1
|
Jin H, Han H, Song G, Oh HJ, Lee BY. Anti-Obesity Effects of GABA in C57BL/6J Mice with High-Fat Diet-Induced Obesity and 3T3-L1 Adipocytes. Int J Mol Sci 2024; 25:995. [PMID: 38256069 PMCID: PMC10815605 DOI: 10.3390/ijms25020995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/24/2024] Open
Abstract
Obesity is the excessive accumulation of body fat resulting from impairment in energy balance mechanisms. In this study, we aimed to investigate the mechanism whereby GABA (γ-aminobutyric acid) prevents high-fat diet-induced obesity, and whether it induces lipolysis and browning in white adipose tissue (WAT), using high-fat diet (HFD)-fed obese mice and 3T3-L1 adipocytes. We demonstrated that GABA substantially inhibits the body mass gain of mice by suppressing adipogenesis and lipogenesis. Consistent with this result, histological analysis of WAT demonstrated that GABA decreases adipocyte size. Moreover, we show that GABA administration decreases fasting blood glucose and improves serum lipid profiles and hepatic lipogenesis in HFD-fed obese mice. Furthermore, Western blot and immunofluorescence analyses showed that GABA activates protein kinase A (PKA) signaling pathways that increase lipolysis and promote uncoupling protein 1 (UCP1)-mediated WAT browning. Overall, these results suggest that GABA exerts an anti-obesity effect via the regulation of lipid metabolism.
Collapse
Affiliation(s)
| | | | | | | | - Boo-Yong Lee
- Department of Food Science and Biotechnology, College of Life Science, CHA University, Seongnam 13488, Republic of Korea; (H.J.); (H.H.); (G.S.); (H.-J.O.)
| |
Collapse
|
2
|
Zhao X, Amevor FK, Cui Z, Wan Y, Xue X, Peng C, Li Y. Steatosis in metabolic diseases: A focus on lipolysis and lipophagy. Biomed Pharmacother 2023; 160:114311. [PMID: 36764133 DOI: 10.1016/j.biopha.2023.114311] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/23/2023] [Accepted: 01/26/2023] [Indexed: 02/11/2023] Open
Abstract
Fatty acids (FAs), as part of lipids, are involved in cell membrane composition, cellular energy storage, and cell signaling. FAs can also be toxic when their concentrations inside and/or outside the cell exceed physiological levels, which is called "lipotoxicity", and steatosis is a form of lipotoxity. To facilitate the storage of large quantities of FAs in cells, they undergo a process called lipolysis or lipophagy. This review focuses on the effects of lipolytic enzymes including cytoplasmic "neutral" lipolysis, lysosomal "acid" lipolysis, and lipophagy. Moreover, the impact of related lipolytic enzymes on lipid metabolism homeostasis and energy conservation, as well as their role in lipid-related metabolic diseases. In addition, we describe how they affect lipid metabolism homeostasis and energy conservation in lipid-related metabolic diseases with a focus on hepatic steatosis and cancer and the pathogenesis and therapeutic targets of AMPK/SIRTs/FOXOs, PI3K/Akt, PPARs/PGC-1α, MAPK/ERK1/2, TLR4/NF-κB, AMPK/mTOR/TFEB, Wnt/β-catenin through immune inflammation, oxidative stress and autophagy-related pathways. As well as the current application of lipolytic enzyme inhibitors (especially Monoacylglycerol lipase (MGL) inhibitors) to provide new strategies for future exploration of metabolic programming in metabolic diseases.
Collapse
Affiliation(s)
- Xingtao Zhao
- State Key Laboratory of Southwestern Chinese Medicine Resources, Ministry of Education, Chengdu 611137, China; School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
| | - Felix Kwame Amevor
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China.
| | - Zhifu Cui
- College of Animal Science and Technology, Southwest University, Chongqing 400715, China.
| | - Yan Wan
- State Key Laboratory of Southwestern Chinese Medicine Resources, Ministry of Education, Chengdu 611137, China; School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
| | - Xinyan Xue
- State Key Laboratory of Southwestern Chinese Medicine Resources, Ministry of Education, Chengdu 611137, China; School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
| | - Cheng Peng
- State Key Laboratory of Southwestern Chinese Medicine Resources, Ministry of Education, Chengdu 611137, China; School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
| | - Yunxia Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, Ministry of Education, Chengdu 611137, China; School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China.
