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Chen Z, Wang S, Pottekat A, Duffey A, Jang I, Chang BH, Cho J, Finck BN, Davidson NO, Kaufman RJ. Conditional hepatocyte ablation of PDIA1 uncovers indispensable roles in both APOB and MTTP folding to support VLDL secretion. Mol Metab 2024; 80:101874. [PMID: 38211723 PMCID: PMC10832468 DOI: 10.1016/j.molmet.2024.101874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/04/2024] [Accepted: 01/06/2024] [Indexed: 01/13/2024] Open
Abstract
OBJECTIVES The assembly and secretion of hepatic very low-density lipoprotein (VLDL) plays pivotal roles in hepatic and plasma lipid homeostasis. Protein disulfide isomerase A1 (PDIA1/P4HB) is a molecular chaperone whose functions are essential for protein folding in the endoplasmic reticulum. Here we investigated the physiological requirement in vivo for PDIA1 in maintaining VLDL assembly and secretion. METHODS Pdia1/P4hb was conditionally deleted in adult mouse hepatocytes and the phenotypes characterized. Mechanistic analyses in primary hepatocytes determined how PDIA1 ablation alters MTTP synthesis and degradation as well as altering synthesis and secretion of Apolipoprotein B (APOB), along with complementary expression of intact PDIA1 vs a catalytically inactivated PDIA1 mutant. RESULTS Hepatocyte-specific deletion of Pdia1/P4hb inhibited hepatic MTTP expression and dramatically reduced VLDL production, leading to severe hepatic steatosis and hypolipidemia. Pdia1-deletion did not affect mRNA expression or protein stability of MTTP but rather prevented Mttp mRNA translation. We demonstrate an essential role for PDIA1 in MTTP synthesis and function and show that PDIA1 interacts with APOB in an MTTP-independent manner via its molecular chaperone function to support APOB folding and secretion. CONCLUSIONS PDIA1 plays indispensable roles in APOB folding, MTTP synthesis and activity to support VLDL assembly. Thus, like APOB and MTTP, PDIA1 is an obligatory component of hepatic VLDL production.
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Affiliation(s)
- Zhouji Chen
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA.
| | - Shiyu Wang
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA
| | - Anita Pottekat
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA
| | - Alec Duffey
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA
| | - Insook Jang
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA
| | - Benny H Chang
- Section of Nephrology, Division of Internal Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jaehyung Cho
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Brian N Finck
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nicholas O Davidson
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Randal J Kaufman
- Degenerative Diseases Program, Center for Genetics and Aging Research, Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd, La Jolla CA 92037, USA.
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Fatty Liver Disease-Alcoholic and Non-Alcoholic: Similar but Different. Int J Mol Sci 2022; 23:ijms232416226. [PMID: 36555867 PMCID: PMC9783455 DOI: 10.3390/ijms232416226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/12/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
In alcohol-induced liver disease (ALD) and in non-alcoholic fatty liver disease (NAFLD), there are abnormal accumulations of fat in the liver. This phenomenon may be related to excessive alcohol consumption, as well as the combination of alcohol consumption and medications. There is an evolution from simple steatosis to steatohepatitis, fibrosis and cirrhosis leading to hepatocellular carcinoma (HCC). Hepatic pathology is very similar regarding non-alcoholic fatty liver disease (NAFLD) and ALD. Initially, there is lipid accumulation in parenchyma and progression to lobular inflammation. The morphological changes in the liver mitochondria, perivenular and perisinusoidal fibrosis, and hepatocellular ballooning, apoptosis and necrosis and accumulation of fibrosis may lead to the development of cirrhosis and HCC. Medical history of ethanol consumption, laboratory markers of chronic ethanol intake, AST/ALT ratio on the one hand and features of the metabolic syndrome on the other hand, may help in estimating the contribution of alcohol intake and the metabolic syndrome, respectively, to liver steatosis.
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Di Ciaula A, Bonfrate L, Krawczyk M, Frühbeck G, Portincasa P. Synergistic and Detrimental Effects of Alcohol Intake on Progression of Liver Steatosis. Int J Mol Sci 2022; 23:ijms23052636. [PMID: 35269779 PMCID: PMC8910376 DOI: 10.3390/ijms23052636] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 02/07/2023] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) are the most common liver disorders worldwide and the major causes of non-viral liver cirrhosis in the general population. In NAFLD, metabolic abnormalities, obesity, and metabolic syndrome are the driving factors for liver damage with no or minimal alcohol consumption. ALD refers to liver damage caused by excess alcohol intake in individuals drinking more than 5 to 10 daily units for years. Although NAFLD and ALD are nosologically considered two distinct entities, they show a continuum and exert synergistic effects on the progression toward liver cirrhosis. The current view is that low alcohol use might also increase the risk of advanced clinical liver disease in NAFLD, whereas metabolic factors increase the risk of cirrhosis among alcohol risk drinkers. Therefore, special interest is now addressed to individuals with metabolic abnormalities who consume small amounts of alcohol or who binge drink, for the role of light-to-moderate alcohol use in fibrosis progression and clinical severity of the liver disease. Evidence shows that in the presence of NAFLD, there is no liver-safe limit of alcohol intake. We discuss the epidemiological and clinical features of NAFLD/ALD, aspects of alcohol metabolism, and mechanisms of damage concerning steatosis, fibrosis, cumulative effects, and deleterious consequences which include hepatocellular carcinoma.
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Affiliation(s)
- Agostino Di Ciaula
- Clinica Medica “Augusto Murri”, Department of Biomedical Sciences and Human Oncology, University of Bari Medical School—Piazza Giulio Cesare 11, 70124 Bari, Italy; (A.D.C.); (L.B.)
| | - Leonilde Bonfrate
- Clinica Medica “Augusto Murri”, Department of Biomedical Sciences and Human Oncology, University of Bari Medical School—Piazza Giulio Cesare 11, 70124 Bari, Italy; (A.D.C.); (L.B.)
| | - Marcin Krawczyk
- Department of Medicine II Saarland University Medical Center, Saarland University, 66424 Homburg, Germany;
- Laboratory of Metabolic Liver Diseases, Department of General, Transplant and Liver Surgery, Centre for Preclinical Research, Medical University of Warsaw, 02-091 Warsaw, Poland
| | - Gema Frühbeck
- Department of Endocrinology & Nutrition, Clínica Universidad de Navarra, 31008 Pamplona, Spain;
- Metabolic Research Laboratory, Clínica Universidad de Navarra, 31008 Pamplona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), ISCIII, 31009 Pamplona, Spain
- Obesity and Adipobiology Group, Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31009 Pamplona, Spain
| | - Piero Portincasa
- Clinica Medica “Augusto Murri”, Department of Biomedical Sciences and Human Oncology, University of Bari Medical School—Piazza Giulio Cesare 11, 70124 Bari, Italy; (A.D.C.); (L.B.)
- Correspondence:
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Schnegelberger RD, Lang AL, Arteel GE, Beier JI. Environmental toxicant-induced maladaptive mitochondrial changes: A potential unifying mechanism in fatty liver disease? Acta Pharm Sin B 2021; 11:3756-3767. [PMID: 35024304 PMCID: PMC8727895 DOI: 10.1016/j.apsb.2021.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/29/2021] [Accepted: 08/19/2021] [Indexed: 12/14/2022] Open
Abstract
Occupational and environmental exposures to industrial chemicals are well known to cause hepatotoxicity and liver injury. However, despite extensive evidence showing that exposure can lead to disease, current research approaches and regulatory policies fail to address the possibility that subtle changes caused by low level exposure to chemicals may also enhance preexisting conditions. In recent years, the conceptual understanding of the contribution of environmental chemicals to liver disease has progressed significantly. Mitochondria are often target of toxicity of environmental toxicants resulting in multisystem disorders involving different cells, tissues, and organs. Here, we review persistent maladaptive changes to mitochondria in response to environmental toxicant exposure as a mechanism of hepatotoxicity. With better understanding of the mechanism(s) and risk factors that mediate the initiation and progression of toxicant-induced liver disease, rational targeted therapy can be developed to better predict risk, as well as to treat or prevent this disease.
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Affiliation(s)
- Regina D. Schnegelberger
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Anna L. Lang
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Gavin E. Arteel
- Department of Medicine, Division of Gastroenterology, Hepatology & Nutrition, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Juliane I. Beier
- Department of Medicine, Division of Gastroenterology, Hepatology & Nutrition, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Department of Environmental & Occupational Health, University of Pittsburgh, Pittsburgh, PA 15213, USA
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Rungratanawanich W, Qu Y, Wang X, Essa MM, Song BJ. Advanced glycation end products (AGEs) and other adducts in aging-related diseases and alcohol-mediated tissue injury. Exp Mol Med 2021; 53:168-188. [PMID: 33568752 PMCID: PMC8080618 DOI: 10.1038/s12276-021-00561-7] [Citation(s) in RCA: 120] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 01/30/2023] Open
Abstract
Advanced glycation end products (AGEs) are potentially harmful and heterogeneous molecules derived from nonenzymatic glycation. The pathological implications of AGEs are ascribed to their ability to promote oxidative stress, inflammation, and apoptosis. Recent studies in basic and translational research have revealed the contributing roles of AGEs in the development and progression of various aging-related pathological conditions, such as diabetes, cardiovascular complications, gut microbiome-associated illnesses, liver or neurodegenerative diseases, and cancer. Excessive chronic and/or acute binge consumption of alcohol (ethanol), a widely consumed addictive substance, is known to cause more than 200 diseases, including alcohol use disorder (addiction), alcoholic liver disease, and brain damage. However, despite the considerable amount of research in this area, the underlying molecular mechanisms by which alcohol abuse causes cellular toxicity and organ damage remain to be further characterized. In this review, we first briefly describe the properties of AGEs: their formation, accumulation, and receptor interactions. We then focus on the causative functions of AGEs that impact various aging-related diseases. We also highlight the biological connection of AGE-alcohol-adduct formations to alcohol-mediated tissue injury. Finally, we describe the potential translational research opportunities for treatment of various AGE- and/or alcohol-related adduct-associated disorders according to the mechanistic insights presented.
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Affiliation(s)
- Wiramon Rungratanawanich
- grid.420085.b0000 0004 0481 4802Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, 9000 Rockville Pike, Bethesda, MD 20892 USA
| | - Ying Qu
- grid.420085.b0000 0004 0481 4802Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, 9000 Rockville Pike, Bethesda, MD 20892 USA
| | - Xin Wang
- Neuroapoptosis Drug Discovery Laboratory, Department of Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, 60 Fenwood Road, Boston, MA 02115 USA
| | - Musthafa Mohamed Essa
- grid.412846.d0000 0001 0726 9430Department of Food Science and Nutrition, Aging and Dementia Research Group, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khoud, Muscat, Oman ,grid.412846.d0000 0001 0726 9430Aging and Dementia Research Group, Sultan Qaboos University, Muscat, Oman
| | - Byoung-Joon Song
- grid.420085.b0000 0004 0481 4802Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, 9000 Rockville Pike, Bethesda, MD 20892 USA
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Guo FF, Xiao M, Wang SY, Zeng T, Cheng L, Xie Q. Downregulation of mitogen-activated protein kinases (MAPKs) in chronic ethanol-induced fatty liver. Toxicol Mech Methods 2020; 30:407-416. [PMID: 32237978 DOI: 10.1080/15376516.2020.1747126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Mitogen-activated protein kinases (MAPKs) are versatile proteins that have been suggested to be involved in the regulation of lipid metabolism. This study was designed to investigate the responses of MAPK signaling to chronic ethanol exposure in vivo and in vitro, and try to explore its role in the pathogenesis of alcoholic fatty liver (AFL). Mice were fed with Lieber-Decarli liquid diet (5% ethanol, w/v) for 4 weeks to induce fatty liver, and the chronological changes of MAPK phosphorylation were measured using western blotting. We found that chronic ethanol feeding led to accumulation of triglyceride (TG), decreased phosphorylation of MAPKs, decreased protein level of peroxisomal proliferator activation receptor α (PPARα), and increased protein expression of cytochrome P4502E1 (CYP2E1) in mice liver. In vitro study showed that overexpression of CYP2E1 blunted the response of MAPKs to ethanol, and MAPK phosphatase 1 (MKP-1) knockdown by siRNA led to upregulation of PPARα protein level. Lastly, epidermal growth factor (EGF), a well-known MAPK activator, significantly suppressed chronic ethanol-induced hepatic fat accumulation and decline of PPARα expression in mice liver. Collectively, MAPK suppression, possibly due to the activation of hepatic CYP2E1, may be involved in chronic ethanol-induced hepatic steatosis.
