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Mastoridou EM, Goussia AC, Kanavaros P, Charchanti AV. Involvement of Lipophagy and Chaperone-Mediated Autophagy in the Pathogenesis of Non-Alcoholic Fatty Liver Disease by Regulation of Lipid Droplets. Int J Mol Sci 2023; 24:15891. [PMID: 37958873 PMCID: PMC10649352 DOI: 10.3390/ijms242115891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 10/30/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is defined as the accumulation of lipids in the form of lipid droplets in more than 5% of hepatocytes. It is regarded as a range of diverse pathologies, including simple steatosis and steatohepatitis. The structural characteristics of lipid droplets, along with their protein composition, mainly including perilipins, have been implicated in the etiology of the disease. These proteins have garnered increasing attention as a pivotal regulator since their levels and distinct expression appear to be associated with the progression from simple steatosis to steatohepatitis. Perilipins are target proteins of chaperone-mediated autophagy, and their degradation is a prerequisite for lipolysis and lipophagy to access the lipid core. Both lipophagy and chaperone-mediated autophagy have significant implications on the development of the disease, as evidenced by their upregulation during the initial phases of simple steatosis and their subsequent downregulation once steatosis is established. On the contrary, during steatohepatitis, the process of chaperone-mediated autophagy is enhanced, although lipophagy remains suppressed. Evidently, the reduced levels of autophagic pathways observed in simple steatosis serve as a defensive mechanism against lipotoxicity. Conversely, in steatohepatitis, chaperone-mediated autophagy fails to compensate for the continuous generation of small lipid droplets and thus cannot protect hepatocytes from lipotoxicity.
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Affiliation(s)
- Eleftheria M. Mastoridou
- Department of Anatomy-Histology-Embryology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (E.M.M.); (P.K.)
| | - Anna C. Goussia
- Department of Pathology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece;
| | - Panagiotis Kanavaros
- Department of Anatomy-Histology-Embryology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (E.M.M.); (P.K.)
| | - Antonia V. Charchanti
- Department of Anatomy-Histology-Embryology, Faculty of Medicine, School of Health Sciences, University of Ioannina, 45110 Ioannina, Greece; (E.M.M.); (P.K.)
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2
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Liang T, Kota J, Williams KE, Saxena R, Gawrieh S, Zhong X, Zimmers TA, Chalasani N. Dynamic Alterations to Hepatic MicroRNA-29a in Response to Long-Term High-Fat Diet and EtOH Feeding. Int J Mol Sci 2023; 24:14564. [PMID: 37834011 PMCID: PMC10572557 DOI: 10.3390/ijms241914564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 09/18/2023] [Accepted: 09/20/2023] [Indexed: 10/15/2023] Open
Abstract
MicroRNA-29a (miR-29a) is a well characterized fibro-inflammatory molecule and its aberrant expression is linked to a variety of pathological liver conditions. The long-term effects of a high-fat diet (HFD) in combination with different levels of EtOH consumption on miR-29a expression and liver pathobiology are unknown. Mice at 8 weeks of age were divided into five groups (calorie-matched diet plus water (CMD) as a control group, HFD plus water (HFD) as a liver disease group, HFD plus 2% EtOH (HFD + 2% E), HFD + 10% E, and HFD + 20% E as intervention groups) and fed for 4, 13, 26, or 39 weeks. At each time point, analyses were performed for liver weight/body weight (BW) ratio, AST/ALT ratio, as well as liver histology assessments, which included inflammation, estimated fat deposition, lipid area, and fibrosis. Hepatic miR-29a was measured and correlations with phenotypic traits were determined. Four-week feeding produced no differences between the groups on all collected phenotypic traits or miR-29a expression, while significant effects were observed after 13 weeks, with EtOH concentration-specific induction of miR-29a. A turning point for most of the collected traits was apparent at 26 weeks, and miR-29a was significantly down-regulated with increasing liver injury. Overall, miR-29a up-regulation was associated with a lower liver/BW ratio, fat deposition, inflammation, and fibrosis, suggesting a protective role of miR-29a against liver disease progression. A HFD plus increasing concentrations of EtOH produces progressive adverse effects on the liver, with no evidence of beneficial effects of low-dose EtOH consumption. Moreover, miR-29a up-regulation is associated with less severe liver injury.
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Affiliation(s)
- Tiebing Liang
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (K.E.W.); (S.G.); (N.C.)
| | - Janaiah Kota
- Ultragenyx Pharmaceuticals, Novato, CA 94949, USA;
| | - Kent E. Williams
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (K.E.W.); (S.G.); (N.C.)
| | - Romil Saxena
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA;
| | - Samer Gawrieh
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (K.E.W.); (S.G.); (N.C.)
| | - Xiaoling Zhong
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (X.Z.); (T.A.Z.)
| | - Teresa A. Zimmers
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (X.Z.); (T.A.Z.)
- Indiana Center for Musculoskeletal Health, Indianapolis, IN 46202, USA
- Richard L. Roudebush Veterans Administration Medical Center, Indianapolis, IN 46202, USA
| | - Naga Chalasani
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (K.E.W.); (S.G.); (N.C.)
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Mahalingam S, Bellamkonda R, Arumugam MK, Perumal SK, Yoon J, Casey C, Kharbanda K, Rasineni K. Glucagon-like peptide 1 receptor agonist, exendin-4, reduces alcohol-associated fatty liver disease. Biochem Pharmacol 2023; 213:115613. [PMID: 37209859 PMCID: PMC10351880 DOI: 10.1016/j.bcp.2023.115613] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/06/2023] [Accepted: 05/15/2023] [Indexed: 05/22/2023]
Abstract
Fatty liver is the earliest response to excessive ethanol consumption, which increases the susceptibility of the liver to develop advanced stage of liver disease. Our previous studies have revealed that chronic alcohol administration alters metabolic hormone levels and their functions. Of current interest to our laboratory is glucagon-like peptide 1 (GLP-1), a widely studied hormone known to reduce insulin resistance and hepatic fat accumulation in patients with metabolic-associated fatty liver disease. In this study, we examined the beneficial effects of exendin-4 (a GLP-1 receptor agonist) in an experimental rat model of ALD. Male Wistar rats were pair-fed the Lieber-DeCarli control or ethanol diet. After 4 weeks of this feeding regimen, a subset of rats in each group were intraperitoneally injected every other day with either saline or exendin-4 at a dose of 3 nmol/kg/day (total 13 doses) while still being fed their respective diet. At the end of the treatment, rats were fasted for 6 h and glucose tolerance test was conducted. The following day, the rats were euthanized, and the blood and tissue samples collected for subsequent analysis. We found that exendin-4 treatment had no significant effect on body weight gain among the experimental groups. Exendin-4-treated ethanol rats exhibited improved alcohol-induced alterations in liver/body weight and adipose/body weight ratio, serum ALT, NEFA, insulin, adiponectin and hepatic triglyceride levels. Reduction in indices of hepatic steatosis in exendin-4 treated ethanol-fed rats was attributed to improved insulin signaling and fat metabolism. These results strongly suggest that exendin-4 mitigates alcohol-associated hepatic steatosis by regulating fat metabolism.
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Affiliation(s)
- Sundararajan Mahalingam
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Ramesh Bellamkonda
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Madan Kumar Arumugam
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Sathish Kumar Perumal
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Jessica Yoon
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Carol Casey
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Kusum Kharbanda
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Karuna Rasineni
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States.
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4
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Ji C. Molecular Factors and Pathways of Hepatotoxicity Associated with HIV/SARS-CoV-2 Protease Inhibitors. Int J Mol Sci 2023; 24:ijms24097938. [PMID: 37175645 PMCID: PMC10178330 DOI: 10.3390/ijms24097938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
Antiviral protease inhibitors are peptidomimetic molecules that block the active catalytic center of viral proteases and, thereby, prevent the cleavage of viral polyprotein precursors into maturation. They continue to be a key class of antiviral drugs that can be used either as boosters for other classes of antivirals or as major components of current regimens in therapies for the treatment of infections with human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, sustained/lifelong treatment with the drugs or drugs combined with other substance(s) often leads to severe hepatic side effects such as lipid abnormalities, insulin resistance, and hepatotoxicity. The underlying pathogenic mechanisms are not fully known and are under continuous investigation. This review focuses on the general as well as specific molecular mechanisms of the protease inhibitor-induced hepatotoxicity involving transporter proteins, apolipoprotein B, cytochrome P450 isozymes, insulin-receptor substrate 1, Akt/PKB signaling, lipogenic factors, UDP-glucuronosyltransferase, pregnane X receptor, hepatocyte nuclear factor 4α, reactive oxygen species, inflammatory cytokines, off-target proteases, and small GTPase Rab proteins related to ER-Golgi trafficking, organelle stress, and liver injury. Potential pharmaceutical/therapeutic solutions to antiviral drug-induced hepatic side effects are also discussed.
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Affiliation(s)
- Cheng Ji
- Research Center for Liver Disease, GI/Liver Division, Department of Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA 90089, USA
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5
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Zhao Y, Dong Q, Geng Y, Ma C, Shao Q. Dynamic Regulation of Lipid Droplet Biogenesis in Plant Cells and Proteins Involved in the Process. Int J Mol Sci 2023; 24:ijms24087476. [PMID: 37108639 PMCID: PMC10138601 DOI: 10.3390/ijms24087476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 04/11/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023] Open
Abstract
Lipid droplets (LDs) are ubiquitous, dynamic organelles found in almost all organisms, including animals, protists, plants and prokaryotes. The cell biology of LDs, especially biogenesis, has attracted increasing attention in recent decades because of their important role in cellular lipid metabolism and other newly identified processes. Emerging evidence suggests that LD biogenesis is a highly coordinated and stepwise process in animals and yeasts, occurring at specific sites of the endoplasmic reticulum (ER) that are defined by both evolutionarily conserved and organism- and cell type-specific LD lipids and proteins. In plants, understanding of the mechanistic details of LD formation is elusive as many questions remain. In some ways LD biogenesis differs between plants and animals. Several homologous proteins involved in the regulation of animal LD formation in plants have been identified. We try to describe how these proteins are synthesized, transported to the ER and specifically targeted to LD, and how these proteins participate in the regulation of LD biogenesis. Here, we review current work on the molecular processes that control LD formation in plant cells and highlight the proteins that govern this process, hoping to provide useful clues for future research.
