351
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Jung SM, Sanchez-Gurmaches J, Guertin DA. Brown Adipose Tissue Development and Metabolism. Handb Exp Pharmacol 2019; 251:3-36. [PMID: 30203328 DOI: 10.1007/164_2018_168] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Brown adipose tissue is well known to be a thermoregulatory organ particularly important in small rodents and human infants, but it was only recently that its existence and significance to metabolic fitness in adult humans have been widely realized. The ability of active brown fat to expend high amounts of energy has raised interest in stimulating thermogenesis therapeutically to treat metabolic diseases related to obesity and type 2 diabetes. In parallel, there has been a surge of research aimed at understanding the biology of rodent and human brown fat development, its remarkable metabolic properties, and the phenomenon of white fat browning, in which white adipocytes can be converted into brown like adipocytes with similar thermogenic properties. Here, we review the current understanding of the developmental and metabolic pathways involved in forming thermogenic adipocytes, and highlight some of the many unknown functions of brown fat that make its study a rich and exciting area for future research.
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Affiliation(s)
- Su Myung Jung
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA
| | - Joan Sanchez-Gurmaches
- Division of Endocrinology, Division of Developmental Biology, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH, USA. .,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
| | - David A Guertin
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA. .,Molecular, Cell and Cancer Biology Program, University of Massachusetts Medical School, Worcester, MA, USA. .,Lei Weibo Institute for Rare Diseases, University of Massachusetts Medical School, Worcester, MA, USA.
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352
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van Rijn JM, van Hoesel M, de Heus C, van Vugt AHM, Klumperman J, Nieuwenhuis EES, Houwen RHJ, Middendorp S. DGAT2 partially compensates for lipid-induced ER stress in human DGAT1-deficient intestinal stem cells. J Lipid Res 2019; 60:1787-1800. [PMID: 31315900 DOI: 10.1194/jlr.m094201] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/17/2019] [Indexed: 12/16/2022] Open
Abstract
Dietary lipids are taken up as FAs by the intestinal epithelium and converted by diacylglycerol acyltransferase (DGAT) enzymes into triglycerides, which are packaged in chylomicrons or stored in cytoplasmic lipid droplets (LDs). DGAT1-deficient patients suffer from vomiting, diarrhea, and protein losing enteropathy, illustrating the importance of this process to intestinal homeostasis. Previously, we have shown that DGAT1 deficiency causes decreased LD formation and resistance to unsaturated FA lipotoxicity in patient-derived intestinal organoids. However, LD formation was not completely abolished in patient-derived organoids, suggesting the presence of an alternative mechanism for LD formation. Here, we show an unexpected role for DGAT2 in lipid metabolism, as DGAT2 partially compensates for LD formation and lipotoxicity in DGAT1-deficient intestinal stem cells. Furthermore, we show that (un)saturated FA-induced lipotoxicity is mediated by ER stress. More importantly, we demonstrate that overexpression of DGAT2 fully compensates for the loss of DGAT1 in organoids, indicating that induced DGAT2 expression in patient cells may serve as a therapeutic target in the future.
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Affiliation(s)
- Jorik M van Rijn
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.,Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Marliek van Hoesel
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.,Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Cecilia de Heus
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Anke H M van Vugt
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.,Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Judith Klumperman
- Department of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Edward E S Nieuwenhuis
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Roderick H J Houwen
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Sabine Middendorp
- Division of Pediatrics, Department of Pediatric Gastroenterology, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands .,Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
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353
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VandeKopple MJ, Wu J, Auer EN, Giaccia AJ, Denko NC, Papandreou I. HILPDA Regulates Lipid Metabolism, Lipid Droplet Abundance, and Response to Microenvironmental Stress in Solid Tumors. Mol Cancer Res 2019; 17:2089-2101. [PMID: 31308147 DOI: 10.1158/1541-7786.mcr-18-1343] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/24/2019] [Accepted: 07/10/2019] [Indexed: 01/05/2023]
Abstract
Accumulation of lipid droplets has been observed in an increasing range of tumors. However, the molecular determinants of this phenotype and the impact of the tumor microenvironment on lipid droplet dynamics are not well defined. The hypoxia-inducible and lipid droplet associated protein HILPDA is known to regulate lipid storage and physiologic responses to feeding conditions in mice, and was recently shown to promote hypoxic lipid droplet formation through inhibition of the rate-limiting lipase adipose triglyceride lipase (ATGL). Here, we identify fatty acid loading and nutrient deprivation-induced autophagy as stimuli of HILPDA-dependent lipid droplet growth. Using mouse embryonic fibroblasts and human tumor cells, we found that genetic ablation of HILPDA compromised hypoxia-fatty acid- and starvation-induced lipid droplet formation and triglyceride storage. Nutrient deprivation upregulated HILPDA protein posttranscriptionally by a mechanism requiring autophagic flux and lipid droplet turnover, independent of HIF1 transactivation. Mechanistically, loss of HILPDA led to elevated lipolysis, which could be corrected by inhibition of ATGL. Lipidomic analysis revealed not only quantitative but also qualitative differences in the glycerolipid and phospholipid profile of HILPDA wild-type and knockout cells, indicating additional HILPDA functions affecting lipid metabolism. Deletion studies of HILPDA mutants identified the N-terminal hydrophobic domain as sufficient for targeting to lipid droplets and restoration of triglyceride storage. In vivo, HILPDA-ablated cells showed decreased intratumoral triglyceride levels and impaired xenograft tumor growth associated with elevated levels of apoptosis. IMPLICATIONS: Tumor microenvironmental stresses induce changes in lipid droplet dynamics via HILPDA. Regulation of triglyceride hydrolysis is crucial for cell homeostasis and tumor growth.
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Affiliation(s)
- Matthew J VandeKopple
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio
| | - Jinghai Wu
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio
| | - Erich N Auer
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio
| | - Amato J Giaccia
- Department of Radiation Oncology, Stanford University, Stanford, California
| | - Nicholas C Denko
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio
| | - Ioanna Papandreou
- Department of Radiation Oncology, The Ohio State University Comprehensive Cancer Center, Columbus, Ohio.
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354
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Abstract
Lipid droplets (LDs), important organelles for energy storage and involved in the development of metabolic disorders, are extremely dynamic and interact with many other cellular compartments to orchestrate lipid metabolism. Little is known about how these organelle contacts are changed according to cellular needs and functions under different metabolic and pathological conditions and which proteins regulate this. Here, we summarize recent exciting discoveries about the reorganization of organelle contacts in steatotic liver, including the identification of novel LD contact site proteins in cell lines and in animals. We also discuss state of the art proteomics workflows that enable the characterization of LD-organelle contacts and tethering proteins and give an outlook how this can inform obesity research.
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Affiliation(s)
- Natalie Krahmer
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, Munich-Neuherberg, Germany.,Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany.,Faculty of Health Sciences, NNF Center for Protein Research, University of Copenhagen, Denmark
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355
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Abstract
Lipid droplets (LDs) are key sites of neutral lipid storage that can be found in all cells. Metabolic imbalances between the synthesis and degradation of LDs can result in the accumulation of significant amounts of lipid deposition, a characteristic feature of hepatocytes in patients with fatty liver disease, a leading indication for liver transplant in the United States. In this review, the authors highlight new literature related to the synthesis and autophagic catabolism of LDs, discussing key proteins and machinery involved in these processes. They also discuss recent findings that have revealed novel genetic risk factors associated with LD biology that contribute to lipid retention in the diseased liver.
