COX oxygen kinetics. The p50 (partial pressure of oxygen at half-maximal respiration) was increased twofold in COX4i2 versus COX4i1 cells, indicating decreased oxygen affinity of the COX4i2-containing enzyme. Our finding supports the key role of the COX4i2-containing enzyme in hypoxia-sensing pathways of energy metabolism.
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Affiliation(s)
- David Pajuelo Reguera
- Department of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech Republic; (D.P.R.); (K.Č.); (M.V.); (A.P.); (J.H.)
| | - Kristýna Čunátová
- Department of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech Republic; (D.P.R.); (K.Č.); (M.V.); (A.P.); (J.H.)
- Department of Cell Biology, Faculty of Science, Charles University, 12000 Prague 2, Czech Republic
| | - Marek Vrbacký
- Department of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech Republic; (D.P.R.); (K.Č.); (M.V.); (A.P.); (J.H.)
| | - Alena Pecinová
- Department of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech Republic; (D.P.R.); (K.Č.); (M.V.); (A.P.); (J.H.)
| | - Josef Houštěk
- Department of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech Republic; (D.P.R.); (K.Č.); (M.V.); (A.P.); (J.H.)
| | - Tomáš Mráček
- Department of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech Republic; (D.P.R.); (K.Č.); (M.V.); (A.P.); (J.H.)
- Correspondence: (T.M.); (P.P.)
| | - Petr Pecina
- Department of Bioenergetics, Institute of Physiology, Czech Academy of Sciences, 14220 Prague 4, Czech Republic; (D.P.R.); (K.Č.); (M.V.); (A.P.); (J.H.)
- Correspondence: (T.M.); (P.P.)
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14
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Begicevic RR, Arfuso F, Falasca M. Bioactive lipids in cancer stem cells. World J Stem Cells 2019; 11:693-704. [PMID: 31616544 PMCID: PMC6789187 DOI: 10.4252/wjsc.v11.i9.693] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/08/2019] [Accepted: 08/20/2019] [Indexed: 02/06/2023] Open
Abstract
Tumours are known to be a heterogeneous group of cells, which is why they are difficult to eradicate. One possible cause for this is the existence of slow-cycling cancer stem cells (CSCs) endowed with stem cell-like properties of self-renewal, which are responsible for resistance to chemotherapy and radiotherapy. In recent years, the role of lipid metabolism has garnered increasing attention in cancer. Specifically, the key roles of enzymes such as stearoyl-CoA desaturase-1 and 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase in CSCs, have gained particular interest. However, despite accumulating evidence on the role of proteins in controlling lipid metabolism, very little is known about the specific role played by lipid products in CSCs. This review highlights recent findings on the role of lipid metabolism in CSCs, focusing on the specific mechanism by which bioactive lipids regulate the fate of CSCs and their involvement in signal transduction pathways.
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Affiliation(s)
- Romana-Rea Begicevic
- Metabolic Signalling Group, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Frank Arfuso
- Stem Cell and Cancer Biology Laboratory, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Marco Falasca
- Metabolic Signalling Group, School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia.
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15
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Kohler K, Nallapareddy S, Ercole A. In Silico Model of Critical Cerebral Oxygenation after Traumatic Brain Injury: Implications for Rescuing Hypoxic Tissue. J Neurotrauma 2019; 36:2109-2116. [DOI: 10.1089/neu.2018.6187] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Katharina Kohler
- Division of Anaesthesia, University of Cambridge, Addenbrookes Hospital, Cambridge, United Kingdom
| | | | - Ari Ercole
- Division of Anaesthesia, University of Cambridge, Addenbrookes Hospital, Cambridge, United Kingdom
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16
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Cytotoxicity of xyloglucan from Copaifera langsdorffii and its complex with oxovanadium (IV/V) on B16F10 cells. Int J Biol Macromol 2019; 121:1019-1028. [DOI: 10.1016/j.ijbiomac.2018.10.131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 09/25/2018] [Accepted: 10/15/2018] [Indexed: 11/17/2022]
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17
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Hirai DM, Colburn TD, Craig JC, Hotta K, Kano Y, Musch TI, Poole DC. Skeletal muscle interstitial O 2 pressures: bridging the gap between the capillary and myocyte. Microcirculation 2018; 26:e12497. [PMID: 30120845 DOI: 10.1111/micc.12497] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/26/2018] [Accepted: 08/13/2018] [Indexed: 01/18/2023]
Abstract
The oxygen transport pathway from air to mitochondria involves a series of transfer steps within closely integrated systems (pulmonary, cardiovascular, and tissue metabolic). Small and finite O2 stores in most mammalian species require exquisitely controlled changes in O2 flux rates to support elevated ATP turnover. This is especially true for the contracting skeletal muscle where O2 requirements may increase two orders of magnitude above rest. This brief review focuses on the mechanistic bases for increased microvascular blood-myocyte O2 flux (V̇O2 ) from rest to contractions. Fick's law dictates that V̇O2 elevations driven by muscle contractions are produced by commensurate changes in driving force (ie, O2 pressure gradients; ΔPO2 ) and/or effective diffusing capacity (DO2 ). While previous evidence indicates that increased DO2 helps modulate contracting muscle O2 flux, up until recently the role of the dynamic ΔPO2 across the capillary wall was unknown. Recent phosphorescence quenching investigations of both microvascular and novel interstitial PO2 kinetics in health have resolved an important step in the O2 cascade between the capillary and myocyte. Specifically, the significant transmural ΔPO2 at rest was sustained (but not increased) during submaximal contractions. This supports the contention that the blood-myocyte interface provides a substantial effective resistance to O2 diffusion and underscores that modulations in erythrocyte hemodynamics and distribution (DO2 ) are crucial to preserve the driving force for O2 flux across the capillary wall (ΔPO2 ) during contractions. Investigation of the O2 transport pathway close to muscle mitochondria is key to identifying disease mechanisms and develop therapeutic approaches to ameliorate dysfunction and exercise intolerance.
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Affiliation(s)
- Daniel M Hirai
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jesse C Craig
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - Kazuki Hotta
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Timothy I Musch
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, Kansas
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18
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Fernandez HR, Gadre SM, Tan M, Graham GT, Mosaoa R, Ongkeko MS, Kim KA, Riggins RB, Parasido E, Petrini I, Pacini S, Cheema A, Varghese R, Ressom HW, Zhang Y, Albanese C, Üren A, Paige M, Giaccone G, Avantaggiati ML. The mitochondrial citrate carrier, SLC25A1, drives stemness and therapy resistance in non-small cell lung cancer. Cell Death Differ 2018; 25:1239-1258. [PMID: 29651165 PMCID: PMC6030199 DOI: 10.1038/s41418-018-0101-z] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/08/2018] [Accepted: 03/02/2018] [Indexed: 12/21/2022] Open
Abstract
Therapy resistance represents a clinical challenge for advanced non-small cell lung cancer (NSCLC), which still remains an incurable disease. There is growing evidence that cancer-initiating or cancer stem cells (CSCs) provide a reservoir of slow-growing dormant populations of cells with tumor-initiating and unlimited self-renewal ability that are left behind by conventional therapies reigniting post-therapy relapse and metastatic dissemination. The metabolic pathways required for the expansion of CSCs are incompletely defined, but their understanding will likely open new therapeutic opportunities. We show here that lung CSCs rely upon oxidative phosphorylation for energy production and survival through the activity of the mitochondrial citrate transporter, SLC25A1. We demonstrate that SLC25A1 plays a key role in maintaining the mitochondrial pool of citrate and redox balance in CSCs, whereas its inhibition leads to reactive oxygen species build-up thereby inhibiting the self-renewal capability of CSCs. Moreover, in different patient-derived tumors, resistance to cisplatin or to epidermal growth factor receptor (EGFR) inhibitor treatment is acquired through SLC25A1-mediated implementation of mitochondrial activity and induction of a stemness phenotype. Hence, a newly identified specific SLC25A1 inhibitor is synthetic lethal with cisplatin or with EGFR inhibitor co-treatment and restores antitumor responses to these agents in vitro and in animal models. These data have potential clinical implications in that they unravel a metabolic vulnerability of drug-resistant lung CSCs, identify a novel SLC25A1 inhibitor and, lastly, provide the first line of evidence that drugs, which block SLC25A1 activity, when employed in combination with selected conventional antitumor agents, lead to a therapeutic benefit.
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Affiliation(s)
- Harvey R Fernandez
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Shreyas M Gadre
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Mingjun Tan
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Garrett T Graham
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Rami Mosaoa
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Martin S Ongkeko
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Kyu Ah Kim
- Chemistry and Biochemistry Department, George Mason University, Fairfax, VA, USA
| | - Rebecca B Riggins
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Erika Parasido
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Iacopo Petrini
- Department of Clinical and Experimental Medicine, Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine University of Pisa, Pisa, Italy
| | - Simone Pacini
- Department of Clinical and Experimental Medicine, Department of Surgical, Medical and Molecular Pathology and Critical Care Medicine University of Pisa, Pisa, Italy
| | - Amrita Cheema
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Rency Varghese
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Habtom W Ressom
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Yuwen Zhang
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Christopher Albanese
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Aykut Üren
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Mikell Paige
- Chemistry and Biochemistry Department, George Mason University, Fairfax, VA, USA
| | - Giuseppe Giaccone
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA
| | - Maria Laura Avantaggiati
- Georgetown University Medical Center, Lombardi Comprehensive Cancer Center, Washington D.C, 20057, USA.