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Affiliation(s)
- Fang-Fang Guo
- Department of Pharmacy, Qilu Hospital of Shandong University, Jinan, China
| | - Mo Xiao
- Institute of Toxicology, School of Public Health, Shandong University, Jinan, China
| | - Shao-Yi Wang
- Department of Orthopaedic Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Tao Zeng
- Institute of Toxicology, School of Public Health, Shandong University, Jinan, China
| | - Lei Cheng
- Department of Orthopaedic Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Qing Xie
- Department of Pharmacy, Qilu Hospital of Shandong University, Jinan, China
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Assiri MA, Ali HR, Marentette JO, Yun Y, Liu J, Hirschey MD, Saba LM, Harris PS, Fritz KS. Investigating RNA expression profiles altered by nicotinamide mononucleotide therapy in a chronic model of alcoholic liver disease. Hum Genomics 2019; 13:65. [PMID: 31823815 PMCID: PMC6902345 DOI: 10.1186/s40246-019-0251-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 11/19/2019] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Chronic alcohol consumption is a significant cause of liver disease worldwide. Several biochemical mechanisms have been linked to the initiation and progression of alcoholic liver disease (ALD) such as oxidative stress, inflammation, and metabolic dysregulation, including the disruption of NAD+/NADH. Indeed, an ethanol-mediated reduction in hepatic NAD+ levels is thought to be one factor underlying ethanol-induced steatosis, oxidative stress, steatohepatitis, insulin resistance, and inhibition of gluconeogenesis. Therefore, we applied a NAD+ boosting supplement to investigate alterations in the pathogenesis of early-stage ALD. METHODS To examine the impact of NAD+ therapy on the early stages of ALD, we utilized nicotinamide mononucleotide (NMN) at 500 mg/kg intraperitoneal injection every other day, for the duration of a Lieber-DeCarli 6-week chronic ethanol model in mice. Numerous strategies were employed to characterize the effect of NMN therapy, including the integration of RNA-seq, immunoblotting, and metabolomics analysis. RESULTS Our findings reveal that NMN therapy increased hepatic NAD+ levels, prevented an ethanol-induced increase in plasma ALT and AST, and changed the expression of 25% of the genes that were modulated by ethanol metabolism. These genes were associated with a number of pathways including the MAPK pathway. Interestingly, our analysis revealed that NMN treatment normalized Erk1/2 signaling and prevented an induction of Atf3 overexpression. CONCLUSIONS These findings reveal previously unreported mechanisms by which NMN supplementation alters hepatic gene expression and protein pathways to impact ethanol hepatotoxicity in an early-stage murine model of ALD. Overall, our data suggest further research is needed to fully characterize treatment paradigms and biochemical implications of NAD+-based interventions.
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Affiliation(s)
- Mohammed A Assiri
- Department of Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Hadi R Ali
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - John O Marentette
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Youngho Yun
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Juan Liu
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, 27710, USA
| | - Matthew D Hirschey
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, 27710, USA.,Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University Medical Center, Durham, NC, 27710, USA
| | - Laura M Saba
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Peter S Harris
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Kristofer S Fritz
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045, USA.
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Tangudu NK, Buth N, Strnad P, Cirstea IC, Spasić MV. Deregulation of Hepatic Mek1/2⁻Erk1/2 Signaling Module in Iron Overload Conditions. Pharmaceuticals (Basel) 2019; 12:ph12020070. [PMID: 31067696 PMCID: PMC6631327 DOI: 10.3390/ph12020070] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/30/2019] [Accepted: 05/05/2019] [Indexed: 02/07/2023] Open
Abstract
The liver, through the production of iron hormone hepcidin, controls body iron levels. High liver iron levels and deregulated hepcidin expression are commonly observed in many liver diseases including highly prevalent genetic iron overload disorders. In spite of a number of breakthrough investigations into the signals that control hepcidin expression, little progress has been made towards investigations into intracellular signaling in the liver under excess of iron. This study examined hepatic signaling pathways underlying acquired and genetic iron overload conditions. Our data demonstrate that hepatic iron overload associates with a decline in the activation of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (Erk) kinase (Mek1/2) pathway by selectively affecting the phosphorylation of Erk1/2. We propose that Mek1/2-Erk1/2 signaling is uncoupled from iron-Bmp-Smad-mediated hepcidin induction and that it may contribute to a number of liver pathologies in addition to toxic effects of iron. We believe that our findings will advance the understanding of cellular signaling events in the liver during iron overload of different etiologies.
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Affiliation(s)
- Naveen Kumar Tangudu
- Institute of Comparative Molecular Endocrinology, University of Ulm, Ulm 89081, Germany; (N.K.T.); (N.B.); (I.C.C.)
| | - Nils Buth
- Institute of Comparative Molecular Endocrinology, University of Ulm, Ulm 89081, Germany; (N.K.T.); (N.B.); (I.C.C.)
| | - Pavel Strnad
- Department of Medicine III and IZKF, University Hospital Aachen, Aachen 52074, Germany;
| | - Ion C. Cirstea
- Institute of Comparative Molecular Endocrinology, University of Ulm, Ulm 89081, Germany; (N.K.T.); (N.B.); (I.C.C.)
| | - Maja Vujić Spasić
- Institute of Comparative Molecular Endocrinology, University of Ulm, Ulm 89081, Germany; (N.K.T.); (N.B.); (I.C.C.)
- Correspondence: ; Tel.: +49-731-50-32635
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Chen L, Lang AL, Poff GD, Ding WX, Beier JI. Vinyl chloride-induced interaction of nonalcoholic and toxicant-associated steatohepatitis: Protection by the ALDH2 activator Alda-1. Redox Biol 2019; 24:101205. [PMID: 31026768 PMCID: PMC6479707 DOI: 10.1016/j.redox.2019.101205] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/10/2019] [Accepted: 04/14/2019] [Indexed: 12/20/2022] Open
Abstract
Vinyl chloride (VC), an abundant environmental contaminant causes steatohepatitis at high levels, but is considered safe at lower (i.e., sub-OSHA) levels. However, we have previously shown that even lower VC levels exacerbate experimental nonalcoholic fatty liver disease (NAFLD) caused by high-fat diet (HFD). Mitochondrial oxidative injury and subsequent metabolic dysfunction appeared to play key roles in mediating this interaction. Mitochondrial aldehyde dehydrogenase 2 (ALDH2) serves as a key line of defense against endogenous and exogenous reactive aldehydes. The current study therefore tests the hypothesis that allosteric activation of ALDH2 with Alda-1 will protect against VC-enhanced NAFLD. Mice were exposed to low VC concentrations (<1 ppm), or room air for 6 h/day, 5 days/week for 12 weeks, while on HFD or low-fat control diet (LFD). Some mice received Alda-1 (20 mg/kg i.p., 3 × /week) for the last 3 weeks of diet/VC exposure. Indices of liver injury, oxidative stress, metabolic and mitochondrial (dys)function were measured. As observed previously, low-dose VC did not cause liver injury in control mice; while liver injury caused by HFD was enhanced by VC. VC decreased hepatic ALDH2 activity of mice fed HFD. Alda-1 attenuated oxidative stress, liver injury, and dysmetabolism in mice exposed to HFD+VC under these conditions. Importantly, alterations in mitochondrial function caused by VC and HFD were diminished by Alda-1. Previous studies have indicated that liver injury caused by HFD is mediated, at least in part, by enhanced mitochondrial autophagy (mitophagy). Here, Alda-1 suppressed PINK1/PARKIN-mediated mitophagy. Taken together, these results support the hypothesis that ALDH2 is a critical defense against mitochondrial injury caused by VC in experimental NAFLD. The ALDH2 activator Alda-1 conferred protection against liver damage under these conditions, most likely via increasing clearance of aldehydes and preserving mitochondrial respiratory function. VC, combined with HFD impairs ALDH2 function, causing an accumulation of endogenous aldehydes and oxidative stress in vivo. VC metabolite chloroacetaldehyde directly blocks ALDH2 activity in vitro. Alda-1 treatment reverses pre-established liver injury, oxidative stress and metabolic dysregulation caused by VC and HFD. Alda-1 increases overall autophagy caused by VC+HFD, but decreases mitophagy, likely to preserve mitochondrial function.
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Affiliation(s)
- Liya Chen
- Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA; Hepatobiology and Toxicology Program, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA; University of Louisville Alcohol Research Center, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA.
| | - Anna L Lang
- Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA; Hepatobiology and Toxicology Program, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA; University of Louisville Alcohol Research Center, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA.
| | - Gavin D Poff
- Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA; Hepatobiology and Toxicology Program, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA; University of Louisville Alcohol Research Center, University of Louisville Health Sciences Center, Louisville, KY, 40202, USA.
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
| | - Juliane I Beier
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
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10
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Aldehyde-Induced DNA and Protein Adducts as Biomarker Tools for Alcohol Use Disorder. Trends Mol Med 2018; 24:144-155. [PMID: 29422263 DOI: 10.1016/j.molmed.2017.12.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 12/08/2017] [Accepted: 12/10/2017] [Indexed: 02/06/2023]
Abstract
Alcohol use disorder (AUD) screening frequently involves questionnaires complemented by laboratory work to monitor alcohol use and/or evaluate AUD-associated complications. Here we suggest that measuring aldehyde-induced DNA and protein adducts produced during alcohol metabolism may lead to earlier detection of AUD and AUD-associated complications compared with existing biomarkers. Use of aldehyde-induced adducts to monitor AUD may also be important when considering that approximately 540 million people bear a genetic variant of aldehyde dehydrogenase 2 (ALDH2) predisposing this population to aldehyde-induced toxicity with alcohol use. We posit that measuring aldehyde-induced adducts may provide a means to improve precision medicine approaches, taking into account lifestyle choices and genetics to evaluate AUD and AUD-associated complications.
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11
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Yang R, Guan MJ, Zhao N, Li MJ, Zeng T. Roles of extrahepatic lipolysis and the disturbance of hepatic fatty acid metabolism in TNF-α -induced hepatic steatosis. Toxicology 2018; 411:172-180. [PMID: 30359672 DOI: 10.1016/j.tox.2018.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/16/2018] [Accepted: 10/20/2018] [Indexed: 12/20/2022]
Abstract
Our previous study showed that both Kupffer cell eliminator (GdCl3) and tumor necrosis factor α (TNF-α) receptor antagonist (etanercept) could partially attenuate binge drinking-induced liver steatosis. Herein, we extended the study by directly investigating the roles of TNF-α on the hepatic fat levels in mice and in HepG2 cells, and explored the underlying mechanisms. SPF male ICR mice were exposed to TNF-α (0.166 mg/kg body weight) with or without phenylisopropyl adenosine (PIA, an anti-lipolytic drug) for 1.5, 3, 6, and 24 h. We found that TNF-α treatment resulted in hepatic triglyceride (TG) elevation at 6 h time point, which was blocked by PIA. TNF-α led to the activation of extrahepatic lipolysis demonstrated by the increase of serum free fatty acid (FFA) level, and the increased protein levels of adipose triglyceride lipase (ATGL) and phosphorylated hormone-sensitive lipase (HSL) in mice epididymal adipose tissues, but had no significant effects on the protein levels of sterol regulatory element binding protein 1c (SREBP-1c) and peroxisomal proliferator activation receptor α (PPAR-α) in mice liver. The in vitro study showed TNF-α treatment could not result in elevation of TG in HepG2 cells, although it indeed brought about a slight activation of SREBP-1c. These results support the hypothesis that TNF-α might make a small contribution to ethanol-induced fatty liver by stimulating extrahepatic lipolysis.
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Affiliation(s)
- Rui Yang
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China
| | - Min-Jie Guan
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China
| | - Ning Zhao
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China
| | - Ming-Jun Li
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China
| | - Tao Zeng
- Institute of Toxicology, School of Public Health, Shandong University, 44 Wenhua West Road, Shandong Province, Jinan City, 250012, PR China.