| |
Collapse
|
3
|
Li S, Zhao Z, Li Q, Li J, Pang Y. Lamprey Wound Healing and Regenerative Effects: The Collaborative Efforts of Diverse Drivers. Int J Mol Sci 2023; 24:ijms24043213. [PMID: 36834626 PMCID: PMC9965152 DOI: 10.3390/ijms24043213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/08/2023] [Accepted: 01/17/2023] [Indexed: 02/10/2023] Open
Abstract
Skin is a natural barrier between the body and the external environment, and this important multifunctional organ plays roles in body temperature regulation, sensory stimulation, mucus secretion, metabolite excretion and immune defense. Lampreys, as ancient vertebrates, rarely experience infection of damaged skin during farming and efficiently promote skin wound healing. However, the mechanism underlying these wound healing and regenerative effects is unclear. Our histology and transcriptomics results demonstrate that lampreys regenerate a nearly complete skin structure in damaged epidermis, including the secretory glands, and will almost not be infected, even if experiencing full-thickness damage. In addition, ATGL, DGL and MGL participate in the lipolysis process to provide space for infiltrating cells. A large number of red blood cells migrate to the site of injury and exert proinflammatory effects, upregulating the expression of proinflammatory factors such as IL-8 and IL-17. Based on a lamprey skin damage healing model, adipocytes and red blood cells in the subcutaneous fat layer can promote wound healing, which provides a new approach for the study of skin healing mechanisms. Transcriptome data reveal that mechanical signal transduction pathways are mainly regulated by focal adhesion kinase and that the actin cytoskeleton plays an important role in the healing of lamprey skin injuries. We identified RAC1 as a key regulatory gene that is necessary and partially sufficient for wound regeneration. Insights into the mechanisms of lamprey skin injury and healing will provide a theoretical basis for overcoming the challenges associated with chronic healing and scar healing in the clinic.
Collapse
Affiliation(s)
- Shushen Li
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China
- Lamprey Research Center, Liaoning Normal University, Dalian 116081, China
| | - Zhiyuan Zhao
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China
- Lamprey Research Center, Liaoning Normal University, Dalian 116081, China
| | - Qingwei Li
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China
- Lamprey Research Center, Liaoning Normal University, Dalian 116081, China
| | - Jun Li
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China
- Lamprey Research Center, Liaoning Normal University, Dalian 116081, China
- Correspondence: (J.L.); (Y.P.)
| | - Yue Pang
- College of Life Sciences, Liaoning Normal University, Dalian 116081, China
- Lamprey Research Center, Liaoning Normal University, Dalian 116081, China
- Correspondence: (J.L.); (Y.P.)
| |
Collapse
|
4
|
Xiao Z, Liu M, Yang F, Liu G, Liu J, Zhao W, Ma S, Duan Z. Programmed cell death and lipid metabolism of macrophages in NAFLD. Front Immunol 2023; 14:1118449. [PMID: 36742318 PMCID: PMC9889867 DOI: 10.3389/fimmu.2023.1118449] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 01/06/2023] [Indexed: 01/19/2023] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) has now become the leading chronic liver disease worldwide with lifestyle changes. This may lead to NAFLD becoming the leading cause of end-stage liver disease in the future. To date, there are still no effective therapeutic drugs for NAFLD. An in-depth exploration of the pathogenesis of NAFLD can help to provide a basis for new therapeutic agents or strategies. As the most important immune cells of the liver, macrophages play an important role in the occurrence and development of liver inflammation and are expected to become effective targets for NAFLD treatment. Programmed cell death (PCD) of macrophages plays a regulatory role in phenotypic transformation, and there is also a certain connection between different types of PCD. However, how PCD regulates macrophage polarization has still not been systematically elucidated. Based on the role of lipid metabolic reprogramming in macrophage polarization, PCD may alter the phenotype by regulating lipid metabolism. We reviewed the effects of macrophages on inflammation in NAFLD and changes in their lipid metabolism, as well as the relationship between different types of PCD and lipid metabolism in macrophages. Furthermore, interactions between different types of PCD and potential therapeutic agents targeting of macrophages PCD are also explored.
