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Alarcón-Vila C, Insausti-Urkia N, Torres S, Segalés-Rovira P, Conde de la Rosa L, Nuñez S, Fucho R, Fernández-Checa JC, García-Ruiz C. Dietary and genetic disruption of hepatic methionine metabolism induce acid sphingomyelinase to promote steatohepatitis. Redox Biol 2023; 59:102596. [PMID: 36610223 PMCID: PMC9827379 DOI: 10.1016/j.redox.2022.102596] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023] Open
Abstract
Alcoholic (ASH) and nonalcoholic. (NASH).steatohepatitis are advanced.stages.of.fatty.liver.disease.Methionine adenosyltransferase 1A (MAT1A) plays a key role in hepatic methionine metabolism and germline Mat1a deletion in mice promotes NASH. Acid sphingomyelinase (ASMase) triggers hepatocellular apoptosis and liver fibrosis and has been shown to downregulate MAT1A expression in the context of fulminant liver failure. Given the role of ASMase in steatohepatitis development, we investigated the status of ASMase in Mat1a-/- mice and the regulation of ASMase by SAM/SAH. Consistent with its role in NASH, Mat1a-/- mice fed a choline-deficient (CD) diet exhibited macrosteatosis, inflammation, fibrosis and liver injury as well as reduced total and mitochondrial GSH levels. Our data uncovered an increased basal expression and activity of ASMase but not neutral SMase in Mat1a-/- mice, which further increased upon CD feeding. Interestingly, adenovirus-mediated shRNA expression targeting ASMase reduced ASMase activity and protected Mat1a-/- mice against CD diet-induced NASH. Similar results were observed in CD fed Mat1a-/- mice by pharmacological inhibition of ASMase with amitriptyline. Moreover, Mat1a/ASMase double knockout mice were resistant to CD-induced NASH. ASMase knockdown protected wild type mice against NASH induced by feeding a diet deficient in methionine and choline. Furthermore, Mat1a-/- mice developed acute-on-chronic ASH and this outcome was ameliorated by amitriptyline treatment. In vitro data in primary mouse hepatocytes revealed that decreased SAM/SAH ratio increased ASMase mRNA level and activity. MAT1A and ASMase mRNA levels exhibited an inverse correlation in liver samples from patients with ASH and NASH. Thus, disruption of methionine metabolism sensitizes to steatohepatitis by ASMase activation via decreased SAM/SAH. These findings imply that MAT1A deletion and ASMase activation engage in a self-sustained loop of relevance for steatohepatitis.
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Affiliation(s)
- Cristina Alarcón-Vila
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain
| | - Naroa Insausti-Urkia
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain
| | - Sandra Torres
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain
| | - Paula Segalés-Rovira
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain
| | - Laura Conde de la Rosa
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain
| | - Susana Nuñez
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain
| | - Raquel Fucho
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain
| | - Jose C Fernández-Checa
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain; University of Southern California Research Center for Liver Diseases, Keck School of Medicine, USC, Los Angeles, CA, USA.
| | - Carmen García-Ruiz
- Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Barcelona, Spain; Liver Unit, Hospital Clínic I Provincial, IDIBAPS, Barcelona, Spain; CIBERehd, University of Barcelona, Spain; University of Southern California Research Center for Liver Diseases, Keck School of Medicine, USC, Los Angeles, CA, USA.
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Hong CH, Ko MS, Kim JH, Cho H, Lee CH, Yoon JE, Yun JY, Baek IJ, Jang JE, Lee SE, Cho YK, Baek JY, Oh SJ, Lee BY, Lim JS, Lee J, Hartig SM, Conde de la Rosa L, Garcia-Ruiz C, Lee KU, Fernández-Checa JC, Choi JW, Kim S, Koh EH. Sphingosine 1-Phosphate Receptor 4 Promotes Nonalcoholic Steatohepatitis by Activating NLRP3 Inflammasome. Cell Mol Gastroenterol Hepatol 2021; 13:925-947. [PMID: 34890841 PMCID: PMC8810559 DOI: 10.1016/j.jcmgh.2021.12.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 12/02/2021] [Accepted: 12/02/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Sphingosine 1-phosphate receptors (S1PRs) are a group of G-protein-coupled receptors that confer a broad range of functional effects in chronic inflammatory and metabolic diseases. S1PRs also may mediate the development of nonalcoholic steatohepatitis (NASH), but the specific subtypes involved and the mechanism of action are unclear. METHODS We investigated which type of S1PR isoforms is activated in various murine models of NASH. The mechanism of action of S1PR4 was examined in hepatic macrophages isolated from high-fat, high-cholesterol diet (HFHCD)-fed mice. We developed a selective S1PR4 functional antagonist by screening the fingolimod (2-amino-2-[2-(4- n -octylphenyl)ethyl]-1,3- propanediol hydrochloride)-like sphingolipid-focused library. RESULTS The livers of various mouse models of NASH as well as hepatic macrophages showed high expression of S1pr4. Moreover, in a cohort of NASH patients, expression of S1PR4 was 6-fold higher than those of healthy controls. S1pr4+/- mice were protected from HFHCD-induced NASH and hepatic fibrosis without changes in steatosis. S1pr4 depletion in hepatic macrophages inhibited lipopolysaccharide-mediated Ca++ release and deactivated the Nod-like receptor pyrin domain-containning protein 3 (NLRP3) inflammasome. S1P increased the expression of S1pr4 in hepatic macrophages and activated NLRP3 inflammasome through inositol trisphosphate/inositol trisphosphate-receptor-dependent [Ca++] signaling. To further clarify the biological function of S1PR4, we developed SLB736, a novel selective functional antagonist of SIPR4. Similar to S1pr4+/- mice, administration of SLB736 to HFHCD-fed mice prevented the development of NASH and hepatic fibrosis, but not steatosis, by deactivating the NLRP3 inflammasome. CONCLUSIONS S1PR4 may be a new therapeutic target for NASH that mediates the activation of NLRP3 inflammasome in hepatic macrophages.
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Affiliation(s)
- Chung Hwan Hong
- Department of Medical Science, Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Myoung Seok Ko
- Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jae Hyun Kim
- College of Pharmacy, Seoul National University, Seoul, Korea,College of Pharmacy, Kangwon National University, Chuncheon, Korea
| | - Hyunkyung Cho
- College of Pharmacy, Seoul National University, Seoul, Korea
| | - Chi-Ho Lee
- College of Pharmacy, Gachon University, Incheon, Korea
| | - Ji Eun Yoon
- Department of Medical Science, Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Ji-Young Yun
- Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - In-Jeoung Baek
- Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea,Department of Convergence Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jung Eun Jang
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Seung Eun Lee
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Yun Kyung Cho
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Ji Yeon Baek
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Soo Jin Oh
- New Drug Development Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | | | - Joon Seo Lim
- Clinical Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jongkook Lee
- College of Pharmacy, Kangwon National University, Chuncheon, Korea
| | - Sean M. Hartig
- Molecular and Cellular Biology, Division of Diabetes, Endocrinology, and Metabolism, Baylor College of Medicine, Houston, Texas
| | - Laura Conde de la Rosa
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona and Liver Unit-Hospital Clinic-Instituto de Investigaciones Biomédicas August Pi i Sunyer, Centro de Investigación Biomédica en Red, Barcelona, Spain
| | - Carmen Garcia-Ruiz
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona and Liver Unit-Hospital Clinic-Instituto de Investigaciones Biomédicas August Pi i Sunyer, Centro de Investigación Biomédica en Red, Barcelona, Spain,Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Ki-Up Lee
- Department of Convergence Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Jose C. Fernández-Checa
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona and Liver Unit-Hospital Clinic-Instituto de Investigaciones Biomédicas August Pi i Sunyer, Centro de Investigación Biomédica en Red, Barcelona, Spain,Research Center for Alcoholic Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine, University of Southern California, Los Angeles, California,Correspondence Address correspondence to: Jose C. Fernández-Checa, PhD, Department of Cell Death and Proliferation, Instituto Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Cientificas, Barcelona and Liver Unit-Hospital Clinic–Instituto de Investigaciones Biomédicas August Pi i Sunyer, Centro de Investigación Biomédica en Red, Barcelona 08036, Spain. fax: (34) 93-3129405.
| | - Ji Woong Choi
- College of Pharmacy, Gachon University, Incheon, Korea,Ji Woong Choi, PhD, Laboratory of Pharmacology, College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Korea. fax: (82) 32-820-4829.
| | - Sanghee Kim
- College of Pharmacy, Seoul National University, Seoul, Korea,Sanghee Kim, PhD, College of Pharmacy, Seoul National University, Gwanak-ro, Gwanak-gu, Seoul 08826, Korea. fax: (82) 2-762-8322.
| | - Eun Hee Koh
- Biomedical Research Center, Asan Institute for Life Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea,Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea,Eun Hee Koh, MD, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 05505, Korea. fax: (82) 2-3010-6962.
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Torres S, Baulies A, Insausti-Urkia N, Alarcón-Vila C, Fucho R, Solsona-Vilarrasa E, Núñez S, Robles D, Ribas V, Wakefield L, Grompe M, Lucena MI, Andrade RJ, Win S, Aung TA, Kaplowitz N, García-Ruiz C, Fernández-Checa JC. Endoplasmic Reticulum Stress-Induced Upregulation of STARD1 Promotes Acetaminophen-Induced Acute Liver Failure. Gastroenterology 2019; 157:552-568. [PMID: 31029706 DOI: 10.1053/j.gastro.2019.04.023] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 04/11/2019] [Accepted: 04/20/2019] [Indexed: 01/14/2023]
Abstract
BACKGROUND & AIMS Acetaminophen (APAP) overdose is a major cause of acute liver failure (ALF). Mitochondrial SH3BP5 (also called SAB) and phosphorylation of c-Jun N-terminal kinase (JNK) mediate the hepatotoxic effects of APAP. We investigated the involvement of steroidogenic acute regulatory protein (STARD1), a mitochondrial cholesterol transporter, in this process and sensitization by valproic acid (VPA), which depletes glutathione and stimulates steroidogenesis. METHODS Nonfasted C57BL/6J mice (control) and mice with liver-specific deletion of STARD1 (Stard1ΔHep), SAB (SabΔHep), or JNK1 and JNK2 (Jnk1+2ΔHep) were given VPA with or without APAP. Liver tissues were collected and analyzed by histology and immunohistochemistry and for APAP metabolism, endoplasmic reticulum (ER) stress, and mitochondrial function. Adult human hepatocytes were transplanted into Fah-/-/Rag2-/-/Il2rg-/-/NOD (FRGN) mice to create mice with humanized livers. RESULTS Administration of VPA before administration of APAP increased the severity of liver damage in control mice. The combination of VPA and APAP increased expression of CYP2E1, formation of NAPQI-protein adducts, and depletion of glutathione from liver tissues of control mice, resulting in ER stress and the upregulation of STARD1. Livers from control mice given VPA and APAP accumulated cholesterol in the mitochondria and had sustained mitochondrial depletion of glutathione and mitochondrial dysfunction. Inhibition of ER stress, by administration of tauroursodeoxycholic acid to control mice, prevented upregulation of STARD1 in liver and protected the mice from hepatoxicity following administration of VPA and APAP. Administration of N-acetylcysteine to control mice prevented VPA- and APAP-induced ER stress and liver injury. Stard1ΔHep mice were resistant to induction of ALF by VPA and APAP, despite increased mitochondrial levels of glutathione and phosphorylated JNK; we made similar observations in fasted Stard1ΔHep mice given APAP alone. SabΔHep mice or Jnk1+2ΔHep mice did not develop ALF following administration of VPA and APAP. The ability of VPA to increase the severity of APAP-induced liver damage was observed in FRGN mice with humanized liver. CONCLUSIONS In studies of mice, we found that upregulation of STARD1 following ER stress mediates APAP hepatoxicity via SH3BP5 and phosphorylation of JNK1 and JNK2.
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Affiliation(s)
- Sandra Torres
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | - Anna Baulies
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | - Naroa Insausti-Urkia
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | - Cristina Alarcón-Vila
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | - Raquel Fucho
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | - Estel Solsona-Vilarrasa
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | - Susana Núñez
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | - David Robles
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | - Vicent Ribas
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain
| | | | - Markus Grompe
- Oregon Health and Science University, Portland, Oregon
| | - M Isabel Lucena
- Unidad de Gestión Clínica de Aparato Digestivo, Servicio de Farmacología Clínica, Instituto de Investigación Biomédica de Málaga-IBIMA, CIBEREHD, Hospital Universitario Virgen de la Victoria, Universidad de Málaga, Málaga, Spain
| | - Raul J Andrade
- Unidad de Gestión Clínica de Aparato Digestivo, Servicio de Farmacología Clínica, Instituto de Investigación Biomédica de Málaga-IBIMA, CIBEREHD, Hospital Universitario Virgen de la Victoria, Universidad de Málaga, Málaga, Spain
| | - Sanda Win
- USC Research Center for Liver Disease, USC Keck School of Medicine, Los Angeles, California
| | - Tin A Aung
- USC Research Center for Liver Disease, USC Keck School of Medicine, Los Angeles, California
| | - Neil Kaplowitz
- USC Research Center for Liver Disease, USC Keck School of Medicine, Los Angeles, California
| | - Carmen García-Ruiz
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain; USC Research Center for ALPD, Keck School of Medicine, Los Angeles, California
| | - Jose C Fernández-Checa
- Cell Death and Proliferation, IIBB-CSIC, Barcelona, Spain; Liver Unit, Hospital Cínic, IDIBAPS and CIBEREHD, Barcelona, Spain; USC Research Center for ALPD, Keck School of Medicine, Los Angeles, California.