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Affiliation(s)
- Yiwu Zhao
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan 250358, China
| | - Qingdi Dong
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan 250358, China
| | - Yuhu Geng
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan 250358, China
| | - Changle Ma
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan 250358, China
| | - Qun Shao
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan 250358, China
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6
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Mak KM, Wu C, Cheng CP. Lipid droplets, the Holy Grail of hepatic stellate cells: In health and hepatic fibrosis. Anat Rec (Hoboken) 2022; 306:983-1010. [PMID: 36516055 DOI: 10.1002/ar.25138] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/07/2022] [Accepted: 11/29/2022] [Indexed: 12/15/2022]
Abstract
Lipid droplets (LDs) are distinct morphological markers of hepatic stellate cells (HSCs). They are composed of a core of predominantly retinyl esters and triacylglycerols surrounded by a phospholipid layer; the latter harbors perilipins 2, 3, and 5, which help control LD lipolysis. Electron microscopy distinguishes between Types I and II LDs. Type I LDs are surrounded by acid phosphatase-positive lysosomes, which likely digest LDs. LD count and retinoid concentration are modulated by vitamin A intake. Alcohol consumption depletes hepatic retinoids and HSC LDs, with concomitant transformation of HSCs to fibrogenic myofibroblast-like cells. LD loss and accompanying HSC activation occur in HSC cell culture models. Loss of LDs is a consequence of and not a prerequisite for HSC activation. LDs are endowed with enzymes for synthesizing retinyl esters and triacylglycerols as well as neutral lipases and lysosomal acid lipase for breaking down LDs. HSCs have two distinct metabolic LD pools: an "original" pool in quiescent HSCs and a "new" pool emerging in HSC activation; this two-pool model provides a platform for analyzing LD dynamics in HSC activation. Besides lipolysis, LDs are degraded by lipophagy; however, the coordination between and relative contributions of these two pathways to LD removal are unclear. While induction of autophagy accelerates LD loss in quiescent HSCs and promotes HSC activation, blocking autophagy impairs LD degradation and inhibits HSC activation and fibrosis. This article is a critique of five decades of investigations into the morphology, molecular structure, synthesis, and degradation of LDs associated with HSC activation and fibrosis.
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Affiliation(s)
- Ki M Mak
- Department of Medical Education and Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Catherine Wu
- Department of Medical Education and Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Christopher P Cheng
- Department of Medical Education and Center for Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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7
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Ge S, Zhang RX, Wang YF, Sun P, Chu J, Li J, Sun P, Wang J, Hetherington AM, Liang YK. The Arabidopsis Rab protein RABC1 affects stomatal development by regulating lipid droplet dynamics. THE PLANT CELL 2022; 34:4274-4292. [PMID: 35929087 PMCID: PMC9614440 DOI: 10.1093/plcell/koac239] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/13/2022] [Indexed: 05/13/2023]
Abstract
Lipid droplets (LDs) are evolutionarily conserved organelles that serve as hubs of cellular lipid and energy metabolism in virtually all organisms. Mobilization of LDs is important in light-induced stomatal opening. However, whether and how LDs are involved in stomatal development remains unknown. We show here that Arabidopsis thaliana LIPID DROPLETS AND STOMATA 1 (LDS1)/RABC1 (At1g43890) encodes a member of the Rab GTPase family that is involved in regulating LD dynamics and stomatal morphogenesis. The expression of RABC1 is coordinated with the different phases of stomatal development. RABC1 targets to the surface of LDs in response to oleic acid application in a RABC1GEF1-dependent manner. RABC1 physically interacts with SEIPIN2/3, two orthologues of mammalian seipin, which function in the formation of LDs. Disruption of RABC1, RABC1GEF1, or SEIPIN2/3 resulted in aberrantly large LDs, severe defects in guard cell vacuole morphology, and stomatal function. In conclusion, these findings reveal an aspect of LD function and uncover a role for lipid metabolism in stomatal development in plants.
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Affiliation(s)
| | | | - Yi-Fei Wang
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
- Hubei Hongshan Laboratory, Wuhan 430070, China
| | - Pengyue Sun
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
- Hubei Hongshan Laboratory, Wuhan 430070, China
| | - Jiaheng Chu
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jiao Li
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Peng Sun
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jianbo Wang
- State Key Laboratory of Hybrid Rice, Department of Plant Sciences, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Alistair M Hetherington
- School of Biological Sciences, Life Sciences Building, University of Bristol, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
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8
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Neuman MG, Seitz HK, Tuma PL, Osna NA, Casey CA, Kharbanda KK, Cohen LB, Malnick SDH, Adhikari R, Mitra R, Dagur RS, Ganesan M, Srinivas C, Madan Kumar A, New-Aaron M, Poluektova L, Thomes PG, Rasineni K, Opris M, Teschke R. Alcohol: basic and translational research; 15th annual Charles Lieber &1st Samuel French satellite symposium. Exp Mol Pathol 2022; 126:104750. [PMID: 35192844 PMCID: PMC9167794 DOI: 10.1016/j.yexmp.2022.104750] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 12/28/2021] [Accepted: 01/24/2022] [Indexed: 02/05/2023]
Abstract
The present review is based on the research presented at the symposium dedicated to the legacy of the two scientists that made important discoveries in the field of alcohol-induced liver damage: Professors C.S. Lieber and S.W. French. The invited speakers described pharmacological, toxicological and patho-physiological effects of alcohol misuse. Moreover, genetic biomarkers determining adverse drug reactions due to interactions between therapeutics used for chronic or infectious diseases and alcohol exposure were discussed. The researchers presented their work in areas of alcohol-induced impairment in lipid protein trafficking and endocytosis, as well as the role of lipids in the development of fatty liver. The researchers showed that alcohol leads to covalent modifications that promote hepatic dysfunction and injury. We concluded that using new advanced techniques and research ideas leads to important discoveries in science.
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Affiliation(s)
- Manuela G Neuman
- In Vitro Drug Safety and Biotechnology, Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada.
| | - Helmut K Seitz
- Centre of Liver and Alcohol Diseases, Ethianum Clinic, University of Heidelberg, Germany
| | - Pamela L Tuma
- The Catholic University of America, Department of Biology, Washington, DC 20064, USA
| | - Natalia A Osna
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Carol A Casey
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Kusum K Kharbanda
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Lawrence B Cohen
- Division of Gastroenterology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Canada
| | - Steve D H Malnick
- Department of Internal Medicine C, Kaplan Medical Center, Affiliated Hebrew University, Jerusalem, Israel
| | - Raghabendra Adhikari
- The Catholic University of America, Department of Biology, Washington, DC 20064, USA
| | - Ramyajit Mitra
- The Catholic University of America, Department of Biology, Washington, DC 20064, USA
| | - Raghubendra Singh Dagur
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Murali Ganesan
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Chava Srinivas
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Arumugam Madan Kumar
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Moses New-Aaron
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Larisa Poluektova
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Paul G Thomes
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Karuna Rasineni
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, and Department of Internal Medicine, Section of Gastroenterology-Hepatology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Mihai Opris
- In Vitro Drug Safety and Biotechnology, Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada; Family Medicine Clinic CAR, Bucharest, Romania
| | - Rolf Teschke
- Department of Internal Medicine II, Division of Gastroenterology and Hepatology, Klinikum Hanau, Hanau, Academic Teaching Hospital of the Medical Faculty, Goethe University Frankfurt/ Main, Frankfurt/Main, Germany
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9
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Patel A, Perl A. Redox Control of Integrin-Mediated Hepatic Inflammation in Systemic Autoimmunity. Antioxid Redox Signal 2022; 36:367-388. [PMID: 34036799 PMCID: PMC8982133 DOI: 10.1089/ars.2021.0068] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/12/2021] [Accepted: 05/13/2021] [Indexed: 12/20/2022]
Abstract
Significance: Systemic autoimmunity affects 3%-5% of the population worldwide. Systemic lupus erythematosus (SLE) is a prototypical form of such condition, which affects 20-150 of 100,000 people globally. Liver dysfunction, defined by increased immune cell infiltration into the hepatic parenchyma, is an understudied manifestation that affects up to 20% of SLE patients. Autoimmunity in SLE involves proinflammatory lineage specification in the immune system that occurs with oxidative stress and profound changes in cellular metabolism. As the primary metabolic organ of the body, the liver is uniquely capable to encounter oxidative stress through first-pass derivatization and filtering of waste products. Recent Advances: The traffic of immune cells from their development through recirculation in the liver is guided by cell adhesion molecules (CAMs) and integrins, cell surface proteins that tightly anchor cells together. The surface expression of CAMs and integrins is regulated via endocytic traffic that is sensitive to oxidative stress. Reactive oxygen species (ROS) that elicit oxidative stress in the liver may originate from the mitochondria, the cytosol, or the cell membrane. Critical Issues: While hepatic ROS production is a source of vulnerability, it also modulates the development and function of the immune system. In turn, the liver employs antioxidant defense mechanisms to protect itself from damage that can be harnessed to serve as therapeutic mechanisms against autoimmunity, inflammation, and development of hepatocellular carcinoma. Future Directions: This review is aimed at delineating redox control of integrin signaling in the liver and checkpoints of regulatory impact that can be targeted for treatment of inflammation in systemic autoimmunity. Antioxid. Redox Signal. 36, 367-388.
