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Drummer DJ, Lavin KM, Graham ZA, O'Bryan SM, McAdam JS, Lixandrão ME, Seay R, Aban I, Siegel HJ, Ghanem E, Singh JA, Bonfitto A, Antone J, Reiman R, Hutchins E, Van Keuren-Jensen K, Schutzler SE, Barnes CL, Ferrando AA, Bridges SL, Bamman MM. Muscle transcriptomic circuits linked to periarticular physiology in end-stage osteoarthritis. Physiol Genomics 2022; 54:501-513. [PMID: 36278270 PMCID: PMC9762959 DOI: 10.1152/physiolgenomics.00092.2022] [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: 06/10/2022] [Revised: 09/08/2022] [Accepted: 10/20/2022] [Indexed: 02/01/2023] Open
Abstract
The ability of individuals with end-stage osteoarthritis (OA) to functionally recover from total joint arthroplasty is highly inconsistent. The molecular mechanisms driving this heterogeneity have yet to be elucidated. Furthermore, OA disproportionately impacts females, suggesting a need for identifying female-specific therapeutic targets. We profiled the skeletal muscle transcriptome in females with end-stage OA (n = 20) undergoing total knee or hip arthroplasty using RNA-Seq. Single-gene differential expression (DE) analyses tested for DE genes between skeletal muscle overlaying the surgical (SX) joint and muscle from the contralateral (CTRL) leg. Network analyses were performed using Pathway-Level Information ExtractoR (PLIER) to summarize genes into latent variables (LVs), i.e., gene circuits, and link them to biological pathways. LV differences in SX versus CTRL muscle and across sources of muscle tissue (vastus medialis, vastus lateralis, or tensor fascia latae) were determined with ANOVA. Linear models tested for associations between LVs and muscle phenotype on the SX side (inflammation, function, and integrity). DE analysis revealed 360 DE genes (|Log2 fold-difference| ≥ 1, FDR ≤ 0.05) between the SX and CTRL limbs, many associated with inflammation and lipid metabolism. PLIER analyses revealed circuits associated with protein degradation and fibro-adipogenic cell gene expression. Muscle inflammation and function were linked to an LV associated with endothelial cell gene expression highlighting a potential regulatory role of endothelial cells within skeletal muscle. These findings may provide insight into potential therapeutic targets to improve OA rehabilitation before and/or following total joint replacement.
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Affiliation(s)
- Devin J Drummer
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Kaleen M Lavin
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Florida Institute for Human and Machine Cognition, Pensacola, Florida
| | - Zachary A Graham
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Florida Institute for Human and Machine Cognition, Pensacola, Florida
- Birmingham VA Medical Center, Birmingham, Alabama
| | - Samia M O'Bryan
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jeremy S McAdam
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Florida Institute for Human and Machine Cognition, Pensacola, Florida
| | - Manoel E Lixandrão
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado
| | - Regina Seay
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Inmaculada Aban
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama
| | - Herrick J Siegel
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Orthopaedic Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Elie Ghanem
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Orthopaedic Surgery, University of Alabama at Birmingham, Birmingham, Alabama
| | - Jasvinder A Singh
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Birmingham VA Medical Center, Birmingham, Alabama
- Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Comprehensive Arthritis, Musculoskeletal, Bone, and Autoimmunity Center, University of Alabama at Birmingham, Birmingham, Alabama
| | - Anna Bonfitto
- Division of Neurogenomics, The Translational Genomics Research Institute, Phoenix, Arizona
| | - Jerry Antone
- Division of Neurogenomics, The Translational Genomics Research Institute, Phoenix, Arizona
| | - Rebecca Reiman
- Division of Neurogenomics, The Translational Genomics Research Institute, Phoenix, Arizona
| | - Elizabeth Hutchins
- Division of Neurogenomics, The Translational Genomics Research Institute, Phoenix, Arizona
| | | | - Scott E Schutzler
- Department of Geriatrics and Center for Translational Research in Aging and Longevity, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - C Lowry Barnes
- Department of Orthopaedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Arny A Ferrando
- Department of Geriatrics and Center for Translational Research in Aging and Longevity, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - S Louis Bridges
- Department of Medicine, Hospital for Special Surgery, New York, New York
- Division of Rheumatology, Weill Cornell Medical Center, New York, New York
| | - Marcas M Bamman
- UAB Center for Exercise Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Florida Institute for Human and Machine Cognition, Pensacola, Florida
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Zhang N, Peng Y, Zhao L, He P, Zhu J, Liu Y, Liu X, Liu X, Deng G, Zhang Z, Feng M. Integrated Analysis of Gut Microbiome and Lipid Metabolism in Mice Infected with Carbapenem-Resistant Enterobacteriaceae. Metabolites 2022; 12:metabo12100892. [PMID: 36295794 PMCID: PMC9609999 DOI: 10.3390/metabo12100892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 09/15/2022] [Accepted: 09/16/2022] [Indexed: 11/22/2022] Open
Abstract
The disturbance in gut microbiota composition and metabolism has been implicated in the process of pathogenic bacteria infection. However, the characteristics of the microbiota and the metabolic interaction of commensals−host during pathogen invasion remain more than vague. In this study, the potential associations of gut microbes with disturbed lipid metabolism in mice upon carbapenem-resistant Escherichia coli (CRE) infection were explored by the biochemical and multi-omics approaches including metagenomics, metabolomics and lipidomics, and then the key metabolites−reaction−enzyme−gene interaction network was constructed. Results showed that intestinal Erysipelotrichaceae family was strongly associated with the hepatic total cholesterol and HDL-cholesterol, as well as a few sera and fecal metabolites involved in lipid metabolism such as 24, 25-dihydrolanosterol. A high-coverage lipidomic analysis further demonstrated that a total of 529 lipid molecules was significantly enriched and 520 were depleted in the liver of mice infected with CRE. Among them, 35 lipid species showed high correlations (|r| > 0.8 and p < 0.05) with the Erysipelotrichaceae family, including phosphatidylglycerol (42:2), phosphatidylglycerol (42:3), phosphatidylglycerol (38:5), phosphatidylcholine (42:4), ceramide (d17:1/16:0), ceramide (d18:1/16:0) and diacylglycerol (20:2), with correlation coefficients higher than 0.9. In conclusion, the systematic multi-omics study improved the understanding of the complicated connection between the microbiota and the host during pathogen invasion, which thereby is expected to lead to the future discovery and establishment of novel control strategies for CRE infection.
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Affiliation(s)
- Ning Zhang
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center for Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Noncoding RNA, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Yuanyuan Peng
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center for Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Noncoding RNA, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Linjing Zhao
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center for Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Noncoding RNA, Shanghai University of Engineering Science, Shanghai 201620, China
- Correspondence: ; Tel.: +86-21-6779-1214
| | - Peng He
- Minhang Hospital & School of Pharmacy, Fudan University, Shanghai 200433, China
- Shanghai Engineering Research Center of Immunotherapeutic, Shanghai 201203, China
| | - Jiamin Zhu
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center for Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Noncoding RNA, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Yumin Liu
- Instrumental Analysis Centre, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xijian Liu
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center for Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Noncoding RNA, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Xiaohui Liu
- School of Chemistry and Chemical Engineering, Shanghai Engineering Research Center for Pharmaceutical Intelligent Equipment, Shanghai Frontiers Science Research Center for Druggability of Cardiovascular Noncoding RNA, Shanghai University of Engineering Science, Shanghai 201620, China
| | - Guoying Deng
- Trauma Center, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Zhong Zhang
- Nursing Department, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201620, China
| | - Meiqing Feng
- Minhang Hospital & School of Pharmacy, Fudan University, Shanghai 200433, China
- Shanghai Engineering Research Center of Immunotherapeutic, Shanghai 201203, China
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Xie K, Liu Y, Li X, Zhang H, Zhang S, Mak HY, Liu P. Dietary S. maltophilia induces supersized lipid droplets by enhancing lipogenesis and ER-LD contacts in C. elegans. Gut Microbes 2022; 14:2013762. [PMID: 35112996 PMCID: PMC8816401 DOI: 10.1080/19490976.2021.2013762] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Dietary and symbiotic bacteria can exert powerful influence on metazoan lipid metabolism. Recent studies have emerged that microbiota have a role in animal obesity and related health disorders, but the mechanisms by which bacteria influence lipid storage in their host are unknown. To reduce the complexity of the relationship between gut microbiota and the host, Caenorhabditis elegans (C. elegans) has been chosen as a model organism to study interspecies interaction. Here, we demonstrate that feeding C. elegans with an opportunistic pathogenic bacterium Stenotrophomonas maltophilia (S. maltophilia) retards growth and promotes excessive neutral lipid storage. Gene expression analysis reveals that dietary S. maltophilia induces a lipogenic transcriptional response that includes the SREBP ortholog SBP-1, and fatty acid desaturases FAT-6 and FAT-7. Live imaging and ultrastructural analysis suggest that excess neutral lipid is stored in greatly expanded lipid droplets (LDs), as a result of enhanced endoplasmic reticulum (ER)-LD interaction. We also report that loss of function mutations in dpy-9 in C. elegans confers resistance to S. maltophilia. Dietary S. maltophilia induces supersized LDs by enhancing lipogenesis and ER-LD contacts in C. elegans. This work delineates a new model for understanding microbial regulation of metazoan physiology.
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Affiliation(s)
- Kang Xie
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Yangli Liu
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Xixia Li
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Shuyan Zhang
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Ho Yi Mak
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China,CONTACT Pingsheng Liu National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing100101, China
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Sparks LM, Goodpaster BH, Bergman BC. The Metabolic Significance of Intermuscular Adipose Tissue: Is IMAT a Friend or a Foe to Metabolic Health? Diabetes 2021; 70:2457-2467. [PMID: 34711670 DOI: 10.2337/dbi19-0006] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 08/27/2021] [Indexed: 12/25/2022]
Abstract
Adipose tissues are not homogeneous and show site-specific properties. An elusive and understudied adipose tissue depot, most likely due to its limited accessibility, is the intermuscular adipose tissue (IMAT) depot. Adipose tissue is a pliable organ with the ability to adapt to its physiological context, yet whether that adaptation is harmful or beneficial in the IMAT depot remains to be explored in humans. Potential reasons for IMAT accumulation in humans being deleterious or beneficial include 1) sex and related circulating hormone levels, 2) race and ethnicity, and 3) lifestyle factors (e.g., diet and physical activity level). IMAT quantity per se may not be the driving factor in the etiology of insulin resistance and type 2 diabetes, but rather the quality of the IMAT itself is the true puppeteer. Adipose tissue quality likely influences its secreted factors, which are also likely to influence metabolism of surrounding tissues. The advent of molecular assessments such as transcriptome sequencing (RNAseq), assay for transposase-accessible chromatin using sequencing (ATACseq), and DNA methylation at the single-cell and single-nucleus levels, as well as the potential for ultrasound-guided biopsies specifically for IMAT, will permit more sophisticated investigations of human IMAT and dramatically advance our understanding of this enigmatic adipose tissue.