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19
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Golub AS, Dodhy SC, Pittman RN. Oxygen dependence of respiration in rat spinotrapezius muscle contracting at 0.5-8 twitches per second. J Appl Physiol (1985) 2018; 125:124-133. [PMID: 29494286 DOI: 10.1152/japplphysiol.01136.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The oxygen dependence of respiration was obtained in situ in microscopic regions of rat spinotrapezius muscle for different levels of metabolic activity produced by electrical stimulation at rates from 0.5 to 8 Hz. The rate of O2 consumption (V̇o2) was measured with phosphorescence quenching microscopy (PQM) as the rate of O2 disappearance in a muscle with rapid flow arrest. The phosphorescent oxygen probe was loaded into the interstitial space of the muscle to give O2 tension (Po2) in the interstitium. A set of sigmoid curves relating the Po2 dependence of V̇o2 was obtained with a Po2-dependent region below a characteristic Po2 (~30 mmHg) and a Po2-independent region above this Po2. The V̇o2(Po2) plots were fit by the Hill equation containing O2 demand (rest to 8 Hz: 216 ± 26 to 636 ± 77 nl O2/cm3 s) and the Po2 value corresponding to O2 demand/2 (rest to 8 Hz: 22 ± 4 to 11 ± 1 mmHg). The initial Po2 and V̇o2 pairs of values measured at the moment of flow arrest formed a straight line, determining the rate of oxygen supply. This line had a negative slope, equal to the oxygen conductance for the O2 supply chain. For each level of tissue blood flow the set of possible values of Po2 and V̇o2 consists of the intersection points between this O2 supply line and the set of V̇o2 curves. An electrical analogy for the intraorgan O2 supply and consumption is an inverting transistor amplifier, which allows the use of graphic analysis methods for prediction of the behavior of the oxygen processing system in organs. NEW & NOTEWORTHY The sigmoidal shape of curves describing oxygen dependence of muscle respiration varies from basal to maximal workload and characterizes the oxidative metabolism of muscle. The rate of O2 supply depends on extracellular O2 tension and is determined by the overall oxygen conductance in the muscle. The dynamics of oxygen consumption is determined by the supply line that intersects the oxygen demand curves. An electrical analogy for the oxygen supply/consumption system is an inverting transistor amplifier.
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Affiliation(s)
- Aleksander S Golub
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University , Richmond, Virginia
| | - Sami C Dodhy
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University , Richmond, Virginia
| | - Roland N Pittman
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University , Richmond, Virginia
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20
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Hirai DM, Craig JC, Colburn TD, Eshima H, Kano Y, Sexton WL, Musch TI, Poole DC. Skeletal muscle microvascular and interstitial PO2 from rest to contractions. J Physiol 2018; 596:869-883. [PMID: 29288568 DOI: 10.1113/jp275170] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 12/01/2017] [Indexed: 01/21/2023] Open
Abstract
KEY POINTS Oxygen pressure gradients across the microvascular walls are essential for oxygen diffusion from blood to tissue cells. At any given flux, the magnitude of these transmural gradients is proportional to the local resistance. The greatest resistance to oxygen transport into skeletal muscle is considered to reside in the short distance between red blood cells and myocytes. Although crucial to oxygen transport, little is known about transmural pressure gradients within skeletal muscle during contractions. We evaluated oxygen pressures within both the skeletal muscle microvascular and interstitial spaces to determine transmural gradients during the rest-contraction transient in anaesthetized rats. The significant transmural gradient observed at rest was sustained during submaximal muscle contractions. Our findings support that the blood-myocyte interface provides substantial resistance to oxygen diffusion at rest and during contractions and suggest that modulations in microvascular haemodynamics and red blood cell distribution constitute primary mechanisms driving increased transmural oxygen flux with contractions. ABSTRACT Oxygen pressure (PO2) gradients across the blood-myocyte interface are required for diffusive O2 transport, thereby supporting oxidative metabolism. The greatest resistance to O2 flux into skeletal muscle is considered to reside between the erythrocyte surface and adjacent sarcolemma, although this has not been measured during contractions. We tested the hypothesis that O2 gradients between skeletal muscle microvascular (PO2 mv ) and interstitial (PO2 is ) spaces would be present at rest and maintained or increased during contractions. PO2 mv and PO2 is were determined via phosphorescence quenching (Oxyphor probes G2 and G4, respectively) in the exposed rat spinotrapezius during the rest-contraction transient (1 Hz, 6 V; n = 8). PO2 mv was higher than PO2 is in all instances from rest (34.9 ± 6.0 versus 15.7 ± 6.4) to contractions (28.4 ± 5.3 versus 10.6 ± 5.2 mmHg, respectively) such that the mean PO2 gradient throughout the transient was 16.9 ± 6.6 mmHg (P < 0.05 for all). No differences in the amplitude of PO2 fall with contractions were observed between the microvasculature and interstitium (10.9 ± 2.3 versus 9.0 ± 3.5 mmHg, respectively; P > 0.05). However, the speed of the PO2 is fall during contractions was slower than that of PO2 mv (time constant: 12.8 ± 4.7 versus 9.0 ± 5.1 s, respectively; P < 0.05). Consistent with our hypothesis, a significant transmural gradient was sustained (but not increased) from rest to contractions. This supports that the blood-myocyte interface is the site of a substantial PO2 gradient driving O2 diffusion during metabolic transients. Based on Fick's law, elevated O2 flux with contractions must thus rely primarily on modulations in effective diffusing capacity (mainly erythrocyte haemodynamics and distribution) as the PO2 gradient is not increased.
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Affiliation(s)
- Daniel M Hirai
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Jesse C Craig
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Trenton D Colburn
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - Hiroaki Eshima
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - Yutaka Kano
- Department of Engineering Science, University of Electro-Communications, Tokyo, Japan
| | - William L Sexton
- Department of Physiology, A.T. Still University of Health Sciences, Kirksville, MO, USA
| | - Timothy I Musch
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
| | - David C Poole
- Departments of Anatomy & Physiology, Kinesiology, Kansas State University, Manhattan, KS, USA
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21
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Ferguson BS, Rogatzki MJ, Goodwin ML, Kane DA, Rightmire Z, Gladden LB. Lactate metabolism: historical context, prior misinterpretations, and current understanding. Eur J Appl Physiol 2018; 118:691-728. [PMID: 29322250 DOI: 10.1007/s00421-017-3795-6] [Citation(s) in RCA: 202] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 12/22/2017] [Indexed: 02/07/2023]
Abstract
Lactate (La-) has long been at the center of controversy in research, clinical, and athletic settings. Since its discovery in 1780, La- has often been erroneously viewed as simply a hypoxic waste product with multiple deleterious effects. Not until the 1980s, with the introduction of the cell-to-cell lactate shuttle did a paradigm shift in our understanding of the role of La- in metabolism begin. The evidence for La- as a major player in the coordination of whole-body metabolism has since grown rapidly. La- is a readily combusted fuel that is shuttled throughout the body, and it is a potent signal for angiogenesis irrespective of oxygen tension. Despite this, many fundamental discoveries about La- are still working their way into mainstream research, clinical care, and practice. The purpose of this review is to synthesize current understanding of La- metabolism via an appraisal of its robust experimental history, particularly in exercise physiology. That La- production increases during dysoxia is beyond debate, but this condition is the exception rather than the rule. Fluctuations in blood [La-] in health and disease are not typically due to low oxygen tension, a principle first demonstrated with exercise and now understood to varying degrees across disciplines. From its role in coordinating whole-body metabolism as a fuel to its role as a signaling molecule in tumors, the study of La- metabolism continues to expand and holds potential for multiple clinical applications. This review highlights La-'s central role in metabolism and amplifies our understanding of past research.
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Affiliation(s)
- Brian S Ferguson
- College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Matthew J Rogatzki
- Department of Health and Exercise Science, Appalachian State University, Boone, NC, USA
| | - Matthew L Goodwin
- Department of Orthopaedics, University of Utah, Salt Lake City, UT, USA.,Huntsman Cancer Institute, Salt Lake City, UT, USA
| | - Daniel A Kane
- Department of Human Kinetics, St. Francis Xavier University, Antigonish, Canada
| | - Zachary Rightmire
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA
| | - L Bruce Gladden
- School of Kinesiology, Auburn University, 301 Wire Road, Auburn, AL, 36849, USA.
