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Yoval-Sánchez B, Calleja LF, de la Luz Hernández-Esquivel M, Rodríguez-Zavala JS. Piperlonguminine a new mitochondrial aldehyde dehydrogenase activator protects the heart from ischemia/reperfusion injury. Biochim Biophys Acta Gen Subj 2020; 1864:129684. [PMID: 32679250 DOI: 10.1016/j.bbagen.2020.129684] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 07/01/2020] [Accepted: 07/09/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND Detoxification of aldehydes by aldehyde dehydrogenases (ALDHs) is crucial to maintain cell function. In cardiovascular diseases, reactive oxygen species generated during ischemia/reperfusion events trigger lipoperoxidation, promoting cell accumulation of highly toxic lipid aldehydes compromising cardiac function. In this context, activation of ALDH2, may contribute to preservation of cell integrity by diminishing aldehydes content more efficiently. METHODS The theoretic interaction of piperlonguminine (PPLG) with ALDH2 was evaluated by docking analysis. Recombinant human ALDH2 was used to evaluate the effects of PPLG on the kinetics of the enzyme. The effects of PPLG were further investigated in a myocardial infarction model in rats, evaluating ALDHs activity, antioxidant enzymes, oxidative stress markers and mitochondrial function. RESULTS PPLG increased the activity of recombinant human ALDH2 and protected the enzyme from inactivation by lipid aldehydes. Additionally, administration of this drug prevented the damage induced by ischemia/reperfusion in rats, restoring heart rate and blood pressure, which correlated with protection of ALDHs activity in the tissue, a lower content of lipid aldehydes, and the preservation of mitochondrial function. CONCLUSION Activation of ALDH2 by piperlonguminine ameliorates cell damage generated in heart ischemia/reperfusion events, by decreasing lipid aldehydes concentration promoting cardioprotection.
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Affiliation(s)
- Belem Yoval-Sánchez
- Departamento de Bioquímica, Instituto Nacional de Cardiología "Ignacio Chávez", Ciudad de México, 14080, México
| | - Luis Francisco Calleja
- Departamento de Bioquímica, Instituto Nacional de Cardiología "Ignacio Chávez", Ciudad de México, 14080, México
| | | | - José Salud Rodríguez-Zavala
- Departamento de Bioquímica, Instituto Nacional de Cardiología "Ignacio Chávez", Ciudad de México, 14080, México.
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Serna J, Bergwitz C. Importance of Dietary Phosphorus for Bone Metabolism and Healthy Aging. Nutrients 2020; 12:E3001. [PMID: 33007883 PMCID: PMC7599912 DOI: 10.3390/nu12103001] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 12/13/2022] Open
Abstract
Inorganic phosphate (Pi) plays a critical function in many tissues of the body: for example, as part of the hydroxyapatite in the skeleton and as a substrate for ATP synthesis. Pi is the main source of dietary phosphorus. Reduced bioavailability of Pi or excessive losses in the urine causes rickets and osteomalacia. While critical for health in normal amounts, dietary phosphorus is plentiful in the Western diet and is often added to foods as a preservative. This abundance of phosphorus may reduce longevity due to metabolic changes and tissue calcifications. In this review, we examine how dietary phosphorus is absorbed in the gut, current knowledge about Pi sensing, and endocrine regulation of Pi levels. Moreover, we also examine the roles of Pi in different tissues, the consequences of low and high dietary phosphorus in these tissues, and the implications for healthy aging.
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Affiliation(s)
- Juan Serna
- Yale College, Yale University, New Haven, CT 06511, USA;
| | - Clemens Bergwitz
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06519, USA
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Abstract
Phosphate is an essential nutrient for life and is a critical component of bone formation, a major signaling molecule, and structural component of cell walls. Phosphate is also a component of high-energy compounds (i.e., AMP, ADP, and ATP) and essential for nucleic acid helical structure (i.e., RNA and DNA). Phosphate plays a central role in the process of mineralization, normal serum levels being associated with appropriate bone mineralization, while high and low serum levels are associated with soft tissue calcification. The serum concentration of phosphate and the total body content of phosphate are highly regulated, a process that is accomplished by the coordinated effort of two families of sodium-dependent transporter proteins. The three isoforms of the SLC34 family (SLC34A1-A3) show very restricted tissue expression and regulate intestinal absorption and renal excretion of phosphate. SLC34A2 also regulates the phosphate concentration in multiple lumen fluids including milk, saliva, pancreatic fluid, and surfactant. Both isoforms of the SLC20 family exhibit ubiquitous expression (with some variation as to which one or both are expressed), are regulated by ambient phosphate, and likely serve the phosphate needs of the individual cell. These proteins exhibit similarities to phosphate transporters in nonmammalian organisms. The proteins are nonredundant as mutations in each yield unique clinical presentations. Further research is essential to understand the function, regulation, and coordination of the various phosphate transporters, both the ones described in this review and the phosphate transporters involved in intracellular transport.
