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Xu L, Li L, Wu L, Li P, Chen FJ. CIDE proteins and their regulatory mechanisms in lipid droplet fusion and growth. FEBS Lett 2024; 598:1154-1169. [PMID: 38355218 DOI: 10.1002/1873-3468.14823] [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: 10/28/2023] [Revised: 12/19/2023] [Accepted: 01/04/2024] [Indexed: 02/16/2024]
Abstract
The cell death-inducing DFF45-like effector (CIDE) proteins, including Cidea, Cideb, and Cidec/Fsp27, regulate various aspects of lipid homeostasis, including lipid storage, lipolysis, and lipid secretion. This review focuses on the physiological roles of CIDE proteins based on studies on knockout mouse models and human patients bearing CIDE mutations. The primary cellular function of CIDE proteins is to localize to lipid droplets (LDs) and to control LD fusion and growth across different cell types. We propose a four-step process of LD fusion, characterized by (a) the recruitment of CIDE proteins to the LD surface and CIDE movement, (b) the enrichment and condensate formation of CIDE proteins to form LD fusion plates at LD-LD contact sites, (c) lipid transfer through lipid-permeable passageways within the fusion plates, and (d) the completion of LD fusion. Lastly, we outline CIDE-interacting proteins as regulatory factors, as well as their contribution in LD fusion.
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Affiliation(s)
- Li Xu
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lizhen Li
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lingzhi Wu
- College of Future Technology, Peking University, Beijing, China
| | - Peng Li
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China
- Tianjian Laboratory of Advanced Biomedical Sciences, Zhengzhou University, China
| | - Feng-Jung Chen
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China
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2
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Griseti E, Bello AA, Bieth E, Sabbagh B, Iacovoni JS, Bigay J, Laurell H, Čopič A. Molecular mechanisms of perilipin protein function in lipid droplet metabolism. FEBS Lett 2024; 598:1170-1198. [PMID: 38140813 DOI: 10.1002/1873-3468.14792] [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: 10/21/2023] [Revised: 11/27/2023] [Accepted: 12/11/2023] [Indexed: 12/24/2023]
Abstract
Perilipins are abundant lipid droplet (LD) proteins present in all metazoans and also in Amoebozoa and fungi. Humans express five perilipins, which share a similar domain organization: an amino-terminal PAT domain and an 11-mer repeat region, which can fold into amphipathic helices that interact with LDs, followed by a structured carboxy-terminal domain. Variations of this organization that arose during vertebrate evolution allow for functional specialization between perilipins in relation to the metabolic needs of different tissues. We discuss how different features of perilipins influence their interaction with LDs and their cellular targeting. PLIN1 and PLIN5 play a direct role in lipolysis by regulating the recruitment of lipases to LDs and LD interaction with mitochondria. Other perilipins, particularly PLIN2, appear to protect LDs from lipolysis, but the molecular mechanism is not clear. PLIN4 stands out with its long repetitive region, whereas PLIN3 is most widely expressed and is used as a nascent LD marker. Finally, we discuss the genetic variability in perilipins in connection with metabolic disease, prominent for PLIN1 and PLIN4, underlying the importance of understanding the molecular function of perilipins.
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Affiliation(s)
- Elena Griseti
- Institut des Maladies Métaboliques et Cardiovasculaires - I2MC, Université de Toulouse, Inserm, Université Toulouse III - Paul Sabatier (UPS), France
| | - Abdoul Akim Bello
- Institut de Pharmacologie Moléculaire et Cellulaire - IPMC, Université Côte d'Azur, CNRS, Valbonne, France
| | - Eric Bieth
- Institut des Maladies Métaboliques et Cardiovasculaires - I2MC, Université de Toulouse, Inserm, Université Toulouse III - Paul Sabatier (UPS), France
- Departement de Génétique Médicale, Centre Hospitalier Universitaire de Toulouse, France
| | - Bayane Sabbagh
- Centre de Recherche en Biologie Cellulaire de Montpellier - CRBM, Université de Montpellier, CNRS, France
| | - Jason S Iacovoni
- Institut des Maladies Métaboliques et Cardiovasculaires - I2MC, Université de Toulouse, Inserm, Université Toulouse III - Paul Sabatier (UPS), France
| | - Joëlle Bigay
- Institut de Pharmacologie Moléculaire et Cellulaire - IPMC, Université Côte d'Azur, CNRS, Valbonne, France
| | - Henrik Laurell
- Institut des Maladies Métaboliques et Cardiovasculaires - I2MC, Université de Toulouse, Inserm, Université Toulouse III - Paul Sabatier (UPS), France
| | - Alenka Čopič
- Centre de Recherche en Biologie Cellulaire de Montpellier - CRBM, Université de Montpellier, CNRS, France
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N-Octyl Caffeamide, a Caffeic Acid Amide Derivative, Prevents Progression of Diabetes and Hepatic Steatosis in High-Fat Diet Induced Obese Mice. Int J Mol Sci 2022; 23:ijms23168948. [PMID: 36012215 PMCID: PMC9409300 DOI: 10.3390/ijms23168948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 11/30/2022] Open
Abstract
The underlying pathological mechanisms of diabetes are complicated and varied in diabetic patients, which may lead to the current medications often failing to maintain glycemic control in the long term. Thus, the discovery of diverse new compounds for developing medicines to treat diabetes and its complications are urgently needed. Polyphenols are metabolites of plants and have been employed in the prevention and treatment of a variety of diseases. Caffeic acid phenethyl ester (CAPE) is a category of compounds structurally similar to polyphenols. In this study, we aimed to investigate the antidiabetic activity and potential molecular mechanisms of a novel synthetic CAPE derivative N-octyl caffeamide (36M) using high-fat (HF) diet induced obese mouse models. Our results demonstrate that 36M prevented the progression of diabetes in the HF diet fed obese mice via increasing phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) and inhibiting expression of protein tyrosine phosphatase 1B (PTP1B). We also found that 36M could prevent hepatic lipid storage in the HF diet fed mice via inhibition of fatty acid synthase and lipid droplet proteins, including perilipins and Fsp27. In conclusion, 36M is a potential candidate compound that can be developed as AMPK inhibitor and PTP1B inhibitor for treating diabetes and hepatic steatosis.
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Tang XH, Melis M, Lu C, Rappa A, Zhang T, Jessurun J, Gross SS, Gudas LJ. A retinoic acid receptor β2 agonist attenuates transcriptome and metabolome changes underlying nonalcohol-associated fatty liver disease. J Biol Chem 2021; 297:101331. [PMID: 34688661 PMCID: PMC8626588 DOI: 10.1016/j.jbc.2021.101331] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/12/2021] [Accepted: 10/19/2021] [Indexed: 12/12/2022] Open
Abstract
Nonalcohol-associated fatty liver disease (NAFLD) is characterized by excessive hepatic accumulation of fat that can progress to steatohepatitis, and currently, therapeutic options are limited. Using a high-fat diet (HFD) mouse model of NAFLD, we determined the effects of the synthetic retinoid, AC261066, a selective retinoic acid receptor β2 (RARβ2) agonist, on the global liver transcriptomes and metabolomes of mice with dietary-induced obesity (DIO) using genome-wide RNA-seq and untargeted metabolomics. We found that AC261066 limits mRNA increases in several presumptive NAFLD driver genes, including Pklr, Fasn, Thrsp, and Chchd6. Importantly, AC261066 limits the increases in the transcript and protein levels of KHK, a key enzyme for fructose metabolism, and causes multiple changes in liver metabolites involved in fructose metabolism. In addition, in cultured murine hepatocytes, where exposure to fructose and palmitate results in a profound increase in lipid accumulation, AC261066 limits this lipid accumulation. Importantly, we demonstrate that in a human hepatocyte cell line, RARβ is required for the inhibitory effects of AC261066 on palmitate-induced lipid accumulation. Finally, our data indicate that AC261066 inhibits molecular events underpinning fibrosis and exhibits anti-inflammatory effects. In conclusion, changes in the transcriptome and metabolome indicate that AC261066 affects molecular changes underlying multiple aspects of NAFLD, including steatosis and fibrosis. Therefore, we suggest that AC261066 may have potential as an effective therapy for NAFLD.
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Affiliation(s)
- Xiao-Han Tang
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Marta Melis
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Changyuan Lu
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Andrew Rappa
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Tuo Zhang
- Genomics Resources Core Facility, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Jose Jessurun
- Division of Anatomic Pathology, Department of Pathology and Laboratory Medicine, New York Presbyterian Hospital, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Steven S Gross
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA
| | - Lorraine J Gudas
- Department of Pharmacology, Weill Cornell Medical College of Cornell University, New York, New York, USA.
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Fatty Acid-Binding Protein 1 as a Potential New Serological Marker of Liver Status in Children With Wilson Disease. J Pediatr Gastroenterol Nutr 2021; 73:455-462. [PMID: 33908738 DOI: 10.1097/mpg.0000000000003128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES Wilson disease (WD) is a copper metabolism disorder with toxic copper accumulation in the liver leading to liver steatosis or fibrosis. In vitro studies suggest that fatty acid-binding protein 1 (L-FABP) and lipid droplet-associated protein 5 (PLIN5) may have an impact on both processes, but knowledge about these potential biomarkers is insufficient in the case of WD. Thus, the aim of this study was to determine L-FABP and PLIN5 levels in sera of WD patients in relation to liver steatosis/fibrosis. METHODS The final study involved 74 WD children in whom liver steatosis (WD1 subgroup, n = 28) and fibrosis (WD2 subgroup, n = 13) were assessed with the use of transient elastography. Control groups included WD children without steatosis and fibrosis (WD0 subgroup, n = 33) and healthy children (n = 75). L-FABP and PLIN5 measurements were performed in sera with the use of the immunoenzymatic method. RESULTS L-FABP was significantly higher in the WD2 subgroup, and the correlation between L-FABP concentration and liver fibrosis was confirmed statistically by regression analysis (P = 0.04) with Pearson's coefficient r = 0.24. L-FABP was significantly correlated with alanine aminotransferase (r = 0.42) and aspartate aminotransferase (r = 0.37) activity. PLIN5 concentration was similar in all groups and was not related to steatosis and fibrosis. CONCLUSIONS Our results suggest that serum L-FABP could be a novel biomarker of liver fibrosis in WD children.
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Shi Y, Pizzini J, Wang H, Das F, Abdul Azees PA, Ghosh Choudhury G, Barnes JL, Zang M, Weintraub ST, Yeh CK, Katz MS, Kamat A. β2-Adrenergic receptor agonist induced hepatic steatosis in mice: modeling nonalcoholic fatty liver disease in hyperadrenergic states. Am J Physiol Endocrinol Metab 2021; 321:E90-E104. [PMID: 34029162 PMCID: PMC8321826 DOI: 10.1152/ajpendo.00651.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 04/23/2021] [Accepted: 05/08/2021] [Indexed: 12/11/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) is a spectrum of disorders ranging from hepatic steatosis [excessive accumulation of triglycerides (TG)] to nonalcoholic steatohepatitis, which can progress to cirrhosis and hepatocellular carcinoma. The molecular pathogenesis of steatosis and progression to more severe NAFLD remains unclear. Obesity and aging, two principal risk factors for NAFLD, are associated with a hyperadrenergic state. β-Adrenergic responsiveness in liver increases in animal models of obesity and aging, and in both is linked to increased hepatic expression of β2-adrenergic receptors (β2-ARs). We previously showed that in aging rodents intracellular signaling from elevated hepatic levels of β2-ARs may contribute to liver steatosis. In this study we demonstrate that injection of formoterol, a highly selective β2-AR agonist, to mice acutely results in hepatic TG accumulation. Further, we have sought to define the intrahepatic mechanisms underlying β2-AR mediated steatosis by investigating changes in hepatic expression and cellular localization of enzymes, transcription factors, and coactivators involved in processes of lipid accrual and disposition-and also functional aspects thereof-in livers of formoterol-treated animals. Our results suggest that β2-AR activation by formoterol leads to increased hepatic TG synthesis and de novo lipogenesis, increased but incomplete β-oxidation of fatty acids with accumulation of potentially toxic long-chain acylcarnitine intermediates, and reduced TG secretion-all previously invoked as contributors to fatty liver disease. Experiments are ongoing to determine whether sustained activation of hepatic β2-AR signaling by formoterol might be utilized to model fatty liver changes occurring in hyperadrenergic states of obesity and aging, and thereby identify novel molecular targets for the prevention or treatment of NAFLD.NEW & NOTEWORTHY Results of our study suggest that β2-adrenergic receptor (β2-AR) activation by agonist formoterol leads to increased hepatic TG synthesis and de novo lipogenesis, incomplete β-oxidation of fatty acids with accumulation of long-chain acylcarnitine intermediates, and reduced TG secretion. These findings may, for the first time, implicate a role for β2-AR responsive dysregulation of hepatic lipid metabolism in the pathogenetic processes underlying NAFLD in hyperadrenergic states such as obesity and aging.