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Affiliation(s)
- Akshay Patel
- Division of Rheumatology, Department of Medicine, College of Medicine, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Microbiology and Immunology, College of Medicine, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Biochemistry and Molecular Biology, College of Medicine, State University of New York Upstate Medical University, Syracuse, New York, USA
| | - Andras Perl
- Division of Rheumatology, Department of Medicine, College of Medicine, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Microbiology and Immunology, College of Medicine, State University of New York Upstate Medical University, Syracuse, New York, USA
- Department of Biochemistry and Molecular Biology, College of Medicine, State University of New York Upstate Medical University, Syracuse, New York, USA
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10
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Macke AJ, Petrosyan A. Alcohol and Prostate Cancer: Time to Draw Conclusions. Biomolecules 2022; 12:375. [PMID: 35327568 PMCID: PMC8945566 DOI: 10.3390/biom12030375] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/18/2022] [Accepted: 02/24/2022] [Indexed: 01/25/2023] Open
Abstract
It has been a long-standing debate in the research and medical societies whether alcohol consumption is linked to the risk of prostate cancer (PCa). Many comprehensive studies from different geographical areas and nationalities have shown that moderate and heavy drinking is positively correlated with the development of PCa. Nevertheless, some observations could not confirm that such a correlation exists; some even suggest that wine consumption could prevent or slow prostate tumor growth. Here, we have rigorously analyzed the evidence both for and against the role of alcohol in PCa development. We found that many of the epidemiological studies did not consider other, potentially critical, factors, including diet (especially, low intake of fish, vegetables and linoleic acid, and excessive use of red meat), smoking, family history of PCa, low physical activity, history of high sexual activities especially with early age of first intercourse, and sexually transmitted infections. In addition, discrepancies between observations come from selectivity criteria for control groups, questionnaires about the type and dosage of alcohol, and misreported alcohol consumption. The lifetime history of alcohol consumption is critical given that a prostate tumor is typically slow-growing; however, many epidemiological observations that show no association monitored only current or relatively recent drinking status. Nevertheless, the overall conclusion is that high alcohol intake, especially binge drinking, is associated with increased risk for PCa, and this effect is not limited to any type of beverage. Alcohol consumption is also directly linked to PCa lethality as it may accelerate the growth of prostate tumors and significantly shorten the time for the progression to metastatic PCa. Thus, we recommend immediately quitting alcohol for patients diagnosed with PCa. We discuss the features of alcohol metabolism in the prostate tissue and the damaging effect of ethanol metabolites on intracellular organization and trafficking. In addition, we review the impact of alcohol consumption on prostate-specific antigen level and the risk for benign prostatic hyperplasia. Lastly, we highlight the known mechanisms of alcohol interference in prostate carcinogenesis and the possible side effects of alcohol during androgen deprivation therapy.
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Affiliation(s)
- Amanda J. Macke
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA;
| | - Armen Petrosyan
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA;
- The Fred and Pamela Buffett Cancer Center, Omaha, NE 68198, USA
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11
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Casey CA, Macke AJ, Gough RR, Pachikov AN, Morris ME, Thomes PG, Kubik JL, Holzapfel MS, Petrosyan A. Alcohol-Induced Liver Injury: Down-regulation and Redistribution of Rab3D Results in Atypical Protein Trafficking. Hepatol Commun 2022; 6:374-388. [PMID: 34494400 PMCID: PMC8793998 DOI: 10.1002/hep4.1811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 08/05/2021] [Accepted: 08/05/2021] [Indexed: 12/17/2022] Open
Abstract
Previous work from our laboratories has identified multiple defects in endocytosis, protein trafficking, and secretion, along with altered Golgi function after alcohol administration. Manifestation of alcohol-associated liver disease (ALD) is associated with an aberrant function of several hepatic proteins, including asialoglycoprotein receptor (ASGP-R), their atypical distribution at the plasma membrane (PM), and secretion of their abnormally glycosylated forms into the bloodstream, but trafficking mechanism is unknown. Here we report that a small GTPase, Rab3D, known to be involved in exocytosis, secretion, and vesicle trafficking, shows ethanol (EtOH)-impaired function, which plays an important role in Golgi disorganization. We used multiple approaches and cellular/animal models of ALD, along with Rab3D knockout (KO) mice and human tissue from patients with ALD. We found that Rab3D resides primarily in trans- and cis-faces of Golgi; however, EtOH treatment results in Rab3D redistribution from trans-Golgi to cis-medial-Golgi. Cells lacking Rab3D demonstrate enlargement of Golgi, especially its distal compartments. We identified that Rab3D is required for coat protein I (COPI) vesiculation in Golgi, and conversely, COPI is critical for intra-Golgi distribution of Rab3D. Rab3D/COPI association was altered not only in the liver of patients with ALD but also in the donors consuming alcohol without steatosis. In Rab3D KO mice, hepatocytes experience endoplasmic reticulum (ER) stress, and EtOH administration activates apoptosis. Notably, in these cells, ASGP-R, despite incomplete glycosylation, can still reach cell surface through ER-PM junctions. This mimics the effects seen with EtOH-induced liver injury. Conclusion: We revealed that down-regulation of Rab3D contributes significantly to EtOH-induced Golgi disorganization, and abnormally glycosylated ASGP-R is excreted through ER-PM connections, bypassing canonical (ER→Golgi→PM) anterograde transportation. This suggests that ER-PM sites may be a therapeutic target for ALD.
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Affiliation(s)
- Carol A. Casey
- Department of Research ServiceOmaha Western Iowa Health Care System, VA ServiceOmahaNEUSA
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Amanda J. Macke
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Ryan R. Gough
- Department of Research ServiceOmaha Western Iowa Health Care System, VA ServiceOmahaNEUSA
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNEUSA
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Artem N. Pachikov
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
- The Fred and Pamela Buffett Cancer CenterOmahaNEUSA
| | - Mary E. Morris
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Paul G. Thomes
- Department of Research ServiceOmaha Western Iowa Health Care System, VA ServiceOmahaNEUSA
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Jacy L. Kubik
- Department of Research ServiceOmaha Western Iowa Health Care System, VA ServiceOmahaNEUSA
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Melissa S. Holzapfel
- Department of Pathology and MicrobiologyUniversity of Nebraska Medical CenterOmahaNEUSA
| | - Armen Petrosyan
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNEUSA
- The Fred and Pamela Buffett Cancer CenterOmahaNEUSA
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12
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Thomes PG, Rasineni K, Saraswathi V, Kharbanda KK, Clemens DL, Sweeney SA, Kubik JL, Donohue TM, Casey CA. Natural Recovery by the Liver and Other Organs after Chronic Alcohol Use. Alcohol Res 2021; 41:05. [PMID: 33868869 PMCID: PMC8041137 DOI: 10.35946/arcr.v41.1.05] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Chronic, heavy alcohol consumption disrupts normal organ function and causes structural damage in virtually every tissue of the body. Current diagnostic terminology states that a person who drinks alcohol excessively has alcohol use disorder. The liver is especially susceptible to alcohol-induced damage. This review summarizes and describes the effects of chronic alcohol use not only on the liver, but also on other selected organs and systems affected by continual heavy drinking—including the gastrointestinal tract, pancreas, heart, and bone. Most significantly, the recovery process after cessation of alcohol consumption (abstinence) is explored. Depending on the organ and whether there is relapse, functional recovery is possible. Even after years of heavy alcohol use, the liver has a remarkable regenerative capacity and, following alcohol removal, can recover a significant portion of its original mass and function. Other organs show recovery after abstinence as well. Data on studies of both heavy alcohol use among humans and animal models of chronic ethanol feeding are discussed. This review describes how (or whether) each organ/tissue metabolizes ethanol, as metabolism influences the organ’s degree of injury. Damage sustained by the organ/tissue is reviewed, and evidence for recovery during abstinence is presented.
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Affiliation(s)
- Paul G Thomes
- Department of Internal Medicine, Section of Gastroenterology, University of Nebraska Medical Center, Omaha, Nebraska.,Research Service, U.S. Department of Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Karuna Rasineni
- Department of Internal Medicine, Section of Gastroenterology, University of Nebraska Medical Center, Omaha, Nebraska.,Research Service, U.S. Department of Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Viswanathan Saraswathi
- Research Service, U.S. Department of Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska.,Department of Internal Medicine, Section of Diabetes, Endocrinology, and Metabolism, University of Nebraska Medical Center, Omaha, Nebraska
| | - Kusum K Kharbanda
- Department of Internal Medicine, Section of Gastroenterology, University of Nebraska Medical Center, Omaha, Nebraska.,Research Service, U.S. Department of Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Dahn L Clemens
- Department of Internal Medicine, Section of Cardiovascular Medicine, University of Nebraska Medical Center, Omaha, Nebraska.,Fred & Pamela Buffet Cancer Center, University of Nebraska Medical Center, Omaha, Nebraska
| | - Sarah A Sweeney
- Department of Internal Medicine, Section of Gastroenterology, University of Nebraska Medical Center, Omaha, Nebraska.,Research Service, U.S. Department of Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Jacy L Kubik
- Department of Internal Medicine, Section of Gastroenterology, University of Nebraska Medical Center, Omaha, Nebraska.,Research Service, U.S. Department of Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Terrence M Donohue
- Department of Internal Medicine, Section of Gastroenterology, University of Nebraska Medical Center, Omaha, Nebraska.,Research Service, U.S. Department of Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Carol A Casey
- Department of Internal Medicine, Section of Gastroenterology, University of Nebraska Medical Center, Omaha, Nebraska.,Research Service, U.S. Department of Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
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13
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Rasineni K, Jordan CW, Thomes PG, Kubik JL, Staab EM, Sweeney SA, Talmon GA, Donohue TM, McNiven MA, Kharbanda KK, Casey CA. Contrasting Effects of Fasting on Liver-Adipose Axis in Alcohol-Associated and Non-alcoholic Fatty Liver. Front Physiol 2021; 12:625352. [PMID: 33746771 PMCID: PMC7966527 DOI: 10.3389/fphys.2021.625352] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/02/2021] [Indexed: 01/15/2023] Open
Abstract
Background: Fatty liver, a major health problem worldwide, is the earliest pathological change in the progression of alcohol-associated (AFL) and non-alcoholic fatty liver disease (NAFL). Though the causes of AFL and NAFL differ, both share similar histological and some common pathophysiological characteristics. In this study, we sought to examine mechanisms responsible for lipid dynamics in liver and adipose tissue in the setting of AFL and NAFL in response to 48 h of fasting. Methods: Male rats were fed Lieber-DeCarli liquid control or alcohol-containing diet (AFL model), chow or high-fat pellet diet (NAFL model). After 6-8 weeks of feeding, half of the rats from each group were fasted for 48 h while the other half remained on their respective diets. Following sacrifice, blood, adipose, and the liver were collected for analysis. Results: Though rats fed AFL and NAFL diets both showed fatty liver, the physiological mechanisms involved in the development of each was different. Here, we show that increased hepatic de novo fatty acid synthesis, increased uptake of adipose-derived free fatty acids, and impaired triglyceride breakdown contribute to the development of AFL. In the case of NAFL, however, increased dietary fatty acid uptake is the major contributor to hepatic steatosis. Likewise, the response to starvation in the two fatty liver disease models also varied. While there was a decrease in hepatic steatosis after fasting in ethanol-fed rats, the control, chow and high-fat diet-fed rats showed higher levels of hepatic steatosis than pair-fed counterparts. This diverse response was a result of increased adipose lipolysis in all experimental groups except fasted ethanol-fed rats. Conclusion: Even though AFL and NAFL are nearly histologically indistinguishable, the physiological mechanisms that cause hepatic fat accumulation are different as are their responses to starvation.