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Turner MC, Rimington RP, Martin NRW, Fleming JW, Capel AJ, Hodson L, Lewis MP. Physiological and pathophysiological concentrations of fatty acids induce lipid droplet accumulation and impair functional performance of tissue engineered skeletal muscle. J Cell Physiol 2021; 236:7033-7044. [PMID: 33738797 DOI: 10.1002/jcp.30365] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 02/11/2021] [Accepted: 03/08/2021] [Indexed: 12/19/2022]
Abstract
Fatty acids (FA) exert physiological and pathophysiological effects leading to changes in skeletal muscle metabolism and function, however, in vitro models to investigate these changes are limited. These experiments sought to establish the effects of physiological and pathophysiological concentrations of exogenous FA upon the function of tissue engineered skeletal muscle (TESkM). Cultured initially for 14 days, C2C12 TESkM was exposed to FA-free bovine serum albumin alone or conjugated to a FA mixture (oleic, palmitic, linoleic, and α-linoleic acids [OPLA] [ratio 45:30:24:1%]) at different concentrations (200 or 800 µM) for an additional 4 days. Subsequently, TESkM morphology, functional capacity, gene expression and insulin signaling were analyzed. There was a dose response increase in the number and size of lipid droplets within the TESkM (p < .05). Exposure to exogenous FA increased the messenger RNA expression of genes involved in lipid storage (perilipin 2 [p < .05]) and metabolism (pyruvate dehydrogenase lipoamide kinase isozyme 4 [p < .01]) in a dose dependent manner. TESkM force production was reduced (tetanic and single twitch) (p < .05) and increases in transcription of type I slow twitch fiber isoform, myosin heavy chain 7, were observed when cultured with 200 µM OPLA compared to control (p < .01). Four days of OPLA exposure results in lipid accumulation in TESkM which in turn results in changes in muscle function and metabolism; thus, providing insight ito the functional and mechanistic changes of TESkM in response to exogenous FA.
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Affiliation(s)
- Mark C Turner
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, UK.,Leicester Biomedical Research Centre, University Hospitals of Leicester NHS Trust, Leicester, UK.,Centre for Sport, Exercise and Life Sciences, Research Institute for Health and Wellbeing, Coventry University, Coventry, UK
| | - Rowan P Rimington
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, UK
| | - Neil R W Martin
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, UK
| | - Jacob W Fleming
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, UK
| | - Andrew J Capel
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, UK
| | - Leanne Hodson
- Oxford Center for Diabetes, Endocrinology and Metabolism, Oxford Biomedical Research Centre, Radcliffe Department of Medicine, Churchill Hospital, University of Oxford, Oxford, UK
| | - Mark P Lewis
- School of Sport, Exercise and Health Sciences, National Centre for Sport and Exercise Medicine, Loughborough University, Loughborough, UK
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Vilela JDMV, Dolmans MM, Maruhashi E, Blackman MCNM, Sonveaux P, Miranda-Vilela AL, Amorim CA. Evidence of metabolic activity during low-temperature ovarian tissue preservation in different media. J Assist Reprod Genet 2020; 37:2477-2486. [PMID: 32885380 PMCID: PMC7550475 DOI: 10.1007/s10815-020-01935-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/25/2020] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Although ovarian tissue transportation has been validated for up to 24 h, there is no standard protocol to date. We aimed to elucidate how existing media currently used for ovarian tissue transportation affect ovarian tissue metabolism and cell viability. METHODS Cow ovarian fragments were immersed in 0.9% NaCl solution, IVF medium, Leibovitz 15 medium (L-15), or PBS for 1, 4, or 24 h at 4 °C. Media were analyzed for pH, lactate dehydrogenase (LDH) activity, and glucose, pyruvate, and lactate concentrations, while apoptosis was assessed by TUNEL assays in fixed fragments. Viability rates were assessed by flow cytometry (FACS). RESULTS There were lower pH levels in NaCl at all time points compared with other media. LDH activity increased with time and was lowest in NaCl at 1 and 4 h. There was no significant difference in glucose levels, but a significant pyruvate decrease in L-15 and a significant lactate increase in all media. TUNEL showed apoptosis rates ranging from 0 to 5%. FACS showed a mean of 4% necrotic cells and 15-19% apoptotic cells after 1 h of incubation, but less than 1% necrotic cells and 2-6% apoptotic cells after 24 h in all media. CONCLUSION Our results indicate marked metabolic activity in ovarian tissue at 4 °C and suggest that cells use internal sources of energy, which may influence transplantation outcomes. This highlights the importance of better understanding whole tissue dynamics to develop a standard protocol for ovarian tissue transportation. Graphical abstract.
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Affiliation(s)
- Janice de M V Vilela
- Pôle de Recherche en Gynécologie, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Avenue Mounier 52, bte B1.52.02, 1200, Brussels, Belgium
| | - Marie-Madeleine Dolmans
- Pôle de Recherche en Gynécologie, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Avenue Mounier 52, bte B1.52.02, 1200, Brussels, Belgium
- Gynecology Department, Cliniques Universitaires Saint Luc, 1200, Brussels, Belgium
| | - Emi Maruhashi
- Pôle de Recherche en Gynécologie, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Avenue Mounier 52, bte B1.52.02, 1200, Brussels, Belgium
| | - Marine C N M Blackman
- Pôle de Pharmacologie et Thérapeutique, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, 1200, Brussels, Belgium
| | - Pierre Sonveaux
- Pôle de Pharmacologie et Thérapeutique, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, 1200, Brussels, Belgium
| | | | - Christiani A Amorim
- Pôle de Recherche en Gynécologie, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Avenue Mounier 52, bte B1.52.02, 1200, Brussels, Belgium.
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Tadano K, Okamoto Y, Isobe T, Mori S, Suzuki H, Minami M, Sakae T. Changes in skeletal muscle diffusion parameters owing to intramyocellular lipid. Magn Reson Imaging 2020; 73:70-75. [PMID: 32853758 DOI: 10.1016/j.mri.2020.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 07/09/2020] [Accepted: 08/14/2020] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Several studies investigated the changes in diffusion of water molecules in skeletal muscle cells of lifestyle-related-disease patients who performed a hybrid training (HYBT) for six months. They reported that the apparent diffusion coefficient (ADC) and all diffusion eigenvalues (λ1, λ2, and λ3) increased after the HYBT, owing to the enlargement of the intramyocellular diffusion space (intracellular space) caused by the muscular hypertrophy. We assumed that the HYBT promoted metabolism of the whole skeletal muscle including lipids, which reduced the amount of intramyocellular lipid (IMCL), and led to a secondary enlargement of the diffusion space in the skeletal muscle cells. However, the IMCL has to be a diffusion limiting factor in order to verify this hypothesis. Until now, there is no report on whether IMCL is a diffusion limiting factor for water molecules. The objective of this study was to examine whether the IMCL is a diffusion limiting factor in skeletal muscle cells. MATERIALS AND METHODS We performed a three-dimensional quantification of the IMCL in triceps surae muscles of lifestyle-related-disease patients and healthy volunteers. In addition, we measured the ADC in the volume of interest (VOI), diffusion anisotropy (FA), and diffusion eigenvalues (λ1, λ2, and λ3), and evaluated the correlations between these diffusion parameters and IMCL. RESULTS The results showed that the amount of IMCL was positively and negatively correlated with the FA and λ3, respectively, in lifestyle-related-disease patients. In addition, there was a weak negative correlation between IMCL and ADC, λ1, and λ2. There was no correlation between the amount of IMCL and diffusion parameters of healthy volunteers. DISCUSSION Above a certain amount, the IMCL correlates with the diffusion parameters. A higher amount of IMCL leads to smaller diffusion eigenvalues. This result suggested that IMCL possibility of influencing diffusion of water molecules in skeletal muscle cells. However, in order for the influence of IMCL to be reflected in the diffusion eigenvalues, it was needed large amount of IMCL existed, and we thought that the influence was smaller than the influence by the already reported cell membrane.
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Affiliation(s)
- Kiichi Tadano
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan; Faculty of Health Sciences, Kyorin University, 5-4-1 Shimorenjaku, Mitaka, Tokyo 181-8612, Japan.
| | - Yoshikazu Okamoto
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Tomonori Isobe
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Shintaro Mori
- Department of Early Childhood Education and Nurture, Tokiwa Junior College, 1-430-1, Miwa Mito, Ibaraki 310-8585, Japan
| | - Hiroaki Suzuki
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Manabu Minami
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
| | - Takeji Sakae
- Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
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8
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Barchuk M, Dutour A, Ancel P, Svilar L, Miksztowicz V, Lopez G, Rubio M, Schreier L, Nogueira JP, Valéro R, Béliard S, Martin JC, Berg G, Gaborit B. Untargeted Lipidomics Reveals a Specific Enrichment in Plasmalogens in Epicardial Adipose Tissue and a Specific Signature in Coronary Artery Disease. Arterioscler Thromb Vasc Biol 2020; 40:986-1000. [PMID: 32102570 DOI: 10.1161/atvbaha.120.313955] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Epicardial adipose tissue (EAT) is an active endocrine organ that could contribute to the pathophysiology of coronary artery disease (CAD) through the paracrine release of proatherogenic mediators. Numerous works have analyzed the inflammatory signature of EAT, but scarce informations on its lipidome are available. Our objective was first to study the differences between EAT and subcutaneous adipose tissue (SAT) lipidomes and second to identify the specific untargeted lipidomic signatures of EAT and SAT in CAD. Approach and Results: Subcutaneous and EAT untargeted lipidomic analysis was performed in 25 patients with CAD and 14 patients without CAD and compared with paired plasma lipidomic analysis of isolated VLDL (very low-density lipoprotein) and HDL (high-density lipoprotein). Lipidomics was performed on a C18 column hyphenated to a Q-Exactive plus mass spectrometer, using both positive and negative ionization mode. EAT and SAT had independent lipidomic profile, with 95 lipid species differentially expressed and phosphatidylethanolamine 18:1p/22:6 twenty-fold more expressed in EAT compared with SAT false discovery rate =3×10-4). Patients with CAD exhibited more ceramides (P=0.01), diglycerides (P=0.004; saturated and nonsaturated), monoglycerides (P=0.013) in their EAT than patients without CAD. Conversely, they had lesser unsaturated TG (triglycerides; P=0.02). No difference was observed in the 295 lipid species found in SAT between patients with and without CAD. Fifty-one lipid species were found in common between EAT and plasma lipoproteins. TG 18:0/18:0/18:1 was found positively correlated (r=0.45, P=0.019) in EAT and HDL and in EAT and VLDL (r=0.46, P=0.02). CONCLUSIONS CAD is associated with specific lipidomic signature of EAT, unlike SAT. Plasma lipoprotein lipidome only partially reflected EAT lipidome.
