1
|
Podinic T, Limoges L, Monaco C, MacAndrew A, Minhas M, Nederveen J, Raha S. Cannabidiol Disrupts Mitochondrial Respiration and Metabolism and Dysregulates Trophoblast Cell Differentiation. Cells 2024; 13:486. [PMID: 38534330 DOI: 10.3390/cells13060486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 03/01/2024] [Accepted: 03/06/2024] [Indexed: 03/28/2024] Open
Abstract
Trophoblast differentiation is a crucial process in the formation of the placenta where cytotrophoblasts (CTs) differentiate and fuse to form the syncytiotrophoblast (ST). The bioactive components of cannabis, such as Δ9-THC, are known to disrupt trophoblast differentiation and fusion, as well as mitochondrial dynamics and respiration. However, less is known about the impact of cannabidiol (CBD) on trophoblast differentiation. Due to the central role of mitochondria in stem cell differentiation, we evaluated the impact of CBD on trophoblast mitochondrial function and differentiation. Using BeWo b30 cells, we observed decreased levels of mRNA for markers of syncytialization (GCM1, ERVW1, hCG) following 20 µM CBD treatment during differentiation. In CTs, CBD elevated transcript levels for the mitochondrial and cellular stress markers HSP60 and HSP70, respectively. Furthermore, CBD treatment also increased the lipid peroxidation and oxidative damage marker 4-hydroxynonenal. Mitochondrial membrane potential, basal respiration and ATP production were diminished with the 20 µM CBD treatment in both sub-lineages. mRNA levels for endocannabinoid system (ECS) components (FAAH, NAPEPLD, TRPV1, CB1, CB2, PPARγ) were altered differentially by CBD in CTs and STs. Overall, we demonstrate that CBD impairs trophoblast differentiation and fusion, as well as mitochondrial bioenergetics and redox homeostasis.
Collapse
Affiliation(s)
- Tina Podinic
- Graduate Program in Medical Sciences, Department of Pediatrics, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Louise Limoges
- Graduate Program in Medical Sciences, Department of Pediatrics, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Cristina Monaco
- Graduate Program in Medical Sciences, Department of Pediatrics, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Andie MacAndrew
- Graduate Program in Medical Sciences, Department of Pediatrics, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Mahek Minhas
- Department of Pediatrics, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
- Department of Kinesiology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Joshua Nederveen
- Department of Pediatrics, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
- Department of Kinesiology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Sandeep Raha
- Graduate Program in Medical Sciences, Department of Pediatrics, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| |
Collapse
|
2
|
Nègre-Salvayre A, Salvayre R. Reactive Carbonyl Species and Protein Lipoxidation in Atherogenesis. Antioxidants (Basel) 2024; 13:232. [PMID: 38397830 PMCID: PMC10886358 DOI: 10.3390/antiox13020232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/08/2024] [Accepted: 02/09/2024] [Indexed: 02/25/2024] Open
Abstract
Atherosclerosis is a multifactorial disease of medium and large arteries, characterized by the presence of lipid-rich plaques lining the intima over time. It is the main cause of cardiovascular diseases and death worldwide. Redox imbalance and lipid peroxidation could play key roles in atherosclerosis by promoting a bundle of responses, including endothelial activation, inflammation, and foam cell formation. The oxidation of polyunsaturated fatty acids generates various lipid oxidation products such as reactive carbonyl species (RCS), including 4-hydroxy alkenals, malondialdehyde, and acrolein. RCS covalently bind to nucleophilic groups of nucleic acids, phospholipids, and proteins, modifying their structure and activity and leading to their progressive dysfunction. Protein lipoxidation is the non-enzymatic post-translational modification of proteins by RCS. Low-density lipoprotein (LDL) oxidation and apolipoprotein B (apoB) modification by RCS play a major role in foam cell formation. Moreover, oxidized LDLs are a source of RCS, which form adducts on a huge number of proteins, depending on oxidative stress intensity, the nature of targets, and the availability of detoxifying systems. Many systems are affected by lipoxidation, including extracellular matrix components, membranes, cytoplasmic and cytoskeletal proteins, transcription factors, and other components. The mechanisms involved in lipoxidation-induced vascular dysfunction are not fully elucidated. In this review, we focus on protein lipoxidation during atherogenesis.
Collapse
Affiliation(s)
- Anne Nègre-Salvayre
- Inserm Unité Mixte de Recherche (UMR), 1297 Toulouse, Centre Hospitalier Universitaire (CHU) Rangueil—BP 84225, 31432 Toulouse CEDEX 4, France;
- Faculty of Medicine, University of Toulouse, 31432 Toulouse, France
| | - Robert Salvayre
- Inserm Unité Mixte de Recherche (UMR), 1297 Toulouse, Centre Hospitalier Universitaire (CHU) Rangueil—BP 84225, 31432 Toulouse CEDEX 4, France;
- Faculty of Medicine, University of Toulouse, 31432 Toulouse, France
| |
Collapse
|
3
|
Schiffer TA, Löf L, Gallini R, Kamali-Moghaddam M, Carlström M, Palm F. Mitochondrial Respiration-Dependent ANT2-UCP2 Interaction. Front Physiol 2022; 13:866590. [PMID: 35694398 PMCID: PMC9177158 DOI: 10.3389/fphys.2022.866590] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/09/2022] [Indexed: 11/13/2022] Open
Abstract
Adenine nucleotide translocases (ANTs) and uncoupling proteins (UCPs) are known to facilitate proton leak across the inner mitochondrial membrane. However, it remains to be unravelled whether UCP2/3 contribute to significant amount of proton leak in vivo. Reports are indicative of UCP2 dependent proton-coupled efflux of C4 metabolites from the mitochondrial matrix. Previous studies have suggested that UCP2/3 knockdown (KD) contributes to increased ANT-dependent proton leak. Here we investigated the hypothesis that interaction exists between the UCP2 and ANT2 proteins, and that such interaction is regulated by the cellular metabolic demand. Protein-protein interaction was evaluated using reciprocal co-immunoprecipitation and in situ proximity ligation assay. KD of ANT2 and UCP2 was performed by siRNA in human embryonic kidney cells 293A (HEK293A) cells. Mitochondrial and cellular respiration was measured by high-resolution respirometry. ANT2-UCP2 interaction was demonstrated, and this was dependent on cellular metabolism. Inhibition of ATP synthase promoted ANT2-UCP2 interaction whereas high cellular respiration, induced by adding the mitochondrial uncoupler FCCP, prevented interaction. UCP2 KD contributed to increased carboxyatractyloside (CATR) sensitive proton leak, whereas ANT2 and UCP2 double KD reduced CATR sensitive proton leak, compared to UCP2 KD. Furthermore, proton leak was reduced in double KD compared to UCP2 KD. In conclusion, our results show that there is an interaction between ANT2-UCP2, which appears to be dynamically regulated by mitochondrial respiratory activity. This may have implications in the regulation of mitochondrial efficiency or cellular substrate utilization as increased activity of UCP2 may promote a switch from glucose to fatty acid metabolism.
Collapse
Affiliation(s)
- Tomas A. Schiffer
- Department of Physiology and Pharmacology, Karolinska Institutet, Solna, Sweden
- *Correspondence: Tomas A. Schiffer,
| | - Liza Löf
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Radiosa Gallini
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Masood Kamali-Moghaddam
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Mattias Carlström
- Department of Physiology and Pharmacology, Karolinska Institutet, Solna, Sweden
| | - Fredrik Palm
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| |
Collapse
|
4
|
Reyes-Jiménez E, Ramírez-Hernández AA, Santos-Álvarez JC, Velázquez-Enríquez JM, Pina-Canseco S, Baltiérrez-Hoyos R, Vásquez-Garzón VR. Involvement of 4-hydroxy-2-nonenal in the pathogenesis of pulmonary fibrosis. Mol Cell Biochem 2021; 476:4405-4419. [PMID: 34463938 DOI: 10.1007/s11010-021-04244-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 08/12/2021] [Indexed: 01/19/2023]
Abstract
Pulmonary fibrosis is a chronic progressive disease with high incidence, prevalence, and mortality rates worldwide. It is characterized by excessive accumulation of extracellular matrix in the lung parenchyma. The cellular and molecular mechanisms involved in its pathogenesis are complex, and some are still unknown. Several studies indicate that oxidative stress, characterized by overproduction of 4-hydroxy-2-nonenal (4-HNE), is an important player in pulmonary fibrosis. 4-HNE is a highly reactive compound derived from polyunsaturated fatty acids that can react with proteins, phospholipids, and nucleic acids. Thus, many of the altered cellular mechanisms that contribute to this disease can be explained by the participation of 4-HNE. Here, we summarize the current knowledge on the molecular states and signal transduction pathways that contribute to the pathogenesis of pulmonary fibrosis. Furthermore, we describe the participation of 4-HNE in various mechanisms involved in pulmonary fibrosis development, with a focus on the cell populations involved in the initiation, development, and maintenance of the fibrotic process, mainly alveolar cells, endothelial cells, macrophages, and inflammatory cells. Due to its characteristic activity as a second messenger, 4-HNE, in addition to being a consequence of oxidative stress, can support maintenance of the inflammatory and fibrotic process by spreading the effects of reactive oxygen species (ROS). Thus, regulation of 4-HNE levels could be a viable strategy to reduce its effects on the mechanisms involved in pulmonary fibrosis development.