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12
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Shearn CT, Saba LM, Roede JR, Orlicky DJ, Shearn AH, Petersen DR. Differential carbonylation of proteins in end-stage human fatty and nonfatty NASH. Free Radic Biol Med 2017; 113:280-290. [PMID: 28988798 PMCID: PMC5704928 DOI: 10.1016/j.freeradbiomed.2017.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 10/02/2017] [Accepted: 10/04/2017] [Indexed: 02/06/2023]
Abstract
OBJECTIVE In the liver, a contributing factor in the pathogenesis of non-alcoholic fatty liver disease is oxidative stress leading to the accumulation of highly reactive electrophilic α/β unsaturated aldehydes. The objective of this study was to determine if significant differences were evident when evaluating carbonylation in human end-stage fatty nonalcoholic steatohepatitis (fNASH) compared to end-stage nonfatty NASH (nfNASH). METHODS Using hepatic tissue obtained from healthy humans and patients diagnosed with end stage nfNASH or fNASH, overall carbonylation was assessed by immunohistochemistry (IHC) and LC-MS/MS followed by bioinformatics. RESULTS Picrosirius red staining revealed extensive fibrosis in both fNASH and nfNASH which corresponded with increased reactive aldehyde staining. Although significantly elevated when compared to normal hepatic tissue, no significant differences in overall carbonylation and fibrosis were evident when comparing fNASH with nfNASH. Examining proteins that are critical for anti-oxidant defense revealed elevated expression of thioredoxin, thioredoxin interacting protein, glutathione S-transferase p1 and mitochondrial superoxide dismutase in human NASH. As important, using immunohistochemistry, significant colocalization of the aforementioned proteins occurred in cytokeratin 7 positive cells indicating that they are part of the ductular reaction. Expression of catalase and Hsp70 decreased in both groups when compared to normal human liver. Mass spectrometric analysis revealed a total of 778 carbonylated proteins. Of these, 194 were common to all groups, 124 unique to tissue prepared from healthy individuals, 357 proteins exclusive to NASH, 124 proteins distinct to samples from patients with fNASH and 178 unique to nfNASH. Using functional enrichment analysis of hepatic carbonylated proteins revealed a propensity for increased carbonylation of proteins regulating cholesterol and Huntington's disease related pathways occurred in nfNASH. Examining fNASH, increased carbonylation was evident in proteins regulating Rho cytoskeletal pathways, nicotinic acetylcholine receptor signaling and chemokine/cytokine inflammatory pathways. Using LC-MS/MS analysis and trypsin digests, sites of carbonylation were identified on peptides isolated from vimentin, endoplasmin and serum albumin in nfNASH and fNASH respectively. CONCLUSIONS These results indicate that cellular factors regulating mechanisms of protein carbonylation may be different depending on pathological diagnosis of NASH. Furthermore these studies are the first to use LC-MS/MS analysis of carbonylated proteins in human NAFLD and explore possible mechanistic links with end stage cirrhosis due to fatty liver disease and the generation of reactive aldehydes.
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Affiliation(s)
- Colin T Shearn
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States.
| | - Laura M Saba
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States
| | - James R Roede
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States
| | - David J Orlicky
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States
| | - Alisabeth H Shearn
- Alpine Achievement Systems, Inc., 9635 Maroon Circle, Suite 120, Englewood, CO 80112, United States
| | - Dennis R Petersen
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, United States
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13
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Ding L, Wo L, Du Z, Tang L, Song Z, Dou X. Danshen protects against early-stage alcoholic liver disease in mice via inducing PPARα activation and subsequent 4-HNE degradation. PLoS One 2017; 12:e0186357. [PMID: 29020055 PMCID: PMC5636149 DOI: 10.1371/journal.pone.0186357] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/30/2017] [Indexed: 12/16/2022] Open
Abstract
Alcoholic liver disease (ALD) is a type of chronic liver disease caused by long-term heavy ethanol consumption. Danshen is one of the most commonly used substances in traditional Chinese medicine and has been widely used for the treatment of various diseases, and most frequently, the ALD. The current study aims to determine the potential beneficial effect of Danshen administration on ALD and to clarify the underlying molecular mechanisms. Danshen administration improved liver pathologies of ALD, attenuated alcohol-induced increment of hepatic 4-Hydroxynonenal (4-HNE) formation, and prevented hepatic Peroxisome proliferators activated receptor alpha (PPARα) suppression in response to chronic alcohol consumption. Cell culture studies revealed that both hepatoprotective effect and increased intracellular 4-HNE clearance instigated by Danshen supplementation are PPARα-dependent. In conclusion, Danshen administration can protect against ALD via inducing PPARα activation and subsequent 4-HNE degradation.
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Affiliation(s)
- Lei Ding
- College of Life Science, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, P. R. China
| | - Like Wo
- Zhejiang Provincial Hospital of Traditional Chinese Medical, Hangzhou, P. R. China
| | - Zhongyan Du
- Zhejiang Chinese Medical University, Hangzhou, Zhejiang, P. R. China
| | - Lihua Tang
- College of Life Science, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, P. R. China
| | - Zhenyuan Song
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Xiaobing Dou
- College of Life Science, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, P. R. China
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14
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Zeng T, Zhang CL, Zhao N, Guan MJ, Xiao M, Yang R, Zhao XL, Yu LH, Zhu ZP, Xie KQ. Impairment of Akt activity by CYP2E1 mediated oxidative stress is involved in chronic ethanol-induced fatty liver. Redox Biol 2017; 14:295-304. [PMID: 28987868 PMCID: PMC5633250 DOI: 10.1016/j.redox.2017.09.018] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 09/24/2017] [Indexed: 12/30/2022] Open
Abstract
Protein kinase B (PKB/Akt) plays important roles in the regulation of lipid homeostasis, and impairment of Akt activity has been demonstrated to be involved in the development of non-alcoholic fatty liver disease (NAFLD). Previous studies suggest that cytochrome P4502E1 (CYP2E1) plays causal roles in the pathogenesis of alcoholic fatty liver (AFL). We hypothesized that Akt activity might be impaired due to CYP2E1-induced oxidative stress in chronic ethanol-induced hepatic steatosis. In this study, we found that chronic ethanol-induced hepatic steatosis was accompanied with reduced phosphorylation of Akt at Thr308 in mice liver. Chronic ethanol exposure had no effects on the protein levels of phosphatidylinositol 3 kinase (PI3K) and phosphatase and tensin homologue deleted on chromosome ten (PTEN), and led to a slight decrease of phosphoinositide-dependent protein kinase 1 (PDK-1) protein level. Ethanol exposure resulted in increased levels of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE)-Akt adducts, which was significantly inhibited by chlormethiazole (CMZ), an efficient CYP2E1 inhibitor. Interestingly, N-acetyl-L-cysteine (NAC) significantly attenuated chronic ethanol-induced hepatic fat accumulation and the decline of Akt phosphorylation at Thr308. In the in vitro studies, Akt phosphorylation was suppressed in CYP2E1-expressing HepG2 (CYP2E1-HepG2) cells compared with the negative control HepG2 (NC-HepG2) cells, and 4-HNE treatment led to significant decrease of Akt phosphorylation at Thr308 in wild type HepG2 cells. Lastly, pharmacological activation of Akt by insulin-like growth factor-1 (IGF-1) significantly alleviated chronic ethanol-induced fatty liver in mice. Collectively, these results indicate that CYP2E1-induced oxidative stress may be responsible for ethanol-induced suppression of Akt phosphorylation and pharmacological modulation of Akt in liver may be an effective strategy for the treatment of ethanol-induced fatty liver.
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Affiliation(s)
- Tao Zeng
- Institute of Toxicology, School of Public Health, Shandong University, China.
| | - Cui-Li Zhang
- Institute of Toxicology, School of Public Health, Shandong University, China
| | - Ning Zhao
- Institute of Toxicology, School of Public Health, Shandong University, China
| | - Min-Jie Guan
- Institute of Toxicology, School of Public Health, Shandong University, China
| | - Mo Xiao
- Institute of Toxicology, School of Public Health, Shandong University, China
| | - Rui Yang
- Institute of Toxicology, School of Public Health, Shandong University, China
| | - Xiu-Lan Zhao
- Institute of Toxicology, School of Public Health, Shandong University, China
| | - Li-Hua Yu
- Institute of Toxicology, School of Public Health, Shandong University, China
| | - Zhen-Ping Zhu
- Institute of Toxicology, School of Public Health, Shandong University, China
| | - Ke-Qin Xie
- Institute of Toxicology, School of Public Health, Shandong University, China.
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15
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Ji Y, Dai Z, Wu G, Wu Z. 4-Hydroxy-2-nonenal induces apoptosis by activating ERK1/2 signaling and depleting intracellular glutathione in intestinal epithelial cells. Sci Rep 2016; 6:32929. [PMID: 27620528 PMCID: PMC5020658 DOI: 10.1038/srep32929] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/16/2016] [Indexed: 12/11/2022] Open
Abstract
Excessive reactive oxygen species (ROS) induces oxidative damage to cellular constituents, ultimately leading to induction of apoptotic cell death and the pathogenesis of various diseases. The molecular mechanisms for the action of ROS in intestinal diseases remain poorly defined. Here, we reported that 4-hydroxy-2-nonenal (4-HNE) treatment led to capses-3-dependent apoptosis accompanied by increased intracellular ROS level and reduced glutathione concentration in intestinal epithelial cells. These effects of 4-HNE were markedly abolished by the antioxidant L-cysteine derivative N-acetylcysteine (NAC). Further studies demonstrated that the protective effect of NAC was associated with restoration of intracellular redox state by Nrf2-related regulation of expression of genes involved in intracellular glutathione (GSH) biosynthesis and inactivation of 4-HNE-induced phosphorylation of extracellular signal-regulated protein kinases (ERK1/2). The 4-HNE-induced ERK1/2 activation was mediated by repressing mitogen-activated protein kinase phosphatase-1 (MKP-1), a negative regulator of ERK1/2, through a proteasome-dependent degradation mechanism. Importantly, either overexpression of MKP-1 or NAC treatment blocked 4-HNE-induced MKP-1 degradation, thereby protecting cell from apoptosis. These novel findings provide new insights into a functional role of MKP-1 in oxidative stress-induced cell death by regulating ERK1/2 MAP kinase in intestinal epithelial cells.
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Affiliation(s)
- Yun Ji
- State key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China
| | - Zhaolai Dai
- State key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China
| | - Guoyao Wu
- State key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China.,Department of Animal Science, Texas A&M University, College Station, TX 77843, USA
| | - Zhenlong Wu
- State key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing, 100193, P. R. China
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16
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Glade MJ, Meguid MM. A Glance At … ethanol consumption, GSH suppression, and oxidative liver damage. Nutrition 2016; 33:199-203. [PMID: 27644136 DOI: 10.1016/j.nut.2016.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 07/09/2016] [Indexed: 02/07/2023]
Affiliation(s)
| | - Michael M Meguid
- Professor Emeritus, Surgery, Neuroscience and Nutrition, Department of Surgery, University Hospital, Upstate Medical University, Syracuse, New York
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17
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Stiuso P, Bagarolo ML, Ilisso CP, Vanacore D, Martino E, Caraglia M, Porcelli M, Cacciapuoti G. Protective Effect of Tyrosol and S-Adenosylmethionine against Ethanol-Induced Oxidative Stress of Hepg2 Cells Involves Sirtuin 1, P53 and Erk1/2 Signaling. Int J Mol Sci 2016; 17:ijms17050622. [PMID: 27128904 PMCID: PMC4881448 DOI: 10.3390/ijms17050622] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 01/18/2023] Open
Abstract
Oxidative stress plays a major role in ethanol-induced liver damage, and agents with antioxidant properties are promising as therapeutic opportunities in alcoholic liver disease. In the present work, we investigated the effect of S-adenosylmethionine (AdoMet), Tyrosol (Tyr), and their combination on HepG2 cells exposed to ethanol exploring the potential molecular mechanisms. We exposed HepG2 cells to 1 M ethanol for 4 and 48 h; thereafter, we recorded a decreased cell viability, increase of intracellular reactive oxygen species (ROS) and lipid accumulation, and the release into culture medium of markers of liver disease such as triacylglycerol, cholesterol, transaminases, albumin, ferritin, and homocysteine. On the other hand, AdoMet and Tyrosol were able to attenuate or antagonize these adverse changes induced by acute exposure to ethanol. The protective effects were paralleled by increased Sirtuin 1 protein expression and nuclear translocation and increased ERK1/2 phosphorylation that were both responsible for the protection of cells from apoptosis. Moreover, AdoMet increased p53 and p21 expression, while Tyrosol reduced p21 expression and enhanced the expression of uncleaved caspase 3 and 9, suggesting that its protective effect may be related to the inhibition of the apoptotic machinery. Altogether, our data show that AdoMet and Tyrosol exert beneficial effects in ethanol-induced oxidative stress in HepG2 cells and provide a rationale for their potential use in combination in the prevention of ethanol-induced liver damage.
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Affiliation(s)
- Paola Stiuso
- Department of Biochemistry, Biophysics, and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Maria Libera Bagarolo
- Department of Biochemistry, Biophysics, and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Concetta Paola Ilisso
- Department of Biochemistry, Biophysics, and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Daniela Vanacore
- Department of Biochemistry, Biophysics, and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Elisa Martino
- Department of Biochemistry, Biophysics, and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Michele Caraglia
- Department of Biochemistry, Biophysics, and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Marina Porcelli
- Department of Biochemistry, Biophysics, and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
| | - Giovanna Cacciapuoti
- Department of Biochemistry, Biophysics, and General Pathology, Second University of Naples, Via L. De Crecchio 7, 80138 Naples, Italy.