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Affiliation(s)
- Magali Barchuk
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Departamento de Bioquímica Clínica, Laboratorio de Lípidos y Aterosclerosis, Buenos Aires, Argentina (M.B., V.M., G.L., L.S., G.B.)
| | - Anne Dutour
- Aix-Marseille University, INSERM, INRAE, C2VN, France (A.D., P.A., L.S., R.V., S.B., J.C.M., B.G.).,Endocrinology, Metabolic Diseases and Nutrition Department, Assistance Publique Hôpitaux de Marseille, France (A.D., R.V., S.B., B.G.)
| | - Patricia Ancel
- Aix-Marseille University, INSERM, INRAE, C2VN, France (A.D., P.A., L.S., R.V., S.B., J.C.M., B.G.)
| | - Ljubica Svilar
- Aix-Marseille University, INSERM, INRAE, C2VN, France (A.D., P.A., L.S., R.V., S.B., J.C.M., B.G.).,CRIBIOM, Criblage Biologique Marseille, Faculté de Medecine de la Timone, France (L.S.)
| | - Veronica Miksztowicz
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Departamento de Bioquímica Clínica, Laboratorio de Lípidos y Aterosclerosis, Buenos Aires, Argentina (M.B., V.M., G.L., L.S., G.B.).,Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Argentina (V.M., G.B.)
| | - Graciela Lopez
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Departamento de Bioquímica Clínica, Laboratorio de Lípidos y Aterosclerosis, Buenos Aires, Argentina (M.B., V.M., G.L., L.S., G.B.)
| | - Miguel Rubio
- Universidad de Buenos Aires, Hospital de Clínicas "José de San Martín", División de Cirugía Cardiovascular, Argentina (M.R.)
| | - Laura Schreier
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Departamento de Bioquímica Clínica, Laboratorio de Lípidos y Aterosclerosis, Buenos Aires, Argentina (M.B., V.M., G.L., L.S., G.B.)
| | - Juan Patricio Nogueira
- Servicio de Docencia e Investigación, Hospital Central de Formosa, Facultad de Ciencias de la Salud, Universidad Nacional de Formosa, Argentina (J.P.N.)
| | - René Valéro
- Aix-Marseille University, INSERM, INRAE, C2VN, France (A.D., P.A., L.S., R.V., S.B., J.C.M., B.G.).,Endocrinology, Metabolic Diseases and Nutrition Department, Assistance Publique Hôpitaux de Marseille, France (A.D., R.V., S.B., B.G.)
| | - Sophie Béliard
- Aix-Marseille University, INSERM, INRAE, C2VN, France (A.D., P.A., L.S., R.V., S.B., J.C.M., B.G.).,Endocrinology, Metabolic Diseases and Nutrition Department, Assistance Publique Hôpitaux de Marseille, France (A.D., R.V., S.B., B.G.)
| | - Jean Charles Martin
- Aix-Marseille University, INSERM, INRAE, C2VN, France (A.D., P.A., L.S., R.V., S.B., J.C.M., B.G.)
| | - Gabriela Berg
- From the Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Instituto de Fisiopatología y Bioquímica Clínica (INFIBIOC), Departamento de Bioquímica Clínica, Laboratorio de Lípidos y Aterosclerosis, Buenos Aires, Argentina (M.B., V.M., G.L., L.S., G.B.).,Universidad de Buenos Aires, CONICET, Facultad de Farmacia y Bioquímica, Argentina (V.M., G.B.)
| | - Bénédicte Gaborit
- Aix-Marseille University, INSERM, INRAE, C2VN, France (A.D., P.A., L.S., R.V., S.B., J.C.M., B.G.).,Endocrinology, Metabolic Diseases and Nutrition Department, Assistance Publique Hôpitaux de Marseille, France (A.D., R.V., S.B., B.G.)
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9
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Meex RCR, Blaak EE, van Loon LJC. Lipotoxicity plays a key role in the development of both insulin resistance and muscle atrophy in patients with type 2 diabetes. Obes Rev 2019; 20:1205-1217. [PMID: 31240819 PMCID: PMC6852205 DOI: 10.1111/obr.12862] [Citation(s) in RCA: 95] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 12/12/2022]
Abstract
Insulin resistance and muscle mass loss often coincide in individuals with type 2 diabetes. Most patients with type 2 diabetes are overweight, and it is well established that obesity and derangements in lipid metabolism play an important role in the development of insulin resistance in these individuals. Specifically, increased adipose tissue mass and dysfunctional adipose tissue lead to systemic lipid overflow and to low-grade inflammation via altered secretion of adipokines and cytokines. Furthermore, an increased flux of fatty acids from the adipose tissue may contribute to increased fat storage in the liver and in skeletal muscle, resulting in an altered secretion of hepatokines, mitochondrial dysfunction, and impaired insulin signalling in skeletal muscle. Recent studies suggest that obesity and lipid derangements in adipose tissue can also lead to the development of muscle atrophy, which would make insulin resistance and muscle atrophy two sides of the same coin. Unfortunately, the exact relationship between lipid accumulation, type 2 diabetes, and muscle atrophy remains largely unexplored. The aim of this review is to discuss the relationship between type 2 diabetes and muscle loss and to discuss some of the joint pathways through which lipid accumulation in organs may affect peripheral insulin sensitivity and muscle mass.
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Affiliation(s)
- Ruth C R Meex
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Ellen E Blaak
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Luc J C van Loon
- Department of Human Biology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
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10
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Chen L, Liu Q, Tang Q, Kuang J, Li H, Pu S, Wu T, Yang X, Li R, Zhang J, Zhang Z, Huang Y, Li Y, Zou M, Jiang W, Li T, Gong M, Zhang L, Wang H, Qu A, Xie W, He J. Hepatocyte-specific Sirt6 deficiency impairs ketogenesis. J Biol Chem 2018; 294:1579-1589. [PMID: 30530497 DOI: 10.1074/jbc.ra118.005309] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 11/15/2018] [Indexed: 02/05/2023] Open
Abstract
Sirt6 is an NADH (NAD+)-dependent deacetylase with a critical role in hepatic lipid metabolism. Ketogenesis is controlled by a signaling network of hepatic lipid metabolism. However, how Sirt6 functions in ketogenesis remains unclear. Here, we demonstrated that Sirt6 functions as a mediator of ketogenesis in response to a fasting and ketogenic diet (KD). The KD-fed hepatocyte-specific Sirt6 deficiency (HKO) mice exhibited impaired ketogenesis, which was due to enhanced Fsp27 (fat-specific induction of protein 27), a protein known to regulate lipid metabolism. In contrast, overexpression of Sirt6 in mouse primary hepatocytes promoted ketogenesis. Mechanistically, Sirt6 repressed Fsp27β expression by interacting with Crebh (cAMP response element-binding protein H) and preventing its recruitment to the Fsp27β gene promoter. The KD-fed HKO mice also showed exacerbated hepatic steatosis and inflammation. Finally, Fsp27 silencing rescued hypoketonemia and other metabolic phenotypes in KD-fed HKO mice. Our data suggest that the Sirt6-Crebh-Fsp27 axis is pivotal for hepatic lipid metabolism and inflammation. Sirt6 may be a pharmacological target to remedy metabolic diseases.
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Affiliation(s)
- Lei Chen
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Qinhui Liu
- Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Qin Tang
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Jiangying Kuang
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Hong Li
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Shiyun Pu
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Tong Wu
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Xuping Yang
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Rui Li
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Jinhang Zhang
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Zijing Zhang
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Ya Huang
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Yanping Li
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Min Zou
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Wei Jiang
- Molecular Medicine Research Center, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Tao Li
- West China-Washington Mitochondria and Metabolism Center and Laboratory of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Meng Gong
- West China-Washington Mitochondria and Metabolism Center and Laboratory of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Lu Zhang
- West China-Washington Mitochondria and Metabolism Center and Laboratory of Anesthesiology, West China Hospital, Sichuan University, Chengdu 610041, China
| | - Hua Wang
- Department of Oncology, First Affiliated Hospital of Anhui Medical University, Hefei 230022, China
| | - Aijuan Qu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China 100069
| | - Wen Xie
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260.
| | - Jinhan He
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, China; Laboratory of Clinical Pharmacy and Adverse Drug Reaction, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
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11
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Lund J, Helle SA, Li Y, Løvsletten NG, Stadheim HK, Jensen J, Kase ET, Thoresen GH, Rustan AC. Higher lipid turnover and oxidation in cultured human myotubes from athletic versus sedentary young male subjects. Sci Rep 2018; 8:17549. [PMID: 30510272 PMCID: PMC6277406 DOI: 10.1038/s41598-018-35715-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 11/07/2018] [Indexed: 12/19/2022] Open
Abstract
In this study we compared fatty acid (FA) metabolism in myotubes established from athletic and sedentary young subjects. Six healthy sedentary (maximal oxygen uptake (VO2max) ≤ 46 ml/kg/min) and six healthy athletic (VO2max > 60 ml/kg/min) young men were included. Myoblasts were cultured and differentiated to myotubes from satellite cells isolated from biopsy of musculus vastus lateralis. FA metabolism was studied in myotubes using [14C]oleic acid. Lipid distribution was assessed by thin layer chromatography, and FA accumulation, lipolysis and re-esterification were measured by scintillation proximity assay. Gene and protein expressions were studied. Myotubes from athletic subjects showed lower FA accumulation, lower incorporation of FA into total lipids, triacylglycerol (TAG), diacylglycerol and cholesteryl ester, higher TAG-related lipolysis and re-esterification, and higher complete oxidation and incomplete β-oxidation of FA compared to myotubes from sedentary subjects. mRNA expression of the mitochondrial electron transport chain complex III gene UQCRB was higher in cells from athletic compared to sedentary. Myotubes established from athletic subjects have higher lipid turnover and oxidation compared to myotubes from sedentary subjects. Our findings suggest that cultured myotubes retain some of the phenotypic traits of their donors.
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Affiliation(s)
- Jenny Lund
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway.
| | - Siw A Helle
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Yuchuan Li
- Department of Nutrition, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Nils G Løvsletten
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - Hans K Stadheim
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Eili T Kase
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
| | - G Hege Thoresen
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway.,Department of Pharmacology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Arild C Rustan
- Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo, Norway
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12
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Joseph JS, Ayeleso AO, Mukwevho E. Importance of CaMKII activation in the regulation of adiposomes and ATP concentration in rat skeletal muscle. ACTA ACUST UNITED AC 2018. [DOI: 10.1080/0035919x.2018.1476421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Jitcy S. Joseph
- Department of Biochemistry, University of Johannesburg, Auckland Park 2006, South Africa
| | - Ademola O. Ayeleso
- Department of Biochemistry, North-West University, Mafikeng Campus, Mmabatho, 2735, South Africa
| | - Emmanuel Mukwevho
- Department of Biochemistry, North-West University, Mafikeng Campus, Mmabatho, 2735, South Africa
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13
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Rogne M, Chu DT, Küntziger TM, Mylonakou MN, Collas P, Tasken K. OPA1-anchored PKA phosphorylates perilipin 1 on S522 and S497 in adipocytes differentiated from human adipose stem cells. Mol Biol Cell 2018; 29:1487-1501. [PMID: 29688805 PMCID: PMC6014102 DOI: 10.1091/mbc.e17-09-0538] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Optic atrophy 1 (OPA1) is the A-kinase anchoring protein targeting the pool of protein kinase A (PKA) responsible for perilipin 1 phosphorylation, a gatekeeper for lipolysis. However, the involvement of OPA1-bound PKA in the downstream regulation of lipolysis is unknown. Here we show up-regulation and relocation of OPA1 from mitochondria to lipid droplets during adipocytic differentiation of human adipose stem cells. We employed various biochemical and immunological approaches to demonstrate that OPA1-bound PKA phosphorylates perilipin 1 at S522 and S497 on lipolytic stimulation. We show that the first 30 amino acids of OPA1 are essential for its lipid droplet localization as is OMA1-dependent processing. Finally, our results indicate that presence of OPA1 is necessary for lipolytic phosphorylation of downstream targets. Our results show for the first time, to our knowledge, how OPA1 mediates adrenergic control of lipolysis in human adipocytes by regulating phosphorylation of perilipin 1.
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Affiliation(s)
- Marie Rogne
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | - Dinh-Toi Chu
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | | | - Maria-Niki Mylonakou
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway
| | - Philippe Collas
- Department of Molecular Medicine, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0318 Oslo, Norway.,Norewegian Center for Stem Cell Research, Department of Immunology and Transfusion Medicine, Oslo University Hospital, 0424 Oslo, Norway
| | - Kjetil Tasken
- Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, 0318 Oslo, Norway.,Department of Cancer Immunology, Institute of Cancer Research, Oslo University Hospital, 0424 Oslo, Norway
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14
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Thankamony A, Kemp GJ, Koulman A, Bokii V, Savage DB, Boesch C, Hodson L, Dunger DB, Sleigh A. Compositional marker in vivo reveals intramyocellular lipid turnover during fasting-induced lipolysis. Sci Rep 2018; 8:2750. [PMID: 29426847 PMCID: PMC5807358 DOI: 10.1038/s41598-018-21170-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 01/30/2018] [Indexed: 01/28/2023] Open
Abstract
Intramyocellular lipid (IMCL) is of particular metabolic interest, but despite many proton magnetic resonance spectroscopy (1H MRS) studies reporting IMCL content measured by the methylene (CH2) resonance signal, little is known about its composition. Here we validated IMCL CH3:CH2 ratio as a compositional marker using 1H MRS at short echo time, and investigated IMCL content and composition during a 28-hour fast in 24 healthy males. Increases in IMCL CH2 relative to the creatine and phosphocreatine resonance (Cr) at 3.0 ppm (an internal standard) correlated with circulating free fatty acid (FA) concentrations, supporting the concept of increased FA influx into IMCL. Significant decreases in IMCL CH3:CH2 ratio indicated a less unsaturated IMCL pool after fasting, and this compositional change related inversely to IMCL baseline composition, suggesting a selective efflux of unsaturated shorter-chain FA from the IMCL pool. This novel in vivo evidence reveals IMCL turnover during extended fasting, consistent with the concept of a flexible, responsive myocellular lipid store. There were also differences between soleus and tibialis anterior in basal IMCL composition and in response to fasting. We discuss the potential of this marker for providing insights into normal physiology and mechanisms of disease.