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Barbero-Camps E, Roca-Agujetas V, Bartolessis I, de Dios C, Fernández-Checa JC, Marí M, Morales A, Hartmann T, Colell A. Cholesterol impairs autophagy-mediated clearance of amyloid beta while promoting its secretion. Autophagy 2018; 14:1129-1154. [PMID: 29862881 PMCID: PMC6103708 DOI: 10.1080/15548627.2018.1438807] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Macroautophagy/autophagy failure with the accumulation of autophagosomes is an early neuropathological feature of Alzheimer disease (AD) that directly affects amyloid beta (Aβ) metabolism. Although loss of presenilin 1 function has been reported to impair lysosomal function and prevent autophagy flux, the detailed mechanism leading to autophagy dysfunction in AD remains to be elucidated. The resemblance between pathological hallmarks of AD and Niemann-Pick Type C disease, including endosome-lysosome abnormalities and impaired autophagy, suggests cholesterol accumulation as a common link. Using a mouse model of AD (APP-PSEN1-SREBF2 mice), expressing chimeric mouse-human amyloid precursor protein with the familial Alzheimer Swedish mutation (APP695swe) and mutant presenilin 1 (PSEN1-dE9), together with a dominant-positive, truncated and active form of SREBF2/SREBP2 (sterol regulatory element binding factor 2), we demonstrated that high brain cholesterol enhanced autophagosome formation, but disrupted its fusion with endosomal-lysosomal vesicles. The combination of these alterations resulted in impaired degradation of Aβ and endogenous MAPT (microtubule associated protein tau), and stimulated autophagy-dependent Aβ secretion. Exacerbated Aβ-induced oxidative stress in APP-PSEN1-SREBF2 mice, due to cholesterol-mediated depletion of mitochondrial glutathione/mGSH, is critical for autophagy induction. In agreement, in vivo mitochondrial GSH recovery with GSH ethyl ester, inhibited autophagosome synthesis by preventing the oxidative inhibition of ATG4B deconjugation activity exerted by Aβ. Moreover, cholesterol-enrichment within the endosomes-lysosomes modified the levels and membrane distribution of RAB7A and SNAP receptors (SNAREs), which affected its fusogenic ability. Accordingly, in vivo treatment with 2-hydroxypropyl-β-cyclodextrin completely rescued these alterations, making it a potential therapeutic tool for AD.
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Affiliation(s)
- Elisabet Barbero-Camps
- a Department of Cell Death and Proliferation , Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain
| | - Vicente Roca-Agujetas
- a Department of Cell Death and Proliferation , Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain
| | - Isabel Bartolessis
- a Department of Cell Death and Proliferation , Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain
| | - Cristina de Dios
- a Department of Cell Death and Proliferation , Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain.,c Departament de Biomedicina, Facultat de Medicina , Universitat de Barcelona , Barcelona , Spain
| | - Jose C Fernández-Checa
- a Department of Cell Death and Proliferation , Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain.,d Liver Unit , Hospital Clinic, CIBEREHD , Barcelona , Spain , Research Center for Alcoholic Liver and Pancreatic Diseases , Keck School of Medicine of the University of Southern California , Los Angeles , CA , USA
| | - Montserrat Marí
- a Department of Cell Death and Proliferation , Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain
| | - Albert Morales
- a Department of Cell Death and Proliferation , Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain
| | - Tobias Hartmann
- e Experimental Neurology , Saarland University , Homburg/Saar , Germany
| | - Anna Colell
- a Department of Cell Death and Proliferation , Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) , Barcelona , Spain.,b Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED) , Spain
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Abstract
Mitochondria are considered cholesterol-poor organelles, and obtain their cholesterol load by the action of specialized proteins involved in its delivery from extramitochondrial sources and trafficking within mitochondrial membranes. Although mitochondrial cholesterol fulfills vital physiological functions, such as the synthesis of bile acids in the liver or the formation of steroid hormones in specialized tissues, recent evidence indicates that the accumulation of cholesterol in mitochondria may be a key event in prevalent human diseases, in particular in the development of steatohepatitis (SH) and its progression to hepatocellular carcinoma (HCC). Mitochondrial cholesterol accumulation promotes the transition from simple steatosis to SH due to the sensitization to oxidative stress and cell death. However, mitochondrial cholesterol loading in HCC determines apoptosis resistance and insensitivity to chemotherapy. These opposing functions of mitochondrial cholesterol in SH and HCC define its paradoxical role in cell death as a pro- and anti-apoptotic factor. Further understanding of this conundrum may be useful to modulate the progression from SH to HCC by targeting mitochondrial cholesterol trafficking.
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Affiliation(s)
- Carmen García-Ruiz
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, C/Rosello 161, 08036, Barcelona, Spain
- Liver Unit, Hospital Clinic, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
- Keck School of Medicine, USC, University of Southern California Research Center for Alcohol Liver and Pancreatic Diseases and Cirrhosis, Los Angeles, CA, USA
| | - Vicente Ribas
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, C/Rosello 161, 08036, Barcelona, Spain
- Liver Unit, Hospital Clinic, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Anna Baulies
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, C/Rosello 161, 08036, Barcelona, Spain
- Liver Unit, Hospital Clinic, IDIBAPS, Barcelona, Spain
- Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Jose C Fernández-Checa
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, C/Rosello 161, 08036, Barcelona, Spain.
- Liver Unit, Hospital Clinic, IDIBAPS, Barcelona, Spain.
- Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain.
- Keck School of Medicine, USC, University of Southern California Research Center for Alcohol Liver and Pancreatic Diseases and Cirrhosis, Los Angeles, CA, USA.
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Baulies A, Ribas V, Núñez S, Torres S, Alarcón-Vila C, Martínez L, Suda J, Ybanez MD, Kaplowitz N, García-Ruiz C, Fernández-Checa JC. Lysosomal Cholesterol Accumulation Sensitizes To Acetaminophen Hepatotoxicity by Impairing Mitophagy. Sci Rep 2015; 5:18017. [PMID: 26657973 PMCID: PMC4676017 DOI: 10.1038/srep18017] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 11/10/2015] [Indexed: 01/04/2023] Open
Abstract
The role of lysosomes in acetaminophen (APAP) hepatotoxicity is poorly understood. Here, we investigated the impact of genetic and drug-induced lysosomal cholesterol (LC) accumulation in APAP hepatotoxicity. Acid sphingomyelinase (ASMase)−/− mice exhibit LC accumulation and higher mortality after APAP overdose compared to ASMase+/+ littermates. ASMase−/− hepatocytes display lower threshold for APAP-induced cell death and defective fusion of mitochondria-containing autophagosomes with lysosomes, which decreased mitochondrial quality control. LC accumulation in ASMase+/+ hepatocytes caused by U18666A reproduces the susceptibility of ASMase−/− hepatocytes to APAP and the impairment in the formation of mitochondria-containing autolysosomes. LC extraction by 25-hydroxycholesterol increased APAP-mediated mitophagy and protected ASMase−/− mice and hepatocytes against APAP hepatotoxicity, effects that were reversed by chloroquine to disrupt autophagy. The regulation of LC by U18666A or 25-hydroxycholesterol did not affect total cellular sphingomyelin content or its lysosomal distribution. Of relevance, amitriptyline-induced ASMase inhibition in human hepatocytes caused LC accumulation, impaired mitophagy and increased susceptibility to APAP. Similar results were observed upon glucocerebrosidase inhibition by conduritol β-epoxide, a cellular model of Gaucher disease. These findings indicate that LC accumulation determines susceptibility to APAP hepatotoxicity by modulating mitophagy, and imply that genetic or drug-mediated ASMase disruption sensitizes to APAP-induced liver injury.
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Affiliation(s)
- Anna Baulies
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, Barcelona, and Liver Unit-Hospital Clinic-IDIBAPS.,Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Vicent Ribas
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, Barcelona, and Liver Unit-Hospital Clinic-IDIBAPS.,Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Susana Núñez
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, Barcelona, and Liver Unit-Hospital Clinic-IDIBAPS.,Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Sandra Torres
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, Barcelona, and Liver Unit-Hospital Clinic-IDIBAPS.,Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Cristina Alarcón-Vila
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, Barcelona, and Liver Unit-Hospital Clinic-IDIBAPS.,Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Laura Martínez
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, Barcelona, and Liver Unit-Hospital Clinic-IDIBAPS.,Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain
| | - Jo Suda
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California Research Center for Liver Diseases, University of Southern California, Los Angeles, CA 90089-9121, USA
| | - Maria D Ybanez
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California Research Center for Liver Diseases, University of Southern California, Los Angeles, CA 90089-9121, USA
| | - Neil Kaplowitz
- Division of Gastrointestinal and Liver Diseases, Keck School of Medicine, University of Southern California Research Center for Liver Diseases, University of Southern California, Los Angeles, CA 90089-9121, USA
| | - Carmen García-Ruiz
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, Barcelona, and Liver Unit-Hospital Clinic-IDIBAPS.,Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain.,University of Southern California Research Center for Alcohol Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine, USC, Los Angeles, CA, USA
| | - Jose C Fernández-Checa
- Department of Cell Death and Proliferation, Instituto Investigaciones Biomedicas de Barcelona, CSIC, Barcelona, and Liver Unit-Hospital Clinic-IDIBAPS.,Centro de Investigación Biomédica en Red (CIBERehd), Barcelona, Spain.,University of Southern California Research Center for Alcohol Liver and Pancreatic Diseases and Cirrhosis, Keck School of Medicine, USC, Los Angeles, CA, USA
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7
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Marí M, Morales A, Colell A, García-Ruiz C, Fernández-Checa JC. Mitochondrial cholesterol accumulation in alcoholic liver disease: Role of ASMase and endoplasmic reticulum stress. Redox Biol 2014; 3:100-8. [PMID: 25453982 PMCID: PMC4297930 DOI: 10.1016/j.redox.2014.09.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 09/21/2014] [Accepted: 09/23/2014] [Indexed: 02/08/2023] Open
Abstract
Alcoholic liver disease (ALD) is a major cause of chronic liver disease and a growing health concern in theworld. While the pathogenesis of ALD is poorly characterized key players identified in experimental models and patients, such as perturbations in mitochondrial structure and function, selective loss of antioxidant defense and susceptibility to inflammatory cytokines, contribute to ALD progression. Both oxidative stress and mitochondrial dysfunction compromise essential cellular functions and energy generation and hence are important pathogenic mechanisms of ALD. An important process mediating the mitochondrial disruption induced by alcohol intake is the trafficking of cholesterol to mitochondria, mediated by acid sphingomyelinase-induced endoplasmic reticulum stress, which contributes to increased cholesterol synthesis and StARD1upregulation. Mitochondrial cholesterol accumulation not only sensitizes to oxidative stress but it can contribute to the metabolic reprogramming in ALD, manifested by activation of the hypoxia inducible transcription factor 1 and stimulation of glycolysis and lactate secretion. Thus, a better understanding of the mechanisms underlying alcohol-mediated mitochondrial impairment and oxidative stress may lead to the identification of novel treatments for ALD. The present review briefly summarizes current knowledge on the cellular and molecular mechanisms contributing to alcohol-induced mitochondrial dysfunction and cholesterol accumulation and provides insights for potential therapeutic targets in ALD. Alcohol perturbs mitochondria function, which modulates ROS generation and alcohol metabolism. Alcohol stimulates mitochondrial cholesterol (mChol) accumulation. MChol accumulation impairs mitochondrial function and mediates alcohol-induced lipotoxicity. ASMase promotes mitochondrial dysfunction by stimulating mChol loading.
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Affiliation(s)
- Montserrat Marí
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain.
| | - Albert Morales
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain
| | - Anna Colell
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain
| | - Carmen García-Ruiz
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain
| | - Jose C Fernández-Checa
- Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB-CSIC), Consejo Superior Investigaciones Científicas (CSIC), IDIBAPS, Liver Unit-Hospital Clínic, CIBEREHD, 08036 Barcelona, Spain; Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
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8
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Barbero-Camps E, Fernández A, Baulies A, Martinez L, Fernández-Checa JC, Colell A. Endoplasmic reticulum stress mediates amyloid β neurotoxicity via mitochondrial cholesterol trafficking. Am J Pathol 2014; 184:2066-81. [PMID: 24815354 DOI: 10.1016/j.ajpath.2014.03.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 03/04/2014] [Accepted: 03/18/2014] [Indexed: 01/28/2023]
Abstract
Disrupted cholesterol homeostasis has been reported in Alzheimer disease and is thought to contribute to disease progression by promoting amyloid β (Aβ) accumulation. In particular, mitochondrial cholesterol enrichment has been shown to sensitize to Aβ-induced neurotoxicity. However, the molecular mechanisms responsible for the increased cholesterol levels and its trafficking to mitochondria in Alzheimer disease remain poorly understood. Here, we show that endoplasmic reticulum (ER) stress triggered by Aβ promotes cholesterol synthesis and mitochondrial cholesterol influx, resulting in mitochondrial glutathione (mGSH) depletion in older age amyloid precursor protein/presenilin-1 (APP/PS1) mice. Mitochondrial cholesterol accumulation was associated with increased expression of mitochondrial-associated ER membrane proteins, which favor cholesterol translocation from ER to mitochondria along with specific cholesterol carriers, particularly the steroidogenic acute regulatory protein. In vivo treatment with the ER stress inhibitor 4-phenylbutyric acid prevented mitochondrial cholesterol loading and mGSH depletion, thereby protecting APP/PS1 mice against Aβ-induced neurotoxicity. Similar protection was observed with GSH ethyl ester administration, which replenishes mGSH without affecting the unfolded protein response, thus positioning mGSH depletion downstream of ER stress. Overall, these results indicate that Aβ-mediated ER stress and increased mitochondrial cholesterol trafficking contribute to the pathologic progression observed in old APP/PS1 mice, and that ER stress inhibitors may be explored as therapeutic agents for Alzheimer disease.