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Affiliation(s)
- Yun Shi
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Jason Pizzini
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Hanzhou Wang
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Falguni Das
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Parveez Ahamed Abdul Azees
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Goutam Ghosh Choudhury
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Jeffrey L Barnes
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Mengwei Zang
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, Texas
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, Texas
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, Texas
| | - Susan T Weintraub
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Chih-Ko Yeh
- Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, Texas
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, Texas
| | - Michael S Katz
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, Texas
| | - Amrita Kamat
- Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
- Barshop Institute for Longevity and Aging Studies, University of Texas Health Science Center at San Antonio, San Antonio, Texas
- Geriatric Research, Education and Clinical Center, Audie L. Murphy Division, South Texas Veterans Health Care System, San Antonio, Texas
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Friend or Foe: Lipid Droplets as Organelles for Protein and Lipid Storage in Cellular Stress Response, Aging and Disease. Molecules 2020; 25:molecules25215053. [PMID: 33143278 PMCID: PMC7663626 DOI: 10.3390/molecules25215053] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 02/06/2023] Open
Abstract
Lipid droplets (LDs) were considered as a mere lipid storage organelle for a long time. Recent evidence suggests that LDs are in fact distinct and dynamic organelles with a specialized proteome and functions in many cellular roles. As such, LDs contribute to cellular signaling, protein and lipid homeostasis, metabolic diseases and inflammation. In line with the multitude of functions, LDs interact with many cellular organelles including mitochondria, peroxisomes, lysosomes, the endoplasmic reticulum and the nucleus. LDs are highly mobile and dynamic organelles and impaired motility disrupts the interaction with other organelles. The reduction of interorganelle contacts results in a multitude of pathophysiologies and frequently in neurodegenerative diseases. Contacts not only supply lipids for β-oxidation in mitochondria and peroxisomes, but also may include the transfer of toxic lipids as well as misfolded and harmful proteins to LDs. Furthermore, LDs assist in the removal of protein aggregates when severe proteotoxic stress overwhelms the proteasomal system. During imbalance of cellular lipid homeostasis, LDs also support cellular detoxification. Fine-tuning of LD function is of crucial importance and many diseases are associated with dysfunctional LDs. We summarize the current understanding of LDs and their interactions with organelles, providing a storage site for harmful proteins and lipids during cellular stress, aging inflammation and various disease states.
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Okuyama T, Shirakawa J, Tajima K, Ino Y, Vethe H, Togashi Y, Kyohara M, Inoue R, Miyashita D, Li J, Goto N, Ichikawa T, Yamasaki S, Ohnuma H, Takayanagi R, Kimura Y, Hirano H, Terauchi Y. Linagliptin Ameliorates Hepatic Steatosis via Non-Canonical Mechanisms in Mice Treated with a Dual Inhibitor of Insulin Receptor and IGF-1 Receptor. Int J Mol Sci 2020; 21:ijms21217815. [PMID: 33105604 PMCID: PMC7672621 DOI: 10.3390/ijms21217815] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 10/19/2020] [Accepted: 10/19/2020] [Indexed: 12/21/2022] Open
Abstract
Abnormal hepatic insulin signaling is a cause or consequence of hepatic steatosis. DPP-4 inhibitors might be protective against fatty liver. We previously reported that the systemic inhibition of insulin receptor (IR) and IGF-1 receptor (IGF1R) by the administration of OSI-906 (linsitinib), a dual IR/IGF1R inhibitor, induced glucose intolerance, hepatic steatosis, and lipoatrophy in mice. In the present study, we investigated the effects of a DPP-4 inhibitor, linagliptin, on hepatic steatosis in OSI-906-treated mice. Unlike high-fat diet-induced hepatic steatosis, OSI-906-induced hepatic steatosis is not characterized by elevations in inflammatory responses or oxidative stress levels. Linagliptin improved OSI-906-induced hepatic steatosis via an insulin-signaling-independent pathway, without altering glucose levels, free fatty acid levels, gluconeogenic gene expressions in the liver, or visceral fat atrophy. Hepatic quantitative proteomic and phosphoproteomic analyses revealed that perilipin-2 (PLIN2), major urinary protein 20 (MUP20), cytochrome P450 2b10 (CYP2B10), and nicotinamide N-methyltransferase (NNMT) are possibly involved in the process of the amelioration of hepatic steatosis by linagliptin. Thus, linagliptin improved hepatic steatosis induced by IR and IGF1R inhibition via a previously unknown mechanism that did not involve gluconeogenesis, lipogenesis, or inflammation, suggesting the non-canonical actions of DPP-4 inhibitors in the treatment of hepatic steatosis under insulin-resistant conditions.
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Affiliation(s)
- Tomoko Okuyama
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Jun Shirakawa
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
- Laboratory and Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8510, Japan
- Correspondence: ; Tel.: +81-27-220-8850
| | - Kazuki Tajima
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Yoko Ino
- Advanced Medical Research Center, Yokohama City University, Yokohama 236-0004, Japan; (Y.I.); (Y.K.)
| | - Heidrun Vethe
- Department of Clinical Medicine, University of Bergen, P.O. Box 7803 Bergen, Norway;
| | - Yu Togashi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Mayu Kyohara
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Ryota Inoue
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
- Laboratory and Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8510, Japan
| | - Daisuke Miyashita
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Jinghe Li
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
- Laboratory and Diabetes and Metabolic Disorders, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8510, Japan
| | - Nozomi Goto
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Taiga Ichikawa
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Shingo Yamasaki
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Haruka Ohnuma
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Rie Takayanagi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
| | - Yayoi Kimura
- Advanced Medical Research Center, Yokohama City University, Yokohama 236-0004, Japan; (Y.I.); (Y.K.)
| | - Hisashi Hirano
- Graduate School of Health Science, Gunma Paz University, Takasaki 370-0006, Japan;
| | - Yasuo Terauchi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama 236-0004, Japan; (T.O.); (K.T.); (Y.T.); (M.K.); (R.I.); (D.M.); (J.L.); (N.G.); (T.I.); (S.Y.); (H.O.); (R.T.); (Y.T.)
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9
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Lutkewitte AJ, Finck BN. Regulation of Signaling and Metabolism by Lipin-mediated Phosphatidic Acid Phosphohydrolase Activity. Biomolecules 2020; 10:E1386. [PMID: 33003344 PMCID: PMC7600782 DOI: 10.3390/biom10101386] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 09/23/2020] [Accepted: 09/24/2020] [Indexed: 12/15/2022] Open
Abstract
Phosphatidic acid (PA) is a glycerophospholipid intermediate in the triglyceride synthesis pathway that has incredibly important structural functions as a component of cell membranes and dynamic effects on intracellular and intercellular signaling pathways. Although there are many pathways to synthesize and degrade PA, a family of PA phosphohydrolases (lipin family proteins) that generate diacylglycerol constitute the primary pathway for PA incorporation into triglycerides. Previously, it was believed that the pool of PA used to synthesize triglyceride was distinct, compartmentalized, and did not widely intersect with signaling pathways. However, we now know that modulating the activity of lipin 1 has profound effects on signaling in a variety of cell types. Indeed, in most tissues except adipose tissue, lipin-mediated PA phosphohydrolase activity is far from limiting for normal rates of triglyceride synthesis, but rather impacts critical signaling cascades that control cellular homeostasis. In this review, we will discuss how lipin-mediated control of PA concentrations regulates metabolism and signaling in mammalian organisms.
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Affiliation(s)
| | - Brian N. Finck
- Center for Human Nutrition, Division of Geriatrics and Nutritional Sciences, Department of Medicine, Washington University School of Medicine, Euclid Avenue, Campus Box 8031, St. Louis, MO 63110, USA;
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Arumugam MK, Talawar S, Listenberger L, Donohue TM, Osna NA, Kharbanda KK. Role of Elevated Intracellular S-Adenosylhomocysteine in the Pathogenesis of Alcohol-Related Liver Disease. Cells 2020; 9:cells9061526. [PMID: 32585865 PMCID: PMC7349643 DOI: 10.3390/cells9061526] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 06/19/2020] [Accepted: 06/21/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND The earliest manifestation of alcohol-related liver disease (ALD) is steatosis, characterized by the accumulation of lipid droplets (LDs) in hepatocytes. Findings from our laboratory have indicated that many pathological changes, including steatosis, correlate with the alcohol-induced hepatocellular increases in S-adenosylhomocysteine (SAH). Based on these considerations, we hypothesized that an experimental increase in intracellular SAH alone will result in similar steatotic changes to those seen after alcohol exposure. METHODS Freshly isolated rat hepatocytes grown on collagen-coated plates were exposed to serum-free medium containing 50 µmol/L oleic acid and varying concentrations of 3-deazaadenosine (DZA) to experimentally elevate intracellular SAH levels. RESULTS Overnight exposure to DZA treatment dose-dependently increased hepatocellular triglyceride accumulation, which was also evident by morphological visualization of larger-sized LDs. The rise in triglycerides and LDs accompanied increases in mRNA and protein levels of several LD-associated proteins known to regulate LD number and size. Furthermore, DZA treatment caused a decline in the levels of lipases that prevent fat accumulation as well as increased the expression of factors involved in lipogenesis and fatty acid mobilization. Collectively, our results indicate that the elevation of intracellular SAH is sufficient to promote fat accumulation in hepatocytes, which is similar to that seen after alcohol exposure.
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Affiliation(s)
- Madan Kumar Arumugam
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA; (M.K.A.); (S.T.); (T.M.D.J.); (N.A.O.)
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Sharanappa Talawar
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA; (M.K.A.); (S.T.); (T.M.D.J.); (N.A.O.)
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Laura Listenberger
- Departments of Biology and Chemistry, St. Olaf College, Northfield, MN 55057, USA;
| | - Terrence M. Donohue
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA; (M.K.A.); (S.T.); (T.M.D.J.); (N.A.O.)
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Natalia A. Osna
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA; (M.K.A.); (S.T.); (T.M.D.J.); (N.A.O.)
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Kusum K. Kharbanda
- Research Service, Veterans Affairs Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA; (M.K.A.); (S.T.); (T.M.D.J.); (N.A.O.)
- Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Department of Biochemistry & Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Correspondence: ; Tel.: +1-402-995-3752; Fax: +1-402-995-4600
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11
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Hammoudeh N, Soukkarieh C, Murphy DJ, Hanano A. Involvement of hepatic lipid droplets and their associated proteins in the detoxification of aflatoxin B 1 in aflatoxin-resistance BALB/C mouse. Toxicol Rep 2020; 7:795-804. [PMID: 32642446 PMCID: PMC7334552 DOI: 10.1016/j.toxrep.2020.06.005] [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: 12/23/2019] [Revised: 06/04/2020] [Accepted: 06/11/2020] [Indexed: 12/14/2022] Open
Abstract
The highly potent carcinogen, Aflatoxin B1, induces liver cancer in many animals including humans but some mice strains are highly resistant. This murine resistance is due to a rapid detoxification of AFB1. Hepatic lipid droplets (LDs) ultimately impact the liver functions but their potential role in AFB1 detoxification has not been addressed. This study describes the structural and functional impacts on hepatic LDs in BALB/C mice after exposure to 44 (low dose) or 663 (high dose) μg AFB1/kg of body weight. After 7 days, the liver of AFB1-dosed mice did not accumulate any detectable AFB1 or its metabolites and this was associated with a net increase in gene transcripts of the AhR-mediating pathway. Of particular interest, the livers of high-dose mice accumulated many more LDs than those of low-dose mice. This was accompanied with a net increase in transcript levels of LD-associated protein-encoding genes including Plin2, Plin3 and Cideb and an alteration in the LDs lipid profiles that could be likely due to the induction of lipoxygenase and cyclooxygenase genes. Interestingly, our data suggest that hepatic LDs catalyze the in vitro activation of AFB1 into AFB1-exo-8,9-epoxide and subsequent hydrolysis of this epoxide into its corresponding dihydrodiol. Finally, transcript levels of CYP1A2, CYP1B1, GSTA3 and EH1 genes were elevated in livers of high-dose mice. These data suggest new roles for hepatic LDs in the trapping and detoxifying of aflatoxins.
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Affiliation(s)
- Nour Hammoudeh
- Department of Animal Biology, Damascus University, Damascus, Syria
| | - Chadi Soukkarieh
- Department of Animal Biology, Damascus University, Damascus, Syria
| | - Denis J Murphy
- Genomics and Computational Biology Group, University of South Wales, Wales, United Kingdom
| | - Abdulsamie Hanano
- Department of Molecular Biology and Biotechnology, Atomic Energy Commission of Syria (AECS), P.O. Box 6091, Damascus, Syria
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12
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Chen F, Yin Y, Chua BT, Li P. CIDE family proteins control lipid homeostasis and the development of metabolic diseases. Traffic 2019; 21:94-105. [PMID: 31746121 DOI: 10.1111/tra.12717] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/03/2019] [Accepted: 11/15/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Feng‐Jung Chen
- Institute of Metabolism and Integrative Biology, the Human Phenome InstituteFudan University, and Zhongshan Hospital of Fudan University Shanghai China
| | - Yesheng Yin
- Institute of Metabolism and Integrative Biology, the Human Phenome InstituteFudan University, and Zhongshan Hospital of Fudan University Shanghai China
| | - Boon Tin Chua
- Institute of Metabolism and Integrative Biology, the Human Phenome InstituteFudan University, and Zhongshan Hospital of Fudan University Shanghai China
| | - Peng Li
- State Key Laboratory of Membrane Biology and Tsinghua‐Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life SciencesTsinghua University Beijing China
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13
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Plin5/p-Plin5 Guards Diabetic CMECs by Regulating FFAs Metabolism Bidirectionally. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:8690746. [PMID: 31772713 PMCID: PMC6854993 DOI: 10.1155/2019/8690746] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 07/23/2019] [Indexed: 01/02/2023]
Abstract
Background Hyper-free fatty acidemia (HFFA) impairs cardiac capillaries, as well as type 2 diabetes mellitus (T2DM). Perilipin 5 (Plin5) maintains metabolic balance of free fatty acids (FFAs) in high oxidative tissues via the states of nonphosphorylation and phosphorylation. However, when facing to T2DM-HFFA, Plin5's role in cardiac microvascular endothelial cells (CMECs) is not defined. Methods In mice of WT or Plin5−/−, T2DM models were rendered by high-fat diet combined with intraperitoneal injection of streptozocin. CMECs isolated from left ventricles were incubated with high glucose (HG) and high FFAs (HFFAs). Plin5 phosphorylation was stimulated by isoproterenol. Plin5 expression was knocked down by small interfering RNA (siRNA). We determined cardiac function by small animal ultrasound, apoptotic rate by flow cytometry, microvessel quantity by immunohistochemistry, microvascular integrity by scanning electron microscopy, intracellular FFAs by spectrophotometry, lipid droplets (LDs) by Nile red staining, mRNAs by quantitative real-time polymerase chain reaction, proteins by western blots, nitric oxide (NO) and reactive oxygen species (ROS) by fluorescent dye staining and enzyme-linked immunosorbent assay kits. Results In CMECs, HFFAs aggravated cell injury induced by HG and activated Plin5 expression. In mice with T2DM-HFFA, Plin5 deficiency reduced number of cardiac capillaries, worsened structural incompleteness, and enhanced diastolic dysfunction. Moreover, in CMECs treated with HG-HFFAs, both ablation and phosphorylation of Plin5 reduced LDs content, increased intracellular FFAs, stimulated mitochondrial β-oxidation, added ROS generation, and reduced the expression and activity of endothelial nitric oxide synthase (eNOS), eventually leading to increased apoptotic rate and decreased NO content, all of which were reversed by N-acetyl-L-cysteine. Conclusion Plin5 preserves lipid balance and cell survival in diabetic CMECs by regulating FFAs metabolism bidirectionally via the states of nonphosphorylation and phosphorylation.
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Yang L, Yang C, Thomes PG, Kharbanda KK, Casey CA, McNiven MA, Donohue TM. Lipophagy and Alcohol-Induced Fatty Liver. Front Pharmacol 2019; 10:495. [PMID: 31143122 PMCID: PMC6521574 DOI: 10.3389/fphar.2019.00495] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 04/18/2019] [Indexed: 12/14/2022] Open
Abstract
This review describes the influence of ethanol consumption on hepatic lipophagy, a selective form of autophagy during which fat-storing organelles known as lipid droplets (LDs) are degraded in lysosomes. During classical autophagy, also known as macroautophagy, all forms of macromolecules and organelles are sequestered in autophagosomes, which, with their cargo, fuse with lysosomes, forming autolysosomes in which the cargo is degraded. It is well established that excessive drinking accelerates intrahepatic lipid biosynthesis, enhances uptake of fatty acids by the liver from the plasma and impairs hepatic secretion of lipoproteins. All the latter contribute to alcohol-induced fatty liver (steatosis). Here, our principal focus is on lipid catabolism, specifically the impact of excessive ethanol consumption on lipophagy, which significantly influences the pathogenesis alcohol-induced steatosis. We review findings, which demonstrate that chronic ethanol consumption retards lipophagy, thereby exacerbating steatosis. This is important for two reasons: (1) Unlike adipose tissue, the liver is considered a fat-burning, not a fat-storing organ. Thus, under normal conditions, lipophagy in hepatocytes actively prevents lipid droplet accumulation, thereby maintaining lipostasis; (2) Chronic alcohol consumption subverts this fat-burning function by slowing lipophagy while accelerating lipogenesis, both contributing to fatty liver. Steatosis was formerly regarded as a benign consequence of heavy drinking. It is now recognized as the "first hit" in the spectrum of alcohol-induced pathologies that, with continued drinking, progresses to more advanced liver disease, liver failure, and/or liver cancer. Complete lipid droplet breakdown requires that LDs be digested to release their high-energy cargo, consisting principally of cholesteryl esters and triacylglycerols (triglycerides). These subsequently undergo lipolysis, yielding free fatty acids that are oxidized in mitochondria to generate energy. Our review will describe recent findings on the role of lipophagy in LD catabolism, how continuous heavy alcohol consumption affects this process, and the putative mechanism(s) by which this occurs.
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Affiliation(s)
- Li Yang
- Division of Gastroenterology and Hepatology, Digestive Disease Institute, Shanghai Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Changqing Yang
- Division of Gastroenterology and Hepatology, Digestive Disease Institute, Shanghai Tongji Hospital, Tongji University School of Medicine, Shanghai, China
| | - Paul G. Thomes
- Research Service, Department of Veterans Affairs, Nebraska-Western Iowa Health Care System, Omaha, NE, United States
- Departments of Internal Medicine and of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Kusum K. Kharbanda
- Research Service, Department of Veterans Affairs, Nebraska-Western Iowa Health Care System, Omaha, NE, United States
- Departments of Internal Medicine and of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Carol A. Casey
- Research Service, Department of Veterans Affairs, Nebraska-Western Iowa Health Care System, Omaha, NE, United States
- Departments of Internal Medicine and of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Mark A. McNiven
- Division of Gastroenterology and Hepatology, Department of Biochemistry and Molecular Biology, Center for Basic Research in Digestive Diseases, Mayo Clinic, Rochester, MN, United States
| | - Terrence M. Donohue
- Research Service, Department of Veterans Affairs, Nebraska-Western Iowa Health Care System, Omaha, NE, United States
- Departments of Internal Medicine and of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, United States
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15
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Peng G, Huang E, Ruan J, Huang L, Liang H, Wei Q, Xie X, Zeng Q, Huang J. Effects of a high energy and low protein diet on hepatic and plasma characteristics and Cidea and Cidec mRNA expression in liver and adipose tissue of laying hens with fatty liver hemorrhagic syndrome. Anim Sci J 2018; 90:247-254. [PMID: 30523654 DOI: 10.1111/asj.13140] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/12/2018] [Accepted: 10/24/2018] [Indexed: 11/30/2022]
Abstract
Cidea and Cidec are two members of Cell death-inducing DNA fragmentation factor-alpha-like effector family proteins, which could be involved in lipid or fat metabolism. To better understand the roles of Cidea and Cidec in fatty liver hemorrhagic syndrome (FLHS), 150 healthy 155-day-old Hyline Brown laying hens were randomly divided into control group (fed with basic diet) and experimental group (fed with high-energy low-protein [HELP] diet). Analysis of the liver by tissue sectioning and hematoxylin and eosin staining showed that the HELP diet induced micro-vesicular steatosis in laying hens. Subsequently, based on the liver color scores and the range of lipid accumulation observed in histological examination, we classified livers with <50% vacuolization as mild FLHS and >50% as severe FLHS. The results showed that the levels of Cidea and Cidec mRNA expression were markedly elevated in the liver and adipose tissues with FLHS and the levels of Cidea and Cidec mRNA expression in the liver with severe FLHS were significantly higher than that in the liver with mild FLHS. Thus, the present study revealed that the Cidea and Cidec genes may be involved in pathways of FLHS formation.
