1
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Coates HW, Nguyen TB, Du X, Olzomer EM, Farrell R, Byrne FL, Yang H, Brown AJ. The constitutively active form of a key cholesterol synthesis enzyme is lipid droplet-localized and upregulated in endometrial cancer tissues. J Biol Chem 2024; 300:107232. [PMID: 38537696 PMCID: PMC11061744 DOI: 10.1016/j.jbc.2024.107232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 03/18/2024] [Indexed: 04/26/2024] Open
Abstract
Cholesterol is essential for both normal cell viability and cancer cell proliferation. Aberrant activity of squalene monooxygenase (SM, also known as squalene epoxidase), the rate-limiting enzyme of the committed cholesterol synthesis pathway, is accordingly implicated in a growing list of cancers. We previously reported that hypoxia triggers the truncation of SM to a constitutively active form, thus preserving sterol synthesis during oxygen shortfalls. Here, we show SM truncation is upregulated and correlates with the magnitude of hypoxia in endometrial cancer tissues, supporting the in vivo relevance of our earlier work. To further investigate the pathophysiological consequences of SM truncation, we examined its lipid droplet-localized pool using complementary immunofluorescence and cell fractionation approaches and found that it exclusively comprises the truncated enzyme. This partitioning is facilitated by the loss of an endoplasmic reticulum-embedded region at the SM N terminus, whereas the catalytic domain containing membrane-associated C-terminal helices is spared. Moreover, we determined multiple amphipathic helices contribute to the lipid droplet localization of truncated SM. Taken together, our results expand on the striking differences between the two forms of SM and suggest upregulated truncation may contribute to SM-related oncogenesis.
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Affiliation(s)
- Hudson W Coates
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Tina B Nguyen
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Ellen M Olzomer
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Rhonda Farrell
- Chris O'Brien Lifehouse, Camperdown, New South Wales, Australia; Prince of Wales Private Hospital, Randwick, New South Wales, Australia
| | - Frances L Byrne
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia
| | - Andrew J Brown
- School of Biotechnology and Biomolecular Sciences, UNSW, Sydney, New South Wales, Australia.
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2
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Kohlmayr JM, Grabner GF, Nusser A, Höll A, Manojlović V, Halwachs B, Masser S, Jany-Luig E, Engelke H, Zimmermann R, Stelzl U. Mutational scanning pinpoints distinct binding sites of key ATGL regulators in lipolysis. Nat Commun 2024; 15:2516. [PMID: 38514628 PMCID: PMC10958042 DOI: 10.1038/s41467-024-46937-x] [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: 05/26/2023] [Accepted: 03/14/2024] [Indexed: 03/23/2024] Open
Abstract
ATGL is a key enzyme in intracellular lipolysis and plays an important role in metabolic and cardiovascular diseases. ATGL is tightly regulated by a known set of protein-protein interaction partners with activating or inhibiting functions in the control of lipolysis. Here, we use deep mutational protein interaction perturbation scanning and generate comprehensive profiles of single amino acid variants that affect the interactions of ATGL with its regulatory partners: CGI-58, G0S2, PLIN1, PLIN5 and CIDEC. Twenty-three ATGL amino acid variants yield a specific interaction perturbation pattern when validated in co-immunoprecipitation experiments in mammalian cells. We identify and characterize eleven highly selective ATGL switch mutations which affect the interaction of one of the five partners without affecting the others. Switch mutations thus provide distinct interaction determinants for ATGL's key regulatory proteins at an amino acid resolution. When we test triglyceride hydrolase activity in vitro and lipolysis in cells, the activity patterns of the ATGL switch variants trace to their protein interaction profile. In the context of structural data, the integration of variant binding and activity profiles provides insights into the regulation of lipolysis and the impact of mutations in human disease.
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Affiliation(s)
- Johanna M Kohlmayr
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Gernot F Grabner
- Institute of Molecular Biosciences, Biochemistry, University of Graz, Graz, Austria
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Anna Nusser
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Anna Höll
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Verina Manojlović
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Bettina Halwachs
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Sarah Masser
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Evelyne Jany-Luig
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Hanna Engelke
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Robert Zimmermann
- Institute of Molecular Biosciences, Biochemistry, University of Graz, Graz, Austria
- Field of Excellence BioHealth - University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Ulrich Stelzl
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria.
- Field of Excellence BioHealth - University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
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3
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Awad D, Cao PHA, Pulliam TL, Spradlin M, Subramani E, Tellman TV, Ribeiro CF, Muzzioli R, Jewell BE, Pakula H, Ackroyd JJ, Murray MM, Han JJ, Leng M, Jain A, Piyarathna B, Liu J, Song X, Zhang J, Klekers AR, Drake JM, Ittmann MM, Coarfa C, Piwnica-Worms D, Farach-Carson MC, Loda M, Eberlin LS, Frigo DE. Adipose Triglyceride Lipase Is a Therapeutic Target in Advanced Prostate Cancer That Promotes Metabolic Plasticity. Cancer Res 2024; 84:703-724. [PMID: 38038968 PMCID: PMC10939928 DOI: 10.1158/0008-5472.can-23-0555] [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: 03/21/2023] [Revised: 10/09/2023] [Accepted: 11/28/2023] [Indexed: 12/02/2023]
Abstract
Lipid metabolism plays a central role in prostate cancer. To date, the major focus has centered on de novo lipogenesis and lipid uptake in prostate cancer, but inhibitors of these processes have not benefited patients. A better understanding of how cancer cells access lipids once they are created or taken up and stored could uncover more effective strategies to perturb lipid metabolism and treat patients. Here, we identified that expression of adipose triglyceride lipase (ATGL), an enzyme that controls lipid droplet homeostasis and a previously suspected tumor suppressor, correlates with worse overall survival in men with advanced, castration-resistant prostate cancer (CRPC). Molecular, genetic, or pharmacologic inhibition of ATGL impaired human and murine prostate cancer growth in vivo and in cell culture or organoids under conditions mimicking the tumor microenvironment. Mass spectrometry imaging demonstrated that ATGL profoundly regulates lipid metabolism in vivo, remodeling membrane composition. ATGL inhibition induced metabolic plasticity, causing a glycolytic shift that could be exploited therapeutically by cotargeting both metabolic pathways. Patient-derived phosphoproteomics identified ATGL serine 404 as a target of CAMKK2-AMPK signaling in CRPC cells. Mutation of serine 404 did not alter the lipolytic activity of ATGL but did decrease CRPC growth, migration, and invasion, indicating that noncanonical ATGL activity also contributes to disease progression. Unbiased immunoprecipitation/mass spectrometry suggested that mutation of serine 404 not only disrupts existing ATGL protein interactions but also leads to new protein-protein interactions. Together, these data nominate ATGL as a therapeutic target for CRPC and provide insights for future drug development and combination therapies. SIGNIFICANCE ATGL promotes prostate cancer metabolic plasticity and progression through both lipase-dependent and lipase-independent activity, informing strategies to target ATGL and lipid metabolism for cancer treatment.