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Affiliation(s)
- Ajay Thankamony
- Department of Paediatrics, University of Cambridge, Cambridge, UK
| | - Graham J Kemp
- Department of Musculoskeletal Biology, University of Liverpool and MRC-Arthritis Research UK Centre for Integrated research into Musculoskeletal Ageing (CIMA), Liverpool, UK
| | - Albert Koulman
- National Institute for Health Research Biomedical Research Centre (NIHR BRC) Core Metabolomics and Lipidomics Laboratory, University of Cambridge, Cambridge, UK.,Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Vlada Bokii
- Wolfson Brain Imaging Centre, University of Cambridge School of Clinical Medicine, Cambridge, UK
| | - David B Savage
- Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Chris Boesch
- Department of Clinical Research and Radiology, AMSM, University Bern, Bern, Switzerland
| | - Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism (OCDEM), Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - David B Dunger
- Department of Paediatrics, University of Cambridge, Cambridge, UK.,Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Alison Sleigh
- Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK. .,Wolfson Brain Imaging Centre, University of Cambridge School of Clinical Medicine, Cambridge, UK. .,National Institute for Health Research/Wellcome Trust Clinical Research Facility, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
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15
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Clark JF, Meade M, Ranepura G, Hall DH, Savage-Dunn C. Caenorhabditis elegans DBL-1/BMP Regulates Lipid Accumulation via Interaction with Insulin Signaling. G3 (BETHESDA, MD.) 2018; 8:343-351. [PMID: 29162682 PMCID: PMC5765361 DOI: 10.1534/g3.117.300416] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 11/18/2017] [Indexed: 11/23/2022]
Abstract
Metabolic homeostasis is coordinately controlled by diverse inputs. Understanding these regulatory networks is vital to combating metabolic disorders. The nematode Caenorhabditis elegans has emerged as a powerful, genetically tractable model system for the discovery of lipid regulatory mechanisms. Here we introduce DBL-1, the C. elegans homolog of bone morphogenetic protein 2/4 (BMP2/4), as a significant regulator of lipid homeostasis. We used neutral lipid staining and a lipid droplet marker to demonstrate that both increases and decreases in DBL-1/BMP signaling result in reduced lipid stores and lipid droplet count. We find that lipid droplet size, however, correlates positively with the level of DBL-1/BMP signaling. Regulation of lipid accumulation in the intestine occurs through non-cell-autonomous signaling, since expression of SMA-3, a Smad signal transducer, in the epidermis (hypodermis) is sufficient to rescue the loss of lipid accumulation. Finally, genetic evidence indicates that DBL-1/BMP functions upstream of Insulin/IGF-1 Signaling in lipid metabolism. We conclude that BMP signaling regulates lipid metabolism in C. elegans through interorgan signaling to the Insulin pathway, shedding light on a less well-studied regulatory mechanism for metabolic homeostasis.
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Affiliation(s)
- James F Clark
- Ph.D. Program in Biology, The Graduate Center, City University of New York (CUNY), New York, New York 10016
- Biology Department, Queens College, CUNY, Flushing, New York 11367
| | - Michael Meade
- Biology Department, Queens College, CUNY, Flushing, New York 11367
| | - Gehan Ranepura
- Biology Department, Queens College, CUNY, Flushing, New York 11367
| | - David H Hall
- Department of Neuroscience, Albert Einstein College of Medicine, New York, New York 10461
| | - Cathy Savage-Dunn
- Ph.D. Program in Biology, The Graduate Center, City University of New York (CUNY), New York, New York 10016
- Biology Department, Queens College, CUNY, Flushing, New York 11367
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16
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Wu W, Xu Z, Zhang L, Liu J, Feng J, Wang X, Shan T, Wang Y. Muscle-specific deletion of Prkaa1 enhances skeletal muscle lipid accumulation in mice fed a high-fat diet. J Physiol Biochem 2017; 74:195-205. [DOI: 10.1007/s13105-017-0604-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 12/20/2017] [Indexed: 12/31/2022]
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17
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Ajith TA, Jayakumar TG. Peroxisome proliferator-activated receptors in cardiac energy metabolism and cardiovascular disease. Clin Exp Pharmacol Physiol 2017; 43:649-58. [PMID: 27115677 DOI: 10.1111/1440-1681.12579] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/28/2016] [Accepted: 04/08/2016] [Indexed: 11/30/2022]
Abstract
Cardiomyocytes mainly depend on energy produced from the oxidation of fatty acids and mitochondrial oxidative phosphorylation. Shortage of energy or excessive fat accumulation can lead to cardiac disorders. High saturated fat intake and a sedentary life style have a major influence in the development of cardiovascular disease (CVD). Peroxisome proliferator-activated receptors (PPARs), one of the nuclear receptor super family members, play critical role in the metabolism of lipids by regulating their oxidation and storage. Furthermore, they are involved in glucose homeostasis as well. PPARs, mainly alpha (α) and beta/delta (β/δ), have a significant effect on the lipid metabolism and anti-inflammation in endothelial cells (ECs), vascular smooth muscle cells, and also in cardiomyocytes. Pro-inflammatory cytokines, mainly tumour necrosis factor-α, released at the site of inflammation in the sub-ECs of coronary arteries can inactivate the PPARs which can eventually lead to decreased energy production in the myocardium. Various synthetic ligands of PPAR-α and β/δ have many favourable effects in modulating the vascular diseases and heart failure. Despite the adverse effects from therapy using PPAR- gamma ligands, several laboratories are now focused on synthesizing partial activators which may combine their beneficial effects with lowering of undesirable side effects. This review discusses the role of isoforms of PPAR in the cardiomyocytes energy balance and CVD. The knowledge will help in the synthesis of ligands for their partial activation in order to render energy balance and protection from CVD.
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18
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Komiya Y, Sawano S, Mashima D, Ichitsubo R, Nakamura M, Tatsumi R, Ikeuchi Y, Mizunoya W. Mouse soleus (slow) muscle shows greater intramyocellular lipid droplet accumulation than EDL (fast) muscle: fiber type-specific analysis. J Muscle Res Cell Motil 2017; 38:163-173. [PMID: 28281032 DOI: 10.1007/s10974-017-9468-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/16/2017] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is the main tissue of lipid metabolism and accordingly is critical for homeostasis and energy production; however, the determinants of lipid accumulation in skeletal muscle are unknown. Here, we examined whether the soleus muscle (predominantly slow-twitch fibers) has a higher lipid accumulation capacity than that of the extensor digitorum longus (EDL, predominantly fast-twitch fibers) muscle in mice. Soleus and EDL muscles were harvested from male C57BL/6J mice. The mRNA levels of genes involved in fatty acid import and triglyceride synthesis and accumulation were examined in soleus and EDL muscles. The intramyocellular lipid (IMCL) droplets of muscle cross sections and isolated single fibers were visualized by staining with BODIPY493/503, and fiber types were determined by immunofluorescent detection of myosin heavy chain (MyHC) isoforms. We detected higher mRNA expression of genes related to lipid accumulation in the soleus than the EDL. We also observed a marked increase of IMCL in single fibers from the soleus, but not the EDL, after treatment with a high-fat diet plus denervation. Interestingly, greater accumulation of IMCL droplets was observed in type 2A and 2X fibers (MyHC2A- and MyHC2X-positive fibers) than type 1 fibers (MyHC1-positive fibers) in soleus muscles. These results suggest that the soleus contains more IMCL owing to the higher population of type 2A fibers, and the difference in lipid accumulation between the soleus and EDL could depend on fiber type composition.
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Affiliation(s)
- Yusuke Komiya
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
- Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, 034-8628, Japan
| | - Shoko Sawano
- Department of Food Nutrition, Fukuoka Women's Junior College, Dazaifu, 818-0193, Japan
| | - Daisuke Mashima
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Riho Ichitsubo
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Mako Nakamura
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Ryuichi Tatsumi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Yoshihide Ikeuchi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Wataru Mizunoya
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
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19
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Wu W, Feng J, Jiang D, Zhou X, Jiang Q, Cai M, Wang X, Shan T, Wang Y. AMPK regulates lipid accumulation in skeletal muscle cells through FTO-dependent demethylation of N 6-methyladenosine. Sci Rep 2017; 7:41606. [PMID: 28176824 PMCID: PMC5296945 DOI: 10.1038/srep41606] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 12/22/2016] [Indexed: 11/28/2022] Open
Abstract
Skeletal muscle plays important roles in whole-body energy homeostasis. Excessive skeletal muscle lipid accumulation is associated with some metabolic diseases such as obesity and Type 2 Diabetes. The energy sensor AMPK (AMP-activated protein kinase) is a key regulator of skeletal muscle lipid metabolism, but the precise regulatory mechanism remains to be elucidated. Here, we provide a novel mechanism by which AMPK regulates skeletal muscle lipid accumulation through fat mass and obesity-associated protein (FTO)-dependent demethylation of N6-methyladenosine (m6A). We confirmed an inverse correlation between AMPK and skeletal muscle lipid content. Moreover, inhibition of AMPK enhanced lipid accumulation, while activation of AMPK reduced lipid accumulation in skeletal muscle cells. Notably, we found that mRNA m6A methylation levels were inversely correlated with lipid content in skeletal muscle. Furthermore, AMPK positively regulated the m6A methylation levels of mRNA, which could negatively regulate lipid accumulation in C2C12. At the molecular level, we demonstrated that AMPK regulated lipid accumulation in skeletal muscle cells by regulating FTO expression and FTO-dependent demethylation of m6A. Together, these results provide a novel regulatory mechanism of AMPK on lipid metabolism in skeletal muscle cells and suggest the possibility of controlling skeletal muscle lipid deposition by targeting AMPK or using m6A related drugs.
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Affiliation(s)
- Weiche Wu
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Jie Feng
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Denghu Jiang
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Xihong Zhou
- Institute of Subtropical Agriculture, The Chinese Academy of Science, Changsha, Hunan 410125, P. R. China
| | - Qin Jiang
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Min Cai
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Xinxia Wang
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Tizhong Shan
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
| | - Yizhen Wang
- College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition & Feed Sciences, Ministry of Agriculture; Zhejiang Provincial Laboratory of Feed and Animal Nutrition, No. 866 Yuhangtang Road, Hangzhou, Zhejiang, 310058, P. R. China
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The Flexibility of Ectopic Lipids. Int J Mol Sci 2016; 17:ijms17091554. [PMID: 27649157 PMCID: PMC5037826 DOI: 10.3390/ijms17091554] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 02/07/2023] Open
Abstract
In addition to the subcutaneous and the visceral fat tissue, lipids can also be stored in non-adipose tissue such as in hepatocytes (intrahepatocellular lipids; IHCL), skeletal (intramyocellular lipids; IMCL) or cardiac muscle cells (intracardiomyocellular lipids; ICCL). Ectopic lipids are flexible fuel stores that can be depleted by physical exercise and repleted by diet. They are related to obesity and insulin resistance. Quantification of IMCL was initially performed invasively, using muscle biopsies with biochemical and/or histological analysis. 1H-magnetic resonance spectroscopy (1H-MRS) is now a validated method that allows for not only quantifying IMCL non-invasively and repeatedly, but also assessing IHCL and ICCL. This review summarizes the current available knowledge on the flexibility of ectopic lipids. The available evidence suggests a complex interplay between quantitative and qualitative diet, fat availability (fat mass), insulin action, and physical exercise, all important factors that influence the flexibility of ectopic lipids. Furthermore, the time frame of the intervention on these parameters (short-term vs. long-term) appears to be critical. Consequently, standardization of physical activity and diet are critical when assessing ectopic lipids in predefined clinical situations.