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Affiliation(s)
- Gang Peng
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
| | - Enfu Huang
- Jiangxi Biotech Vocational College, Nanchang, China
| | - Jiming Ruan
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
| | - Liumei Huang
- College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China
| | - Haiping Liang
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
| | - Qing Wei
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
| | - Xianhua Xie
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
| | - Qingjie Zeng
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
| | - Jianzhen Huang
- Jiangxi Provincial Key Laboratory for Animal Health, Institute of Animal Population Health, College of Animal Science and Technology, Jiangxi Agricultural University, Nanchang, China
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16
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Hashani M, Witzel HR, Pawella LM, Lehmann-Koch J, Schumacher J, Mechtersheimer G, Schnölzer M, Schirmacher P, Roth W, Straub BK. Widespread expression of perilipin 5 in normal human tissues and in diseases is restricted to distinct lipid droplet subpopulations. Cell Tissue Res 2018; 374:121-136. [PMID: 29752569 DOI: 10.1007/s00441-018-2845-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 04/18/2018] [Indexed: 12/18/2022]
Abstract
Diseases associated with the accumulation of lipid droplets are increasing in western countries. Lipid droplet biogenesis, structure and degradation are regulated by proteins of the perilipin family. Perilipin 5 has been shown to regulate basal lipolysis in oxidative tissues. We examine perilipin 5 in normal human tissues and in diseases using protein biochemical and microscopic techniques. Perilipin 5 was constitutively located at small lipid droplets in skeletal myocytes, cardiomyocytes and brown adipocytes. In addition, perilipin 5 was detected in the epithelia of the gastrointestinal and urogenital tract, especially in hepatocytes, the mitochondria-rich parietal cells of the stomach, tubular kidney cells and ductal cells of the salivary gland and pancreas. Granular cytoplasmic expression, without a lipid droplet-bound localization was detected elsewhere. In cardiomyopathies, in skeletal muscle diseases and during hepatocyte steatogenesis, perilipin 5 was upregulated and localized to larger and more numerous lipid droplets. In steatotic human hepatocytes, perilipin 5 was moderately increased and colocalized with perilipins 1 and 2 but not with perilipin 3 at lipid droplets. In liver diseases implicated in alterations of mitochondria, such as mitochondriopathies, alcoholic liver disease, Wilson's disease and acute liver injury, perilipin 5 was frequently localized to small lipid droplets and less in the cytoplasm. In tumorigenesis, perilipin 5 was especially upregulated in lipo-, leio- and rhabdomyosarcoma and hepatocellular and renal cell carcinoma. In summary, our study provides evidence that perilipin 5 is not restricted to certain cell types but localizes to distinct lipid droplet subpopulations reflecting a possible function in oxidative energy supply in normal tissues and in diseases.
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Affiliation(s)
- Merita Hashani
- Department of General Pathology, Institute of Pathology, University Hospital, Heidelberg, Germany.,Institute of Pathology, University Hospital of Prishtina, Prishtina, Kosovo
| | - Hagen Roland Witzel
- Institute of Pathology, University Medicine, Johannes Gutenberg-University Mainz, Langenbeckstr. 1, 55131, Mainz, Germany
| | - Lena Maria Pawella
- Department of General Pathology, Institute of Pathology, University Hospital, Heidelberg, Germany
| | - Judith Lehmann-Koch
- Department of General Pathology, Institute of Pathology, University Hospital, Heidelberg, Germany
| | - Jens Schumacher
- Department of Internal Medicine III, Division of Translational and Experimental Oncology, University Hospital Mainz, Mainz, Germany
| | - Gunhild Mechtersheimer
- Department of General Pathology, Institute of Pathology, University Hospital, Heidelberg, Germany
| | - Martina Schnölzer
- Functional Proteome Analysis, German Cancer Research Center Heidelberg (DKFZ), INF 580, Heidelberg, Germany
| | - Peter Schirmacher
- Department of General Pathology, Institute of Pathology, University Hospital, Heidelberg, Germany
| | - Wilfried Roth
- Institute of Pathology, University Medicine, Johannes Gutenberg-University Mainz, Langenbeckstr. 1, 55131, Mainz, Germany
| | - Beate Katharina Straub
- Department of General Pathology, Institute of Pathology, University Hospital, Heidelberg, Germany. .,Institute of Pathology, University Medicine, Johannes Gutenberg-University Mainz, Langenbeckstr. 1, 55131, Mainz, Germany.
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17
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Grasselli E, Canesi L, Portincasa P, Voci A, Vergani L, Demori I. Models of non-Alcoholic Fatty Liver Disease and Potential Translational Value: the Effects of 3,5-L-diiodothyronine. Ann Hepatol 2018; 16:707-719. [PMID: 28809727 DOI: 10.5604/01.3001.0010.2713] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder in industrialized countries and is associated with increased risk of cardiovascular, hepatic and metabolic diseases. Molecular mechanisms on the root of the disrupted lipid homeostasis in NAFLD and potential therapeutic strategies can benefit of in vivo and in vitro experimental models of fatty liver. Here, we describe the high fat diet (HFD)-fed rat in vivo model, and two in vitro models, the primary cultured rat fatty hepatocytes or the FaO rat hepatoma fatty cells, mimicking human NAFLD. Liver steatosis was invariably associated with increased number/size of lipid droplets (LDs) and modulation of expression of genes coding for key genes of lipid metabolism such as peroxisome proliferator-activated receptors (Ppars) and perilipins (Plins). In these models, we tested the anti-steatotic effects of 3,5-L-diiodothyronine (T2), a metabolite of thyroid hormones. T2 markedly reduced triglyceride content and LD size acting on mRNA expression of both Ppars and Plins. T2 also stimulated mitochondrial oxidative metabolism of fatty acids. We conclude that in vivo and especially in vitro models of NAFLD are valuable tools to screen a large number of compounds counteracting the deleterious effect of liver steatosis. Because of the high and negative impact of liver steatosis on human health, ongoing experimental studies from our group are unravelling the ultimate translational value of such cellular models of NAFLD.
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Affiliation(s)
- Elena Grasselli
- University of Genoa, Genoa, Italy Department of Earth, Environmental and Life Sciences-DISTAV
| | - Laura Canesi
- University of Genoa, Genoa, Italy Department of Earth, Environmental and Life Sciences-DISTAV
| | - Piero Portincasa
- University of Bari Medical School, Bari, Italy Department of Biomedical Sciences and Human Oncology Clinica Medica "A. Murri"
| | - Adriana Voci
- University of Genoa, Genoa, Italy Department of Earth, Environmental and Life Sciences-DISTAV
| | - Laura Vergani
- University of Genoa, Genoa, Italy Department of Earth, Environmental and Life Sciences-DISTAV
| | - Ilaria Demori
- University of Genoa, Genoa, Italy Department of Earth, Environmental and Life Sciences-DISTAV
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SREBP1c mediates the effect of acetaldehyde on Cidea expression in Alcoholic fatty liver Mice. Sci Rep 2018; 8:1200. [PMID: 29352167 PMCID: PMC5775393 DOI: 10.1038/s41598-018-19466-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 01/02/2018] [Indexed: 12/18/2022] Open
Abstract
Cell death inducing DNA fragmentation factor-alpha-like A (Cidea) is a member of cell death-inducing DFF45-like effector (CIDE) protein. The initial function of CIDE is the promotion of cell death and DNA fragmentation in mammalian cells. Cidea was recently reported to play critical roles in the development of hepatic steatosis. The purpose of present study is to determine the effect of chronic alcohol intake on Cidea expression in the livers of mice with alcoholic fatty liver disease. Cidea expression was significantly increased in the liver of alcohol-induced fatty liver mice. While, knockdown of Cidea caused lipid droplets numbers reduction. Next, we detected the activity of ALDH2 reduction and the concentration of serum acetaldehyde accumulation in our alcohol-induced fatty liver mice. Cidea expression was elevated in AML12 cells exposed to 100uM acetaldehyde. Interestingly, Dual-luciferase reporter gene assay showed that 100 uM acetaldehyde led to the activation of Cidea reporter gene plasmid which containing SRE element. What’s more, the knockdown of SREBP1c suppressed acetaldehyde-induced Cidea expression. Overall, our findings suggest that Cidea is highly associated with alcoholic fatty liver disease and Cidea expression is specifically induced by acetaldehyde, and this up-regulation is most likely mediated by SREBP1c.
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19
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Gao G, Chen FJ, Zhou L, Su L, Xu D, Xu L, Li P. Control of lipid droplet fusion and growth by CIDE family proteins. Biochim Biophys Acta Mol Cell Biol Lipids 2017. [DOI: 10.1016/j.bbalip.2017.06.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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20
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Kimmel AR, Sztalryd C. The Perilipins: Major Cytosolic Lipid Droplet-Associated Proteins and Their Roles in Cellular Lipid Storage, Mobilization, and Systemic Homeostasis. Annu Rev Nutr 2017; 36:471-509. [PMID: 27431369 DOI: 10.1146/annurev-nutr-071813-105410] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The discovery by Dr. Constantine Londos of perilipin 1, the major scaffold protein at the surface of cytosolic lipid droplets in adipocytes, marked a fundamental conceptual change in the understanding of lipolytic regulation. Focus then shifted from the enzymatic activation of lipases to substrate accessibility, mediated by perilipin-dependent protein sequestration and recruitment. Consequently, the lipid droplet became recognized as a unique, metabolically active cellular organelle and its surface as the active site for novel protein-protein interactions. A new area of investigation emerged, centered on lipid droplets' biology and their role in energy homeostasis. The perilipin family is of ancient origin and has expanded to include five mammalian genes and a growing list of evolutionarily conserved members. Universally, the perilipins modulate cellular lipid storage. This review provides a summary that connects the perilipins to both cellular and whole-body homeostasis.
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Affiliation(s)
- Alan R Kimmel
- Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, The National Institutes of Health, Bethesda, Maryland 20892;
| | - Carole Sztalryd
- The Geriatric Research Education and Clinical Center, Baltimore Veterans Affairs Medical Center, Baltimore, Maryland 21201.,Division of Endocrinology, Department of Medicine, School of Medicine, University of Maryland, Baltimore, Maryland 21201;
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21
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Liu M, Ge R, Liu W, Liu Q, Xia X, Lai M, Liang L, Li C, Song L, Zhen B, Qin J, Ding C. Differential proteomics profiling identifies LDPs and biological functions in high-fat diet-induced fatty livers. J Lipid Res 2017; 58:681-694. [PMID: 28179399 PMCID: PMC5392744 DOI: 10.1194/jlr.m071407] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 02/06/2017] [Indexed: 01/20/2023] Open
Abstract
Eukaryotic cells store neutral lipids in cytoplasmic lipid droplets (LDs) enclosed in a monolayer of phospholipids and associated proteins [LD proteins (LDPs)]. Growing evidence has demonstrated that LDPs play important roles in the pathogenesis of liver diseases. However, the composition of liver LDPs and the role of their alterations in hepatosteatosis are not well-understood. In this study, we performed liver proteome and LD sub-proteome profiling to identify enriched proteins in LDs as LDPs, and quantified their changes in a high-fat diet (HFD)-induced fatty liver model. Among 5,000 quantified liver proteins, 101 were enriched by greater than 10-fold in the LD sub-proteome and were classified as LDPs. Differential profiling of LDPs in HFD-induced fatty liver provided a list of candidate LDPs for functional investigation. We tested the function of an upregulated LDP, S100a10, in vivo with adenovirus-mediated gene silencing and found, unexpectedly, that knockdown of S100a10 accelerated progression of HFD-induced liver steatosis. The S100A10 interactome revealed a connection between S100A10 and lipid transporting proteins, suggesting that S100A10 regulates the development and formation of LDs by transporting and trafficking. This study identified LD-enriched sub-proteome in homeostatic as well as HFD-induced fatty livers, providing a rich resource for the LDP research field.
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Affiliation(s)
- Mingwei Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Rui Ge
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Wanlin Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Qiongming Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Xia Xia
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Mi Lai
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Lizhu Liang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Chen Li
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Lei Song
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Bei Zhen
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China
| | - Jun Qin
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China; Alkek Center for Molecular Discovery, Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030.
| | - Chen Ding
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, National Center for Protein Sciences (PHOENIX Center), Beijing 102206, China; State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Fudan University, Shanghai 200433, China.