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Affiliation(s)
- Dominik Awad
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Pham Hong Anh Cao
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Thomas L. Pulliam
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Meredith Spradlin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas, USA
- Department of Surgery, Baylor College of Medicine, Houston, Texas, USA
| | - Elavarasan Subramani
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Tristen V. Tellman
- The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, TX, USA
- Department of Diagnostic and Biomedical Sciences, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX, USA
| | - Caroline F. Ribeiro
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Riccardo Muzzioli
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Brittany E. Jewell
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Hubert Pakula
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Jeffrey J. Ackroyd
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mollianne M. Murray
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jenny J. Han
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mei Leng
- Mass Spectrometry Proteomics Core, Baylor College of Medicine, Houston, TX, USA
| | - Antrix Jain
- Mass Spectrometry Proteomics Core, Baylor College of Medicine, Houston, TX, USA
| | - Badrajee Piyarathna
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
| | - Jingjing Liu
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Xingzhi Song
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jianhua Zhang
- Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Albert R. Klekers
- Department of Abdominal Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Justin M. Drake
- Departments of Pharmacology and Urology, University of Minnesota, Minneapolis, MN, USA
- Masonic Cancer Center, University of Minnesota-Twin Cities, MN, USA
| | - Michael M. Ittmann
- Departments of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Dan L. Duncan Cancer Center, Houston, TX, USA
- Michael E. DeBakey Veterans Affairs Medical Center, Houston, TX, USA
- Michael E. DeBakey Department of Surgery, Houston, TX, USA
| | - Cristian Coarfa
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
| | - David Piwnica-Worms
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mary C. Farach-Carson
- Department of Diagnostic and Biomedical Sciences, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX, USA
| | - Massimo Loda
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Livia S. Eberlin
- Department of Surgery, Baylor College of Medicine, Houston, Texas, USA
| | - Daniel E. Frigo
- Department of Cancer Systems Imaging, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
- Center for Nuclear Receptors and Cell Signaling, University of Houston, Houston, TX, USA
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
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4
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Abstract
Lipophagy is a central cellular process for providing the cell with a readily utilized, high energy source of neutral lipids. Since its discovery over a decade ago, we are just starting to understand the molecular components that drive lipophagy, how it is activated in response to nutrient availability, and its potential as a therapeutic target in disease. In this Cell Science at a Glance article and the accompanying poster, we first provide a brief overview of the different structural and enzymatic proteins that comprise the lipid droplet (LD) proteome and reside within the limiting phospholipid monolayer of this complex organelle. We then highlight key players in the catabolic breakdown of LDs during the functionally linked lipolysis and lipophagy processes. Finally, we discuss what is currently known about macro- and micro-lipophagy based on findings in yeast, mammalian and other model systems, and how impairment of these important functions can lead to disease states.
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Affiliation(s)
- Micah B Schott
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, 985870 Nebraska Medical Center, Omaha, NE 68198, USA
| | - Cody N Rozeveld
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, 985870 Nebraska Medical Center, Omaha, NE 68198, USA
| | - Shaun G Weller
- Department of Biochemistry and Molecular Biology and the Center for Digestive Diseases, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA
| | - Mark A McNiven
- Department of Biochemistry and Molecular Biology and the Center for Digestive Diseases, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA
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5
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Yue F, Oprescu SN, Qiu J, Gu L, Zhang L, Chen J, Narayanan N, Deng M, Kuang S. Lipid droplet dynamics regulate adult muscle stem cell fate. Cell Rep 2022; 38:110267. [PMID: 35045287 PMCID: PMC9127130 DOI: 10.1016/j.celrep.2021.110267] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 08/31/2021] [Accepted: 12/21/2021] [Indexed: 11/03/2022] Open
Abstract
The lipid droplet (LD) is a central hub for fatty acid metabolism in cells. Here we define the dynamics and explore the role of LDs in skeletal muscle satellite cells (SCs), a stem cell population responsible for muscle regeneration. In newly divided SCs, LDs are unequally distributed in sister cells exhibiting asymmetric cell fates, as the LDLow cell self-renews while the LDHigh cell commits to differentiation. When transplanted into regenerating muscles, LDLow cells outperform LDHigh cells in self-renewal and regeneration in vivo. Pharmacological inhibition of LD biogenesis or genetic inhibition of LD catabolism through knockout of Pnpla2 (encoding ATGL, the rate-limiting enzyme for lipolysis) disrupts cell fate homeostasis and impairs the regenerative capacity of SCs. Dysfunction of Pnpla2-null SCs is associated with energy insufficiency and oxidative stress that can be partially rescued by antioxidant (N-acetylcysteine) treatment. These results establish a direct link between LD dynamics and stem cell fate determination.