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Affiliation(s)
- Elisabet Barbero-Camps
- Department of Cell Death and Proliferation, Biomedical Research Institute of Barcelona - Higher Council for Scientific Research (IIBB-CSIC), Barcelona, Spain; Liver Unit, Hospital Clinic, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), the Center for Biomedical Research in Hepatic and Digestive Diseases (CIBEREHD), Barcelona, Spain
| | - Anna Fernández
- Department of Cell Death and Proliferation, Biomedical Research Institute of Barcelona - Higher Council for Scientific Research (IIBB-CSIC), Barcelona, Spain; Liver Unit, Hospital Clinic, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), the Center for Biomedical Research in Hepatic and Digestive Diseases (CIBEREHD), Barcelona, Spain.
| | - Anna Baulies
- Department of Cell Death and Proliferation, Biomedical Research Institute of Barcelona - Higher Council for Scientific Research (IIBB-CSIC), Barcelona, Spain; Liver Unit, Hospital Clinic, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), the Center for Biomedical Research in Hepatic and Digestive Diseases (CIBEREHD), Barcelona, Spain
| | - Laura Martinez
- Department of Cell Death and Proliferation, Biomedical Research Institute of Barcelona - Higher Council for Scientific Research (IIBB-CSIC), Barcelona, Spain; Liver Unit, Hospital Clinic, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), the Center for Biomedical Research in Hepatic and Digestive Diseases (CIBEREHD), Barcelona, Spain
| | - Jose C Fernández-Checa
- Department of Cell Death and Proliferation, Biomedical Research Institute of Barcelona - Higher Council for Scientific Research (IIBB-CSIC), Barcelona, Spain; Liver Unit, Hospital Clinic, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), the Center for Biomedical Research in Hepatic and Digestive Diseases (CIBEREHD), Barcelona, Spain; Southern California Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California.
| | - Anna Colell
- Department of Cell Death and Proliferation, Biomedical Research Institute of Barcelona - Higher Council for Scientific Research (IIBB-CSIC), Barcelona, Spain; Liver Unit, Hospital Clinic, Institute of Biomedical Research August Pi i Sunyer (IDIBAPS), the Center for Biomedical Research in Hepatic and Digestive Diseases (CIBEREHD), Barcelona, Spain.
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9
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Barbero-Camps E, Fernández A, Martínez L, Fernández-Checa JC, Colell A. APP/PS1 mice overexpressing SREBP-2 exhibit combined Aβ accumulation and tau pathology underlying Alzheimer's disease. Hum Mol Genet 2013; 22:3460-76. [PMID: 23648430 DOI: 10.1093/hmg/ddt201] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Current evidence indicates that excess brain cholesterol regulates amyloid-β (Aβ) deposition, which in turn can regulate cholesterol homeostasis. Moreover, Aβ neurotoxicity is potentiated, in part, by mitochondrial glutathione (mGSH) depletion. To better understand the relationship between alterations in cholesterol homeostasis and Alzheimer's disease (AD), we generated a triple transgenic mice featuring sterol regulatory element-binding protein-2 (SREBP-2) overexpression in combination with APPswe/PS1ΔE9 mutations (APP/PS1) to examine key biochemical and functional characteristics of AD. Unlike APP/PS1 mice, APP/PS1/SREBP-2 mice exhibited early mitochondrial cholesterol loading and mGSH depletion. Moreover, β-secretase activation and Aβ accumulation, correlating with oxidative damage and neuroinflammation, were accelerated in APP/PS1/SREBP-2 mice compared with APP/PS1 mice. Triple transgenic mice displayed increased synaptotoxicity reflected by loss of synaptophysin and neuronal death, resulting in early object-recognition memory impairment associated with deficits in spatial memory. Interestingly, tau pathology was present in APP/PS1/SREBP-2 mice, manifested by increased tau hyperphosphorylation and cleavage, activation of tau kinases and neurofibrillary tangle (NFT) formation without expression of mutated tau. Importantly, in vivo treatment with the cell permeable GSH ethyl ester, which restored mGSH levels in APP/PS1/SREBP-2 mice, partially prevented the activation of tau kinases, reduced abnormal tau aggregation and Aβ deposition, resulting in attenuated synaptic degeneration. Taken together, these results show that cholesterol-mediated mGSH depletion is a key event in AD progression, accelerating the onset of key neuropathological hallmarks of the disease. Thus, therapeutic approaches to recover mGSH may represent a relevant strategy in the treatment of AD.
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Angulo S, Morales A, Danese S, Llacuna L, Masamunt MC, Pultz N, Cifone MG, De Simone C, Delgado S, Vila J, Panés J, Donskey C, Fernández-Checa JC, Fiocchi C, Sans M. Probiotic sonicates selectively induce mucosal immune cells apoptosis through ceramide generation via neutral sphingomyelinase. PLoS One 2011; 6:e16953. [PMID: 21408067 PMCID: PMC3052310 DOI: 10.1371/journal.pone.0016953] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 01/18/2011] [Indexed: 01/02/2023] Open
Abstract
Background Probiotics appear to be beneficial in inflammatory bowel disease, but their mechanism of action is incompletely understood. We investigated whether probiotic-derived sphingomyelinase mediates this beneficial effect. Methodology/Principal Findings Neutral sphingomyelinase (NSMase) activity was measured in sonicates of the probiotic L. brevis (LB) and S. thermophilus (ST) and the non-probiotic E. coli (EC) and E. faecalis (EF). Lamina propria mononuclear cells (LPMC) were obtained from patients with Crohn's disease (CD) and Ulcerative Colitis (UC), and peripheral blood mononuclear cells (PBMC) from healthy volunteers, analysing LPMC and PBMC apoptosis susceptibility, reactive oxygen species (ROS) generation and JNK activation. In some experiments, sonicates were preincubated with GSH or GW4869, a specific NSMase inhibitor. NSMase activity of LB and ST was 10-fold that of EC and EF sonicates. LB and ST sonicates induced significantly more apoptosis of CD and UC than control LPMC, whereas EC and EF sonicates failed to induce apoptosis. Pre-stimulation with anti-CD3/CD28 induced a significant and time-dependent increase in LB-induced apoptosis of LPMC and PBMC. Exposure to LB sonicates resulted in JNK activation and ROS production by LPMC. NSMase activity of LB sonicates was completely abrogated by GW4869, causing a dose-dependent reduction of LB-induced apoptosis. LB and ST selectively induced immune cell apoptosis, an effect dependent on the degree of cell activation and mediated by bacterial NSMase. Conclusions These results suggest that induction of immune cell apoptosis is a mechanism of action of some probiotics, and that NSMase-mediated ceramide generation contributes to the therapeutic effects of probiotics.
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Affiliation(s)
- Sandra Angulo
- Department of Gastroenterology, Hospital Clinic, IDIBAPS, CIBER Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain
| | - Albert Morales
- Liver Unit, Hospital Clinic, IDIBAPS, CIBERehd, Barcelona, Spain
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona (IIBB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
| | - Silvio Danese
- Division of Gastroenterology, Istituto Clinico Humanitas, Milan, Italy
| | - Laura Llacuna
- Liver Unit, Hospital Clinic, IDIBAPS, CIBERehd, Barcelona, Spain
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona (IIBB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
| | - Maria Carme Masamunt
- Department of Gastroenterology, Hospital Clinic, IDIBAPS, CIBER Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain
| | - Nicole Pultz
- Infectious Diseases Section, Louis Stokes Cleveland Department of VA Medical Center, Cleveland, Ohio, United States of America
| | - Maria Grazia Cifone
- Department of Experimental Medicine, University of L'Aquila, L'Aquila, Italy
| | - Claudio De Simone
- Department of Experimental Medicine, University of L'Aquila, L'Aquila, Italy
| | - Salvadora Delgado
- Department of Gastrointestinal Surgery, Hospital Clinic, IDIBAPS, CIBERehd, Barcelona, Spain
| | - Jordi Vila
- Department of Clinical Microbiology, Hospital Clinic, IDIBAPS, CIBERehd, Barcelona, Spain
| | - Julián Panés
- Department of Gastroenterology, Hospital Clinic, IDIBAPS, CIBER Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain
| | - Curtis Donskey
- Infectious Diseases Section, Louis Stokes Cleveland Department of VA Medical Center, Cleveland, Ohio, United States of America
| | - Jose C. Fernández-Checa
- Liver Unit, Hospital Clinic, IDIBAPS, CIBERehd, Barcelona, Spain
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona (IIBB), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
- Research Center for Alcoholic Liver and Pancreatic Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
- * E-mail: (JCFC); (MS)
| | - Claudio Fiocchi
- Department of Gastroenterology and Hepatology, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
| | - Miquel Sans
- Department of Gastroenterology, Hospital Clinic, IDIBAPS, CIBER Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain
- * E-mail: (JCFC); (MS)
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11
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Fernández-Checa JC, Fernández A, Morales A, Marí M, García-Ruiz C, Colell A. Oxidative stress and altered mitochondrial function in neurodegenerative diseases: lessons from mouse models. CNS Neurol Disord Drug Targets 2010; 9:439-54. [PMID: 20522012 DOI: 10.2174/187152710791556113] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 02/01/2010] [Indexed: 11/22/2022]
Abstract
Oxidative stress has been consistently linked to ageing-related neurodegenerative diseases leading to the generation of lipid peroxides, carbonyl proteins and oxidative DNA damage in tissue samples from affected brains. Studies from mouse models that express disease-specific mutant proteins associated to the major neurodegenerative processes have underscored a critical role of mitochondria in the pathogenesis of these diseases. There is strong evidence that mitochondrial dysfunction is an early event in neurodegeneration. Mitochondria are the main cellular source of reactive oxygen species and key regulators of cell death. Moreover, mitochondria are highly dynamic organelles that divide, fuse and move along axons and dendrites to supply cellular energetic demands; therefore, impairment of any of these processes would directly impact on neuronal viability. Most of the disease-specific pathogenic mutant proteins have been shown to target mitochondria, promoting oxidative stress and the mitochondrial apoptotic pathway. In addition, disease-specific mutant proteins may also impair mitochondrial dynamics and recycling of damaged mitochondria via autophagy. Collectively, these data suggest that ROS-mediated defective mitochondria may accumulate during and contribute to disease progression. Strategies aimed to improve mitochondrial function or ROS scavenging may thus be of potential clinical relevance.
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Affiliation(s)
- J C Fernández-Checa
- Department of Cell Death and Proliferation, Instituto de Investigaciones Biomédicas de Barcelona, CSIC, Hospital Clínic i Provincial, IDIBAPS-CIBEK, and CIBEREHD, Spain.
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12
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Montero J, Mari M, Colell A, Morales A, Basañez G, Garcia-Ruiz C, Fernández-Checa JC. Cholesterol and peroxidized cardiolipin in mitochondrial membrane properties, permeabilization and cell death. Biochim Biophys Acta 2010; 1797:1217-24. [PMID: 20153716 PMCID: PMC2889134 DOI: 10.1016/j.bbabio.2010.02.010] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 02/04/2010] [Accepted: 02/08/2010] [Indexed: 02/06/2023]
Abstract
Mitochondria are known to actively regulate cell death with the final phenotype of demise being determined by the metabolic and energetic status of the cell. Mitochondrial membrane permeabilization (MMP) is a critical event in cell death, as it regulates the degree of mitochondrial dysfunction and the release of intermembrane proteins that function in the activation and assembly of caspases. In addition to the crucial role of proapoptotic members of the Bcl-2 family, the lipid composition of the mitochondrial membranes is increasingly recognized to modulate MMP and hence cell death. The unphysiological accumulation of cholesterol in mitochondrial membranes regulates their physical properties, facilitating or impairing MMP during Bax and death ligand-induced cell death depending on the level of mitochondrial GSH (mGSH), which in turn regulates the oxidation status of cardiolipin. Cholesterol-mediated mGSH depletion stimulates TNF-induced reactive oxygen species and subsequent cardiolipin peroxidation, which destabilizes the lipid bilayer and potentiates Bax-induced membrane permeabilization. These data suggest that the balance of mitochondrial cholesterol to peroxidized cardiolipin regulates mitochondrial membrane properties and permeabilization, emerging as a rheostat in cell death.
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Affiliation(s)
- Joan Montero
- Liver Unit and Centro de Investigaciones Biomédicas Esther Koplowitz, IMDiM, Hospital Clínic i Provincial and CIBEREHD, IDIBAPS, and Department of Cell Death and Proliferation, Instituto Investigaciones Biomédicas de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
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13
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Caballero F, Fernández A, De Lacy AM, Fernández-Checa JC, Caballería J, García-Ruiz C. Enhanced free cholesterol, SREBP-2 and StAR expression in human NASH. J Hepatol 2009; 50:789-96. [PMID: 19231010 DOI: 10.1016/j.jhep.2008.12.016] [Citation(s) in RCA: 249] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 11/06/2008] [Accepted: 11/10/2008] [Indexed: 12/17/2022]
Abstract
BACKGROUND/AIMS Non-alcoholic fatty liver disease (NAFLD) pathogenesis remains unknown. Due to the emerging role of free cholesterol (FC) in NAFLD, our aim was to examine the correlation between FC accumulation in patients with NAFLD and the expression of enzymes that regulate cholesterol homeostasis. METHODS Filipin staining, indicative of FC accumulation, and real-time PCR analyses were performed in 31 NAFLD patients and in seven controls. RESULTS All NASH patients (n=14) and 4 out of 17 patients with steatosis exhibited filipin staining compared to controls (0 out of 7 subjects with normal liver histology and BMI). Sterol regulatory element-binding protein-2 (SREBP-2) mRNA levels were 7- and 3-fold higher in NASH and steatosis patients, respectively, compared to controls. Since hydroxymethylglutaryl-CoA (HMG-CoA) reductase is the key enzyme in cholesterol synthesis and transcriptionally controlled by SREBP-2 we measured its mRNA levels, being 3- to 4-fold higher in NAFLD compared to controls, without any difference between NASH and steatosis patients. Fatty acid synthase (FAS) and SREBP-1c expression were not significantly induced in NAFLD, while ATP-binding cassette sub-family G member 1 (ABCG1), a transporter involved in cholesterol egress, and acyl-CoA-cholesterol acyltransferase mRNA levels were modestly increased (1.5- to 2.5-fold, p<0.05), regardless of fibrosis. Interestingly, mRNA levels of steroidogenic acute regulatory protein (StAR), a mitochondrial-cholesterol transporting polypeptide, increased 7- and 15-fold in steatosis and NASH patients, respectively, compared to controls. CONCLUSIONS FC increases in NASH and correlates with SREBP-2 induction. Moreover, StAR overexpression in NASH suggests that mitochondrial FC may be a player in disease progression and a novel target for intervention.