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Affiliation(s)
- Ryan J. Schulze
- Department of Biochemistry and Molecular Biology and the Center for Digestive Diseases, Mayo Clinic, Rochester, Minnesota
| | - Mark A. McNiven
- Department of Biochemistry and Molecular Biology and the Center for Digestive Diseases, Mayo Clinic, Rochester, Minnesota
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356
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Fan J, Yu L, Xu C. Dual Role for Autophagy in Lipid Metabolism in Arabidopsis. THE PLANT CELL 2019; 31:1598-1613. [PMID: 31036588 PMCID: PMC6635848 DOI: 10.1105/tpc.19.00170] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 03/26/2019] [Accepted: 04/19/2019] [Indexed: 05/18/2023]
Abstract
Autophagy is a major catabolic pathway whereby cytoplasmic constituents including lipid droplets (LDs), storage compartments for neutral lipids, are delivered to the lysosome or vacuole for degradation. The autophagic degradation of cytosolic LDs, a process termed lipophagy, has been extensively studied in yeast and mammals, but little is known about the role for autophagy in lipid metabolism in plants. Organisms maintain a basal level of autophagy under favorable conditions and upregulate the autophagic activity under stress including starvation. Here, we demonstrate that Arabidopsis (Arabidopsis thaliana) basal autophagy contributes to triacylglycerol (TAG) synthesis, whereas inducible autophagy contributes to LD degradation. We found that disruption of basal autophagy impedes organellar membrane lipid turnover and hence fatty acid mobilization from membrane lipids to TAG. We show that lipophagy is induced under starvation as indicated by colocalization of LDs with the autophagic marker and the presence of LDs in vacuoles. We additionally show that lipophagy occurs in a process morphologically resembling microlipophagy and requires the core components of the macroautophagic machinery. Together, this study provides mechanistic insight into lipophagy and reveals a dual role for autophagy in regulating lipid synthesis and turnover in plants.
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Affiliation(s)
- Jilian Fan
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973
| | - Linhui Yu
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973
| | - Changcheng Xu
- Biology Department, Brookhaven National Laboratory, Upton, New York 11973
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357
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Chang CL, Weigel AV, Ioannou MS, Pasolli HA, Xu CS, Peale DR, Shtengel G, Freeman M, Hess HF, Blackstone C, Lippincott-Schwartz J. Spastin tethers lipid droplets to peroxisomes and directs fatty acid trafficking through ESCRT-III. J Cell Biol 2019; 218:2583-2599. [PMID: 31227594 PMCID: PMC6683741 DOI: 10.1083/jcb.201902061] [Citation(s) in RCA: 149] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/29/2019] [Accepted: 05/28/2019] [Indexed: 12/22/2022] Open
Abstract
Lipid droplets (LDs) are neutral lipid storage organelles that transfer lipids to various organelles including peroxisomes. Here, we show that the hereditary spastic paraplegia protein M1 Spastin, a membrane-bound AAA ATPase found on LDs, coordinates fatty acid (FA) trafficking from LDs to peroxisomes through two interrelated mechanisms. First, M1 Spastin forms a tethering complex with peroxisomal ABCD1 to promote LD-peroxisome contact formation. Second, M1 Spastin recruits the membrane-shaping ESCRT-III proteins IST1 and CHMP1B to LDs via its MIT domain to facilitate LD-to-peroxisome FA trafficking, possibly through IST1- and CHMP1B-dependent modifications in LD membrane morphology. Furthermore, LD-to-peroxisome FA trafficking mediated by M1 Spastin is required to relieve LDs of lipid peroxidation. M1 Spastin's dual roles in tethering LDs to peroxisomes and in recruiting ESCRT-III components to LD-peroxisome contact sites for FA trafficking may underlie the pathogenesis of diseases associated with defective FA metabolism in LDs and peroxisomes.
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Affiliation(s)
- Chi-Lun Chang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Aubrey V Weigel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Maria S Ioannou
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - H Amalia Pasolli
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - C Shan Xu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - David R Peale
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Gleb Shtengel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Melanie Freeman
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Harald F Hess
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Craig Blackstone
- Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD
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358
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Abstract
Significance: In addition to their classical role in cellular ATP production, mitochondria are of key relevance in various (patho)physiological mechanisms including second messenger signaling, neuro-transduction, immune responses and death induction. Recent Advances: Within cells, mitochondria are motile and display temporal changes in internal and external structure ("mitochondrial dynamics"). During the last decade, substantial empirical and in silico evidence was presented demonstrating that mitochondrial dynamics impacts on mitochondrial function and vice versa. Critical Issues: However, a comprehensive and quantitative understanding of the bidirectional links between mitochondrial external shape, internal structure and function ("morphofunction") is still lacking. The latter particularly hampers our understanding of the functional properties and behavior of individual mitochondrial within single living cells. Future Directions: In this review we discuss the concept of mitochondrial morphofunction in mammalian cells, primarily using experimental evidence obtained within the last decade. The topic is introduced by briefly presenting the central role of mitochondria in cell physiology and the importance of the mitochondrial electron transport chain (ETC) therein. Next, we summarize in detail how mitochondrial (ultra)structure is controlled and discuss empirical evidence regarding the equivalence of mitochondrial (ultra)structure and function. Finally, we provide a brief summary of how mitochondrial morphofunction can be quantified at the level of single cells and mitochondria, how mitochondrial ultrastructure/volume impacts on mitochondrial bioreactions and intramitochondrial protein diffusion, and how mitochondrial morphofunction can be targeted by small molecules.
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Affiliation(s)
- Elianne P. Bulthuis
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Merel J.W. Adjobo-Hermans
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Peter H.G.M. Willems
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Werner J.H. Koopman
- Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands
- Address correspondence to: Dr. Werner J.H. Koopman, Department of Biochemistry (286), Radboud Institute for Molecular Life Sciences, Radboud University Medical Centre, P.O. Box 9101, Nijmegen NL-6500 HB, The Netherlands
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359
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Krois CR, Vuckovic MG, Huang P, Zaversnik C, Liu CS, Gibson CE, Wheeler MR, Obrochta KM, Min JH, Herber CB, Thompson AC, Shah ID, Gordon SP, Hellerstein MK, Napoli JL. RDH1 suppresses adiposity by promoting brown adipose adaptation to fasting and re-feeding. Cell Mol Life Sci 2019; 76:2425-2447. [PMID: 30788515 PMCID: PMC6531335 DOI: 10.1007/s00018-019-03046-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 02/07/2019] [Accepted: 02/11/2019] [Indexed: 12/26/2022]
Abstract
RDH1 is one of the several enzymes that catalyze the first of the two reactions to convert retinol into all-trans-retinoic acid (atRA). Here, we show that Rdh1-null mice fed a low-fat diet gain more weight as adiposity (17% males, 13% females) than wild-type mice by 20 weeks old, despite neither consuming more calories nor decreasing activity. Glucose intolerance and insulin resistance develop following increased adiposity. Despite the increase in white fat pads, epididymal white adipose does not express Rdh1, nor does muscle. Brown adipose tissue (BAT) and liver express Rdh1 at relatively high levels compared to other tissues. Rdh1 ablation lowered body temperatures during ambient conditions. Given the decreased body temperature, we focused on BAT. A lack of differences in BAT adipogenic gene expression between Rdh1-null mice and wild-type mice, including Pparg, Prdm16, Zfp516 and Zfp521, indicated that the phenotype was not driven by brown adipose hyperplasia. Rather, Rdh1 ablation eliminated the increase in BAT atRA that occurs after re-feeding. This disruption of atRA homeostasis increased fatty acid uptake, but attenuated lipolysis in primary brown adipocytes, resulting in increased lipid content and larger lipid droplets. Rdh1 ablation also decreased mitochondrial proteins, including CYCS and UCP1, the mitochondria oxygen consumption rate, and disrupted the mitochondria membrane potential, further reflecting impaired BAT function, resulting in both BAT and white adipose hypertrophy. RNAseq revealed dysregulation of 424 BAT genes in null mice, which segregated predominantly into differences after fasting vs after re-feeding. Exceptions were Rbp4 and Gbp2b, which increased during both dietary conditions. Rbp4 encodes the serum retinol-binding protein-an insulin desensitizer. Gbp2b encodes a GTPase. Because Gbp2b increased several hundred-fold, we overexpressed it in brown adipocytes. This caused a shift to larger lipid droplets, suggesting that GBP2b affects signaling downstream of the β-adrenergic receptor during basal thermogenesis. Thus, Rdh1-generated atRA in BAT regulates multiple genes that promote BAT adaptation to whole-body energy status, such as fasting and re-feeding. These gene expression changes promote optimum mitochondria function and thermogenesis, limiting adiposity. Attenuation of adiposity and insulin resistance suggests that RDH1 mitigates metabolic syndrome.