Collapse
Affiliation(s)
- Zhun Xiao
- Department of Digestive Diseases, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China
| | - Minghao Liu
- Department of Digestive Diseases, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China
| | - Fangming Yang
- Department of Digestive Diseases, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China
| | - Guangwei Liu
- Department of Digestive Diseases, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China
| | - Jiangkai Liu
- Department of Digestive Diseases, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China
| | - Wenxia Zhao
- Department of Digestive Diseases, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China
| | - Suping Ma
- Department of Digestive Diseases, The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, China,*Correspondence: Suping Ma, ; Zhongping Duan,
| | - Zhongping Duan
- Beijing Institute of Hepatology, Beijing Youan Hospital Capital Medical University, Beijing, China,*Correspondence: Suping Ma, ; Zhongping Duan,
| |
Collapse
|
5
|
Xue Y, Zhu X, Yan W, Zhang Z, Cui E, Wu Y, Li C, Pan J, Yan Q, Chai X, Zhao S. Dietary Supplementation With Acer truncatum Oil Promotes Remyelination in a Mouse Model of Multiple Sclerosis. Front Neurosci 2022; 16:860280. [PMID: 35585921 PMCID: PMC9109879 DOI: 10.3389/fnins.2022.860280] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
Background Multiple sclerosis is a chronic demyelinating disease of uncertain etiology. Traditional treatment methods produce more adverse effects. Epidemiological and clinical treatment findings showed that unknown environmental factors contribute to the etiology of MS and that diet is a commonly assumed factor. Despite the huge interest in diet expressed by people with MS and the potential role diet plays in MS, very little data is available on the role of diet in MS pathogenesis and MS course, in particular, studies on fats and MS. The oil of Acer truncatum is potential as a resource to be exploited in the treatment of some neurodegenerative diseases. Objective Here, we investigated the underlying influences of Acer truncatum oil on the stimulation of remyelination in a cuprizone mouse model of demyelination. Methods Cuprizone (0.2% in chow) was used to establish a mouse model of demyelination. Acer truncatum oil was administrated to mice during remyelination. Following techniques were used: behavioral test, histochemistry, fluorescent immunohistochemistry, transmission electron microscope. Results Mice exposed to cuprizone for 6 weeks showed schizophrenia-like behavioral changes, the increased exploration of the center in the open field test (OFT), increased entries into the open arms of the elevated plus-maze, as well as demyelination in the corpus callosum. After cuprizone withdrawal, the diet therapy was initiated with supplementation of Acer truncatum oil for 2 weeks. As expected, myelin repair was greatly enhanced in the demyelinated regions with increased mature oligodendrocytes (CC1) and myelin basic protein (MBP). More importantly, the supplementation with Acer truncatum oil in the diet reduced the schizophrenia-like behavior in the open field test (OFT) and the elevated plus-maze compared to the cuprizone recovery group. The results revealed that the diet supplementation with Acer truncatum oil improved behavioral abnormalities, oligodendrocyte maturation, and remyelination in the cuprizone model during recovery. Conclusion Diet supplementation with Acer truncatum oil attenuates demyelination induced by cuprizone, indicating that Acer truncatum oil is a novel therapeutic diet in demyelinating diseases.
Collapse
Affiliation(s)
- Yuhuan Xue
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Xiaoyan Zhu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Wenyong Yan
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Zhihan Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Enhui Cui
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yongji Wu
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Cixia Li
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Jiarong Pan
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Qijiang Yan
- Multiple Sclerosis Research Center of New York, New York, NY, United States
| | - Xuejun Chai
- Department of Basic Medicine, Xi’an Medical University, Xi’an, China
| | - Shanting Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| |
Collapse
|
6
|
Dixon ED, Nardo AD, Claudel T, Trauner M. The Role of Lipid Sensing Nuclear Receptors (PPARs and LXR) and Metabolic Lipases in Obesity, Diabetes and NAFLD. Genes (Basel) 2021; 12:genes12050645. [PMID: 33926085 PMCID: PMC8145571 DOI: 10.3390/genes12050645] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/23/2021] [Accepted: 04/23/2021] [Indexed: 12/11/2022] Open
Abstract
Obesity and type 2 diabetes mellitus (T2DM) are metabolic disorders characterized by metabolic inflexibility with multiple pathological organ manifestations, including non-alcoholic fatty liver disease (NAFLD). Nuclear receptors are ligand-dependent transcription factors with a multifaceted role in controlling many metabolic activities, such as regulation of genes involved in lipid and glucose metabolism and modulation of inflammatory genes. The activity of nuclear receptors is key in maintaining metabolic flexibility. Their activity depends on the availability of endogenous ligands, like fatty acids or oxysterols, and their derivatives produced by the catabolic action of metabolic lipases, most of which are under the control of nuclear receptors. For example, adipose triglyceride lipase (ATGL) is activated by peroxisome proliferator-activated receptor γ (PPARγ) and conversely releases fatty acids as ligands for PPARα, therefore, demonstrating the interdependency of nuclear receptors and lipases. The diverse biological functions and importance of nuclear receptors in metabolic syndrome and NAFLD has led to substantial effort to target them therapeutically. This review summarizes recent findings on the roles of lipases and selected nuclear receptors, PPARs, and liver X receptor (LXR) in obesity, diabetes, and NAFLD.