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Affiliation(s)
- Francisco Caballero
- Centro de Investigaciones Biomédicas Esther Koplowitz, IMDiM, Hospital Clínic i Provincial and CIBEREHD, IDIBAPS, Department of Cell Death and Proliferation, Instituto Investigaciones Biomédicas de Barcelona, Spain
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14
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Garcia-Ruiz C, Mari M, Colell A, Morales A, Caballero F, Montero J, Terrones O, Basañez G, Fernández-Checa JC. Mitochondrial cholesterol in health and disease. Histol Histopathol 2009; 24:117-32. [PMID: 19012251 DOI: 10.14670/hh-24.117] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cholesterol is a critical component of biological membranes, which not only plays an essential role in determining membrane physical properties, but also in the regulation of multiple signaling pathways. Cells satisfy their need for cholesterol either by uptake from nutrients and lipoproteins or de novo synthesis from acetyl-CoA. The latter process occurs in the endoplasmic reticulum, where transcription factors that regulate the expression of enzymes involved in the de novo cholesterol synthesis reside. Cholesterol is distributed to different membranes most prominently to plasma membrane, where it participates in the physical organization of specific membrane domains. Mitochondria, however, are considered cholesterol-poor organelles, and obtain their cholesterol load by the action of specialized proteins involved in its delivery from extramitochondrial sources and trafficking within mitochondrial membranes. Although mitochondrial cholesterol fulfills vital physiological functions, such as the synthesis of bile acids in the liver or the formation of steroid hormones in specialized tissues, recent evidence indicates that the accumulation of cholesterol in mitochondria may be a key step in disease progression, including steatohepatitis, carcinogenesis or Alzheimer disease.
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Affiliation(s)
- C Garcia-Ruiz
- Liver Unit and Centro de Investigaciones Biomédicas Esther Koplowitz, IMDiM, Hospital Clínic i Provincial and CIBEREHD, IDIBAPS, Barcelona, Spain
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15
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Colell A, Fernández A, García A, Fernández-Checa JC. P4‐184: Increased mitochondrial cholesterol enhances glial activation and neuronal oxidative stress induced by intracerebroventricular infusion of human beta‐amyloid. Alzheimers Dement 2008. [DOI: 10.1016/j.jalz.2008.05.2251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Anna Colell
- Instituto de Investigaciones Biomedicas de Barcelona (IIBB-CSIC). IDIBAPS. CIBEREHDBarcelonaSpain
| | - Anna Fernández
- Instituto de Investigaciones Biomedicas de Barcelona (IIBB-CSIC). IDIBAPS. CIBEREHDBarcelonaSpain
| | - Alberto García
- Instituto de Investigaciones Biomedicas de Barcelona (IIBB-CSIC). IDIBAPS. CIBEREHDBarcelonaSpain
| | - Jose C. Fernández-Checa
- Instituto de Investigaciones Biomedicas de Barcelona (IIBB-CSIC). IDIBAPS. CIBEREHDBarcelonaSpain
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Rabinovich RA, Bastos R, Ardite E, Llinàs L, Orozco-Levi M, Gea J, Vilaró J, Barberà JA, Rodríguez-Roisin R, Fernández-Checa JC, Roca J. Mitochondrial dysfunction in COPD patients with low body mass index. Eur Respir J 2007; 29:643-50. [PMID: 17182653 DOI: 10.1183/09031936.00086306] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Patients with chronic obstructive pulmonary disease (COPD) show abnormal adaptations of skeletal muscle redox status after exercise training. Increased skeletal muscle oxidative stress in COPD patients may prompt mitochondrial dysfunction. The present study explores the association between body composition and mitochondrial respiration in seven COPD patients with low body mass index (BMI(L)), eight COPD patients with normal body mass index (BMI(N)) and seven healthy controls. All of them underwent a vastus lateralis biopsy in which muscle structure, in vitro mitochondrial respiratory function, uncoupling protein 3 (UCP3) mRNA expression and glutathione levels in both isolated mitochondria and the whole muscle were determined. Mitochondrial respiratory function (assessed by acceptor control ratio (ACR)) was impaired in BMI(L) (2.2+/-0.6) compared with both BMI(N) (5.3+/-1.3) and controls (8.2+/-1.3). ACR significantly correlated with arterial oxygen tension and with muscle endurance but it showed a negative association with exercise-induced increase in blood lactate levels. UCP3 mRNA expression was reduced in BMI(L) patients. In conclusion, chronic obstructive pulmonary disease patients with low body mass index show electron transport chain dysfunction, which may contribute to low muscle endurance in the current subgroup of patients.
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Affiliation(s)
- R A Rabinovich
- Pneumology Service (ICT), Hospital Clinic, Barcelona University, Spain.
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Morales A, París R, Villanueva A, Llacuna L, García-Ruiz C, Fernández-Checa JC. Pharmacological inhibition or small interfering RNA targeting acid ceramidase sensitizes hepatoma cells to chemotherapy and reduces tumor growth in vivo. Oncogene 2006; 26:905-16. [PMID: 16862171 DOI: 10.1038/sj.onc.1209834] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Ceramidases (CDases) play a key role in cancer therapy through enhanced conversion of ceramide into sphingosine 1-phosphate (S1P), but their involvement in hepatocarcinogenesis is unknown. Here, we report that daunorubicin (DNR) activated acid CDase post-transcriptionally in established human (HepG2 cells) or mouse (Hepa1c1c7) hepatoma cell lines as well as in primary cells from murine liver tumors, but not in cultured mouse hepatocytes. Acid CDase silencing by small interfering RNA (siRNA) or pharmacological inhibition with N-oleoylethanolamine (NOE) enhanced the ceramide to S1P balance compared to DNR alone, sensitizing hepatoma cells (HepG2, Hep-3B, SK-Hep and Hepa1c1c7) to DNR-induced cell death. DNR plus NOE or acid CDase siRNA-induced cell death was preceded by ultrastructural changes in mitochondria, stimulation of reactive oxygen species generation, release of Smac/DIABLO and cytochrome c and caspase-3 activation. In addition, in vivo siRNA treatment targeting acid CDase reduced tumor growth in liver tumor xenografts of HepG2 cells and enhanced DNR therapy. Thus, acid CDase promotes hepatocarcinogenesis and its antagonism may be a promising strategy in the treatment of liver cancer.
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Affiliation(s)
- A Morales
- Liver Unit, Institut de Malalties Digestives, Hospital Clínic i Provincial, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
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18
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Ardite E, Barbera JA, Roca J, Fernández-Checa JC. Glutathione depletion impairs myogenic differentiation of murine skeletal muscle C2C12 cells through sustained NF-kappaB activation. Am J Pathol 2004; 165:719-28. [PMID: 15331397 PMCID: PMC1618592 DOI: 10.1016/s0002-9440(10)63335-4] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Skeletal muscle differentation is a complex process regulated at multiple levels. This study addressed the effect of glutathione (GSH) depletion on the transition of murine skeletal muscle C2C12 myoblasts into myocytes induced by growth factor inactivation. Cellular GSH levels increased within 24 hours on myogenic stimulation of myoblasts due to enhanced GSH synthetic rate accounted for by stimulated glutamate-L-cysteine ligase (also known as gamma-glutamylcysteine synthetase) activity. In contrast, the synthesis rate of GSH using gamma-glutamylcysteine and glutamate as precursors, which reflects the activity of the GSH synthetase, did not change during differentiation. The stimulation of GSH stores preceded the myogenic differentiation of C2C12 myoblasts monitored by expression of muscle-specific genes, creatine kinase (CK), myosin heavy chain (MyHC), and MyoD. The pattern of DNA binding activity of NF-kappaB and AP-1 in differentiating cells was similar both displaying an activation peak at 24 hours after myogenic stimulation. Depletion of cellular GSH levels 24 hours after stimulation of differentiation abrogated myogenesis as reflected by lower CK activity, MyHC levels, MyoD expression, and myotubes formation, effects that were reversible on GSH replenishment by GSH ethyl ester (GHSEE). Moreover, GSH depletion led to sustained activation of NF-kappaB, while GSHEE prevented it. Furthermore, inhibition of NF-kappaB activation restored myogenesis despite GSH depletion. Thus, GSH contributes to the formation of myotubes from satellite myoblasts by ensuring inactivation of NF-kappaB, and hence maintaining optimal GSH levels may be beneficial in restoring muscle mass in chronic inflammatory disorders.
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Affiliation(s)
- Esther Ardite
- Servei de Pneumologia, Instituto Clinic de Pneumologia y Cirugía Torácica, Barcelona, Spain
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19
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Coll O, Colell A, García-Ruiz C, Kaplowitz N, Fernández-Checa JC. Sensitivity of the 2-oxoglutarate carrier to alcohol intake contributes to mitochondrial glutathione depletion. Hepatology 2003; 38:692-702. [PMID: 12939596 DOI: 10.1053/jhep.2003.50351] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The mitochondrial pool of reduced glutathione (mGSH) is known to play a protective role against liver injury and cytokine-mediated cell death. However, the identification of the mitochondrial carriers involved in its transport in hepatocellular mitochondria remains unestablished. In this study, we show that the functional expression of the 2-oxoglutarate carrier from HepG2 cells in mitochondria from Xenopus laevis oocytes conferred a reduced glutathione (GSH) transport activity that was inhibited by phenylsuccinate, a specific inhibitor of the carrier. In addition, the mitochondrial transport of GSH and 2-oxoglutarate in isolated mitochondria from rat liver exhibited mutual competition and sensitivity to glutamate and phenylsuccinate. Interestingly, the kinetics of 2-oxoglutarate transport in rat liver mitochondria displayed a single Michaelis-Menten component with a Michaelis constant of 3.1 +/- 0.3 mmol/L and maximum velocity of 1.9 +/- 0.1 nmol/mg protein/25 seconds. Furthermore, the initial rate of 2-oxoglutarate was reduced in mitochondria from alcohol-fed rat livers, an effect that was not accompanied by an alcohol-induced decrease in the 2-oxoglutarate messenger RNA levels but rather by changes in mitochondrial membrane dynamics induced by alcohol. The fluidization of mitochondria by the fluidizing agent 2-(2-methoxyethoxy)ethyl 8-(cis-2-n-octylcyclopropyl) (A(2)C) restored the initial transport rate of both GSH and 2-oxoglutarate. Finally, these changes were reproduced in normal liver mitochondria enriched in cholesterol where the fluidization of cholesterol-enriched mitochondria with A(2)C restored the order membrane parameter and the mitochondrial 2-oxoglutarate uptake. In conclusion, these findings provide unequivocal evidence for 2-oxoglutarate as a GSH carrier and its sensitivity to membrane dynamics perturbation contributes in part to the alcohol-induced mGSH depletion.
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Affiliation(s)
- Olga Coll
- Liver Unit, Hospital Clínic i Provincial, Institut de Malalties Digestives, Instituto de Investigaciones Biomédicas August Pi i Sunyer, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
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20
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Ishii H, Adachi M, Fernández-Checa JC, Cederbaum AI, Deaciuc IV, Nanji AA. Role of apoptosis in alcoholic liver injury. Alcohol Clin Exp Res 2003; 27:1207-12. [PMID: 12878930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023]
Abstract
This article represents the proceedings of a symposium at the 2002 ISBRA/RSA meeting in San Francisco, USA. The organizer and chair was H. Ishii and co-chair was A.A. Nanji. The presentations were (1) INTRODUCTION: Apoptosis in alcoholic liver disease, by A. A. Nanji; (2) Mitochondria, oxidative stress and apoptosis in alcoholic liver disease, by M. Adachi; (3) Regulation of cell death by mitochondrial glutathione, by J.C. Fernández-Checa; (4) Toxicity of ethanol in HepG2 cells that express CYP2E1, by A.I. Cederbaum; (5) Is alcohol-enhanced liver apoptosis a pathogenic factor in alcoholic liver disease? by I.V. Deaciuc.
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Affiliation(s)
- Hiromasa Ishii
- Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
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21
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Quintero A, Pedraza CA, Siendones E, Kamal ElSaid AM, Colell A, García-Ruiz C, Montero JL, De la Mata M, Fernández-Checa JC, Miño G, Muntané J. PGE1 protection against apoptosis induced by D-galactosamine is not related to the modulation of intracellular free radical production in primary culture of rat hepatocytes. Free Radic Res 2002; 36:345-55. [PMID: 12071354 DOI: 10.1080/10715760290019372] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
D-galactosamine (D-GalN) toxicity is a useful experimental model of liver failure in human. It has been previously observed that PGE1 treatment reduced necrosis and apoptosis induced by D-GalN in rats. Primary cultured rat hepatocytes were used to evaluate if intracellular oxidative stress was involved during the induction of apoptosis and necrosis by D-GalN (0-40mM). Also, the present study investigated if PGE1 (1 microM) was equally potent reducing both types of cell death. The presence of hypodiploid cells, DNA fragmentation and caspase-3 activation were used as a marker of hepatocyte apoptosis. Necrosis was measured by lactate dehydrogenase (LDH) release. Oxidative stress was evaluated by the intracellular production of hydrogen peroxide (H2O2), the disturbances on the mitochondrial transmembrane potential (MTP), thiobarbituric-reacting substances (TBARS) release and the GSH/GSSG ratio. Data showed that intermediate range of D-GalN concentrations (2.5-10mM) induced apoptosis in association with a moderate oxidative stress. High D-GalN concentration (40 mM) induced a reduction of all parameters associated with apoptosis and enhanced all those related to necrosis and intracellular oxidative stress, including a reduction of GSH/GSSG ratio and MTP in comparison with D-GalN (2.5-10 mM)-treated cells. Although PGE1 reduced apoptosis induced by D-GalN, it was not able to reduce the oxidative stress and cell necrosis induced by the hepatotoxin in spite to its ability to abolish the GSH depletion.