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Affiliation(s)
- Nati Hernando
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Kenneth Gagnon
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Eleanor Lederer
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
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4
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Takeuchi A, Matsuoka S. Integration of mitochondrial energetics in heart with mathematical modelling. J Physiol 2020; 598:1443-1457. [DOI: 10.1113/jp276817] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 01/23/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Ayako Takeuchi
- Department of Integrative and Systems PhysiologyFaculty of Medical Sciencesand Life Science Innovation CenterUniversity of Fukui Fukui 910‐1193 Japan
| | - Satoshi Matsuoka
- Department of Integrative and Systems PhysiologyFaculty of Medical Sciencesand Life Science Innovation CenterUniversity of Fukui Fukui 910‐1193 Japan
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Abstract
Inorganic phosphate (Pi) is essential for signal transduction and cell metabolism, and is also an essential structural component of the extracellular matrix of the skeleton. Pi is sensed in bacteria and yeast at the plasma membrane, which activates intracellular signal transduction to control the expression of Pi transporters and other genes that control intracellular Pi levels. In multicellular organisms, Pi homeostasis must be maintained in the organism and at the cellular level, requiring an endocrine and metabolic Pi-sensing mechanism, about which little is currently known. This Review will discuss the metabolic effects of Pi, which are mediated by Pi transporters, inositol pyrophosphates and SYG1-Pho81-XPR1 (SPX)-domain proteins to maintain cellular phosphate homeostasis in the musculoskeletal system. In addition, we will discuss how Pi is sensed by the human body to regulate the production of fibroblast growth factor 23 (FGF23), parathyroid hormone and calcitriol to maintain serum levels of Pi in a narrow range. New findings on the crosstalk between iron and Pi homeostasis in the regulation of FGF23 expression will also be outlined. Mutations in components of these metabolic and endocrine phosphate sensors result in genetic disorders of phosphate homeostasis, cardiomyopathy and familial basal ganglial calcifications, highlighting the importance of this newly emerging area of research.
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Affiliation(s)
- Sampada Chande
- Section of Endocrinology and Metabolism, Yale University School of Medicine, New Haven, CT, USA
| | - Clemens Bergwitz
- Section of Endocrinology and Metabolism, Yale University School of Medicine, New Haven, CT, USA.