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Affourtit C. Mitochondrial involvement in skeletal muscle insulin resistance: A case of imbalanced bioenergetics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2016; 1857:1678-93. [PMID: 27473535 DOI: 10.1016/j.bbabio.2016.07.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/19/2016] [Accepted: 07/23/2016] [Indexed: 12/16/2022]
Abstract
Skeletal muscle insulin resistance in obesity associates with mitochondrial dysfunction, but the causality of this association is controversial. This review evaluates mitochondrial models of nutrient-induced muscle insulin resistance. It transpires that all models predict that insulin resistance arises as a result of imbalanced cellular bioenergetics. The nature and precise origin of the proposed insulin-numbing molecules differ between models but all species only accumulate when metabolic fuel supply outweighs energy demand. This observation suggests that mitochondrial deficiency in muscle insulin resistance is not merely owing to intrinsic functional defects, but could instead be an adaptation to nutrient-induced changes in energy expenditure. Such adaptive effects are likely because muscle ATP supply is fully driven by energy demand. This market-economic control of myocellular bioenergetics offers a mechanism by which insulin-signalling deficiency can cause apparent mitochondrial dysfunction, as insulin resistance lowers skeletal muscle anabolism and thus dampens ATP demand and, consequently, oxidative ATP synthesis.
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Affiliation(s)
- Charles Affourtit
- School of Biomedical and Healthcare Sciences, Plymouth University Peninsula Schools of Medicine and Dentistry, Plymouth University, Drake Circus, PL4 8AA Plymouth, UK.
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22
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Kim TN. Diverse Abnormal Body Composition Phenotypes: Interaction Between Muscle, Fat, and Bone. ACTA ACUST UNITED AC 2015. [DOI: 10.7570/kjo.2015.24.1.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Tae Nyun Kim
- Department of Internal Medicine, Cardiovascular and Metabolic Disease Center, Inje University, Busan, Korea
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23
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Kang SI, Shin HS, Kim SJ. Sinensetin enhances adipogenesis and lipolysis by increasing cyclic adenosine monophosphate levels in 3T3-L1 adipocytes. Biol Pharm Bull 2015; 38:552-8. [PMID: 25735898 DOI: 10.1248/bpb.b14-00700] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sinensetin is a rare polymethoxylated flavone (PMF) found in certain citrus fruits. In this study, we investigated the effects of sinensetin on lipid metabolism in 3T3-L1 cells. Sinensetin promoted adipogenesis in 3T3-L1 preadipocytes growing in incomplete differentiation medium, which did not contain 3-isobutyl-1-methylxanthine. Sinensetin up-regulated expression of the adipogenic transcription factors peroxisome proliferator-activated receptor γ, CCAAT/enhancer-binding protein (C/EBP) α, and sterol regulatory element-binding protein 1c. It also potentiated expression of C/EBPβ and activation of cAMP-responsive element-binding protein. Sinensetin enhanced activation of protein kinase A and increased intracellular cAMP levels in 3T3-L1 preadipocytes. In mature 3T3-L1 adipocytes, sinensetin stimulated lipolysis via a cAMP pathway. Taken together, these results suggest that sinensetin enhances adipogenesis and lipolysis by increasing cAMP levels in adipocytes.
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24
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Rohwedder A, Zhang Q, Rudge SA, Wakelam MJO. Lipid droplet formation in response to oleic acid in Huh-7 cells is mediated by the fatty acid receptor FFAR4. J Cell Sci 2014; 127:3104-15. [PMID: 24876224 DOI: 10.1242/jcs.145854] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
It is unclear how changes in lipid droplet size and number are regulated - for example, it is not known whether this involves a signalling pathway or is directed by cellular lipid uptake. Here, we show that oleic acid stimulates lipid droplet formation by activating the long-chain fatty acid receptor FFAR4, which signals through a pertussis-toxin-sensitive G-protein signalling pathway involving phosphoinositide 3-kinase (PI3-kinase), AKT (also known as protein kinase B) and phospholipase D (PLD) activities. This initial lipid droplet formation is not dependent upon exogenous lipid, whereas the subsequent more sustained increase in the number of lipid droplets is dependent upon lipid uptake. These two mechanisms of lipid droplet formation point to distinct potential intervention points.
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Affiliation(s)
- Arndt Rohwedder
- Signalling Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Qifeng Zhang
- Signalling Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Simon A Rudge
- Signalling Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Michael J O Wakelam
- Signalling Programme, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
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25
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Cao P, Fan SJ, Wang AM, Xie VB, Qiao Z, Brittenham GM, Wu EX. Diffusion magnetic resonance monitors intramyocellular lipid droplet size in vivo. Magn Reson Med 2014; 73:59-69. [PMID: 24469956 DOI: 10.1002/mrm.25116] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 11/23/2013] [Accepted: 12/13/2013] [Indexed: 01/09/2023]
Abstract
PURPOSE Intramyocellular lipid (IMCL) droplets are dynamic organelles whose morphology reflects their vital roles in lipid synthesis, usage, and storage in muscle energy metabolism. To develop noninvasive means to measure droplet microstructure in vivo, we investigated the molecular diffusion behavior of IMCL with diffusion magnetic resonance spectroscopy. METHODS Using extremely large diffusion weighting, we measured the IMCL apparent diffusion coefficients (ADCs) in hindlimb muscle of rodents from normal feeding, 60-h fasting, streptozotocin-induced diabetic, and high-fat-diet-induced obese groups. RESULTS IMCL ADCs decreased markedly with diffusion time, confirming the restricted diffusion of lipid molecules within IMCL droplets. IMCL droplet size, determined by transmission electron microscopy, was closely correlated with ADC. IMCL ADC was sensitive to metabolic alterations, decreasing in the 60-h fasting and diabetic groups while increasing in the obese group. These findings indicated that the IMCL droplet size decreased following 60-h fasting and in STZ-induced diabetes but increased in high-fat-diet-induced obesity. CONCLUSION MR diffusion characterization of IMCL droplet size provides a unique means to examine the intracellular lipid dynamics and metabolic abnormalities in vivo.
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Affiliation(s)
- Peng Cao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Shu-Juan Fan
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Anna M Wang
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Victor B Xie
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Zhongwei Qiao
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Gary M Brittenham
- Departments of Pediatrics and Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Ed X Wu
- Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.,Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China
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26
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Komolka K, Albrecht E, Wimmers K, Michal JJ, Maak S. Molecular heterogeneities of adipose depots - potential effects on adipose-muscle cross-talk in humans, mice and farm animals. J Genomics 2014; 2:31-44. [PMID: 25057322 PMCID: PMC4105427 DOI: 10.7150/jgen.5260] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Adipose tissue is considered as a major endocrine organ that secretes numerous proteins called adipokines. The heterogeneous nature of adipose tissue in different parts of the body suggests respective heterogeneity of proteomes and secretomes. This review consolidates knowledge from recent studies targeting the diversity of different adipose depots affecting the pattern of secreted adipokines and discusses potential consequences for the cross-talk between adipose and skeletal muscle in humans, rodent models and farm animals. Special attention is paid to muscle-associated fat depots like inter- and intramuscular fat that become focus of attention in the context of the rather new notion of skeletal muscle as a major endocrine organ. Understanding the complexity of communication between adipocytes and skeletal muscle cells will allow developing strategies for improvement of human health and for sustainable production of high quality meat.
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Affiliation(s)
- Katrin Komolka
- 1. Research Unit Muscle Biology and Growth, Leibniz-Institute for Farm Animal Biology (FBN), W.-Stahl-Allee 2, D-18196 Dummerstorf, Germany
| | - Elke Albrecht
- 1. Research Unit Muscle Biology and Growth, Leibniz-Institute for Farm Animal Biology (FBN), W.-Stahl-Allee 2, D-18196 Dummerstorf, Germany
| | - Klaus Wimmers
- 2. Research Unit Molecular Biology, Leibniz-Institute for Farm Animal Biology (FBN), W.-Stahl-Allee 2, D-18196 Dummerstorf, Germany
| | - Jennifer J Michal
- 3. Department of Animal Sciences, Washington State University, Pullman, WA 99164, USA
| | - Steffen Maak
- 1. Research Unit Muscle Biology and Growth, Leibniz-Institute for Farm Animal Biology (FBN), W.-Stahl-Allee 2, D-18196 Dummerstorf, Germany
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27
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Jové M, Moreno-Navarrete JM, Pamplona R, Ricart W, Portero-Otín M, Fernández-Real JM. Human omental and subcutaneous adipose tissue exhibit specific lipidomic signatures. FASEB J 2013; 28:1071-81. [PMID: 24265485 DOI: 10.1096/fj.13-234419] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Despite their differential effects on human metabolic pathophysiology, the differences in omental and subcutaneous lipidomes are largely unknown. To explore this field, liquid chromatography coupled with mass spectrometry was used for lipidome analyses of adipose tissue samples (visceral and subcutaneous) selected from a group of obese subjects (n=38). Transcriptomics and in vitro studies in adipocytes were used to confirm the pathways affected by location. The analyses revealed the existence of obesity-related specific lipidome signatures in each of these locations, attributed to selective enrichment of specific triglycerides, glycerophospholipids, and sphingolipids, because these were not observed in adipose tissues from nonobese individuals. The changes were compatible with subcutaneous enrichment in pathways involved in adipogenesis, triacylglyceride synthesis, and lipid droplet formation, as well as increased α-oxidation. Marked differences between omental and subcutaneous depots in obese individuals were seen in the association of lipid species with metabolic traits (body mass index and insulin sensitivity). Targeted studies also revealed increased cholesterol (Δ56%) and cholesterol epoxide (Δ34%) concentrations in omental adipose tissue. In view of the effects of cholesterol epoxide, which induced enhanced expression of adipocyte differentiation and α-oxidation genes in human omental adipocytes, a novel role for cholesterol epoxide as a signaling molecule for differentiation is proposed. In summary, in obesity, adipose tissue exhibits a location-specific differential lipid profile that may contribute to explaining part of its distinct pathogenic role.
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Affiliation(s)
- Mariona Jové
- 1Section of Diabetes, Endocrinology and Nutrition, Hospital of Girona "Dr Josep Trueta," Carretera de França s/n, 17007, Girona, Spain.