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Affiliation(s)
- A Quintero
- Unidad de Investigación, Servicio Aparato Digestivo, Hospital Universitario Reína Sofía, Córdoba, Spain
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22
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Colell A, Coll O, García-Ruiz C, París R, Tiribelli C, Kaplowitz N, Fernández-Checa JC. Tauroursodeoxycholic acid protects hepatocytes from ethanol-fed rats against tumor necrosis factor-induced cell death by replenishing mitochondrial glutathione. Hepatology 2001; 34:964-71. [PMID: 11679967 DOI: 10.1053/jhep.2001.28510] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Mitochondrial glutathione (GSH) plays a key role against tumor necrosis factor alpha (TNF)-induced apoptosis because its depletion is known to sensitize hepatocytes to TNF. The present study examined the role of tauroursodeoxycholic acid (TUDCA) administration to chronic ethanol-fed rats on mitochondrial GSH levels and kinetics, mitochondrial membrane physical properties, TNF-induced peroxide formation, and subsequent hepatocyte survival. TUDCA selectively increased the levels of GSH in mitochondria without an effect on cytosolic GSH. This outcome was accompanied by improved initial rate of GSH transport examined at low (1 mmol/L) and high (10 mmol/L) GSH concentrations both in intact mitochondria and mitoplasts prepared from ethanol-fed livers. Assessment of membrane fluidity revealed an increased order parameter in mitochondria and mitoplasts from ethanol-fed rats compared with pair-fed controls, which was prevented by TUDCA administration. Compared with hepatocytes from pair-fed rats, TNF stimulated peroxide generation in hepatocytes from ethanol-fed rats, preceding TNF-induced cell death. Administration of TUDCA to ethanol-fed rats prevented TNF-induced peroxide formation and cell death, an effect that was reversed on depletion of the recovered mitochondrial GSH levels by (R,S)-3-hydroxy-4-pentenoate before TNF treatment. The protective effect of TUDCA against TNF was not because of activation of phosphatidylinositol 3-kinase, discarding a role for a survival-dependent pathway. Thus, these findings reveal a novel role of TUDCA in protecting hepatocytes in long-term ethanol-fed rats through modulation of mitochondrial membrane fluidity and subsequent normalization of mitochondrial GSH levels.
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Affiliation(s)
- A Colell
- Liver Unit, Instituto de Malalties Digestives, Hospital Clinic i Provincial, Barcelona, Spain
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23
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Gudayol M, Vidal J, Usac EF, Morales A, Fabregat ME, Fernández-Checa JC, Novials A, Gomis R. Identification and functional analysis of mutations in FAD-binding domain of mitochondrial glycerophosphate dehydrogenase in caucasian patients with type 2 diabetes mellitus. Endocrine 2001; 16:39-42. [PMID: 11822825 DOI: 10.1385/endo:16:1:39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2001] [Revised: 10/01/2001] [Accepted: 10/02/2001] [Indexed: 11/11/2022]
Abstract
Ca2+-responsive mitochondrial FAD-linked glycerophosphate dehydrogenase (mGPDH) is a key component of the pancreatic beta-cell glucose-sensing device. The purpose of this study was to examine the association of mutations in the cDNA coding for the FAD-binding domain of mGPDH and to explore the functional consequences of these mutations in vitro. To investigate this association in type 2 diabetes mellitus, we studied a cohort of 168 patients with type 2 diabetes and 179 glucose-tolerant control subjects of Spanish Caucasian origin by single-stranded conformational polymorphism analysis. In vitro site-directed mutagenesis was performed in the mGPDH cDNA sequence to reproduce those mutations that produce amino acid changes in a patient with type 2 diabetes. We detected mutations in the mGPDH FAD-binding domain in a single patient, resulting in a Gly to Arg amino acid change at positions 77, 78, and 81 and a Thr to Pro at position 90. In vitro expression of the mutated constructs in Xenopus oocytes resulted in a significantly lower enzymatic activity than in cells expressing the wild-type form of the enzyme. Our results indicate that although mutations in the mGPDH gene do not appear to have a major role in type 2 diabetes mellitus, the reduction in mGPDH enzymatic activity associated with the newly described mGPDH mutations suggests that they may contribute to the disease in some patients.
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Affiliation(s)
- M Gudayol
- Endocrinology and Diabetes Unit, Hospital Clinic de Barcelona, Spain
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Colell A, García-Ruiz C, Roman J, Ballesta A, Fernández-Checa JC. Ganglioside GD3 enhances apoptosis by suppressing the nuclear factor-kappa B-dependent survival pathway. FASEB J 2001; 15:1068-70. [PMID: 11292670 DOI: 10.1096/fj.00-0574fje] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- A Colell
- Liver Unit, Instituto de Malalties Digestives, Hospital Clinic i Provincial, Barcelona, 08036, Spain
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25
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García-Ruiz C, Marí M, Morales A, Colell A, Ardite E, Fernández-Checa JC. Human placenta sphingomyelinase, an exogenous acidic pH-optimum sphingomyelinase, induces oxidative stress, glutathione depletion, and apoptosis in rat hepatocytes. Hepatology 2000; 32:56-65. [PMID: 10869289 DOI: 10.1053/jhep.2000.8267] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Ceramide has been identified as a putative lipid messenger that mediates diverse cellular processes including cell death. Since glutathione (GSH) depletion is known to sensitize cells to many cytotoxic agents and as a result of the reported regulation of neutral sphyngomyelinase (NSMase) by GSH, the present study compared the role of individual SMases in the induction of oxidative stress, regulation of cellular GSH, and apoptosis of rat hepatocytes. Exposure of cultured rat hepatocytes to exogenous Bacillus cereus sphingomyelinase (bSMase), a neutral SMase, or human placenta sphingomyelinase (hSMase), an acidic SMase (ASMase), generated similar ceramide levels in a dose-dependent manner. However, whereas bSMase increased hepatocellular GSH levels, hSMase depleted GSH stores, an effect that was prevented by monensin and mannose 6-phosphate (M-6-P), suggesting that exogenous hSMase enters hepatocytes by endocytosis and is delivered to an endosomal/lysosomal acidic compartment. Interestingly, despite the differential effect of either SMases on cell GSH levels, both bSMase and hSMase increased gamma-glutamylcysteine synthetase heavy-subunit chain (gamma-GCS-HS) mRNA levels. Consistent with these findings on GSH regulation, hSMase, but not bSMase, generated reactive oxygen species (ROS), being accompanied by mitochondrial depolarization, suggesting that hSMase targeted mitochondria, leading to oxidative stress. Accordingly, hepatocytes displayed a selective sensitivity to hSMase in contrast to bSMase exposure, and depletion of GSH stores enhanced susceptibility to hSMase as a result of potentiation of ROS formation and caspase 3 activation. Thus, these findings reveal the ability of ASMase to induce oxidative stress as a result of the targeting of mitochondria, and that GSH depletion sensitizes hepatocytes to the ASMase-induced apoptosis.
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Affiliation(s)
- C García-Ruiz
- Liver Unit, Instituto Malalties Digestives, Hospital Clinic i Provencial, Instituto de Investigaciones Biom¿edicas, August Pi i Sunyer, Consejo Superior Investigaciones Cient¿ificas, Barcelona 08036, Barcelona, Spain
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26
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Román J, Giménez A, Lluis JM, Gassó M, Rubio M, Caballeria J, Parés A, Rodés J, Fernández-Checa JC. Enhanced DNA binding and activation of transcription factors NF-kappa B and AP-1 by acetaldehyde in HEPG2 cells. J Biol Chem 2000; 275:14684-90. [PMID: 10799556 DOI: 10.1074/jbc.275.19.14684] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Because transcription factors NF-kappaB and activator protein-1 (AP-1) are known to regulate gene expression, we have analyzed the role of acetaldehyde in the activation of NF-kappaB and AP-1 in HepG2 cells. Binding activity and transactivation of NF-kappaB and AP-1 were determined by gel retardation assays and transfection of a luciferase reporter construct controlled by kappaB and AP-1 binding sites, respectively. Acetaldehyde enhanced the DNA binding of NF-kappaB and AP-1 by 1 and 4 h, respectively, increasing the kappaB- and AP-1-dependent luciferase expression. Supershift assays revealed the presence of NF-kappaB heterodimers p65/p50 and p50/p52, whereas nuclear c-Jun levels correlated with the DNA binding of AP-1. The enhanced binding of NF-kappaB to DNA by acetaldehyde in intact cells was accompanied by the proteolytic degradation of IkappaB-alpha. However, the addition of acetaldehyde to cytostolic extracts from untreated Hep G2 cells did not affect the DNA binding of AP-1 but activated the NF-kappaB heterodimer p65/p50 in the absence of IkappaB-alpha degradation. Preincubation of HepG2 cells with protein kinase C inhibitors abolished the enhanced DNA binding of NF-kappaB and AP-1 caused by acetaldehyde. Hence, these findings uncover a previously unrecognized role for acetaldehyde in the activation of NF-kappaB and AP-1, which may be of relevance in the alcohol-induced liver disease.
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Affiliation(s)
- J Román
- Liver Unit, Institut Malalties Digestives and Instituto de Investigaciones Biomedicas August Pi Suñer, Consejo Superior de Investigaciones Cientificas, Barcelona 08036, Spain
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García-Ruiz C, Colell A, París R, Fernández-Checa JC. Direct interaction of GD3 ganglioside with mitochondria generates reactive oxygen species followed by mitochondrial permeability transition, cytochrome c release, and caspase activation. FASEB J 2000; 14:847-58. [PMID: 10783138 DOI: 10.1096/fasebj.14.7.847] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Glycosphingolipids, including gangliosides, are emerging as signaling intermediates of extracellular stimuli. Because mitochondria play a key role in the orchestration of death signals, we assessed the interaction of GD3 ganglioside (GD3) with mitochondria and the subsequent cascade of events that culminate in cell death. In vitro studies with isolated mitochondria from rat liver demonstrate that GD3 elicited a burst of peroxide production within 15-30 min, which preceded the opening of the mitochondrial permeability transition, followed by cytochrome c (cyt c) release. These effects were mimicked by lactosylceramide and N-acetyl-sphingosine but not by sphinganine or sphingosine and were prevented by cyclosporin A and butylated hydroxytoluene (BHT). Reconstitution of mitochondria pre-exposed to GD3 with cytosol from rat liver in a cell-free system resulted in the proteolytic processing of procaspase 3 and subsequent caspase 3 activation. Intact hepatocytes or U937 cells selectively depleted of glutathione in mitochondria by 3-hydroxyl-4-pentenoate (HP) with the sparing of cytosol reduced glutathione (GSH) were sensitized to GD3, manifested as an apoptotic death. Inhibition of caspase 3 prevented the apoptotic phenotype of HP-treated cells caused by GD3 without affecting cell survival; in contrast, BHT fully protected HP-treated cells to GD3 treatment. Treatment of cells with tumor necrosis factor increased the level of GD3, whereas blockers of mitochondrial respiration at complex I and II protected sensitized cells to GD3 treatment. Thus, the effect of GD3 as a lipid death effector is determined by its interaction with mitochondria leading to oxidant-dependent caspase activation. Mitochondrial glutathione plays a key role in controlling cell survival through modulation of the oxidative stress induced by glycosphingolipids.
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Affiliation(s)
- C García-Ruiz
- Liver Unit, Department of Medicine, Hospital Clinic i Provincial and Instituto de Investigaciones Biomedicas August Pi Suñer, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
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Ardite E, Sans M, Panés J, Romero FJ, Piqué JM, Fernández-Checa JC. Replenishment of glutathione levels improves mucosal function in experimental acute colitis. J Transl Med 2000; 80:735-44. [PMID: 10830784 DOI: 10.1038/labinvest.3780077] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Because reactive oxygen species (ROS) have been implicated as mediators of inflammatory bowel disease (IBD), the purpose of the present work was to determine the functional role of mucosal GSH in the trinitrobenzenesulfonic acid in 50% ethanol (TNBS+ethanol)-induced colitis in rats. Mucosal samples were taken to evaluate the temporal relationship between the extent of injury, the levels of glutathione (GSH) during acute colitis induced by TNBS+ethanol, and the effect of N-acetylcysteine (NAC) administration. In vitro assays revealed the interaction of TNBS with GSH leading to the almost instantaneous disappearance of GSH, while the reductive metabolism of TNBS by GSSG reductase generated ROS. Mucosal samples from TNBS+ethanol-treated rats indicated a direct correlation between GSH depletion and injury detected as soon as 30 minutes after TNBS+ethanol administration that persisted 24 hours post treatment. Although, short term depletion of mucosal GSH per se by diethylmaleate did not result in mucosal injury, the oral administration of NAC (40 mM) 4 hours after TNBS+ethanol treatment increased GSH stores (2-fold), decreasing the extent of mucosal injury (60-70%) examined at 24 hours post treatment. However, an equimolar dose of dithiothreitol failed to increase GSH levels and protect mucosa from TNBS+ethanol-induced injury. Interestingly, GSH levels in TNBS+ethanol-treated rats recovered by 1-2 weeks, an effect that was accounted for by an increase of gamma-glutamylcysteine synthetase (gamma-GCS) activity due to an induction of gamma-GCS-heavy subunit chain mRNA. Thus, TNBS promotes two independent mechanisms of injury, GSH depletion and ROS generation, both being required for the manifestation of mucosal injury as GSH limitation renders intestine susceptible to the TNBS-induced ROS overgeneration. Accordingly, in vivo administration of NAC attenuates the acute colitis through increased mucosal GSH levels, suggesting that GSH precursors may be of relevance in the acute relapse of IBD.