Collapse
Affiliation(s)
- Edilburga Reyes-Jiménez
- Laboratorio de Fibrosis y Cáncer, Facultad de Medicina y Cirugía, Universidad Autónoma Benito Juárez de Oaxaca, Oaxaca, Mexico
| | - Alma Aurora Ramírez-Hernández
- Laboratorio de Fibrosis y Cáncer, Facultad de Medicina y Cirugía, Universidad Autónoma Benito Juárez de Oaxaca, Oaxaca, Mexico
| | - Jovito Cesar Santos-Álvarez
- Laboratorio de Fibrosis y Cáncer, Facultad de Medicina y Cirugía, Universidad Autónoma Benito Juárez de Oaxaca, Oaxaca, Mexico
| | - Juan Manuel Velázquez-Enríquez
- Laboratorio de Fibrosis y Cáncer, Facultad de Medicina y Cirugía, Universidad Autónoma Benito Juárez de Oaxaca, Oaxaca, Mexico
| | | | - Rafael Baltiérrez-Hoyos
- CONACYT-Facultad de Medicina y Cirugía, Universidad Autónoma Benito Juárez de Oaxaca, Oaxaca, Mexico
| | | |
Collapse
|
5
|
Cardinale DA, Gejl KD, Petersen KG, Nielsen J, Ørtenblad N, Larsen FJ. Short-term intensified training temporarily impairs mitochondrial respiratory capacity in elite endurance athletes. J Appl Physiol (1985) 2021; 131:388-400. [PMID: 34110230 DOI: 10.1152/japplphysiol.00829.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The maintenance of healthy and functional mitochondria is the result of a complex mitochondrial turnover and herein quality-control program that includes both mitochondrial biogenesis and autophagy of mitochondria. The aim of this study was to examine the effect of an intensified training load on skeletal muscle mitochondrial quality control in relation to changes in mitochondrial oxidative capacity, maximal oxygen consumption, and performance in highly trained endurance athletes. Elite endurance athletes (n = 27) performed high-intensity interval exercise followed by moderate-intensity continuous exercise 3 days per week for 4 wk in addition to their usual volume of training. Mitochondrial oxidative capacity, abundance of mitochondrial proteins, markers of autophagy, and antioxidant capacity of skeletal muscle were assessed in skeletal muscle biopsies before and after the intensified training period. The intensified training period increased several autophagy markers suggesting an increased turnover of mitochondrial and cytosolic proteins. In permeabilized muscle fibers, mitochondrial respiration was ∼20% lower after training although some markers of mitochondrial density increased by 5%-50%, indicative of a reduced mitochondrial quality by the intensified training intervention. The antioxidative proteins UCP3, ANT1, and SOD2 were increased after training, whereas we found an inactivation of aconitase. In agreement with the lower aconitase activity, the amount of mitochondrial LON protease that selectively degrades oxidized aconitase was doubled. Together, this suggests that mitochondrial respiratory function is impaired during the initial recovery from a period of intensified endurance training whereas mitochondrial quality control is slightly activated in highly trained skeletal muscle.NEW & NOTEWORTHY We show that mitochondrial respiration is temporarily impaired after a period of intensified exercise training in elite athletes. In parallel, proteins involved in the antioxidative response including SOD2, UCP3, and ANT2 were upregulated, whereas mitochondrial biogenesis was slightly activated. Despite the mitochondrial respiratory impairments, physical performance was improved a few days after the intense training period.
Collapse
Affiliation(s)
- Daniele A Cardinale
- Åstrand Laboratory, Department of Physiology, Nutrition, and Biomechanics, The Swedish School of Sport and Health Sciences (GIH), Stockholm, Sweden.,Elite Performance Centre, Bosön-Swedish Sports Confederation, Lidingö, Sweden
| | - Kasper D Gejl
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Kristine G Petersen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Filip J Larsen
- Åstrand Laboratory, Department of Physiology, Nutrition, and Biomechanics, The Swedish School of Sport and Health Sciences (GIH), Stockholm, Sweden
| |
Collapse
|
6
|
Liu Y, Sun B, Zhang S, Li J, Qi J, Bai C, Zhang J, Liang S. Glycine alleviates fluoride-induced oxidative stress, apoptosis and senescence in a porcine testicular Sertoli cell line. Reprod Domest Anim 2021; 56:884-896. [PMID: 33738852 DOI: 10.1111/rda.13930] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 03/16/2021] [Indexed: 12/18/2022]
Abstract
Glycine is a well-known free radical scavenger in the cellular antioxidant system that prevents oxidative damage and apoptosis. Excessive fluoride exposure is associated with multiple types of cellular damage in humans and animals. The objective of the present study was to investigate the protective effects of glycine on sodium fluoride (NaF) exposure and the possible underlying mechanisms in a porcine testicular Sertoli cell line model. Cellular viability and proliferation were examined following NaF exposure and glycine supplementation, and glycine dramatically ameliorated the decreases in NaF-induced porcine testicular Sertoli cell viability and proliferation. Further investigations revealed that glycine decreased NaF-induced intracellular reactive oxygen species production, DNA fragment accumulation and the apoptosis incidence in the porcine testicular Sertoli cell line; in addition, glycine improved mitochondrial function and ATP production. Notably, results of the SPiDER-β-Gal analysis suggested that glycine alleviated NaF-induced cellular senescence and downregulated P53, P21, HMGA2 and P16INK4a gene expression in the porcine testicular Sertoli cell line. Collectively, the beneficial effects of glycine alleviate NaF-induced oxidative stress, apoptosis and senescence, and together with our previous findings, support the hypothesis that glycine plays an important role in protecting against NaF exposure-induced impairments in the porcine testicular Sertoli cell line.
Collapse
Affiliation(s)
- Ying Liu
- Department of Animals Sciences, College of Animal Sciences, Jilin University, Changchun, China
| | - Boxing Sun
- Department of Animals Sciences, College of Animal Sciences, Jilin University, Changchun, China
| | - Shaoxuan Zhang
- Department of Animals Sciences, College of Animal Sciences, Jilin University, Changchun, China
| | - Jing Li
- Department of Animals Sciences, College of Animal Sciences, Jilin University, Changchun, China
| | - Jiajia Qi
- Department of Animals Sciences, College of Animal Sciences, Jilin University, Changchun, China
| | - Chunyan Bai
- Department of Animals Sciences, College of Animal Sciences, Jilin University, Changchun, China
| | - Jiabao Zhang
- Department of Animals Sciences, College of Animal Sciences, Jilin University, Changchun, China
| | - Shuang Liang
- Department of Animals Sciences, College of Animal Sciences, Jilin University, Changchun, China
| |
Collapse
|
7
|
Petrick HL, Foley KP, Zlitni S, Brunetta HS, Paglialunga S, Miotto PM, Politis-Barber V, O’Dwyer C, Philbrick DJ, Fullerton MD, Schertzer JD, Holloway GP. Adipose Tissue Inflammation Is Directly Linked to Obesity-Induced Insulin Resistance, while Gut Dysbiosis and Mitochondrial Dysfunction Are Not Required. FUNCTION (OXFORD, ENGLAND) 2020; 1:zqaa013. [PMID: 34278304 PMCID: PMC8276887 DOI: 10.1093/function/zqaa013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/17/2020] [Accepted: 08/21/2020] [Indexed: 01/06/2023]
Abstract
Obesity is associated with adipose tissue hypertrophy, systemic inflammation, mitochondrial dysfunction, and intestinal dysbiosis. Rodent models of high-fat diet (HFD)-feeding or genetic deletion of multifunctional proteins involved in immunity and metabolism are often used to probe the etiology of obesity; however, these models make it difficult to divorce the effects of obesity, diet composition, or immunity on endocrine regulation of blood glucose. We, therefore, investigated the importance of adipose inflammation, mitochondrial dysfunction, and gut dysbiosis for obesity-induced insulin resistance using a spontaneously obese mouse model. We examined metabolic changes in skeletal muscle, adipose tissue, liver, the intestinal microbiome, and whole-body glucose control in spontaneously hyperphagic C57Bl/6J mice compared to lean littermates. A separate subset of lean and obese mice was subject to 8 weeks of obesogenic HFD feeding, or to pair feeding of a standard rodent diet. Hyperphagia, obesity, adipose inflammation, and insulin resistance were present in obese mice despite consuming a standard rodent diet, and these effects were blunted with caloric restriction. However, hyperphagic obese mice had normal mitochondrial respiratory function in all tissues tested and no discernable intestinal dysbiosis relative to lean littermates. In contrast, feeding mice an obesogenic HFD altered the composition of the gut microbiome, impaired skeletal muscle mitochondrial bioenergetics, and promoted poor glucose control. These data show that adipose inflammation and redox stress occurred in all models of obesity, but gut dysbiosis and mitochondrial respiratory dysfunction are not always required for obesity-induced insulin resistance. Rather, changes in the intestinal microbiome and mitochondrial bioenergetics may reflect physiological consequences of HFD feeding.
Collapse
Affiliation(s)
- Heather L Petrick
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Kevin P Foley
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Soumaya Zlitni
- Departments of Genetics and Medicine, Stanford University, Stanford, 94305, CA, USA
| | - Henver S Brunetta
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada,Department of Physiological Sciences, Federal University of Santa Catarina, Florianopolis, Santa Catarina, Brazil
| | - Sabina Paglialunga
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Paula M Miotto
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Valerie Politis-Barber
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Conor O’Dwyer
- Department of Biochemistry, Microbiology and Immunology, Centre for Inflammation, Infection and Immunity, Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON, Canada
| | - Diana J Philbrick
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Morgan D Fullerton
- Department of Biochemistry, Microbiology and Immunology, Centre for Inflammation, Infection and Immunity, Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON, Canada
| | - Jonathan D Schertzer
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada,Address correspondence to G.P.H. (e-mail: )
| |
Collapse
|
8
|
Braz GRF, da Silva AI, Silva SCA, Pedroza AAS, de Lemos MDT, de Lima FAS, Silva TLA, Lagranha CJ. Chronic serotonin reuptake inhibition uncouples brown fat mitochondria and induces beiging/browning process of white fat in overfed rats. Life Sci 2020; 245:117307. [DOI: 10.1016/j.lfs.2020.117307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 01/10/2020] [Accepted: 01/13/2020] [Indexed: 02/07/2023]
|
9
|
Mitochondria as a Source and a Target for Uremic Toxins. Int J Mol Sci 2019; 20:ijms20123094. [PMID: 31242575 PMCID: PMC6627204 DOI: 10.3390/ijms20123094] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/19/2019] [Accepted: 06/21/2019] [Indexed: 01/23/2023] Open
Abstract
Elucidation of molecular and cellular mechanisms of the uremic syndrome is a very challenging task. More than 130 substances are now considered to be "uremic toxins" and represent a very diverse group of molecules. The toxicity of these molecules affects many cellular processes, and expectably, some of them are able to disrupt mitochondrial functioning. However, mitochondria can be the source of uremic toxins as well, as the mitochondrion can be the site of complete synthesis of the toxin, whereas in some scenarios only some enzymes of the pathway of toxin synthesis are localized here. In this review, we discuss the role of mitochondria as both the target and source of pathological processes and toxic compounds during uremia. Our analysis revealed about 30 toxins closely related to mitochondria. Moreover, since mitochondria are key regulators of cellular redox homeostasis, their functioning might directly affect the production of uremic toxins, especially those that are products of oxidation or peroxidation of cellular components, such as aldehydes, advanced glycation end-products, advanced lipoxidation end-products, and reactive carbonyl species. Additionally, as a number of metabolic products can be degraded in the mitochondria, mitochondrial dysfunction would therefore be expected to cause accumulation of such toxins in the organism. Alternatively, many uremic toxins (both made with the participation of mitochondria, and originated from other sources including exogenous) are damaging to mitochondrial components, especially respiratory complexes. As a result, a positive feedback loop emerges, leading to the amplification of the accumulation of uremic solutes. Therefore, uremia leads to the appearance of mitochondria-damaging compounds, and consecutive mitochondrial damage causes a further rise of uremic toxins, whose synthesis is associated with mitochondria. All this makes mitochondrion an important player in the pathogenesis of uremia and draws attention to the possibility of reducing the pathological consequences of uremia by protecting mitochondria and reducing their role in the production of uremic toxins.