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28
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Chen Y, Ding Y, Yang L, Yu J, Liu G, Wang X, Zhang S, Yu D, Song L, Zhang H, Zhang C, Huo L, Huo C, Wang Y, Du Y, Zhang H, Zhang P, Na H, Xu S, Zhu Y, Xie Z, He T, Zhang Y, Wang G, Fan Z, Yang F, Liu H, Wang X, Zhang X, Zhang MQ, Li Y, Steinbüchel A, Fujimoto T, Cichello S, Yu J, Liu P. Integrated omics study delineates the dynamics of lipid droplets in Rhodococcus opacus PD630. Nucleic Acids Res 2013; 42:1052-64. [PMID: 24150943 PMCID: PMC3902926 DOI: 10.1093/nar/gkt932] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Rhodococcus opacus strain PD630 (R. opacus PD630), is an oleaginous bacterium, and also is one of few prokaryotic organisms that contain lipid droplets (LDs). LD is an important organelle for lipid storage but also intercellular communication regarding energy metabolism, and yet is a poorly understood cellular organelle. To understand the dynamics of LD using a simple model organism, we conducted a series of comprehensive omics studies of R. opacus PD630 including complete genome, transcriptome and proteome analysis. The genome of R. opacus PD630 encodes 8947 genes that are significantly enriched in the lipid transport, synthesis and metabolic, indicating a super ability of carbon source biosynthesis and catabolism. The comparative transcriptome analysis from three culture conditions revealed the landscape of gene-altered expressions responsible for lipid accumulation. The LD proteomes further identified the proteins that mediate lipid synthesis, storage and other biological functions. Integrating these three omics uncovered 177 proteins that may be involved in lipid metabolism and LD dynamics. A LD structure-like protein LPD06283 was further verified to affect the LD morphology. Our omics studies provide not only a first integrated omics study of prokaryotic LD organelle, but also a systematic platform for facilitating further prokaryotic LD research and biofuel development.
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Affiliation(s)
- Yong Chen
- National Laboratory of Macromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China, MOE Key Laboratory of Bioinformatics and Bioinformatics Division, Center for Synthetic and Systems Biology, TNLIST/Department of Automation, Tsinghua University, Beijing 100084, China, University of the Chinese Academy of Sciences, Beijing 100049, China, Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China, Department of Histology and Embryology, University of South China, Hengyang Hunan Province 421001, China, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China, School of Applied Mathematics, Central University of Finance and Economics, Beijing 102206, China, Department of Molecular and Cell Biology, Center for Systems Biology, The University of Texas at Dallas, Dallas, TX 75083-0688, USA, Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, Corrensstrasse 3, D-48149 Münster, Germany, Environmental Sciences Department, King Abdulaziz University, Jeddah 21589, Saudi Arabia, Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa, Nagoya 466-8550, Japan and School of Life Sciences, La Trobe University, Melbourne, Victoria, 3086, Australia
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Mitochondrial dysfunction induces formation of lipid droplets as a generalized response to stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2013; 2013:327167. [PMID: 24175011 PMCID: PMC3794647 DOI: 10.1155/2013/327167] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 08/20/2013] [Indexed: 01/05/2023]
Abstract
Lipid droplet (LD) formation is a hallmark of cellular stress. Cells attempt to combat noxious stimuli by switching their metabolism from oxidative phosphorylation to glycolysis, sparing resources in LDs for generating cellular reducing power and for anabolic biosynthesis. Membrane phospholipids are also a source of LDs. To elucidate the formation of LDs, we exposed mice to hyperoxia, hypoxia, myocardial ischemia, and sepsis induced by cecal ligation and puncture (CLP). All the above-mentioned stressors enhanced the formation of LDs, as assessed by transmission electron microscopy, with severe mitochondrial swelling. Disruption of mitochondria by depleting mitochondrial DNA ( ρ 0 cells) significantly augmented the formation of LDs, causing transcriptional activation of fatty acid biosynthesis and metabolic reprogramming to glycolysis. Heme oxygenase (HO)-1 counteracts CLP-mediated septic shock in mouse models. In HO-1-deficient mice, LD formation was not observed upon CLP, but a concomitant decrease in "LD-decorating proteins" was observed, implying a link between LDs and cytoprotective activity. Collectively, LD biogenesis during stress can trigger adaptive LD formation, which is dependent on mitochondrial integrity and HO-1 activity; this may be a cellular survival strategy, apportioning energy-generating substrates to cellular defense.
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MacPherson REK, Ramos SV, Vandenboom R, Roy BD, Peters SJ. Skeletal muscle PLIN proteins, ATGL and CGI-58, interactions at rest and following stimulated contraction. Am J Physiol Regul Integr Comp Physiol 2013; 304:R644-50. [PMID: 23408028 DOI: 10.1152/ajpregu.00418.2012] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Evidence indicates that skeletal muscle lipid droplet-associated proteins (PLINs) regulate lipolysis through protein-protein interactions on the lipid droplet surface. In adipocytes, PLIN1 is thought to regulate lipolysis by directly interacting with comparative gene identification-58 (CGI-58), an activator of adipose triglyceride lipase (ATGL). Upon lipolytic stimulation, PLIN1 is phosphorylated, releasing CGI-58 to fully activate ATGL and initiate triglyceride breakdown. The absence of PLIN1 in skeletal muscle leads us to believe that other PLIN family members undertake this role. Our purpose was to examine interactions between PLIN2, PLIN3, and PLIN5, with ATGL and its coactivator CGI-58 at rest and following contraction. Isolated rat solei were incubated for 30 min at rest or during 30 min of intermittent tetanic stimulation [150-ms volleys at 60 Hz with a train rate of 20 tetani/min (25°C)] to maximally stimulate intramuscular lipid breakdown. Results show that the interaction between ATGL and CGI-58 increased 128% following contraction (P = 0.041). Further, ATGL interacts with PLIN2, PLIN3, and PLIN5 at rest and following contraction. The PLIN2-ATGL interaction decreased significantly by 21% following stimulation (P = 0.013). Both PLIN3 and PLIN5 coprecipitated with CGI-58 at rest and following contraction, while there was no detectable interaction between PLIN2 and CGI-58 in either condition. Therefore, our findings indicate that in skeletal muscle, during contraction-induced muscle lipolysis, ATGL and CGI-58 strongly associate and that the PLIN proteins work together to regulate lipolysis, in part, by preventing ATGL and CGI-58 interactions at rest.
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Affiliation(s)
- Rebecca E K MacPherson
- Brock University, Department of Kinesiology, Centre for Bone and Muscle Health, St. Catharines, Canada.
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31
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High-fat load: mechanism(s) of insulin resistance in skeletal muscle. INTERNATIONAL JOURNAL OF OBESITY SUPPLEMENTS 2012; 2:S31-S36. [PMID: 26052434 DOI: 10.1038/ijosup.2012.20] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Skeletal muscle from sedentary obese patients is characterized by depressed electron transport activity, reduced expression of genes required for oxidative metabolism, altered mitochondrial morphology and lower overall mitochondrial content. These findings imply that obesity, or more likely the metabolic imbalance that causes obesity, leads to a progressive decline in mitochondrial function, eventually culminating in mitochondrial dissolution or mitoptosis. A decrease in the sensitivity of skeletal muscle to insulin represents one of the earliest maladies associated with high dietary fat intake and weight gain. Considerable evidence has accumulated to suggest that the cytosolic ectopic accumulation of fatty acid metabolites, including diacylglycerol and ceramides, underlies the development of insulin resistance in skeletal muscle. However, an alternative mechanism has recently been evolving, which places the etiology of insulin resistance in the context of cellular/mitochondrial bioenergetics and redox systems biology. Overnutrition, particularly from high-fat diets, generates fuel overload within the mitochondria, resulting in the accumulation of partially oxidized acylcarnitines, increased mitochondrial hydrogen peroxide (H2O2) emission and a shift to a more oxidized intracellular redox environment. Blocking H2O2 emission prevents the shift in redox environment and preserves insulin sensitivity, providing evidence that the mitochondrial respiratory system is able to sense and respond to cellular metabolic imbalance. Mitochondrial H2O2 emission is a major regulator of protein redox state, as well as the overall cellular redox environment, raising the intriguing possibility that elevated H2O2 emission from nutrient overload may represent the underlying basis for the development of insulin resistance due to disruption of normal redox control mechanisms regulating protein function, including the insulin signaling and glucose transport processes.
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32
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Nevalainen M, Kaakinen M, Rahkila P, Metsikkö K. Reversible stress-induced lipid body formation in fast twitch rat myofibers. Exp Cell Res 2012; 318:2191-9. [PMID: 22771721 DOI: 10.1016/j.yexcr.2012.06.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 06/21/2012] [Accepted: 06/23/2012] [Indexed: 11/16/2022]
Abstract
We analyzed the existence of lipid bodies (LBs) in the fast twitch rat flexor digitorum brevis (FDB) myofibers and found that these structures were scarce. However, isolation procedure of the myofibers, heath shock, viral infection or the glycosylation inhibitor tunicamycin induced formation of the LBs, which were stationary structures flanking Z lines. We next infected FDB myofibers with recombinant Semliki Forest virus expressing caveolin 3-yellow fluorescent protein (cav3-YFP) since this chimeric protein was targeted to the LBs facilitating their further analysis. Photobleaching experiments showed that the LBs recovered cav 3-YFP extremely slowly, indicating that they were not continuous with the endoplasmic/sarcoplasmic reticulum. We found, however, that cav3-YFP could move from the LBs to the sarcolemma and this phenomenon was sensitive to Brefeldin A, suggesting that the chimeric protein could be returned from the LBs to the endoplasmic reticulum.
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Affiliation(s)
- Mika Nevalainen
- Department of Anatomy and Cell Biology, Institute of Biomedicine, P.O. Box 5000, Aapistie 7, FI 90014 University of Oulu, Finland
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Peters SJ, Samjoo IA, Devries MC, Stevic I, Robertshaw HA, Tarnopolsky MA. Perilipin family (PLIN) proteins in human skeletal muscle: the effect of sex, obesity, and endurance training. Appl Physiol Nutr Metab 2012; 37:724-35. [DOI: 10.1139/h2012-059] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Proteins that coat the lipid droplets (also known as PAT proteins or perilipin (PLIN) family proteins) have diverse functions that are not well elucidated in many tissues. In skeletal muscle, there is even less known about the functions or characteristics of these proteins or how they might change in response to perturbations that alter both intramyocellular lipid (IMCL) content and fat utilization and oxidation. Therefore, the purpose of this study was to examine the human muscle content and gene expression of the four skeletal muscle PLIN proteins in both lean and obese men and women and how this was changed following a 12-week endurance training protocol. PLIN2–PLIN5 proteins were all more abundant in women than in men (p = 0.037 and p < 0.0001, respectively), consistent with higher IMCL content observed in female skeletal muscle. PLIN5 (previously known as OXPAT) is of particular interest because it has previously been associated primarily with oxidative tissues that rely heavily on fat oxidation for energy production. Although PLIN5 was not different between lean and obese subjects, it was the only PLIN protein to increase in response to endurance training in both sexes. PLIN5 correlated with IMCL volume (p < 0.0001), but in general, the other PLIN proteins did not correlate well with IMCL volume, suggesting that the relationship between lipid accumulation and PLIN family protein content is not a simple one. Although more work is necessary, it is clear that PLIN5 likely plays an important role in IMCL accumulation and oxidation, both of which increase with endurance training in human skeletal muscle.
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Affiliation(s)
- Sandra J. Peters
- Department of Kinesiology, Faculty of Applied Health Sciences, Centre for Muscle and Bone Health, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Imtiaz A. Samjoo
- Departments of Pediatrics and Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | - Michaela C. Devries
- Departments of Pediatrics and Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | - Ivan Stevic
- Departments of Pediatrics and Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | - Holly A. Robertshaw
- Departments of Pediatrics and Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada
| | - Mark A. Tarnopolsky
- Departments of Pediatrics and Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada
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Abstract
Lipid homeostasis is maintained through the coordination of lipid metabolism in various tissues, including adipose tissue and the liver. The disruption of lipid homeostasis often results in the development of metabolic disorders such as obesity, diabetes mellitus, liver steatosis, and cardiovascular diseases. Cell death-inducing DNA fragmentation factor 45-like effector family proteins, including Cidea, Cideb, and Fsp27 (Cidec), are emerging as important regulators of various lipid metabolic pathways and play pivotal roles in the development of metabolic disorders. This review summarizes the latest cell death-inducing DNA fragmentation factor 45-like effector protein discoveries related to the control of lipid metabolism, with emphasis on the role of these proteins in lipid droplet growth in adipocytes and in the regulation of very low-density lipoprotein lipidation and maturation in hepatocytes.