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Affiliation(s)
- E Ardite
- Liver Unit, Institut Malalties Digestives, Instituto Investigaciones Biomedicas August Pi I Suñer, Consejo Superior Investigaciones Cientificas, Barcelona, Spain
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29
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Román J, Colell A, Blasco C, Caballeria J, Parés A, Rodés J, Fernández-Checa JC. Differential role of ethanol and acetaldehyde in the induction of oxidative stress in HEP G2 cells: effect on transcription factors AP-1 and NF-kappaB. Hepatology 1999; 30:1473-80. [PMID: 10573527 DOI: 10.1002/hep.510300623] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The oxidative metabolism of ethanol by the cytochrome P450 2E1 (CYP2E1) has been recognized to contribute to the ethanol-induced deleterious effects through the induction of oxidative stress. This study compared the effect of ethanol and acetaldehyde in the induction of oxidative stress and activation of transcription factors nuclear factor-kappaB (NF-kappaB) and activating protein 1 (AP-1) in HepG2 cells, which do not express CYP2E1, and HepG2 cells transfected with CYP2E1 (E47 cells). Neither ethanol (80 mmol/L) nor acetaldehyde (25-200 micromol/L) caused oxidative stress in HepG2 cells, an effect that was independent of blocking reduced glutathione (GSH) synthesis with buthionine-L-sulfoximine (BSO). However, BSO preincubation caused an overproduction of peroxides and activation of NF-kappaB and AP-1 in E47 cells even in the absence of ethanol. Furthermore, the incubation of E47 cells with ethanol (80 mmol/L for up to 5 days) depleted cellular GSH stores in both cytosol and mitochondria, reflecting the induction of oxidative stress. Ethanol activated NF-kappaB and AP-1 in E47 cells, an effect that was prevented by 4-methylpyrazole, potentiated by cyanamide, and attenuated by trolox C. Interestingly, however, despite the inability of acetaldehyde to induce oxidative stress in HepG2, acetaldehyde activated NF-kappaB and AP-1; in contrast, ethanol failed to activate these transcription factors in HepG2. Thus, our findings indicate that activation of NF-kappaB and AP-1 by ethanol and acetaldehyde occurs through distinct mechanisms. CYP2E1 is indispensable in the induction of oxidative stress from ethanol, whereas the activation of NF-kappaB and AP-1 by acetaldehyde is independent of oxidative stress.
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Affiliation(s)
- J Román
- Liver Unit, Department of Medicine, and Instituto de Investigaciones Biomedicas August Pi Suñer, Consejo Superior de Investigaciones Científicas, Barcelona, Spain
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30
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Abstract
BACKGROUND/AIMS The mechanisms underlying the initial graft dysfunction in liver transplantation are not completely understood, although much of the liver graft injury derives from the ischemia/reperfusion-induced oxidative stress. Thus, the purpose of our study was to determine the involvement of oxidative stress in the initial graft dysfunction in human liver transplantation. METHODS Liver biopsies were taken at different times of the transplantation procedure, at the organ donor laparatomy (T1), before graft reperfusion (T2), and 5-60 min after graft reperfusion (T3), determining the levels of GSH, GSSG, as well as peroxides and malondialdehyde in liver homogenates. RESULTS Patients were graded into two groups depending on whether the peak serum alanine aminotransferases within the first 3 postoperative days were lower (group A, mild to moderate injury: 32 patients) or higher (group B, severe injury: 5 patients) than 2500 U/l. The levels of GSH at time intervals T1-T3 were similar for groups A and B, with a trend to lower GSSG levels in group B at T2 and T3 samples. This outcome was accompanied by unchanged levels of malondialdehyde and hydrogen peroxide in the same samples in both groups of patients. No patient developed primary graft nonfunction. One-year cumulative survival was 81% and 60% in groups A and B, respectively (p>0.05). CONCLUSIONS These findings indicate a lack of significant generation of reactive oxygen species and consequent oxidative stress as a major factor involved in the pathogenesis of the initial graft dysfunction in human liver transplantation.
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Affiliation(s)
- E Ardite
- Department of Medicine, Hospital Clinic, Universidad de Barcelona, Instituto de Investigaciones Biomédicas, Consejo Superior de Investigaciones Cientificas, Spain
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31
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Sans M, Panés J, Ardite E, Elizalde JI, Arce Y, Elena M, Palacín A, Fernández-Checa JC, Anderson DC, Lobb R, Piqué JM. VCAM-1 and ICAM-1 mediate leukocyte-endothelial cell adhesion in rat experimental colitis. Gastroenterology 1999; 116:874-83. [PMID: 10092309 DOI: 10.1016/s0016-5085(99)70070-3] [Citation(s) in RCA: 157] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS The molecular mechanisms responsible for leukocyte recruitment in experimental colitis are poorly understood. The aims of this study were to measure expression of endothelial intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) and to determine their role in leukocyte recruitment in experimental colitis. METHODS Rats with trinitrobenzene sulfonic acid (TNBS)-induced colitis and control rats were studied 1, 7, or 21 days after treatment. ICAM-1 and VCAM-1 expressions were measured by the double radiolabeled antibody technique. Leukocyte-endothelial cell interactions were determined in colonic venules by fluorescence intravital microscopy. Therapeutic effects of treatment with anti-VCAM-1 antibodies were also assessed. RESULTS Colonic endothelial ICAM-1 was constitutively expressed and did not increase in colitic animals. In contrast, constitutive expression of VCAM-1 was low but markedly increased (6-fold) 1 and 7 days after induction of colitis. Increased colonic expression of VCAM-1 paralleled macroscopic damage score, myeloperoxidase activity, and increased leukocyte adhesion in colonic venules. The latter was significantly decreased by immunoneutralization of ICAM-1 and completely abrogated by immunoneutralization of VCAM-1. Long-term administration of anti-VCAM-1 antibody resulted in significant attenuation of colitis. CONCLUSIONS Induction of colitis in rats by TNBS is followed by up-regulation of endothelial VCAM-1. VCAM-1 and constitutive ICAM-1 are major determinants of leukocyte recruitment to the inflamed intestine.
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Affiliation(s)
- M Sans
- Department of Gastroenterology, Institut d'Investigacions Biomédiques August Pi i Sunyer, Hospital Clínic, Barcelona, Spain
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Abstract
Accumulating evidence pointing to mitochondria as critical participants in the control of apoptotic and necrotic cell death and in the development of specific disease states has led to a renaissance on the study of these organelles. Because mitochondria are the major consumers of molecular oxygen within cells, they stand as one of the most important generators of reactive oxygen species and therefore constitute potential targets of therapeutic intervention in pathologic states in which oxidative stress originates from these organelles. In this regard, mitochondria are specific targets of ethanol intoxication, thereby leading to reported morphologic and functional alterations of mitochondria. Because mitochondria are also indispensable for the maintenance of cell functions, their dysfunction induced by ethanol may be a key event in the development of alcoholic liver disease. Indeed, chronic ethanol feeding in experimental animals has been reported to cause a selective deficiency in the availability of reduced glutathione (GSH) in mitochondria due to the impaired functioning of the specific mitochondrial carrier that translocates GSH from cytosol into the mitochondrial matrix. Such a selective depletion sensitizes hepatocytes from chronic ethanol-fed animals to the oxidative effects of cytokines, e.g., tumor necrosis factor (TNF). Restoration of mitochondrial GSH by the in vivo administration of S-adenosyl-L-methionine or the in vitro use of GSH ethyl ester prevents the susceptibility of hepatocytes to TNF. Although the nature of this specific carrier has not yet been uncovered, the elucidation of the mechanisms whereby ethanol leads to its impaired activity may provide important clues as to its function and mechanism of action, which in turn may be useful toward the definitive characterization and identification of this important carrier.
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Affiliation(s)
- J C Fernández-Checa
- Department of Medicine, Hospital Clinic i Provincial and Instituto Investigaciones Biomédicas August Pi i Sunyer, Consejo Superior Investigaciones Científicas, Barcelona, Spain
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Colell A, García-Ruiz C, Miranda M, Ardite E, Marí M, Morales A, Corrales F, Kaplowitz N, Fernández-Checa JC. Selective glutathione depletion of mitochondria by ethanol sensitizes hepatocytes to tumor necrosis factor. Gastroenterology 1998; 115:1541-51. [PMID: 9834283 DOI: 10.1016/s0016-5085(98)70034-4] [Citation(s) in RCA: 291] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND & AIMS Tumor necrosis factor (TNF)-alpha induces cell injury by generating oxidative stress from mitochondria. The purpose of this study was to determine the effect of ethanol on the sensitization of hepatocytes to TNF-alpha. METHODS Cultured hepatocytes from ethanol-fed (ethanol hepatocytes) or pair-fed (control hepatocytes) rats were exposed to TNF-alpha, and the extent of oxidative stress, gene expression, and viability were evaluated. RESULTS Ethanol hepatocytes, which develop a selective deficiency of mitochondrial glutathione (mGSH), showed marked susceptibility to TNF-alpha. The susceptibility to TNF-alpha, manifested as necrosis rather than apoptosis, was accompanied by a progressive increase in hydrogen peroxide that correlated inversely with cell survival. Nuclear factor kappaB activation by TNF-alpha was significantly greater in ethanol hepatocytes than in control hepatocytes, an effect paralleled by the expression of cytokine-induced neutrophil chemoattractant. Similar sensitization of normal hepatocytes to TNF-alpha was obtained by depleting the mitochondrial pool of GSH with 3-hydroxyl-4-pentenoate. Restoration of mGSH by S-adenosyl-L-methionine or by GSH-ethyl ester prevented the increased susceptibility of ethanol hepatocytes to TNF-alpha. CONCLUSIONS These results indicate that mGSH controls the fate of hepatocytes in response to TNF-alpha. Its depletion caused by alcohol consumption amplifies the power of TNF-alpha to generate reactive oxygen species, compromising mitochondrial and cellular functions that culminate in cell death.
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Affiliation(s)
- A Colell
- Liver Unit, Department of Medicine, Hospital Clinic i Provincial and Instituto Investigaciones Biomédicas, Consejo Superior Investigaciones Cientificas, Barcelona, Spain
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Morales A, Miranda M, Sánchez-Reyes A, Biete A, Fernández-Checa JC. Oxidative damage of mitochondrial and nuclear DNA induced by ionizing radiation in human hepatoblastoma cells. Int J Radiat Oncol Biol Phys 1998; 42:191-203. [PMID: 9747838 DOI: 10.1016/s0360-3016(98)00185-0] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE Since reactive oxygen species (ROS) act as mediators of radiation-induced cellular damage, the aim of our studies was to determine the effects of ionizing radiation on the regulation of hepatocellular reduced glutathione (GSH), survival and integrity of nuclear and mitochondrial DNA (mtDNA) in human hepatoblastoma cells (Hep G2) depleted of GSH prior to radiation. METHODS AND MATERIALS GSH, oxidized glutathione (GSSG), and generation of ROS were determined in irradiated (50-500 cGy) Hep G2 cells. Clonogenic survival, nuclear DNA fragmentation, and integrity of mtDNA were assessed in cells depleted of GSH prior to radiation. RESULTS Radiation of Hep G2 cells (50-400 cGy) resulted in a dose-dependent generation of ROS, an effect accompanied by a decrease of reduced GSH, ranging from a 15% decrease for 50 cGy to a 25% decrease for 400 cGy and decreased GSH/GSSG from a ratio of 17 to a ratio of 7 for controls and from 16 to 6 for diethyl maleate (DEM)-treated cells. Depletion of GSH prior to radiation accentuated the increase of ROS by 40-50%. The depletion of GSH by radiation was apparent in different subcellular sites, being particularly significant in mitochondria. Furthermore, depletion of nuclear GSH to 50-60% of initial values prior to irradiation (400 cGy) resulted in DNA fragmentation and apoptosis. Consequently, the survival of Hep G2 to radiation was reduced from 25% of cells not depleted of GSH to 10% of GSH-depleted cells. Fitting the survival rate of cells as a function of GSH using a theoretical model confirmed cellular GSH as a key factor in determining intrinsic sensitivity of Hep G2 cells to radiation. mtDNA displayed an increased susceptibility to the radiation-induced loss of integrity compared to nuclear DNA, an effect that was potentiated by GSH depletion in mitochondria (10-15% intact mtDNA in GSH-depleted cells vs. 25-30% of repleted cells). CONCLUSION GSH plays a critical protective role in maintaining nuclear and mtDNA functional integrity, determining the intrinsic radiosensitivity of Hep G2. Although the DNA repair is a complex process that is not yet completely understood, the protective role of GSH probably does not seem to involve the repair of classical DNA damage but may relate to modification of DNA damage dependent signaling.
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Affiliation(s)
- A Morales
- Instituto Investigaciones Biomédicas, August Pi i Suñer (IDIBAPS), CSIC-UB, Barcelona, Spain
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Bosch-Morell F, Martínez-Soriano F, Colell A, Fernández-Checa JC, Romero FJ. Chronic ethanol feeding induces cellular antioxidants decrease and oxidative stress in rat peripheral nerves. Effect of S-adenosyl-L-methionine and N-acetyl-L-cysteine. Free Radic Biol Med 1998; 25:365-8. [PMID: 9680183 DOI: 10.1016/s0891-5849(98)00036-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Chronic ethanol feeding promotes oxidative stress in rat peripheral nerve. Malondialdehyde, a lipid peroxidation product, content increases in sciatic nerves of rats fed an ethanol-containing diet, when compared with pair-fed animals. Moreover, glutathione content and glutathione peroxidase activity in this same tissue decrease in ethanol-fed vs. pair-fed rats. S-Adenosyl-L-methionine and N-acetyl-L-cysteine, both with possible therapeutic action on alcoholism, were tested in this animal model. Only N-acetyl-L-cysteine was able to normalize malondialdehyde content and to restore glutathione content and glutathione peroxidase activity, to values not significantly different from those of sciatic nerves from pair-fed animals. The reasons for the different effect of both substances tested is also discussed.
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Affiliation(s)
- F Bosch-Morell
- Department of Physiology, School of Medicine and Dentistry, University of Valencia, Spain
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Ardite E, Panés J, Miranda M, Salas A, Elizalde JI, Sans M, Arce Y, Bordas JM, Fernández-Checa JC, Piqué JM. Effects of steroid treatment on activation of nuclear factor kappaB in patients with inflammatory bowel disease. Br J Pharmacol 1998; 124:431-3. [PMID: 9647464 PMCID: PMC1565427 DOI: 10.1038/sj.bjp.0701887] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Nuclear factor kappB (NFkappaB) is a transcription factor that controls several genes important for immunity and inflammation. The aim of this study was to assess if activation of NFkappaB plays a role in the pathogenesis of inflammatory bowel disease (IBD), and whether steroid treatment affects NFkappaB activation. Activation of NFkappaB was analysed in colon biopsy samples of 13 patients with active IBD (8 Crohn's colitis, 5 ulcerative colitis) by electrophoretic mobility-shift assays, under basal conditions and 3 weeks after treatment with 0.75 mg kg(-1) day(-1) prednisolone. The presence of interleukin-8 mRNA in biopsies was assessed by RT-PCR. A specific NFkappaB band was present in all nuclear extracts from inflamed mucosa, whereas the band was barely detectable in uninflamed colonic mucosa. NFkappaB bands were super-shifted by antibodies against p50 subunit, whereas antibodies against p65, p52, c-Rel, or Rel B did not modify the mobility of the band. Increased interleukin-8 mRNA was detected at the same sites of NFkappaB activation. Steroid-induced healing of colonic inflammation was associated with disappearance of NFkappaB from nuclear extracts. These results support the notion that NFkappaB plays an important role in the pathogenesis of IBD, and that blockade of NFkappaB activation is one of the mechanisms by which steroids suppress the inflammatory cascade in IBD.