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22
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Mahdy MM, El-Ekiaby NM, Hashish RM, Salah RA, Hanafi RS, El-Said Azzazy HM, Abdelaziz AI. miR-29a Promotes Lipid Droplet and Triglyceride Formation in HCV Infection by Inducing Expression of SREBP-1c and CAV1. J Clin Transl Hepatol 2016; 4:293-299. [PMID: 28097097 PMCID: PMC5225148 DOI: 10.14218/jcth.2016.00046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/21/2016] [Accepted: 12/07/2016] [Indexed: 01/18/2023] Open
Abstract
Aims: To examine the regulation of SREBP-1c and CAV1 by microRNA-29a (miR-29a) in cells infected with hepatitis C virus (HCV) in an attempt to control HCV-induced non-alcoholic fatty liver disease. Methods: In order to examine the manipulation of SREBP-1c and CAV1 by miR-29a, oleic acid (OA)-treated JFH-I-infected Huh-7 cells were used. OA was added 24 h post-transfection and gene expression was investigated by qRT-PCR at 48 h post treatment. The functional impact of the observed alteration in SREBP-1c and CAV1 expression was analyzed by examining lipid droplet (LD) and triglyceride (TG) content at 72 h post-OA treatment using light microscopy and spectrophotometry, respectively. Viral load was quantified by qRT-PCR at 72 h post-transfection. Results: OA treatment induced the expression of miR-29a and SREBP-1c, as compared to untreated cells. Forced miR-29a expression led to a significant up-regulation of SREBP-1c as well as CAV1 compared to mock untransfected cells. Ectopic expression of miR-29a resulted in a marked increase in LDs and their respective TGs, while miR-29a antagomirs decreased both the LD and TG content compared to mock untransfected cells. Moreover, forcing the expression of miR-29a in JFH-1 HCV-infected Huh-7 cells resulted in 53% reduction in viral titers compared to mock untransfected Huh-7 cells. Conclusion: Inducing miR-29a expression significantly induces SREBP-1c and CAV1 expression, thereby increasing LDs as well as their respective TGs. Nonetheless, forcing the expression of miR-29a resulted in reduction of HCV RNA levels in Huh-7 cells.
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Affiliation(s)
| | - Nada Magdy El-Ekiaby
- Department of Pharmacology and Toxicology, German University in Cairo, New Cairo City, Egypt
- School of Medicine, NewGiza University, Cairo, Egypt
| | - Rana Mahmoud Hashish
- Department of Pharmaceutical Biology, German University in Cairo, New Cairo City, Egypt
| | - Radwa Ayman Salah
- Department of Stem Cells and Regenerative Medicine, Zewail City of Science and Technology, Giza, Egypt
| | - Rasha Sayed Hanafi
- Department of Pharmaceutical Chemistry, German University in Cairo, New Cairo City, Egypt
| | | | - Ahmed Ihab Abdelaziz
- Department of Pharmacology and Toxicology, German University in Cairo, New Cairo City, Egypt
- School of Medicine, NewGiza University, Cairo, Egypt
- *Correspondence to: Ahmed Ihab Abdelaziz, Department of Molecular Medicine, School of Medicine, Newgiza University, Cairo 11431, Egypt. Tel: +20-238277847, E-mail:
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23
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Zhang X, Wang Y, Liu P. Omic studies reveal the pathogenic lipid droplet proteins in non-alcoholic fatty liver disease. Protein Cell 2016; 8:4-13. [PMID: 27757845 PMCID: PMC5233612 DOI: 10.1007/s13238-016-0327-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 09/19/2016] [Indexed: 12/21/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is an epidemic metabolic condition driven by an underlying lipid homeostasis disorder. The lipid droplet (LD), the main organelle involved in neutral lipid storage and hydrolysis, is a potential target for NAFLD therapeutic treatment. In this review, we summarize recent progress elucidating the connections between LD-associated proteins and NAFLD found by genome-wide association studies (GWAS), genomic and proteomic studies. Finally, we discuss a possible mechanism by which the protein 17β-hydroxysteroid dehydrogenase 13 (17β-HSD13) may promote the development of NAFLD.
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Affiliation(s)
- Xuelin Zhang
- School of Kinesiology and Health, Capital University of Physical Education and Sports, Beijing, 100191, China.
| | - Yang Wang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.
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24
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Jouffe C, Gobet C, Martin E, Métairon S, Morin-Rivron D, Masoodi M, Gachon F. Perturbed rhythmic activation of signaling pathways in mice deficient for Sterol Carrier Protein 2-dependent diurnal lipid transport and metabolism. Sci Rep 2016; 6:24631. [PMID: 27097688 PMCID: PMC4838911 DOI: 10.1038/srep24631] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 03/29/2016] [Indexed: 01/22/2023] Open
Abstract
Through evolution, most of the living species have acquired a time keeping system to anticipate daily changes caused by the rotation of the Earth. In all of the systems this pacemaker is based on a molecular transcriptional/translational negative feedback loop able to generate rhythmic gene expression with a period close to 24 hours. Recent evidences suggest that post-transcriptional regulations activated mostly by systemic cues play a fundamental role in the process, fine tuning the time keeping system and linking it to animal physiology. Among these signals, we consider the role of lipid transport and metabolism regulated by SCP2. Mice harboring a deletion of the Scp2 locus present a modulated diurnal accumulation of lipids in the liver and a perturbed activation of several signaling pathways including PPARα, SREBP, LRH-1, TORC1 and its upstream regulators. This defect in signaling pathways activation feedbacks upon the clock by lengthening the circadian period of animals through post-translational regulation of core clock regulators, showing that rhythmic lipid transport is a major player in the establishment of rhythmic mRNA and protein expression landscape.
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Affiliation(s)
- Céline Jouffe
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, CH-1011, Switzerland.,Department of Diabetes and Circadian Rhythms, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland
| | - Cédric Gobet
- Department of Diabetes and Circadian Rhythms, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland.,Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Eva Martin
- Department of Diabetes and Circadian Rhythms, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland
| | - Sylviane Métairon
- Functional Genomic, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland
| | - Delphine Morin-Rivron
- Department of Gastro-Intestinal Health &Microbiome, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland
| | - Mojgan Masoodi
- Department of Gastro-Intestinal Health &Microbiome, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland.,Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, ON, M5S 3E2, Canada
| | - Frédéric Gachon
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, CH-1011, Switzerland.,Department of Diabetes and Circadian Rhythms, Nestlé Institute of Health Sciences, CH-1015 Lausanne, Switzerland.,Faculty of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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25
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Zhu YX, Zhang ML, Zhong Y, Wang C, Jia WP. Modulation Effect of Peroxisome Proliferator-Activated Receptor Agonists on Lipid Droplet Proteins in Liver. J Diabetes Res 2016; 2016:8315454. [PMID: 26770990 PMCID: PMC4684860 DOI: 10.1155/2016/8315454] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 06/02/2015] [Accepted: 07/01/2015] [Indexed: 12/14/2022] Open
Abstract
Peroxisome proliferator-activated receptor (PPAR) agonists are used for treating hyperglycemia and type 2 diabetes. However, the mechanism of action of these agonists is still under investigation. The lipid droplet-associated proteins FSP27/CIDEC and LSDP5, regulated directly by PPARγ and PPARα, are associated with hepatic steatosis and insulin sensitivity. Here, we evaluated the expression levels of FSP27/CIDEC and LSDP5 and the regulation of these proteins by consumption of a high-fat diet (HFD) or administration of PPAR agonists. Mice with diet-induced obesity were treated with the PPARγ or PPARα agonist, pioglitazone or fenofibrate, respectively. Liver tissues from db/db diabetic mice and human were also collected. Interestingly, FSP27/CIEDC was expressed in mouse and human livers and was upregulated in obese C57BL/6J mice. Fenofibrate treatment decreased hepatic triglyceride (TG) content and FSP27/CIDEC protein expression in mice fed an HFD diet. In mice, LSDP5 was not detected, even in the context of insulin resistance or treatment with PPAR agonists. However, LSDP5 was highly expressed in humans, with elevated expression observed in the fatty liver. We concluded that fenofibrate greatly decreased hepatic TG content and FSP27/CIDEC protein expression in mice fed an HFD, suggesting a potential regulatory role for fenofibrate in the amelioration of hepatic steatosis.
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Affiliation(s)
- Yun-Xia Zhu
- Department of Geriatrics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Ming-Liang Zhang
- Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Yuan Zhong
- Department of Geriatrics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
| | - Chen Wang
- Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
- Shanghai Key Laboratory of Diabetes Mellitus, 600 Yishan Road, Shanghai 200233, China
- Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
- *Chen Wang:
| | - Wei-Ping Jia
- Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
- Shanghai Key Laboratory of Diabetes Mellitus, 600 Yishan Road, Shanghai 200233, China
- Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, 600 Yishan Road, Shanghai 200233, China
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26
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Carr RM, Ahima RS. Pathophysiology of lipid droplet proteins in liver diseases. Exp Cell Res 2015; 340:187-92. [PMID: 26515554 DOI: 10.1016/j.yexcr.2015.10.021] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 10/21/2015] [Accepted: 10/23/2015] [Indexed: 02/07/2023]
Abstract
Cytosolic lipid droplets (LDs) are present in most cell types, and consist of a core comprising neutral lipids, mainly triglycerides and sterol esters, surrounded by a monolayer of phospholipids. LDs are heterogeneous in their structure, chemical composition, and tissue distribution. LDs are coated by several proteins, including perilipins and other structural proteins, lipogenic enzymes, lipases and membrane-trafficking proteins. Five proteins of the perilipin (PLIN) family (PLIN1 (perilipin), PLIN2 (adipose differentiation-related protein), PLIN3 (tail-interacting protein of 47kDa), PLIN4 (S3-12), and PLIN5 (myocardial lipid droplet protein)), are associated with LD formation. More recently, the CIDE family of proteins, hypoxia-inducible protein 2 (HIG2), and patanin-like phospholipase domain-containing 3 (PNPLA3) have also gained attention in hepatic LD biology. Evidence suggests that LD proteins are involved in the pathophysiology of fatty liver diseases characterized by excessive lipid accumulation in hepatocytes. This review article will focus on how hepatic LDs and their associated proteins are involved in the pathogenesis of three chronic liver conditions: hepatitis C virus infection, non-alcoholic fatty liver disease, and alcoholic liver disease.
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Affiliation(s)
- Rotonya M Carr
- Department of Medicine, Gastroenterology and Hepatology Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Rexford S Ahima
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
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27
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Mason RR, Watt MJ. Unraveling the roles of PLIN5: linking cell biology to physiology. Trends Endocrinol Metab 2015; 26:144-52. [PMID: 25682370 DOI: 10.1016/j.tem.2015.01.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 01/20/2015] [Accepted: 01/21/2015] [Indexed: 01/07/2023]
Abstract
The discovery of perilipin (PLIN) 1 provided a major conceptual shift in the understanding of adipose tissue lipolysis and generated intense interest in lipid droplet biology research. The subsequent discovery of other PLIN proteins revealed unique tissue distribution profiles, subcellular locations, and lipid-binding properties and divergent cellular functions. PLIN5 is highly expressed in oxidative tissues such as skeletal muscle, liver, and heart and is central to lipid homeostasis in these tissues. Studies in cell systems have ascribed several metabolic roles to PLIN5 and demonstrated interactions with other proteins that are requisite for these functions. We examine recent in vivo studies and ask whether the evidence from the cell biology approaches is consistent with the physiological roles of PLIN5.
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Affiliation(s)
- Rachael R Mason
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
| | - Matthew J Watt
- Department of Physiology, Monash University, Clayton, Victoria 3800, Australia.