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Affiliation(s)
- Li Xu
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
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Murphy DJ. The dynamic roles of intracellular lipid droplets: from archaea to mammals. PROTOPLASMA 2012; 249:541-85. [PMID: 22002710 DOI: 10.1007/s00709-011-0329-7] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Accepted: 09/28/2011] [Indexed: 05/02/2023]
Abstract
During the past decade, there has been a paradigm shift in our understanding of the roles of intracellular lipid droplets (LDs). New genetic, biochemical and imaging technologies have underpinned these advances, which are revealing much new information about these dynamic organelles. This review takes a comparative approach by examining recent work on LDs across the whole range of biological organisms from archaea and bacteria, through yeast and Drosophila to mammals, including humans. LDs probably evolved originally in microorganisms as temporary stores of excess dietary lipid that was surplus to the immediate requirements of membrane formation/turnover. LDs then acquired roles as long-term carbon stores that enabled organisms to survive episodic lack of nutrients. In multicellular organisms, LDs went on to acquire numerous additional roles including cell- and organism-level lipid homeostasis, protein sequestration, membrane trafficking and signalling. Many pathogens of plants and animals subvert their host LD metabolism as part of their infection process. Finally, malfunctions in LDs and associated proteins are implicated in several degenerative diseases of modern humans, among the most serious of which is the increasingly prevalent constellation of pathologies, such as obesity and insulin resistance, which is associated with metabolic syndrome.
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Affiliation(s)
- Denis J Murphy
- Division of Biological Sciences, University of Glamorgan, Cardiff, CF37 4AT, UK.
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36
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Abstract
The heart has both the greatest caloric needs and the most robust oxidation of fatty acids (FAs). Under pathological conditions such as obesity and type 2 diabetes, cardiac uptake and oxidation are not balanced and hearts accumulate lipid potentially leading to cardiac lipotoxicity. We will first review the pathways utilized by the heart to acquire FAs from the circulation and to store triglyceride intracellularly. Then we will describe mouse models in which excess lipid accumulation causes heart dysfunction and experiments performed to alleviate this toxicity. Finally, the known relationships between heart lipid metabolism and dysfunction in humans will be summarized.
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Affiliation(s)
- Ira J Goldberg
- Department of Medicine, Columbia University, New York, NY 10032, USA.
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37
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Li X, Ye J, Zhou L, Gu W, Fisher EA, Li P. Opposing roles of cell death-inducing DFF45-like effector B and perilipin 2 in controlling hepatic VLDL lipidation. J Lipid Res 2012; 53:1877-89. [PMID: 22661308 DOI: 10.1194/jlr.m026591] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Regulation of hepatic very low density lipoprotein (VLDL) assembly and maturation is crucial in controlling lipid homeostasis and in the development of metabolic disorders, including obesity, hepatic steatosis, and insulin resistance. Cideb, a member of cell death-inducing DFF45-like effector (CIDE) protein family, has been previously shown to promote VLDL lipidation and maturation. However, the precise subcellular location of Cideb-mediated VLDL lipidation and the factors modulating its activity remain elusive. In addition to its localization to endoplasmic reticulum (ER) and lipid droplets (LD), we observed that Cideb was also localized to the Golgi apparatus. Mature and lipid-rich VLDL particles did not accumulate in the Golgi apparatus in Cideb(-/-) livers. Interestingly, we observed that hepatic perilipin 2/adipose differentiation-related protein (ADRP) levels were markedly increased in Cideb(-/-) mice. Liver-specific knockdown of perilipin 2 in Cideb(-/-) mice resulted in the reduced accumulation of hepatic triglycerides (TAG), increased VLDL-TAG secretion, and the accumulation of mature TAG-rich VLDL in the Golgi apparatus. These data reveal that Cideb and perilipin 2 play opposing roles in controlling VLDL lipidation and hepatic lipid homeostasis.
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Affiliation(s)
- Xuanhe Li
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
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38
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MacPherson REK, Herbst EAF, Reynolds EJ, Vandenboom R, Roy BD, Peters SJ. Subcellular localization of skeletal muscle lipid droplets and PLIN family proteins OXPAT and ADRP at rest and following contraction in rat soleus muscle. Am J Physiol Regul Integr Comp Physiol 2011; 302:R29-36. [PMID: 22012700 DOI: 10.1152/ajpregu.00163.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Skeletal muscle lipid droplet-associated proteins (PLINs) are thought to regulate lipolysis through protein-protein interactions on the lipid droplet surface. In adipocytes, PLIN2 [adipocyte differentiation-related protein (ADRP)] is found only on lipid droplets, while PLIN5 (OXPAT, expressed only in oxidative tissues) is found both on and off the lipid droplet and may be recruited to lipid droplet membranes when needed. Our purpose was to determine whether PLIN5 is recruited to lipid droplets with contraction and to investigate the myocellular location and colocalization of lipid droplets, PLIN2, and PLIN5. Rat solei were isolated, and following a 30-min equilibration period, they were assigned to one of two groups: 1) 30 min of resting incubation and 2) 30 min of stimulation (n = 10 each). Immunofluorescence microscopy was used to determine subcellular content, distribution, and colocalization of lipid droplets, PLIN2, and PLIN5. There was a main effect for lower lipid and PLIN2 content in stimulated compared with rested muscles (P < 0.05). Lipid droplet distribution declined exponentially from the sarcolemma to the fiber center in the rested muscles (P = 0.001, r(2) = 0.99) and linearly in stimulated muscles (slope = -0.0023 ± 0.0006, P < 0.001, r(2) = 0.93). PLIN2 distribution declined exponentially from the sarcolemma to the fiber center in both rested and stimulated muscles (P < 0.0001, r(2) = 0.99 rest; P = 0.0004, r(2) = 0.98 stimulated), while PLIN5 distribution declined linearly (slope = -0.0085 ± 0.0009, P < 0.0001, r(2) = 0.94 rest; slope=-0.0078 ± 0.0010, P = 0.0003, r(2) = 0.91 stimulated). PLIN5-lipid droplets colocalized at rest with no difference poststimulation (P = 0.47; rest r(2) = 0.55 ± 0.02, stimulated r(2) = 0.58 ± 0.03). PLIN2-lipid droplets colocalized at rest with no difference poststimulation (P = 0.48; rest r(2) = 0.66 ± 0.02, stimulated r(2) = 0.65 ± 0.02). Contrary to our hypothesis, these results show that PLIN5 is not recruited to lipid droplets with contraction in isolated skeletal muscle.
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Affiliation(s)
- Rebecca E K MacPherson
- Brock University, Department of Kinesiology, Centre for Muscle Metabolism and Biophysics, Faculty of Applied Health Sciences, St. Catharines, Ontario, Canada.
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Balogh G, Maulucci G, Gombos I, Horváth I, Török Z, Péter M, Fodor E, Páli T, Benkő S, Parasassi T, De Spirito M, Harwood JL, Vígh L. Heat stress causes spatially-distinct membrane re-modelling in K562 leukemia cells. PLoS One 2011; 6:e21182. [PMID: 21698159 PMCID: PMC3116874 DOI: 10.1371/journal.pone.0021182] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Accepted: 05/22/2011] [Indexed: 02/05/2023] Open
Abstract
Cellular membranes respond rapidly to various environmental perturbations. Previously we showed that modulations in membrane fluidity achieved by heat stress (HS) resulted in pronounced membrane organization alterations which could be intimately linked to the expression and cellular distribution of heat shock proteins. Here we examine heat-induced membrane changes using several visualisation methods. With Laurdan two-photon microscopy we demonstrate that, in contrast to the enhanced formation of ordered domains in surface membranes, the molecular disorder is significantly elevated within the internal membranes of cells preexposed to mild HS. These results were compared with those obtained by anisotropy, fluorescence lifetime and electron paramagnetic resonance measurements. All probes detected membrane changes upon HS. However, the structurally different probes revealed substantially distinct alterations in membrane heterogeneity. These data call attention to the careful interpretation of results obtained with only a single label. Subtle changes in membrane microstructure in the decision-making of thermal cell killing could have potential application in cancer therapy.
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Affiliation(s)
- Gábor Balogh
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | | | - Imre Gombos
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Ibolya Horváth
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsolt Török
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Mária Péter
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Elfrieda Fodor
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Tibor Páli
- Institute of Biophysics, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Sándor Benkő
- First Department of Internal Medicine, Albert Szent-Györgyi Clinical Center, University of Szeged, Szeged, Hungary
| | | | - Marco De Spirito
- Istituto di Fisica, Universitá Cattolica Sacro Cuore, Rome, Italy
| | - John L. Harwood
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
- * E-mail: (LV); (JLH)
| | - László Vígh
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
- * E-mail: (LV); (JLH)
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40
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Chaves VE, Frasson D, Kawashita NH. Several agents and pathways regulate lipolysis in adipocytes. Biochimie 2011; 93:1631-40. [PMID: 21658426 DOI: 10.1016/j.biochi.2011.05.018] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 05/23/2011] [Indexed: 01/01/2023]
Abstract
Adipose tissue is the only tissue capable of hydrolyzing its stores of triacylglycerol (TAG) and of mobilizing fatty acids and glycerol in the bloodstream so that they can be used by other tissues. The full hydrolysis of TAG depends on the activity of three enzymes, adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL) and monoacylglycerol lipase, each of which possesses a distinct regulatory mechanism. Although more is known about HSL than about the other two enzymes, it has recently been shown that HLS and ATGL can be activated simultaneously, such that the mechanism that enables HSL to access the surface of lipid droplets also permits the stimulation of ATGL. The classical pathway of lipolysis activation in adipocytes is cAMP-dependent. The production of cAMP is modulated by G-protein-coupled receptors of the Gs/Gi family and cAMP degradation is regulated by phosphodiesterase. However, other pathways that activate TAG hydrolysis are currently under investigation. Lipolysis can also be started by G-protein-coupled receptors of the Gq family, through molecular mechanisms that involve phospholipase C, calmodulin and protein kinase C. There is also evidence that increased lipolytic activity in adipocytes occurs after stimulation of the mitogen-activated protein kinase pathway or after cGMP accumulation and activation of protein kinase G. Several agents contribute to the control of lipolysis in adipocytes by modulating the activity of HSL and ATGL. In this review, we have summarized the signalling pathways activated by several agents involved in the regulation of TAG hydrolysis in adipocytes.
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Affiliation(s)
- Valéria Ernestânia Chaves
- Department of Basic Sciences in Health, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil
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41
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German JB. Dietary lipids from an evolutionary perspective: sources, structures and functions. MATERNAL AND CHILD NUTRITION 2011; 7 Suppl 2:2-16. [PMID: 21366863 DOI: 10.1111/j.1740-8709.2011.00300.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lipids are a complex group of biomolecules whose precise functions remain poorly understood. As a result of this poor understanding, it is difficult to make mechanistically based recommendations for appropriate dietary intakes. It is equally difficult to develop methods that are capable of diagnosing functional impairments because of insufficiencies or excesses in particular fatty acids. Lipids are abundant building blocks of cellular membranes, supply components for lipid particle assembly and substrates for metabolic fuel, and provide a precursor pool for an astonishingly diverse range of signalling molecules. In each of these broad functions, the functional consequences of different structures of fatty acids are not fully understood. According to research on membrane functions through early evolution, docosahexaenoic acid provides two biophysical properties to membranes - accelerating the lateral motion of lipids and proteins within the plane of the membrane and simultaneously slowing the rate of diffusion/leakage of charged species across the plane of the membrane. The range of fatty acid structures used as substrates for assembly of either lipoproteins or milk fat globules is broad, yet the functional consequences of differences are not known. Different lipids signal into a remarkable range of biological processes. Saturated and monounsaturated fatty acids are becoming recognized as signal molecules in their own right. The complex composition of human milk lipids implies that diets with a diversity of fatty acids in complex lipid forms and structures is more beneficial than a narrow range of any particular group of fatty acids.