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Affiliation(s)
- Feng Yue
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA.
| | - Stephanie N Oprescu
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA; Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Jiamin Qiu
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Lijie Gu
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Lijia Zhang
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Jingjuan Chen
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Naagarajan Narayanan
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Meng Deng
- Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Shihuan Kuang
- Department of Animal Sciences, Purdue University, West Lafayette, IN 47907, USA; Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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6
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Lundquist PK. Tracking subplastidic localization of carotenoid metabolic enzymes with proteomics. Methods Enzymol 2022; 671:327-350. [DOI: 10.1016/bs.mie.2022.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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7
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Li L, Wang J, Li D, Zhang H. Morphine increases myocardial triacylglycerol through regulating adipose triglyceride lipase S406 phosphorylation. Life Sci 2021; 283:119866. [PMID: 34352257 DOI: 10.1016/j.lfs.2021.119866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 10/20/2022]
Abstract
AIMS Morphine, a commonly used drug for anesthesia, affects lipid metabolism in different tissues, but the mechanism is currently unclear. Adipose triglyceride lipase (ATGL) is the rate-limiting enzyme responsible for the first step of triglyceride (TG) hydrolysis. Here we aim to investigate whether ATGL phosphorylation is involved in morphine-induced TG accumulation. MAIN METHODS Oil red O staining and TG content analysis were used to detect the effect of morphine on lipid storage. A series of ATGL phosphoamino acid site mutant plasmids were constructed by gene synthesis and transfected to HL-1 cells to evaluate the phosphorylation levels of ATGL phosphoamino acid in morphine-treated HL-1 cells with immunoprecipitation and immunoblotting assay. KEY FINDINGS Morphine acute treatment induced excessive accumulation of TG and decreased the phosphorylation level of ATGL Ser406 in HL-1 cells. Of note, the phosphorylation positive mutation of ATGL Ser406 to aspartic acid effectively reversed morphine-induced excessive accumulation of TG in HL-1 cells. SIGNIFICANCE This discovery will help to fully understand the lipid regulation function of morphine in a new scope. In addition, it will expand the phosphorylation research of ATGL more comprehensively and provide powerful clues for lipid metabolism regulation.
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Affiliation(s)
- Linghai Li
- Department of Anesthesiology, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, 101149, Beijing, China.
| | - Jinghui Wang
- Department of Medical Oncology, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, 101149 Beijing, China
| | - Ding Li
- Department of Anesthesiology, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, 101149, Beijing, China
| | - Huina Zhang
- Beijing An Zhen Hospital, Capital Medical University, Beijing Institute of Heart Lung and Blood Vessel Disease, 100029 Beijing, China.
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8
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Ma X, Zhi Z, Zhang S, Zhou C, Mechler A, Liu P. Validating an artificial organelle: Studies of lipid droplet-specific proteins on adiposome platform. iScience 2021; 24:102834. [PMID: 34368652 PMCID: PMC8326204 DOI: 10.1016/j.isci.2021.102834] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/28/2021] [Accepted: 07/08/2021] [Indexed: 10/25/2022] Open
Abstract
New strategies are urgently needed to characterize the functions of the lipid droplet (LD). Here, adiposome, an artificial LD mimetic platform, was validated by comparative in vitro bioassays. Scatchard analysis found that the binding of perilipin 2 (PLIN2) to the adiposome surface was saturable. Phosphatidylinositol (PtdIns) was found to inhibit PLIN2 binding while it did not impede perilipin 3 (PLIN3). Structural analysis combined with mutagenesis revealed that the 73rd glutamic acid of PLIN2 is significant for the effect of PtdIns on the PLIN2 binding. Furthermore, adiposome was also found to be an ideal platform for in situ enzymatic activity measurement of adipose triglyceride lipase (ATGL). The significant serine mutants of ATGL were found to cause the loss of lipase activity. Our study demonstrates the adiposome as a powerful, manipulatable model system that mimics the function of LD for binding and enzymatic activity studies of LD proteins in vitro.
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Affiliation(s)
- Xuejing Ma
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zelun Zhi
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, 3086, Australia
| | - Shuyan Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Chang Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | - Adam Mechler
- Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, 3086, Australia
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
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9
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Wei W, Li Y, Li Y, Li D. Adipose-specific knockout of ubiquitin-conjugating enzyme E2L6 (Ube2l6) reduces diet-induced obesity, insulin resistance, and hepatic steatosis. J Pharmacol Sci 2020; 145:327-334. [PMID: 33712284 DOI: 10.1016/j.jphs.2020.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 12/10/2020] [Accepted: 12/28/2020] [Indexed: 12/13/2022] Open
Abstract
Ubiquitin/ISG15-conjugating enzyme E2 L6 (UBE2L6/Ube2l6) catalyzes protein ISGylation and ubiquitylation, post-translational modifications which regulate protein stability. Ube2l6 plays a role in promoting in vitro adipogenesis; however, its mechanism(s) of action and in vivo effects remain unknown. Here, we discovered that UBE2L6 levels were upregulated, and UBE2L6 and adipose triglyceride lipase (ATGL/Atgl) levels were negatively correlated, in white adipose tissue (WAT) from obese humans and obese mice. Therefore, we employed adipose-specific Ube2l6 knockout (Ube2l6AKO) mice and age-matched Ube2l6flox/flox controls to assess adipocyte Ube2l6's role in high-fat diet (HFD)-induced obesity, insulin resistance, and hepatic steatosis. HFD-fed Ube2l6AKO mice displayed lower subcutaneous and visceral WAT mass levels relative to controls. HFD-fed Ube2l6AKO mice also showed WAT adipocyte hypoplasia and hypotrophy as well as enhanced whole-body metabolic activity relative to controls. Furthermore, glucose intolerance, insulin resistance, compensatory hyperinsulinemia, hypercholesterolemia, and hepatic steatosis were lower in HFD-fed Ube2l6AKO mice as compared to controls. Mechanistically, we found that Atgl protein expression and Atgl-mediated lipolysis were negatively regulated by Ube2l6's promotion of Atgl protein ubiquitylation. Collectively, adipocyte Ube2l6 functions as a negative regulator of Atgl protein stability and, consequently, promotes HFD-induced obesity, insulin resistance, and hepatic steatosis.
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Affiliation(s)
- Weiping Wei
- Department of Endocrinology, Hainan General Hospital, Haikou, China
| | - Yunqian Li
- Hainan Provincial Healthcare Center, Hainan General Hospital, Haikou, China
| | - Yongyong Li
- Chuangxu Institute of Life Science, Chongqing, China
| | - Daoyuan Li
- Department of Urological Surgery, Hainan General Hospital, Haikou, China.