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18
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Shearn CT, Orlicky DJ, Saba LM, Shearn AH, Petersen DR. Increased hepatocellular protein carbonylation in human end-stage alcoholic cirrhosis. Free Radic Biol Med 2015; 89:1144-53. [PMID: 26518673 PMCID: PMC4762037 DOI: 10.1016/j.freeradbiomed.2015.10.420] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 10/20/2015] [Accepted: 10/25/2015] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Oxidative stress is a significant contributing factor in the pathogenesis of alcoholic liver disease (ALD). In the murine models of chronic alcohol consumption, induction of oxidative stress results in increased peroxidation of polyunsaturated fatty acids to form highly reactive electrophilic α/β unsaturated aldehydes that post-translationally modify proteins altering activity. Data are presented here suggesting that oxidative stress and the resulting carbonylation of hepatic proteins is an ongoing process involved in alcohol-induced cirrhosis. METHODS Using age-matched pooled hepatic tissue obtained from healthy humans and patients with end stage cirrhotic ALD, overall carbonylation was assessed by immunohistochemistry and LC-MS/MS of streptavidin purified hepatic whole cell extracts treated with biotin hydrazide. Identified carbonylated proteins were further evaluated using bioinformatics analyses. RESULTS Using immunohistochemistry and Western blotting, protein carbonylation was increased in end stage ALD occurring primarily in hepatocytes. Mass spectrometric analysis revealed a total of 1224 carbonylated proteins in normal hepatic and end-stage alcoholic cirrhosis tissue. Of these, 411 were unique to cirrhotic ALD, 261 unique to normal hepatic tissue and 552 common to both groups. Bioinformatic pathway analysis of hepatic carbonylated proteins revealed a propensity of long term EtOH consumption to increase post-translational carbonylation of proteins involved in glutathione homeostatic, glycolytic and cytoskeletal pathways. Western analysis revealed increased expression of GSTA4 and GSTπ in human ALD. Using LC-MS/MS analysis, a nonenaldehyde post-translational modification was identified on Lysine 235 of the cytoskeletal protein vimentin in whole cell extracts prepared from human end stage ALD hepatic tissue. CONCLUSIONS These studies are the first to use LC-MS/MS analysis of carbonylated proteins in human ALD and begin exploring possible mechanistic links with end-stage alcoholic cirrhosis and oxidative stress.
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Affiliation(s)
- C T Shearn
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver Anschutz Medical Campus, 12850 East Montview Blvd Box C238, Building V20 Room 2131, Aurora, CO 80045, United States.
| | - D J Orlicky
- Department of Pathology, School of Medicine, University of Colorado Denver Anschutz Medical Campus, Aurora, CO 80045, United States
| | - L M Saba
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver Anschutz Medical Campus, 12850 East Montview Blvd Box C238, Building V20 Room 2131, Aurora, CO 80045, United States
| | - A H Shearn
- Alpine Achievement Systems, Inc., 9635 Maroon Circle, Suite 120, Englewood, CO 80112, United States
| | - Dennis R Petersen
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver Anschutz Medical Campus, 12850 East Montview Blvd Box C238, Building V20 Room 2131, Aurora, CO 80045, United States.
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19
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Sapkota M, Wyatt TA. Alcohol, Aldehydes, Adducts and Airways. Biomolecules 2015; 5:2987-3008. [PMID: 26556381 PMCID: PMC4693266 DOI: 10.3390/biom5042987] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/13/2015] [Accepted: 10/16/2015] [Indexed: 12/20/2022] Open
Abstract
Drinking alcohol and smoking cigarettes results in the formation of reactive aldehydes in the lung, which are capable of forming adducts with several proteins and DNA. Acetaldehyde and malondialdehyde are the major aldehydes generated in high levels in the lung of subjects with alcohol use disorder who smoke cigarettes. In addition to the above aldehydes, several other aldehydes like 4-hydroxynonenal, formaldehyde and acrolein are also detected in the lung due to exposure to toxic gases, vapors and chemicals. These aldehydes react with nucleophilic targets in cells such as DNA, lipids and proteins to form both stable and unstable adducts. This adduction may disturb cellular functions as well as damage proteins, nucleic acids and lipids. Among several adducts formed in the lung, malondialdehyde DNA (MDA-DNA) adduct and hybrid malondialdehyde-acetaldehyde (MAA) protein adducts have been shown to initiate several pathological conditions in the lung. MDA-DNA adducts are pre-mutagenic in mammalian cells and induce frame shift and base-pair substitution mutations, whereas MAA protein adducts have been shown to induce inflammation and inhibit wound healing. This review provides an insight into different reactive aldehyde adducts and their role in the pathogenesis of lung disease.
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Affiliation(s)
- Muna Sapkota
- Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE 68198, USA.
| | - Todd A Wyatt
- Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Department of Internal Medicine, Division of Pulmonary, Critical Care, Sleep and Allergy, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- VA Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
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20
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Song BJ, Akbar M, Abdelmegeed MA, Byun K, Lee B, Yoon SK, Hardwick JP. Mitochondrial dysfunction and tissue injury by alcohol, high fat, nonalcoholic substances and pathological conditions through post-translational protein modifications. Redox Biol 2015; 3:109-23. [PMID: 25465468 PMCID: PMC4297931 DOI: 10.1016/j.redox.2014.10.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/21/2014] [Accepted: 10/23/2014] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are critically important in providing cellular energy ATP as well as their involvement in anti-oxidant defense, fat oxidation, intermediary metabolism and cell death processes. It is well-established that mitochondrial functions are suppressed when living cells or organisms are exposed to potentially toxic agents including alcohol, high fat diets, smoking and certain drugs or in many pathophysiological states through increased levels of oxidative/nitrative stress. Under elevated nitroxidative stress, cellular macromolecules proteins, DNA, and lipids can undergo different oxidative modifications, leading to disruption of their normal, sometimes critical, physiological functions. Recent reports also indicated that many mitochondrial proteins are modified via various post-translation modifications (PTMs) and primarily inactivated. Because of the recently-emerging information, in this review, we specifically focus on the mechanisms and roles of five major PTMs (namely oxidation, nitration, phosphorylation, acetylation, and adduct formation with lipid-peroxides, reactive metabolites, or advanced glycation end products) in experimental models of alcoholic and nonalcoholic fatty liver disease as well as acute hepatic injury caused by toxic compounds. We also highlight the role of the ethanol-inducible cytochrome P450-2E1 (CYP2E1) in some of these PTM changes. Finally, we discuss translational research opportunities with natural and/or synthetic anti-oxidants, which can prevent or delay the onset of mitochondrial dysfunction, fat accumulation and tissue injury. Hepatotoxic agents including alcohol and high fat elevate nitroxidative stress. Increased nitroxidative stress promotes post-translational protein modifications. Post-translational protein modifications of many proteins lead to their inactivation. Inactivation of mitochondrial proteins contributes to mitochondrial dysfunction. Mitochondrial dysfunction contributes to necrotic or apoptotic tissue injury.
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21
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Calamaras TD, Lee C, Lan F, Ido Y, Siwik DA, Colucci WS. The lipid peroxidation product 4-hydroxy-trans-2-nonenal causes protein synthesis in cardiac myocytes via activated mTORC1-p70S6K-RPS6 signaling. Free Radic Biol Med 2015; 82:137-46. [PMID: 25617592 PMCID: PMC4387097 DOI: 10.1016/j.freeradbiomed.2015.01.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 12/03/2014] [Accepted: 01/11/2015] [Indexed: 02/04/2023]
Abstract
Reactive oxygen species (ROS) are elevated in the heart in response to hemodynamic and metabolic stress and promote hypertrophic signaling. ROS also mediate the formation of lipid peroxidation-derived aldehydes that may promote myocardial hypertrophy. One lipid peroxidation by-product, 4-hydroxy-trans-2-nonenal (HNE), is a reactive aldehyde that covalently modifies proteins thereby altering their function. HNE adducts directly inhibit the activity of LKB1, a serine/threonine kinase involved in regulating cellular growth in part through its interaction with the AMP-activated protein kinase (AMPK), but whether this drives myocardial growth is unclear. We tested the hypothesis that HNE promotes myocardial protein synthesis and if this effect is associated with impaired LKB1-AMPK signaling. In adult rat ventricular cardiomyocytes, exposure to HNE (10 μM for 1h) caused HNE-LKB1 adduct formation and inhibited LKB1 activity. HNE inhibited the downstream kinase AMPK, increased hypertrophic mTOR-p70S6K-RPS6 signaling, and stimulated protein synthesis by 27.1 ± 3.5%. HNE also stimulated Erk1/2 signaling, which contributed to RPS6 activation but was not required for HNE-stimulated protein synthesis. HNE-stimulated RPS6 phosphorylation was completely blocked using the mTOR inhibitor rapamycin. To evaluate if LKB1 inhibition by itself could promote the hypertrophic signaling changes observed with HNE, LKB1 was depleted in adult rat ventricular myocytes using siRNA. LKB1 knockdown did not replicate the effect of HNE on hypertrophic signaling or affect HNE-stimulated RPS6 phosphorylation. Thus, in adult cardiac myocytes HNE stimulates protein synthesis by activation of mTORC1-p70S6K-RPS6 signaling most likely mediated by direct inhibition of AMPK. Because HNE in the myocardium is commonly increased by stimuli that cause pathologic hypertrophy, these findings suggest that therapies that prevent activation of mTORC1-p70S6K-RPS6 signaling may be of therapeutic value.
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Affiliation(s)
- Timothy D Calamaras
- Myocardial Biology Unit, Cardiovascular Medicine, and Diabetes and Metabolism Research Unit, Section of Endocrinology, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Charlie Lee
- Brigham and Women׳s Hospital, Boston, MA 02115, USA
| | - Fan Lan
- Department of Endocrinology, Second Affiliated Hospital Chongqing Medical University, Chongqing, China
| | - Yasuo Ido
- Diabetes and Metabolism Research Unit, Section of Endocrinology, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Deborah A Siwik
- Myocardial Biology Unit, Cardiovascular Medicine, and Diabetes and Metabolism Research Unit, Section of Endocrinology, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
| | - Wilson S Colucci
- Myocardial Biology Unit, Cardiovascular Medicine, and Diabetes and Metabolism Research Unit, Section of Endocrinology, Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA.
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Faulk DM, Wildemann JD, Badylak SF. Decellularization and cell seeding of whole liver biologic scaffolds composed of extracellular matrix. J Clin Exp Hepatol 2015; 5:69-80. [PMID: 25941434 PMCID: PMC4415199 DOI: 10.1016/j.jceh.2014.03.043] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/03/2014] [Indexed: 12/12/2022] Open
Abstract
The definitive treatment for patients with end-stage liver disease is orthotropic transplantation. However, this option is limited by the disparity between the number of patients needing transplantation and the number of available livers. This issue is becoming more severe as the population ages and as the number of new cases of end-stage liver failure increases. Patients fortunate enough to receive a transplant are required to receive immunosuppressive therapy and must live with the associated morbidity. Whole organ engineering of the liver may offer a solution to this liver donor shortfall. It has been shown that perfusion decellularization of a whole allogeneic or xenogeneic liver generates a three-dimensional ECM scaffold with intact macro and micro architecture of the native liver. A decellularized liver provides an ideal transplantable scaffold with all the necessary ultrastructure and signaling cues for cell attachment, differentiation, vascularization, and function. In this review, an overview of complementary strategies for creating functional liver grafts suitable for transplantation is provided. Early milestones have been met by combining stem and progenitor cells with increasingly complex scaffold materials and culture conditions.
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Key Words
- BAL, biohybrid artificial liver
- BMC, basement membrane complex
- CHAPS, 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate
- DAMP, damage associated molecular pattern
- ECM, extracellular matrix
- HMECs, human microvascular endothelial cells
- NPCs, non-parenchymal cells
- PLECM, porcine-liver-derived extracellular matrix
- SDS, sodium dodecyl sulfate
- SEC, sinusoidal endothelial cell
- SEM, scanning electron microscopy
- biologic scaffold
- decellularization
- extracellular matrix
- liver tissue engineering
- organ engineering
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Affiliation(s)
- Denver M. Faulk
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA,McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Justin D. Wildemann
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA
| | - Stephen F. Badylak
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15219, USA,McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15219, USA,Department of Surgery, University of Pittsburgh, Pittsburgh, PA 15213, USA,Address for correspondence: Stephen F. Badylak, 450 Technology Drive, Suite 300, University of Pittsburgh, Pittsburgh, PA 15219, USA. Tel.: +412 624 5252; fax: +412 624 5256.