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Affiliation(s)
- Karuna Rasineni
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
| | - Clayton W. Jordan
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Paul G. Thomes
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
| | - Jacy L. Kubik
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
| | - Elizabeth M. Staab
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Sarah A. Sweeney
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
| | - Geoffrey A. Talmon
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Terrence M. Donohue
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Mark A. McNiven
- Department of Biochemistry and Molecular Biology and the Center for Digestive Diseases, Mayo Clinic, Rochester, MN, United States
| | - Kusum K. Kharbanda
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Carol A. Casey
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, United States
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE, United States
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
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14
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Casey CA, Donohue TM, Kubik JL, Kumar V, Naldrett MJ, Woods NT, Frisbie CP, McNiven MA, Thomes PG. Lipid droplet membrane proteome remodeling parallels ethanol-induced hepatic steatosis and its resolution. J Lipid Res 2021; 62:100049. [PMID: 33617872 PMCID: PMC8010705 DOI: 10.1016/j.jlr.2021.100049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 01/29/2021] [Accepted: 02/10/2021] [Indexed: 10/25/2022] Open
Abstract
Lipid droplets (LDs) are composed of neutral lipids enclosed in a phospholipid monolayer, which harbors membrane-associated proteins that regulate LD functions. Despite the crucial role of LDs in lipid metabolism, remodeling of LD protein composition in disease contexts, such as steatosis, remains poorly understood. We hypothesized that chronic ethanol consumption, subsequent abstinence from ethanol, or fasting differentially affects the LD membrane proteome content and that these changes influence how LDs interact with other intracellular organelles. Here, male Wistar rats were pair-fed liquid control or ethanol diets for 6 weeks, and then, randomly chosen animals from both groups were either refed a control diet for 7 days or fasted for 48 h before euthanizing. From all groups, LD membrane proteins from purified liver LDs were analyzed immunochemically and by MS proteomics. Liver LD numbers and sizes were greater in ethanol-fed rats than in pair-fed control, 7-day refed, or fasted rats. Compared with control rats, ethanol feeding markedly altered the LD membrane proteome, enriching LD structural perilipins and proteins involved in lipid biosynthesis, while lowering LD lipase levels. Ethanol feeding also lowered LD-associated mitochondrial and lysosomal proteins. In 7-day refed (i.e., ethanol-abstained) or fasted-ethanol-fed rats, we detected distinct remodeling of the LD proteome, as judged by lower levels of lipid biosynthetic proteins, and enhanced LD interaction with mitochondria and lysosomes. Our study reveals evidence of significant remodeling of the LD membrane proteome that regulates ethanol-induced steatosis, its resolution after withdrawal and abstinence, and changes in LD interactions with other intracellular organelles.
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Affiliation(s)
- Carol A Casey
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, USA; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Terrence M Donohue
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, USA; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Jacy L Kubik
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, USA; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Vikas Kumar
- Department of Genetics Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, USA; Mass Spectrometry and Proteomics Core Facility, University of Nebraska Medical Center, Omaha, NE, USA
| | - Michael J Naldrett
- Nebraska Center for Biotechnology, University of Nebraska-Lincoln, NE, USA
| | - Nicholas T Woods
- Eppley Institute, University of Nebraska Medical Center, Omaha, NE, USA
| | - Cole P Frisbie
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Mark A McNiven
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Paul G Thomes
- VA-Nebraska-Western Iowa Health Care System, Department of Veterans' Affairs, Omaha, NE, USA; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE, USA; Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA.
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15
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Valcin JA, Udoh US, Swain TM, Andringa KK, Patel CR, Al Diffalha S, Baker PRS, Gamble KL, Bailey SM. Alcohol and Liver Clock Disruption Increase Small Droplet Macrosteatosis, Alter Lipid Metabolism and Clock Gene mRNA Rhythms, and Remodel the Triglyceride Lipidome in Mouse Liver. Front Physiol 2020; 11:1048. [PMID: 33013449 PMCID: PMC7504911 DOI: 10.3389/fphys.2020.01048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 07/30/2020] [Indexed: 12/12/2022] Open
Abstract
Heavy alcohol drinking dysregulates lipid metabolism, promoting hepatic steatosis – the first stage of alcohol-related liver disease (ALD). The molecular circadian clock plays a major role in synchronizing daily rhythms in behavior and metabolism and clock disruption can cause pathology, including liver disease. Previous studies indicate that alcohol consumption alters liver clock function, but the impact alcohol or clock disruption, or both have on the temporal control of hepatic lipid metabolism and injury remains unclear. Here, we undertook studies to determine whether genetic disruption of the liver clock exacerbates alterations in lipid metabolism and worsens steatosis in alcohol-fed mice. To address this question, male liver-specific Bmal1 knockout (LKO) and flox/flox (Fl/Fl) control mice were fed a control or alcohol-containing diet for 5 weeks. Alcohol significantly dampened diurnal rhythms of mRNA levels in clock genes Bmal1 and Dbp, phase advanced Nr1d1/REV-ERBα, and induced arrhythmicity in Clock, Noct, and Nfil3/E4BP4, with further disruption in livers of LKO mice. Alcohol-fed LKO mice exhibited higher plasma triglyceride (TG) and different time-of-day patterns of hepatic TG and macrosteatosis, with elevated levels of small droplet macrosteatosis compared to alcohol-fed Fl/Fl mice. Diurnal rhythms in mRNA levels of lipid metabolism transcription factors (Srebf1, Nr1h2, and Ppara) were significantly altered by alcohol and clock disruption. Alcohol and/or clock disruption significantly altered diurnal rhythms in mRNA levels of fatty acid (FA) synthesis and oxidation (Acaca/b, Mlycd, Cpt1a, Fasn, Elovl5/6, and Fads1/2), TG turnover (Gpat1, Agpat1/2, Lpin1/2, Dgat2, and Pnpla2/3), and lipid droplet (Plin2/5, Lipe, Mgll, and Abdh5) genes, along with protein abundances of p-ACC, MCD, and FASN. Lipidomics analyses showed that alcohol, clock disruption, or both significantly altered FA saturation and remodeled the FA composition of the hepatic TG pool, with higher percentages of several long and very long chain FA in livers of alcohol-fed LKO mice. In conclusion, these results show that the liver clock is important for maintaining temporal control of hepatic lipid metabolism and that disrupting the liver clock exacerbates alcohol-related hepatic steatosis.
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Affiliation(s)
- Jennifer A Valcin
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Uduak S Udoh
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Telisha M Swain
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Kelly K Andringa
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Chirag R Patel
- Division of Anatomic Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Sameer Al Diffalha
- Division of Anatomic Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
| | | | - Karen L Gamble
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Shannon M Bailey
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, United States
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16
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Abstract
The rising incidence of alcohol-related liver disease (ALD) demands making urgent progress in understanding the fundamental molecular basis of alcohol-related hepatocellular damage. One of the key early events accompanying chronic alcohol usage is the accumulation of lipid droplets (LDs) in the hepatocellular cytoplasm. LDs are far from inert sites of neutral lipid storage; rather, they represent key organelles that play vital roles in the metabolic state of the cell. In this review, we will examine the biology of these structures and outline recent efforts being made to understand the effects of alcohol exposure on the biogenesis, catabolism, and motility of LDs and how their dynamic nature is perturbed in the context of ALD.