Collapse
Affiliation(s)
| | | | | | - Michael Trauner
- Correspondence: ; Tel.: +43-140-4004-7410; Fax: +43-14-0400-4735
| |
Collapse
|
7
|
Pelizzaro F, Kitenge MP, Cardin R, Ponzoni A, Cillo U, Vitale A, Businello G, Munari G, Fassan M, Farinati F. Circulating prostaglandin E 2: a novel potential prognostic biomarker in patients with hepatocellular carcinoma. Clin Exp Med 2021; 21:675-682. [PMID: 33768340 DOI: 10.1007/s10238-021-00705-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 03/17/2021] [Indexed: 02/07/2023]
Abstract
We aimed to explore the activation of monoacylglycerol lipase (MAGL)/cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) axis in hepatocellular carcinoma (HCC), evaluating circulating PGE2 as prognostic biomarker in HCC patients. PGE2 levels were measured in blood samples from 24 cirrhotics, and 34 HCC patients were consecutively collected between January 2016 and December 2017. In a subgroup of patients, tissue expression of MAGL mRNA and immunohistochemistry for MAGL and COX-2 were obtained. Despite tumor tissues showing overexpression of MAGL mRNA and higher levels of both MAGL and COX-2 at immunohistochemistry, PGE2 levels were not significantly different in HCC and cirrhotics. HCC patients with circulating PGE2 levels > 14 pg/mL had a significantly shorter overall survival (19.4 vs. 49.9 months; p = 0.03), the finding being confirmed by the multivariate analysis (HR 3.37 [95% CI 1.00-11.60]; p = 0.05). The MAGL/COX-2/PGE2 axis is activated in HCC, and circulating PGE2 proved to be a potential prognostic biomarker.
Collapse
Affiliation(s)
- Filippo Pelizzaro
- Gastroenterology Unit, Oncology and Gastroenterology, Department of Surgery, University of Padova, Padova, Italy
| | - Maria Piera Kitenge
- Gastroenterology Unit, Oncology and Gastroenterology, Department of Surgery, University of Padova, Padova, Italy
| | - Romilda Cardin
- Gastroenterology Unit, Oncology and Gastroenterology, Department of Surgery, University of Padova, Padova, Italy
| | - Alberto Ponzoni
- Radiology Unit, Azienda-Ospedale Università Di Padova, Padova, Italy
| | - Umberto Cillo
- Hepatobiliary Surgery and Liver Transplantation Unit, Oncology and Gastroenterology, Department of Surgery, University of Padova, Padova, Italy
| | - Alessandro Vitale
- Hepatobiliary Surgery and Liver Transplantation Unit, Oncology and Gastroenterology, Department of Surgery, University of Padova, Padova, Italy
| | - Gianluca Businello
- Surgical Pathology and Cytopathology Unit, Department of Medicine (DIMED), University of Padova, Padova, Italy
| | - Giada Munari
- Surgical Pathology and Cytopathology Unit, Department of Medicine (DIMED), University of Padova, Padova, Italy
| | - Matteo Fassan
- Surgical Pathology and Cytopathology Unit, Department of Medicine (DIMED), University of Padova, Padova, Italy
| | - Fabio Farinati
- Gastroenterology Unit, Oncology and Gastroenterology, Department of Surgery, University of Padova, Padova, Italy.
| |
Collapse
|
8
|
Tardelli M, Bruschi FV, Fuchs CD, Claudel T, Auer N, Kunczer V, Ronda OAHO, Verkade HJ, Stojakovic T, Scharnagl H, Trauner M. Absence of Adiponutrin (PNPLA3) and Monoacylglycerol Lipase Synergistically Increases Weight Gain and Aggravates Steatohepatitis in Mice. Int J Mol Sci 2021; 22:2126. [PMID: 33672787 PMCID: PMC7924608 DOI: 10.3390/ijms22042126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 01/29/2021] [Accepted: 02/02/2021] [Indexed: 12/11/2022] Open
Abstract
Altered lipid metabolic pathways including hydrolysis of triglycerides are key players in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). Whether adiponutrin (patatin-like phospholipase domain containing protein-3-PNPLA3) and monoacylglycerol lipase (MGL) synergistically contribute to disease progression remains unclear. We generated double knockout (DKO) mice lacking both Mgl and Pnpla3; DKO mice were compared to Mgl-/- after a challenge by high-fat diet (HFD) for 12 weeks to induce steatosis. Serum biochemistry, liver transaminases as well as histology were analyzed. Fatty acid (FA) profiling was assessed in liver and adipose tissue by gas chromatography. Markers of inflammation and lipid metabolism were analyzed. Bone marrow derived macrophages (BMDMs) were isolated and treated with oleic acid. Combined deficiency of Mgl and Pnpla3 resulted in weight gain on a chow diet; when challenged by HFD, DKO mice showed increased hepatic FA synthesis and diminished beta-oxidation compared to Mgl-/-.DKO mice exhibited more pronounced hepatic steatosis with inflammation and recruitment of immune cells to the liver associated with accumulation of saturated FAs. Primary BMDMs isolated from the DKO mice showed increased inflammatory activities, which could be reversed by oleic acid supplementation. Pnpla3 deficiency aggravates the effects of Mgl deletion on steatosis and inflammation in the liver under HFD challenge.