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28
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Schweitzer GG, Chen Z, Gan C, McCommis KS, Soufi N, Chrast R, Mitra MS, Yang K, Gross RW, Finck BN. Liver-specific loss of lipin-1-mediated phosphatidic acid phosphatase activity does not mitigate intrahepatic TG accumulation in mice. J Lipid Res 2015; 56:848-58. [PMID: 25722343 DOI: 10.1194/jlr.m055962] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Lipin proteins (lipin 1, 2, and 3) regulate glycerolipid homeostasis by acting as phosphatidic acid phosphohydrolase (PAP) enzymes in the TG synthesis pathway and by regulating DNA-bound transcription factors to control gene transcription. Hepatic PAP activity could contribute to hepatic fat accumulation in response to physiological and pathophysiological stimuli. To examine the role of lipin 1 in regulating hepatic lipid metabolism, we generated mice that are deficient in lipin-1-encoded PAP activity in a liver-specific manner (Alb-Lpin1(-/-) mice). This allele of lipin 1 was still able to transcriptionally regulate the expression of its target genes encoding fatty acid oxidation enzymes, and the expression of these genes was not affected in Alb-Lpin1(-/-) mouse liver. Hepatic PAP activity was significantly reduced in mice with liver-specific lipin 1 deficiency. However, hepatocytes from Alb-Lpin1(-/-) mice had normal rates of TG synthesis, and steady-state hepatic TG levels were unaffected under fed and fasted conditions. Furthermore, Alb-Lpin1(-/-) mice were not protected from intrahepatic accumulation of diacylglycerol and TG after chronic feeding of a diet rich in fat and fructose. Collectively, these data demonstrate that marked deficits in hepatic PAP activity do not impair TG synthesis and accumulation under acute or chronic conditions of lipid overload.
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Affiliation(s)
| | - Zhouji Chen
- Washington University School of Medicine, St. Louis, MO 63110
| | - Connie Gan
- Washington University School of Medicine, St. Louis, MO 63110
| | - Kyle S McCommis
- Washington University School of Medicine, St. Louis, MO 63110
| | - Nisreen Soufi
- Washington University School of Medicine, St. Louis, MO 63110
| | - Roman Chrast
- Department of Medical Genetics, University of Lausanne, 1005 Lausanne, Switzerland
| | | | - Kui Yang
- Washington University School of Medicine, St. Louis, MO 63110
| | - Richard W Gross
- Washington University School of Medicine, St. Louis, MO 63110
| | - Brian N Finck
- Washington University School of Medicine, St. Louis, MO 63110
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29
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Targeting Hepatic Glycerolipid Synthesis and Turnover to Treat Fatty Liver Disease. ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/498369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of metabolic abnormalities ranging from simple hepatic steatosis (accumulation of neutral lipid) to development of steatotic lesions, steatohepatitis, and cirrhosis. NAFLD is extremely prevalent in obese individuals and with the epidemic of obesity; nonalcoholic steatohepatitis (NASH) has become the most common cause of liver disease in the developed world. NASH is rapidly emerging as a prominent cause of liver failure and transplantation. Moreover, hepatic steatosis is tightly linked to risk of developing insulin resistance, diabetes, and cardiovascular disease. Abnormalities in hepatic lipid metabolism are part and parcel of the development of NAFLD and human genetic studies and work conducted in experimentally tractable systems have identified a number of enzymes involved in fat synthesis and degradation that are linked to NAFLD susceptibility as well as progression to NASH. The goal of this review is to summarize the current state of our knowledge on these pathways and focus on how they contribute to etiology of NAFLD and related metabolic diseases.
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30
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Pawella LM, Hashani M, Eiteneuer E, Renner M, Bartenschlager R, Schirmacher P, Straub BK. Perilipin discerns chronic from acute hepatocellular steatosis. J Hepatol 2014; 60:633-42. [PMID: 24269473 DOI: 10.1016/j.jhep.2013.11.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Revised: 11/06/2013] [Accepted: 11/11/2013] [Indexed: 12/04/2022]
Abstract
BACKGROUND & AIMS Hepatocellular steatosis is the most frequent liver disease in the western world and may develop further to steatohepatitis, liver cirrhosis and hepatocellular carcinoma. We have previously shown that lipid droplet (LD)-associated proteins of the perilipin/PAT-family are differentially expressed in hepatocyte steatosis and that perilipin is expressed de novo. The aim of this study was to determine the conditions for the temporal regulation of de novo synthesis of perilipin in vitro and in vivo. METHODS Immunohistochemical PAT-analysis was performed with over 120 liver biopsies of different etiology and duration of steatosis. Steatosis was induced in cultured hepatocytic cells with combinations of lipids, steatogenic substances and DMSO for up to 40 days under conditions of stable down-regulation of adipophilin and/or TIP47. RESULTS Whereas perilipin and adipophilin were expressed in human chronic liver disease irrespective of the underlying etiology, in acute/microvesicular steatosis TIP47, and MLDP were recruited from the cytoplasm to LDs, adipophilin was strongly increased, but perilipin was virtually absent. In long-term steatosis models in vitro, TIP47, MLDP, adipophilin, and finally perilipin were gradually induced. Perilipin and associated formation of LDs were intricately regulated on the transcriptional (PPARs, C/EBPs, SREBP), post-transcriptional, and post-translational level (TAG-amount, LD-fusion, phosphorylation-dependent lipolysis). In long-term steatosis models under stable down-regulation of adipophilin and/or TIP47, MLDP substituted for TIP47, and perilipin for adipophilin. CONCLUSIONS LD-maturation in hepatocytes in vivo and in vitro involves sequential expression of TIP47, MLDP, adipophilin and finally perilipin. Thus, perilipin might be used for the differential diagnosis of chronic vs. acute steatosis.
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Affiliation(s)
- Lena Maria Pawella
- Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany
| | - Merita Hashani
- Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany
| | - Eva Eiteneuer
- Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany
| | - Marcus Renner
- Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany
| | - Ralf Bartenschlager
- Department for Infectious Diseases, Molecular Virology, Im Neuenheimer Feld 345, D-69120 Heidelberg, Germany
| | - Peter Schirmacher
- Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany
| | - Beate Katharina Straub
- Department of General Pathology, Institute of Pathology, Im Neuenheimer Feld 224, D-69120 Heidelberg, Germany.
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31
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Chamorro-García R, Sahu M, Abbey RJ, Laude J, Pham N, Blumberg B. Transgenerational inheritance of increased fat depot size, stem cell reprogramming, and hepatic steatosis elicited by prenatal exposure to the obesogen tributyltin in mice. ENVIRONMENTAL HEALTH PERSPECTIVES 2013; 121:359-66. [PMID: 23322813 PMCID: PMC3621201 DOI: 10.1289/ehp.1205701] [Citation(s) in RCA: 221] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 01/11/2013] [Indexed: 05/18/2023]
Abstract
BACKGROUND We have previously shown that exposure to tributyltin (TBT) modulates critical steps of adipogenesis through RXR/PPARγ and that prenatal TBT exposure predisposes multipotent mesenchymal stem cells (MSCs) to become adipocytes by epigenetic imprinting into the memory of the MSC compartment. OBJECTIVE We tested whether the effects of prenatal TBT exposure were heritable in F2 and F3 generations. METHODS We exposed C57BL/6J female mice (F0) to DMSO vehicle, the pharmaceutical obesogen rosiglitazone (ROSI), or TBT (5.42, 54.2, or 542 nM) throughout pregnancy via the drinking water. F1 offspring were bred to yield F2, and F2 mice were bred to produce F3. F1 animals were exposed in utero and F2 mice were potentially exposed as germ cells in the F1, but F3 animals were never exposed to the chemicals. We analyzed the effects of these exposures on fat depot weights, adipocyte number, adipocyte size, MSC programming, hepatic lipid accumulation, and hepatic gene expression in all three generations. DISCUSSION Prenatal TBT exposure increased most white adipose tissue (WAT) depot weights, adipocyte size, and adipocyte number, and reprogrammed MSCs toward the adipocyte lineage at the expense of bone in all three generations. Prenatal TBT exposure led to hepatic lipid accumulation and up-regulated hepatic expression of genes involved in lipid storage/transport, lipogenesis, and lipolysis in all three subsequent generations. CONCLUSIONS Prenatal TBT exposure produced transgenerational effects on fat depots and induced a phenotype resembling nonalcoholic fatty liver disease through at least the F3 generation. These results show that early-life obesogen exposure can have lasting effects.
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Affiliation(s)
- Raquel Chamorro-García
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California 92697-2300, USA
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32
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McManaman JL, Bales ES, Orlicky DJ, Jackman M, MacLean PS, Cain S, Crunk AE, Mansur A, Graham CE, Bowman TA, Greenberg AS. Perilipin-2-null mice are protected against diet-induced obesity, adipose inflammation, and fatty liver disease. J Lipid Res 2013; 54:1346-59. [PMID: 23402988 DOI: 10.1194/jlr.m035063] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The cytoplasmic lipid droplet (CLD) protein perilipin-2 (Plin2) is expressed in multiple nonadipose tissues, where it is thought to play a role in regulating their lipid storage properties. However, the extent to which Plin2 functions in nutrient utilization and metabolism, or how it influences the consequences of over-feeding, remains unclear. In this study, we demonstrate that the absence of Plin2 prevents high-fat diet(HFD)-induced obesity in male and female mice. This response is associated with increased formation of subcutaneous beige adipocyte cells with uncoupling protein 1 expression, and amelioration of inflammatory foci formation in white adipose tissue and steatosis in the liver. Experiments demonstrate that Plin2 loss results in reduced energy intake and increased physical activity in response to HFD feeding. Our study provides the first evidence that Plin2 contributes to HFD-induced obesity by modulating food intake, and that its absence prevents obesity-associated adipose tissue inflammatory foci and liver steatosis.
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Affiliation(s)
- James L McManaman
- Division of Basic Reproductive Sciences, University of Colorado School of Medicine, Aurora, CO, USA.
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33
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Mice with an adipocyte-specific lipin 1 separation-of-function allele reveal unexpected roles for phosphatidic acid in metabolic regulation. Proc Natl Acad Sci U S A 2012; 110:642-7. [PMID: 23267081 DOI: 10.1073/pnas.1213493110] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lipin 1 is a coregulator of DNA-bound transcription factors and a phosphatidic acid (PA) phosphatase (PAP) enzyme that catalyzes a critical step in the synthesis of glycerophospholipids. Lipin 1 is highly expressed in adipocytes, and constitutive loss of lipin 1 blocks adipocyte differentiation; however, the effects of Lpin1 deficiency in differentiated adipocytes are unknown. Here we report that adipocyte-specific Lpin1 gene recombination unexpectedly resulted in expression of a truncated lipin 1 protein lacking PAP activity but retaining transcriptional regulatory function. Loss of lipin 1-mediated PAP activity in adipocytes led to reduced glyceride synthesis and increased PA content. Characterization of the deficient mice also revealed that lipin 1 normally modulates cAMP-dependent signaling through protein kinase A to control lipolysis by metabolizing PA, which is an allosteric activator of phosphodiesterase 4 and the molecular target of rapamycin. Consistent with these findings, lipin 1 expression was significantly related to adipose tissue lipolytic rates and protein kinase A signaling in adipose tissue of obese human subjects. Taken together, our findings identify lipin 1 as a reciprocal regulator of triglyceride synthesis and hydrolysis in adipocytes, and suggest that regulation of lipolysis by lipin 1 is mediated by PA-dependent modulation of phosphodiesterase 4.