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Affiliation(s)
- Ryan J. Schulze
- Department of Biochemistry and Molecular Biology and the Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA,Corresponding author. Department of Biochemistry and Molecular Biology and the Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA. (R.J. Schulze)
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology, and Therapeutics, The University of Kansas Medical Center, Kansas City, KS, USA
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17
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Groebner JL, Girón-Bravo MT, Rothberg ML, Adhikari R, Tuma DJ, Tuma PL. Alcohol-induced microtubule acetylation leads to the accumulation of large, immobile lipid droplets. Am J Physiol Gastrointest Liver Physiol 2019; 317:G373-G386. [PMID: 31373507 PMCID: PMC6842993 DOI: 10.1152/ajpgi.00026.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although steatosis (fatty liver) is a clinically well-described early stage of alcoholic liver disease, surprisingly little is known about how it promotes hepatotoxicity. We have shown that ethanol consumption leads to microtubule hyperacetylation that can explain ethanol-induced defects in protein trafficking. Because almost all steps of the lipid droplet life cycle are microtubule dependent and because microtubule acetylation promotes adipogenesis, we examined droplet dynamics in ethanol-treated cells. In WIF-B cells treated with ethanol and/or oleic acid (a fatty acid associated with the "Western" diet), we found that ethanol dramatically increased lipid droplet numbers and led to the formation of large, peripherally located droplets. Enhanced droplet formation required alcohol dehydrogenase-mediated ethanol metabolism, and peripheral droplet distributions required intact microtubules. We also determined that ethanol-induced microtubule acetylation led to impaired droplet degradation. Live-cell imaging revealed that droplet motility was microtubule dependent and that droplets were virtually stationary in ethanol-treated cells. To determine more directly whether microtubule hyperacetylation could explain impaired droplet motility, we overexpressed the tubulin-specific acetyltransferase αTAT1 to promote microtubule acetylation in the absence of alcohol. Droplet motility was impaired in αTAT1-expressing cells but to a lesser extent than in ethanol-treated cells. However, in both cases, the large immotile droplets (but not small motile ones) colocalized with dynein and dynactin (but not kinesin), implying that altered droplet-motor microtubule interactions may explain altered dynamics. These studies further suggest that modulating cellular acetylation is a potential strategy for treating alcoholic liver disease.NEW & NOTEWORTHY Chronic alcohol consumption with the "Western diet" enhances the development of fatty liver and leads to impaired droplet motility, which may have serious deletrious effects on hepatocyte function.
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Affiliation(s)
| | | | - Mia L. Rothberg
- 1Department of Biology, The Catholic University of America, Washington D. C.
| | | | - Dean J. Tuma
- 2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Pamela L. Tuma
- 1Department of Biology, The Catholic University of America, Washington D. C.
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18
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Rasineni K, Kubik JL, Casey CA, Kharbanda KK. Inhibition of Ghrelin Activity by Receptor Antagonist [d-Lys-3] GHRP-6 Attenuates Alcohol-Induced Hepatic Steatosis by Regulating Hepatic Lipid Metabolism. Biomolecules 2019; 9:biom9100517. [PMID: 31546643 PMCID: PMC6843513 DOI: 10.3390/biom9100517] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 01/13/2023] Open
Abstract
Alcoholic steatosis, characterized by an accumulation of triglycerides in hepatocytes, is one of the earliest pathological changes in the progression of alcoholic liver disease. In our previous study, we showed that alcohol-induced increase in serum ghrelin levels impair insulin secretion from pancreatic β-cells. The consequent reduction in the circulating insulin levels promote adipose-derived fatty acid mobilization to ultimately contribute to hepatic steatosis. In this study, we determined whether inhibition of ghrelin activity in chronic alcohol-fed rats could improve hepatic lipid homeostasis at the pancreas-adipose-liver axis. Adult Wistar rats were fed Lieber-DeCarli control or an ethanol liquid diet for 7 weeks. At 6 weeks, a subset of rats in each group were injected with either saline or ghrelin receptor antagonist, [d-Lys-3] GHRP-6 (DLys; 9 mg/kg body weight) for 5 days and all rats were sacrificed 2 days later. DLys treatment of ethanol rats improved pancreatic insulin secretion, normalized serum insulin levels, and the adipose lipid metabolism, as evidenced by the decreased serum free fatty acids (FFA). DLys treatment of ethanol rats also significantly decreased the circulating FFA uptake, de novo hepatic fatty acid synthesis ultimately attenuating alcoholic steatosis. To summarize, inhibition of ghrelin activity reduced alcoholic steatosis by improving insulin secretion, normalizing serum insulin levels, inhibiting adipose lipolysis, and preventing fatty acid uptake and synthesis in the liver. Our studies provided new insights on the important role of ghrelin in modulating the pancreas-adipose-liver, and promoting adipocyte lipolysis and hepatic steatosis. The findings offer a therapeutic approach of not only preventing alcoholic liver injury but also treating it.
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Affiliation(s)
- Karuna Rasineni
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Research Service, Veterans' Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
| | - Jacy L Kubik
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Research Service, Veterans' Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
| | - Carol A Casey
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Research Service, Veterans' Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
| | - Kusum K Kharbanda
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
- Research Service, Veterans' Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
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19
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Schulze RJ, Schott MB, Casey CA, Tuma PL, McNiven MA. The cell biology of the hepatocyte: A membrane trafficking machine. J Cell Biol 2019; 218:2096-2112. [PMID: 31201265 PMCID: PMC6605791 DOI: 10.1083/jcb.201903090] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 05/24/2019] [Accepted: 05/28/2019] [Indexed: 12/24/2022] Open
Abstract
The liver performs numerous vital functions, including the detoxification of blood before access to the brain while simultaneously secreting and internalizing scores of proteins and lipids to maintain appropriate blood chemistry. Furthermore, the liver also synthesizes and secretes bile to enable the digestion of food. These diverse attributes are all performed by hepatocytes, the parenchymal cells of the liver. As predicted, these cells possess a remarkably well-developed and complex membrane trafficking machinery that is dedicated to moving specific cargos to their correct cellular locations. Importantly, while most epithelial cells secrete nascent proteins directionally toward a single lumen, the hepatocyte secretes both proteins and bile concomitantly at its basolateral and apical domains, respectively. In this Beyond the Cell review, we will detail these central features of the hepatocyte and highlight how membrane transport processes play a key role in healthy liver function and how they are affected by disease.
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Affiliation(s)
- Ryan J Schulze
- Division of Gastroenterology and Hepatology, Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN
| | - Micah B Schott
- Division of Gastroenterology and Hepatology, Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN
| | - Carol A Casey
- Research Service, Department of Veterans Affairs, Nebraska-Western Iowa Health Care System, Omaha, NE
- Departments of Internal Medicine and Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE
| | | | - Mark A McNiven
- Division of Gastroenterology and Hepatology, Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN
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20
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Abstract
Lipid droplets (LDs) are key sites of neutral lipid storage that can be found in all cells. Metabolic imbalances between the synthesis and degradation of LDs can result in the accumulation of significant amounts of lipid deposition, a characteristic feature of hepatocytes in patients with fatty liver disease, a leading indication for liver transplant in the United States. In this review, the authors highlight new literature related to the synthesis and autophagic catabolism of LDs, discussing key proteins and machinery involved in these processes. They also discuss recent findings that have revealed novel genetic risk factors associated with LD biology that contribute to lipid retention in the diseased liver.
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Affiliation(s)
- Ryan J. Schulze
- Department of Biochemistry and Molecular Biology and the Center for Digestive Diseases, Mayo Clinic, Rochester, Minnesota
| | - Mark A. McNiven
- Department of Biochemistry and Molecular Biology and the Center for Digestive Diseases, Mayo Clinic, Rochester, Minnesota
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21
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Thomes PG, Rasineni K, Yang L, Donohue TM, Kubik JL, McNiven MA, Casey CA. Ethanol withdrawal mitigates fatty liver by normalizing lipid catabolism. Am J Physiol Gastrointest Liver Physiol 2019; 316:G509-G518. [PMID: 30714813 PMCID: PMC6957361 DOI: 10.1152/ajpgi.00376.2018] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We are investigating the changes in hepatic lipid catabolism that contribute to alcohol-induced fatty liver. Following chronic ethanol (EtOH) exposure, abstinence from alcohol resolves steatosis. Here, we investigated the hepatocellular events that lead to this resolution by quantifying specific catabolic parameters that returned to control levels after EtOH was withdrawn. We hypothesized that, after its chronic consumption, EtOH withdrawal reactivates lipid catabolic processes that restore lipostasis. Male Wistar rats were fed control and EtOH liquid diets for 6 wk. Randomly chosen EtOH-fed rats were then fed control diet for 7 days. Liver triglycerides (TG), lipid peroxides, key markers of fatty acid (FA) metabolism, lipophagy, and autophagy were quantified. Compared with controls, EtOH-fed rats had higher hepatic triglycerides, lipid peroxides, and serum free fatty acids (FFA). The latter findings were associated with higher levels of FA transporters (FATP 2, 4, and 5) but lower quantities of peroxisome proliferator-activated receptor-α (PPAR-α), which governs FA oxidation. EtOH-fed animals also had lower nuclear levels of the autophagy-regulating transcription factor EB (TFEB), associated with lower hepatic lipophagy and autophagy. After EtOH-fed rats were refed control diet for 7 days, their serum FFA levels and those of FATPs fell to control (normal) levels, whereas PPAR-α levels rose to normal. Hepatic TG and malondialdehyde levels in EtOH-withdrawn rats declined to near control levels. EtOH withdrawal restored nuclear TFEB content, hepatic lipophagy, and autophagy activity to control levels. EtOH withdrawal reversed aberrant FA metabolism and restored lysosomal function to promote resolution of alcohol-induced fatty liver. NEW & NOTEWORTHY Here, using an animal model, we show mechanisms of reversal of fatty liver and injury following EtOH withdrawal. Our data indicate that reactivation of autophagy and lysosome function through the restoration of transcription factor EB contribute to reversal of fatty liver and injury following EtOH withdrawal.