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24
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Faulk DM, Johnson SA, Zhang L, Badylak SF. Role of the Extracellular Matrix in Whole Organ Engineering. J Cell Physiol 2014; 229:984-9. [DOI: 10.1002/jcp.24532] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 12/05/2013] [Indexed: 01/07/2023]
Affiliation(s)
- Denver M. Faulk
- McGowan Institute for Regenerative Medicine; University of Pittsburgh; Pittsburgh Pennsylvania
- Department of Bioengineering; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Scott A. Johnson
- McGowan Institute for Regenerative Medicine; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Li Zhang
- McGowan Institute for Regenerative Medicine; University of Pittsburgh; Pittsburgh Pennsylvania
| | - Stephen F. Badylak
- McGowan Institute for Regenerative Medicine; University of Pittsburgh; Pittsburgh Pennsylvania
- Department of Bioengineering; University of Pittsburgh; Pittsburgh Pennsylvania
- Department of Surgery; University of Pittsburgh; Pittsburgh Pennsylvania
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25
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Zheng R, Heck DE, Mishin V, Black AT, Shakarjian MP, Kong ANT, Laskin DL, Laskin JD. Modulation of keratinocyte expression of antioxidants by 4-hydroxynonenal, a lipid peroxidation end product. Toxicol Appl Pharmacol 2014; 275:113-21. [PMID: 24423726 DOI: 10.1016/j.taap.2014.01.001] [Citation(s) in RCA: 206] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 12/21/2013] [Accepted: 01/03/2014] [Indexed: 11/19/2022]
Abstract
4-Hydroxynonenal (4-HNE) is a lipid peroxidation end product generated in response to oxidative stress in the skin. Keratinocytes contain an array of antioxidant enzymes which protect against oxidative stress. In these studies, we characterized 4-HNE-induced changes in antioxidant expression in mouse keratinocytes. Treatment of primary mouse keratinocytes and PAM 212 keratinocytes with 4-HNE increased mRNA expression for heme oxygenase-1 (HO-1), catalase, NADPH:quinone oxidoreductase (NQO1) and glutathione S-transferase (GST) A1-2, GSTA3 and GSTA4. In both cell types, HO-1 was the most sensitive, increasing 86-98 fold within 6h. Further characterization of the effects of 4-HNE on HO-1 demonstrated concentration- and time-dependent increases in mRNA and protein expression which were maximum after 6h with 30 μM. 4-HNE stimulated keratinocyte Erk1/2, JNK and p38 MAP kinases, as well as PI3 kinase. Inhibition of these enzymes suppressed 4-HNE-induced HO-1 mRNA and protein expression. 4-HNE also activated Nrf2 by inducing its translocation to the nucleus. 4-HNE was markedly less effective in inducing HO-1 mRNA and protein in keratinocytes from Nrf2-/- mice, when compared to wild type mice, indicating that Nrf2 also regulates 4-HNE-induced signaling. Western blot analysis of caveolar membrane fractions isolated by sucrose density centrifugation demonstrated that 4-HNE-induced HO-1 is localized in keratinocyte caveolae. Treatment of the cells with methyl-β-cyclodextrin, which disrupts caveolar structure, suppressed 4-HNE-induced HO-1. These findings indicate that 4-HNE modulates expression of antioxidant enzymes in keratinocytes, and that this can occur by different mechanisms. Changes in expression of keratinocyte antioxidants may be important in protecting the skin from oxidative stress.
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Affiliation(s)
- Ruijin Zheng
- Pharmacology and Toxicology and Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | - Diane E Heck
- Environmental Health Science, New York Medical College, Valhalla, NY, USA
| | - Vladimir Mishin
- Pharmacology and Toxicology and Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | - Adrienne T Black
- Pharmacology and Toxicology and Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | | | - Ah-Ng Tony Kong
- Pharmacology and Toxicology and Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | - Debra L Laskin
- Pharmacology and Toxicology and Pharmaceutics, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | - Jeffrey D Laskin
- Environmental and Occupational Medicine, Rutgers University-Robert Wood Johnson Medical School, Piscataway, NJ, USA.
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26
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Ding X, Beier JI, Baldauf KJ, Jokinen JD, Zhong H, Arteel GE. Acute ethanol preexposure promotes liver regeneration after partial hepatectomy in mice by activating ALDH2. Am J Physiol Gastrointest Liver Physiol 2014; 306:G37-47. [PMID: 24177029 PMCID: PMC3920082 DOI: 10.1152/ajpgi.00085.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
It is known that chronic ethanol significantly impairs liver regeneration. However, the effect of acute ethanol exposure on liver regeneration remains largely unknown. To address this question, C57Bl6/J mice were exposed to acute ethanol (6 g/kg intragastrically) for 3 days, and partial hepatectomy (PHx) was performed 24 h after the last dose. Surprisingly, acute ethanol preexposure promoted liver regeneration. This effect of ethanol did not correlate with changes in expression of cell cycle regulatory genes (e.g., cyclin D1, p21, and p27) but did correlate with protection against the effect of PHx on indices of impaired lipid and carbohydrate metabolism. Ethanol preexposure protected against inhibition of the oxidant-sensitive mitochondrial enzyme, aconitase. The activity of aldehyde dehydrogenase 2 (ALDH2) was significantly increased by ethanol preexposure. The effect of ethanol was blocked by inhibiting (Daidzin) and was mimicked by activating (Alda-1) ALDH2. Lipid peroxides are also substrates for ALDH2; indeed, alcohol preexposure blunted the increase in lipid peroxidation (4OH-nonenal adducts) caused by PHx. Taken together, these data suggest that acute preoperative ethanol exposure "preconditions" the liver to respond more rapidly to regenerate after PHx by activating mitochondrial ALDH2, which prevents oxidative stress in this compartment.
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Affiliation(s)
- Xiang Ding
- Dept. of Pharmacology and Toxicology, 505 S Hancock St., CTRB, Rm 506, Univ. of Louisville Health Sciences Center, Louisville, KY, 40292.
| | - Juliane I. Beier
- 1Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville; ,2University of Louisville Alcohol Research Center, Louisville, Kentucky
| | - Keegan J. Baldauf
- 1Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville; ,2University of Louisville Alcohol Research Center, Louisville, Kentucky
| | - Jenny D. Jokinen
- 1Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville; ,2University of Louisville Alcohol Research Center, Louisville, Kentucky
| | - Hai Zhong
- 1Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville; ,2University of Louisville Alcohol Research Center, Louisville, Kentucky
| | - Gavin E. Arteel
- 1Department of Pharmacology and Toxicology, University of Louisville Health Sciences Center, Louisville; ,2University of Louisville Alcohol Research Center, Louisville, Kentucky
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Shearn CT, Smathers RL, Backos DS, Reigan P, Orlicky DJ, Petersen DR. Increased carbonylation of the lipid phosphatase PTEN contributes to Akt2 activation in a murine model of early alcohol-induced steatosis. Free Radic Biol Med 2013; 65:680-692. [PMID: 23872024 PMCID: PMC3859727 DOI: 10.1016/j.freeradbiomed.2013.07.011] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 06/25/2013] [Accepted: 07/04/2013] [Indexed: 10/26/2022]
Abstract
The production of reactive aldehydes such as 4-hydroxynonenal (4-HNE) is a key event in the pathogenesis of alcoholic liver disease (ALD), which ranges from simple steatosis to fibrosis. The lipid phosphatase PTEN plays a central role in the regulation of lipid metabolism in the liver. In this study, the effects of chronic ethanol feeding and carbonylation on the PTEN signaling pathway were examined in a 9-week mouse feeding model for ALD. Chronic ethanol consumption resulted in altered redox homeostasis as evidenced by decreased GSH, decreased Trx1, and increased GST activity. Both PTEN expression and PTEN phosphorylation were significantly increased in the livers of ethanol-fed mice. Carbonylation of PTEN increased significantly in the ethanol-fed mice compared to pair-fed control animals, corresponding to decreased PTEN 3-phosphatase activity. Concomitantly, increased expression of Akt2 along with increased Akt phosphorylation at residues Thr(308), Thr(450), and Ser(473) was observed resulting in increased Akt2 activity in the ethanol-fed animals. Akt2 activation corresponded to a decrease in cytosolic SREBP and ChREBP. Subsequent LC/MS/MS analysis of 4-HNE-modified recombinant human PTEN identified Michael addition adducts of 4-HNE on Cys(71), Cys(136), Lys(147), Lys(223), Cys(250), Lys(254), Lys(313), Lys(327), and Lys(344). Computational-based molecular modeling analysis of 4-HNE adducted to Cys(71) near the active site and Lys(327) in the C2 domain of PTEN suggested inhibition of enzyme catalysis via either stearic hindrance of the active-site pocket or prevention of C2 domain-dependent PTEN function. We hypothesize that 4-HNE-mediated PTEN inhibition contributes to the observed activation of Akt2, suggesting a possible novel mechanism of lipid accumulation in response to increased reactive aldehyde production during chronic ethanol administration in mice.
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Affiliation(s)
- C T Shearn
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado at Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - R L Smathers
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado at Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - D S Backos
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado at Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - P Reigan
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado at Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - D J Orlicky
- Department of Pathology, School of Medicine, University of Colorado at Denver, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Dennis R Petersen
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado at Denver, Anschutz Medical Campus, Aurora, CO 80045, USA.
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28
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McElhanon KE, Bose C, Sharma R, Wu L, Awasthi YC, Singh SP. Gsta4 Null Mouse Embryonic Fibroblasts Exhibit Enhanced Sensitivity to Oxidants: Role of 4-Hydroxynonenal in Oxidant Toxicity. ACTA ACUST UNITED AC 2013; 2. [PMID: 24353929 DOI: 10.4236/ojapo.2013.21001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The alpha class glutathione s-transferase (GST) isozyme GSTA4-4 (EC2.5.1.18) exhibits high catalytic efficiency to-wards 4-hydroxynon-2-enal (4-HNE), a major end product of oxidative stress induced lipid peroxidation. Exposure of cells and tissues to heat, radiation, and chemicals has been shown to induce oxidative stress resulting in elevated concentrations of 4-HNE that can be detrimental to cell survival. Alternatively, at physiological levels 4-HNE acts as a signaling molecule conveying the occurrence of oxidative events initiating the activation of adaptive pathways. To examine the impact of oxidative/electrophilic stress in a model with impaired 4-HNE metabolizing capability, we disrupted the Gsta4 gene that encodes GSTA4-4 in mice. The effect of electrophile and oxidants on embryonic fibroblasts (MEF) isolated from wild type (WT) and Gsta4 null mice were examined. Results indicate that in the absence of GSTA4-4, oxidant-induced toxicity is potentiated and correlates with elevated accumulation of 4-HNE adducts and DNA damage. Treatment of Gsta4 null MEF with 1,1,4-tris(acetyloxy)-2(E)-nonene [4-HNE(Ac)3], a pro-drug form of 4-HNE, resulted in the activation and phosphorylation of the c-jun-N-terminal kinase (JNK), extracellular-signal-regulated kinases (ERK 1/2) and p38 mitogen activated protein kinases (p38 MAPK) accompanied by enhanced cleavage of caspase-3. Interestingly, when recombinant mammalian or invertebrate GSTs were delivered to Gsta4 null MEF, activation of stress-related kinases in 4-HNE(Ac)3 treated Gsta4 null MEF were inversely correlated with the catalytic efficiency of delivered GSTs towards 4-HNE. Our data suggest that GSTA4-4 plays a major role in protecting cells from the toxic effects of oxidant chemicals by attenuating the accumulation of 4-HNE.