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22
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High-Resolution FluoRespirometry and OXPHOS Protocols for Human Cells, Permeabilized Fibers from Small Biopsies of Muscle, and Isolated Mitochondria. Methods Mol Biol 2018; 1782:31-70. [PMID: 29850993 DOI: 10.1007/978-1-4939-7831-1_3] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protocols for High-Resolution FluoRespirometry of intact cells, permeabilized cells, permeabilized muscle fibers, isolated mitochondria, and tissue homogenates offer sensitive diagnostic tests of integrated mitochondrial function using standard cell culture techniques, small needle biopsies of muscle, and mitochondrial preparation methods. Multiple substrate-uncoupler-inhibitor titration (SUIT) protocols for analysis of oxidative phosphorylation (OXPHOS) improve our understanding of mitochondrial respiratory control and the pathophysiology of mitochondrial diseases. Respiratory states are defined in functional terms to account for the network of metabolic interactions in complex SUIT protocols with stepwise modulation of coupling control and electron transfer pathway states. A regulated degree of intrinsic uncoupling is a hallmark of oxidative phosphorylation, whereas pathological and toxicological dyscoupling is evaluated as a mitochondrial defect. The noncoupled state of maximum respiration is experimentally induced by titration of established uncouplers (CCCP, FCCP, DNP) to collapse the protonmotive force across the mitochondrial inner membrane and measure the electron transfer (ET) capacity (open-circuit operation of respiration). Intrinsic uncoupling and dyscoupling are evaluated as the flux control ratio between non-phosphorylating LEAK respiration (electron flow coupled to proton pumping to compensate for proton leaks) and ET capacity. If OXPHOS capacity (maximally ADP-stimulated O2 flux) is less than ET capacity, the phosphorylation pathway contributes to flux control. Physiological substrate combinations supporting the NADH and succinate pathway are required to reconstitute tricarboxylic acid cycle function. This supports maximum ET and OXPHOS capacities, due to the additive effect of multiple electron supply pathways converging at the Q-junction. ET pathways with electron entry separately through NADH (pyruvate and malate or glutamate and malate) or succinate (succinate and rotenone) restrict ET capacity and artificially enhance flux control upstream of the Q-cycle, providing diagnostic information on specific ET-pathway branches. O2 concentration is maintained above air saturation in protocols with permeabilized muscle fibers to avoid experimental O2 limitation of respiration. Standardized two-point calibration of the polarographic oxygen sensor (static sensor calibration), calibration of the sensor response time (dynamic sensor calibration), and evaluation of instrumental background O2 flux (systemic flux compensation) provide the unique experimental basis for high accuracy of quantitative results and quality control in High-Resolution FluoRespirometry.
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Place TL, Domann FE, Case AJ. Limitations of oxygen delivery to cells in culture: An underappreciated problem in basic and translational research. Free Radic Biol Med 2017; 113:311-322. [PMID: 29032224 PMCID: PMC5699948 DOI: 10.1016/j.freeradbiomed.2017.10.003] [Citation(s) in RCA: 237] [Impact Index Per Article: 33.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 10/02/2017] [Accepted: 10/04/2017] [Indexed: 01/08/2023]
Abstract
Molecular oxygen is one of the most important variables in modern cell culture systems. Fluctuations in its concentration can affect cell growth, differentiation, signaling, and free radical production. In order to maintain culture viability, experimental validity, and reproducibility, it is imperative that oxygen levels be consistently maintained within physiological "normoxic" limits. Use of the term normoxia, however, is not consistent among scientists who experiment in cell culture. It is typically used to describe the atmospheric conditions of a standard incubator, not the true microenvironment to which the cells are exposed. This error may lead to the situation where cells grown in a standard "normoxic" oxygen concentration may actually be experiencing a wide range of conditions ranging from hyperoxia to near-anoxic conditions at the cellular level. This apparent paradox is created by oxygen's sluggish rate of diffusion through aqueous medium, and the generally underappreciated effects that cell density, media volume, and barometric pressure can have on pericellular oxygen concentration in a cell culture system. This review aims to provide an overview of this phenomenon we have termed "consumptive oxygen depletion" (COD), and includes a basic review of the physics, potential consequences, and alternative culture methods currently available to help circumvent this largely unrecognized problem.
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Affiliation(s)
- Trenton L. Place
- Department of Obstetrics & Gynecology, Carver College of Medicine, The University of Iowa, Iowa City, IA
| | - Frederick E. Domann
- Department of Radiation Oncology, Carver College of Medicine, The University of Iowa, Iowa City, IA
- Department of Pathology, Carver College of Medicine, The University of Iowa, Iowa City, IA
- Department of Surgery, Carver College of Medicine, The University of Iowa, Iowa City, IA
- Corresponding authors: Department of Physiology, University of Nebraska Medical Center, Omaha, NE 68198.
| | - Adam J. Case
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE
- Corresponding authors: Department of Physiology, University of Nebraska Medical Center, Omaha, NE 68198.
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24
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Begicevic RR, Falasca M. ABC Transporters in Cancer Stem Cells: Beyond Chemoresistance. Int J Mol Sci 2017; 18:E2362. [PMID: 29117122 PMCID: PMC5713331 DOI: 10.3390/ijms18112362] [Citation(s) in RCA: 232] [Impact Index Per Article: 33.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 11/02/2017] [Accepted: 11/02/2017] [Indexed: 12/19/2022] Open
Abstract
The efficacy of chemotherapy is one of the main challenges in cancer treatment and one of the major obstacles to overcome in achieving lasting remission and a definitive cure in patients with cancer is the emergence of cancer resistance. Indeed, drug resistance is ultimately accountable for poor treatment outcomes and tumour relapse. There are various molecular mechanisms involved in multidrug resistance, such as the change in the activity of membrane transporters primarily belonging to the ATP binding cassette (ABC) transporter family. In addition, it has been proposed that this common feature could be attributed to a subpopulation of slow-cycling cancer stem cells (CSCs), endowed with enhanced tumorigenic potential and multidrug resistance. CSCs are characterized by the overexpression of specific surface markers that vary in different cancer cell types. Overexpression of ABC transporters has been reported in several cancers and more predominantly in CSCs. While the major focus on the role played by ABC transporters in cancer is polarized by their involvement in chemoresistance, emerging evidence supports a more active role of these proteins, in which they release specific bioactive molecules in the extracellular milieu. This review will outline our current understanding of the role played by ABC transporters in CSCs, how their expression is regulated and how they support the malignant metabolic phenotype. To summarize, we suggest that the increased expression of ABC transporters in CSCs may have precise functional roles and provide the opportunity to target, particularly these cells, by using specific ABC transporter inhibitors.
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Affiliation(s)
- Romana-Rea Begicevic
- Metabolic Signalling Group, School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth WA 6102, Australia.
| | - Marco Falasca
- Metabolic Signalling Group, School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth WA 6102, Australia.
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Takahashi E, Yamaoka Y. Simple and inexpensive technique for measuring oxygen consumption rate in adherent cultured cells. J Physiol Sci 2017; 67:731-737. [PMID: 28785888 PMCID: PMC10717709 DOI: 10.1007/s12576-017-0563-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/25/2017] [Indexed: 01/08/2023]
Abstract
Measurement of cellular oxygen consumption rate (OCR) is essential in assessing roles of mitochondria in physiology and pathophysiology. Classical techniques, in which polarographic oxygen electrode measures the extracellular oxygen concentration in a closed measuring vessel, require isolation and suspension of the cell. Because cell functions depend on the extracellular milieu including the extracellular matrix, isolation of cultured cells prior to the measurement may significantly affect the OCR. More recent techniques utilize optical methods in which oxygen-dependent quenching of fluorophores determines oxygen concentration in the medium at a few microns above the surface of the cultured cells. These techniques allow the OCR measurement in cultured cells adhered to the culture dish. However, this technique requires special equipment such as a fluorescence lifetime microplate reader or specialized integrated system, which are usually quite expensive. Here, we introduce a simple and inexpensive technique for measuring OCR in adherent cultured cells that utilizes conventional fluorescence microscopy and a glassware called a gap cover glass.