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Affiliation(s)
- Paul G. Thomes
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Karuna Rasineni
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | - Li Yang
- 7Departmentof Internal Medicine, Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Terrence M. Donohue
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,3Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska,4Pathology and Microbiology; College of Medicine; University of Nebraska Medical Center, Omaha, Nebraska,5The Center for Environmental Toxicology; College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska
| | - Jacy L. Kubik
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska
| | - Mark A. McNiven
- 6Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Carol A. Casey
- 1The Liver Study Unit, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, Nebraska,2Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska,3Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska
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22
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Zeng H, Guo X, Zhou F, Xiao L, Liu J, Jiang C, Xing M, Yao P. Quercetin alleviates ethanol-induced liver steatosis associated with improvement of lipophagy. Food Chem Toxicol 2018; 125:21-28. [PMID: 30580029 DOI: 10.1016/j.fct.2018.12.028] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/06/2018] [Accepted: 12/18/2018] [Indexed: 02/07/2023]
Abstract
Although emerging evidence demonstrated that quercetin could be explored as a potential candidate for the early intervention of alcoholic liver disease (ALD), the exact mechanisms against ethanol-induced hepatic steatosis haven't been fully elucidated. Herein, we investigated the effect of quercetin on liver steatosis caused by chronic-plus-single-binge ethanol feeding, focusing on lipophagy. Adult male mice were pair-fed with liquid diets containing ethanol (28% of total calories) and treated with quercetin for 12 weeks. Chronic-plus-binge ethanol consumption led to lipid droplets accumulation and liver damage as evidenced by histopathological changes, the increased content of triglyceride in serum and liver, and the elevated of serum ALT and AST level, which were greatly attenuated by quercetin. Moreover, quercetin blocked autophagy suppression by chronic-binge ethanol intake as manifested by the morphological improvement of mitochondrial characteristics, the increased number of autolysosome and restoration of autophagy-related protein expression. Furthermore, quercetin promoted lipophagy confirmed by the decreased perilipin 2 (PLIN2) level, activated AMPK activity and increased co-localization of liver LC3II and PLIN2 proteins. Collectively, these findings suggest that regular consumption of dietary quercetin has a role in preventing hepatic steatosis induced by chronic-plus-binge ethanol feeding, which mechanism may associate with the evident regulatory effect of quercetin on lipophagy.
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Affiliation(s)
- Hongmei Zeng
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Xiaoping Guo
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Feng Zhou
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Lin Xiao
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Jingjing Liu
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Chunjie Jiang
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Mingyou Xing
- Department of Infectious Disease, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
| | - Ping Yao
- Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China; Ministry of Education Key Laboratory of Environment, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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23
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Listenberger L, Townsend E, Rickertsen C, Hains A, Brown E, Inwards EG, Stoeckman AK, Matis MP, Sampathkumar RS, Osna NA, Kharbanda KK. Decreasing Phosphatidylcholine on the Surface of the Lipid Droplet Correlates with Altered Protein Binding and Steatosis. Cells 2018; 7:cells7120230. [PMID: 30477200 PMCID: PMC6316228 DOI: 10.3390/cells7120230] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 11/19/2018] [Accepted: 11/22/2018] [Indexed: 02/05/2023] Open
Abstract
Alcoholic fatty liver disease (AFLD) is characterized by an abnormal accumulation of lipid droplets (LDs) in the liver. Here, we explore the composition of hepatic LDs in a rat model of AFLD. Five to seven weeks of alcohol consumption led to significant increases in hepatic triglyceride mass, along with increases in LD number and size. Additionally, hepatic LDs from rats with early alcoholic liver injury show a decreased ratio of surface phosphatidylcholine (PC) to phosphatidylethanolamine (PE). This occurred in parallel with an increase in the LD association of perilipin 2, a prominent LD protein. To determine if changes to the LD phospholipid composition contributed to differences in protein association with LDs, we constructed liposomes that modeled the LD PC:PE ratios in AFLD and control rats. Reducing the ratio of PC to PE increased the binding of perilipin 2 to liposomes in an in vitro experiment. Moreover, we decreased the ratio of LD PC:PE in NIH 3T3 and AML12 cells by culturing these cells in choline-deficient media. We again detected increased association of specific LD proteins, including perilipin 2. Taken together, our experiments suggest an important link between LD phospholipids, protein composition, and lipid accumulation.
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Affiliation(s)
- Laura Listenberger
- Departments of Biology and Chemistry, St. Olaf College, Northfield, MN 55057, USA.
| | - Elizabeth Townsend
- Departments of Biology and Chemistry, St. Olaf College, Northfield, MN 55057, USA.
| | - Cassandra Rickertsen
- Departments of Biology and Chemistry, St. Olaf College, Northfield, MN 55057, USA.
| | - Anastasia Hains
- Departments of Biology and Chemistry, St. Olaf College, Northfield, MN 55057, USA.
| | - Elizabeth Brown
- Departments of Biology and Chemistry, St. Olaf College, Northfield, MN 55057, USA.
| | - Emily G Inwards
- Department of Chemistry, Bethel University, St. Paul, MN 55112, USA.
| | | | - Mitchell P Matis
- Research Service, VA Nebraska-Western Iowa Health Care System, Omaha, NE and Departments of Internal Medicine and Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68105, USA.
| | - Rebecca S Sampathkumar
- Research Service, VA Nebraska-Western Iowa Health Care System, Omaha, NE and Departments of Internal Medicine and Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68105, USA.
| | - Natalia A Osna
- Research Service, VA Nebraska-Western Iowa Health Care System, Omaha, NE and Departments of Internal Medicine and Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68105, USA.
| | - Kusum K Kharbanda
- Research Service, VA Nebraska-Western Iowa Health Care System, Omaha, NE and Departments of Internal Medicine and Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68105, USA.
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24
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Tang Q, Jiang S, Jia W, Shen D, Qiu Y, Zhao Y, Xue B, Li C. Zoledronic acid, an FPPS inhibitor, ameliorates liver steatosis through inhibiting hepatic de novo lipogenesis. Eur J Pharmacol 2017; 814:169-177. [PMID: 28843826 DOI: 10.1016/j.ejphar.2017.08.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 08/09/2017] [Accepted: 08/09/2017] [Indexed: 02/07/2023]
Abstract
Currently, there is no standard therapy for non-alcoholic fatty liver disease (NAFLD), and statins have been developed as a first-line pharmaceutical therapeutic option for NAFLD-associated dyslipidemia. However, prolonged statins therapy has side effects, as statins inhibit HMG-CoA reductase, an enzyme at the very beginning of the mevalonate pathway. Here, we found that zoledronic acid (ZA), an inhibitor of farnesyl diphosphate synthase in the downstream mevalonate pathway, could attenuate hepatic lipid accumulation and improve liver injury in both high-fat diet-induced C57BL/6J mice and ob/ob mice. Moreover, the hepatic lipid metabolism was largely inhibited after ZA administration in high-fat diet-induced obese mice. Mechanically, ZA inhibited SREBP-1c-mediated de novo lipogenesis through suppressing RhoA activation via decreasing farnesyl diphosphate and geranylgeranyl diphosphate levels. In conclusion, our data provide a novel application of ZA in improving hepatic steatosis.
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Affiliation(s)
- Qiaoli Tang
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China
| | - Shan Jiang
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China; Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center and Nanjing University, Nanjing 210093, People's Republic of China
| | - Wenjun Jia
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China; Department of Hepatopancreatobiliary Surgery, The Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing 210008, People's Republic of China
| | - Di Shen
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China
| | - Yudong Qiu
- Department of Hepatopancreatobiliary Surgery, The Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing 210008, People's Republic of China
| | - Yue Zhao
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China.
| | - Bin Xue
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China.
| | - Chaojun Li
- School of Medicine of Nanjing University, Nanjing 210093, People's Republic of China; Ministry of Education Key Laboratory of Model Animal for Disease Study, Model Animal Research Center and Nanjing University, Nanjing 210093, People's Republic of China.
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25
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Rasineni K, Donohue TM, Thomes PG, Yang L, Tuma DJ, McNiven MA, Casey CA. Ethanol-induced steatosis involves impairment of lipophagy, associated with reduced Dynamin2 activity. Hepatol Commun 2017; 1:501-512. [PMID: 29152606 PMCID: PMC5678901 DOI: 10.1002/hep4.1063] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 05/11/2017] [Accepted: 05/17/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Lipid droplets (LDs), the organelles central to alcoholic steatosis, are broken down by lipophagy, a specialized form of autophagy. Here, we hypothesize that ethanol administration retards lipophagy by down-regulating Dynamin 2 (Dyn2), a protein that facilitates lysosome re-formation, contributing to hepatocellular steatosis. METHODS Primary hepatocytes were isolated from male Wistar rats fed Lieber-DeCarli control or EtOH liquid diets for 6-8 wk. Hepatocytes were incubated in complete medium (fed) or nutrient-free medium (fasting) with or without the Dyn2 inhibitor Dynasore or the Src inhibitor SU6656. Phosphorylated (active) forms of Src and Dyn2, and markers of autophagy were quantified by Western Blot. Co-localization of LDs-with autophagic machinery was determined by confocal microscopy. RESULTS In hepatocytes from pair-fed rats, LD breakdown was accelerated during fasting, as judged by smaller LDs and lower TG content when compared to hepatocytes in complete media. Fasting-induced TG loss in control hepatocytes was significantly blocked by either SU6656 or Dynasore. Compared to controls, hepatocytes from EtOH-fed rats had 66% and 40% lower content of pSrc and pDyn2, respectively, coupled with lower rate of fasting-induced TG loss. This slower rate of fasting-induced TG loss was blocked in cells co-incubated with Dynasore. Microscopic examination of EtOH-fed rat hepatocytes revealed increased co-localization of the autophagosome marker LC3 on LDs with a concomitant decrease in lysosome marker LAMP1. Whole livers and LD fractions of EtOH-fed rats exhibited simultaneous increase in LC3II and p62 over that of controls, indicating a block in lipophagy. CONCLUSION Chronic ethanol administration slowed the rate of hepatocyte lipophagy, owing in part to lower levels of phosphorylated Src kinase available to activate its substrate, Dyn2, thereby causing depletion of lysosomes for LD breakdown.