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34
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Abstract
Nonalcoholic steatohepatitis (NASH) is defined histopathologically by the presence of macrovesicular steatosis, cellular ballooning, and inflammation. NASH represents a complex multifactorial disease that typically occurs within the context of the metabolic syndrome. NASH lacks homogeneity, and other forms of NASH can present atypically. Less than 50% of patients with NASH respond to pharmacologic treatment, which speaks to this heterogeneity. The authors discuss drugs, disease entities, and nutritional states that can cause or exacerbate underlying NASH indirectly through worsening insulin resistance or directly by interfering with lipid metabolism, promoting oxidative injury, or activating inflammatory pathways.
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Affiliation(s)
- Soledad Larrain
- Division of Gastroenterology & Hepatology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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Zhou L, Xu L, Ye J, Li D, Wang W, Li X, Wu L, Wang H, Guan F, Li P. Cidea promotes hepatic steatosis by sensing dietary fatty acids. Hepatology 2012; 56:95-107. [PMID: 22278400 DOI: 10.1002/hep.25611] [Citation(s) in RCA: 134] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 01/17/2012] [Indexed: 01/09/2023]
Abstract
UNLABELLED High levels of dietary saturated fat have been closely associated with the development of hepatic steatosis, but the factors that mediate this process remain elusive. Here, we observed that the level of cell death-inducing DNA fragmentation factor-alpha-like effector a (Cidea) expression was highly correlated with the severity of hepatic steatosis in humans. Overexpression of Cidea in mouse liver resulted in increased hepatic lipid accumulation and the formation of large lipid droplets (LDs). In contrast, mice with a Cidea deficiency had decreased lipid accumulation and alleviated hepatic steatosis when they received a high-fat-diet feeding or in ob/ob mice. Furthermore, the knockdown of Cidea in livers of ob/ob mice resulted in significantly reduced hepatic lipid accumulation and smaller LDs. Importantly, we observed that Cidea expression in hepatocytes was specifically induced by saturated fatty acids (FAs), and such induction was reduced when sterol response element-binding protein (SREBP)1c was knocked down. In contrast, the overexpression of SREBP1c restored the saturated FA-induced expression of Cidea. In addition, we observed that the stability of Cidea protein in hepatocytes increased significantly in response to treatment with FAs. CONCLUSION Cidea plays critical roles in promoting hepatic lipid accumulation and in the development of hepatic steatosis by acting as a sensor that responds to diets that contain FAs.
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Affiliation(s)
- Linkang Zhou
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
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Frochot V, Alqub M, Cattin AL, Carrière V, Houllier A, Baraille F, Barbot L, Saint-Just S, Ribeiro A, Lacasa M, Cardot P, Chambaz J, Rousset M, Lacorte JM. The transcription factor HNF-4α: a key factor of the intestinal uptake of fatty acids in mouse. Am J Physiol Gastrointest Liver Physiol 2012; 302:G1253-63. [PMID: 22461026 DOI: 10.1152/ajpgi.00329.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
With an excessive postprandial accumulation of intestine-derived, triglyceride-rich lipoproteins being a risk factor of cardiovascular diseases, it is essential to characterize the mechanisms controlling the intestinal absorption of dietary lipids. Our aim was to investigate the role of the transcription factor hepatocyte nuclear factor (HNF)-4α in this process. We used transgenic mice with a specific and inducible intestinal knockout of Hnf-4α gene. One hour after a lipid bolus, in the presence of the lipase inhibitor tyloxapol, lower amounts of triglycerides were found in both plasma and intestinal epithelium of the intestine-specific Hnf-4α knockout (Hnf-4α(intΔ)) mice compared with the Hnf-4α(loxP/loxP) control mice. These discrepancies were due to a net decrease of the intestinal uptake of fatty acid in Hnf-4α(intΔ) mice compared with Hnf-4α(loxP/loxP) mice, as assessed by the amount of radioactivity that was recovered in intestine and plasma after gavage with labeled triolein or oleic acid, or in intestinal epithelial cells isolated from jejunum after a supply of labeled oleic acid-containing micelles. This decreased fatty acid uptake was associated with significant lower levels of the fatty acid transport protein-4 mRNA and protein along the intestinal tract and with a lower acyl-CoA synthetase activity in Hnf-4α(intΔ) mice compared with the control mice. We conclude that the transcription factor HNF-4α is a key factor of the intestinal absorption of dietary lipids, which controls this process as early as in the initial step of fatty acid uptake by enterocytes.
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Affiliation(s)
- Vincent Frochot
- Centre de Recherche des Cordeliers, Université Pierre et Marie Curie, UMRS, Paris, France
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Harris LALS, Shew TM, Skinner JR, Wolins NE. A single centrifugation method for isolating fat droplets from cells and tissues. J Lipid Res 2012; 53:1021-1025. [PMID: 22327205 DOI: 10.1194/jlr.d023598] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fat droplets (FDs) have important roles in cellular energy regulation. Isolating FDs from either cells or tissue continues to be important for studying these organelles. Here, we describe a procedure wherein whole homogenates of cultured cells or tissue are fractionated with a single centrifugation step in a standard microcentrifuge. This procedure reproducibly yields three fractions highly enriched in either FDs, soluble cellular components, or sedimentable organelles/membranes.
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Affiliation(s)
- Lydia-Ann L S Harris
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Trevor M Shew
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - James R Skinner
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO
| | - Nathan E Wolins
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO.
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38
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Gandotra S, Lim K, Girousse A, Saudek V, O'Rahilly S, Savage DB. Human frame shift mutations affecting the carboxyl terminus of perilipin increase lipolysis by failing to sequester the adipose triglyceride lipase (ATGL) coactivator AB-hydrolase-containing 5 (ABHD5). J Biol Chem 2011; 286:34998-5006. [PMID: 21757733 PMCID: PMC3186430 DOI: 10.1074/jbc.m111.278853] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Indexed: 01/03/2023] Open
Abstract
Perilipin (PLIN1) is a constitutive adipocyte lipid droplet coat protein. N-terminal amphipathic helices and central hydrophobic stretches are thought to anchor it on the lipid droplet, where it appears to function as a scaffold protein regulating lipase activity. We recently identified two different C-terminal PLIN1 frame shift mutations (Leu-404fs and Val-398fs) in patients with a novel subtype of partial lipodystrophy, hypertriglyceridemia, severe insulin resistance, and type 2 diabetes (Gandotra, S., Le Dour, C., Bottomley, W., Cervera, P., Giral, P., Reznik, Y., Charpentier, G., Auclair, M., Delépine, M., Barroso, I., Semple, R. K., Lathrop, M., Lascols, O., Capeau, J., O'Rahilly, S., Magré, J., Savage, D. B., and Vigouroux, C. (2011) N. Engl. J. Med. 364, 740-748.) When overexpressed in preadipocytes, both mutants fail to inhibit basal lipolysis. Here we used bimolecular fluorescence complementation assays to show that the mutants fail to bind ABHD5, permitting its constitutive coactivation of ATGL, resulting in increased basal lipolysis. siRNA-mediated knockdown of either ABHD5 or ATGL expression in the stably transfected cells expressing mutant PLIN1 reduced basal lipolysis. These insights from naturally occurring human variants suggest that the C terminus sequesters ABHD5 and thus inhibits basal ATGL activity. The data also suggest that pharmacological inhibition of ATGL could have therapeutic potential in patients with this rare but metabolically serious disorder.
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Affiliation(s)
- Sheetal Gandotra
- From the Institute of Metabolic Science Metabolic Research Laboratories (IMS MRL) and the Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, United Kingdom
| | - Koini Lim
- From the Institute of Metabolic Science Metabolic Research Laboratories (IMS MRL) and the Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, United Kingdom
| | - Amandine Girousse
- From the Institute of Metabolic Science Metabolic Research Laboratories (IMS MRL) and the Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, United Kingdom
| | - Vladimir Saudek
- From the Institute of Metabolic Science Metabolic Research Laboratories (IMS MRL) and the Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, United Kingdom
| | - Stephen O'Rahilly
- From the Institute of Metabolic Science Metabolic Research Laboratories (IMS MRL) and the Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, United Kingdom
| | - David B. Savage
- From the Institute of Metabolic Science Metabolic Research Laboratories (IMS MRL) and the Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, United Kingdom
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Abstract
PURPOSE OF REVIEW To summarize currently available information about the mechanisms involved in liver fat accumulation. RECENT FINDINGS The contribution of functional genomics approaches, such as those represented by high-throughput analysis and genetically modified mice, may envision a complex network involving fatty acid, triglyceride and phospholipid metabolisms and lipid droplet dynamics. Likewise, it may pose an exquisite regulation exerted through insulin, glucocorticoids, thyroid hormones, transcription factors and microRNAs, orchestrated with sexual differences and able to respond to environmental factors such as nutritional or viral influences among others. SUMMARY The information gathered will facilitate further research to complete gaps of interacting pieces among regulators and new contributing agents emerging from high-throughput analyses. With this new paradigm, new biomarkers able to discriminate the progression of hepatic steatosis into human steatohepatitis will eventually emerge, and hopefully new therapeutic approaches will be developed.
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Affiliation(s)
- José M Lou-Bonafonte
- Departamento de Farmacología y Fisiología, Facultad de Ciencias de Salud y del Deporte, Instituto de Investigación Sanitaria de Aragón, Universidad de Zaragoza, Zaragoza, Spain
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40
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Greenberg AS, Coleman RA, Kraemer FB, McManaman JL, Obin MS, Puri V, Yan QW, Miyoshi H, Mashek DG. The role of lipid droplets in metabolic disease in rodents and humans. J Clin Invest 2011; 121:2102-10. [PMID: 21633178 DOI: 10.1172/jci46069] [Citation(s) in RCA: 470] [Impact Index Per Article: 36.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Lipid droplets (LDs) are intracellular organelles that store neutral lipids within cells. Over the last two decades there has been a dramatic growth in our understanding of LD biology and, in parallel, our understanding of the role of LDs in health and disease. In its simplest form, the LD regulates the storage and hydrolysis of neutral lipids, including triacylglycerol and/or cholesterol esters. It is becoming increasingly evident that alterations in the regulation of LD physiology and metabolism influence the risk of developing metabolic diseases such as diabetes. In this review we provide an update on the role of LD-associated proteins and LDs in metabolic disease.
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Affiliation(s)
- Andrew S Greenberg
- Obesity and Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts 02111, USA.
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41
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Harris TE, Finck BN. Dual function lipin proteins and glycerolipid metabolism. Trends Endocrinol Metab 2011; 22:226-33. [PMID: 21470873 PMCID: PMC3118913 DOI: 10.1016/j.tem.2011.02.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 02/17/2011] [Accepted: 02/20/2011] [Indexed: 12/11/2022]
Abstract
Lipin family proteins are emerging as crucial regulators of lipid metabolism. In triglyceride synthesis, lipins act as lipid phosphatase enzymes at the endoplasmic reticular membrane, catalyzing the dephosphorylation of phosphatidic acid to form diacylglycerol, which is the penultimate step in this process. However, lipin proteins are not integral membrane proteins, and can rapidly translocate within the cell. In fact, emerging evidence suggests that lipins also play crucial roles in the nucleus as transcriptional regulatory proteins. Thus, lipins are poised to regulate cellular lipid metabolism at multiple regulatory nodal points. This review summarizes the history of lipin proteins, and discusses the current state of our understanding of lipin biology.