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Affiliation(s)
- Eiji Takahashi
- Advanced Technology Fusion, Graduate School of Science and Engineering, Saga University, Saga, 840-8502, Japan.
| | - Yoshihisa Yamaoka
- Advanced Technology Fusion, Graduate School of Science and Engineering, Saga University, Saga, 840-8502, Japan
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26
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Alves de Souza CE, Alves de Souza HDM, Stipp MC, Corso CR, Galindo CM, Cardoso CR, Dittrich RL, de Souza Ramos EA, Klassen G, Carlos RM, Correia Cadena SMS, Acco A. Ruthenium complex exerts antineoplastic effects that are mediated by oxidative stress without inducing toxicity in Walker-256 tumor-bearing rats. Free Radic Biol Med 2017. [PMID: 28629835 DOI: 10.1016/j.freeradbiomed.2017.06.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The present study evaluated the in vivo antitumor effects and toxicity of a new Ru(II) compound, cis-(Ru[phen]2[ImH]2)2+ (also called RuphenImH [RuC]), against Walker-256 carcinosarcoma in rats. After subcutaneous inoculation of Walker-256 cells in the right pelvic limb, male Wistar rats received 5 or 10mgkg-1 RuC orally or intraperitoneally (i.p.) every 3 days for 13 days. A positive control group (2mgkg-1 cisplatin) and negative control group (vehicle) were also used. Tumor progression was checked daily. After treatment, tumor weight, plasma biochemistry, hematology, oxidative stress, histology, and tumor cell respiration were evaluated. RuC was effective against tumors when administered i.p. but not orally. The highest i.p. dose of RuC (10mgkg-1) significantly reduced tumor volume and weight, induced oxidative stress in tumor tissue, reduced the respiration of tumor cells, and induced necrosis but did not induce apoptosis in the tumor. No clinical signs of toxicity or death were observed in tumor-bearing or healthy rats that were treated with RuC. These results suggest that RuC has antitumor activity through the modulation of oxidative stress and impairment of oxidative phosphorylation, thus promoting Walker-256 cell death without causing systemic toxicity. These effects make RuC a promising anticancer drug for clinical evaluation.
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Affiliation(s)
| | | | | | - Claudia Rita Corso
- Department of Pharmacology, Federal University of Parana, Curitiba, Brazil
| | | | | | | | | | - Giseli Klassen
- Department of Basic Pathology, Federal University of Parana, Curitiba, Brazil
| | - Rose Maria Carlos
- Department of Chemistry, Federal São Carlos University, São Carlos, Brazil
| | | | - Alexandra Acco
- Department of Pharmacology, Federal University of Parana, Curitiba, Brazil.
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Rodrigues-Silva E, Siqueira-Santos ES, Ruas JS, Ignarro RS, Figueira TR, Rogério F, Castilho RF. Evaluation of mitochondrial respiratory function in highly glycolytic glioma cells reveals low ADP phosphorylation in relation to oxidative capacity. J Neurooncol 2017; 133:519-529. [PMID: 28540666 DOI: 10.1007/s11060-017-2482-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 05/14/2017] [Indexed: 01/25/2023]
Abstract
High-grade gliomas are aggressive and intensely glycolytic tumors. In the present study, we evaluated the mitochondrial respiratory function of glioma cells (T98G and U-87MG) and fresh human glioblastoma (GBM) tissue. To this end, measurements of oxygen consumption rate (OCR) were performed under various experimental conditions. The OCR of T98G and U-87MG cells was well coupled to ADP phosphorylation based on the ratio of ATP produced per oxygen consumed of ~2.5. In agreement, the basal OCR of GBM tissue was also partially associated with ADP phosphorylation. The basal respiration of intact T98G and U-87MG cells was not limited by the supply of endogenous substrates, as indicated by the increased OCR in response to a protonophore. These cells also displayed a high affinity for oxygen, as evidenced by the values of the partial pressure of oxygen when respiration is half maximal (p 50). In permeabilized glioma cells, ADP-stimulated OCR was only approximately 50% of that obtained in the presence of protonophore, revealing a significant limitation in oxidative phosphorylation (OXPHOS) relative to the activity of the electron transport system (ETS). This characteristic was maintained when the cells were grown under low glucose conditions. Flux control coefficient analyses demonstrated that the impaired OXPHOS was associated with the function of both mitochondrial ATP synthase and the adenine nucleotide translocator, but not the phosphate carrier. Altogether, these data indicate that the availability and metabolism of respiratory substrates and mitochondrial ETS are preserved in T98G and U-87MG glioma cells even though these cells possess a relatively restrained OXPHOS capability.
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Affiliation(s)
- Erika Rodrigues-Silva
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, 13083-887, Brazil
| | - Edilene S Siqueira-Santos
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, 13083-887, Brazil
| | - Juliana S Ruas
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, 13083-887, Brazil
| | - Raffaela S Ignarro
- Departamento de Anatomia Patológica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Tiago R Figueira
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, 13083-887, Brazil
| | - Fábio Rogério
- Departamento de Anatomia Patológica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Roger F Castilho
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, 13083-887, Brazil.
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Abstract
PURPOSE Oxygen is essential for aerobic mammalian cell physiology. Oxygen tension (PO2) should reach a minimum at some position within the corneal stroma, and oxygen flux should be zero, by definition, at this point as well. We found the locations and magnitudes of this "corneal equilibrium flux" (xmin) and explored its physiological implications. METHODS We used an application of the Monod kinetic model to calculate xmin for normal human cornea as anterior surface PO2 changes from 155 to 20 mmHg. RESULTS We find that xmin deepens, broadens, and advances from 1.25 μm above the endothelial-aqueous humor surface toward the epithelium (reaching a position 320 μm above the endothelial-aqueous humor surface) as anterior corneal surface PO2 decreases from 155 to 20 mmHg. CONCLUSIONS Our model supports an anterior corneal oxygen flux of 9 μL O2 · cm · h and an epithelial oxygen consumption of approximately 4 μL O2 · cm · h. Only at the highest anterior corneal PO2 does our model predict that oxygen diffuses all the way through the cornea to perhaps reach the anterior chamber. Of most interest, corneal oxygen consumption should be supported down to a corneal surface PO2 of 60 to 80 mmHg but declines below this range. We conclude that the critical oxygen tension for hypoxia induced corneal swelling is more likely this range rather than a fixed value.
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Venkatachalam MA, Weinberg JM. Pericytes Preserve Capillary Integrity to Prevent Kidney Hypoxia. J Am Soc Nephrol 2016; 28:717-719. [PMID: 27979991 DOI: 10.1681/asn.2016111157] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
| | - Joel M Weinberg
- Department of Medicine, University of Michigan Medical Center, Ann Arbor, Michigan
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30
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Drehmer DL, de Aguiar AM, Brandt AP, Petiz L, Cadena SMSC, Rebelatto CK, Brofman PRS, Filipak Neto F, Dallagiovanna B, Abud APR. Metabolic switches during the first steps of adipogenic stem cells differentiation. Stem Cell Res 2016; 17:413-421. [PMID: 27653462 DOI: 10.1016/j.scr.2016.09.001] [Citation(s) in RCA: 274] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 08/30/2016] [Accepted: 09/02/2016] [Indexed: 10/21/2022] Open
Abstract
The understanding of metabolism during cell proliferation and commitment provides a greater insight into the basic biology of cells, allowing future applications. Here we evaluated the energy and oxidative changes during the early adipogenic differentiation of human adipose tissue-derived stromal cells (hASCs). hASCs were maintained under differentiation conditions during 3 and 7days. Oxygen consumption, mitochondrial mass and membrane potential, reactive oxygen species (ROS) generation, superoxide dismutase (SOD) and catalase activities, non-protein thiols (NPT) concentration and lipid peroxidation were analyzed. We observed that 7days of adipogenic induction are required to stimulate cells to consume more oxygen and increase mitochondrial activity, indicating organelle maturation and a transition from glycolytic to oxidative energy metabolism. ROS production was only increased after 3days and may be involved in the differentiation commitment. ROS source was not only the mitochondria and we suggest that NOX proteins are related to ROS generation and therefore adipogenic commitment. ROS production did not change after 7days, but an increased activity of catalase and NPT concentration as well as a decreased lipid peroxidation were observed. Thus, a short period of differentiation induction is able to change the energetic and oxidative metabolic profile of hASCs and stimulate cytoprotection processes.
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Affiliation(s)
- Daiana Leila Drehmer
- Laboratório de Biologia Básica de Células Tronco, Instituto Carlos Chagas, Fiocruz, Curitiba, Paraná, Brazil
| | - Alessandra Melo de Aguiar
- Laboratório de Biologia Básica de Células Tronco, Instituto Carlos Chagas, Fiocruz, Curitiba, Paraná, Brazil
| | | | - Lyvia Petiz
- Universidade Federal do Paraná, Paraná, Paraná, Brazil
| | | | | | - Paulo R S Brofman
- Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil
| | | | - Bruno Dallagiovanna
- Laboratório de Biologia Básica de Células Tronco, Instituto Carlos Chagas, Fiocruz, Curitiba, Paraná, Brazil
| | - Ana Paula Ressetti Abud
- Laboratório de Biologia Básica de Células Tronco, Instituto Carlos Chagas, Fiocruz, Curitiba, Paraná, Brazil.