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Affiliation(s)
- J Bruce German
- Department of Food Science and Technology, University of California-Davis, CA 95616, USA.
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42
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Abstract
Lipid droplets are discrete organelles present in most cell types and organisms including bacteria, yeast, plants, insects and animals. Long considered as passive storage deposits, recent cell biology, proteomic and lipidomic analysis show that lipid droplets are dynamic organelles involved in multiple cellular functions. They have a central function in lipid distribution to different membrane-bound organelles and serve not only as main reservoirs of neutral lipids such as triglycerides and cholesterol but in addition, contain structural proteins, proteins involved in lipid synthesis and transmembrane proteins. A detailed model for how transmembrane proteins such as SNARE proteins can exist in lipid droplets is proposed.
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Affiliation(s)
- Fariba Kalantari
- The Research Institute of the McGill University Health Centre and the Department of Medicine, McGill University, Montreal, Quebec, Canada
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43
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Timmers S, de Vogel-van den Bosch J, Hesselink MKC, van Beurden D, Schaart G, Ferraz MJ, Losen M, Martinez-Martinez P, De Baets MH, Aerts JMFG, Schrauwen P. Paradoxical increase in TAG and DAG content parallel the insulin sensitizing effect of unilateral DGAT1 overexpression in rat skeletal muscle. PLoS One 2011; 6:e14503. [PMID: 21264296 PMCID: PMC3021516 DOI: 10.1371/journal.pone.0014503] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 12/15/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The involvement of muscle triacylglycerol (TAG) storage in the onset of insulin resistance is questioned and the attention has shifted towards inhibition of insulin signalling by the lipid intermediate diacylglycerol (DAG). The enzyme 1,2-acylCoA:diacylglyceroltransferase-1 (DGAT1) esterifies a fatty acyl-CoA on DAG to form TAG. Therefore, the aim of the present study was to investigate if unilateral overexpression of DGAT1 in adult rat Tibialis anterior (TA) muscle will increase conversion of the lipid intermediate DAG into TAG, thereby improving muscle insulin sensitivity. METHODOLOGY/PRINCIPAL FINDINGS The DGAT1 gene construct was injected in the left TA muscle of male rats on chow or high-fat (45% kcal) diet for three weeks, followed by application of one 800 V/cm and four 80 V/cm pulses, using the contralateral leg as sham-electroporated control. Seven days after electroporation, muscle specific insulin sensitivity was assessed with a hyperinsulinemic euglycemic clamp using 2-deoxy-[3H]glucose. Here, we provide evidence that unilateral overexpression of DGAT1 in TA muscle of male rats is associated with an increased rather than decreased DAG content. Strikingly, this increase in DAG content was accompanied by improved muscle insulin sensitivity. Interestingly, markers of muscle lipolysis and mitochondrial function were also increased in DGAT1 overexpressing muscle. CONCLUSIONS/SIGNIFICANCE We conclude that unilateral DGAT1 overexpression can rescue insulin sensitivity, possibly by increasing DAG and TAG turnover in skeletal muscle. In case of a proper balance between the supply and oxidation of fatty acids in skeletal muscle, the lipid intermediate DAG may not exert harmful effects on insulin signalling.
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Affiliation(s)
- Silvie Timmers
- Top Institute Food and Nutrition (TIFN), Wageningen, The Netherlands
- Department of Human Biology, Maastricht University, Maastricht, The Netherlands
| | - Johan de Vogel-van den Bosch
- Top Institute Food and Nutrition (TIFN), Wageningen, The Netherlands
- Department of Human Biology, Maastricht University, Maastricht, The Netherlands
| | - Matthijs K. C. Hesselink
- Human Movement Sciences, School for Nutrition, Toxicology and Metabolism (NUTRIM), Maastricht University, Maastricht, The Netherlands
| | - Denis van Beurden
- Department of Human Biology, Maastricht University, Maastricht, The Netherlands
| | - Gert Schaart
- Human Movement Sciences, School for Nutrition, Toxicology and Metabolism (NUTRIM), Maastricht University, Maastricht, The Netherlands
| | - Maria Joao Ferraz
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Mario Losen
- Department of Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Pilar Martinez-Martinez
- Department of Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Marc H. De Baets
- Department of Neuroscience, School of Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
| | - Johannes M. F. G. Aerts
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Patrick Schrauwen
- Top Institute Food and Nutrition (TIFN), Wageningen, The Netherlands
- Department of Human Biology, Maastricht University, Maastricht, The Netherlands
- * E-mail:
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Cho I, Horn L, Felix TM, Foster L, Gregory G, Starz-Gaiano M, Chambers MM, De Luca M, Leips J. Age- and diet-specific effects of variation at S6 kinase on life history, metabolic, and immune response traits in Drosophila melanogaster. DNA Cell Biol 2010; 29:473-85. [PMID: 20491566 DOI: 10.1089/dna.2009.0997] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Life history theory hypothesizes that genetically based variation in life history traits results from alleles that alter age-specific patterns of energy allocation among the competing demands of reproduction, storage, and maintenance. Despite the important role that alleles with age-specific effects must play in life history evolution, few naturally occurring alleles with age-specific effects on life history traits have been identified. A recent mapping study identified S6 kinase (S6k) as a candidate gene affecting lipid storage in Drosophila. S6k is in the target of rapamycin pathway, which regulates cell growth in response to nutrient availability and has also been implicated to influence many life history traits from fecundity to life span. In this article, we used quantitative complementation tests to examine the effect of allelic variation at S6k on a range of phenotypes associated with metabolism and fitness in an age-, diet-, and sex-specific manner. We found that alleles of S6k have pleiotropic effects on total protein levels, glycogen storage, life span, and the immune response and demonstrate that these allelic effects are age, diet, and sex specific. As many of the genes in the target of rapamycin pathway are evolutionarily conserved, our data suggest that genes in this pathway could play a pivotal role in life history evolution in a wide range of taxa.
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Affiliation(s)
- Irene Cho
- Department of Biological Sciences, University of Maryland Baltimore County , Baltimore, MD 21250, USA
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45
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Shaw CS, Clark J, Wagenmakers AJM. The effect of exercise and nutrition on intramuscular fat metabolism and insulin sensitivity. Annu Rev Nutr 2010; 30:13-34. [PMID: 20373917 DOI: 10.1146/annurev.nutr.012809.104817] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Intramuscular triacylglycerol (IMTG) is both a dynamic fat-storage depot that can expand during periods of elevated lipid availability and a fatty acid source that can be utilized during periods of increased energy expenditure in active individuals. Although many studies have investigated the lifestyle determinants of IMTG content, the results are far from consistent, and studies attempting to unravel the mechanisms behind IMTG metabolism are in their infancy. The limited evidence available suggests that the enzymes responsible for skeletal muscle lipolysis and IMTG synthesis play an important role in determining the fate of fatty acids and therefore the concentration of lipid metabolites and insulin sensitivity of skeletal muscle. This review provides a summary of current knowledge on the effects of acute and chronic exercise as well as energy intake and macronutrient composition of the diet upon the metabolism of IMTG and the implications for metabolic health.
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Affiliation(s)
- Christopher S Shaw
- School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT United Kingdom.
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46
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Abstract
PURPOSE OF REVIEW Lipid accumulation in nonadipose tissues is increasingly recognized to contribute to organ injury through a process termed lipotoxicity, but whether this process occurs in the kidney is still uncertain. This article briefly summarizes the normal role of lipids in renal physiology and the current evidence linking excess lipids and lipotoxicity to renal dysfunction. RECENT FINDINGS Evidence suggesting that renal lipid accumulation and lipotoxicity may lead to kidney dysfunction has mounted significantly over recent years. Abnormal renal lipid content has been described in a number of animal models and has been successfully manipulated using pharmacologic or genetic strategies. There is some heterogeneity among studies with regard to the mechanisms, consequences, and localization of lipid accumulation in the kidney, explainable at least in part by inherent differences between animal models. The relevance of these findings for human pathophysiology remains to be established. SUMMARY Current knowledge on renal lipid physiology and pathophysiology is insufficient, but provides a strong foundation and incentive for further exploration. The future holds significant challenges in this area, especially with regard to applicability of research findings to the human kidney in vivo, but also the opportunity to transform our understanding of an array of kidney disorders.
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Affiliation(s)
- Ion Alexandru Bobulescu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 775390-8885, USA.
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47
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Muoio DM. Intramuscular triacylglycerol and insulin resistance: guilty as charged or wrongly accused? Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:281-8. [PMID: 19958841 DOI: 10.1016/j.bbalip.2009.11.007] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2009] [Revised: 11/20/2009] [Accepted: 11/20/2009] [Indexed: 12/13/2022]
Abstract
The term lipotoxicity elicits visions of steatotic liver, fat laden skeletal muscles and engorged lipid droplets that spawn a number of potentially harmful intermediates that can wreak havoc on signal transduction and organ function. Prominent among these so-called lipotoxic mediators are signaling molecules such as long chain acyl-CoAs, ceramides and diacyglycerols; each of which is thought to engage serine kinases that disrupt the insulin signaling cascade, thereby causing insulin resistance. Defects in skeletal muscle fat oxidation have been implicated as a driving factor contributing to systemic lipid imbalance, whereas exercise-induced enhancement of oxidative potential is considered protective. The past decade of diabetes research has focused heavily on the foregoing scenario, and indeed the model is grounded in strong experimental evidence, albeit largely correlative. This review centers on mechanisms that connect lipid surplus to insulin resistance in skeletal muscle, as well as those that underlie the antilipotoxic actions of exercise. Emphasis is placed on recent studies that challenge accepted paradigms.
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Affiliation(s)
- Deborah M Muoio
- Sarah W. Stedman Nutrition and Metabolism Center and Department of Medicine, Duke University, Durham, NC 27710, USA.
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48
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Trauner M, Arrese M, Wagner M. Fatty liver and lipotoxicity. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:299-310. [PMID: 19857603 DOI: 10.1016/j.bbalip.2009.10.007] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 10/15/2009] [Accepted: 10/15/2009] [Indexed: 02/08/2023]
Abstract
Fatty liver disease comprises a spectrum ranging from simple steatosis to steatohepatitis which can progress to liver cirrhosis and hepatocellular cancer. Hepatic lipotoxicity may ensue when the hepatic capacity to utilize, store and export fatty acids (FA) as triglycerides is overwhelmed. Additional mechanisms of hepatic lipotoxicity include abnormal FA oxidation with formation of reactive oxygen species, disturbances in cellular membrane FA and phospholipid composition, alterations of cholesterol content and ceramide signalling. Lipotoxicity is a key factor for the progression of fatty liver disease by inducing hepatocellular death, activating Kupffer cells and an inflammatory response, impairing hepatic insulin signalling resulting in insulin resistance, and activation of a fibrogenic response in hepatic stellate cells that can ultimately lead to cirrhosis. Therefore, the concept of hepatic lipotoxicity should be considered in future therapeutic concepts for fatty liver disease.
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Affiliation(s)
- Michael Trauner
- Laboratory of Experimental and Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria.
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