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Saito R, Takeuchi A, Himeno Y, Inagaki N, Matsuoka S. A simulation study on the constancy of cardiac energy metabolites during workload transition. J Physiol 2016; 594:6929-6945. [PMID: 27530892 DOI: 10.1113/jp272598] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Accepted: 08/03/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The cardiac energy metabolites such as ATP, phosphocreatine, ADP and NADH are kept relatively constant during physiological cardiac workload transition. How this is accomplished is not yet clarified, though Ca2+ has been suggested to be one of the possible mechanisms. We constructed a detailed mathematical model of cardiac mitochondria based on experimental data and studied whether known Ca2+ -dependent regulation mechanisms play roles in the metabolite constancy. Model simulations revealed that the Ca2+ -dependent regulation mechanisms have important roles under the in vitro condition of isolated mitochondria where malate and glutamate were mitochondrial substrates, while they have only a minor role and the composition of substrates has marked influence on the metabolite constancy during workload transition under the simulated in vivo condition where many substrates exist. These results help us understand the regulation mechanisms of cardiac energy metabolism during physiological cardiac workload transition. ABSTRACT The cardiac energy metabolites such as ATP, phosphocreatine, ADP and NADH are kept relatively constant over a wide range of cardiac workload, though the mechanisms are not yet clarified. One possible regulator of mitochondrial metabolism is Ca2+ , because it activates several mitochondrial enzymes and transporters. Here we constructed a mathematical model of cardiac mitochondria, including oxidative phosphorylation, substrate metabolism and ion/substrate transporters, based on experimental data, and studied whether the Ca2+ -dependent activation mechanisms play roles in metabolite constancy. Under the in vitro condition of isolated mitochondria, where malate and glutamate were used as mitochondrial substrates, the model well reproduced the Ca2+ and inorganic phosphate (Pi ) dependences of oxygen consumption, NADH level and mitochondrial membrane potential. The Ca2+ -dependent activations of the aspartate/glutamate carrier and the F1 Fo -ATPase, and the Pi -dependent activation of Complex III were key factors in reproducing the experimental data. When the mitochondrial model was implemented in a simple cardiac cell model, simulation of workload transition revealed that cytoplasmic Ca2+ concentration ([Ca2+ ]cyt ) within the physiological range markedly increased NADH level. However, the addition of pyruvate or citrate attenuated the Ca2+ dependence of NADH during the workload transition. Under the simulated in vivo condition where malate, glutamate, pyruvate, citrate and 2-oxoglutarate were used as mitochondrial substrates, the energy metabolites were more stable during the workload transition and NADH level was almost insensitive to [Ca2+ ]cyt . It was revealed that mitochondrial substrates have a significant influence on metabolite constancy during cardiac workload transition, and Ca2+ has only a minor role under physiological conditions.
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Affiliation(s)
- Ryuta Saito
- Biology Research Laboratories, Mitsubishi Tanabe Pharma Corporation, Saitama, 335-8505, Japan.,Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Ayako Takeuchi
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan.,Department of Physiology and Biophysics, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
| | - Yukiko Himeno
- Department of Life Science, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, 606-8507, Japan
| | - Satoshi Matsuoka
- Department of Integrative and Systems Physiology, Faculty of Medical Sciences, University of Fukui, Fukui, 910-1193, Japan.,Department of Physiology and Biophysics, Graduate School of Medicine, Kyoto University, Kyoto, 606-8501, Japan
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Quan X, Das R, Xu S, Cline GW, Wiederkehr A, Wollheim CB, Park KS. Mitochondrial phosphate transport during nutrient stimulation of INS-1E insulinoma cells. Mol Cell Endocrinol 2013; 381:198-209. [PMID: 23939247 DOI: 10.1016/j.mce.2013.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 07/18/2013] [Accepted: 08/03/2013] [Indexed: 11/15/2022]
Abstract
Here, we have investigated the role of inorganic phosphate (Pi) transport in mitochondria of rat clonal β-cells. In α-toxin-permeabilized INS-1E cells, succinate and glycerol-3-phosphate increased mitochondrial ATP release which depends on exogenous ADP and Pi. In the presence of substrates, addition of Pi caused mitochondrial matrix acidification and hyperpolarisation which promoted ATP export. Dissipation of the mitochondrial pH gradient or pharmacological inhibition of Pi transport blocked the effects of Pi on electrochemical gradient and ATP export. Knock-down of the phosphate transporter PiC, however, neither prevented Pi-induced mitochondrial activation nor glucose-induced insulin secretion. Using (31)P NMR we observed reduction of Pi pools during nutrient stimulation of INS-1E cells. Interestingly, Pi loss was less pronounced in mitochondria than in the cytosol. We conclude that matrix alkalinisation is necessary to maintain a mitochondrial Pi pool, at levels sufficient to stimulate energy metabolism in insulin-secreting cells beyond its role as a substrate for ATP synthesis.