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Schiffer TA, Peleli M, Sundqvist ML, Ekblom B, Lundberg JO, Weitzberg E, Larsen FJ. Control of human energy expenditure by cytochrome c oxidase subunit IV-2. Am J Physiol Cell Physiol 2016; 311:C452-61. [PMID: 27486093 DOI: 10.1152/ajpcell.00099.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/09/2016] [Indexed: 01/12/2023]
Abstract
Resting metabolic rate (RMR) in humans shows pronounced individual variations, but the underlying molecular mechanism remains elusive. Cytochrome c oxidase (COX) plays a key role in control of metabolic rate, and recent studies of the subunit 4 isoform 2 (COX IV-2) indicate involvement in the cellular response to hypoxia and oxidative stress. We evaluated whether the COX subunit IV isoform composition may explain the pronounced individual variations in resting metabolic rate (RMR). RMR was determined in healthy humans by indirect calorimetry and correlated to levels of COX IV-2 and COX IV-1 in vastus lateralis. Overexpression and knock down of the COX IV isoforms were performed in primary myotubes followed by evaluation of the cell respiration and production of reactive oxygen species. Here we show that COX IV-2 protein is constitutively expressed in human skeletal muscle and strongly correlated to RMR. Primary human myotubes overexpressing COX IV-2 displayed markedly (>60%) lower respiration, reduced (>50%) cellular H2O2 production, higher resistance toward both oxidative stress, and severe hypoxia compared with control cells. These results suggest an important role of isoform COX IV-2 in the control of energy expenditure, hypoxic tolerance, and mitochondrial ROS homeostasis in humans.
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Affiliation(s)
- Tomas A Schiffer
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Maria Peleli
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Michaela L Sundqvist
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Björn Ekblom
- Åstrand Laboratory of Work Physiology, Swedish School of Sport and Health Sciences, Stockholm, Sweden; and
| | - Jon O Lundberg
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Eddie Weitzberg
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; Department of Anesthesia & Intensive Care, Karolinska University Hospital, Stockholm, Sweden
| | - Filip J Larsen
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; Åstrand Laboratory of Work Physiology, Swedish School of Sport and Health Sciences, Stockholm, Sweden; and
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Brandt AP, Gozzi GJ, Pires ADRA, Martinez GR, Dos Santos Canuto AV, Echevarria A, Di Pietro A, Cadena SMSC. Impairment of oxidative phosphorylation increases the toxicity of SYD-1 on hepatocarcinoma cells (HepG2). Chem Biol Interact 2016; 256:154-60. [PMID: 27417255 DOI: 10.1016/j.cbi.2016.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/22/2016] [Accepted: 07/07/2016] [Indexed: 12/11/2022]
Abstract
Toxicity of the SYD-1 mesoionic compound (3-[4-chloro-3-nitrophenyl]-1,2,3-oxadiazolium-5-olate) was evaluated on human liver cancer cells (HepG2) grown in either high glucose (HG) or galactose (GAL) medium, and also on suspended cells kept in HG medium. SYD-1 was able to decrease the viability of cultured HepG2 cells in a dose-dependent manner, as assessed by MTT, LDH release and dye with crystal violet assays, but no effect was observed on suspended cells after 1-40 min of treatment. Respiration analysis was performed after 2 min (suspended cells) or 24 h (cultured cells) of treatment: no change was observed in suspended cells, whereas SYD-1 inhibited as well basal, leak and uncoupled states of the respiration in cultured cells with HG medium. These inhibitions were consistent with the decrease in pyruvate level and increase in lactate level. Even more extended results were obtained with HepG2 cells grown in GAL medium where, additionally, the ATP amount was reduced. Furthermore, SYD-1 appears not to be transported by the main ABC multidrug transporters. These results show that SYD-1 is able to change the metabolism of HepG2 cells, and suggest that its cytotoxicity is related to impairment of mitochondrial metabolism. Therefore, we may propose that SYD-1 is a potential candidate for hepatocarcinoma treatment.
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Affiliation(s)
- Anna Paula Brandt
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - Gustavo Jabor Gozzi
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | | | - Glaucia Regina Martinez
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | | | - Aurea Echevarria
- Departamento de Química, Universidade Federal Rural do Rio de Janeiro, Rio de Janeiro, Brazil
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Abstract
For decades, tumor cells have been considered defective in mitochondrial respiration due to their dominant glycolytic metabolism. However, a growing body of evidence is now challenging this assumption, and also implying that tumors are metabolically less homogeneous than previously supposed. A small subpopulation of slow-cycling cells endowed with tumorigenic potential and multidrug resistance has been isolated from different tumors. Deep metabolic characterization of these tumorigenic cells revealed their dependency on mitochondrial respiration versus glycolysis, suggesting the existence of a common metabolic program active in slow-cycling cells across different tumors. These findings change our understanding of tumor metabolism and also highlight new vulnerabilities that can be exploited to eradicate cancer cells responsible for tumor relapse.
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Langley R, Cunningham S. How Should Oxygen Supplementation Be Guided by Pulse Oximetry in Children: Do We Know the Level? Front Pediatr 2016; 4:138. [PMID: 28191454 PMCID: PMC5269450 DOI: 10.3389/fped.2016.00138] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 12/08/2016] [Indexed: 11/13/2022] Open
Abstract
Supplemental oxygen is one of the most commonly prescribed therapies to children in hospital, but one of the least studied therapeutics. This review considers oxygen from a range of perspectives; discovery and early use; estimation of oxygenation in the human body-both clinically and by medical device; the effects of illness on oxygen utilization; the cellular consequences of low oxygen; and finally, how clinical studies currently inform our approach to targeting supplementing oxygen in those with lower than normal oxygen saturation.
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Affiliation(s)
- Ross Langley
- Department of Respiratory and Sleep Medicine, Royal Hospital for Sick Children , Edinburgh , UK
| | - Steve Cunningham
- Department of Respiratory and Sleep Medicine, Royal Hospital for Sick Children , Edinburgh , UK
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Abstract
A major barrier to achieving durable remission and a definitive cure in oncology patients is the emergence of tumor resistance, a common outcome of different disease types, and independent from the therapeutic approach undertaken. In recent years, subpopulations of slow-cycling cells endowed with enhanced tumorigenic potential and multidrug resistance have been isolated in different tumors, and mounting experimental evidence suggests these resistant cells are responsible for tumor relapse. An in-depth metabolic characterization of resistant tumor stem cells revealed that they rely more on mitochondrial respiration and less on glycolysis than other tumor cells, a finding that challenges the assumption that tumors have a primarily glycolytic metabolism and defective mitochondria. The demonstration of a metabolic program in resistant tumorigenic cells that may be present in the majority of tumors has important therapeutic implications and is a critical consideration as we address the challenge of identifying new vulnerabilities that might be exploited therapeutically.
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Affiliation(s)
- Andrea Viale
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA.
| | - Giulio F Draetta
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
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Zhdanov AV, Golubeva AV, Okkelman IA, Cryan JF, Papkovsky DB. Imaging of oxygen gradients in giant umbrella cells: an ex vivo PLIM study. Am J Physiol Cell Physiol 2015; 309:C501-9. [DOI: 10.1152/ajpcell.00121.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/03/2015] [Indexed: 12/29/2022]
Abstract
O2 plays a pivotal role in aerobic metabolism and regulation of cell and tissue function. Local differences and fluctuations in tissue O2 levels are well documented; however, the physiological significance of O2 microgradients, particularly at the subcellular level, remains poorly understood. Using the cell-penetrating phosphorescent O2 probe Pt-Glc and confocal fluorescence microscopy, we visualized O2 distribution in individual giant (>100-μm) umbrella cells located superficially in the urinary bladder epithelium. We optimized conditions for in vivo phosphorescent staining of the inner surface of the mouse bladder and subsequent ex vivo analysis of excised live tissue. Imaging experiments revealed significant (≤85 μM) and heterogeneous deoxygenation within respiring umbrella cells, with radial O2 gradients of up to 40 μM across the cell, or ∼0.6 μM/μm. Deeply deoxygenated (5–15 μM O2) regions were seen to correspond to the areas enriched with polarized mitochondria. Pharmacological activation of mitochondrial respiration decreased oxygenation and O2 gradients in umbrella cells, while inhibition with antimycin A dissipated the gradients and caused gradual reoxygenation of the tissue to ambient levels. Detailed three-dimensional maps of O2 distribution potentially can be used for the modeling of intracellular O2-dependent enzymatic reactions and downstream processes, such as hypoxia-inducible factor signaling. Further ex vivo and in vivo studies on intracellular and tissue O2 gradients using confocal imaging can shed light on the molecular mechanisms regulating O2-dependent (patho)physiological processes in the bladder and other tissues.