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Affiliation(s)
- E Ardite
- Consejo Superior Investigaciones Científicas, Barcelona, Spain
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Morales A, Miranda M, Sanchez-Reyes A, Colell A, Biete A, Fernández-Checa JC. Transcriptional regulation of the heavy subunit chain of gamma-glutamylcysteine synthetase by ionizing radiation. FEBS Lett 1998; 427:15-20. [PMID: 9613591 DOI: 10.1016/s0014-5793(98)00381-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Since glutathione (GSH) protects against oxidative stress, we determined the regulation of cellular GSH by ionizing radiation in human hepatoblastoma cells, HepG2. The levels of GSH increased in irradiated HepG2 due to a greater gamma-glutamylcysteine synthetase (gamma-GCS) activity, which was paralleled by gamma-GCS heavy subunit chain (gamma-GCS-HS) mRNA levels. Transcription of deletion constructs of the gamma-GCS-HS promoter cloned in a reporter vector was associated with activator protein-1 (AP-1), consistent with the DNA binding of AP-1 in nuclear extracts of irradiated HepG2. Hence, the transcriptional regulation of gamma-GCS by ionizing radiation emerges as an adaptive mechanism, which may be of significance to control the consequences of the oxidative stress induced by radiation.
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Affiliation(s)
- A Morales
- Instituto de Investigaciones Biomédicas, August Pi i Sunyer, CSIC-UB, Hospital Clinic i Provincial, Barcelona, Spain
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38
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Abstract
Increasing evidence has unraveled a dual functional role of mitochondria as suppliers of the energy required for cell viability, and critical players in the pathway leading to cell death. Consequence of their physiological role in the oxidative phosphorylation is the generation of reactive oxygen species (ROS) as byproducts of the consumption of molecular oxygen in the electron transport chain. Superoxide anion and hydrogen peroxide produced during aerobic respiration are precursors of hydroxyl radical by the participation of transition metals. Glutathione (GSH) in mitochondria is the only defense available to metabolize hydrogen peroxide. A small fraction of the total cellular pool of GSH is sequestered in mitochondria by the action of a carrier that transports GSH from cytosol to the mitochondrial matrix. Recent evidence position mitochondria as subcellular targets of cytokines leading to overproduction of ROS induced by ceramide, a lipid intermediate of cytokine action. Chronic ethanol-fed cells are selectively depleted of GSH in mitochondria due to a defective operation of the carrier responsible for the transport of GSH from cytosol into the mitochondrial matrix. Its limitation sensitizes alcohol hepatocytes to the prooxidant effects of cytokines and prooxidants generated by the oxidative metabolism of ethanol. One of the mechanisms leading to the onset of selective defect in the mitochondrial transport of GSH induced by chronic ethanol exposure is mediated by decreased fluidity of the mitochondrial inner membrane. Its fluidization by SAM treatment normalizes the steady state levels of GSH in mitochondria contributing to withstand the oxidative stress derived by the oxidative metabolism of ethanol.
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Affiliation(s)
- J C Fernández-Checa
- Instituto Investigaciones Biomédicas, Consejo Superior Investigaciones Científicas (CSIC), Hospital Clinic i Provincial, Barcelona, Spain
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Barrientos A, Casademont J, Cardellach F, Ardite E, Estivill X, Urbano-Márquez A, Fernández-Checa JC, Nunes V. Qualitative and quantitative changes in skeletal muscle mtDNA and expression of mitochondrial-encoded genes in the human aging process. Biochem Mol Med 1997; 62:165-71. [PMID: 9441868 DOI: 10.1006/bmme.1997.2647] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It has been widely postulated that age-dependent changes in the mitochondrial genetic system may contribute to the human aging process. We recently reported unchanged specific activities of mitochondrial respiratory chain enzymes and a decrease in oxidation capacity of different substrates with aging, due, in part, to some confounding variables such as physical activity or tobacco consumption. The present study deals with age-related changes in muscle mtDNA structure and its biogenesis in humans. We found a low prevalence of mtDNA rearrangements with aging, only detected by PCR. The mtDNA content increased significantly with age (b = 0.0115, P < 0.0001). Also, an unchanged steady-state level of mitochondrial transcripts, a reduced transcription rate (P < 0.0001), and an increase in mitochondrial membrane lipid peroxidation (P < 0.0001) were observed in aging. These data demonstrate that minor structural mtDNA changes appear during the human aging process. By contrast, alterations in mitochondrial homeostasis ultimately producing modifications in mitochondrial biogenesis rates could play a role in the process of human senescence.
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Affiliation(s)
- A Barrientos
- Department of Internal Medicine, Hospital Clinic, University of Barcelona, Spain
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Morales A, García-Ruiz C, Miranda M, Marí M, Colell A, Ardite E, Fernández-Checa JC. Tumor necrosis factor increases hepatocellular glutathione by transcriptional regulation of the heavy subunit chain of gamma-glutamylcysteine synthetase. J Biol Chem 1997; 272:30371-9. [PMID: 9374527 DOI: 10.1074/jbc.272.48.30371] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Tumor necrosis factor (TNF) is an inflammatory cytokine that causes cell injury by generation of oxidative stress. Since glutathione (GSH) is a key cellular antioxidant that detoxifies reactive oxygen species, the purpose of our work was to examine the regulation of cellular GSH, the expression of heavy subunit chain of gamma-glutamylcysteine synthetase (gamma-GCS-HS), and control of intracellular generation of reactive oxygen species in cultured rat hepatocytes treated with TNF. Exposure of cells to TNF (10,000 units/ml) resulted in depletion of cellular GSH levels (50-70%) and overproduction of hydrogen peroxide (2-3-fold) and lipid peroxidation. However, cells treated with lower doses of TNF (250-500 units/ml) exhibited increased levels of GSH (60-80% over control). TNF treatment increased (70-100%) the levels of gamma-GCS-HS mRNA, the catalytic subunit of the regulating enzyme in GSH biosynthesis. Furthermore, intact nuclei isolated from hepatocytes treated with TNF transcribed the gamma-GCS-HS gene to a greater extent than control cells, indicating that TNF regulates gamma-GCS-HS at the transcriptional level. The capacity to synthesize GSH de novo determined in cell-free extracts incubated with GSH precursors was greater (50-70%) in hepatocytes that were treated with TNF; however, the activity of GSH synthetase remained unaltered by TNF treatment indicating that TNF selectively increased the activity of gamma-GCS. Despite activation of nuclear factor-kappaB (NF-kappaB) by TNF, this transcription factor was not required for TNF-induced transcription of gamma-GCS-HS as revealed by deletion constructs of the gamma-GCS-HS promoter subcloned in a chloramphenicol acetyltransferase reporter vector and transfected into HepG2 cells. In contrast, a construct containing AP-1 like/metal response regulatory elements increased chloramphenicol acetyltransferase activity upon exposure to TNF. Thus, TNF increases hepatocellular GSH levels by transcriptional regulation of gamma-GCS-HS gene, probably through AP-1/metal response element-like binding site(s) in its promoter, which may constitute a protective mechanism in the control of oxidative stress induced by inflammatory cytokines.
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Affiliation(s)
- A Morales
- Instituto de Investigaciones Biomédicas, Consejo Superior Investigaciones Científicas and Liver Unit and Servicio de Bioquímica, Department of Medicine, Hospital Clinic i Provincial, Universidad de Barcelona, Barcelona 08036, Spa
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Colell A, García-Ruiz C, Morales A, Ballesta A, Ookhtens M, Rodés J, Kaplowitz N, Fernández-Checa JC. Transport of reduced glutathione in hepatic mitochondria and mitoplasts from ethanol-treated rats: effect of membrane physical properties and S-adenosyl-L-methionine. Hepatology 1997; 26:699-708. [PMID: 9303501 DOI: 10.1002/hep.510260323] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ethanol intake depletes the mitochondrial pool of reduced glutathione (GSH) by impairing the transport of GSH from cytosol into mitochondria. S-Adenosyl-L-methionine (SAM) supplementation of ethanol-fed rats restores the mitochondrial pool of GSH. The purpose of the current study was to determine the effect of ethanol feeding on the kinetic parameters of mitochondrial GSH transport, the fluidity of mitochondria, and the effect of SAM on these changes. Male Sprague-Dawley rats were fed ethanol-liquid diet for 4 weeks supplemented with either SAM or N-acetylcysteine (NAC). SAM-supplementation of ethanol-fed rats restored the mitochondrial GSH pool but NAC administration did not. Kinetic studies of GSH transport in isolated mitochondria revealed two saturable, adenosine triphosphate (ATP)-stimulated components that were affected significantly by chronic ethanol feeding: lowering Vmax (0.22 and 1.6 in ethanol case vs. 0.44 and 2.7 nmol/15 sec/mg protein in controls) for both low and high affinity components with the latter showing an increased Km (15.5 vs. 8.9, mmol/L in ethanol vs. control). Mitochondria from SAM-supplemented ethanol-fed rats showed kinetic features of GSH transport similar to control mitochondria. Determination of membrane fluidity revealed an increased order parameter in ethanol compared with control mitochondria, which was restricted to the polar head groups of the bilayer and was prevented by SAM but not NAC supplementation of ethanol-fed rats. The changes elicited in mitochondria by ethanol were confined to the inner membrane; mitoplasts from ethanol-fed rats showed features similar to those of intact mitochondria such as impaired transport of GSH and increased order parameter. A different mitochondrial transporter, adenosine diphosphate (ADP)/ATP translocator, was unaffected by ethanol feeding. Furthermore, fluidization of mitochondria or mitoplasts from ethanol-fed rats by treatment with a fatty acid derivative restored their ability to transport GSH to control levels. Thus, ethanol-induced impaired transport of GSH into mitochondria is selective, mediated by decreased fluidity of the mitochondrial inner membrane, and prevented by SAM treatment.
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Affiliation(s)
- A Colell
- Instituto Investigaciones Biomédicas, Consejo Superior InvestigacionesCientíficas, Barcelona, Spain
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42
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Fernández-Checa JC, Kaplowitz N, García-Ruiz C, Colell A, Miranda M, Marí M, Ardite E, Morales A. GSH transport in mitochondria: defense against TNF-induced oxidative stress and alcohol-induced defect. Am J Physiol 1997; 273:G7-17. [PMID: 9252504 DOI: 10.1152/ajpgi.1997.273.1.g7] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Mitochondria generate reactive oxygen species (ROS) as byproducts of molecular oxygen consumption in the electron transport chain. Most cellular oxygen is consumed in the cytochrome-c oxidase complex of the respiratory chain, which does not generate reactive species. The ubiquinone pool of complex III of respiration is the major site within the respiratory chain that generates superoxide anion as a result of a single electron transfer to molecular oxygen. Superoxide anion and hydrogen peroxide, derived from the former by superoxide dismutase, are precursor of hydroxyl radical through the participation of transition metals. Glutathione (GSH) in mitochondria is the only defense available to metabolize hydrogen peroxide. A small fraction of the total cellular GSH pool is sequestered in mitochondria by the action of a carrier that transports GSH from the cytosol to the mitochondrial matrix. Mitochondria are not only one of the main cellular sources of ROS, they also are a key target of ROS. Mitochondria are subcellular targets of cytokines, especially tumor necrosis factor (TNF); depletion of GSH in this organelle renders the cell more susceptible to oxidative stress originating in mitochondria. Ceramide generated during TNF signaling leads to increased production of ROS in mitochondria. Chronic ethanol-fed hepatocytes are selectively depleted of GSH in mitochondria due to a defective operation of the carrier responsible for transport of GSH from the cytosol into the mitochondrial matrix. Under these conditions, limitation of the mitochondrial GSH pool represents a critical contributory factor that sensitizes alcoholic hepatocytes to the prooxidant effects of cytokines and prooxidants generated by oxidative metabolism of ethanol. S-adenosyl-L-methionine prevents development of the ethanol-induced defect. The mitochondrial GSH carrier has been functionally expressed in Xenopus laevis oocytes microinjected with mRNA from rat liver. This critical carrier displays functional characteristics distinct from other plasma membrane GSH carriers, such as its ATP dependency, inhibitor specificity, and the size class of mRNA that encode the corresponding carrier, suggesting that the mitochondrial carrier of GSH is a gene product distinct from the plasma membrane transporters.