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10
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de Oliveira C, Khatua B, Noel P, Kostenko S, Bag A, Balakrishnan B, Patel KS, Guerra AA, Martinez MN, Trivedi S, McCullough A, Lam-Himlin DM, Navina S, Faigel DO, Fukami N, Pannala R, Phillips AE, Papachristou GI, Kershaw EE, Lowe ME, Singh VP. Pancreatic triglyceride lipase mediates lipotoxic systemic inflammation. J Clin Invest 2020; 130:1931-1947. [PMID: 31917686 DOI: 10.1172/jci132767] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 01/03/2020] [Indexed: 12/22/2022] Open
Abstract
Visceral adipose tissue plays a critical role in numerous diseases. Although imaging studies often show adipose involvement in abdominal diseases, their outcomes may vary from being a mild self-limited illness to one with systemic inflammation and organ failure. We therefore compared the pattern of visceral adipose injury during acute pancreatitis and acute diverticulitis to determine its role in organ failure. Acute pancreatitis-associated adipose tissue had ongoing lipolysis in the absence of adipocyte triglyceride lipase (ATGL). Pancreatic lipase injected into mouse visceral adipose tissue hydrolyzed adipose triglyceride and generated excess nonesterified fatty acids (NEFAs), which caused organ failure in the absence of acute pancreatitis. Pancreatic triglyceride lipase (PNLIP) increased in adipose tissue during pancreatitis and entered adipocytes by multiple mechanisms, hydrolyzing adipose triglyceride and generating excess NEFAs. During pancreatitis, obese PNLIP-knockout mice, unlike obese adipocyte-specific ATGL knockouts, had lower visceral adipose tissue lipolysis, milder inflammation, less severe organ failure, and improved survival. PNLIP-knockout mice, unlike ATGL knockouts, were protected from adipocyte-induced pancreatic acinar injury without affecting NEFA signaling or acute pancreatitis induction. Therefore, during pancreatitis, unlike diverticulitis, PNLIP leaking into visceral adipose tissue can cause excessive visceral adipose tissue lipolysis independently of adipocyte-autonomous ATGL, and thereby worsen organ failure.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Ann McCullough
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Scottsdale, Arizona, USA
| | - Dora M Lam-Himlin
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Scottsdale, Arizona, USA
| | | | | | | | | | - Anna Evans Phillips
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | | | - Erin E Kershaw
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Mark E Lowe
- Department of Pediatrics, Washington University in St. Louis, St. Louis, Missouri, USA
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11
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Samukawa M, Nakamura N, Hirano M, Morikawa M, Sakata H, Nishino I, Izumi R, Suzuki N, Kuroda H, Shiga K, Saigoh K, Aoki M, Kusunoki S. Neutral Lipid Storage Disease Associated with the PNPLA2 Gene: Case Report and Literature Review. Eur Neurol 2020; 83:317-322. [PMID: 32564019 DOI: 10.1159/000508346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 04/20/2020] [Indexed: 11/19/2022]
Abstract
Mutations in the PNPLA2 gene cause neutral lipid storage disease with myopathy (NLSDM) or triglyceride deposit cardiomyovasculopathy. We report a detailed case study of a 53-year-old man with NLSDM. The PNPLA2 gene was analyzed according to the reported method. We summarized the clinical, laboratory, and genetic information of 56 patients, including our patient and 55 other reported patients with homozygous or compound heterozygous mutations in the PNPLA2 gene. We found a novel homozygous mutation (c.194delC) in the PNPLA2 gene that resulted in frameshift. The patient suffered from normal-tension glaucoma and pulmonary cysts, symptoms that are relatively common in the elderly but were not previously reported for this disease. Our summary confirmed that Jordan's anomaly, polymorphonuclear leukocytes with lipid accumulation, was the most consistent finding of this disease. Because this disease is potentially treatable, our results may help rapid and correct diagnosis.
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Affiliation(s)
- Makoto Samukawa
- Department of Neurology, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Naoko Nakamura
- Department of Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Makito Hirano
- Department of Neurology, Kindai University, Faculty of Medicine, Osaka, Japan,
| | - Miyuki Morikawa
- Department of Neurology, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Hanami Sakata
- Department of Neurology, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Rumiko Izumi
- Department of Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Naoki Suzuki
- Department of Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hiroshi Kuroda
- Department of Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kensuke Shiga
- Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Neurology, Matsushita Memorial Hospital, Osaka, Japan
| | - Kazumasa Saigoh
- Department of Neurology, Kindai University, Faculty of Medicine, Osaka, Japan
| | - Masashi Aoki
- Department of Neurology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Susumu Kusunoki
- Department of Neurology, Kindai University, Faculty of Medicine, Osaka, Japan
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12
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Vieyres G, Reichert I, Carpentier A, Vondran FWR, Pietschmann T. The ATGL lipase cooperates with ABHD5 to mobilize lipids for hepatitis C virus assembly. PLoS Pathog 2020; 16:e1008554. [PMID: 32542055 PMCID: PMC7316345 DOI: 10.1371/journal.ppat.1008554] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 06/25/2020] [Accepted: 04/15/2020] [Indexed: 12/12/2022] Open
Abstract
Lipid droplets are essential cellular organelles for storage of fatty acids and triglycerides. The hepatitis C virus (HCV) translocates several of its proteins onto their surface and uses them for production of infectious progeny. We recently reported that the lipid droplet-associated α/β hydrolase domain-containing protein 5 (ABHD5/CGI-58) participates in HCV assembly by mobilizing lipid droplet-associated lipids. However, ABHD5 itself has no lipase activity and it remained unclear how ABHD5 mediates lipolysis critical for HCV assembly. Here, we identify adipose triglyceride lipase (ATGL) as ABHD5 effector and new host factor involved in the hepatic lipid droplet degradation as well as in HCV and lipoprotein morphogenesis. Modulation of ATGL protein expression and lipase activity controlled lipid droplet lipolysis and virus production. ABHD4 is a paralog of ABHD5 unable to activate ATGL or support HCV assembly and lipid droplet lipolysis. Grafting ABHD5 residues critical for activation of ATGL onto ABHD4 restored the interaction between lipase and co-lipase and bestowed the pro-viral and lipolytic functions onto the engineered protein. Congruently, mutation of the predicted ABHD5 protein interface to ATGL ablated ABHD5 functions in lipid droplet lipolysis and HCV assembly. Interestingly, minor alleles of ABHD5 and ATGL associated with neutral lipid storage diseases in human, are also impaired in lipid droplet lipolysis and their pro-viral functions. Collectively, these results show that ABHD5 cooperates with ATGL to mobilize triglycerides for HCV infectious virus production. Moreover, viral manipulation of lipid droplet homeostasis via the ABHD5-ATGL axis, akin to natural genetic variation in these proteins, emerges as a possible mechanism by which chronic HCV infection causes liver steatosis.