Collapse
|
10
|
Devaux JBL, Hickey AJR, Renshaw GMC. Mitochondrial plasticity in the cerebellum of two anoxia-tolerant sharks: contrasting responses to anoxia/reoxygenation. J Exp Biol 2019; 222:jeb.191353. [DOI: 10.1242/jeb.191353] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 02/20/2019] [Indexed: 11/20/2022]
Abstract
Exposure to anoxia leads to rapid ATP depletion, alters metabolic pathways and exacerbates succinate accumulation. Upon re-oxygenation, the preferential oxidation of accumulated succinate most often impairs mitochondrial function. Few species can survive prolonged periods of hypoxia and anoxia at tropical temperatures and those that do may rely on mitochondria plasticity in response to disruptions to oxygen availability. Two carpet sharks, the epaulette shark (Hemiscyllium ocellatum; ES) and the grey carpet shark (Chiloscyllium punctatum; GCS) display different adaptive responses to prolonged anoxia: while the ES enters energy conserving metabolic depression, the GCS temporarily elevates its haematocrit prolonging oxygen delivery. High-resolution respirometry was used to investigate mitochondrial function in the cerebellum, a highly metabolically active organ that is oxygen sensitive and vulnerable to injury after anoxia/re-oxygenation (AR).
Succinate was titrated into cerebellar preparations in vitro, with or without pre-exposure to AR, then the activity of mitochondrial complexes was examined. Like most vertebrates, GCS mitochondria significantly increased succinate oxidation rates, with impaired complex I function post-AR. In contrast, ES mitochondria inhibited succinate oxidation rates and both complex I and II capacities were conserved, resulting in preservation of oxidative phosphorylation capacity post-AR.
Divergent mitochondrial plasticity elicited by elevated succinate post A/R parallels the inherently divergent physiological adaptations of these animals to prolonged anoxia, namely the absence (GCS) and presence of metabolic depression (ES). Since anoxia tolerance in these species also occurs at temperatures close to that of humans, examining their mitochondrial responses to AR could provide insights for novel interventions in clinical settings.
Collapse
Affiliation(s)
- Jules B. L. Devaux
- School of Biological Sciences, The University of Auckland, Auckland 1142, New Zealand
| | - Anthony J. R. Hickey
- School of Biological Sciences, The University of Auckland, Auckland 1142, New Zealand
| | - Gillian M. C. Renshaw
- Hypoxia and Ischemia Research Unit, School of Allied Sciences, Griffith University, Gold Coast campus, QLD 4222, Australia
| |
Collapse
|
11
|
Cardinale DA, Larsen FJ, Schiffer TA, Morales-Alamo D, Ekblom B, Calbet JAL, Holmberg HC, Boushel R. Superior Intrinsic Mitochondrial Respiration in Women Than in Men. Front Physiol 2018; 9:1133. [PMID: 30174617 PMCID: PMC6108574 DOI: 10.3389/fphys.2018.01133] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 07/30/2018] [Indexed: 11/25/2022] Open
Abstract
Sexual dimorphism is apparent in humans, however, to date no studies have investigated mitochondrial function focusing on intrinsic mitochondrial respiration (i.e., mitochondrial respiration for a given amount of mitochondrial protein) and mitochondrial oxygen affinity (p50mito) in relation to biological sex in human. A skeletal muscle biopsy was donated by nine active women, and ten men matched for maximal oxygen consumption (VO2max) and by nine endurance trained men. Intrinsic mitochondrial respiration, assessed in isolated mitochondria, was higher in women compared to men when activating complex I (CIP) and complex I+II (CI+IIP) (p < 0.05), and was similar to trained men (CIP, p = 0.053; CI+IIP, p = 0.066). Proton leak and p50mito were higher in women compared to men independent of VO2max. In conclusion, significant novel differences in mitochondrial oxidative function, intrinsic mitochondrial respiration and p50mito exist between women and men. These findings may represent an adaptation in the oxygen cascade in women to optimize muscle oxygen uptake to compensate for a lower oxygen delivery during exercise.
Collapse
Affiliation(s)
- Daniele A Cardinale
- Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Filip J Larsen
- Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Tomas A Schiffer
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - David Morales-Alamo
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Gran Canaria, Spain
| | - Björn Ekblom
- Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Jose A L Calbet
- Department of Physical Education, University of Las Palmas de Gran Canaria, Las Palmas, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Gran Canaria, Spain.,School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada
| | - Hans-Christer Holmberg
- School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada.,Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Robert Boushel
- School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
12
|
Berry BJ, Trewin AJ, Amitrano AM, Kim M, Wojtovich AP. Use the Protonmotive Force: Mitochondrial Uncoupling and Reactive Oxygen Species. J Mol Biol 2018; 430:3873-3891. [PMID: 29626541 DOI: 10.1016/j.jmb.2018.03.025] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/21/2018] [Accepted: 03/26/2018] [Indexed: 02/06/2023]
Abstract
Mitochondrial respiration results in an electrochemical proton gradient, or protonmotive force (pmf), across the mitochondrial inner membrane. The pmf is a form of potential energy consisting of charge (∆ψm) and chemical (∆pH) components, that together drive ATP production. In a process called uncoupling, proton leak into the mitochondrial matrix independent of ATP production dissipates the pmf and energy is lost as heat. Other events can directly dissipate the pmf independent of ATP production as well, such as chemical exposure or mechanisms involving regulated mitochondrial membrane electrolyte transport. Uncoupling has defined roles in metabolic plasticity and can be linked through signal transduction to physiologic events. In the latter case, the pmf impacts mitochondrial reactive oxygen species (ROS) production. Although capable of molecular damage, ROS also have signaling properties that depend on the timing, location, and quantity of their production. In this review, we provide a general overview of mitochondrial ROS production, mechanisms of uncoupling, and how these work in tandem to affect physiology and pathologies, including obesity, cardiovascular disease, and immunity. Overall, we highlight that isolated bioenergetic models-mitochondria and cells-only partially recapitulate the complex link between the pmf and ROS signaling that occurs in vivo.
Collapse
Affiliation(s)
- Brandon J Berry
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
| | - Adam J Trewin
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
| | - Andrea M Amitrano
- Department of Pathology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA; Department of Microbiology and Immunology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA.
| | - Minsoo Kim
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA; Department of Pathology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA; Department of Microbiology and Immunology, University of Rochester Medical Center, Box 609, 601 Elmwood Ave., Rochester, NY 14642, USA.
| | - Andrew P Wojtovich
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA; Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Box 711/604, 575 Elmwood Ave., Rochester, NY 14642, USA.
| |
Collapse
|
13
|
Ferreira DJS, Pedroza AA, Braz GRF, Fernandes MP, Lagranha CJ. Mitochondrial dysfunction: maternal protein restriction as a trigger of reactive species overproduction and brainstem energy failure in male offspring brainstem. Nutr Neurosci 2018; 22:778-788. [PMID: 29495951 DOI: 10.1080/1028415x.2018.1444543] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mitochondria are important organelles in eukaryotic organisms, wherein their capacity to produce energy vary among the tissues depending upon the amounts of oxygen consumed. Part of the oxygen consumed during ATP generation produces reactive oxygen species, which if not efficiently removed can trigger a systemic damage to molecular compounds characterized as oxidative stress. Several studies have demonstrated that mitochondrial dysfunction and oxidative stress in the central nervous system (CNS) are related to a plethora of neural disorders. Herein, we hypothesize that a late autonomic imbalance-induced hypertension might be related to long-lasting effects of protein restriction during the critical period of the CNS development on the mitochondrial function and oxidative stress in the brainstem of adult (i.e. 150 days of age) male Wistar rats. Maternal protein restriction was induced by offering a diet based on 8% of casein from first day of pregnancy until weaning, when the male pups started to receive laboratory chow up to 150 days of life. The protein restriction induced an extended detrimental modulation in mitochondria function, decreasing the phosphorylation capacity with concomitant decrease in the mitochondrial membrane potential, wherein the reactive species overproduction triggered a disruption in proton conductance, which may gradually compromise mitochondria energy conservation. Interestingly, the elevated activity of glutathione-S-transferase and the augmented expression of uncoupling protein 2 are likely protective mechanisms induced by lipid peroxidation products, being feasible molecular changes attempting to deal with oxidative stress-induced ageing.
Collapse
Affiliation(s)
- D J S Ferreira
- Neuropsychiatry and Behavior Science Program, Federal University of Pernambuco , Recife , Brazil.,Laboratory of Biochemistry and Exercise Biochemistry, Department of Physical Education and Sports Science, Federal University of Pernambuco-CAV , Vitória de Santo Antão , Brazil
| | - A A Pedroza
- Laboratory of Biochemistry and Exercise Biochemistry, Department of Physical Education and Sports Science, Federal University of Pernambuco-CAV , Vitória de Santo Antão , Brazil
| | - G R F Braz
- Laboratory of Biochemistry and Exercise Biochemistry, Department of Physical Education and Sports Science, Federal University of Pernambuco-CAV , Vitória de Santo Antão , Brazil
| | - M P Fernandes
- Laboratory of Biochemistry and Exercise Biochemistry, Department of Physical Education and Sports Science, Federal University of Pernambuco-CAV , Vitória de Santo Antão , Brazil
| | - C J Lagranha
- Neuropsychiatry and Behavior Science Program, Federal University of Pernambuco , Recife , Brazil.,Laboratory of Biochemistry and Exercise Biochemistry, Department of Physical Education and Sports Science, Federal University of Pernambuco-CAV , Vitória de Santo Antão , Brazil
| |
Collapse
|
14
|
Zhang C, Jiang H, Wang P, Liu H, Sun X. Transcription factor NF-kappa B represses ANT1 transcription and leads to mitochondrial dysfunctions. Sci Rep 2017; 7:44708. [PMID: 28317877 PMCID: PMC5357787 DOI: 10.1038/srep44708] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 02/13/2017] [Indexed: 02/01/2023] Open
Abstract
Mitochondria are intracellular organelles involved in cell survival and death, and dysfunctions of mitochondria are related to neurodegenerative diseases. As the most abundant protein in the mitochondrial inner membrane, adenine nucleotide translocator 1 (ANT1) plays a critical role in mitochondrial function, including the exchange of adenosine triphosphate/adenosine diphosphate (ATP/ADP) in mitochondria, basal proton leak and mitochondrial permeability transition pore (mPTP). Here, we show that ANT1 transcription is regulated by transcription factor NF-kappa B (NF-κB). NF-κB is bound to two NF-κB responsive elements (NREs) located at +1 to +20 bp and +41 to +61 bp in the ANT1 promoter. An NF-κB signalling stimulator, tumour necrosis factor alpha (TNFα), suppresses ANT1 mRNA and protein expression. Activation of NF-κB by TNFα impairs ATP/ADP exchange and decreases ATP production in mitochondria. Activation of NF-κB by TNFα decreases calcium induced mPTP opening, elevates mitochondrial potential and increases reactive oxygen species (ROS) production in both T98G human glioblastoma cells and rat cortical neurons. These results demonstrate that NF-κB signalling may repress ANT1 gene transcription and impair mitochondrial functions.