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Affiliation(s)
- J C Fernández-Checa
- Instituto de Investigaciones Biomédicas, Hospital Clinic i Provincial, Universidad de Barcelona, Spain
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García-Ruiz C, Colell A, Marí M, Morales A, Fernández-Checa JC. Direct effect of ceramide on the mitochondrial electron transport chain leads to generation of reactive oxygen species. Role of mitochondrial glutathione. J Biol Chem 1997; 272:11369-77. [PMID: 9111045 DOI: 10.1074/jbc.272.17.11369] [Citation(s) in RCA: 599] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Ceramide is a sphingolipid that is generated in the signaling of inflammatory cytokines such as tumor necrosis factor (TNF), which exerts many functional roles depending on the cell type where it is produced. Since TNF cytotoxicity is mediated by overproduction of reactive oxygen species from mitochondria, we have examined the role of ceramide in generation of oxidative stress in isolated rat liver mitochondria. The present studies demonstrate that addition of N-acetylsphingosine (C2-ceramide) to mitochondria led to an increase of fluorescence of dihydrorhodamine 123 or dichlorofluorescein-stained mitochondria, indicating formation of hydrogen peroxide. Such effect was significant at 0.25 microM and maximal at 1-5 microM C2, decreasing at greater concentrations. This inductive effect of ceramide was mimicked by N-hexanoylsphingosine at the same concentration range, whereas the immediate precursor of C2, C2-dihydroceramide increased hydrogen peroxide at 1-5 microM. Sphingosine generated hydrogen peroxide at concentrations >/=10 microM, whereas diacylglycerol failed to increase hydrogen peroxide. The increase in hydrogen peroxide induced by C2 was not triggered by mitochondrial permeability transition as C2 did not induce mitochondrial swelling. Blocking electron transport chain at complex I and II prevented the increase in hydrogen peroxide induced by C2; however, interruption of electron flow at complex III by antimycin A potentiated the inductive effect of C2. Depletion of matrix GSH prior to exposure to ceramide resulted in a potentiated increase (2-fold) of hydrogen peroxide generation, leading to lipid peroxidation and loss of activity of respiratory chain complex IV compared with GSH-repleted mitochondria. Mitochondria isolated from TNF-treated cells showed an increase (2-3-fold) in the amount of ceramide compared with mitochondria from untreated cells. These results suggest that mitochondria are a target of ceramide produced in the signaling of TNF whose effect on mitochondrial electron transport chain leads to overproduction of hydrogen peroxide and consequently this phenomena may account for the generation of reactive oxygen species during TNF cytotoxicity.
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Affiliation(s)
- C García-Ruiz
- Instituto Investigaciones Biomédicas, Consejo Superior Investigaciones Científicas, Universidad de Barcelona, Barcelona 08036, Spain
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Abstract
PURPOSE To study the mechanism of lenticular glutathione (GSH) depletion in galactose-fed guinea pigs, with particular reference to correlations between liver and lens GSH, precursor (cysteine) status and GSH synthetic capacities. METHODS Guinea pigs in the ad libitum-fed state were fed powdered guinea pig chow containing 50% galactose for 3 and 14-16 days. Plasma GSH and GSH levels in lens, liver and freshly isolated hepatocytes were determined. Maximal rates of GSH synthesis in liver and lens as well as steady state levels of precursor cysteine were also determined. In separate experiments, linear rate of 35S-cysteine uptake was studied in isolated hepatocytes from control and galactose-fed animals. Lens and liver GSH decreased significantly with galactose feeding. Hepatic GSH showed a dramatic decrease (approximately 83%) as early as day 3 whereas approximately 43% decrease was observed in lens. The maximal GSH synthetic rates (GSH-SR) in the whole lens and liver on days 3 and 14-16 were not different from those of controls. Steady-state levels of cysteine also decreased in both tissues with galactose feeding, and the magnitude of decrease was higher in the liver as compared to the lens. The rate of cysteine uptake in hepatocytes isolated from galactose-fed guinea pigs was significantly lower for the cysteine concentrations studied (10 microM to 1 mM) as compared to control uptake. The decreased steady-state liver GSH and cysteine levels in galactose-fed guinea pigs caused a significant decrease in plasma (and aqueous) GSH concentrations. CONCLUSIONS We concluded that the decrease in lens GSH due to galactose occurs without alterations in the capacity of GSH synthesis, in either lens or liver. It is suggested that decreased hepatic GSH, resulting in reduced plasma GSH levels due to decreased GSH efflux into plasma, may contribute to impairment in plasma to lens GSH transport with galactose. Thus, the functional role of recently identified lens GSH transporters, particularly that of Na(+)-dependent GSH transporter, in galactose-induced cataract formation will be worthy of investigation.
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Affiliation(s)
- R Kannan
- Division of Gastrointestinal and Liver Diseases, University of Southern California School of Medicine 90033, USA
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Goldin E, Ardite E, Elizalde JI, Odriozola A, Panés J, Piqué JM, Fernández-Checa JC. Gastric mucosal damage in experimental diabetes in rats: role of endogenous glutathione. Gastroenterology 1997; 112:855-63. [PMID: 9041247 DOI: 10.1053/gast.1997.v112.pm9041247] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND & AIMS Spontaneous gastric damage occurs in diabetic rats, but the mechanism is unknown. The aim of this study was to assess the role of glutathione metabolism and gastric mucosal blood flow (GMBF) in the development of such spontaneous gastric damage. METHODS Mucosal damage, GMBF, glutathione metabolism, and lipid peroxidation were measured in the stomach of diabetic and control rats. RESULTS Spontaneous gastric damage occurred in fasted diabetic rats 4 weeks after streptozotocin administration or pancreatectomy. This was accompanied by a 50% decrement in mucosal content of glutathione; 48 hours after streptozotocin, the decrement of glutathione was only of 25% and no gastric damage was observed. Fed diabetic rats (4 weeks after streptozotocin) had normal glutathione levels and no damage; however, a 30% glutathione depletion achieved by buthionine-sulfoximine administration promoted significant damage. Gastric glutathione synthetic rate, levels of adenosine triphosphate, oxidized glutathione, and malonyldialdehyde were similar in all groups, whereas cysteine concentration was reduced in fasted diabetic animals. Exogenous cysteine attenuated the gastric damage. GMBF was not influenced by diabetes. CONCLUSIONS Spontaneous gastric damage in fasted diabetic rats seems to be related to glutathione depletion as a result of limited availability of cysteine and not to increased glutathione oxidation. GMBF changes are not involved.
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Affiliation(s)
- E Goldin
- Gastroenterology Department, Hospital Clinic, University of Barcelona, Spain
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Fernández-Checa JC, Kaplowitz N, Colell A, García-Ruiz C. Oxidative stress and alcoholic liver disease. Alcohol Health Res World 1997; 21:321-4. [PMID: 15706743 PMCID: PMC6827680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Toxic substances generated during the metabolism of alcohol in the liver may contribute to the development of alcoholic liver disease. These substances include highly reactive molecules that can destroy vital cell components through a process called oxidation. Cells are protected against oxidation by the action of certain enzymes, vitamins, and other substances, known collectively as antioxidants. An imbalance between oxidants and antioxidants can lead to oxidative stress, characterized by escalating cell damage. Evidence suggests that the major energy-generating structures within cells (i.e., mitochondria) may be especially sensitive to oxidative stress, resulting in diminished energy production. Medications that reduce oxidative stress in mitochondria may ameliorate liver disease.
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Affiliation(s)
- J C Fernández-Checa
- Instituto Investigaciones Biomedicas, Consejo Superior Investigaciones Cientificas and Liver Unit, Hospital Clinic i Provincial, Universidad de Barcelona, Barcelona, Spain
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Fernández-Checa JC, García-Ruiz C, Colell A, Yi JR, Kaplowitz N. Inhibition of rat sinusoidal GSH transporter by thioethers: specificity, sidedness, and kinetics. Am J Physiol 1996; 270:G969-75. [PMID: 8764204 DOI: 10.1152/ajpgi.1996.270.6.g969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In isolated hepatocytes, cystathionine, methionine, and thioether analogues of methionine, cysteine, and homocysteine, including S-adenosyl derivatives, inhibited reduced glutathione (GSH) efflux. The potency of inhibition by thioethers with different S-alkyl moieties was methyl < ethyl < butyryl < aminoethyl < alpha-aminopropionyl. Inhibition of GSH efflux by cystathionine from hepatocytes that were allowed to resynthesize GSH resulted in greater repletion (30-40%) of GSH levels compared with absence of cystathionine. To address unequivocally the sidedness of inhibition, i.e., cis vs. trans, we examined the effect of cystathionine on the activity of GSH transport in Xenopus oocytes expressing the cRNA of cloned rat liver sinusoidal (RsGshT) and canalicular (RcGshT) GSH transporters. Cystathionine trans inhibited efflux of GSH and cis inhibited uptake of GSH by oocytes expressing RsGshT. Conversely, when oocytes expressing RsGshT were loaded with cystathionine, no inhibition of uptake or efflux was observed. The same structural requirement of a thioether bond to exert an inhibitory effect on GSH transport was observed in oocytes expressing RsGshT. Oocytes expressing RsGshT do not transport methionine, whereas oocytes expressing total rat liver mRNA express methionine transport. Inhibition of both GSH efflux from and uptake by oocytes expressing RsGshT exhibited a competitive type of kinetics: cystathionine increased the Michaelis constant for GSH transport (4.5 +/- 0.9 vs. 10 +/- 2.5 mM and 7.5 +/- 0.6 vs. 12.9 +/- 1.5 mM for uptake and efflux, respectively) without affecting the maximal velocity for transport. Thus thioethers such as methionine and cystathionine inhibit the transport of GSH by interacting in a competitive and specific fashion with the sinusoidal GSH transporter without themselves being transported by this carrier.
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Affiliation(s)
- J C Fernández-Checa
- Department of Medicine, Hospital Clinic i Provincial, Universidad de Barcelona, Spain.
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Kaplowitz N, Fernández-Checa JC, Kannan R, Garcia-Ruiz C, Ookhtens M, Yi JR. GSH transporters: molecular characterization and role in GSH homeostasis. Biol Chem Hoppe Seyler 1996; 377:267-73. [PMID: 8828817 DOI: 10.1515/bchm3.1996.377.5.267] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Considerable progress has been made in the last few years in the molecular identification and characterization of hepatic GSH transporter-associated polypeptides. We are now poised to determine their precise mechanisms of action and regulation at the transcriptional and post-translational level. It is also anticipated that molecular characterization of the mitochondrial GSH transporter and sodium GSH co-transporters will be accomplished in the near future. With this information, a more complete understanding of GSH/cysteine homeostasis can be achieved which can be applied to furthering the prevention and treatment of the diseases of oxidative stress, such as aging, HIV, cataract, atherosclerosis, cancer and alcoholic liver disease.
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Affiliation(s)
- N Kaplowitz
- USC Center for Liver Diseases, USC School of Medicine, Los Angeles, 90033-4581, USA
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Abstract
The tripeptide glutathione (GSH) is a key nonprotein thiol that plays multiple critical functional and regulatory roles in cells. Hepatic transport of GSH is a key process in the interorgan homeostasis of GSH. Hepatocellular GSH is available to other extrahepatic organs by its release into blood and bile through the sinusoidal and canalicular GSH carriers, respectively. Their characterization at the molecular level has been recently accomplished using the functional expression cloning strategy utilizing Xenopus laevis oocytes microinjected with the corresponding cRNA from the sinusoidal (RsGshT) and canalicular (RcGshT) clones previously isolated and identified from cDNA libraries constructed from hepatic size-fraction mRNAs expressing separately the sinusoidal and canalicular GSH transporters. These clones of 2.8 and 4.0 kb encode for proteins of 39.9 and 95.8 kD for RsGshT and RcGshT, respectively, with 3 to 5 and 6 to 10 putative membrane-spanning domains. Their tissue distribution reveals that RsGshT is exclusively found in liver, contrasting with the distribution of RcGshT, which is found in nearly all tissues examined. Cellular GSH is also found in the mitochondrial matrix at a concentration similar to that in cytosol. However, mitochondria do not synthesize their own GSH, which originates from the operation of a transport carrier localized within the inner mitochondrial membrane. Its role is critical in maintaining a functionally competent organelle and in cell viability. Expression studies in Xenopus oocytes have allowed the identification of the hepatic mitochondrial GSH carrier (RmGshT), which displays distinct functional features from both RsGshT and RcGshT, such as ATP stimulation and inhibitor specificity, suggesting that RmGshT is encoded by a gene distinct from that of the plasma membrane GSH carriers.
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García-Ruiz C, Colell A, Morales A, Kaplowitz N, Fernández-Checa JC. Role of oxidative stress generated from the mitochondrial electron transport chain and mitochondrial glutathione status in loss of mitochondrial function and activation of transcription factor nuclear factor-kappa B: studies with isolated mitochondria and rat hepatocytes. Mol Pharmacol 1995; 48:825-34. [PMID: 7476912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Mitochondria are an important source of reactive oxygen intermediates because they are the major consumers of molecular oxygen in cells. Respiration is associated with toxicity, which is related to the activation of oxygen to reactive intermediates. The purpose of the present study was to examine the role of reduced glutathione (GSH) in the maintenance of mitochondrial functions during oxidative stress induced through selective inhibition of the complex III segment of the electron transport chain. Hydrogen peroxide monitored by the fluorescence of dichlorofluorescein increased in a time- and dose-dependent manner on incubation of mitochondria with antimycin A (AA), an inhibitor of complex III. However, blockade of complex I or II with rotenone or thenoyltrifluoroacetone, respectively, did not result in accumulation of hydrogen peroxide. Depletion of mitochondrial GSH to 10-20% of control by preincubation with diethylmaleate (0.8 mM) or ethacrynic acid (250 microM) also increased dichlorofluorescein and malondialdehyde levels and resulted in an additional (2-3-fold) increase after AA. Similar results were obtained when mitochondrial GSH depletion was produced by treatment with buthionine L-sulfoximine before mirochondria isolation. The endogenous oxidative stress induced by AA was accompanied by a moderate loss of activity of ATPase complex (77% of control) and complex IV of respiration (75% of control), which was accentuated after depletion of mitochondrial GSH (51% and 45% of control, respectively). Similar results were observed in isolated hepatocytes in which depletion of mitochondrial GSH and AA led to peroxidation and mitochondrial dysfunction. In addition, with electrophoretic mobility shift assay of the transcription factor nuclear factor-kappa B (NF-kappa B), we detected its activation in response to AA (2-3-fold). Depletion of mitochondrial GSH in hepatocytes (20% of control) led to further enhancement of NF-kappa B activation (2-4-fold), which correlated with generation of hydrogen peroxide. Thus, our results suggest that GSH protects mitochondria against the endogenous oxidative stress produced at the ubiquinone site of the electron transport chain. Mitochondrial GSH depletion potentiates oxidant-induced loss of mitochondrial functions. Oxidant stress in mitochondria can promote extramitochondrial activation of NF-kappa B and therefore may affect nuclear gene expression.
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Affiliation(s)
- C García-Ruiz
- Department of Medicine, Hospital Clinic i Provincial, Barcelona, Spain
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