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Affiliation(s)
- Xianglan Quan
- Department of Physiology and Institute of Lifestyle Medicine, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
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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: 45] [Impact Index Per Article: 4.1] [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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9
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Effect of heat stress and feeding phosphorus levels on pig electron transport chain gene expression. Animal 2013; 7:1985-93. [DOI: 10.1017/s1751731113001535] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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10
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Differential Expression ESTs Associated with Fluorosis in Rats Liver. Comp Funct Genomics 2012; 2012:208390. [PMID: 22400010 PMCID: PMC3286904 DOI: 10.1155/2012/208390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 11/26/2011] [Indexed: 12/22/2022] Open
Abstract
The fluoride has volcanic activity and abundantly exists in environment combining with other elements as fluoride compounds. Recent researches indicated that the molecular mechanisms of intracellular fluoride toxicity were very complex. However, the molecular mechanisms underlying the effects on gene expression of chronic fluoride-induced damage is unknown, especially the detailed regulatory process of mitochondria. In the present study, we screened the differential expression ESTs associated with fluorosis by DDRT-PCR in rat liver. We gained 8 genes, 3 new ESTs, and 1 unknown function sequence and firstly demonstrated that microsomal glutathione S-transferase 1 (MGST1), ATP synthase H+ transporting mitochondrial F0 complex subunit C1, selenoprotein S, mitochondrial IF1 protein, and mitochondrial succinyl-CoA synthetase alpha subunit were participated in mitochondria metabolism, functional and structural damage process caused by chronic fluorosis. This information will be very helpful for understanding the molecular mechanisms of fluorosis.
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Qi F, Pradhan RK, Dash RK, Beard DA. Detailed kinetics and regulation of mammalian 2-oxoglutarate dehydrogenase. BMC BIOCHEMISTRY 2011; 12:53. [PMID: 21943256 PMCID: PMC3195097 DOI: 10.1186/1471-2091-12-53] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 09/26/2011] [Indexed: 12/22/2022]
Abstract
Background Mitochondrial 2-oxoglutarate (α-ketoglutarate) dehydrogenase complex (OGDHC), a key regulatory point of tricarboxylic acid (TCA) cycle, plays vital roles in multiple pathways of energy metabolism and biosynthesis. The catalytic mechanism and allosteric regulation of this large enzyme complex are not fully understood. Here computer simulation is used to test possible catalytic mechanisms and mechanisms of allosteric regulation of the enzyme by nucleotides (ATP, ADP), pH, and metal ion cofactors (Ca2+ and Mg2+). Results A model was developed based on an ordered ter-ter enzyme kinetic mechanism combined with con-formational changes that involve rotation of one lipoic acid between three catalytic sites inside the enzyme complex. The model was parameterized using a large number of kinetic data sets on the activity of OGDHC, and validated by comparison of model predictions to independent data. Conclusions The developed model suggests a hybrid rapid-equilibrium ping-pong random mechanism for the kinetics of OGDHC, consistent with previously reported mechanisms, and accurately describes the experimentally observed regulatory effects of cofactors on the OGDHC activity. This analysis provides a single consistent theoretical explanation for a number of apparently contradictory results on the roles of phosphorylation potential, NAD (H) oxidation-reduction state ratio, as well as the regulatory effects of metal ions on ODGHC function.
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Affiliation(s)
- Feng Qi
- Biotechnology and Bioengineering Center, Department of Physiology, Medical College of Wisconsin, Milwaukee, 53226, USA
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12
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Rodríguez-Enríquez S, Carreño-Fuentes L, Gallardo-Pérez JC, Saavedra E, Quezada H, Vega A, Marín-Hernández A, Olín-Sandoval V, Torres-Márquez ME, Moreno-Sánchez R. Oxidative phosphorylation is impaired by prolonged hypoxia in breast and possibly in cervix carcinoma. Int J Biochem Cell Biol 2010; 42:1744-51. [DOI: 10.1016/j.biocel.2010.07.010] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 06/18/2010] [Accepted: 07/12/2010] [Indexed: 10/19/2022]
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Masola B, Ngubane NP. The activity of phosphate-dependent glutaminase from the rat small intestine is modulated by ADP and is dependent on integrity of mitochondria. Arch Biochem Biophys 2010; 504:197-203. [PMID: 20831857 DOI: 10.1016/j.abb.2010.09.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 08/29/2010] [Accepted: 09/01/2010] [Indexed: 11/20/2022]
Abstract
The effect of adenine nucleotides and phosphate on rat small intestine phosphate-dependent glutaminase (PDG) activity was investigated in intact mitochondria. Disruption of the integrity of mitochondria by sonication or freeze-thawing resulted in loss of enzyme activity. ADP was the strongest adenine nucleotide activator of the enzyme giving a V(max) that was over 5-fold of that for AMP or ATP. The sigmoid activation curve of PDG by ADP became hyperbolic in presence ATP. ADP also lowered the K(m) for glutamine and increased V(max) and these effects were further enhanced by the presence of ATP. Activation of PDG by phosphate and ADP was not completely additive suggesting some antagonism between the activators. There was no clear relationship between changing ATP/ADP ratios and PDG activity in presence of a constant concentration of phosphate. However, ratios of approximately 1:4 and 4:1 gave the highest and lowest activities, respectively. The pH dependence of PDG activity was affected by phosphate concentration and results suggest that the divalent ion is the activating species.