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Affiliation(s)
- Gabrielle Vieyres
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
- * E-mail: (GV); (TP)
| | - Isabelle Reichert
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
| | - Arnaud Carpentier
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
| | - Florian W. R. Vondran
- German Centre for Infection Research (DZIF), partner site Hannover-Braunschweig, Germany
- ReMediES, Department of General, Visceral and Transplant Surgery, Hannover Medical School, Hannover, Germany
| | - Thomas Pietschmann
- Institute of Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research; a joint venture between the Medical School Hannover (MHH) and the Helmholtz Centre for Infection Research (HZI), Hannover, Germany
- German Centre for Infection Research (DZIF), partner site Hannover-Braunschweig, Germany
- * E-mail: (GV); (TP)
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13
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Hofer P, Taschler U, Schreiber R, Kotzbeck P, Schoiswohl G. The Lipolysome-A Highly Complex and Dynamic Protein Network Orchestrating Cytoplasmic Triacylglycerol Degradation. Metabolites 2020; 10:E147. [PMID: 32290093 PMCID: PMC7240967 DOI: 10.3390/metabo10040147] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/03/2020] [Accepted: 04/08/2020] [Indexed: 12/25/2022] Open
Abstract
The catabolism of intracellular triacylglycerols (TAGs) involves the activity of cytoplasmic and lysosomal enzymes. Cytoplasmic TAG hydrolysis, commonly termed lipolysis, is catalyzed by the sequential action of three major hydrolases, namely adipose triglyceride lipase, hormone-sensitive lipase, and monoacylglycerol lipase. All three enzymes interact with numerous protein binding partners that modulate their activity, cellular localization, or stability. Deficiencies of these auxiliary proteins can lead to derangements in neutral lipid metabolism and energy homeostasis. In this review, we summarize the composition and the dynamics of the complex lipolytic machinery we like to call "lipolysome".
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Affiliation(s)
- Peter Hofer
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Ulrike Taschler
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
| | - Petra Kotzbeck
- Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria;
| | - Gabriele Schoiswohl
- Institute of Molecular Biosciences, University of Graz, 8010 Graz, Austria; (P.H.); (U.T.); (R.S.)
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14
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Schott MB, Weller SG, Schulze RJ, Krueger EW, Drizyte-Miller K, Casey CA, McNiven MA. Lipid droplet size directs lipolysis and lipophagy catabolism in hepatocytes. J Cell Biol 2019; 218:3320-3335. [PMID: 31391210 PMCID: PMC6781454 DOI: 10.1083/jcb.201803153] [Citation(s) in RCA: 162] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 09/18/2018] [Accepted: 07/17/2019] [Indexed: 12/20/2022] Open
Abstract
Lipid droplet (LD) catabolism in hepatocytes is mediated by a combination of lipolysis and a selective autophagic mechanism called lipophagy, but the relative contributions of these seemingly distinct pathways remain unclear. We find that inhibition of lipolysis, lipophagy, or both resulted in similar overall LD content but dramatic differences in LD morphology. Inhibition of the lipolysis enzyme adipose triglyceride lipase (ATGL) resulted in large cytoplasmic LDs, whereas lysosomal inhibition caused the accumulation of numerous small LDs within the cytoplasm and degradative acidic vesicles. Combined inhibition of ATGL and LAL resulted in large LDs, suggesting that lipolysis targets these LDs upstream of lipophagy. Consistent with this, ATGL was enriched in larger-sized LDs, whereas lipophagic vesicles were restricted to small LDs as revealed by immunofluorescence, electron microscopy, and Western blot of size-separated LDs. These findings provide new evidence indicating a synergistic relationship whereby lipolysis targets larger-sized LDs to produce both size-reduced and nascently synthesized small LDs that are amenable for lipophagic internalization.
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Affiliation(s)
- Micah B Schott
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Shaun G Weller
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Ryan J Schulze
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Eugene W Krueger
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Kristina Drizyte-Miller
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Carol A Casey
- Department of Internal Medicine and Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE.,Research Service, Department of Veterans Affairs, Nebraska-Western Iowa Health Care System, Omaha, NE
| | - Mark A McNiven
- Department of Biochemistry and Molecular Biology, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
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15
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Wang Y, Kory N, BasuRay S, Cohen JC, Hobbs HH. PNPLA3, CGI-58, and Inhibition of Hepatic Triglyceride Hydrolysis in Mice. Hepatology 2019; 69:2427-2441. [PMID: 30802989 PMCID: PMC6563103 DOI: 10.1002/hep.30583] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 02/16/2019] [Indexed: 12/12/2022]
Abstract
A variant (148M) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) is a major risk factor for fatty liver disease. Despite its clinical importance, the pathogenic mechanism linking the variant to liver disease remains poorly defined. Previously, we showed that PNPLA3(148M) accumulates to high levels on hepatic lipid droplets (LDs). Here we examined the effect of that accumulation on triglyceride (TG) hydrolysis by adipose triglyceride lipase (ATGL), the major lipase in the liver. As expected, overexpression of ATGL in cultured hepatoma (HuH-7) cells depleted the cells of LDs, but unexpectedly, co-expression of PNPLA3(wild type [WT] or 148M) with ATGL inhibited that depletion. The inhibitory effect of PNPLA3 was not caused by the displacement of ATGL from LDs. We tested the hypothesis that PNPLA3 interferes with ATGL activity by interacting with its cofactor, comparative gene identification-58 (CGI-58). Evidence supporting such an interaction came from two findings. First, co-expression of PNPLA3 and CGI-58 resulted in LD depletion in cultured cells, but expression of PNPLA3 alone did not. Second, PNPLA3 failed to localize to hepatic LDs in liver-specific Cgi-58 knockout (KO) mice. Moreover, overexpression of PNPLA3(148M) increased hepatic TG levels in WT, but not in Cgi-58 KO mice. Thus, the pro-steatotic effects of PNPLA3 required the presence of CGI-58. Co-immunoprecipitation and pulldown experiments in livers of mice and in vitro using purified proteins provided evidence that PNPLA3 and CGI-58 can interact directly. Conclusion: Taken together, these findings are consistent with a model in which PNPLA3(148M) promotes steatosis by CGI-58-dependent inhibition of ATGL on LDs.