Collapse
Affiliation(s)
- Chen Zhang
- Department of Neurology, Qilu Hospital of Shandong University, No. 107 West Wenhua Road, Jinan, 250012, Shandong Province, China
| | - Hui Jiang
- Department of Pediatrics, 2nd Hospital of Shandong University, No. 44 West Wenhua Road, Jinan, 250011, Shandong Province, China
| | - Pin Wang
- Otolaryngology Key, Lab of Ministry of Health, No. 44 West Wenhua Road, Jinan, China
| | - Heng Liu
- Otolaryngology Key, Lab of Ministry of Health, No. 44 West Wenhua Road, Jinan, China
| | - Xiulian Sun
- Brain Research Institute, Qilu Hospital of Shandong University, No.107 West Wenhua Road, Jinan, 250012, Shandong Province, China
| |
Collapse
|
15
|
Crichton PG, Lee Y, Kunji ERS. The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism. Biochimie 2017; 134:35-50. [PMID: 28057583 PMCID: PMC5395090 DOI: 10.1016/j.biochi.2016.12.016] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 12/24/2016] [Indexed: 12/14/2022]
Abstract
Uncoupling protein 1 (UCP1) is an integral membrane protein found in the mitochondrial inner membrane of brown adipose tissue, and facilitates the process of non-shivering thermogenesis in mammals. Its activation by fatty acids, which overcomes its inhibition by purine nucleotides, leads to an increase in the proton conductance of the inner mitochondrial membrane, short-circuiting the mitochondrion to produce heat rather than ATP. Despite 40 years of intense research, the underlying molecular mechanism of UCP1 is still under debate. The protein belongs to the mitochondrial carrier family of transporters, which have recently been shown to utilise a domain-based alternating-access mechanism, cycling between a cytoplasmic and matrix state to transport metabolites across the inner membrane. Here, we review the protein properties of UCP1 and compare them to those of mitochondrial carriers. UCP1 has the same structural fold as other mitochondrial carriers and, in contrast to past claims, is a monomer, binding one purine nucleotide and three cardiolipin molecules tightly. The protein has a single substrate binding site, which is similar to those of the dicarboxylate and oxoglutarate carriers, but also contains a proton binding site and several hydrophobic residues. As found in other mitochondrial carriers, UCP1 has two conserved salt bridge networks on either side of the central cavity, which regulate access to the substrate binding site in an alternating way. The conserved domain structures and mobile inter-domain interfaces are consistent with an alternating access mechanism too. In conclusion, UCP1 has retained all of the key features of mitochondrial carriers, indicating that it operates by a conventional carrier-like mechanism.
Collapse
Affiliation(s)
- Paul G Crichton
- Biomedical Research Centre, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom.
| | - Yang Lee
- Laboratory of Molecular Biology, Medical Research Council, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
| | - Edmund R S Kunji
- Mitochondrial Biology Unit, Medical Research Council, Cambridge Biomedical Campus, Wellcome Trust, MRC Building, Hills Road, Cambridge CB2 0XY, United Kingdom.
| |
Collapse
|
16
|
The conserved regulation of mitochondrial uncoupling proteins: From unicellular eukaryotes to mammals. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1858:21-33. [PMID: 27751905 DOI: 10.1016/j.bbabio.2016.10.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 09/29/2016] [Accepted: 10/13/2016] [Indexed: 12/19/2022]
Abstract
Uncoupling proteins (UCPs) belong to the mitochondrial anion carrier protein family and mediate regulated proton leak across the inner mitochondrial membrane. Free fatty acids, aldehydes such as hydroxynonenal, and retinoids activate UCPs. However, there are some controversies about the effective action of retinoids and aldehydes alone; thus, only free fatty acids are commonly accepted positive effectors of UCPs. Purine nucleotides such as GTP inhibit UCP-mediated mitochondrial proton leak. In turn, membranous coenzyme Q may play a role as a redox state-dependent metabolic sensor that modulates the complete activation/inhibition of UCPs. Such regulation has been observed for UCPs in microorganisms, plant and animal UCP1 homologues, and UCP1 in mammalian brown adipose tissue. The origin of UCPs is still under debate, but UCP homologues have been identified in all systematic groups of eukaryotes. Despite the differing levels of amino acid/DNA sequence similarities, functional studies in unicellular and multicellular organisms, from amoebae to mammals, suggest that the mechanistic regulation of UCP activity is evolutionarily well conserved. This review focuses on the regulatory feedback loops of UCPs involving free fatty acids, aldehydes, retinoids, purine nucleotides, and coenzyme Q (particularly its reduction level), which may derive from the early stages of evolution as UCP first emerged.
Collapse
|
17
|
Lee CP, Millar AH. The Plant Mitochondrial Transportome: Balancing Metabolic Demands with Energetic Constraints. TRENDS IN PLANT SCIENCE 2016; 21:662-676. [PMID: 27162080 DOI: 10.1016/j.tplants.2016.04.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 03/25/2016] [Accepted: 04/04/2016] [Indexed: 06/05/2023]
Abstract
In plants, mitochondrial function is associated with hundreds of metabolic reactions. To facilitate these reactions, charged substrates and cofactors move across the charge-impermeable inner mitochondrial membrane via specialized transporters and must work cooperatively with the electrochemical gradient which is essential for mitochondrial function. The regulatory framework for mitochondrial metabolite transport is expected to be more complex in plants than in mammals owing to the close metabolic association between mitochondrial, plastids, and peroxisome metabolism, as well as to the major diurnal fluctuations in plant metabolic function. We propose here how recent advances can be integrated towards defining the mitochondrial transportome in plants. We also discuss what this reveals about sustaining cooperativity between bioenergetics, metabolism, and transport in typical and challenging environments.
Collapse
Affiliation(s)
- Chun Pong Lee
- Australian Reseach Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia
| | - A Harvey Millar
- Australian Reseach Council (ARC) Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Australia.
| |
Collapse
|
18
|
Breitzig M, Bhimineni C, Lockey R, Kolliputi N. 4-Hydroxy-2-nonenal: a critical target in oxidative stress? Am J Physiol Cell Physiol 2016; 311:C537-C543. [PMID: 27385721 DOI: 10.1152/ajpcell.00101.2016] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 07/05/2016] [Indexed: 12/22/2022]
Abstract
In this perspective, we summarize and discuss critical advancements in the study of 4-hydroxy-2-nonenal (4-HNE) as it relates to diseases and clinical complications either caused or exacerbated by oxidative stress. Since its identification in 1980, 4-HNE has been extensively studied with an emphasis on its formation, its role in pathology, and its targets. As a reactive aldehyde, and a product of lipid peroxidation, studies corroborate its ability to disrupt signal transduction and protein activity, as well as induce inflammation and trigger cellular apoptosis in conditions of oxidative stress. Notably, we discuss the role of natural enzymes involved in the regulation of 4-HNE, and how they can be applied to its detoxification in various physiological conditions.
Collapse
Affiliation(s)
- Mason Breitzig
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Charishma Bhimineni
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Richard Lockey
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Narasaiah Kolliputi
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| |
Collapse
|
19
|
Adakeeva SI, Dubinin MV, Samartsev VN. Malonate as an inhibitor of cyclosporine A-sensitive calcium-independent free oxidation in liver mitochondria induced by fatty acids. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2015. [DOI: 10.1134/s199074781501002x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
20
|
Uncoupling protein 1 binds one nucleotide per monomer and is stabilized by tightly bound cardiolipin. Proc Natl Acad Sci U S A 2015; 112:6973-8. [PMID: 26038550 DOI: 10.1073/pnas.1503833112] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Uncoupling protein 1 (UCP1) catalyzes fatty acid-activated, purine nucleotide-sensitive proton leak across the mitochondrial inner membrane of brown adipose tissue to produce heat, and could help combat obesity and metabolic disease in humans. Studies over the last 30 years conclude that the protein is a dimer, binding one nucleotide molecule per two proteins, and unlike the related mitochondrial ADP/ATP carrier, does not bind cardiolipin. Here, we have developed novel methods to purify milligram amounts of UCP1 from native sources by using covalent chromatography that, unlike past methods, allows the protein to be prepared in defined conditions, free of excess detergent and lipid. Assessment of purified preparations by TLC reveal that UCP1 retains tightly bound cardiolipin, with a lipid phosphorus content equating to three molecules per protein, like the ADP/ATP carrier. Cardiolipin stabilizes UCP1, as demonstrated by reconstitution experiments and thermostability assays, indicating that the lipid has an integral role in the functioning of the protein, similar to other mitochondrial carriers. Furthermore, we find that UCP1 is not dimeric but monomeric, as indicated by size exclusion analysis, and has a ligand titration profile in isothermal calorimetric measurements that clearly shows that one nucleotide binds per monomer. These findings reveal the fundamental composition of UCP1, which is essential for understanding the mechanism of the protein. Our assessment of the properties of UCP1 indicate that it is not unique among mitochondrial carriers and so is likely to use a common exchange mechanism in its primary function in brown adipose tissue mitochondria.
Collapse
|
21
|
Effects of standardized extract of Ginkgo biloba leaves EGb761 on mitochondrial functions: mechanism(s) of action and dependence on the source of mitochondria and respiratory substrate. J Bioenerg Biomembr 2014; 46:493-501. [DOI: 10.1007/s10863-014-9590-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 11/05/2014] [Indexed: 12/19/2022]
|
22
|
Different effects of guanine nucleotides (GDP and GTP) on protein-mediated mitochondrial proton leak. PLoS One 2014; 9:e98969. [PMID: 24904988 PMCID: PMC4056835 DOI: 10.1371/journal.pone.0098969] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 05/08/2014] [Indexed: 11/19/2022] Open
Abstract
In this study, we compared the influence of GDP and GTP on isolated mitochondria respiring under conditions favoring oxidative phosphorylation (OXPHOS) and under conditions excluding this process, i.e., in the presence of carboxyatractyloside, an adenine nucleotide translocase inhibitor, and/or oligomycin, an FOF1-ATP synthase inhibitor. Using mitochondria isolated from rat kidney and human endothelial cells, we found that the action of GDP and GTP can differ diametrically depending on the conditions. Namely, under conditions favoring OXPHOS, both in the absence and presence of linoleic acid, an activator of uncoupling proteins (UCPs), the addition of 1 mM GDP resulted in the state 4 (non-phosphorylating respiration)-state 3 (phosphorylating respiration) transition, which is characteristic of ADP oxidative phosphorylation. In contrast, the addition of 1 mM GTP resulted in a decrease in the respiratory rate and an increase in the membrane potential, which is characteristic of UCP inhibition. The stimulatory effect of GDP, but not GTP, was also observed in inside-out submitochondrial particles prepared from rat kidney mitochondria. However, the effects of GDP and GTP were more similar in the presence of OXPHOS inhibitors. The importance of these observations in connection with the action of UCPs, adenine nucleotide translocase (or other carboxyatractyloside-sensitive carriers), carboxyatractyloside- and purine nucleotide-insensitive carriers, as well as nucleoside-diphosphate kinase (NDPK) are considered. Because the measurements favoring oxidative phosphorylation better reflect in vivo conditions, our study strongly supports the idea that GDP cannot be considered a significant physiological inhibitor of UCP. Moreover, it appears that, under native conditions, GTP functions as a more efficient UCP inhibitor than GDP and ATP.