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Affiliation(s)
- Thurl E Harris
- Department of Pharmacology, University of Virginia School of Medicine, Charlottesville, VA, USA
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42
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Garbow JR, Doherty JM, Schugar RC, Travers S, Weber ML, Wentz AE, Ezenwajiaku N, Cotter DG, Brunt EM, Crawford PA. Hepatic steatosis, inflammation, and ER stress in mice maintained long term on a very low-carbohydrate ketogenic diet. Am J Physiol Gastrointest Liver Physiol 2011; 300:G956-67. [PMID: 21454445 PMCID: PMC3119109 DOI: 10.1152/ajpgi.00539.2010] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 03/29/2011] [Indexed: 01/31/2023]
Abstract
Low-carbohydrate diets are used to manage obesity, seizure disorders, and malignancies of the central nervous system. These diets create a distinctive, but incompletely defined, cellular, molecular, and integrated metabolic state. Here, we determine the systemic and hepatic effects of long-term administration of a very low-carbohydrate, low-protein, and high-fat ketogenic diet, serially comparing these effects to a high-simple-carbohydrate, high-fat Western diet and a low-fat, polysaccharide-rich control chow diet in C57BL/6J mice. Longitudinal measurement of body composition, serum metabolites, and intrahepatic fat content, using in vivo magnetic resonance spectroscopy, reveals that mice fed the ketogenic diet over 12 wk remain lean, euglycemic, and hypoinsulinemic but accumulate hepatic lipid in a temporal pattern very distinct from animals fed the Western diet. Ketogenic diet-fed mice ultimately develop systemic glucose intolerance, hepatic endoplasmic reticulum stress, steatosis, cellular injury, and macrophage accumulation, but surprisingly insulin-induced hepatic Akt phosphorylation and whole-body insulin responsiveness are not impaired. Moreover, whereas hepatic Pparg mRNA abundance is augmented by both high-fat diets, each diet confers splice variant specificity. The distinctive nutrient milieu created by long-term administration of this low-carbohydrate, low-protein ketogenic diet in mice evokes unique signatures of nonalcoholic fatty liver disease and whole-body glucose homeostasis.
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Affiliation(s)
- Joel R Garbow
- Department of 1Medicine, Washington University, St. Louis, Missouri 63110, USA
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43
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Bai L, Jia Y, Viswakarma N, Huang J, Vluggens A, Wolins NE, Jafari N, Rao MS, Borensztajn J, Yang G, Reddy JK. Transcription coactivator mediator subunit MED1 is required for the development of fatty liver in the mouse. Hepatology 2011; 53:1164-74. [PMID: 21480322 PMCID: PMC3076129 DOI: 10.1002/hep.24155] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
UNLABELLED Peroxisome proliferator-activated receptor-γ (PPARγ), a nuclear receptor, when overexpressed in liver stimulates the induction of adipocyte-specific and lipogenesis-related genes and causes hepatic steatosis. We report here that Mediator 1 (MED1; also known as PBP or TRAP220), a key subunit of the Mediator complex, is required for high-fat diet-induced hepatic steatosis as well as PPARγ-stimulated adipogenic hepatic steatosis. Mediator forms the bridge between transcriptional activators and RNA polymerase II. MED1 interacts with nuclear receptors such as PPARγ and other transcriptional activators. Liver-specific MED1 knockout (MED1(ΔLiv) ) mice, when fed a high-fat (60% kcal fat) diet for up to 4 months failed to develop fatty liver. Similarly, MED1(ΔLiv) mice injected with adenovirus-PPARγ (Ad/PPARγ) by tail vein also did not develop fatty liver, whereas mice with MED1 (MED1(fl/fl) ) fed a high-fat diet or injected with Ad/PPARγ developed severe hepatic steatosis. Gene expression profiling and northern blot analyses of Ad/PPARγ-injected mouse livers showed impaired induction in MED1(ΔLiv) mouse liver of adipogenic markers, such as aP2, adipsin, adiponectin, and lipid droplet-associated genes, including caveolin-1, CideA, S3-12, and others. These adipocyte-specific and lipogenesis-related genes are strongly induced in MED1(fl/fl) mouse liver in response to Ad/PPARγ. Re-expression of MED1 using adenovirally-driven MED1 (Ad/MED1) in MED1(ΔLiv) mouse liver restored PPARγ-stimulated hepatic adipogenic response. These studies also demonstrate that disruption of genes encoding other coactivators such as SRC-1, PRIC285, PRIP, and PIMT had no effect on hepatic adipogenesis induced by PPARγ overexpression. CONCLUSION We conclude that transcription coactivator MED1 is required for high-fat diet-induced and PPARγ-stimulated fatty liver development, which suggests that MED1 may be considered a potential therapeutic target for hepatic steatosis. (HEPATOLOGY 2011;).
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Affiliation(s)
- Liang Bai
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
,Laboratory of Animal Fat Deposition and Muscle Development, College of Animal Science and Technology, Northwest A & F University, Shaanxi 712100, China
| | - Yuzhi Jia
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Navin Viswakarma
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jiansheng Huang
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Aurore Vluggens
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Nathan E. Wolins
- Center for Human Nutrition, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110
| | - Nadereh Jafari
- Genomics Core Facility Center for Genetic Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - M. Sambasiva Rao
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jayme Borensztajn
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Gongshe Yang
- Laboratory of Animal Fat Deposition and Muscle Development, College of Animal Science and Technology, Northwest A & F University, Shaanxi 712100, China
| | - Janardan K. Reddy
- Department of Pathology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Jirasko V, Montserret R, Lee JY, Gouttenoire J, Moradpour D, Penin F, Bartenschlager R. Structural and functional studies of nonstructural protein 2 of the hepatitis C virus reveal its key role as organizer of virion assembly. PLoS Pathog 2010; 6:e1001233. [PMID: 21187906 PMCID: PMC3002993 DOI: 10.1371/journal.ppat.1001233] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Accepted: 11/16/2010] [Indexed: 12/16/2022] Open
Abstract
Non-structural protein 2 (NS2) plays an important role in hepatitis C virus (HCV) assembly, but neither the exact contribution of this protein to the assembly process nor its complete structure are known. In this study we used a combination of genetic, biochemical and structural methods to decipher the role of NS2 in infectious virus particle formation. A large panel of NS2 mutations targeting the N-terminal membrane binding region was generated. They were selected based on a membrane topology model that we established by determining the NMR structures of N-terminal NS2 transmembrane segments. Mutants affected in virion assembly, but not RNA replication, were selected for pseudoreversion in cell culture. Rescue mutations restoring virus assembly to various degrees emerged in E2, p7, NS3 and NS2 itself arguing for an interaction between these proteins. To confirm this assumption we developed a fully functional JFH1 genome expressing an N-terminally tagged NS2 demonstrating efficient pull-down of NS2 with p7, E2 and NS3 and, to a lower extent, NS5A. Several of the mutations blocking virus assembly disrupted some of these interactions that were restored to various degrees by those pseudoreversions that also restored assembly. Immunofluorescence analyses revealed a time-dependent NS2 colocalization with E2 at sites close to lipid droplets (LDs) together with NS3 and NS5A. Importantly, NS2 of a mutant defective in assembly abrogates NS2 colocalization around LDs with E2 and NS3, which is restored by a pseudoreversion in p7, whereas NS5A is recruited to LDs in an NS2-independent manner. In conclusion, our results suggest that NS2 orchestrates HCV particle formation by participation in multiple protein-protein interactions required for their recruitment to assembly sites in close proximity of LDs.
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Affiliation(s)
- Vlastimil Jirasko
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
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45
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Faleck DM, Ali K, Roat R, Graham MJ, Crooke RM, Battisti R, Garcia E, Ahima RS, Imai Y. Adipose differentiation-related protein regulates lipids and insulin in pancreatic islets. Am J Physiol Endocrinol Metab 2010; 299:E249-57. [PMID: 20484013 PMCID: PMC2928510 DOI: 10.1152/ajpendo.00646.2009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The excess accumulation of lipids in islets is thought to contribute to the development of diabetes in obesity by impairing beta-cell function. However, lipids also serve a nutrient function in islets, and fatty acids acutely increase insulin secretion. A better understanding of lipid metabolism in islets will shed light on complex effects of lipids on beta-cells. Adipose differentiation-related protein (ADFP) is localized on the surface of lipid droplets in a wide range of cells and plays an important role in intracellular lipid metabolism. We found that ADFP was highly expressed in murine beta-cells. Moreover, islet ADFP was increased in mice on a high-fat diet (3.5-fold of control) and after fasting (2.5-fold of control), revealing dynamic changes in ADFP in response to metabolic cues. ADFP expression was also increased by addition of fatty acids in human islets. The downregulation of ADFP in MIN6 cells by antisense oligonucleotide (ASO) suppressed the accumulation of triglycerides upon fatty acid loading (56% of control) along with a reduction in the mRNA levels of lipogenic genes such as diacylglycerol O-acyltransferase-2 and fatty acid synthase. Fatty acid uptake, oxidation, and lipolysis were also reduced by downregulation of ADFP. Moreover, the reduction of ADFP impaired the ability of palmitate to increase insulin secretion. These findings demonstrate that ADFP is important in regulation of lipid metabolism and insulin secretion in beta-cells.
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Affiliation(s)
- D. M. Faleck
- 1Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania;
| | - K. Ali
- 1Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania;
| | - R. Roat
- 1Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania;
| | - M. J. Graham
- 2Isis Pharmaceuticals, Carlsbad, California; and
| | - R. M. Crooke
- 2Isis Pharmaceuticals, Carlsbad, California; and
| | - R. Battisti
- 3Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, Norfolk, Virginia
| | - E. Garcia
- 3Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, Norfolk, Virginia
| | - R. S. Ahima
- 1Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania;
| | - Y. Imai
- 1Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania;
- 3Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, Norfolk, Virginia
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Straub BK, Herpel E, Singer S, Zimbelmann R, Breuhahn K, Macher-Goeppinger S, Warth A, Lehmann-Koch J, Longerich T, Heid H, Schirmacher P. Lipid droplet-associated PAT-proteins show frequent and differential expression in neoplastic steatogenesis. Mod Pathol 2010; 23:480-92. [PMID: 20081801 DOI: 10.1038/modpathol.2009.191] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In many human cancers, lipogenic pathways are activated; in some tumors, such as hepatocellular carcinoma, this is reflected by the presence of visible lipid droplets. Yet, the biology of steatogenesis in malignant tumors is largely unknown. We have recently shown that lipid droplet-associated proteins of the PAT-family, named after their constituents perilipin (perilipin 1), adipophilin (perilipin 2), and TIP47 (perilipin 3) are differentially expressed in hepatic steatogenesis. We have comprehensively investigated PAT-expression in neoplastic steatogenesis as well as in respective normal tissues with immunohistology and electron microscopy as well as protein biochemical and molecular biological methods. By staining for PAT-proteins, we found lipid droplet accumulation to be a frequent phenomenon of carcinoma cells. Although adipophilin and TIP47 stained almost ubiquitously the rim of lipid droplets in various tumor types, especially those with clear cell phenotype, perilipin was restricted to lipid droplets of hepatocellular adenoma and carcinoma, sebaceous adenoma and carcinoma, and lipomatous tumors. In hepatocellular carcinoma, perilipin, adipophilin, and TIP47 were coexpressed, and showed regional heterogeneity with a predominantly mutually exclusive localization pattern. In step-wise carcinogenesis, adipophilin expression correlated with the proliferation rate and was upregulated during early tumorigenesis, whereas perilipin was often lost during hepatocarcinogenesis. In conclusion, expression analysis of PAT-proteins showed that by far more carcinomas contain (PAT-positive) lipid droplets than expected by conventional light microscopy. PAT-proteins, such as perilipin, are differentially expressed in different tumor types and thus may support diagnostic considerations. Because inhibition of lipogenesis has been shown to exert antineoplastic effects, PAT-proteins may represent targets for interventive strategies.
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Affiliation(s)
- Beate K Straub
- Department of General Pathology, Institute of Pathology, University Clinic Heidelberg, Heidelberg, Germany.
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