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Affiliation(s)
- B Masola
- Department of Biochemistry, University of KwaZulu-Natal, Durban, South Africa.
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Bazil JN, Buzzard GT, Rundell AE. Modeling mitochondrial bioenergetics with integrated volume dynamics. PLoS Comput Biol 2010; 6:e1000632. [PMID: 20052270 PMCID: PMC2793388 DOI: 10.1371/journal.pcbi.1000632] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Accepted: 12/02/2009] [Indexed: 11/28/2022] Open
Abstract
Mathematical models of mitochondrial bioenergetics provide powerful analytical tools to help interpret experimental data and facilitate experimental design for elucidating the supporting biochemical and physical processes. As a next step towards constructing a complete physiologically faithful mitochondrial bioenergetics model, a mathematical model was developed targeting the cardiac mitochondrial bioenergetic based upon previous efforts, and corroborated using both transient and steady state data. The model consists of several modified rate functions of mitochondrial bioenergetics, integrated calcium dynamics and a detailed description of the K+-cycle and its effect on mitochondrial bioenergetics and matrix volume regulation. Model simulations were used to fit 42 adjustable parameters to four independent experimental data sets consisting of 32 data curves. During the model development, a certain network topology had to be in place and some assumptions about uncertain or unobserved experimental factors and conditions were explicitly constrained in order to faithfully reproduce all the data sets. These realizations are discussed, and their necessity helps contribute to the collective understanding of the mitochondrial bioenergetics. Mathematically modeling biological systems challenges our current understanding of the physical and biochemical events contributing to the observed dynamics. It requires careful consideration of hypothesized mechanisms, model development assumptions and details regarding the experimental conditions. We have adopted a modeling approach to translate these factors that explicitly considers the thermodynamic constraints, biochemical states and reaction mechanisms during model development. Such models have numerous constant parameters that must be determined. Integrating thermodynamics and detailed mechanistic representation of the principal phenomena help constrain these parameter values; therefore, only a handful of the total number of model parameters (∼10%) must be adjusted during parameter estimation through model simulations. Additionally, all models must undergo some form of corroboration prior to application. In practice, this corroboration should challenge all possible dynamics of the model, but it is recognized that in this data rich world, we are surprisingly data poor. Eventually such developed and corroborated models are capable of supporting current hypotheses, guiding experimental designs and contributing to the overall knowledge base of biological processes.
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Affiliation(s)
- Jason N. Bazil
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Gregery T. Buzzard
- Department of Mathematics, Purdue University, West Lafayette, Indiana, United States of America
| | - Ann E. Rundell
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
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Phillips D, Aponte AM, French SA, Chess DJ, Balaban RS. Succinyl-CoA synthetase is a phosphate target for the activation of mitochondrial metabolism. Biochemistry 2009; 48:7140-9. [PMID: 19527071 DOI: 10.1021/bi900725c] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Succinyl-CoA synthetase (SCS) is the only mitochondrial enzyme capable of ATP production via substrate level phosphorylation in the absence of oxygen, but it also plays a key role in the citric acid cycle, ketone metabolism, and heme synthesis. Inorganic phosphate (P(i)) is a signaling molecule capable of activating oxidative phosphorylation at several sites, including NADH generation and as a substrate for ATP formation. In this study, it was shown that P(i) binds the porcine heart SCS alpha-subunit (SCSalpha) in a noncovalent manner and enhances its enzymatic activity, thereby providing a new target for P(i) activation in mitochondria. Coupling 32P labeling of intact mitochondria with SDS gel electrophoresis revealed that 32P labeling of SCSalpha was enhanced in substrate-depleted mitochondria. Using mitochondrial extracts and purified bacterial SCS (BSCS), we showed that this enhanced 32P labeling resulted from a simple binding of 32P, not covalent protein phosphorylation. The ability of SCSalpha to retain its 32P throughout the SDS denaturing gel process was unique over the entire mitochondrial proteome. In vitro studies also revealed a P(i)-induced activation of SCS activity by more than 2-fold when mitochondrial extracts and purified BSCS were incubated with millimolar concentrations of P(i). Since the level of 32P binding to SCSalpha was increased in substrate-depleted mitochondria, where the matrix P(i) concentration is increased, we conclude that SCS activation by P(i) binding represents another mitochondrial target for the P(i)-induced activation of oxidative phosphorylation and anaerobic ATP production in energy-limited mitochondria.