Collapse
|
23
|
Rogers C, Davis B, Neufer PD, Murphy MP, Anderson EJ, Robidoux J. A transient increase in lipid peroxidation primes preadipocytes for delayed mitochondrial inner membrane permeabilization and ATP depletion during prolonged exposure to fatty acids. Free Radic Biol Med 2014; 67:330-41. [PMID: 24269897 PMCID: PMC3935619 DOI: 10.1016/j.freeradbiomed.2013.11.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Revised: 10/29/2013] [Accepted: 11/12/2013] [Indexed: 12/22/2022]
Abstract
Preadipocytes are periodically subjected to fatty acid (FA) concentrations that are potentially cytotoxic. We tested the hypothesis that prolonged exposure of preadipocytes of human origin to a physiologically relevant mix of FAs leads to mitochondrial inner membrane (MIM) permeabilization and ultimately to mitochondrial crisis. We found that exposure of preadipocytes to FAs led to progressive cyclosporin A-sensitive MIM permeabilization, which in turn caused a reduction in MIM potential, oxygen consumption, and ATP synthetic capacity and, ultimately, death. Additionally, we showed that FAs induce a transient increase in intramitochondrial reactive oxygen species (ROS) and lipid peroxide production, lasting roughly 30 and 120min for the ROS and lipid peroxides, respectively. MIM permeabilization and its deleterious consequences including mitochondrial crisis and cell death were prevented by treating the cells with the mitochondrial FA uptake inhibitor etomoxir, the mitochondrion-selective superoxide and lipid peroxide antioxidants MitoTempo and MitoQ, or the lipid peroxide and reactive carbonyl scavenger l-carnosine. FAs also promoted a delayed oxidative stress phase. However, the beneficial effects of etomoxir, MitoTempo, and l-carnosine were lost by delaying the treatment by 2h, suggesting that the initial phase was sufficient to prime the cells for the delayed MIM permeabilization and mitochondrial crisis. It also suggested that the second ROS production phase is a consequence of this loss in mitochondrial health. Altogether, our data suggest that approaches designed to diminish intramitochondrial ROS or lipid peroxide accumulation, as well as MIM permeabilization, are valid mechanism-based therapeutic avenues to prevent the loss in preadipocyte metabolic fitness associated with prolonged exposure to elevated FA levels.
Collapse
Affiliation(s)
- Carlyle Rogers
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834, USA
| | - Barbara Davis
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834, USA
| | - P Darrell Neufer
- Department of Physiology, East Carolina University, Greenville, NC 27834, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
| | - Michael P Murphy
- MRC Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Cambridge CB2 0XY, UK
| | - Ethan J Anderson
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834, USA; Department of Kinesiology, East Carolina University, Greenville, NC 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA
| | - Jacques Robidoux
- Department of Pharmacology and Toxicology, East Carolina University, Greenville, NC 27834, USA; East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC 27834, USA.
| |
Collapse
|
24
|
|
25
|
Malingriaux EA, Rupprecht A, Gille L, Jovanovic O, Jezek P, Jaburek M, Pohl EE. Fatty acids are key in 4-hydroxy-2-nonenal-mediated activation of uncoupling proteins 1 and 2. PLoS One 2013; 8:e77786. [PMID: 24204965 PMCID: PMC3810126 DOI: 10.1371/journal.pone.0077786] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 09/12/2013] [Indexed: 11/19/2022] Open
Abstract
The production of reactive oxygen species (ROS) in mitochondria is very sensitive to the proton motive force and may be decreased by mild uncoupling, mediated e.g. by mitochondrial uncoupling proteins (UCPs). UCPs were conversely hypothesized to be activated by ROS. Conclusions from experiments studying the reactive product of lipid peroxidation 4-hydroxy-2-nonenal (HNE) in isolated mitochondria and UCP knock-out mice are highly controversial. Here we investigated the molecular mechanism of HNE action by evaluating the separate contributions of lipid and protein phases of the membrane and by comparing UCP1 and UCP2, which were reconstituted in planar lipid bilayers. We demonstrated that aldehyde does not directly activate either UCP1 or UCP2. However, HNE strongly potentiated the membrane conductance increase (Gm) mediated by different long-chain fatty acids in UCP-containing and in UCP-free membranes and this suggest the involvement of both lipid-mediated and protein-mediated mechanisms with FA playing the central role. Gm increase was concentration-dependent and exhibited a typical saturation kinetic with the binding constant 0.3 mM. By using Electron Paramagnetic Resonance, membrane fluidity change could be excluded as a cause for the HNE-mediated increase in the presence of FA. The impact of the HNE binding to definite positively charged UCP amino acid residues is discussed as a possible protein-mediated mechanism of the UCP activation.
Collapse
Affiliation(s)
- Elena A. Malingriaux
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Anne Rupprecht
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Lars Gille
- Institute of Pharmacology and Toxicology, University of Veterinary Medicine, Vienna, Austria
| | - Olga Jovanovic
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
| | - Petr Jezek
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Jaburek
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Elena E. Pohl
- Institute of Physiology, Pathophysiology and Biophysics, University of Veterinary Medicine, Vienna, Austria
- * E-mail:
| |
Collapse
|
26
|
Mailloux RJ, McBride SL, Harper ME. Unearthing the secrets of mitochondrial ROS and glutathione in bioenergetics. Trends Biochem Sci 2013; 38:592-602. [PMID: 24120033 DOI: 10.1016/j.tibs.2013.09.001] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/04/2013] [Accepted: 09/05/2013] [Indexed: 01/06/2023]
Abstract
During the cellular oxidation of fuels, electrons are used to power the proton pumps of the mitochondrial electron transport chain (ETC) and ultimately drive ATP synthesis and the reduction of molecular oxygen to water. During these oxidative processes, some electrons can 'spin off' during fuel oxidation and electron transport to univalently reduce O2, forming reactive oxygen species (ROS). In excess, ROS can be detrimental; however, at low concentrations oxyradicals are essential signaling molecules. Mitochondria thus use a battery of systems to finely control types and levels of ROS, including antioxidants. Several antioxidant systems depend on glutathione. Here, we review mitochondrial ROS homeostatic systems, including emerging knowledge about roles of glutathione in redox balance and the control of protein function by post-translational modification.
Collapse
Affiliation(s)
- Ryan J Mailloux
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | | | | |
Collapse
|
27
|
Huang Q, Wang H, Perry SW, Figueiredo-Pereira ME. Negative regulation of 26S proteasome stability via calpain-mediated cleavage of Rpn10 subunit upon mitochondrial dysfunction in neurons. J Biol Chem 2013; 288:12161-74. [PMID: 23508964 PMCID: PMC3636900 DOI: 10.1074/jbc.m113.464552] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Indexed: 12/15/2022] Open
Abstract
Proteasomal and mitochondrial dysfunctions are implicated in chronic neurodegenerative diseases. To investigate the impact of mitochondrial impairment on the proteasome, we treated rat cerebral cortical neurons with oligomycin, antimycin, or rotenone, which inhibit different elements of the electron transport chain. Firstly, we observed a reduction in ubiquitinated proteins and E1 activity. Secondly, we established that 26S proteasomes are disassembled with a decline in activity. Thirdly, we show, to our knowledge for the first time, that calpain activation triggers the selective processing of the 26S proteasome subunit Rpn10. Other proteasome subunits tested were not affected. Calpain also cleaved caspase 3 to an inactive fragment, thus preventing apoptosis that is an energy-dependent cell death pathway. In addition, calpain cleaved the microtubule-associated protein Tau, a major component of neurofibrillary tangles in Alzheimer disease and other tauopathies. Fourthly, we detected a rise in 20S proteasome levels and activity. Finally, we show that both acute (16 h) and long term (up to 7 days) mitochondrial impairment led to down-regulation of ubiquitinated-proteins, 26S proteasome disassembly, and a rise in 20S proteasomes. We postulate that upon mitochondrial dysfunction, ATP depletion and calpain activation contribute to the demise of protein turnover by the ubiquitin/proteasome pathway. The concomitant rise in 20S proteasomes, which seem to degrade proteins in an unregulated and energy-independent manner, in the short term may carry out the turnover of randomly unfolded oxidized proteins. However, if chronic, it could lead to neurodegeneration as regulated protein degradation by the ubiquitin/proteasome pathway is essential for neuronal survival.
Collapse
Affiliation(s)
- Qian Huang
- From the Department of Biological Sciences, Hunter College and
Graduate Center, City University of New York, New York, New York 10065 and
| | - Hu Wang
- From the Department of Biological Sciences, Hunter College and
Graduate Center, City University of New York, New York, New York 10065 and
| | - Seth W. Perry
- the Department of Biomedical Engineering, University of
Rochester, Rochester, New York 14627
| | - Maria E. Figueiredo-Pereira
- From the Department of Biological Sciences, Hunter College and
Graduate Center, City University of New York, New York, New York 10065 and
| |
Collapse
|
28
|
Mailloux RJ, Xuan JY, Beauchamp B, Jui L, Lou M, Harper ME. Glutaredoxin-2 is required to control proton leak through uncoupling protein-3. J Biol Chem 2013; 288:8365-8379. [PMID: 23335511 DOI: 10.1074/jbc.m112.442905] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Glutathionylation has emerged as a key modification required for controlling protein function in response to changes in cell redox status. Recently, we showed that the glutathionylation state of uncoupling protein-3 (UCP3) modulates the leak of protons back into the mitochondrial matrix, thus controlling reactive oxygen species production. However, whether or not UCP3 glutathionylation is mediated enzymatically has remained unknown because previous work relied on the use of pharmacological agents, such as diamide, to alter the UCP3 glutathionylation state. Here, we demonstrate that glutaredoxin-2 (Grx2), a matrix oxidoreductase, is required to glutathionylate and inhibit UCP3. Analysis of bioenergetics in skeletal muscle mitochondria revealed that knock-out of Grx2 (Grx2(-/-)) increased proton leak in a UCP3-dependent manner. These effects were reversed using diamide, a glutathionylation catalyst. Importantly, the increased leak did not compromise coupled respiration. Knockdown of Grx2 augmented proton leak-dependent respiration in primary myotubes from wild type mice, an effect that was absent in UCP3(-/-) cells. These results confirm that Grx2 deactivates UCP3 by glutathionylation. To our knowledge, this is the first enzyme identified to regulate UCP3 by glutathionylation and is the first study on the role of Grx2 in the regulation of energy metabolism.