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Affiliation(s)
- Karuna Rasineni
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Terrence M. Donohue
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNE
- Department of Pathology and MicrobiologyCollege of Medicine, University of Nebraska Medical CenterOmahaNE
- Center for Environmental ToxicologyCollege of Public Health, University of Nebraska Medical CenterOmahaNE
| | - Paul G. Thomes
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Li Yang
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Tongji HospitalTongji University School of MedicineShanghaiChina
| | - Dean J. Tuma
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Mark A. McNiven
- Department of Biochemistry and Molecular BiologyMayo Clinic College of MedicineRochesterMN
| | - Carol A. Casey
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNE
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26
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Schott MB, Rasineni K, Weller SG, Schulze RJ, Sletten AC, Casey CA, McNiven MA. β-Adrenergic induction of lipolysis in hepatocytes is inhibited by ethanol exposure. J Biol Chem 2017; 292:11815-11828. [PMID: 28515323 DOI: 10.1074/jbc.m117.777748] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 05/05/2017] [Indexed: 12/21/2022] Open
Abstract
In liver steatosis (i.e. fatty liver), hepatocytes accumulate many large neutral lipid storage organelles known as lipid droplets (LDs). LDs are important in the maintenance of energy homeostasis, but the signaling mechanisms that stimulate LD metabolism in hepatocytes are poorly defined. In adipocytes, catecholamines target the β-adrenergic (β-AR)/cAMP pathway to activate cytosolic lipases and induce their recruitment to the LD surface. Therefore, the goal of this study was to determine whether hepatocytes, like adipocytes, also undergo cAMP-mediated lipolysis in response to β-AR stimulation. Using primary rat hepatocytes and human hepatoma cells, we found that treatment with the β-AR agent isoproterenol caused substantial LD loss via activation of cytosolic lipases adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL). β-Adrenergic stimulation rapidly activated PKA, which led to the phosphorylation of ATGL and HSL and their recruitment to the LD surface. To test whether this β-AR-dependent lipolysis pathway was altered in a model of alcoholic fatty liver, primary hepatocytes from rats fed a 6-week EtOH-containing Lieber-DeCarli diet were treated with cAMP agonists. Compared with controls, EtOH-exposed hepatocytes showed a drastic inhibition in β-AR/cAMP-induced LD breakdown and the phosphorylation of PKA substrates, including HSL. This observation was supported in VA-13 cells, an EtOH-metabolizing human hepatoma cell line, which displayed marked defects in both PKA activation and isoproterenol-induced ATGL translocation to the LD periphery. In summary, these findings suggest that β-AR stimulation mobilizes cytosolic lipases for LD breakdown in hepatocytes, and perturbation of this pathway could be a major consequence of chronic EtOH insult leading to fatty liver.
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Affiliation(s)
- Micah B Schott
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905
| | - Karuna Rasineni
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198
| | - Shaun G Weller
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905
| | - Ryan J Schulze
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905
| | - Arthur C Sletten
- Division of Gastroenterology & Hepatology, Center for Basic Research in Digestive Diseases, Mayo Clinic, Rochester, Minnesota 55905
| | - Carol A Casey
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198; Nebraska Western Iowa Health Care System Research Service, Omaha, Nebraska 68105
| | - Mark A McNiven
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905.
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27
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Schulze RJ, Rasineni K, Weller SG, Schott MB, Schroeder B, Casey CA, McNiven MA. Ethanol exposure inhibits hepatocyte lipophagy by inactivating the small guanosine triphosphatase Rab7. Hepatol Commun 2017; 1:140-152. [PMID: 29404450 PMCID: PMC5721426 DOI: 10.1002/hep4.1021] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 01/29/2017] [Indexed: 12/20/2022] Open
Abstract
Alcohol consumption is a well-established risk factor for the onset and progression of fatty liver disease. An estimated 90% of heavy drinkers are thought to develop significant liver steatosis. For these reasons, an increased understanding of the molecular basis for alcohol-induced hepatic steatosis is important. It has become clear that autophagy, a catabolic process of intracellular degradation and recycling, plays a key role in hepatic lipid metabolism. We have shown that Rab7, a small guanosine triphosphatase known to regulate membrane trafficking, acts as a key orchestrator of hepatocellular lipophagy, a selective form of autophagy in which lipid droplets (LDs) are specifically targeted for turnover by the autophagic machinery. Nutrient starvation results in Rab7 activation on the surface of the LD and lysosomal compartments, resulting in the mobilization of triglycerides stored within the LDs for energy production. Here, we examine whether the steatotic effects of alcohol exposure are a result of perturbations to the Rab7-mediated lipophagic pathway. Rats chronically fed an ethanol-containing diet accumulated significantly higher levels of fat in their hepatocytes. Interestingly, hepatocytes isolated from these ethanol-fed rats contained juxtanuclear lysosomes that exhibited impaired motility. These changes are similar to those we observed in Rab7-depleted hepatocytes. Consistent with these defects in the lysosomal compartment, we observed a marked 80% reduction in Rab7 activity in cultured hepatocytes as well as a complete block in starvation-induced Rab7 activation in primary hepatocytes isolated from chronic ethanol-fed animals. Conclusion: A mechanism is supported whereby ethanol exposure inhibits Rab7 activity, resulting in the impaired transport, targeting, and fusion of the autophagic machinery with LDs, leading to an accumulation of hepatocellular lipids and hepatic steatosis. (Hepatology Communications 2017;1:140-152).
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Affiliation(s)
- Ryan J. Schulze
- Department of Biochemistry and Molecular Biology and the Center for Digestive DiseasesMayo ClinicRochesterMN
| | - Karuna Rasineni
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Shaun G. Weller
- Department of Biochemistry and Molecular Biology and the Center for Digestive DiseasesMayo ClinicRochesterMN
| | - Micah B. Schott
- Department of Biochemistry and Molecular Biology and the Center for Digestive DiseasesMayo ClinicRochesterMN
| | - Barbara Schroeder
- Department of Biochemistry and Molecular Biology and the Center for Digestive DiseasesMayo ClinicRochesterMN
- Present address:
Helmholtz Zentrum München, Institute of Biological and Medical ImagingNeuherbergGermany
| | - Carol A. Casey
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Research Service, VA Nebraska‐Western Iowa Health Care SystemOmahaNE
| | - Mark A. McNiven
- Department of Biochemistry and Molecular Biology and the Center for Digestive DiseasesMayo ClinicRochesterMN
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28
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Natarajan SK, Rasineni K, Ganesan M, Feng D, McVicker BL, McNiven MA, Osna NA, Mott JL, Casey CA, Kharbanda KK. Structure, Function and Metabolism of Hepatic and Adipose Tissue Lipid Droplets: Implications in Alcoholic Liver Disease. Curr Mol Pharmacol 2017; 10:237-248. [PMID: 26278390 PMCID: PMC4820363 DOI: 10.2174/1874467208666150817111727] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 08/07/2015] [Accepted: 08/07/2015] [Indexed: 02/08/2023]
Abstract
For more than 30 years, lipid droplets (LDs) were considered as an inert bag of lipid for storage of energy-rich fat molecules. Following a paradigm shift almost a decade ago, LDs are presently considered an active subcellular organelle especially designed for assembling, storing and subsequently supplying lipids for generating energy and membrane synthesis (and in the case of hepatocytes for VLDL secretion). LDs also play a central role in many other cellular functions such as viral assembly and protein degradation. Here, we have explored the structural and functional changes that occur in hepatic and adipose tissue LDs following chronic ethanol consumption in relation to their role in the pathogenesis of alcoholic liver injury.
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Affiliation(s)
| | - Karuna Rasineni
- Research Service, VA Nebraska-Western Iowa Health Care System (VA NWIHCS). 0
| | - Murali Ganesan
- Research Service, VA Nebraska-Western Iowa Health Care System (VA NWIHCS). 0
| | - Dan Feng
- Research Service, VA Nebraska-Western Iowa Health Care System (VA NWIHCS). 0
| | - Benita L McVicker
- Research Service, VA Nebraska-Western Iowa Health Care System (VA NWIHCS). 0
| | - Mark A McNiven
- Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota. United States
| | - Natalia A Osna
- Research Service, VA Nebraska-Western Iowa Health Care System (VA NWIHCS). 0
| | - Justin L Mott
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center. 0
| | - Carol A Casey
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center. 0
| | - Kusum K Kharbanda
- Veterans Affairs Nebraska Western Iowa Health Care System, Research Service (151), 4101 Woolworth Avenue, Omaha, Nebraska, 68105. United States
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29
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Li C, Yu SSB. Rab proteins as regulators of lipid droplet formation and lipolysis. Cell Biol Int 2016; 40:1026-32. [PMID: 27453349 DOI: 10.1002/cbin.10650] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 07/22/2016] [Indexed: 12/11/2022]
Abstract
Lipid droplets (LDs) are highly dynamic organelles that not only store neutral lipids but also are involved in multiple cellular processes. Dysregulation of lipogenesis or lipolysis greatly contributes to the pathogenesis of several human diseases, including obesity, diabetes, and fatty liver disease. Rab proteins have been found to be associated with LDs in proteomic studies and are also known to extensively regulate intracellular membrane traffic, suggesting that LDs actively communicate with other membrane compartments to maintain energy homeostasis. This review discusses recent studies that provide mechanistic insights into the regulation of LD formation and catabolism by Rab proteins in mammalian cells.
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Affiliation(s)
- Chunman Li
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Sidney S B Yu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China. .,Epithelial Cell Biology Research Centre, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China.