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Affiliation(s)
- Charles R Krois
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Department of Chemistry and Geology, Minnesota State University, 241 Ford Hall, Mankato, MN, 56001, USA
| | - Marta G Vuckovic
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
| | - Priscilla Huang
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Arizona College of Osteopathic Medicine, Midwestern University, 19555 North 59th Avenue, Glendale, AZ, 85308, USA
| | - Claire Zaversnik
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- AgroSup Dijon, 26 Bd Petitjean, 21000, Dijon, France
| | - Conan S Liu
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Sidney Kimmel Medical College, 1025 Walnut Street, Philadelphia, PA, 19104, USA
| | - Candice E Gibson
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
| | - Madelyn R Wheeler
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- UC Davis School of Medicine, 4102 Sherman Way, Sacramento, CA, 95817, USA
| | - Kristin M Obrochta
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Biomarin Pharmaceutical Inc., 105 Digital Drive, Novato, CA, 94949, USA
| | - Jin H Min
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Nova Southeastern University, 3301 College Avenue, Fort Lauderdale, FL, 33314, USA
| | - Candice B Herber
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- University of California, San Francisco, Rock Hall 281, 1550 4th Street, San Francisco, CA, 94158, USA
| | - Airlia C Thompson
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Stanford University, Lorry Lokey Building Room 164, 337 Campus Drive, Stanford, CA, 94305-5020, USA
| | - Ishan D Shah
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
- Keck School of Medicine, University of Southern California, 1975 Zonal Avenue, Keith Administration (KAM) 100, Los Angeles, CA, 90089-9020, USA
| | - Sean P Gordon
- DOE Joint Genome Institute, 2800 Mitchell Dr # 100, Walnut Creek, CA, 94598, USA
| | - Marc K Hellerstein
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA
| | - Joseph L Napoli
- Graduate Program in Metabolic Biology, Department of Nutritional Sciences and Toxicology, University of California, Berkeley, 119 Morgan Hall, Berkeley, CA, 94720-3104, USA.
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360
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Ioannou MS, Jackson J, Sheu SH, Chang CL, Weigel AV, Liu H, Pasolli HA, Xu CS, Pang S, Matthies D, Hess HF, Lippincott-Schwartz J, Liu Z. Neuron-Astrocyte Metabolic Coupling Protects against Activity-Induced Fatty Acid Toxicity. Cell 2019; 177:1522-1535.e14. [PMID: 31130380 DOI: 10.1016/j.cell.2019.04.001] [Citation(s) in RCA: 433] [Impact Index Per Article: 72.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 02/20/2019] [Accepted: 03/28/2019] [Indexed: 01/08/2023]
Abstract
Metabolic coordination between neurons and astrocytes is critical for the health of the brain. However, neuron-astrocyte coupling of lipid metabolism, particularly in response to neural activity, remains largely uncharacterized. Here, we demonstrate that toxic fatty acids (FAs) produced in hyperactive neurons are transferred to astrocytic lipid droplets by ApoE-positive lipid particles. Astrocytes consume the FAs stored in lipid droplets via mitochondrial β-oxidation in response to neuronal activity and turn on a detoxification gene expression program. Our findings reveal that FA metabolism is coupled in neurons and astrocytes to protect neurons from FA toxicity during periods of enhanced activity. This coordinated mechanism for metabolizing FAs could underlie both homeostasis and a variety of disease states of the brain.
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Affiliation(s)
- Maria S Ioannou
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
| | - Jesse Jackson
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada; Neuroscience and Mental Health Institute, Edmonton, AB T6G 2E1, Canada
| | - Shu-Hsien Sheu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Chi-Lun Chang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Aubrey V Weigel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Hui Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - H Amalia Pasolli
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - C Shan Xu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Song Pang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Doreen Matthies
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Harald F Hess
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | | | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
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361
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Fantin M, Garelli F, Napoli B, Forgiarini A, Gumeni S, De Martin S, Montopoli M, Vantaggiato C, Orso G. Flavonoids Regulate Lipid Droplets Biogenesis in Drosophila melanogaster. Nat Prod Commun 2019. [DOI: 10.1177/1934578x19852430] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Lipid droplets (LDs), cytosolic fat storage organelles, are emerging as major regulators of lipid metabolism, trafficking, and signaling in various cells and tissues. LDs are altered in cardiovascular and neuronal disorders, inflammation, obesity, and cancer. Flavonoids comprise different classes of molecules, characterized by a well-known antioxidant activity and a beneficial effect in several diseases. However, the cellular mechanism by which different classes of flavonoids improve health is poorly understood, in particular as far as LDs biogenesis is concerned. Here we used Drosophila melanogaster as a model system to investigate the effects of a selected group of flavonoids on larval tissues by examining LDs biogenesis. In our study, fruit flies were grown in xanthohumol-, isoquercetin-, and genistein-enriched food and larval tissues were analyzed using a LD marker. Total mRNA expression of two main enzymes (minotaur and midway) responsible for triacylglycerides synthesis was evaluated after treatments. Among the flavonoids analyzed, xanthohumol and isoquercetin resulted to be potent regulators of LDs biogenesis in a tissue-specific manner, inducing fat storage decrease in fat bodies and accumulation of LDs in nerves. Since LDs have been suggested to play a protective role against intracellular stress in nonadipocyte cells, our data support the hypothesis that some phytochemicals could act as strong modulators of LDs biogenesis in vivo. The knowledge of how different flavonoids act on lipid metabolism in different tissues can help to manage the use of phytochemicals with the aim of selectively ameliorating specific neuronal and metabolic diseases’ manifestations.