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Affiliation(s)
- Kevin E McElhanon
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA ; Central Arkansas Veterans Healthcare System, Little Rock, USA
| | - Chhanda Bose
- Central Arkansas Veterans Healthcare System, Little Rock, USA ; Department of Internal Medicine, Nephrology Division, University of Arkansas for Medical Sciences, Little Rock, USA
| | - Rajendra Sharma
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA ; Central Arkansas Veterans Healthcare System, Little Rock, USA
| | - Liping Wu
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA ; Central Arkansas Veterans Healthcare System, Little Rock, USA
| | - Yogesh C Awasthi
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, USA
| | - Sharda P Singh
- Department of Pharmacology and Toxicology, University of Arkansas for Medical Sciences, Little Rock, USA ; Central Arkansas Veterans Healthcare System, Little Rock, USA
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Smathers RL, Fritz KS, Galligan JJ, Shearn CT, Reigan P, Marks MJ, Petersen DR. Characterization of 4-HNE modified L-FABP reveals alterations in structural and functional dynamics. PLoS One 2012; 7:e38459. [PMID: 22701647 PMCID: PMC3368874 DOI: 10.1371/journal.pone.0038459] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 05/05/2012] [Indexed: 01/01/2023] Open
Abstract
4-Hydroxynonenal (4-HNE) is a reactive α,β-unsaturated aldehyde produced during oxidative stress and subsequent lipid peroxidation of polyunsaturated fatty acids. The reactivity of 4-HNE towards DNA and nucleophilic amino acids has been well established. In this report, using proteomic approaches, liver fatty acid-binding protein (L-FABP) is identified as a target for modification by 4-HNE. This lipid binding protein mediates the uptake and trafficking of hydrophobic ligands throughout cellular compartments. Ethanol caused a significant decrease in L-FABP protein (P<0.001) and mRNA (P<0.05), as well as increased poly-ubiquitinated L-FABP (P<0.001). Sites of 4-HNE adduction on mouse recombinant L-FABP were mapped using MALDI-TOF/TOF mass spectrometry on apo (Lys57 and Cys69) and holo (Lys6, Lys31, His43, Lys46, Lys57 and Cys69) L-FABP. The impact of 4-HNE adduction was found to occur in a concentration-dependent manner; affinity for the fluorescent ligand, anilinonaphthalene-8-sulfonic acid, was reduced from 0.347 µM to Kd(1) = 0.395 µM and Kd(2) = 34.20 µM. Saturation analyses revealed that capacity for ligand is reduced by approximately 50% when adducted by 4-HNE. Thermal stability curves of apo L-FABP was also found to be significantly affected by 4-HNE adduction (ΔTm = 5.44°C, P<0.01). Computational-based molecular modeling simulations of adducted protein revealed minor conformational changes in global protein structure of apo and holo L-FABP while more apparent differences were observed within the internal binding pocket, revealing reduced area and structural integrity. New solvent accessible portals on the periphery of the protein were observed following 4-HNE modification in both the apo and holo state, suggesting an adaptive response to carbonylation. The results from this study detail the dynamic process associated with L-FABP modification by 4-HNE and provide insight as to how alterations in structural integrity and ligand binding may a contributing factor in the pathogenesis of ALD.
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Affiliation(s)
- Rebecca L. Smathers
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Kristofer S. Fritz
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - James J. Galligan
- Department of Pharmacology, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Colin T. Shearn
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Philip Reigan
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Michael J. Marks
- Institute for Behavioral Genetics, University of Colorado, Boulder, Colorado, United States of America
| | - Dennis R. Petersen
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
- * E-mail:
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Galligan JJ, Smathers RL, Fritz KS, Epperson LE, Hunter LE, Petersen DR. Protein carbonylation in a murine model for early alcoholic liver disease. Chem Res Toxicol 2012; 25:1012-21. [PMID: 22502949 DOI: 10.1021/tx300002q] [Citation(s) in RCA: 242] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hepatic oxidative stress and subsequent lipid peroxidation are well-recognized consequences of sustained ethanol consumption. The covalent adduction of nucleophilic amino acid side-chains by lipid electrophiles is significantly increased in patients with alcoholic liver disease (ALD); a global assessment of in vivo protein targets and the consequences of these modifications, however, has not been conducted. In this article, we describe the identification of novel protein targets for covalent adduction in a 6-week murine model for ALD. Ethanol-fed mice displayed a 2-fold increase in hepatic TBARS, while immunohistochemical analysis for the reactive aldehydes 4-hydroxynonenal (4-HNE), 4-oxononenal (4-ONE), acrolein (ACR), and malondialdehyde (MDA) revealed a marked increase in the staining of modified proteins in the ethanol-treated mice. Increased protein carbonyl content was confirmed utilizing subcellular fractionation of liver homogenates followed by biotin-tagging through hydrazide chemistry, where approximately a 2-fold increase in modified proteins was observed in microsomal and cytosolic fractions. To determine targets of protein carbonylation, a secondary hydrazide method coupled to a highly sensitive 2-dimensional liquid chromatography tandem mass spectrometry (2D LC-MS/MS or MuDPIT) technique was utilized. Our results have identified 414 protein targets for modification by reactive aldehydes in ALD. The presence of novel in vivo sites of protein modification by 4-HNE (2), 4-ONE (4) and ACR (2) was also confirmed in our data set. While the precise impact of protein carbonylation in ALD remains unknown, a bioinformatic analysis of the data set has revealed key pathways associated with disease progression, including fatty acid metabolism, drug metabolism, oxidative phosphorylation, and the TCA cycle. These data suggest a major role for aldehyde adduction in the pathogenesis of ALD.
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Affiliation(s)
- James J Galligan
- Department of Pharmacology, School of Medicine, University of Colorado-Denver, Aurora, CO 80045, USA
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Fritz KS, Petersen DR. Exploring the biology of lipid peroxidation-derived protein carbonylation. Chem Res Toxicol 2011; 24:1411-9. [PMID: 21812433 DOI: 10.1021/tx200169n] [Citation(s) in RCA: 279] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The sustained overproduction of reactive oxygen and nitrogen species results in an imbalance of cellular prooxidant-antioxidant systems and is implicated in numerous disease states, including alcoholic liver disease, cancer, neurological disorders, inflammation, and cardiovascular disease. The accumulation of reactive aldehydes resulting from sustained oxidative stress and lipid peroxidation is an underlying factor in the development of these pathologies. Determining the biochemical factors that elicit cellular responses resulting from protein carbonylation remains a key element to developing therapeutic approaches and ameliorating disease pathologies. This review details our current understanding of the generation of reactive aldehydes via lipid peroxidation resulting in protein carbonylation, focusing on pathophysiologic factors associated with 4-hydroxynonenal-protein modification. Additionally, an overview of in vitro and in vivo model systems used to study the physiologic impact of protein carbonylation is presented. Finally, an update of the methods commonly used in characterizing protein modification by reactive aldehydes provides an overview of isolation techniques, mass spectrometry, and computational biology. It is apparent that research in this area employing state-of-the-art proteomics, mass spectrometry, and computational biology is rapidly evolving, yielding foundational knowledge concerning the molecular mechanisms of protein carbonylation and its relation to a spectrum of diseases associated with oxidative stress.
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Affiliation(s)
- Kristofer S Fritz
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado 80045, USA
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Begriche K, Massart J, Robin MA, Borgne-Sanchez A, Fromenty B. Drug-induced toxicity on mitochondria and lipid metabolism: mechanistic diversity and deleterious consequences for the liver. J Hepatol 2011; 54:773-94. [PMID: 21145849 DOI: 10.1016/j.jhep.2010.11.006] [Citation(s) in RCA: 349] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Revised: 11/05/2010] [Accepted: 11/09/2010] [Indexed: 02/08/2023]
Abstract
Numerous investigations have shown that mitochondrial dysfunction is a major mechanism of drug-induced liver injury, which involves the parent drug or a reactive metabolite generated through cytochromes P450. Depending of their nature and their severity, the mitochondrial alterations are able to induce mild to fulminant hepatic cytolysis and steatosis (lipid accumulation), which can have different clinical and pathological features. Microvesicular steatosis, a potentially severe liver lesion usually associated with liver failure and profound hypoglycemia, is due to a major inhibition of mitochondrial fatty acid oxidation (FAO). Macrovacuolar steatosis, a relatively benign liver lesion in the short term, can be induced not only by a moderate reduction of mitochondrial FAO but also by an increased hepatic de novo lipid synthesis and a decreased secretion of VLDL-associated triglycerides. Moreover, recent investigations suggest that some drugs could favor lipid deposition in the liver through primary alterations of white adipose tissue (WAT) homeostasis. If the treatment is not interrupted, steatosis can evolve toward steatohepatitis, which is characterized not only by lipid accumulation but also by necroinflammation and fibrosis. Although the mechanisms involved in this aggravation are not fully characterized, it appears that overproduction of reactive oxygen species by the damaged mitochondria could play a salient role. Numerous factors could favor drug-induced mitochondrial and metabolic toxicity, such as the structure of the parent molecule, genetic predispositions (in particular those involving mitochondrial enzymes), alcohol intoxication, hepatitis virus C infection, and obesity. In obese and diabetic patients, some drugs may induce acute liver injury more frequently while others may worsen the pre-existent steatosis (or steatohepatitis).
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Affiliation(s)
- Karima Begriche
- Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA
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33
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Galligan JJ, Fritz KS, Tipney H, Smathers RL, Roede JR, Shearn CT, Hunter LE, Petersen DR. Profiling impaired hepatic endoplasmic reticulum glycosylation as a consequence of ethanol ingestion. J Proteome Res 2011; 10:1837-47. [PMID: 21319786 DOI: 10.1021/pr101101s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Alcoholic liver disease (ALD) is a prominent cause of morbidity and mortality in the United States. Alterations in protein folding occur in numerous disease states, including ALD. The endoplasmic reticulum (ER) is the primary site of post-translational modifications (PTM) within the cell. Glycosylation, the most abundant PTM, affects protein stability, structure, localization, and activity. Decreases in hepatic glycosylation machinery have been observed in rodent models of ALD, but specific protein targets have not been identified. Utilizing two-dimensional gel electrophoresis and liquid chromatography-tandem mass spectrometry, glycoproteins were identified in hepatic microsomal fractions from control and ethanol-fed mice. This study reports for the first time a global decrease in ER glycosylation. Additionally, the identification of 30 glycoproteins within this fraction elucidates pathway-specific alterations in ALD impaired glycosylation. Among the identified proteins, triacylglycerol hydrolase (TGH) is positively affected by glycosylation, showing increased activity following the addition of sugar moieties. Impaired TGH activity is associated with increased cellular storage of lipids and provides a potential mechanism for the observed pathologies associated with ALD.
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Affiliation(s)
- James J Galligan
- Department of Pharmacology, University of Colorado Denver, Aurora, Colorado 80045, United States
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Overview of lipid peroxidation products and hepatic protein modification in alcoholic liver disease. Chem Biol Interact 2011; 192:107-12. [PMID: 21354120 DOI: 10.1016/j.cbi.2011.02.021] [Citation(s) in RCA: 299] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 02/17/2011] [Accepted: 02/18/2011] [Indexed: 11/23/2022]
Abstract
OBJECTIVES Oxidative stress is one component of alcoholic liver disease (ALD) that is manifested in the peroxidation of cellular lipids producing the electrophile, 4-hydroxynonenal (4-HNE). This electrophile is proposed to modify essential cellular proteins resulting in loss of protein function and cellular homeostasis. Studies were initiated to identify hepatic proteins that are targets of 4-HNE modification and determine their relationship with progression of the early stages of ALD. METHODS Rat and mouse models were developed using the Lieber-DeCarli diet to simulate early stages of ALD consisting of fatty liver (steatosis) and hepatocellular injury indicated by a 1.5-2-fold elevation of plasma ALT activity. Liver samples obtained from control and ethanol treated animals were subjected to two-dimensional electrophoresis and immunoblotting using polyclonal antibodies generated against 4-HNE epitopes for detection of proteins modified by 4-HNE. Following identification of 4-HNE adducted proteins, the respective recombinant proteins modified with physiologic concentrations of 4-HNE were evaluated to determine the functional consequences of 4-HNE modification. RESULTS One group of proteins identified included Hsp70, Hsp90 and protein disulfide isomerase (PDI), all of which are involved in protein folding or processing are targets of adduction. In vitro assays indicated significant impairment of the protein activities following modification with physiologically relevant concentrations of 4-HNE. Liver fatty acid binding protein, L-FABP, was also identified as a target and additional studies revealed that the levels of this protein were significantly decreased because of chronic ethanol ingestion. Erk1/2 was identified as a target for modification and subsequently determined to have impaired activity. CONCLUSIONS Inhibition of Hsp70, Hsp90 and PDI function could be involved in initiation of the early phases of ER stress contributing to stimulation and accumulation of hepatic lipids. Likewise, impairment of L-FABP activity could also disrupt lipid transport also contributing to steatosis. The modification and inhibition of Erk1/2 by 4-HNE may also contribute to the decreased hepatocellular proliferation associated with ALD. Collectively, these results provide new information concerning the mechanisms whereby the modification of hepatic proteins by 4-HNE contributes to ALD.