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Alcoholic vs non-alcoholic fatty liver in rats: distinct differences in endocytosis and vesicle trafficking despite similar pathology. BMC Gastroenterol 2016; 16:27. [PMID: 26924554 PMCID: PMC4770635 DOI: 10.1186/s12876-016-0433-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 02/12/2016] [Indexed: 12/13/2022] Open
Abstract
Background Non-alcoholic and alcoholic fatty liver disease (NAFLD and AFLD, respectively) are major health problems, as patients with either condition can progress to hepatitis, fibrosis, and cirrhosis. Although histologically similar, key differences likely exist in these two models. For example, altered content of several vesicle trafficking proteins have been identified in AFLD, but their content in NAFLD is unknown. In this study, we compared select parameters in NAFLD and AFLD in a rat model. Methods We fed either Lieber- DeCarli liquid control or alcohol-containing (35 % as calories) diet (AFLD model) or lean or high-fat (12 or 60 % derived from fat, respectively) pellets (NAFLD model) for 8–10 weeks, n = 8 in each model. Serum, hepatocytes and liver tissue were analyzed. Liver injury markers were measured in serum, triglyceride content and endocytosis (binding and internalization of 125I- asialoorosomucoid) was measured in isolated hepatocytes, and content of selected trafficking proteins (Rab3D, Rab7 and Rab18) were determined in whole liver tissue. Results Although liver injury markers and triglyceride content were similar in both models, binding and internalization of 125I- asialoorosomucoid was significantly impaired in the hepatocytes from AFLD, but not NAFLD, animals. In addition, protein content of the asialoglycoprotein receptor (ASGPR) and three trafficking proteins, Rab3D, Rab7and Rab18, were significantly decreased after alcohol, but not high-fat feeding. Levels of protein carbonylation, amount of glutathione stores, and lipid peroxidation were similar irrespective of the insult to the livers that resulted in fatty liver. Conclusion Impairments in protein trafficking in AFLD are likely a direct result of alcohol administration, and not a function of fatty liver.
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Identification of Host Cell Factors Associated with Astrovirus Replication in Caco-2 Cells. J Virol 2015; 89:10359-70. [PMID: 26246569 DOI: 10.1128/jvi.01225-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 07/28/2015] [Indexed: 01/25/2023] Open
Abstract
UNLABELLED Astroviruses are small, nonenveloped viruses with a single-stranded positive-sense RNA genome causing acute gastroenteritis in children and immunocompromised patients. Since positive-sense RNA viruses have frequently been found to replicate in association with membranous structures, in this work we characterized the replication of the human astrovirus serotype 8 strain Yuc8 in Caco-2 cells, using density gradient centrifugation and free-flow zonal electrophoresis (FFZE) to fractionate cellular membranes. Structural and nonstructural viral proteins, positive- and negative-sense viral RNA, and infectious virus particles were found to be associated with a distinct population of membranes separated by FFZE. The cellular proteins associated with this membrane population in infected and mock-infected cells were identified by tandem mass spectrometry. The results indicated that membranes derived from multiple cell organelles were present in the population. Gene ontology and protein-protein interaction network analysis showed that groups of proteins with roles in fatty acid synthesis and ATP biosynthesis were highly enriched in the fractions of this population in infected cells. Based on this information, we investigated by RNA interference the role that some of the identified proteins might have in the replication cycle of the virus. Silencing of the expression of genes involved in cholesterol (DHCR7, CYP51A1) and fatty acid (FASN) synthesis, phosphatidylinositol (PI4KIIIβ) and inositol phosphate (ITPR3) metabolism, and RNA helicase activity (DDX23) significantly decreased the amounts of Yuc8 genomic and antigenomic RNA, synthesis of the structural protein VP90, and virus yield. These results strongly suggest that astrovirus RNA replication and particle assembly take place in association with modified membranes potentially derived from multiple cell organelles. IMPORTANCE Astroviruses are common etiological agents of acute gastroenteritis in children and immunocompromised patients. More recently, they have been associated with neurological diseases in mammals, including humans, and are also responsible for different pathologies in birds. In this work, we provide evidence that astrovirus RNA replication and virus assembly occur in contact with cell membranes potentially derived from multiple cell organelles and show that membrane-associated cellular proteins involved in lipid metabolism are required for efficient viral replication. Our findings provide information to enhance our knowledge of astrovirus biology and provide information that might be useful for the development of therapeutic interventions to prevent virus replication.
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Ikura Y, Caldwell SH. Lipid droplet-associated proteins in alcoholic liver disease: a potential linkage with hepatocellular damage. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:8699-8708. [PMID: 26464614 PMCID: PMC4583846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 07/29/2015] [Indexed: 06/05/2023]
Abstract
Steatosis is a characteristic morphological change of alcoholic liver disease, but its pathologic significance is still obscure. Regardless of cell types, intracellular lipid droplets are coated with a phospholipid monolayer, on which many kinds of lipid droplet-associated proteins are present. These proteins, such as the perilipin family of proteins and the cell death inducing DNA fragmentation factor (DFF) 45-like effectors, are recognized to play important roles in lipid metabolism in the physiological settings. In addition, recent lipidology studies have revealed that expression of the lipid droplet-associated proteins possibly participate in the pathologic processes of many metabolic disorders, including fatty liver and insulin resistance. Hence, controlling protein expressions is expected to offer novel therapeutic options. In this review, we summarize collected data concerning the potential contribution of the lipid droplet-associated proteins to the development of alcoholic fatty liver. Without exception, existing data indicates that the lipid droplet-associated proteins, especially the perilipin family proteins, are important factors in alcoholic fatty liver. These proteins exert a prosteatotic effect, and their expression is closely associated with lipotoxicity based on endoplasmic reticulum stress and oxidative injury. Although suppression of their expression may be beneficial, careful consideration is required because these proteins simultaneously function as protective factors against lipotoxicity.
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Affiliation(s)
- Yoshihiro Ikura
- Department of Pathology, Takatsuki General Hospital1-3-13, Kosobecho, Takatsuki 569-1192, Japan
| | - Stephen H Caldwell
- Division of Gastroenterology and Hepatology, University of VirginiaCharlottesville, Virginia 22908-0708, USA
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Wandinger-Ness A, Zerial M. Rab proteins and the compartmentalization of the endosomal system. Cold Spring Harb Perspect Biol 2014; 6:a022616. [PMID: 25341920 PMCID: PMC4413231 DOI: 10.1101/cshperspect.a022616;] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Of the approximately 70 human Rab GTPases, nearly three-quarters are involved in endocytic trafficking. Significant plasticity in endosomal membrane transport pathways is closely coupled to receptor signaling and Rab GTPase-regulated scaffolds. Here we review current literature pertaining to endocytic Rab GTPase localizations, functions, and coordination with regulatory proteins and effectors. The roles of Rab GTPases in (1) compartmentalization of the endocytic pathway into early, recycling, late, and lysosomal routes; (2) coordination of individual transport steps from vesicle budding to fusion; (3) effector interactomes; and (4) integration of GTPase and signaling cascades are discussed.
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Affiliation(s)
- Angela Wandinger-Ness
- Department of Pathology MSC08 4640, University of New Mexico HSC, Albuquerque, New Mexico 87131
| | - Marino Zerial
- Max Planck Institute of Molecular and Cell Biology and Genetics, 01307 Dresden, Germany
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Wandinger-Ness A, Zerial M. Rab proteins and the compartmentalization of the endosomal system. Cold Spring Harb Perspect Biol 2014; 6:a022616. [PMID: 25341920 DOI: 10.1101/cshperspect.a022616] [Citation(s) in RCA: 414] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Of the approximately 70 human Rab GTPases, nearly three-quarters are involved in endocytic trafficking. Significant plasticity in endosomal membrane transport pathways is closely coupled to receptor signaling and Rab GTPase-regulated scaffolds. Here we review current literature pertaining to endocytic Rab GTPase localizations, functions, and coordination with regulatory proteins and effectors. The roles of Rab GTPases in (1) compartmentalization of the endocytic pathway into early, recycling, late, and lysosomal routes; (2) coordination of individual transport steps from vesicle budding to fusion; (3) effector interactomes; and (4) integration of GTPase and signaling cascades are discussed.
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Affiliation(s)
- Angela Wandinger-Ness
- Department of Pathology MSC08 4640, University of New Mexico HSC, Albuquerque, New Mexico 87131
| | - Marino Zerial
- Max Planck Institute of Molecular and Cell Biology and Genetics, 01307 Dresden, Germany
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Kiss RS, Nilsson T. Rab proteins implicated in lipid storage and mobilization. J Biomed Res 2014; 28:169-77. [PMID: 25013400 PMCID: PMC4085554 DOI: 10.7555/jbr.28.20140029] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 02/28/2014] [Indexed: 12/28/2022] Open
Abstract
Abnormal intracellular accumulation or transport of lipids contributes greatly to the pathogenesis of human diseases. In the liver, excess accumulation of triacylglycerol (TG) leads to fatty liver disease encompassing steatosis, steatohepatitis and fibrosis. This places individuals at risk of developing cirrhosis, hepatocellular carcinoma or hepatic decompensation and also contributes to the emergence of insulin resistance and dyslipidemias affecting many other organs. Excessive accumulation of TG in adipose tissue contributes to insulin resistance as well as to the release of cytokines attracting leucocytes leading to a pro-inflammatory state. Pathological accumulation of cholesteryl ester (CE) in macrophages in the arterial wall is the progenitor of atherosclerotic plaques and heart disease. Overconsumption of dietary fat, cholesterol and carbohydrates explains why these diseases are on the increase yet offers few clues for how to prevent or treat individuals. Dietary regimes have proven futile and barring surgery, no realistic alternatives are at hand as effective drugs are few and not without side effects. Overweight and obesity-related diseases are no longer restricted to the developed world and as such, constitute a global problem. Development of new drugs and treatment strategies are a priority yet requires as a first step, elucidation of the molecular pathophysiology underlying each associated disease state. The lipid droplet (LD), an up to now overlooked intracellular organelle, appears at the heart of each pathophysiology linking key regulatory and metabolic processes as well as constituting the site of storage of both TGs and CEs. As the molecular machinery and mechanisms of LDs of each cell type are being elucidated, regulatory proteins used to control various cellular processes are emerging. Of these and the subject of this review, small GTPases belonging to the Rab protein family appear as important molecular switches used in the regulation of the intracellular trafficking and storage of lipids.
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Affiliation(s)
- Robert Scott Kiss
- Department of Medicine, McGill University, Montreal, Canada; ; Research Institute of McGill University Health Centre, Montreal, Canada
| | - Tommy Nilsson
- Department of Medicine, McGill University, Montreal, Canada; ; Research Institute of McGill University Health Centre, Montreal, Canada
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