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Affiliation(s)
- Darci Phillips
- Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-1061, USA
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Strumilo S. Short-term regulation of the alpha-ketoglutarate dehydrogenase complex by energy-linked and some other effectors. BIOCHEMISTRY (MOSCOW) 2006; 70:726-9. [PMID: 16097935 DOI: 10.1007/s10541-005-0177-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The question of regulation of alpha-ketoglutarate dehydrogenase complex (KGDHC) has been considered in the biochemical literature very rarely. Moreover, such information is not usually accurate, especially in biochemical textbooks. From the mini-review of research works published during the last 25 years, the following basic view is clear: a) animal KGDHC is very sensitive to ADP, P(i), and Ca2+; b) these positive effectors increase manifold the affinity of KGDHC to alpha-ketoglutarate; c) KGDHC is inhibited by ATP, NADH, and succinyl-CoA; d) the ATP effect is realized in several ways, probably mainly via opposition versus ADP activation; e) NADH, besides inhibiting dihydrolipoamide dehydrogenase component competitively versus NAD+, decreases the affinity of alpha-ketoglutarate dehydrogenase to substrate and inactivates it; f) thioredoxin protects KGDHC from self-inactivation during catalysis; g) bacterial and plant KGDHC is activated by AMP instead of ADP. These main effects form the basis of short-term regulation of KGDHC.
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Affiliation(s)
- S Strumilo
- Department of Animal Biochemistry, Institute of Biology, University of Bialystok, Bialystok, 15-950, Poland.
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Carvajal K, El Hafidi M, Marin-Hernández A, Moreno-Sánchez R. Structural and functional changes in heart mitochondria from sucrose-fed hypertriglyceridemic rats. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2005; 1709:231-9. [PMID: 16139786 DOI: 10.1016/j.bbabio.2005.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2005] [Revised: 07/26/2005] [Accepted: 08/05/2005] [Indexed: 11/29/2022]
Abstract
In the heart of sugar-induced hypertriglyceridemic (HTG) rats, cardiac performance is impaired with glucose as fuel, but not with fatty acids. Accordingly, the glycolytic flux and the transfer of energy diminish in the HTG heart, in comparison to control heart. To further explore the biochemical nature of such alteration in the HTG heart, the components of the non-glycolytic energy systems involved were evaluated. Total creatine kinase (CK) activity in the myocardial tissue was depressed by 30% in the HTG heart whereas the activity of the mitochondrial CK (mitCK) isoenzyme fraction that is functionally associated with oxidative phosphorylation decreased in isolated HTG heart mitochondria by 45%. Adenylate kinase (AK) was 20% lower in the HTG heart. In contrast, respiratory rates with 2-oxoglutarate (2-OG) and pyruvate/malate (pyr) were significantly higher in HTG heart mitochondria than in control mitochondria. 2-OG dehydrogenase activity was also higher in HTG mitochondria. Respiration with succinate was similar in both groups. Content of cytochromes b, c + c1 and a + a3, and cytochrome c oxidase activity, were also similar in the two kinds of mitochondria. A larger content of saturated and monounsaturated fatty acids was found in the HTG mitochondrial membranes with no changes in phospholipids composition or cholesterol content. Mitochondrial membranes from HTG hearts were more rigid, which correlated with the generation of higher membrane potentials. As the mitochondrial function was preserved or even enhanced in the HTG heart, these results indicated that deficiency in energy transfer was associated with impairment in mitCK and AK. This situation brought about uncoupling between the site of ATP production and the site of ATP consumption (contractile machinery), in spite of compensatory increase in mitochondrial oxidative capacity and membrane potential generation.