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35
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Makia NL, Bojang P, Falkner KC, Conklin DJ, Prough RA. Murine hepatic aldehyde dehydrogenase 1a1 is a major contributor to oxidation of aldehydes formed by lipid peroxidation. Chem Biol Interact 2011; 191:278-87. [PMID: 21256123 DOI: 10.1016/j.cbi.2011.01.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 01/11/2011] [Accepted: 01/12/2011] [Indexed: 01/25/2023]
Abstract
Reactive lipid aldehydes are implicated in the pathogenesis of various oxidative stress-mediated diseases, including non-alcoholic steatohepatitis, atherosclerosis, Alzheimer's and cataract. In the present study, we sought to define which hepatic Aldh isoform plays a major role in detoxification of lipid-derived aldehydes, such as acrolein and HNE by enzyme kinetic and gene expression studies. The catalytic efficiencies for metabolism of acrolein by Aldh1a1 was comparable to that of Aldh3a1 (V(max)/K(m)=23). However, Aldh1a1 exhibits far higher affinity for acrolein (K(m)=23.2 μM) compared to Aldh3a1 (K(m)=464 μM). Aldh1a1 displays a 3-fold higher catalytic efficiency for HNE than Aldh3a1 (218 ml/min/mg vs 69 ml/min/mg). The endogenous Aldh1a1 gene was highly expressed in mouse liver and a liver-derived cell line (Hepa-1c1c7) compared to Aldh2, Aldh1b1 and Aldh3a1. Aldh1a1 mRNA levels was 34-fold and 73-fold higher than Aldh2 in mouse liver and Hepa-1c1c7 cells respectively. Aldh3a1 gene was absent in mouse liver, but moderately expressed in Hepa-1c1c7 cells compared to Aldh1a1. We demonstrated that knockdown of Aldh1a1 expression by siRNA caused Hepa-1c1c7 cells to be more sensitive to acrolein-induced cell death and resulted in increased accumulation of acrolein-protein adducts and caspase 3 activation. These results indicate that Aldh1a1 plays a major role in cellular defense against oxidative damage induced by reactive lipid aldehydes in mouse liver. We also noted that hepatic Aldh1a1 mRNA levels were significantly increased (≈3-fold) in acrolein-fed mice compared to control. In addition, hepatic cytosolic ALDH activity was induced by acrolein when 1mM NAD(+) was used as cofactor, suggesting an Aldh1a1-protective mechanism against acrolein toxicity in mice liver. Thus, mechanisms to induce Aldh1a1 gene expression may provide a useful rationale for therapeutic protection against oxidative stress-induced pathologies.
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Affiliation(s)
- Ngome L Makia
- Department of Biochemistry & Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40292, United States
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Wang Z, Yao T, Song Z. Extracellular signal-regulated kinases 1/2 suppression aggravates transforming growth factor-beta1 hepatotoxicity: a potential mechanism for liver injury in methionine-choline deficient-diet-fed mice. Exp Biol Med (Maywood) 2010; 235:1347-55. [PMID: 20962016 DOI: 10.1258/ebm.2010.010160] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Hepatocyte cell death is a characteristic indication in the development of non-alcoholic steatohepatitis (NASH); however, the underlying mechanism is still unclear. In this study, we examined the potential mechanism(s) involved in the development of liver injury using a methionine-choline deficient (MCD) diet feeding NASH model. Male C57BL6/J mice were fed MCD and methionine-choline sufficient (MCS) diet for two weeks before being killed. Our results showed that MCD diet feeding resulted in fatty liver and liver injury, evidenced by increased hepatic triglyceride (TG), plasma alanine aminotransferases and hepatic thiobarbituric acid reactive substances levels in MCD-fed mice. Furthermore, we found that MCD diet feeding caused remarkable suppression of hepatic extracellular signal-regulated kinases (ERK) 1/2 activation and increased transforming growth factor (TGF)-beta1 levels in plasma and the liver tissue. In vitro investigations showed that intracellular MEK/ERK1/2 activation status played a critical role in the determination of sensitivity of hepatocytes to TGF-beta1-induced cell death. HepG2 cells, otherwise resistant to TGF-beta1 killing due to high level of ERK1/2 activation, was sensitized by U0126, a specific MEK/ERK1/2 inhibitor, to TGF-beta1 cytotoxicity. H4IIEC3 cells, which have lower level of constitutive ERK1/2 activity, are sensitive to TGF-beta1-induced cell death. Lastly, we demonstrated that administration of epidermal growth factor, a strong ERK1/2 activator, to MCD-fed mice attenuated liver injury without affecting hepatic TG accumulation. Our findings demonstrated that hepatic ERK1/2 inactivation aggravates TGF-beta1-induced hepatotoxicity, which may contribute, at least in part, to the initiation of liver injury in NASH.
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Affiliation(s)
- Zhigang Wang
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL 60612, USA
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Wang Z, Yao T, Song Z. Involvement and mechanism of DGAT2 upregulation in the pathogenesis of alcoholic fatty liver disease. J Lipid Res 2010; 51:3158-65. [PMID: 20739640 DOI: 10.1194/jlr.m007948] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mechanisms involved in the development of alcoholic liver disease (ALD) are not well established. We investigated the involvement of acyl-CoA: diacylglycerol acyltransferase 2 (DGAT2) upregulation in mediating hepatic fat accumulation induced by chronic alcohol consumption. Chronic alcohol feeding caused fatty liver and increased hepatic DGAT2 gene and protein expression, concomitant with a significant suppression of hepatic MAPK/ERK kinase/extracellular regulated kinase 1/2 (MEK/ERK1/2) activation. In vitro studies demonstrated that specific inhibitors of the MEK/ERK1/2 pathway increased DGAT2 gene expression and triglyceride (TG) contents in HepG2 cells, whereas epidermal growth factor, a strong ERK1/2 activator, had the opposite effect. Moreover, chronic alcohol feeding decreased hepatic S-adenosylmethionine (SAM): S-adenosylhomocysteine (SAH) ratio, an indicator of disrupted transmethylation reactions. Mechanistic investigations revealed that N-acetyl-S-farnesyl-L-cysteine, a potent inhibitor of isoprenylcysteine carboxyl methyltransferase, suppressed ERK1/2 activation, followed by an enhanced DGAT2 expression and an elevated TG content in HepG2 cells. Lastly, we demonstrated that the beneficial effects of betaine supplementation in ALD were associated with improved SAM/SAH ratio, alleviated ERK1/2 inhibition, and attenuated DGAT2 upregulation. In conclusion, our data suggest that upregulation of DGAT2 plays an important role in the pathogenesis of ALD, and that abnormal methionine metabolism contributes, at least partially, to DGAT2 upregulation via suppression of MEK/ERK1/2 activation.
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Affiliation(s)
- Zhigang Wang
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL 60612, USA
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Chaudhary P, Sharma R, Sharma A, Vatsyayan R, Yadav S, Singhal SS, Rauniyar N, Prokai L, Awasthi S, Awasthi YC. Mechanisms of 4-hydroxy-2-nonenal induced pro- and anti-apoptotic signaling. Biochemistry 2010; 49:6263-75. [PMID: 20565132 DOI: 10.1021/bi100517x] [Citation(s) in RCA: 272] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In recent years, 4-hydroxy-2-nonenal (4-HNE) has emerged as an important second messenger in cell cycle signaling. Here, we demonstrate that 4-HNE induces signaling for apoptosis via both the Fas-mediated extrinsic and the p53-mediated intrinsic pathways in HepG2 cells. 4-HNE induces a Fas-mediated DISC independent apoptosis pathway by activating ASK1, JNK, and caspase-3. Parallel treatment of 4-HNE to HepG2 cells also induces apoptosis by the p53 pathway through activation of Bax, p21, JNK, and caspase-3. Exposure of HepG2 cells to 4-HNE leads to the activation of both Fas and Daxx, promotes the export of Daxx from the nucleus to cytoplasm, and facilitates Fas-Daxx binding. Depletion of Daxx by siRNA results in the potentiation of apoptosis, indicating that Fas-Daxx binding in fact is inhibitory to Fas-mediated apoptosis in cells. 4-HNE-induced translocation of Daxx is also accompanied by the activation and nuclear accumulation of HSF1 and up-regulation of heat shock protein Hsp70. All these effects of 4-HNE in cells can be attenuated by ectopic expression of hGSTA4-4, the isozyme of glutathione S-transferase with high activity for 4-HNE. Through immunoprecipitation and liquid chromatography-tandem mass spectrometry, we have demonstrated the covalent binding of 4-HNE to Daxx. We also demonstrate that 4-HNE modification induces phosphorylation of Daxx at Ser668 and Ser671 to facilitate its cytoplasmic export. These results indicate that while 4-HNE exhibits toxicity through several mechanisms, in parallel it evokes signaling for defense mechanisms to self-regulate its toxicity and can simultaneously affect multiple signaling pathways through its interactions with membrane receptors and transcription factors/repressors.
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Affiliation(s)
- Pankaj Chaudhary
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA
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Roede JR, Orlicky DJ, Fisher AB, Petersen DR. Overexpression of peroxiredoxin 6 does not prevent ethanol-mediated oxidative stress and may play a role in hepatic lipid accumulation. J Pharmacol Exp Ther 2009; 330:79-88. [PMID: 19386791 DOI: 10.1124/jpet.109.152983] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Oxidative stress is implicated in the etiology of many diseases, including alcoholic liver disease (ALD). Peroxiredoxin 6 is a cytosolic peroxidase that has been demonstrated to protect various tissues, such as skin, lung, and cardiac muscle, against acute oxidative insults. Consequently, peroxiredoxin 6 was hypothesized to also protect the liver from oxidative stress generated during the process of chronic ethanol ingestion. To test this, wild-type peroxiredoxin 6 knockout mice (KO), and transgenic peroxiredoxin 6 overexpressing mice (TG) were fed an ethanol-containing diet. Various biomarkers of ALD were assessed, along with the effects of chronic ethanol consumption on the antioxidant defenses. After 9 weeks of ethanol consumption, all backgrounds exhibited elevations of plasma alanine aminotransferase activity, hepatosteatosis, CYP2E1 induction, and lipid peroxidation; however, hepatic triglyceride accumulation seemed to be exacerbated in ethanol-fed TG mice. Differences in antioxidant protein expression and activity in response to chronic ethanol consumption were also observed. Examples include significant inductions of catalase and glutathione transferase activity in ethanol-fed KO and TG mice, along with elevated levels of glutathione peroxidase activity. These alterations in antioxidant defenses could be attributed to either compensatory responses due to the genetic manipulations or ethanol-mediated responses. In conclusion, both ethanol-fed KO and ethanol-fed TG mice developed early stage ALD and peroxiredoxin 6 may play a role in ethanol-mediated hepatic lipid accumulation.
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Affiliation(s)
- James R Roede
- Department of Pharmaceutical Sciences, University of Colorado, Denver, Colorado, USA
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Scaloni A, Codarin E, Di Maso V, Arena S, Renzone G, Tiribelli C, Quadrifoglio F, Tell G. Modern strategies to identify new molecular targets for the treatment of liver diseases: The promising role of Proteomics and Redox Proteomics investigations. Proteomics Clin Appl 2009; 3:242-62. [DOI: 10.1002/prca.200800169] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Indexed: 12/16/2022]
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Abstract
Alcoholic liver disease still represents an important cause for death and disability in most well-developed countries and is becoming a leading cause of disease in developing countries. It is now increasingly clear that, besides the formation of acetaldehyde, alcohol effects on the liver include oxidative stress, disturbances in methionine metabolism, endoplasmic reticulum stress, inflammatory/immune responses and adipokine imbalances. This article will discuss the most recent findings on the mechanisms by which alcohol abuse causes hepatic steatosis and steatohepatitis, and now it contributes to the progression of fibrosis. Although still incomplete, these data shed new light on the multifactorial pathogenesis of alcoholic liver disease and open new possibilities in the understanding of how gender and genetic factors can influence disease progression.
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Affiliation(s)
- Emanuele Albano
- Department of Medical Science, University Amedeo Avogadro of East Piedmont, Via Solaroli 17, 28100 Novara, Italy.
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Roede JR, Stewart BJ, Petersen DR. Decreased expression of peroxiredoxin 6 in a mouse model of ethanol consumption. Free Radic Biol Med 2008; 45:1551-8. [PMID: 18852041 DOI: 10.1016/j.freeradbiomed.2008.08.032] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 08/22/2008] [Accepted: 08/31/2008] [Indexed: 12/14/2022]
Abstract
Alcoholic liver disease is multifactorial and oxidative stress is believed to play an intimate role in the initiation and progression of this pathology. The goals of this study were to investigate the effect of chronic ethanol treatment on inducing hepatic oxidative stress and peroxiredoxin 6 expression. After 9 weeks of treatment with an ethanol-containing diet, significant increases in serum ALT activity, liver to body weight ratio, liver triglycerides, CYP2E1 protein expression, and CYP2E1 activity were observed. Chronic ethanol feeding resulted in oxidative stress as evidenced by decreases in hepatic glutathione content and increased deposition of 4-hydroxynonenal and 4-oxononenal protein adducts. In addition, novel findings of decreased PRX6 protein and mRNA and increased levels of carbonylated PRX6 protein were observed in the ethanol-treated animals compared to the pair-fed controls. Lastly, NF-kappaB activity was found to be significantly increased in the ethanol-treated animals. Concurrent with the increase in NF-kappaB activity, decreases in both MEK1/2 and ERK1/2 phosphorylation were also observed in the ethanol-treated animals compared to the pair-fed controls. Together, these data demonstrate that chronic ethanol treatment results in oxidative stress, implicating NF-kappaB activation as an integral mechanism in the negative regulation of PRX6 gene expression in the mouse liver.