Collapse
Affiliation(s)
- Ryan J Mailloux
- Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Jian Ying Xuan
- Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Brittany Beauchamp
- Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Linda Jui
- Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Marjorie Lou
- Center of Redox Biology and School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, Nebraska 68583
| | - Mary-Ellen Harper
- Department of Biochemistry, Immunology, and Microbiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada.
| |
Collapse
|
29
|
High efficiency versus maximal performance--the cause of oxidative stress in eukaryotes: a hypothesis. Mitochondrion 2012. [PMID: 23178790 DOI: 10.1016/j.mito.2012.11.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Degenerative diseases are in part based on elevated production of ROS (reactive oxygen species) in mitochondria, mainly during stress and excessive work under stress (strenuous exercise). The production of ROS increases with increasing mitochondrial membrane potential (ΔΨ(m)). A mechanism is described which is suggested to keep ΔΨ(m) at low values under normal conditions thus preventing ROS formation, but is switched off under stress and excessive work to maximize the rate of ATP synthesis, accompanied by decreased efficiency. Low ΔΨ(m) and low ROS production are suggested to occur by inhibition of respiration at high [ATP]/[ADP] ratios. The nucleotides interact with phosphorylated cytochrome c oxidase (COX), representing the step with the highest flux-control coefficient of mitochondrial respiration. At stress and excessive work neural signals are suggested to dephosphorylate the enzyme and abolish the control of COX activity (respiration) by the [ATP]/[ADP] ratio with consequent increase of ΔΨ(m) and ROS production. The control of COX by the [ATP]/[ADP] ratio, in addition, is proposed to increase the efficiency of ATP production via a third proton pumping pathway, identified in eukaryotic but not in prokaryotic COX. We conclude that 'oxidative stress' occurs when the control of COX activity by the [ATP]/[ADP] ratio is switched off via neural signals.
Collapse
|
30
|
Woyda-Ploszczyca AM, Jarmuszkiewicz W. Hydroxynonenal, a lipid peroxidation end product, stimulates uncoupling protein activity in Acanthamoeba castellanii mitochondria; the sensitivity of the inducible activity to purine nucleotides depends on the membranous ubiquinone redox state. J Bioenerg Biomembr 2012; 44:525-38. [PMID: 22798183 DOI: 10.1007/s10863-012-9456-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Accepted: 06/19/2012] [Indexed: 01/06/2023]
Abstract
We studied the influence of exogenously generated superoxide and exogenous 4-hydroxy-2-nonenal (HNE), a lipid peroxidation end product, on the activity of the Acanthamoeba castellanii uncoupling protein (AcUCP). The superoxide-generating xanthine/xanthine oxidase system was insufficient to induce mitochondrial uncoupling. In contrast, exogenously added HNE induced GTP-sensitive AcUCP-mediated mitochondrial uncoupling. In non-phosphorylating mitochondria, AcUCP activation by HNE was demonstrated by increased oxygen consumption accompanied by a decreased membrane potential and ubiquinone (Q) reduction level. The HNE-induced GTP-sensitive proton conductance was similar to that observed with linoleic acid. In phosphorylating mitochondria, the HNE-induced AcUCP-mediated uncoupling decreased the yield of oxidative phosphorylation. We demonstrated that the efficiency of GTP to inhibit HNE-induced AcUCP-mediated uncoupling was regulated by the endogenous Q redox state. A high Q reduction level activated AcUCP by relieving the inhibition caused by GTP while a low Q reduction level favoured the inhibition. We propose that the regulation of UCP activity involves a rapid response through the endogenous Q redox state that modulates the inhibition of UCP by purine nucleotides, followed by a late response through lipid peroxidation products resulting from an increase in the formation of reactive oxygen species that modulate the UCP activation.
Collapse
|
31
|
Friederich-Persson M, Aslam S, Nordquist L, Welch WJ, Wilcox CS, Palm F. Acute knockdown of uncoupling protein-2 increases uncoupling via the adenine nucleotide transporter and decreases oxidative stress in diabetic kidneys. PLoS One 2012; 7:e39635. [PMID: 22768304 PMCID: PMC3388100 DOI: 10.1371/journal.pone.0039635] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 05/25/2012] [Indexed: 11/18/2022] Open
Abstract
Increased O2 metabolism resulting in chronic hypoxia is common in models of endstage renal disease. Mitochondrial uncoupling increases O2 consumption but the ensuing reduction in mitochondrial membrane potential may limit excessive oxidative stress. The present study addressed the hypothesis that mitochondrial uncoupling regulates mitochondria function and oxidative stress in the diabetic kidney. Isolated mitochondria from kidney cortex of control and streptozotocin-induced diabetic rats were studied before and after siRNA knockdown of uncoupling protein-2 (UCP-2). Diabetes resulted in increased UCP-2 protein expression and UCP-2-mediated uncoupling, but normal mitochondria membrane potential. This uncoupling was inhibited by GDP, which also increased the membrane potential. siRNA reduced UCP-2 protein expression in controls and diabetics (−30–50%), but paradoxically further increased uncoupling and markedly reduced the membrane potential. This siRNA mediated uncoupling was unaffected by GDP but was blocked by ADP and carboxyatractylate (CAT). Mitochondria membrane potential after UCP-2 siRNA was unaffected by GDP but increased by CAT. This demonstrated that further increased mitochondria uncoupling after siRNA towards UCP-2 is mediated through the adenine nucleotide transporter (ANT). The increased oxidative stress in the diabetic kidney, manifested as increased thiobarbituric acids, was reduced by knocking down UCP-2 whereas whole-body oxidative stress, manifested as increased circulating malondialdehyde, remained unaffected. All parameters investigated were unaffected by scrambled siRNA. In conclusion, mitochondrial uncoupling via UCP-2 regulates mitochondria membrane potential in diabetes. However, blockade of the diabetes-induced upregulation of UCP- 2 results in excessive uncoupling and reduced oxidative stress in the kidney via activation of ANT.
Collapse
Affiliation(s)
- Malou Friederich-Persson
- Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
| | | | | | | | | | | |
Collapse
|
32
|
Schmitz JPJ, Jeneson JAL, van Oorschot JWM, Prompers JJ, Nicolay K, Hilbers PAJ, van Riel NAW. Prediction of muscle energy states at low metabolic rates requires feedback control of mitochondrial respiratory chain activity by inorganic phosphate. PLoS One 2012; 7:e34118. [PMID: 22470528 PMCID: PMC3314597 DOI: 10.1371/journal.pone.0034118] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 02/22/2012] [Indexed: 01/20/2023] Open
Abstract
The regulation of the 100-fold dynamic range of mitochondrial ATP synthesis flux in skeletal muscle was investigated. Hypotheses of key control mechanisms were included in a biophysical model of oxidative phosphorylation and tested against metabolite dynamics recorded by (31)P nuclear magnetic resonance spectroscopy ((31)P MRS). Simulations of the initial model featuring only ADP and Pi feedback control of flux failed in reproducing the experimentally sampled relation between myoplasmic free energy of ATP hydrolysis (ΔG(p) = ΔG(p)(o')+RT ln ([ADP][Pi]/[ATP]) and the rate of mitochondrial ATP synthesis at low fluxes (<0.2 mM/s). Model analyses including Monte Carlo simulation approaches and metabolic control analysis (MCA) showed that this problem could not be amended by model re-parameterization, but instead required reformulation of ADP and Pi feedback control or introduction of additional control mechanisms (feed forward activation), specifically at respiratory Complex III. Both hypotheses were implemented and tested against time course data of phosphocreatine (PCr), Pi and ATP dynamics during post-exercise recovery and validation data obtained by (31)P MRS of sedentary subjects and track athletes. The results rejected the hypothesis of regulation by feed forward activation. Instead, it was concluded that feedback control of respiratory chain complexes by inorganic phosphate is essential to explain the regulation of mitochondrial ATP synthesis flux in skeletal muscle throughout its full dynamic range.
Collapse
Affiliation(s)
- Joep P J Schmitz
- BioModeling and Bioinformatics, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
33
|
Chowdhury SKR, Smith DR, Fernyhough P. The role of aberrant mitochondrial bioenergetics in diabetic neuropathy. Neurobiol Dis 2012; 51:56-65. [PMID: 22446165 DOI: 10.1016/j.nbd.2012.03.016] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 02/22/2012] [Accepted: 03/01/2012] [Indexed: 02/07/2023] Open
Abstract
Diabetic neuropathy is a neurological complication of diabetes that causes significant morbidity and, because of the obesity-driven rise in incidence of type 2 diabetes, is becoming a major international health problem. Mitochondrial phenotype is abnormal in sensory neurons in diabetes and may contribute to the etiology of diabetic neuropathy where a distal dying-back neurodegenerative process is a key component contributing to fiber loss. This review summarizes the major features of mitochondrial dysfunction in neurons and Schwann cells in human diabetic patients and in experimental animal models (primarily exhibiting type 1 diabetes). This article attempts to relate these findings to the development of critical neuropathological hallmarks of the disease. Recent work reveals that hyperglycemia in diabetes triggers nutrient excess in neurons that, in turn, mediates a phenotypic change in mitochondrial biology through alteration of the AMP-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) signaling axis. This vital energy sensing metabolic pathway modulates mitochondrial function, biogenesis and regeneration. The bioenergetic phenotype of mitochondria in diabetic neurons is aberrant due to deleterious alterations in expression and activity of respiratory chain components as a direct consequence of abnormal AMPK/PGC-1α signaling. Utilization of innovative respirometry equipment to analyze mitochondrial function of cultured adult sensory neurons from diabetic rodents shows that the outcome for cellular bioenergetics is a reduced adaptability to fluctuations in ATP demand. The diabetes-induced maladaptive process is hypothesized to result in exhaustion of the ATP supply in the distal nerve compartment and induction of nerve fiber dissolution. The role of mitochondrial dysfunction in the etiology of diabetic neuropathy is compared with other types of neuropathy with a distal dying-back pathology such as Friedreich ataxia, Charcot-Marie-Tooth disease type 2 and human immunodeficiency virus-associated distal-symmetric neuropathy.