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Affiliation(s)
- Karla Carvajal
- Department of Biochemistry, Instituto Nacional de Cardiología. Juan Badiano #1, Col. Sección XVI, Tlalpan, México, D.F., Mexico.
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Hernández-Esquivel L, Marín-Hernández A, Pavón N, Carvajal K, Moreno-Sánchez R. Cardiotoxicity of copper-based antineoplastic drugs casiopeinas is related to inhibition of energy metabolism. Toxicol Appl Pharmacol 2005; 212:79-88. [PMID: 16051288 DOI: 10.1016/j.taap.2005.06.023] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Revised: 06/17/2005] [Accepted: 06/23/2005] [Indexed: 11/19/2022]
Abstract
Isolated rat hearts were perfused with glucose, octanoate or glucose + octanoate and different concentrations of the copper-based antineoplastic drugs casiopeina II-gly (CSII) or casiopeina III-i-a (CSIII). In isolated perfused hearts with glucose + octanoate, both casiopeinas induced diminution in cardiac work and O2 consumption with half-maximal inhibitory concentrations (IC50) of 4 (CSII) and 4.6 (CSIII) microM, after 1 h of perfusion. Strong inhibition of the pyruvate and 2-oxoglutarate dehydrogenases as well as total creatine kinase by casiopeinas suggested that ATP generation by oxidative phosphorylation and its transfer towards myofibrils were targets for these drugs. In consequence, the cellular contents of ATP and phosphocreatine were also lowered by casiopeinas. Remarkably, casiopeinas were less toxic than adriamycin (IC50 = 2.6 microM), a well-known potent cardiotoxic and antineoplastic drug, which has a wide clinical use. In an open-chest animal, which is a more physiological model than the isolated heart, femoral administration of 1 microM drug revealed that CSII was innocuous very likely due to strong binding to serum albumin, whereas adriamycin induced again a potent cardiotoxic effect (diminution in heart rate and severe depression of systolic blood pressure). Thus, it seems that casiopeinas are a group of new antineoplastic drugs with milder secondary toxic effects than proven drugs such as adriamycin.
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Affiliation(s)
- Luz Hernández-Esquivel
- Instituto Nacional de Cardiología, Departamento de Bioquímica, Juan Badiano No. 1, Col. Sección XVI, 14080 Tlalpan DF, México
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Joubert F, Fales HM, Wen H, Combs CA, Balaban RS. NADH enzyme-dependent fluorescence recovery after photobleaching (ED-FRAP): applications to enzyme and mitochondrial reaction kinetics, in vitro. Biophys J 2004; 86:629-45. [PMID: 14695307 PMCID: PMC1303832 DOI: 10.1016/s0006-3495(04)74141-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
NADH enzyme-dependent fluorescence recovery after photobleaching (ED-FRAP) was evaluated for studying enzyme kinetics in vitro and in isolated mitochondria. Mass, optical, and nuclear magnetic resonance spectroscopy data were consistent with the UV NADH photolysis reaction being NADH --> NAD* + H+ + e-. The overall net reaction was O2 + 2NADH + 2H+ --> 2NAD+ + 2H2O, or in the presence of other competing electron acceptors such as cytochrome c, NADH + 2Cyt(ox) --> NAD+ + H+ + 2Cyt(red). Solution pH could differentiate between these free-radical scavenging pathways. These net reactions represent the photooxidation of NADH to NAD+. Kinetic models and acquisition schemes were developed, varying [NADH] and [NAD] by altering NADH photolysis levels, for extracting kinetic parameters. UV irradiation levels used did not damage mitochondrial function or enzymatic activity. In mitochondria, [NADH] is a high affinity product inhibitor that significantly reduced the NADH regeneration rate. Matrix NADH regeneration only slightly exceeded the net rate of NADH consumption, suggesting that the NADH regeneration process is far from equilibrium. Evaluation of NADH regeneration in active mitochondria, in comparison to rotenone-treated preparations, revealed other regulatory elements in addition to matrix [NADH] and [NAD] that have yet to be fully characterized. These studies demonstrate that the rapid UV photolysis of NADH to NAD is an effective tool in evaluating the steady-state kinetic properties of enzyme systems. Initial data support the notion that the NADH regeneration process is far from equilibrium in mitochondria and is potentially controlled by NADH levels as well as several other matrix factors.