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Affiliation(s)
- James R Roede
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Colorado Health Sciences Center, Denver, CO 80262, USA
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Abstract
Alcoholic fatty liver is a potentially pathologic condition which can progress to steatohepatitis, fibrosis, and cirrhosis if alcohol consumption is continued. Alcohol exposure may induce fatty liver by increasing NADH/NAD(+) ratio, increasing sterol regulatory element-binding protein-1 (SREBP-1) activity, decreasing peroxisome proliferator-activated receptor-alpha (PPAR-alpha) activity, and increasing complement C3 hepatic levels. Alcohol may increase SREBP-1 activity by decreasing the activities of AMP-activated protein kinase and sirtuin-1. Tumor necrosis factor-alpha (TNF-alpha) produced in response to alcohol exposure may cause fatty liver by up-regulating SREBP-1 activity, whereas betaine and pioglitazone may attenuate fatty liver by down-regulating SREBP-1 activity. PPAR-alpha agonists have potentials to attenuate alcoholic fatty liver. Adiponectin and interleukin-6 may attenuate alcoholic fatty liver by up-regulating PPAR-alpha and insulin signaling pathways while down-regulating SREBP-1 activity and suppressing TNF-alpha production. Recent studies show that paracrine activation of hepatic cannabinoid receptor 1 by hepatic stellate cell-derived endocannabinoids also contributes to the development of alcoholic fatty liver. Furthermore, oxidative modifications and inactivation of the enzymes involved in the mitochondrial and/or peroxisomal beta-oxidation of fatty acids could contribute to fat accumulation in the liver.
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Affiliation(s)
- Vishnudutt Purohit
- Division of Metabolism and Health Effects, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5635 Fishers Lane, Bethesda, MD 20892, USA.
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Dias JV, Paredes BD, Mesquita LFQ, Carvalho AB, Kozlowski EO, Lessa AS, Takiya CM, Resende CMC, Coelho HSM, Campos-de-Carvalho AC, Rezende GFM, Goldenberg RCS. An ultrasound and histomorphological analysis of experimental liver cirrhosis in rats. Braz J Med Biol Res 2008; 41:992-9. [PMID: 19099152 DOI: 10.1590/s0100-879x2008001100008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Accepted: 11/03/2008] [Indexed: 02/08/2023] Open
Abstract
We investigated whether liver injury by dual exposure to ethanol and carbon tetrachloride (EtOH + CCl4) for 15 weeks would persist after hepatotoxic agents were removed (EtOH + CCl4/8wR). After 15 weeks of hepatic injury with ethanol (5.5%, m/v) and carbon tetrachloride (0.05, mL/kg, ip), 5 of 11 female Wistar rats were sacrificed. The other 6 rats were maintained for an additional 8 weeks without hepatotoxic agents. Ultrasonography showed increased liver echogenicity and dilation of portal vein caliber in both groups (EtOH + CCl4: 0.22 +/- 0.01 cm, P < 0.001; EtOH + CCl4/8wR: 0.21 +/- 0.02 cm, P < 0.01) vs control (0.16 +/- 0.02 cm). Histopathology showed regenerative nodules in both experimental groups. Histomorphometry revealed increased fibrosis content in both groups (EtOH + CCl4: 12.6 +/- 2.64%, P < 0.001; EtOH + CCl4/8wR: 10.4 +/- 1.36%, P < 0.05) vs control (2.2 +/- 1.21%). Collagen types I and III were increased in groups EtOH + CCl4 (collagen I: 2.5 +/- 1.3%, P < 0.01; collagen III: 1.3 +/- 0.2%, P < 0.05) and EtOH + CCl4/8wR (collagen I: 1.8 +/- 0.06%, P < 0.05; collagen III: 1.5 +/- 0.8%, P < 0.01) vs control (collagen I: 0.38 +/- 0.11%; collagen III: 0.25 +/- 0.06%). Tissue transglutaminase increased in both groups (EtOH + CCl4: 66.4 +/- 8%, P < 0.01; EtOH + CCl4/8wR: 58.8 +/- 21%, P < 0.01) vs control (7.9 +/- 0.8%). Cirrhosis caused by the association of CCl4-EtOH remained for at least 8 weeks after removal of these hepatotoxic agents. Ultrasound images can be a useful tool to evaluate advanced hepatic alterations.
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Affiliation(s)
- J V Dias
- Departamento de Clínica Médica, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
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Novo E, Parola M. Redox mechanisms in hepatic chronic wound healing and fibrogenesis. FIBROGENESIS & TISSUE REPAIR 2008; 1:5. [PMID: 19014652 PMCID: PMC2584013 DOI: 10.1186/1755-1536-1-5] [Citation(s) in RCA: 235] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Accepted: 10/13/2008] [Indexed: 12/24/2022]
Abstract
Reactive oxygen species (ROS) generated within cells or, more generally, in a tissue environment, may easily turn into a source of cell and tissue injury. Aerobic organisms have developed evolutionarily conserved mechanisms and strategies to carefully control the generation of ROS and other oxidative stress-related radical or non-radical reactive intermediates (that is, to maintain redox homeostasis), as well as to 'make use' of these molecules under physiological conditions as tools to modulate signal transduction, gene expression and cellular functional responses (that is, redox signalling). However, a derangement in redox homeostasis, resulting in sustained levels of oxidative stress and related mediators, can play a significant role in the pathogenesis of major human diseases characterized by chronic inflammation, chronic activation of wound healing and tissue fibrogenesis. This review has been designed to first offer a critical introduction to current knowledge in the field of redox research in order to introduce readers to the complexity of redox signalling and redox homeostasis. This will include ready-to-use key information and concepts on ROS, free radicals and oxidative stress-related reactive intermediates and reactions, sources of ROS in mammalian cells and tissues, antioxidant defences, redox sensors and, more generally, the major principles of redox signalling and redox-dependent transcriptional regulation of mammalian cells. This information will serve as a basis of knowledge to introduce the role of ROS and other oxidative stress-related intermediates in contributing to essential events, such as the induction of cell death, the perpetuation of chronic inflammatory responses, fibrogenesis and much more, with a major focus on hepatic chronic wound healing and liver fibrogenesis.
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Affiliation(s)
- Erica Novo
- Dipartimento di Medicina e Oncologia Sperimentale and Centro Interuniversitario di Fisiopatologia Epatica, Università degli Studi di Torino, Corso Raffaello 30, 10125 Torino, Italy
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Abstract
Although drugs of abuse have different chemical structures and interact with different protein targets, all appear to usurp common neuronal systems that regulate reward and motivation. Addiction is a complex disease that is thought to involve drug-induced changes in synaptic plasticity due to alterations in cell signaling, gene transcription, and protein synthesis. Recent evidence suggests that drugs of abuse interact with and change a common network of signaling pathways that include a subset of specific protein kinases. The best studied of these kinases are reviewed here and include extracellular signal-regulated kinase, cAMP-dependent protein kinase, cyclin-dependent protein kinase 5, protein kinase C, calcium/calmodulin-dependent protein kinase II, and Fyn tyrosine kinase. These kinases have been implicated in various aspects of drug addiction including acute drug effects, drug self-administration, withdrawal, reinforcement, sensitization, and tolerance. Identifying protein kinase substrates and signaling pathways that contribute to the addicted state may provide novel approaches for new pharmacotherapies to treat drug addiction.
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Affiliation(s)
- Anna M Lee
- Ernest Gallo Clinic and Research Center, Department of Neurology, University of California at San Francisco, Emeryville, CA 94608, USA
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Awasthi YC, Sharma R, Sharma A, Yadav S, Singhal SS, Chaudhary P, Awasthi S. Self-regulatory role of 4-hydroxynonenal in signaling for stress-induced programmed cell death. Free Radic Biol Med 2008; 45:111-8. [PMID: 18456001 PMCID: PMC2664084 DOI: 10.1016/j.freeradbiomed.2008.04.007] [Citation(s) in RCA: 273] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 04/02/2008] [Accepted: 04/06/2008] [Indexed: 11/26/2022]
Abstract
Within the last two decades, 4-hydroxynonenal has emerged as an important second messenger involved in the regulation of various cellular processes. Our recent studies suggest that HNE can induce apoptosis in various cells through the death receptor Fas (CD95)-mediated extrinsic pathway as well as through the p53-dependent intrinsic pathway. Interestingly, through its interaction with the nuclear protein Daxx, HNE can self-limit its apoptotic role by translocating Daxx to cytoplasm where it binds to Fas and inhibits Fas-mediated apoptosis. In this paper, after briefly describing recent studies on various biological activities of HNE, based on its interactions with Fas, Daxx, and p53, we speculate on possible mechanisms through which HNE may affect a multitude of cellular processes and draw a parallel between signaling roles of H(2)O(2) and HNE.
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Affiliation(s)
- Yogesh C Awasthi
- Department of Molecular Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX 76107-2699, USA.
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Abstract
PURPOSE OF REVIEW To update the reader with advances in epidemiology, genetics, detection, pathogenesis and therapy of alcohol-related liver disease. RECENT FINDINGS Ill-health due to alcohol abuse is improving in some nations but deteriorating in others. Oxidative and nitrosative stress are key to the pathogenesis of alcoholic liver disease, and there is now greater emphasis than previously on their development and role of cytochrome P450 2E1, on mitochondrial stress and disruption, (including elucidation of mitochondrial protection mechanisms) disturbance of signaling pathways and involvement of extrahepatic mediators like adiponectin. Treatment of alcoholic liver disease has stagnated, but transplantation is still favored and debated for end-stage cirrhosis. SUMMARY Basic and clinical research into the mechanisms of alcoholic liver disease is making headway, but has yet to produce safe and effective therapies for alcoholic hepatitis and for reversing cirrhosis.
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Interplay between oxidative stress and immunity in the progression of alcohol-mediated liver injury. Trends Mol Med 2008; 14:63-71. [PMID: 18222109 DOI: 10.1016/j.molmed.2007.12.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 12/02/2007] [Accepted: 12/03/2007] [Indexed: 12/13/2022]
Abstract
Inflammation is recognized increasingly as having an important role in the pathogenesis of alcoholic liver disease (ALD). Nonetheless, the mechanisms by which alcohol maintains hepatic inflammation are still characterized incompletely. Several studies have demonstrated that ethanol-induced oxidative stress promotes immune responses in ALD by stimulating both humoral and cellular reactions against liver proteins adducted to hydroxyethyl free radicals and several lipid peroxidation products. Moreover, ALD patients have autoantibodies targeting cytochrome P4502E1 and oxidized phospholipids. In both chronic alcohol-fed rats and heavy drinkers, the elevation of IgG against lipid peroxidation-derived antigens is associated with tumor necrosis factor-alpha production and the severity of liver inflammation. On this basis, we propose that allo- and autoimmune reactions associated with oxidative stress might contribute to fueling hepatic inflammation in ALD.
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Chen ZH, Saito Y, Yoshida Y, Noguchi N, Niki E. Regulation of GCL activity and cellular glutathione through inhibition of ERK phosphorylation. Biofactors 2008; 33:1-11. [PMID: 19276532 DOI: 10.1002/biof.5520330101] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Extracellular signal-regulated protein kinase (ERK), one of the mitogen-activated protein kinase, has been known to be involved in diverse cellular functions. In this work, we found that basically inhibition of this kinase in cultured cells markedly increased the gamma-glutamate-cysteine ligase (GCL; EC 6.3.2.2) activity, but without any considerable induction of the GCL genes. The increased GCL activity consequently elevated the cellular GSH level and eventually enhanced the cellular antioxidant capacity. Genetic inhibition of B-Raf, the upstream of ERK, also resulted in increased GCL activity and GSH level. Recent evidence also suggests that chronic pro-oxidant exposure results in the loss of ERK phosphorylation in vivo. Therefore, the findings in the present study suggest that inhibition of B-Raf/MEK/ERK pathway might be a promising physiological approach to up-regulate GCL activity and GSH. This study would also help us to understand the comprehensive role of the Raf/MEK/ERK pathway in overall physio/pathological conditions.
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Affiliation(s)
- Zhi-Hua Chen
- Human Stress Signal Research Center (HSSRC), National Institute of Advanced Industrial Science & Technology (AIST), Osaka, Japan
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