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Affiliation(s)
- A. V. Zhdanov
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - A. V. Golubeva
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland; and
| | - I. A. Okkelman
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
| | - J. F. Cryan
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland; and
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - D. B. Papkovsky
- School of Biochemistry and Cell Biology, University College Cork, Cork, Ireland
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Harrison DK, Fasching M, Fontana-Ayoub M, Gnaiger E. Cytochrome redox states and respiratory control in mouse and beef heart mitochondria at steady-state levels of hypoxia. J Appl Physiol (1985) 2015; 119:1210-8. [PMID: 26251509 DOI: 10.1152/japplphysiol.00146.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 08/03/2015] [Indexed: 11/22/2022] Open
Abstract
Mitochondrial control of cellular redox states is a fundamental component of cell signaling in the coordination of core energy metabolism and homeostasis during normoxia and hypoxia. We investigated the relationship between cytochrome redox states and mitochondrial oxygen consumption at steady-state levels of hypoxia in mitochondria isolated from beef and mouse heart (BHImt, MHImt), comparing two species with different cardiac dynamics and local oxygen demands. A low-noise, rapid spectrophotometric system using visible light for the measurement of cytochrome redox states was combined with high-resolution respirometry. Monophasic hyperbolic relationships were observed between oxygen consumption, JO2, and oxygen partial pressure, Po2, within the range <1.1 kPa (8.3 mmHg; 13 μM). P50j (Po2 at 0.5·Jmax) was 0.015 ± 0.0004 and 0.021 ± 0.003 kPa (0.11 and 0.16 mmHg) for BHImt and MHImt, respectively. Maximum oxygen consumption, Jmax, was measured at saturating ADP levels (OXPHOS capacity) with Complex I-linked substrate supply. Redox states of cytochromes aa3 and c were biphasic hyperbolic functions of Po2. The relationship between cytochrome oxidation state and oxygen consumption revealed a separation of distinct phases from mild to severe and deep hypoxia. When cytochrome c oxidation increased from fully reduced to 45% oxidized at 0.1 Jmax, Po2 was as low as 0.002 kPa (0.02 μM), and trace amounts of oxygen are sufficient to partially oxidize the cytochromes. At higher Po2 under severe hypoxia, respiration increases steeply, whereas redox changes are small. Under mild hypoxia, the steep slope of oxidation of cytochrome c when flux remains more stable represents a cushioning mechanism that helps to maintain respiration high at the onset of hypoxia.
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Affiliation(s)
- David K Harrison
- OROBOROS INSTRUMENTS, Innsbruck, Austria; Microvascular Measurements, St Lorenzen, Italy; and
| | | | | | - Erich Gnaiger
- OROBOROS INSTRUMENTS, Innsbruck, Austria; D Swarowski Research Laboratory, Department of Visceral Transplant and Thoracic Surgery, Medical University of Innsbruck, Austria
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38
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Seymour RS, Ito K, Umekawa Y, Matthews PDG, Pirintsos SA. The oxygen supply to thermogenic flowers. PLANT, CELL & ENVIRONMENT 2015; 38:827-837. [PMID: 25256124 DOI: 10.1111/pce.12454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 09/15/2014] [Accepted: 09/17/2014] [Indexed: 06/03/2023]
Abstract
Thermogenic flowers produce heat by intense respiration, and the rates of O2 consumption (Ṁo2) in some species can exceed those of all other tissues of plants and most animals. By exposing intact flowers to a range of O2 pressures (Po2) and measuring Ṁo2, we demonstrate that the highest respiration rates exceed the capacity of the O2 diffusive pathway and become diffusion limited in atmospheric air. The male florets on the inflorescence of Arum concinnatum have the highest known mass-specific Ṁo2 and can be severely diffusion limited. Intact spadices of Japanese skunk cabbage Symplocarpus renifolius are diffusion limited in air only when Ṁo2 is maximal, but not at lower levels. True flowers of the sacred lotus Nelumbo nucifera and the appendix of Arum concinnatum are never diffusion limited in air. Ṁo2 - Po2 curves are evaluated quantitatively with the 'Regulation Index', a new tool to measure dependence of Ṁo2 on ambient Po2 , as well as the conventional 'Critical Po2 '. The study also includes measurements of Po2 within thermogenic tissues with O2-sensitive fibre optics, and reveals that the diffusion pathway is complicated and that O2 can be provided not only from the surface of the tissues but also from the pith of the flower's peduncle.
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Affiliation(s)
- Roger S Seymour
- School of Biological Sciences, University of Adelaide, Adelaide, South Australia, 5005, Australia
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Abstract
Evidence is presented that the rate and equilibrium constants in mitochondrial oxidative phosphorylation set and maintain metabolic homeostasis in eukaryotic cells. These internal constants determine the energy state ([ATP]/[ADP][Pi]), and the energy state maintains homeostasis through a bidirectional sensory/signaling control network that reaches every aspect of cellular metabolism. The energy state is maintained with high precision (to ∼1 part in 10(10)), and the control system can respond to transient changes in energy demand (ATP utilization) of more than 100 times the resting rate. Epigenetic and environmental factors are able to "fine-tune" the programmed set point over a narrow range to meet the special needs associated with cell differentiation and chronic changes in metabolic requirements. The result is robust across-platform control of metabolism, which is essential to cellular differentiation and the evolution of complex organisms. A model of oxidative phosphorylation is presented, for which the steady-state rate expression has been derived and computer programmed. The behavior of oxidative phosphorylation predicted by the model is shown to fit the experimental data available for isolated mitochondria as well as for cells and tissues. This includes measurements from several different mammalian tissues as well as from insect flight muscle and plants. The respiratory chain and oxidative phosphorylation is remarkably similar for all higher plants and animals. This is consistent with the efficient synthesis of ATP and precise control of metabolic homeostasis provided by oxidative phosphorylation being a key to cellular differentiation and the evolution of structures with specialized function.
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Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Cano I, Roca J, Wagner PD. Effects of lung ventilation-perfusion and muscle metabolism-perfusion heterogeneities on maximal O2 transport and utilization. J Physiol 2015; 593:1841-56. [PMID: 25640017 DOI: 10.1113/jphysiol.2014.286492] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/27/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS We expanded a prior model of whole-body O2 transport and utilization based on diffusive O2 exchange in the lungs and tissues to additionally allow for both lung ventilation-perfusion and tissue metabolism-perfusion heterogeneities, in order to estimate V̇O2 and mitochondrial PO2 (PmO2) during maximal exercise. Simulations were performed using data from (a) healthy fit subjects exercising at sea level and at altitudes up to the equivalent of Mount Everest and (b) patients with mild and severe chronic obstructive pulmonary disease (COPD) exercising at sea level. Heterogeneity in skeletal muscle may affect maximal O2 availability more than heterogeneity in lung, especially if mitochondrial metabolic capacity (V̇ MAX ) is only slightly higher than the potential to deliver O2 , but when V̇ MAX is substantially higher than O2 delivery, the effect of muscle heterogeneity is comparable to that of lung heterogeneity. Skeletal muscle heterogeneity may result in a wide range of potential mitochondrial PO 2 values, a range that becomes narrower as V̇ MAX increases; in regions with a low ratio of metabolic capacity to blood flow, PmO2 can exceed that of mixed muscle venous blood. The combined effects of lung and peripheral heterogeneities on the resistance to O2 flow in health decreases with altitude. ABSTRACT Previous models of O2 transport and utilization in health considered diffusive exchange of O2 in lung and muscle, but, reasonably, neglected functional heterogeneities in these tissues. However, in disease, disregarding such heterogeneities would not be justified. Here, pulmonary ventilation-perfusion and skeletal muscle metabolism-perfusion mismatching were added to a prior model of only diffusive exchange. Previously ignored O2 exchange in non-exercising tissues was also included. We simulated maximal exercise in (a) healthy subjects at sea level and altitude, and (b) COPD patients at sea level, to assess the separate and combined effects of pulmonary and peripheral functional heterogeneities on overall muscle O2 uptake (V̇O2) and on mitochondrial PO2 (PmO2). In healthy subjects at maximal exercise, the combined effects of pulmonary and peripheral heterogeneities reduced arterial PO2 (PaO2) at sea level by 32 mmHg, but muscle V̇O2 by only 122 ml min(-1) (-3.5%). At the altitude of Mt Everest, lung and tissue heterogeneity together reduced PaO2 by less than 1 mmHg and V̇O2 by 32 ml min(-1) (-2.4%). Skeletal muscle heterogeneity led to a wide range of potential PmO2 among muscle regions, a range that becomes narrower asV̇ MAX increases, and in regions with a low ratio of metabolic capacity to blood flow, PmO2 can exceed that of mixed muscle venous blood. For patients with severe COPD, peak V̇O2 was insensitive to substantial changes in the mitochondrial characteristics for O2 consumption or the extent of muscle heterogeneity. This integrative computational model of O2 transport and utilization offers the potential for estimating profiles of PmO2 both in health and in diseases such as COPD if the extent for both lung ventilation-perfusion and tissue metabolism-perfusion heterogeneity is known.