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Affiliation(s)
- Marianna Fantin
- Scientific Institute, IRCCS E. Medea, Laboratory of Molecular Biology, Bosisio Parini, Lecco, Italy
| | - Francesca Garelli
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Italy
| | - Barbara Napoli
- Scientific Institute, IRCCS E. Medea, Laboratory of Molecular Biology, Bosisio Parini, Lecco, Italy
| | - Alessia Forgiarini
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Italy
| | - Sentiljana Gumeni
- Department of Cell Biology and Biophysics, Faculty of Biology, National and Kapodistrian University of Athens, Greece
| | - Sara De Martin
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Italy
| | - Monica Montopoli
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Italy
| | - Chiara Vantaggiato
- Scientific Institute, IRCCS E. Medea, Laboratory of Molecular Biology, Bosisio Parini, Lecco, Italy
| | - Genny Orso
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Italy
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362
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Wang X, Wang QC, Sun Z, Li T, Yang K, An C, Guo C, Tang TS. ER stress mediated degradation of diacylglycerol acyltransferase impairs mitochondrial functions in TMCO1 deficient cells. Biochem Biophys Res Commun 2019; 512:914-920. [DOI: 10.1016/j.bbrc.2019.03.115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 03/18/2019] [Indexed: 12/17/2022]
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363
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Benador IY, Veliova M, Liesa M, Shirihai OS. Mitochondria Bound to Lipid Droplets: Where Mitochondrial Dynamics Regulate Lipid Storage and Utilization. Cell Metab 2019; 29:827-835. [PMID: 30905670 PMCID: PMC6476311 DOI: 10.1016/j.cmet.2019.02.011] [Citation(s) in RCA: 207] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 01/21/2019] [Accepted: 02/21/2019] [Indexed: 01/09/2023]
Abstract
The isolation and biochemical characterization of lipid droplet (LD)-associated mitochondria revealed the capacity of the cell to produce and maintain distinct mitochondrial populations carrying disparate proteome and dissimilar capacities to oxidize fatty acids and pyruvate. With mitochondrial motility being a central parameter determining mitochondrial fusion, adherence to LDs provides a mechanism by which peridroplet mitochondria (PDM) remain segregated from cytoplasmic mitochondria (CM). The existence of metabolically distinct subpopulations provides an explanation for the capacity of mitochondria within the individual cell to be involved simultaneously in fatty acid oxidation and LD formation. The mechanisms that deploy mitochondria to the LD and the dysfunctions that result from unbalanced proportions of PDM and CM remain to be explored. Understanding the roles and regulation of mitochondrial tethering to LDs offers new points of intervention in metabolic diseases.
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Affiliation(s)
- Ilan Y Benador
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Michaela Veliova
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Marc Liesa
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; UCLA Molecular Biology Institute, Los Angeles, CA, USA.
| | - Orian S Shirihai
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA, USA.
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364
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Imai Y, Cousins RS, Liu S, Phelps BM, Promes JA. Connecting pancreatic islet lipid metabolism with insulin secretion and the development of type 2 diabetes. Ann N Y Acad Sci 2019; 1461:53-72. [PMID: 30937918 DOI: 10.1111/nyas.14037] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 01/24/2019] [Accepted: 01/30/2019] [Indexed: 02/06/2023]
Abstract
Obesity is the major contributing factor for the increased prevalence of type 2 diabetes (T2D) in recent years. Sustained positive influx of lipids is considered to be a precipitating factor for beta cell dysfunction and serves as a connection between obesity and T2D. Importantly, fatty acids (FA), a key building block of lipids, are a double-edged sword for beta cells. FA acutely increase glucose-stimulated insulin secretion through cell-surface receptor and intracellular pathways. However, chronic exposure to FA, combined with elevated glucose, impair the viability and function of beta cells in vitro and in animal models of obesity (glucolipotoxicity), providing an experimental basis for the propensity of beta cell demise under obesity in humans. To better understand the two-sided relationship between lipids and beta cells, we present a current view of acute and chronic handling of lipids by beta cells and implications for beta cell function and health. We also discuss an emerging role for lipid droplets (LD) in the dynamic regulation of lipid metabolism in beta cells and insulin secretion, along with a potential role for LD under nutritional stress in beta cells, and incorporate recent advancement in the field of lipid droplet biology.
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Affiliation(s)
- Yumi Imai
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa
| | - Ryan S Cousins
- Department of Internal Medicine, Eastern Virginia Medical School, Norfolk, Virginia
| | - Siming Liu
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa
| | - Brian M Phelps
- Department of Internal Medicine, Eastern Virginia Medical School, Norfolk, Virginia
| | - Joseph A Promes
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa.,Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa
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365
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Schrul B, Schliebs W. Intracellular communication between lipid droplets and peroxisomes: the Janus face of PEX19. Biol Chem 2019; 399:741-749. [PMID: 29500918 DOI: 10.1515/hsz-2018-0125] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 02/23/2018] [Indexed: 02/06/2023]
Abstract
In order to adapt to environmental changes, such as nutrient availability, cells have to orchestrate multiple metabolic pathways, which are catalyzed in distinct specialized organelles. Lipid droplets (LDs) and peroxisomes are both endoplasmic reticulum (ER)-derived organelles that fulfill complementary functions in lipid metabolism: Upon nutrient supply, LDs store metabolic energy in the form of neutral lipids and, when energy is needed, supply fatty acids for oxidation in peroxisomes and mitochondria. How these organelles communicate with each other for a concerted metabolic output remains a central question. Here, we summarize recent insights into the biogenesis and function of LDs and peroxisomes with emphasis on the role of PEX19 in these processes.
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Affiliation(s)
- Bianca Schrul
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, Kirrberger Str. 100, D-66421 Homburg/Saar, Germany
| | - Wolfgang Schliebs
- Institute of Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Faculty of Medicine, Ruhr University Bochum, D-44780 Bochum, Germany
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366
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Abstract
Lipid droplets are storage organelles at the centre of lipid and energy homeostasis. They have a unique architecture consisting of a hydrophobic core of neutral lipids, which is enclosed by a phospholipid monolayer that is decorated by a specific set of proteins. Originating from the endoplasmic reticulum, lipid droplets can associate with most other cellular organelles through membrane contact sites. It is becoming apparent that these contacts between lipid droplets and other organelles are highly dynamic and coupled to the cycles of lipid droplet expansion and shrinkage. Importantly, lipid droplet biogenesis and degradation, as well as their interactions with other organelles, are tightly coupled to cellular metabolism and are critical to buffer the levels of toxic lipid species. Thus, lipid droplets facilitate the coordination and communication between different organelles and act as vital hubs of cellular metabolism.
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Affiliation(s)
- James A Olzmann
- Department of Nutritional Sciences and Toxicology, University of California-Berkeley, Berkeley, CA, USA.
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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367
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Hariri H, Speer N, Bowerman J, Rogers S, Fu G, Reetz E, Datta S, Feathers JR, Ugrankar R, Nicastro D, Henne WM. Mdm1 maintains endoplasmic reticulum homeostasis by spatially regulating lipid droplet biogenesis. J Cell Biol 2019; 218:1319-1334. [PMID: 30808705 PMCID: PMC6446837 DOI: 10.1083/jcb.201808119] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 01/10/2019] [Accepted: 01/22/2019] [Indexed: 12/13/2022] Open
Abstract
Excess fatty acids are toxic to cells but can be sequestered as triacylglycerides in lipid droplets. Hariri et al. show that the tethering protein Mdm1 spatially regulates this process at the junction between the endoplasmic reticulum and the yeast vacuole. These findings suggest that Mdm1 can drive spatially defined lipid droplet production to maintain cell homeostasis and protect against lipotoxicity. Lipid droplets (LDs) serve as cytoplasmic reservoirs for energy-rich fatty acids (FAs) stored in the form of triacylglycerides (TAGs). During nutrient stress, yeast LDs cluster adjacent to the vacuole/lysosome, but how this LD accumulation is coordinated remains poorly understood. The ER protein Mdm1 is a molecular tether that plays a role in clustering LDs during nutrient depletion, but its mechanism of function remains unknown. Here, we show that Mdm1 associates with LDs through its hydrophobic N-terminal region, which is sufficient to demarcate sites for LD budding. Mdm1 binds FAs via its Phox-associated domain and coenriches with fatty acyl–coenzyme A ligase Faa1 at LD bud sites. Consistent with this, loss of MDM1 perturbs free FA activation and Dga1-dependent synthesis of TAGs, elevating the cellular FA level, which perturbs ER morphology and sensitizes yeast to FA-induced lipotoxicity. We propose that Mdm1 coordinates FA activation adjacent to the vacuole to promote LD production in response to stress, thus maintaining ER homeostasis.