Collapse
Affiliation(s)
- Subir K Roy Chowdhury
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, MB, Canada
| | | | | |
Collapse
|
34
|
Akude E, Zherebitskaya E, Chowdhury SKR, Smith DR, Dobrowsky RT, Fernyhough P. Diminished superoxide generation is associated with respiratory chain dysfunction and changes in the mitochondrial proteome of sensory neurons from diabetic rats. Diabetes 2011; 60:288-97. [PMID: 20876714 PMCID: PMC3012184 DOI: 10.2337/db10-0818] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Impairments in mitochondrial function have been proposed to play a role in the etiology of diabetic sensory neuropathy. We tested the hypothesis that mitochondrial dysfunction in axons of sensory neurons in type 1 diabetes is due to abnormal activity of the respiratory chain and an altered mitochondrial proteome. RESEARCH DESIGN AND METHODS Proteomic analysis using stable isotope labeling with amino acids in cell culture (SILAC) determined expression of proteins in mitochondria from dorsal root ganglia (DRG) of control, 22-week-old streptozotocin (STZ)-diabetic rats, and diabetic rats treated with insulin. Rates of oxygen consumption and complex activities in mitochondria from DRG were measured. Fluorescence imaging of axons of cultured sensory neurons determined the effect of diabetes on mitochondrial polarization status, oxidative stress, and mitochondrial matrix-specific reactive oxygen species (ROS). RESULTS Proteins associated with mitochondrial dysfunction, oxidative phosphorylation, ubiquinone biosynthesis, and the citric acid cycle were downregulated in diabetic samples. For example, cytochrome c oxidase subunit IV (COX IV; a complex IV protein) and NADH dehydrogenase Fe-S protein 3 (NDUFS3; a complex I protein) were reduced by 29 and 36% (P < 0.05), respectively, in diabetes and confirmed previous Western blot studies. Respiration and mitochondrial complex activity was significantly decreased by 15 to 32% compared with control. The axons of diabetic neurons exhibited oxidative stress and depolarized mitochondria, an aberrant adaption to oligomycin-induced mitochondrial membrane hyperpolarization, but reduced levels of intramitochondrial superoxide compared with control. CONCLUSIONS Abnormal mitochondrial function correlated with a downregulation of mitochondrial proteins, with components of the respiratory chain targeted in lumbar DRG in diabetes. The reduced activity of the respiratory chain was associated with diminished superoxide generation within the mitochondrial matrix and did not contribute to oxidative stress in axons of diabetic neurons. Alternative pathways involving polyol pathway activity appear to contribute to raised ROS in axons of diabetic neurons under high glucose concentration.
Collapse
Affiliation(s)
- Eli Akude
- St. Boniface Hospital Research Centre, Winnipeg, Manitoba, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | | | - Darrell R. Smith
- St. Boniface Hospital Research Centre, Winnipeg, Manitoba, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Rick T. Dobrowsky
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, Kansas
| | - Paul Fernyhough
- St. Boniface Hospital Research Centre, Winnipeg, Manitoba, Canada
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
- Corresponding author: Paul Fernyhough,
| |
Collapse
|
35
|
Brenner C, Subramaniam K, Pertuiset C, Pervaiz S. Adenine nucleotide translocase family: four isoforms for apoptosis modulation in cancer. Oncogene 2010; 30:883-95. [PMID: 21076465 DOI: 10.1038/onc.2010.501] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Mitochondria have important functions in mammalian cells as the energy powerhouse and integrators of the mitochondrial pathway of apoptosis. The adenine nucleotide translocase (ANT) is a family of proteins involved in cell death pathways that perform distinctly opposite functions to regulate cell fate decisions. On the one hand, ANT catalyzes the adenosine triphosphate export from the mitochondrial matrix to the intermembrane space with the concomitant import of ADP from the intermembrane space to the matrix. On the other hand, during periods of stress, ANT could function as a lethal pore and trigger the process of mitochondrial membrane permeabilization, which leads irreversibly to cell death. In human, ANT is encoded by four homologous genes, whose expression is not only tissue specific, but also varies according to the pathophysiological state of the cell. Recent evidence revealed a differential role of the ANT isoforms in apoptosis and a deregulation of their expression in cancer. In this review, we introduce the current knowledge of ANT in apoptosis and cancer cells and propose a novel classification of ANT isoforms.
Collapse
Affiliation(s)
- C Brenner
- Univ Paris-Sud, Châtenay-Malabry, France.
| | | | | | | |
Collapse
|
36
|
Samartsev VN, Kozhina OV. Acetoacetate as regulator of palmitic acid-induced uncoupling involving liver mitochondrial ADP/ATP antiporter and aspartate/glutamate antiporter. BIOCHEMISTRY (MOSCOW) 2010; 75:598-605. [PMID: 20632939 DOI: 10.1134/s0006297910050093] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The effect of acetoacetate on palmitate-induced uncoupling with the involvement of ADP/ATP antiporter and aspartate/glutamate antiporter has been studied in liver mitochondria. The incubation of mitochondria with acetoacetate during succinate oxidation in the presence of rotenone, oligomycin, and EGTA suppresses the accumulation of conjugated dienes. This is considered as a display of antioxidant effect of acetoacetate. Under these conditions, acetoacetate does not influence the respiration of mitochondria in the absence or presence of palmitate but eliminates the ability of carboxyatractylate or aspartate separately to suppress the uncoupling effect of this fatty acid. The action of acetoacetate is eliminated by beta-hydroxybutyrate or thiourea, but not by the antioxidant Trolox. In the absence of acetoacetate, the palmitate-induced uncoupling is limited by a stage sensitive to carboxyatractylate (ADP/ATP antiporter) or aspartate (aspartate/glutamate antiporter); in its presence, it is limited by a stage insensitive to the effect of these agents. In the presence of Trolox, ADP suppresses the uncoupling action of palmitate to the same degree as carboxyatractylate. Under these conditions, acetoacetate eliminates the recoupling effects of ADP and aspartate, including their joint action. This effect of acetoacetate is eliminated by beta-hydroxybutyrate or thiourea. It is supposed that the stimulating effect of acetoacetate is caused both by increase in the rate of transfer of fatty acid anion from the inner monolayer of the membrane to the outer one, which involves the ADP/ATP antiporter and aspartate/glutamate antiporter, and by elimination of the ability of ADP to inhibit this transport. Under conditions of excessive production of reactive oxygen species in mitochondria at a high membrane potential and in the presence of small amounts of fatty acids, such effect of acetoacetate can be considered as one of the mechanisms of antioxidant protection.
Collapse
|
37
|
Abstract
The mitochondrion is the most important organelle in determining continued cell survival and cell death. Mitochondrial dysfunction leads to many human maladies, including cardiovascular diseases, neurodegenerative disease, and cancer. These mitochondria-related pathologies range from early infancy to senescence. The central premise of this review is that if mitochondrial abnormalities contribute to the pathological state, alleviating the mitochondrial dysfunction would contribute to attenuating the severity or progression of the disease. Therefore, this review will examine the role of mitochondria in the etiology and progression of several diseases and explore potential therapeutic benefits of targeting mitochondria in mitigating the disease processes. Indeed, recent advances in mitochondrial biology have led to selective targeting of drugs designed to modulate and manipulate mitochondrial function and genomics for therapeutic benefit. These approaches to treat mitochondrial dysfunction rationally could lead to selective protection of cells in different tissues and various disease states. However, most of these approaches are in their infancy.
Collapse
|
38
|
Mookerjee SA, Divakaruni AS, Jastroch M, Brand MD. Mitochondrial uncoupling and lifespan. Mech Ageing Dev 2010; 131:463-72. [PMID: 20363244 PMCID: PMC2924931 DOI: 10.1016/j.mad.2010.03.010] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Revised: 03/17/2010] [Accepted: 03/29/2010] [Indexed: 12/21/2022]
Abstract
The quest to understand why we age has given rise to numerous lines of investigation that have gradually converged to include metabolic control by mitochondrial activity as a major player. That is, the ideal balance between nutrient uptake, its transduction into usable energy, and the mitigation of damaging byproducts can be regulated by mitochondrial respiration and output (ATP, reactive oxygen species (ROS), and heat). Mitochondrial inefficiency through proton leak, which uncouples substrate oxidation from ADP phosphorylation, can comprise as much as 30% of the basal metabolic rate. This uncoupling is hypothesized to protect cells from conditions that favor ROS production. Uncoupling can also occur through pharmacological induction of proton leak and activity of the uncoupling proteins. Mitochondrial uncoupling is implicated in lifespan extension through its effects on metabolic rate and ROS production. However, evidence to date does not suggest a consistent role for uncoupling in lifespan. The purpose of this review is to discuss recent work examining how mitochondrial uncoupling impacts lifespan.
Collapse
|
39
|
Aguirre E, Cadenas S. GDP and carboxyatractylate inhibit 4-hydroxynonenal-activated proton conductance to differing degrees in mitochondria from skeletal muscle and heart. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1716-26. [PMID: 20599679 DOI: 10.1016/j.bbabio.2010.06.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 06/15/2010] [Accepted: 06/19/2010] [Indexed: 12/17/2022]
Abstract
The lipid peroxidation product 4-hydroxynonenal (HNE) increases the proton conductance of the inner mitochondrial membrane through effects on uncoupling proteins (UCPs) and the adenine nucleotide translocase (ANT); however, the relative contribution of the two carriers to these effects is unclear. To clarify this we isolated mitochondria from skeletal muscle and heart of wild-type and Ucp3 knockout (Ucp3KO) mice. To increase UCP3 expression, some mice were i.p. injected with LPS (12mg/kg body weight). In spite of the increased UCP3 expression levels, basal proton conductance did not change. HNE increased the proton conductance of skeletal muscle and heart mitochondria. In skeletal muscle, this increase was lower in Ucp3KO mice and higher in LPS-treated wild-type mice, and was partially abolished by GDP (UCPs inhibitor) and completely abolished by carboxyatractylate (ANT inhibitor) or addition of both inhibitors. GDP had no effect on HNE-induced conductance in heart mitochondria, but carboxyatractylate or administration of both inhibitors had a partial effect. GDP-mediated inhibition of HNE-activated proton conductance in skeletal muscle mitochondria was not observed in Ucp3KO mice, indicating that GDP is specific for UCP3, at least in muscle. Carboxyatractylate was able to inhibit UCP3, probably through an indirect mechanism. Our results are consistent with the conclusion that, in skeletal muscle, HNE-induced increase in proton conductance is mediated by UCP3 (30%) and ANT, whereas in the heart the increase is mediated by ANT and other carriers, possibly including UCP3.