Collapse
Affiliation(s)
- Matteo Tardelli
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria; (M.T.); (F.V.B.); (C.D.F.); (T.C.); (N.A.); (V.K.)
| | - Francesca V. Bruschi
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria; (M.T.); (F.V.B.); (C.D.F.); (T.C.); (N.A.); (V.K.)
| | - Claudia D. Fuchs
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria; (M.T.); (F.V.B.); (C.D.F.); (T.C.); (N.A.); (V.K.)
| | - Thierry Claudel
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria; (M.T.); (F.V.B.); (C.D.F.); (T.C.); (N.A.); (V.K.)
| | - Nicole Auer
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria; (M.T.); (F.V.B.); (C.D.F.); (T.C.); (N.A.); (V.K.)
| | - Victoria Kunczer
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria; (M.T.); (F.V.B.); (C.D.F.); (T.C.); (N.A.); (V.K.)
| | - Onne A. H. O. Ronda
- Center for Liver, Digestive and Metabolic Diseases, Departments of Pediatrics, University Medical Center Groningen, 9712 Groningen, The Netherlands; (O.A.H.O.R.); (H.J.V.)
| | - Henkjan J. Verkade
- Center for Liver, Digestive and Metabolic Diseases, Departments of Pediatrics, University Medical Center Groningen, 9712 Groningen, The Netherlands; (O.A.H.O.R.); (H.J.V.)
| | - Tatjana Stojakovic
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, University Hospital Graz, 8036 Graz, Austria;
| | - Hubert Scharnagl
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, 8036 Graz, Austria;
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, 1090 Vienna, Austria; (M.T.); (F.V.B.); (C.D.F.); (T.C.); (N.A.); (V.K.)
| |
Collapse
|
9
|
Mashek DG. Hepatic lipid droplets: A balancing act between energy storage and metabolic dysfunction in NAFLD. Mol Metab 2020; 50:101115. [PMID: 33186758 PMCID: PMC8324678 DOI: 10.1016/j.molmet.2020.101115] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 10/21/2020] [Accepted: 11/06/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is defined by the abundance of lipid droplets (LDs) in hepatocytes. While historically considered simply depots for energy storage, LDs are increasingly recognized to impact a wide range of biological processes that influence cellular metabolism, signaling, and function. While progress has been made toward understanding the factors leading to LD accumulation (i.e. steatosis) and its progression to advanced stages of NAFLD and/or systemic metabolic dysfunction, much remains to be resolved. SCOPE OF REVIEW This review covers many facets of LD biology. We provide a brief overview of the major pathways of lipid accretion and degradation that contribute to steatosis and how they are altered in NAFLD. The major focus is on the relationship between LDs and cell function and the detailed mechanisms that couple or uncouple steatosis from the severity and progression of NAFLD and systemic comorbidities. The importance of specific lipids and proteins within or on LDs as key components that determine whether LD accumulation is linked to cellular and metabolic dysfunction is presented. We discuss emerging areas of LD biology and future research directions that are needed to advance our understanding of the role of LDs in NAFLD etiology. MAJOR CONCLUSIONS Impairments in LD breakdown appear to contribute to disease progression, but inefficient incorporation of fatty acids (FAs) into LD-containing triacylglycerol (TAG) and the consequential changes in FA partitioning also affect NAFLD etiology. Increased LD abundance in hepatocytes does not necessarily equate to cellular dysfunction. While LD accumulation is the prerequisite step for most NAFLD cases, the protein and lipid composition of LDs are critical factors in determining the progression from simple steatosis. Further defining the detailed molecular mechanisms linking LDs to metabolic dysfunction is important for designing effective therapeutic approaches targeting NAFLD and its comorbidities.
Collapse
Affiliation(s)
- Douglas G Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, University of Minnesota, Suite 6-155, 321 Church St. SE, Minneapolis, MN, 55455, USA.
| |
Collapse
|