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Affiliation(s)
- Hanaa Hariri
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Natalie Speer
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Jade Bowerman
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Sean Rogers
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Gang Fu
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Evan Reetz
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Sanchari Datta
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - J Ryan Feathers
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Rupali Ugrankar
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Daniela Nicastro
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - W Mike Henne
- Department of Cell Biology and Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
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368
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Papsdorf K, Brunet A. Linking Lipid Metabolism to Chromatin Regulation in Aging. Trends Cell Biol 2019; 29:97-116. [PMID: 30316636 PMCID: PMC6340780 DOI: 10.1016/j.tcb.2018.09.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/20/2018] [Accepted: 09/21/2018] [Indexed: 12/13/2022]
Abstract
The lifespan of an organism is strongly influenced by environmental factors (including diet) and by internal factors (notably reproductive status). Lipid metabolism is critical for adaptation to external conditions or reproduction. Interestingly, specific lipid profiles are associated with longevity, and increased uptake of certain lipids extends longevity in Caenorhabditis elegans and ameliorates disease phenotypes in humans. How lipids impact longevity, and how lipid metabolism is regulated during aging, is just beginning to be unraveled. This review describes recent advances in the regulation and role of lipids in longevity, focusing on the interaction between lipid metabolism and chromatin states in aging and age-related diseases.
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Affiliation(s)
- Katharina Papsdorf
- Department of Genetics, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA
| | - Anne Brunet
- Department of Genetics, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA; Glenn Laboratories for the Biology of Aging, Stanford University, Stanford, CA 94305, USA.
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369
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Magtanong L, Ko PJ, To M, Cao JY, Forcina GC, Tarangelo A, Ward CC, Cho K, Patti GJ, Nomura DK, Olzmann JA, Dixon SJ. Exogenous Monounsaturated Fatty Acids Promote a Ferroptosis-Resistant Cell State. Cell Chem Biol 2019; 26:420-432.e9. [PMID: 30686757 PMCID: PMC6430697 DOI: 10.1016/j.chembiol.2018.11.016] [Citation(s) in RCA: 694] [Impact Index Per Article: 115.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 09/18/2018] [Accepted: 11/27/2018] [Indexed: 01/05/2023]
Abstract
The initiation and execution of cell death can be regulated by various lipids. How the levels of environmental (exogenous) lipids impact cell death sensitivity is not well understood. We find that exogenous monounsaturated fatty acids (MUFAs) potently inhibit the non-apoptotic, iron-dependent, oxidative cell death process of ferroptosis. This protective effect is associated with the suppression of lipid reactive oxygen species (ROS) accumulation at the plasma membrane and decreased levels of phospholipids containing oxidizable polyunsaturated fatty acids. Treatment with exogenous MUFAs reduces the sensitivity of plasma membrane lipids to oxidation over several hours. This effect requires MUFA activation by acyl-coenzyme A synthetase long-chain family member 3 (ACSL3) and is independent of lipid droplet formation. Exogenous MUFAs also protect cells from apoptotic lipotoxicity caused by the accumulation of saturated fatty acids, but in an ACSL3-independent manner. Our work demonstrates that ACSL3-dependent MUFA activation promotes a ferroptosis-resistant cell state.
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Affiliation(s)
- Leslie Magtanong
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Pin-Joe Ko
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Milton To
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | | | - Amy Tarangelo
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Carl C Ward
- Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kevin Cho
- Departments of Chemistry and Medicine, Washington University, St. Louis, MO 63130, USA
| | - Gary J Patti
- Departments of Chemistry and Medicine, Washington University, St. Louis, MO 63130, USA
| | - Daniel K Nomura
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA; Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - James A Olzmann
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Scott J Dixon
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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370
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Coliva G, Duarte S, Pérez-Sala D, Fedorova M. Impact of inhibition of the autophagy-lysosomal pathway on biomolecules carbonylation and proteome regulation in rat cardiac cells. Redox Biol 2019; 23:101123. [PMID: 30737170 PMCID: PMC6859560 DOI: 10.1016/j.redox.2019.101123] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 01/21/2019] [Accepted: 01/23/2019] [Indexed: 01/13/2023] Open
Abstract
Cells employ multiple defence mechanisms to sustain a wide range of stress conditions associated with accumulation of modified self-biomolecules leading to lipo- and proteotoxicity. One of such mechanisms involves activation of the autophagy-lysosomal pathway for removal and degradation of modified lipids, proteins and even organelles. Biomolecules carbonylation, an irreversible oxidative modification, occurs in a variety of pathological conditions and is generally viewed as a marker of oxidative stress. Here, we used a model of rat primary cardiac cells to elucidate the role of autophagy-lysosomal pathway in the turnover of carbonylated biomolecules. Cells treated with inhibitors of autophagy-lysosomal degradation and primed with a short pulse of mild nitroxidative stress were studied using fluorescent microscopy and accumulation of carbonylated biomolecules in droplets- or vesicle-like structures was observed. Furthermore, systems-wide analysis of proteome regulation using relative label free quantification approach revealed the most significant alterations in cells treated with protease inhibitors. Interestingly, down-regulation of insulin signalling was among the most enriched pathway, as revealed by functional annotation of regulated proteins. Starvation induced autophagy promotes cellular carbonylation. Inhibition of autophagy-lysosomal flux leads to carbonyls accumulation. Cellular carbonyls coincide with Nile Red positive structures. Inhibition of autophagy-lysosomal flux induces proteome alterations. Impairment of autophagy-lysosomal flux results in changes in metabolic and nutrient sensing pathways.
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Affiliation(s)
- Giulia Coliva
- Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, University of Leipzig, Deutscher Platz 5, 04103 Leipzig, Germany; Center for Biotechnology and Biomedicine, University of Leipzig, Deutscher Platz 5, 04103 Leipzig, Germany
| | - Sofia Duarte
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas, C.S.I.C., 28040 Madrid, Spain
| | - Dolores Pérez-Sala
- Department of Structural and Chemical Biology, Centro de Investigaciones Biológicas, C.S.I.C., 28040 Madrid, Spain
| | - Maria Fedorova
- Institute of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, University of Leipzig, Deutscher Platz 5, 04103 Leipzig, Germany; Center for Biotechnology and Biomedicine, University of Leipzig, Deutscher Platz 5, 04103 Leipzig, Germany.