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Affiliation(s)
- Yang Wang
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Nora Kory
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Soumik BasuRay
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Jonathan C. Cohen
- Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTX,The Center for Human NutritionUniversity of Texas Southwestern Medical CenterDallas TX
| | - Helen H. Hobbs
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX,Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTX,Howard Hughes Medical InstituteUniversity of Texas Southwestern Medical CenterDallasTX
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16
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Adipose HuR protects against diet-induced obesity and insulin resistance. Nat Commun 2019; 10:2375. [PMID: 31147543 PMCID: PMC6542850 DOI: 10.1038/s41467-019-10348-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 05/06/2019] [Indexed: 02/07/2023] Open
Abstract
Human antigen R (HuR) is a member of the Hu family of RNA-binding proteins and is involved in many physiological processes. Obesity, as a worldwide healthcare problem, has attracted more and more attention. To investigate the role of adipose HuR, we generate adipose-specific HuR knockout (HuRAKO) mice. As compared with control mice, HuRAKO mice show obesity when induced with a high-fat diet, along with insulin resistance, glucose intolerance, hypercholesterolemia and increased inflammation in adipose tissue. The obesity of HuRAKO mice is attributed to adipocyte hypertrophy in white adipose tissue due to decreased expression of adipose triglyceride lipase (ATGL). HuR positively regulates ATGL expression by promoting the mRNA stability and translation of ATGL. Consistently, the expression of HuR in adipose tissue is reduced in obese humans. This study suggests that adipose HuR may be a critical regulator of ATGL expression and lipolysis and thereby controls obesity and metabolic syndrome. Human antigen R (HuR) is a RNA-binding protein. Here the authors investigate its role in adipose tissue and find that it protects mice from diet-induced obesity, prevents adipocyte hypertrophy, and promotes lipolysis, which may at least in part be due to HuR-dependent ATGL mRNA stability regulation demonstrated in-vitro.
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17
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Of mice and men: The physiological role of adipose triglyceride lipase (ATGL). Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:880-899. [PMID: 30367950 PMCID: PMC6439276 DOI: 10.1016/j.bbalip.2018.10.008] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/18/2018] [Accepted: 10/19/2018] [Indexed: 12/12/2022]
Abstract
Adipose triglyceride lipase (ATGL) has been discovered 14 years ago and revised our view on intracellular triglyceride (TG) mobilization – a process termed lipolysis. ATGL initiates the hydrolysis of TGs to release fatty acids (FAs) that are crucial energy substrates, precursors for the synthesis of membrane lipids, and ligands of nuclear receptors. Thus, ATGL is a key enzyme in whole-body energy homeostasis. In this review, we give an update on how ATGL is regulated on the transcriptional and post-transcriptional level and how this affects the enzymes' activity in the context of neutral lipid catabolism. In depth, we highlight and discuss the numerous physiological functions of ATGL in lipid and energy metabolism. Over more than a decade, different genetic mouse models lacking or overexpressing ATGL in a cell- or tissue-specific manner have been generated and characterized. Moreover, pharmacological studies became available due to the development of a specific murine ATGL inhibitor (Atglistatin®). The identification of patients with mutations in the human gene encoding ATGL and their disease spectrum has underpinned the importance of ATGL in humans. Together, mouse models and human data have advanced our understanding of the physiological role of ATGL in lipid and energy metabolism in adipose and non-adipose tissues, and of the pathophysiological consequences of ATGL dysfunction in mice and men. Summary of mouse models with genetic or pharmacological manipulation of ATGL. Summary of patients with mutations in the human gene encoding ATGL. In depth discussion of the role of ATGL in numerous physiological processes in mice and men.
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18
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Bolsoni-Lopes A, Alonso-Vale MIC. Lipolysis and lipases in white adipose tissue - An update. ARCHIVES OF ENDOCRINOLOGY AND METABOLISM 2017; 59:335-42. [PMID: 26331321 DOI: 10.1590/2359-3997000000067] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 04/22/2015] [Indexed: 11/22/2022]
Abstract
Lipolysis is defined as the sequential hydrolysis of triacylglycerol (TAG) stored in cell lipid droplets. For many years, it was believed that hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MGL) were the main enzymes catalyzing lipolysis in the white adipose tissue. Since the discovery of adipose triglyceride lipase (ATGL) in 2004, many studies were performed to investigate and characterize the actions of this lipase, as well as of other proteins and possible regulatory mechanisms involved, which reformulated the concept of lipolysis. Novel findings from these studies include the identification of lipolytic products as signaling molecules regulating important metabolic processes in many non-adipose tissues, unveiling a previously underestimated aspect of lipolysis. Thus, we present here an updated review of concepts and regulation of white adipocyte lipolysis with a special emphasis in its role in metabolism homeostasis and as a source of important signaling molecules.
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Affiliation(s)
- Andressa Bolsoni-Lopes
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, BR
| | - Maria Isabel C Alonso-Vale
- Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema, SP, BR
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19
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Meyers A, Weiskittel TM, Dalhaimer P. Lipid Droplets: Formation to Breakdown. Lipids 2017; 52:465-475. [PMID: 28528432 DOI: 10.1007/s11745-017-4263-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 05/08/2017] [Indexed: 10/19/2022]
Abstract
One of the most exciting areas of cell biology during the last decade has been the study of lipid droplets. Lipid droplets allow cells to store non-polar molecules such as neutral lipids in specific compartments where they are sequestered from the aqueous environment of the cell yet can be accessed through regulated mechanisms. These structures are highly conserved, appearing in organisms throughout the phylogenetic tree. Until somewhat recently, lipid droplets were widely regarded as inert, however progress in the field has continued to demonstrate their vast roles in a number of cellular processes in both mitotic and post-mitotic cells. No doubt the increase in the attention given to lipid droplet research is due to their central role in current pressing human diseases such as obesity, type-2 diabetes, and atherosclerosis. This review provides a mechanistic timeline from neutral lipid synthesis through lipid droplet formation and size augmentation to droplet breakdown.