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Affiliation(s)
- Frederic Joubert
- Laboratory of Cardiac Energetics, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1061, USA
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Bose S, French S, Evans FJ, Joubert F, Balaban RS. Metabolic network control of oxidative phosphorylation: multiple roles of inorganic phosphate. J Biol Chem 2003; 278:39155-65. [PMID: 12871940 DOI: 10.1074/jbc.m306409200] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphate (Pi) is a putative cytosolic signaling molecule in the regulation of oxidative phosphorylation. Here, by using a multiparameter monitoring system, we show that Pi controls oxidative phosphorylation in a balanced fashion, modulating both the generation of useful potential energy and the formation of ATP by F1F0-ATPase in heart and skeletal muscle mitochondria. In these studies the effect of Pi was determined on the mitochondria [NADH], NADH generating capacity, matrix pH, membrane potential, oxygen consumption, and cytochrome reduction level. Pi enhanced NADH generation and was obligatory for electron flow under uncoupled conditions. Pi oxidized cytochrome b (cyto-b) and reduced cytochrome c (cyto-c), potentially improving the coupling between the NADH free energy and the proton motive force. The apparent limitation in reducing equivalent flow between cyto-b and cyto-c in the absence of Pi was confirmed in the intact heart by using optical spectroscopic techniques under conditions with low cytosolic [Pi]. These results demonstrate that Pi signaling results in the balanced modulation of oxidative phosphorylation, by influencing both deltaGH+ generation and ATP production, which may contribute to the energy metabolism homeostasis observed in intact systems.
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Affiliation(s)
- Salil Bose
- Laboratory of Cardiac Energetics, NHLBI, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA
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Marín-Hernández A, Gracia-Mora I, Ruiz-Ramírez L, Moreno-Sánchez R. Toxic effects of copper-based antineoplastic drugs (Casiopeinas) on mitochondrial functions. Biochem Pharmacol 2003; 65:1979-89. [PMID: 12787878 DOI: 10.1016/s0006-2952(03)00212-0] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To elucidate some of the subcellular and biochemical mechanisms of toxicity of metal-based antineoplastic drugs, mitochondria and cells were exposed to Casiopeinas), a new class of copper-based compounds with high antineoplastic activity. The rates of respiration and swelling, the H(+) gradient, and the activities of succinate (SDH) and 2-oxoglutarate dehydrogenases (2-OGDH) and ATPase were measured in mitochondria isolated from rat liver, kidney, heart, and hepatoma AS-30D. Also, oligomycin-sensitive respiration and ATP content in hepatoma AS-30D cells were determined. Casiopeinas) (CS) II-gly and III-i inhibited the rates of state 3 and uncoupled respiration in mitochondria. CS II was 10 times more potent than CS III. The sensitivity to CS II was 4-5-fold higher in mitochondria incubated with 2-OG than with succinate. Thus, at low concentrations (< or =10 nmol (mg protein)(-1); 10 microM), CS II disturbed mitochondrial functions only when 2-OG was present, due to a specific inhibition of 2-OGDH. At high concentrations (> or =15nmol (mg protein)(-1)), CS II-induced stimulation of basal respiration, followed by a strong inhibition, which correlated with K(+)-dependent swelling and cytochrome c release, respectively; K(+)-channel openers induce a similar mitochondrial response. Mitochondria from liver, kidney and hepatoma showed a similar sensitivity towards CS II, whereas heart mitochondria were more resistant. Oxidative phosphorylation and ATP content were also decreased in tumor cells by CS II. The data suggested that CS affected several different mitochondrial sites, bringing about inhibition of respiration and ATP synthesis, which could compromise energy-dependent processes such as cellular duplication.
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Affiliation(s)
- Alvaro Marín-Hernández
- Departamento de Bioquímica, Instituto Nacional de Cardiología, Juan Badiano # 1, Col. Sección XVI, Tlalpan, México D.F. 14080, Mexico
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