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371
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Li X, Li Y, Jiang M, Wu W, He S, Chen C, Qin Z, Tang BZ, Mak HY, Qu JY. Quantitative Imaging of Lipid Synthesis and Lipolysis Dynamics in Caenorhabditis elegans by Stimulated Raman Scattering Microscopy. Anal Chem 2019; 91:2279-2287. [PMID: 30589537 DOI: 10.1021/acs.analchem.8b04875] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Quantitative methods to precisely measure cellular states in vivo have become increasingly important and desirable in modern biology. Recently, stimulated Raman scattering (SRS) microscopy has emerged as a powerful tool to visualize small biological molecules tagged with alkyne (C≡C) or carbon-deuterium (C-D) bonds in the cell-silent region. In this study, we developed a technique based on SRS microscopy of vibrational tags for quantitative imaging of lipid synthesis and lipolysis in live animals. The technique aims to overcome the major limitations of conventional fluorescent staining and lipid extraction methods that do not provide the capability of in vivo quantitative analysis. Specifically, we used three bioorthogonal lipid molecules (the alkyne-tagged fatty acid 17-ODYA, deuterium-labeled saturated fatty acid PA-D31, and unsaturated fatty acid OA-D34) to investigate the metabolic dynamics of lipid droplets (LDs) in live Caenorhabditis elegans ( C. elegans). Using a hyperspectral SRS (hsSRS) microscope and subtraction method, the interfering non-Raman background was eliminated to improve the accuracy of lipid quantification. A linear relationship between SRS signals and fatty acid molar concentrations was accurately established. With this quantitative analysis tool, we imaged and determined the changes in concentration of the three fatty acids in LDs of fed or starved adult C. elegans. Using the hsSRS imaging mode, we also observed the desaturation of fatty acids in adult C. elegans via spectral analysis on the SRS signals from LDs. The results demonstrated the unique capability of hsSRS microscopy in quantitative analysis of lipid metabolism in vivo.
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Affiliation(s)
- Xuesong Li
- Department of Electronic and Computer Engineering , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Yan Li
- Division of Life Science , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Meijuan Jiang
- Department of Chemistry , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Wanjie Wu
- Department of Electronic and Computer Engineering , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Sicong He
- Department of Electronic and Computer Engineering , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Congping Chen
- Department of Electronic and Computer Engineering , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Zhongya Qin
- Department of Electronic and Computer Engineering , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Ben Zhong Tang
- Department of Chemistry , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Ho Yi Mak
- Division of Life Science , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
| | - Jianan Y Qu
- Department of Electronic and Computer Engineering , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China.,Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study , Hong Kong University of Science and Technology , Clear Water Bay , Kowloon , Hong Kong 999077 , China
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372
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Krahmer N, Najafi B, Schueder F, Quagliarini F, Steger M, Seitz S, Kasper R, Salinas F, Cox J, Uhlenhaut NH, Walther TC, Jungmann R, Zeigerer A, Borner GHH, Mann M. Organellar Proteomics and Phospho-Proteomics Reveal Subcellular Reorganization in Diet-Induced Hepatic Steatosis. Dev Cell 2018; 47:205-221.e7. [PMID: 30352176 DOI: 10.1016/j.devcel.2018.09.017] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/29/2018] [Accepted: 09/18/2018] [Indexed: 01/20/2023]
Abstract
Lipid metabolism is highly compartmentalized between cellular organelles that dynamically adapt their compositions and interactions in response to metabolic challenges. Here, we investigate how diet-induced hepatic lipid accumulation, observed in non-alcoholic fatty liver disease (NAFLD), affects protein localization, organelle organization, and protein phosphorylation in vivo. We develop a mass spectrometric workflow for protein and phosphopeptide correlation profiling to monitor levels and cellular distributions of ∼6,000 liver proteins and ∼16,000 phosphopeptides during development of steatosis. Several organelle contact site proteins are targeted to lipid droplets (LDs) in steatotic liver, tethering organelles orchestrating lipid metabolism. Proteins of the secretory pathway dramatically redistribute, including the mis-localization of the COPI complex and sequestration of the Golgi apparatus at LDs. This correlates with reduced hepatic protein secretion. Our systematic in vivo analysis of subcellular rearrangements and organelle-specific phosphorylation reveals how nutrient overload leads to organellar reorganization and cellular dysfunction.
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Affiliation(s)
- Natalie Krahmer
- Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Bahar Najafi
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg 85764, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, Heidelberg, Germany; German Center for Diabetes Research (DZD), Neuherberg 85764, Germany
| | - Florian Schueder
- Department of Physics and Center for Nanoscience, Ludwig Maximilian University, Munich, Germany; Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Fabiana Quagliarini
- Helmholtz Diabetes Center (HMGU) and German Center for Diabetes Research (DZD), IDO, Garching, Munich 85748, Germany
| | - Martin Steger
- Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Susanne Seitz
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg 85764, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, Heidelberg, Germany; German Center for Diabetes Research (DZD), Neuherberg 85764, Germany
| | - Robert Kasper
- Max Planck Institute of Neurobiology, Imaging facility, Martinsried 82152, Germany
| | - Favio Salinas
- Computational Systems Biochemistry, Max-Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Jürgen Cox
- Computational Systems Biochemistry, Max-Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Nina Henriette Uhlenhaut
- Helmholtz Diabetes Center (HMGU) and German Center for Diabetes Research (DZD), IDO, Garching, Munich 85748, Germany
| | - Tobias Christian Walther
- 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 Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Ralf Jungmann
- Department of Physics and Center for Nanoscience, Ludwig Maximilian University, Munich, Germany; Max Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Anja Zeigerer
- Institute for Diabetes and Cancer, Helmholtz Center Munich, Neuherberg 85764, Germany; Joint Heidelberg-IDC Translational Diabetes Program, Inner Medicine 1, Heidelberg University Hospital, Heidelberg, Germany; German Center for Diabetes Research (DZD), Neuherberg 85764, Germany
| | - Georg Heinz Helmut Borner
- Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried 82152, Germany
| | - Matthias Mann
- Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Martinsried 82152, Germany; Faculty of Health Sciences, NNF Center for Protein Research, University of Copenhagen, Copenhagen 2200, Denmark.
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373
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Hernando-Rodríguez B, Artal-Sanz M. Mitochondrial Quality Control Mechanisms and the PHB (Prohibitin) Complex. Cells 2018; 7:cells7120238. [PMID: 30501123 PMCID: PMC6315423 DOI: 10.3390/cells7120238] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 11/27/2018] [Accepted: 11/28/2018] [Indexed: 12/12/2022] Open
Abstract
Mitochondrial functions are essential for life, critical for development, maintenance of stem cells, adaptation to physiological changes, responses to stress, and aging. The complexity of mitochondrial biogenesis requires coordinated nuclear and mitochondrial gene expression, owing to the need of stoichiometrically assemble the oxidative phosphorylation (OXPHOS) system for ATP production. It requires, in addition, the import of a large number of proteins from the cytosol to keep optimal mitochondrial function and metabolism. Moreover, mitochondria require lipid supply for membrane biogenesis, while it is itself essential for the synthesis of membrane lipids. To achieve mitochondrial homeostasis, multiple mechanisms of quality control have evolved to ensure that mitochondrial function meets cell, tissue, and organismal demands. Herein, we give an overview of mitochondrial mechanisms that are activated in response to stress, including mitochondrial dynamics, mitophagy and the mitochondrial unfolded protein response (UPRmt). We then discuss the role of these stress responses in aging, with particular focus on Caenorhabditis elegans. Finally, we review observations that point to the mitochondrial prohibitin (PHB) complex as a key player in mitochondrial homeostasis, being essential for mitochondrial biogenesis and degradation, and responding to mitochondrial stress. Understanding how mitochondria responds to stress and how such responses are regulated is pivotal to combat aging and disease.