Collapse
Affiliation(s)
- Enara Aguirre
- Department of Regenerative Cardiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | | |
Collapse
|
40
|
Lagranha CJ, Deschamps A, Aponte A, Steenbergen C, Murphy E. Sex differences in the phosphorylation of mitochondrial proteins result in reduced production of reactive oxygen species and cardioprotection in females. Circ Res 2010; 106:1681-91. [PMID: 20413785 DOI: 10.1161/circresaha.109.213645] [Citation(s) in RCA: 230] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Although premenopausal females have a lower risk for cardiovascular disease, the mechanism(s) are poorly understood. OBJECTIVE We tested the hypothesis that cardioprotection in females is mediated by altered mitochondrial protein levels and/or posttranslational modifications. METHODS AND RESULTS Using both an in vivo and an isolated heart model of ischemia and reperfusion (I/R), we found that females had less injury than males. Using proteomic methods we found that female hearts had increased phosphorylation and activity of aldehyde dehydrogenase (ALDH)2, an enzyme that detoxifies reactive oxygen species (ROS)-generated aldehyde adducts, and that an activator of ALDH2 reduced I/R injury in males but had no significant effect in females. Wortmannin, an inhibitor of phosphatidylinositol 3-kinase, blocked the protection and the increased phosphorylation of ALDH2 in females, but had no effect in males. Furthermore, we found an increase in phosphorylation of alpha-ketoglutarate dehydrogenase (alphaKGDH) in female hearts. alphaKGDH is a major source of ROS generation particularly with a high NADH/NAD ratio which occurs during I/R. We found decreased ROS generation in permeabilized female mitochondria given alphaKGDH substrates and NADH, suggesting that increased phosphorylation of alphaKGDH might reduce ROS generation by alphaKGDH. In support of this hypothesis, we found that protein kinase C-dependent phosphorylation of purified alphaKGDH reduced ROS generation. Additionally, myocytes from female hearts had less ROS generation following I/R than males and addition of wortmannin increased ROS generation in females to the same levels as in males. CONCLUSIONS These data suggest that posttranslational modifications can modify ROS handling and play an important role in female cardioprotection.
Collapse
Affiliation(s)
- Claudia J Lagranha
- Translational Medicine Branch, NHLBI-NIH 10 Center Bethesda, MD 20892, USA
| | | | | | | | | |
Collapse
|
41
|
Azzu V, Brand MD. The on-off switches of the mitochondrial uncoupling proteins. Trends Biochem Sci 2009; 35:298-307. [PMID: 20006514 DOI: 10.1016/j.tibs.2009.11.001] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2009] [Revised: 11/04/2009] [Accepted: 11/06/2009] [Indexed: 12/15/2022]
Abstract
Mitochondrial uncoupling proteins disengage substrate oxidation from ADP phosphorylation by dissipating the proton electrochemical gradient that is required for ATP synthesis. In doing this, the archetypal uncoupling protein, UCP1, mediates adaptive thermogenesis. By contrast, its paralogues UCP2 and UCP3 are not thought to mediate whole body thermogenesis in mammals. Instead, they have been implicated in a variety of physiological and pathological processes, including protection from oxidative stress, negative regulation of glucose sensing systems and the adaptation of fatty acid oxidation capacity to starving. Although much work has been devoted to how these proteins are activated, little is known of the mechanisms that reverse this activation.
Collapse
Affiliation(s)
- Vian Azzu
- MRC Mitochondrial Biology Unit, Cambridge CB2 0XY, UK.
| | | |
Collapse
|
42
|
Won JC, Park JY, Kim YM, Koh EH, Seol S, Jeon BH, Han J, Kim JR, Park TS, Choi CS, Lee WJ, Kim MS, Lee IK, Youn JH, Lee KU. Peroxisome proliferator-activated receptor-gamma coactivator 1-alpha overexpression prevents endothelial apoptosis by increasing ATP/ADP translocase activity. Arterioscler Thromb Vasc Biol 2009; 30:290-7. [PMID: 19965780 DOI: 10.1161/atvbaha.109.198721] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Fatty acids increase reactive oxygen species generation and cell apoptosis in endothelial cells. The peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1alpha) is a transcriptional coactivator that increases mitochondrial biogenesis and fatty acid oxidation in various cells. This study was undertaken to investigate the possible preventive effect of PGC-1alpha on endothelial apoptosis and its molecular mechanism. METHODS AND RESULTS Treatment with linoleic acid in cultured human aortic endothelial cells increased reactive oxygen species generation and cell apoptosis. These effects appeared to be mediated by increases in cytosolic fat metabolites, ie, fatty acyl CoA, diacylglycerol, and ceramide, and consequent decreases in ATP/ADP translocase activity of adenine nucleotide translocator. Adenoviral overexpression of PGC-1alpha prevented linoleic acid-induced increases in reactive oxygen species generation and cell apoptosis in human aortic endothelial cells by increasing fatty acid oxidation, decreasing diacylglycerol and ceramide, and increasing ATP/ADP translocase activity. In isolated aorta, PGC-1alpha overexpression prevented linoleic acid-induced decrease in endothelium-dependent vasorelaxation, and this effect was abolished by adenine nucleotide translocator1 shRNA. CONCLUSIONS PGC-1alpha regulates reactive oxygen species generation and apoptosis in endothelial cells by increasing fatty acid oxidation and enhancing ATP/ADP translocase activity. Measures to increase PGC-1alpha expression or ATP/ADP translocase activity in vascular cells may aid in the prevention or treatment of atherosclerosis.
Collapse
Affiliation(s)
- Jong Chul Won
- Department of Internal Medicine, University of Ulsan College of Medicine, Seoul, Korea
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Uncoupling protein-1 (UCP1) contributes to the basal proton conductance of brown adipose tissue mitochondria. J Bioenerg Biomembr 2009; 41:335-42. [PMID: 19705265 DOI: 10.1007/s10863-009-9232-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 08/02/2009] [Indexed: 01/21/2023]
Abstract
Proton leak pathways uncouple substrate oxidation from ATP synthesis in mitochondria. These pathways are classified as basal (not regulated) or inducible (activated and inhibited). Previously it was found that over half of the basal proton conductance of muscle mitochondria was catalyzed by the adenine nucleotide translocase (ANT), an abundant mitochondrial anion carrier protein. To determine whether ANT is the unique protein catalyst, or one of many proteins that catalyze basal proton conductance, we measured proton leak kinetics in mitochondria isolated from brown adipose tissue (BAT). BAT can express another mitochondrial anion carrier, UCP1, at concentrations similar to ANT. Basal proton conductance was measured under conditions where UCP1 and ANT were catalytically inactive and was found to be lower in mitochondria from UCP1 knockout mice compared to wild-type. Ablation of another abundant inner membrane protein, nicotinamide nucleotide transhydrogenase, had no effect on proton leak kinetics in mitochondria from liver, kidney or muscle, showing that basal proton conductance is not catalyzed by all membrane proteins. We identify UCP1 as a second protein propagating basal proton leak, lending support to the hypothesis that basal leak pathways are perpetrated by members of the mitochondrial anion carrier family but not by other mitochondrial inner membrane proteins.
Collapse
|
44
|
A novel kinetic assay of mitochondrial ATP-ADP exchange rate mediated by the ANT. Biophys J 2009; 96:2490-504. [PMID: 19289073 DOI: 10.1016/j.bpj.2008.12.3915] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Revised: 12/08/2008] [Accepted: 12/17/2008] [Indexed: 11/23/2022] Open
Abstract
A novel method exploiting the differential affinity of ADP and ATP to Mg(2+) was developed to measure mitochondrial ADP-ATP exchange rate. The rate of ATP appearing in the medium after addition of ADP to energized mitochondria, is calculated from the measured rate of change in free extramitochondrial [Mg(2+)] reported by the membrane-impermeable 5K(+) salt of the Mg(2+)-sensitive fluorescent indicator, Magnesium Green, using standard binding equations. The assay is designed such that the adenine nucleotide translocase (ANT) is the sole mediator of changes in [Mg(2+)] in the extramitochondrial volume, as a result of ADP-ATP exchange. We also provide data on the dependence of ATP efflux rate within the 6.8-7.8 matrix pH range as a function of membrane potential. Finally, by comparing the ATP-ADP steady-state exchange rate to the amount of the ANT in rat brain synaptic, brain nonsynaptic, heart and liver mitochondria, we provide molecular turnover numbers for the known ANT isotypes.
Collapse
|
45
|
Stowe DF, Camara AKS. Mitochondrial reactive oxygen species production in excitable cells: modulators of mitochondrial and cell function. Antioxid Redox Signal 2009; 11:1373-414. [PMID: 19187004 PMCID: PMC2842133 DOI: 10.1089/ars.2008.2331] [Citation(s) in RCA: 338] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 01/12/2009] [Accepted: 01/13/2009] [Indexed: 12/14/2022]
Abstract
The mitochondrion is a major source of reactive oxygen species (ROS). Superoxide (O(2)(*-)) is generated under specific bioenergetic conditions at several sites within the electron-transport system; most is converted to H(2)O(2) inside and outside the mitochondrial matrix by superoxide dismutases. H(2)O(2) is a major chemical messenger that, in low amounts and with its products, physiologically modulates cell function. The redox state and ROS scavengers largely control the emission (generation scavenging) of O(2)(*-). Cell ischemia, hypoxia, or toxins can result in excess O(2)(*-) production when the redox state is altered and the ROS scavenger systems are overwhelmed. Too much H(2)O(2) can combine with Fe(2+) complexes to form reactive ferryl species (e.g., Fe(IV) = O(*)). In the presence of nitric oxide (NO(*)), O(2)(*-) forms the reactant peroxynitrite (ONOO(-)), and ONOOH-induced nitrosylation of proteins, DNA, and lipids can modify their structure and function. An initial increase in ROS can cause an even greater increase in ROS and allow excess mitochondrial Ca(2+) entry, both of which are factors that induce cell apoptosis and necrosis. Approaches to reduce excess O(2)(*-) emission include selectively boosting the antioxidant capacity, uncoupling of oxidative phosphorylation to reduce generation of O(2)(*-) by inducing proton leak, and reversibly inhibiting electron transport. Mitochondrial cation channels and exchangers function to maintain matrix homeostasis and likely play a role in modulating mitochondrial function, in part by regulating O(2)(*-) generation. Cell-signaling pathways induced physiologically by ROS include effects on thiol groups and disulfide linkages to modify posttranslationally protein structure to activate/inactivate specific kinase/phosphatase pathways. Hypoxia-inducible factors that stimulate a cascade of gene transcription may be mediated physiologically by ROS. Our knowledge of the role played by ROS and their scavenging systems in modulation of cell function and cell death has grown exponentially over the past few years, but we are still limited in how to apply this knowledge to develop its full therapeutic potential.
Collapse
Affiliation(s)
- David F Stowe
- Anesthesiology Research Laboratories, Department of Anesthesiology, The Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
| | | |
Collapse
|