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Affiliation(s)
- Alex Meyers
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 426 Dougherty Engineering Building, Knoxville, TN, 37996, USA
| | - Taylor M Weiskittel
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 426 Dougherty Engineering Building, Knoxville, TN, 37996, USA
| | - Paul Dalhaimer
- Department of Chemical and Biomolecular Engineering, University of Tennessee, 426 Dougherty Engineering Building, Knoxville, TN, 37996, USA. .,Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA.
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20
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Adipose tissue development and the molecular regulation of lipid metabolism. Essays Biochem 2016; 60:437-450. [DOI: 10.1042/ebc20160042] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 10/18/2016] [Accepted: 10/24/2016] [Indexed: 12/14/2022]
Abstract
The production of new adipocytes is required to maintain adipose tissue mass and involves the proliferation and differentiation of adipocyte precursor cells (APCs). In this review, we outline new developments in understanding the phenotype of APCs and provide evidence suggesting that APCs differ between distinct adipose tissue depots and are affected by obesity. Post-mitotic mature adipocytes regulate systemic lipid homeostasis by storing and releasing free fatty acids, and also modulate energy balance via the secretion of adipokines. The review highlights recent advances in understanding the cellular and molecular mechanisms regulating adipocyte metabolism, with a particular focus on lipolysis regulation and the involvement of microribonucleic acids (miRNAs).
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21
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Sun C, Jiang L, Liu Y, Shen H, Weiss SJ, Zhou Y, Rui L. Adipose Snail1 Regulates Lipolysis and Lipid Partitioning by Suppressing Adipose Triacylglycerol Lipase Expression. Cell Rep 2016; 17:2015-2027. [PMID: 27851965 PMCID: PMC5131732 DOI: 10.1016/j.celrep.2016.10.070] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/25/2016] [Accepted: 10/19/2016] [Indexed: 12/14/2022] Open
Abstract
Lipolysis provides metabolic fuel; however, aberrant adipose lipolysis results in ectopic lipid accumulation and lipotoxicity. While adipose triacylglycerol lipase (ATGL) catalyzes the first step of lipolysis, its regulation is not fully understood. Here, we demonstrate that adipocyte Snail1 suppresses both ATGL expression and lipolysis. Adipose Snail1 levels are higher in fed mice than in fasted mice and higher in obese mice as opposed to lean mice. Insulin increases Snail1 levels in both murine and human adipocytes, wherein Snail1 binds to the ATGL promoter to repress its expression. Importantly, adipocyte-specific deletion of Snail1 increases adipose ATGL expression and lipolysis, resulting in decreased fat mass and increased liver fat content in mice fed either a normal chow diet or a high-fat diet. Thus, we have identified a Snail1-ATGL axis that regulates adipose lipolysis and fatty acid release, thereby governing lipid partitioning between adipose and non-adipose tissues.
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MESH Headings
- 3T3-L1 Cells
- Adipocytes, White/drug effects
- Adipocytes, White/metabolism
- Adipocytes, White/pathology
- Adipose Tissue, White/drug effects
- Adipose Tissue, White/metabolism
- Animals
- Cell Size/drug effects
- Diet, High-Fat
- Down-Regulation/drug effects
- Down-Regulation/genetics
- Epigenesis, Genetic/drug effects
- Fatty Liver/metabolism
- Fatty Liver/pathology
- Gene Deletion
- Humans
- Insulin/pharmacology
- Lipase/genetics
- Lipase/metabolism
- Lipolysis/drug effects
- Liver/drug effects
- Liver/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Obesity/metabolism
- Obesity/pathology
- Organ Specificity
- Promoter Regions, Genetic/genetics
- Snail Family Transcription Factors/metabolism
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Affiliation(s)
- Chengxin Sun
- School of Life Sciences, University of Northeast Normal University, Changchun 130024, China; Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Lin Jiang
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Yan Liu
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Hong Shen
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Stephen J Weiss
- Life Sciences Institute, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Yifa Zhou
- School of Life Sciences, University of Northeast Normal University, Changchun 130024, China.
| | - Liangyou Rui
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
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22
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Sun J, Ji H, Li XX, Shi XC, Du ZY, Chen LQ. Lipolytic enzymes involving lipolysis in Teleost: Synteny, structure, tissue distribution, and expression in grass carp (Ctenopharyngodon idella). Comp Biochem Physiol B Biochem Mol Biol 2016; 198:110-8. [DOI: 10.1016/j.cbpb.2016.04.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 04/25/2016] [Accepted: 04/25/2016] [Indexed: 02/06/2023]
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23
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Sun Q, Yue Y, Shen P, Yang JJ, Park Y. Cranberry Product Decreases Fat Accumulation in Caenorhabditis elegans. J Med Food 2016; 19:427-33. [PMID: 26991055 DOI: 10.1089/jmf.2015.0133] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cranberry phenolic compounds have been linked to many health benefits. A recent report suggested that cranberry bioactives inhibit adipogenesis in 3T3-L1 adipocytes. Thus, we investigated the effects and mechanisms of the cranberry product (CP) on lipid metabolism using the Caenorhabditis elegans (C. elegans) model. CP (0.016% and 0.08%) dose-dependently reduced overall fat accumulation in C. elegans (N2, wild type) by 43% and 74%, respectively, without affecting its pumping rates or locomotive activities. CP decreased fat accumulation in aak-2 (an ortholog of AMP-activated kinase α) and tub-1 (an ortholog of TUBBY) mutants significantly, but only minimal effects were observed in sbp-1 (an ortholog of sterol response element-binding protein-1) and nhr-49 (an ortholog of peroxisome proliferator-activated receptor-α) mutant strains. We further confirmed that CP downregulated sbp-1, cebp, and hosl-1 (an ortholog of hormone-sensitive lipase homolog) expression, while increasing the expression of nhr-49 in wild-type C. elegans. These results suggest that CP could effectively reduce fat accumulation in C. elegans dependent on sbp-1, cebp, and nhr-49, but not aak-2 and tub-1.