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Affiliation(s)
- Blanca Hernando-Rodríguez
- Andalusian Center for Developmental Biology, Consejo Superior de Investigaciones Científicas, Junta de Andalucía, Universidad Pablo de Olavide, 41013 Seville, Spain.
- Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, 41013 Seville, Spain.
| | - Marta Artal-Sanz
- Andalusian Center for Developmental Biology, Consejo Superior de Investigaciones Científicas, Junta de Andalucía, Universidad Pablo de Olavide, 41013 Seville, Spain.
- Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, 41013 Seville, Spain.
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374
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Dropping in on lipid droplets: insights into cellular stress and cancer. Biosci Rep 2018; 38:BSR20180764. [PMID: 30111611 PMCID: PMC6146295 DOI: 10.1042/bsr20180764] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 08/01/2018] [Accepted: 08/06/2018] [Indexed: 02/07/2023] Open
Abstract
Lipid droplets (LD) have increasingly become a major topic of research in recent years following its establishment as a highly dynamic organelle. Contrary to the initial view of LDs being passive cytoplasmic structures for lipid storage, studies have provided support on how they act in concert with different organelles to exert functions in various cellular processes. Although lipid dysregulation resulting from aberrant LD homeostasis has been well characterised, how this translates and contributes to cancer progression is poorly understood. This review summarises the different paradigms on how LDs function in the regulation of cellular stress as a contributing factor to cancer progression. Mechanisms employed by a broad range of cancer cell types in differentially utilising LDs for tumourigenesis will also be highlighted. Finally, we discuss the potential of targeting LDs in the context of cancer therapeutics.
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375
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Van Den Brink DM, Cubizolle A, Chatelain G, Davoust N, Girard V, Johansen S, Napoletano F, Dourlen P, Guillou L, Angebault-Prouteau C, Bernoud-Hubac N, Guichardant M, Brabet P, Mollereau B. Physiological and pathological roles of FATP-mediated lipid droplets in Drosophila and mice retina. PLoS Genet 2018; 14:e1007627. [PMID: 30199545 PMCID: PMC6147681 DOI: 10.1371/journal.pgen.1007627] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 09/20/2018] [Accepted: 08/13/2018] [Indexed: 11/18/2022] Open
Abstract
Increasing evidence suggests that dysregulation of lipid metabolism is associated with neurodegeneration in retinal diseases such as age-related macular degeneration and in brain disorders such as Alzheimer’s and Parkinson’s diseases. Lipid storage organelles (lipid droplets, LDs), accumulate in many cell types in response to stress, and it is now clear that LDs function not only as lipid stores but also as dynamic regulators of the stress response. However, whether these LDs are always protective or can also be deleterious to the cell is unknown. Here, we investigated the consequences of LD accumulation on retinal cell homeostasis under physiological and stress conditions in Drosophila and in mice. In wild-type Drosophila, we show that dFatp is required and sufficient for expansion of LD size in retinal pigment cells (RPCs) and that LDs in RPCs are required for photoreceptor survival during aging. Similarly, in mice, LD accumulation induced by RPC-specific expression of human FATP1 was non-toxic and promoted mitochondrial energy metabolism in RPCs and non-autonomously in photoreceptor cells. In contrast, the inhibition of LD accumulation by dFatp knockdown suppressed neurodegeneration in Aats-metFBDrosophila mutants, which carry elevated levels of reactive oxygen species (ROS). This suggests that abnormal turnover of LD may be toxic for photoreceptors cells of the retina under oxidative stress. Collectively, these findings indicate that FATP-mediated LD formation in RPCs promotes RPC and neuronal homeostasis under physiological conditions but could be deleterious for the photoreceptors under pathological conditions. Lipids are major cell constituents and are present in the membranes, as free lipids in the cytoplasm, or stored in vesicles called lipid droplets (LDs). Under conditions of stress, lipids stored in LDs can be released to serve as substrates for energy metabolism by mitochondria. However, lipid storage is dysregulated in many degenerative disorders such as age-related macular degeneration, Parkinson’s and Alzheimer’s diseases. Thus, it is unclear whether accumulation of LDs is protective or toxic for neuronal cells. To address this question, we examined the consequences of removal or enforced LD accumulation on the health of retinal cells in flies and mice. Like humans, fly and mouse retinas contain retinal pigment cells (RPC) that support the functions of neighboring photoreceptor cells. We found that overexpression of the fatty acid transport protein (FATP) in RPCs induced accumulation of LDs in both transgenic flies and mice. Moreover, LD accumulation in RPCs was not harmful for juxtaposed photoreceptors during aging, but was toxic under stress conditions. We propose that lipid storage promotes cellular communication that affects photoreceptor health.
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Affiliation(s)
- Daan M. Van Den Brink
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Aurélie Cubizolle
- Institut des Neurosciences de Montpellier, INSERM U1051, CHU St Eloi, Montpellier, France
- Université de Montpellier, Montpellier, France
| | - Gilles Chatelain
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Nathalie Davoust
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Victor Girard
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Simone Johansen
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
| | - Francesco Napoletano
- Molecular Oncology Unit, Department of Life Sciences, University of Trieste c/o Laboratorio Nazionale CIB, Area Science Park, Trieste, Italy
| | - Pierre Dourlen
- Institut Pasteur de Lille; Inserm, U1167, RID-AGE-Risk Factors and Molecular Determinants of Aging-Related Diseases; University Lille, U1167-Excellence Laboratory LabEx DISTALZ, Lille, France
| | - Laurent Guillou
- Institut des Neurosciences de Montpellier, INSERM U1051, CHU St Eloi, Montpellier, France
- Université de Montpellier, Montpellier, France
| | - Claire Angebault-Prouteau
- Institut des Neurosciences de Montpellier, INSERM U1051, CHU St Eloi, Montpellier, France
- INSERM U1046, UMR CNRS 9214, Université de Montpellier, CHRU de Montpellier, Montpellier, France
| | - Nathalie Bernoud-Hubac
- Univ Lyon, CarMeN laboratory, INSA Lyon, INSERM U1060, INRA U1397, Université Claude Bernard Lyon 1, F-69621, Villeurbanne, France
| | - Michel Guichardant
- Univ Lyon, CarMeN laboratory, INSA Lyon, INSERM U1060, INRA U1397, Université Claude Bernard Lyon 1, F-69621, Villeurbanne, France
| | - Philippe Brabet
- Institut des Neurosciences de Montpellier, INSERM U1051, CHU St Eloi, Montpellier, France
- Université de Montpellier, Montpellier, France
| | - Bertrand Mollereau
- Université de Lyon, ENSL, UCBL, CNRS, LBMC, UMS 3444 Biosciences Lyon Gerland, Lyon, France
- * E-mail:
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376
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Ackerman D, Tumanov S, Qiu B, Michalopoulou E, Spata M, Azzam A, Xie H, Simon MC, Kamphorst JJ. Triglycerides Promote Lipid Homeostasis during Hypoxic Stress by Balancing Fatty Acid Saturation. Cell Rep 2018; 24:2596-2605.e5. [PMID: 30184495 PMCID: PMC6137821 DOI: 10.1016/j.celrep.2018.08.015] [Citation(s) in RCA: 208] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 06/20/2018] [Accepted: 08/06/2018] [Indexed: 01/20/2023] Open
Abstract
Lipid droplets, which store triglycerides and cholesterol esters, are a prominent feature of clear cell renal cell carcinoma (ccRCC). Although their presence in ccRCC is critical for sustained tumorigenesis, their contribution to lipid homeostasis and tumor cell viability is incompletely understood. Here we show that disrupting triglyceride synthesis compromises the growth of both ccRCC tumors and ccRCC cells exposed to tumor-like conditions. Functionally, hypoxia leads to increased fatty acid saturation through inhibition of the oxygen-dependent stearoyl-CoA desaturase (SCD) enzyme. Triglycerides counter a toxic buildup of saturated lipids, primarily by releasing the unsaturated fatty acid oleate (the principal product of SCD activity) from lipid droplets into phospholipid pools. Disrupting this process derails lipid homeostasis, causing overproduction of toxic saturated ceramides and acyl-carnitines as well as activation of the NF-κB transcription factor. Our work demonstrates that triglycerides promote homeostasis by "buffering" specific fatty acids.