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Affiliation(s)
- I Cano
- Hospital Clinic, IDIBAPS, CIBERES, Universitat de Barcelona, Barcelona, Catalunya, Spain; Centro de Investigación en Red de Enfermedades Respiratorias (CibeRes), Palma de Mallorca, Spain
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Xu XD, Shao SX, Jiang HP, Cao YW, Wang YH, Yang XC, Wang YL, Wang XS, Niu HT. Warburg effect or reverse Warburg effect? A review of cancer metabolism. Oncol Res Treat 2015; 38:117-22. [PMID: 25792083 DOI: 10.1159/000375435] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/22/2015] [Indexed: 11/19/2022]
Abstract
Cancer is a major threat to human health. A considerable amount of research has focused on elucidating the nature of cancer from its pathogenesis to treatment and prevention. Tumor cell metabolism has been considered a hallmark of cancer. Cancer cells differ from normal cells through unlimited cell division, and show a greater need for energy for their rapid growth and duplication. Research on glycometabolism, as the key point of energy metabolism, has played a unique role. In the 1920s, Warburg found that cancer cells prefer to produce adenosine triphosphate (ATP) by glycolysis, which is a less efficient pathway compared to oxidative phosphorylation. This striking discovery, called 'the Warburg effect', has influenced and guided the study of the mechanism and treatment of tumors for generations, but its causal relationship with cancer progression is still unclear. Some studies have now shown contradicting evidence and a new hypothesis, the reverse Warburg effect, has been put forward, in which cancer cells produce most of their ATP via glycolysis, even under aerobic conditions. In this review we discuss the new points concerning the energy metabolism of a tumor, as well as the current facts and perspectives.
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Affiliation(s)
- Xiao Dong Xu
- The Key Laboratory of Urology, Department of Urology, The Affiliated Hospital of Qingdao University, Qingdao, China
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D'Aprile A, Scrima R, Quarato G, Tataranni T, Falzetti F, Di Ianni M, Gemei M, Del Vecchio L, Piccoli C, Capitanio N. Hematopoietic stem/progenitor cells express myoglobin and neuroglobin: adaptation to hypoxia or prevention from oxidative stress? Stem Cells 2014; 32:1267-77. [PMID: 24446190 DOI: 10.1002/stem.1646] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 12/25/2013] [Indexed: 12/22/2022]
Abstract
Oxidative metabolism and redox signaling prove to play a decisional role in controlling adult hematopoietic stem/progenitor cells (HSPCs) biology. However, HSPCs reside in a hypoxic bone marrow microenvironment raising the question of how oxygen metabolism might be ensued. In this study, we provide for the first time novel functional and molecular evidences that human HSPCs express myoglobin (Mb) at level comparable with that of a muscle-derived cell line. Optical spectroscopy and oxymetry enabled to estimate an O2-sensitive heme-containing protein content of approximately 180 ng globin per 10(6) HSPC and a P50 of approximately 3 µM O2. Noticeably, expression of Mb mainly occurs through a HIF-1-induced alternative transcript (Mb-V/Mb-N = 35 ± 15, p < .01). A search for other Mb-related globins unveiled significant expression of neuroglobin (Ngb) but not of cytoglobin. Confocal microscopy immune detection of Mb in HSPCs strikingly revealed nuclear localization in cell subsets expressing high level of CD34 (nuclear/cytoplasmic Mb ratios 1.40 ± 0.02 vs. 0.85 ± 0.05, p < .01) whereas Ngb was homogeneously distributed in all the HSPC population. Dual-color fluorescence flow cytometry indicated that while the Mb content was homogeneously distributed in all the HSPC subsets that of Ngb was twofold higher in more immature HSPC. Moreover, we show that HSPCs exhibit a hypoxic nitrite reductase activity releasing NO consistent with described noncanonical functions of globins. Our finding extends the notion that Mb and Ngb can be expressed in nonmuscle and non-neural contexts, respectively, and is suggestive of a differential role of Mb in HSPC in controlling oxidative metabolism at different stages of commitment.
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Affiliation(s)
- Annamaria D'Aprile
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
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Cano I, Selivanov V, Gomez-Cabrero D, Tegnér J, Roca J, Wagner PD, Cascante M. Oxygen pathway modeling estimates high reactive oxygen species production above the highest permanent human habitation. PLoS One 2014; 9:e111068. [PMID: 25375931 PMCID: PMC4222897 DOI: 10.1371/journal.pone.0111068] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 09/19/2014] [Indexed: 11/19/2022] Open
Abstract
The production of reactive oxygen species (ROS) from the inner mitochondrial membrane is one of many fundamental processes governing the balance between health and disease. It is well known that ROS are necessary signaling molecules in gene expression, yet when expressed at high levels, ROS may cause oxidative stress and cell damage. Both hypoxia and hyperoxia may alter ROS production by changing mitochondrial Po2 (PmO2). Because PmO2 depends on the balance between O2 transport and utilization, we formulated an integrative mathematical model of O2 transport and utilization in skeletal muscle to predict conditions to cause abnormally high ROS generation. Simulations using data from healthy subjects during maximal exercise at sea level reveal little mitochondrial ROS production. However, altitude triggers high mitochondrial ROS production in muscle regions with high metabolic capacity but limited O2 delivery. This altitude roughly coincides with the highest location of permanent human habitation. Above 25,000 ft., more than 90% of exercising muscle is predicted to produce abnormally high levels of ROS, corresponding to the "death zone" in mountaineering.
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Affiliation(s)
- Isaac Cano
- Center for respiratory diagnoses, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and Centro de Investigación Biomédica en Red en Enfermedades Respiratorias (CIBERES) and Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Vitaly Selivanov
- Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona and Institute of Biomedicine (IBUB), Barcelona, Catalonia, Spain
| | - David Gomez-Cabrero
- Unit of Computational Medicine of the Center for Molecular Medicine, Karolinska Institutet and Karoliska University Hospital - Department of Medicine, Stockholm, Sweden
| | - Jesper Tegnér
- Unit of Computational Medicine of the Center for Molecular Medicine, Karolinska Institutet and Karoliska University Hospital - Department of Medicine, Stockholm, Sweden
| | - Josep Roca
- Center for respiratory diagnoses, Hospital Clinic and Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and Centro de Investigación Biomédica en Red en Enfermedades Respiratorias (CIBERES) and Universitat de Barcelona, Barcelona, Catalonia, Spain
| | - Peter D. Wagner
- Division of Physiology, Pulmonary and Critical Care Medicine, University of California San Diego, San Diego, California, United States of America
| | - Marta Cascante
- Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona and Institute of Biomedicine (IBUB), Barcelona, Catalonia, Spain
- * E-mail:
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Wilson DF, Vinogradov SA. Mitochondrial cytochrome c oxidase: mechanism of action and role in regulating oxidative phosphorylation. J Appl Physiol (1985) 2014; 117:1431-9. [PMID: 25324518 DOI: 10.1152/japplphysiol.00737.2014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Mitochondrial oxidative phosphorylation has a central role in eukaryotic metabolism, providing the energy (ATP) required for survival. Regulation of this important pathway is, however, still not understood, largely due to limitations in the ability to measure the essential metabolites, including oxygen (pO2, oxygen pressure), ADP, and AMP. In addition, neither the mechanism of oxygen reduction by mitochondrial cytochrome c oxidase nor how its rate is controlled is understood, although this enzyme determines the rate of oxygen consumption and thereby the rate of ATP synthesis. Cytochrome c oxidase is responsible for reduction of molecular oxygen to water using reducing equivalents donated by cytochrome c and for site 3 energy coupling in oxidative phosphorylation. A mechanism-based model of the cytochrome c oxidase reaction is presented in which transfer of reducing equivalents from the lower- to the higher-potential region of the coupling site occurs against an opposing energy barrier, Q. The steady-state rate equation is fitted to data for the dependence of mitochondrial respiratory rate on cytochrome c reduction, oxygen pressure (pO2), and [ATP]/[ADP][Pi] at pH 6.5 to 8.35 (where Pi is inorganic phosphate). The fit of the rate expression to the experimental data is very good for all experimental conditions. Levels of the intermediates in oxygen reduction in the oxidase reaction site have been calculated. An intermediate in the reaction, tentatively identified as peroxide, bridged between the iron and copper atoms of the reaction site has a central role in coupling mitochondrial respiration to the [ATP]/[ADP][Pi].
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Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sergei A Vinogradov
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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Wilson DF, Harrison DK, Vinogradov A. Mitochondrial cytochrome c oxidase and control of energy metabolism: measurements in suspensions of isolated mitochondria. J Appl Physiol (1985) 2014; 117:1424-30. [PMID: 25324517 DOI: 10.1152/japplphysiol.00736.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Cytochrome c oxidase is the enzyme responsible for oxygen consumption by mitochondrial oxidative phosphorylation and coupling site 3 of oxidative phosphorylation. In this role it determines the cellular rate of ATP synthesis by oxidative phosphorylation and is the key to understanding how energy metabolism is regulated. Four electrons are required for the reduction of oxygen to water, and these are provided by the one-electron donor, cytochrome c. The rate of oxygen consumption (ATP synthesis) is dependent on the fraction of cytochrome c reduced (fred), oxygen pressure (pO2), energy state ([ATP]/[ADP][Pi]), and pH. In coupled mitochondria (high energy state) and pO2 >60 torr, the rate increases in an exponential-like fashion with increasing fred. When the dependence on fred is fitted to the equation rate = A: (fred)(b), A: decreased from 100 to near 20, and B: increased from 1.3 to 4 as the pH of the medium increased from 6.5 to 8.3. During oxygen depletion from the medium fred progressively increases and the rate of respiration decreases. The respiratory rate falls to ½ (P50) by about 1.5 torr, at which point fred is substantially increased. The metabolically relevant dependence on pO2 is obtained by correcting for the increase in fred, in which case the P50 is 12 torr. Adding an uncoupler of oxidative phosphorylation eliminates the dependence of the cytochrome c oxidase activity on pH and energy state. The respiratory rate becomes proportional to fred and the P50 decreases to less than 1 torr.