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Affiliation(s)
- Quancai Sun
- 1 Department of Food Science, University of Massachusetts , Amherst, Massachusetts, USA
| | - Yiren Yue
- 1 Department of Food Science, University of Massachusetts , Amherst, Massachusetts, USA
| | - Peiyi Shen
- 1 Department of Food Science, University of Massachusetts , Amherst, Massachusetts, USA
| | - Jeremy J Yang
- 2 Amherst Regional High School , Amherst, Massachusetts, USA
| | - Yeonhwa Park
- 1 Department of Food Science, University of Massachusetts , Amherst, Massachusetts, USA
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24
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Heier C, Haemmerle G. Fat in the heart: The enzymatic machinery regulating cardiac triacylglycerol metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1500-12. [PMID: 26924251 DOI: 10.1016/j.bbalip.2016.02.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 02/17/2016] [Accepted: 02/19/2016] [Indexed: 01/22/2023]
Abstract
The heart predominantly utilizes fatty acids (FAs) as energy substrate. FAs that enter cardiomyocytes can be activated and directly oxidized within mitochondria (and peroxisomes) or they can be esterified and intracellularly deposited as triacylglycerol (TAG) often simply referred to as fat. An increase in cardiac TAG can be a signature of the diseased heart and may implicate a minor role of TAG synthesis and breakdown in normal cardiac energy metabolism. Often overlooked, the heart has an extremely high TAG turnover and the transient deposition of FAs within the cardiac TAG pool critically determines the availability of FAs as energy substrate and signaling molecules. We herein review the recent literature regarding the enzymes and co-regulators involved in cardiomyocyte TAG synthesis and catabolism and discuss the interconnection of these metabolic pathways in the normal and diseased heart. This article is part of a Special Issue entitled: Heart Lipid Metabolism edited by G.D. Lopaschuk.
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Affiliation(s)
- Christoph Heier
- Institute of Molecular Biosciences, University of Graz, Austria
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25
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Kory N, Thiam AR, Farese RV, Walther TC. Protein Crowding Is a Determinant of Lipid Droplet Protein Composition. Dev Cell 2015; 34:351-63. [PMID: 26212136 PMCID: PMC4536137 DOI: 10.1016/j.devcel.2015.06.007] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 04/21/2015] [Accepted: 06/08/2015] [Indexed: 01/09/2023]
Abstract
Lipid droplets (LDs) are lipid storage organelles that grow or shrink, depending on the availability of metabolic energy. Proteins recruited to LDs mediate many metabolic functions, including phosphatidylcholine and triglyceride synthesis. How the LD protein composition is tuned to the supply and demand for lipids remains unclear. We show that LDs, in contrast to other organelles, have limited capacity for protein binding. Consequently, macromolecular crowding plays a major role in determining LD protein composition. During lipolysis, when LDs and their surfaces shrink, some, but not all, proteins become displaced. In vitro studies show that macromolecular crowding, rather than changes in monolayer lipid composition, causes proteins to fall off the LD surface. As predicted by a crowding model, proteins compete for binding to the surfaces of LDs. Moreover, the LD binding affinity determines protein localization during lipolysis. Our findings identify protein crowding as an important principle in determining LD protein composition.
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Affiliation(s)
- Nora Kory
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA
| | - Abdou-Rachid Thiam
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA; Laboratoire de Physique Statistique, École Normale Supérieure de Paris, Université Pierre et Marie Curie, Université Paris Diderot, Centre National de la Recherche Scientifique, 24 Rue Lhomond, 75005 Paris, France
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Yale School of Medicine, New Haven, CT 06510, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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Tsiloulis T, Watt MJ. Exercise and the Regulation of Adipose Tissue Metabolism. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 135:175-201. [PMID: 26477915 DOI: 10.1016/bs.pmbts.2015.06.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Adipose tissue is a major regulator of metabolism in health and disease. The prominent roles of adipose tissue are to sequester fatty acids in times of energy excess and to release fatty acids via the process of lipolysis during times of high-energy demand, such as exercise. The fatty acids released during lipolysis are utilized by skeletal muscle to produce adenosine triphosphate to prevent fatigue during prolonged exercise. Lipolysis is controlled by a complex interplay between neuro-humoral regulators, intracellular signaling networks, phosphorylation events involving protein kinase A, translocation of proteins within the cell, and protein-protein interactions. Herein, we describe in detail the cellular and molecular regulation of lipolysis and how these processes are altered by acute exercise. We also explore the processes that underpin adipocyte adaptation to endurance exercise training, with particular focus on epigenetic modifications, control by microRNAs and mitochondrial adaptations. Finally, we examine recent literature describing how exercise might influence the conversion of traditional white adipose tissue to high energy-consuming "brown-like" adipocytes and the implications that this has on whole-body energy balance.
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Affiliation(s)
- Thomas Tsiloulis
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia
| | - Matthew J Watt
- Biology of Lipid Metabolism Laboratory, Department of Physiology, Monash University, Clayton, Victoria, Australia.
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D'Andrea S. Lipid droplet mobilization: The different ways to loosen the purse strings. Biochimie 2015; 120:17-27. [PMID: 26187474 DOI: 10.1016/j.biochi.2015.07.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/11/2015] [Indexed: 01/25/2023]
Abstract
Cytosolic lipid droplets are dynamic lipid-storage organelles that play a crucial role as reservoirs of metabolic energy and membrane precursors. These organelles are present in virtually all cell types, from unicellular to pluricellular organisms. Despite similar structural organization, lipid droplets are heterogeneous in morphology, distribution and composition. The protein repertoire associated to lipid droplet controls the organelle dynamics. Distinct structural lipid droplet proteins are associated to specific lipolytic pathways. The role of these structural lipid droplet-associated proteins in the control of lipid droplet degradation and lipid store mobilization is discussed. The control of the strictly-regulated lipolysis in lipid-storing tissues is compared between mammals and plants. Differences in the cellular regulation of lipolysis between lipid-storing tissues and other cell types are also discussed.
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Affiliation(s)
- Sabine D'Andrea
- INRA, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, F-78026 Versailles, France; AgroParisTech, Institut Jean-Pierre Bourgin, UMR 1318, ERL CNRS 3559, Saclay Plant Sciences, RD10, F-78026 Versailles, France.
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