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Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;
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46
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Sydnone SYD-1 affects the metabolic functions of isolated rat hepatocytes. Chem Biol Interact 2014; 218:107-14. [DOI: 10.1016/j.cbi.2014.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/03/2014] [Accepted: 05/05/2014] [Indexed: 01/10/2023]
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Golub AS, Pittman RN. Bang-bang model for regulation of local blood flow. Microcirculation 2014; 20:455-83. [PMID: 23441827 DOI: 10.1111/micc.12051] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 02/19/2013] [Indexed: 11/27/2022]
Abstract
The classical model of metabolic regulation of blood flow in muscle tissue implies the maintenance of basal tone in arterioles of resting muscle and their dilation in response to exercise and/or tissue hypoxia via the evoked production of vasodilator metabolites by myocytes. A century-long effort to identify specific metabolites responsible for explaining active and reactive hyperemia has not been successful. Furthermore, the metabolic theory is not compatible with new knowledge on the role of physiological radicals (e.g., nitric oxide, NO, and superoxide anion, O2 (-) ) in the regulation of microvascular tone. We propose a model of regulation in which muscle contraction and active hyperemia are considered the physiologically normal state. We employ the "bang-bang" or "on/off" regulatory model which makes use of a threshold and hysteresis; a float valve to control the water level in a tank is a common example of this type of regulation. Active bang-bang regulation comes into effect when the supply of oxygen and glucose exceeds the demand, leading to activation of membrane NADPH oxidase, release of O2 (-) into the interstitial space and subsequent neutralization of the interstitial NO. Switching arterioles on/off when local blood flow crosses the threshold is realized by a local cell circuit with the properties of a bang-bang controller, determined by its threshold, hysteresis, and dead-band. This model provides a clear and unambiguous interpretation of the mechanism to balance tissue demand with a sufficient supply of nutrients and oxygen.
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Affiliation(s)
- Aleksander S Golub
- Department of Physiology and Biophysics, Medical College of Virginia Campus, Virginia Commonwealth University, Richmond, VA, USA.
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48
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Moreno-Sánchez R, Marín-Hernández A, Saavedra E, Pardo JP, Ralph SJ, Rodríguez-Enríquez S. Who controls the ATP supply in cancer cells? Biochemistry lessons to understand cancer energy metabolism. Int J Biochem Cell Biol 2014; 50:10-23. [PMID: 24513530 DOI: 10.1016/j.biocel.2014.01.025] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 01/21/2014] [Accepted: 01/26/2014] [Indexed: 11/17/2022]
Abstract
Applying basic biochemical principles, this review analyzes data that contrasts with the Warburg hypothesis that glycolysis is the exclusive ATP provider in cancer cells. Although disregarded for many years, there is increasing experimental evidence demonstrating that oxidative phosphorylation (OxPhos) makes a significant contribution to ATP supply in many cancer cell types and under a variety of conditions. Substrates oxidized by normal mitochondria such as amino acids and fatty acids are also avidly consumed by cancer cells. In this regard, the proposal that cancer cells metabolize glutamine for anabolic purposes without the need for a functional respiratory chain and OxPhos is analyzed considering thermodynamic and kinetic aspects for the reductive carboxylation of 2-oxoglutarate catalyzed by isocitrate dehydrogenase. In addition, metabolic control analysis (MCA) studies applied to energy metabolism of cancer cells are reevaluated. Regardless of the experimental/environmental conditions and the rate of lactate production, the flux-control of cancer glycolysis is robust in the sense that it involves the same steps: glucose transport, hexokinase, hexosephosphate isomerase and glycogen degradation, all at the beginning of the pathway; these steps together with phosphofructokinase 1 also control glycolysis in normal cells. The respiratory chain complexes exert significantly higher flux-control on OxPhos in cancer cells than in normal cells. Thus, determination of the contribution of each pathway to ATP supply and/or the flux-control distribution of both pathways in cancer cells is necessary in order to identify differences from normal cells which may lead to the design of rational alternative therapies that selectively target cancer energy metabolism.
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Affiliation(s)
- Rafael Moreno-Sánchez
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México D.F., Mexico.
| | - Alvaro Marín-Hernández
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México D.F., Mexico
| | - Emma Saavedra
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México D.F., Mexico
| | - Juan P Pardo
- Universidad Nacional Autónoma de México, Facultad de Medicina, Departamento de Bioquímica, México D.F., Mexico
| | - Stephen J Ralph
- School of Medical Sciences, Griffith University, Gold Coast Campus, Qld, Australia
| | - Sara Rodríguez-Enríquez
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Tlalpan, México D.F., Mexico; Instituto Nacional de Cancerología, Laboratorio de Medicina Translacional, Tlalpan, México D.F., Mexico
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49
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Piccoli C, Agriesti F, Scrima R, Falzetti F, Di Ianni M, Capitanio N. To breathe or not to breathe: the haematopoietic stem/progenitor cells dilemma. Br J Pharmacol 2014; 169:1652-71. [PMID: 23714011 DOI: 10.1111/bph.12253] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Revised: 05/11/2013] [Accepted: 05/16/2013] [Indexed: 12/13/2022] Open
Abstract
UNLABELLED Adult haematopoietic stem/progenitor cells (HSPCs) constitute the lifespan reserve for the generation of all the cellular lineages in the blood. Although massive progress in identifying the cluster of master genes controlling self-renewal and multipotency has been achieved in the past decade, some aspects of the physiology of HSPCs still need to be clarified. In particular, there is growing interest in the metabolic profile of HSPCs in view of their emerging role as determinants of cell fate. Indeed, stem cells and progenitors have distinct metabolic profiles, and the transition from stem to progenitor cell corresponds to a critical metabolic change, from glycolysis to oxidative phosphorylation. In this review, we summarize evidence, reported in the literature and provided by our group, highlighting the peculiar ability of HSPCs to adapt their mitochondrial oxidative/bioenergetic metabolism to survive in the hypoxic microenvironment of the endoblastic niche and to exploit redox signalling in controlling the balance between quiescence versus active cycling and differentiation. Especial prominence is given to the interplay between hypoxia inducible factor-1, globins and NADPH oxidases in managing the mitochondrial dioxygen-related metabolism and biogenesis in HSPCs under different ambient conditions. A mechanistic model is proposed whereby 'mitochondrial differentiation' is a prerequisite in uncommitted stem cells, paving the way for growth/differentiation factor-dependent processes. Advancing the understanding of stem cell metabolism will, hopefully, help to (i) improve efforts to maintain, expand and manipulate HSPCs ex vivo and realize their potential therapeutic benefits in regenerative medicine; (ii) reprogramme somatic cells to generate stem cells; and (iii) eliminate, selectively, malignant stem cells. LINKED ARTICLES This article is part of a themed section on Emerging Therapeutic Aspects in Oncology. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2013.169.issue-8.
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Affiliation(s)
- C Piccoli
- Department of Medical and Experimental Medicine, University of Foggia, Foggia, Italy.
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50
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Clanton TL, Hogan MC, Gladden LB. Regulation of cellular gas exchange, oxygen sensing, and metabolic control. Compr Physiol 2013; 3:1135-90. [PMID: 23897683 DOI: 10.1002/cphy.c120030] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cells must continuously monitor and couple their metabolic requirements for ATP utilization with their ability to take up O2 for mitochondrial respiration. When O2 uptake and delivery move out of homeostasis, cells have elaborate and diverse sensing and response systems to compensate. In this review, we explore the biophysics of O2 and gas diffusion in the cell, how intracellular O2 is regulated, how intracellular O2 levels are sensed and how sensing systems impact mitochondrial respiration and shifts in metabolic pathways. Particular attention is paid to how O2 affects the redox state of the cell, as well as the NO, H2S, and CO concentrations. We also explore how these agents can affect various aspects of gas exchange and activate acute signaling pathways that promote survival. Two kinds of challenges to gas exchange are also discussed in detail: when insufficient O2 is available for respiration (hypoxia) and when metabolic requirements test the limits of gas exchange (exercising skeletal muscle). This review also focuses on responses to acute hypoxia in the context of the original "unifying theory of hypoxia tolerance" as expressed by Hochachka and colleagues. It includes discourse on the regulation of mitochondrial electron transport, metabolic suppression, shifts in metabolic pathways, and recruitment of cell survival pathways preventing collapse of membrane potential and nuclear apoptosis. Regarding exercise, the issues discussed relate to the O2 sensitivity of metabolic rate, O2 kinetics in exercise, and influences of available O2 on glycolysis and lactate production.
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Affiliation(s)
- T L Clanton
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida, USA.
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