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Affiliation(s)
- Daniel Ackerman
- Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Sergey Tumanov
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow G61 1QH, UK
| | - Bo Qiu
- Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Evdokia Michalopoulou
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow G61 1QH, UK
| | - Michelle Spata
- Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Andrew Azzam
- Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Hong Xie
- Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - M Celeste Simon
- Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
| | - Jurre J Kamphorst
- Cancer Research UK Beatson Institute, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK; Institute of Cancer Sciences, University of Glasgow, Garscube Estate, Switchback Road, Glasgow G61 1QH, UK.
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377
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Costa G, Gildenhard M, Eldering M, Lindquist RL, Hauser AE, Sauerwein R, Goosmann C, Brinkmann V, Carrillo-Bustamante P, Levashina EA. Non-competitive resource exploitation within mosquito shapes within-host malaria infectivity and virulence. Nat Commun 2018; 9:3474. [PMID: 30150763 PMCID: PMC6110728 DOI: 10.1038/s41467-018-05893-z] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 08/01/2018] [Indexed: 11/22/2022] Open
Abstract
Malaria is a fatal human parasitic disease transmitted by a mosquito vector. Although the evolution of within-host malaria virulence has been the focus of many theoretical and empirical studies, the vector’s contribution to this process is not well understood. Here, we explore how within-vector resource exploitation would impact the evolution of within-host Plasmodium virulence. By combining within-vector dynamics and malaria epidemiology, we develop a mathematical model, which predicts that non-competitive parasitic resource exploitation within-vector restricts within-host parasite virulence. To validate our model, we experimentally manipulate mosquito lipid trafficking and gauge within-vector parasite development and within-host infectivity and virulence. We find that mosquito-derived lipids determine within-host parasite virulence by shaping development (quantity) and metabolic activity (quality) of transmissible sporozoites. Our findings uncover the potential impact of within-vector environment and vector control strategies on the evolution of malaria virulence. The evolution of within-host malaria virulence has been studied, but the vector’s contribution isn’t well understood. Here, Costa et al. show that non-competitive parasitic resource exploitation within-vector, in particular lipid trafficking, restricts within-host infectivity and virulence of the parasite.
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Affiliation(s)
- G Costa
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - M Gildenhard
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - M Eldering
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany.,Department of Medical Microbiology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - R L Lindquist
- Immunodynamics, German Rheumatism Research Centre (DRFZ), 10117, Berlin, Germany
| | - A E Hauser
- Immunodynamics, German Rheumatism Research Centre (DRFZ), 10117, Berlin, Germany.,Immune Dynamics and Intravital Microscopy, Charité-Universitätsmedizin, 10117, Berlin, Germany
| | - R Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - C Goosmann
- Microscopy Core Facility, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - V Brinkmann
- Microscopy Core Facility, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - P Carrillo-Bustamante
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany
| | - E A Levashina
- Vector Biology Unit, Max Planck Institute for Infection Biology (MPIIB), 10117, Berlin, Germany.
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378
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Denzel MS, Lapierre LR, Mack HID. Emerging topics in C. elegans aging research: Transcriptional regulation, stress response and epigenetics. Mech Ageing Dev 2018; 177:4-21. [PMID: 30134144 PMCID: PMC6696993 DOI: 10.1016/j.mad.2018.08.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 08/09/2018] [Accepted: 08/10/2018] [Indexed: 12/13/2022]
Abstract
Key discoveries in aging research have been made possible with the use of model organisms. Caenorhabditis elegans is a short-lived nematode that has become a well-established system to study aging. The practicality and powerful genetic manipulations associated with this metazoan have revolutionized our ability to understand how organisms age. 25 years after the publication of the discovery of the daf-2 gene as a genetic modifier of lifespan, C. elegans remains as relevant as ever in the quest to understand the process of aging. Nematode aging research has proven useful in identifying transcriptional regulators, small molecule signals, cellular mechanisms, epigenetic modifications associated with stress resistance and longevity, and lifespan-extending compounds. Here, we review recent discoveries and selected topics that have emerged in aging research using this incredible little worm.
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Affiliation(s)
- Martin S Denzel
- Max Planck Institute for Biology of Ageing, Cologne, Germany.
| | - Louis R Lapierre
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI, USA.
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379
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Impact of Obesity and Hyperglycemia on Placental Mitochondria. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:2378189. [PMID: 30186542 PMCID: PMC6112210 DOI: 10.1155/2018/2378189] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 06/13/2018] [Accepted: 07/12/2018] [Indexed: 01/08/2023]
Abstract
A lipotoxic placental environment is recognized in maternal obesity, with increased inflammation and oxidative stress. These changes might alter mitochondrial function, with excessive production of reactive oxygen species, in a vicious cycle leading to placental dysfunction and impaired pregnancy outcomes. Here, we hypothesize that maternal pregestational body mass index (BMI) and glycemic levels can alter placental mitochondria. We measured mitochondrial DNA (mtDNA, real-time PCR) and morphology (electron microscopy) in placentas of forty-seven singleton pregnancies at elective cesarean section. Thirty-seven women were normoglycemic: twenty-one normal-weight women, NW, and sixteen obese women, OB/GDM(−). Ten obese women had gestational diabetes mellitus, OB/GDM(+). OB/GDM(−) presented higher mtDNA levels versus NW, suggesting increased mitochondrial biogenesis in the normoglycemic obese group. These mitochondria showed similar morphology to NW. On the contrary, in OB/GDM(+), mtDNA was not significantly increased versus NW. Nevertheless, mitochondria showed morphological abnormalities, indicating impaired functionality. The metabolic response of the placenta to impairment in obese pregnancies can possibly vary depending on several parameters, resulting in opposite strains acting when insulin resistance of GDM occurs in the obese environment, characterized by inflammation and oxidative stress. Therefore, mitochondrial alterations represent a feature of obese pregnancies with changes in placental energetics that possibly can affect pregnancy outcomes.
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380
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Petan T, Jarc E, Jusović M. Lipid Droplets in Cancer: Guardians of Fat in a Stressful World. Molecules 2018; 23:molecules23081941. [PMID: 30081476 PMCID: PMC6222695 DOI: 10.3390/molecules23081941] [Citation(s) in RCA: 258] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 07/31/2018] [Accepted: 08/01/2018] [Indexed: 12/12/2022] Open
Abstract
Cancer cells possess remarkable abilities to adapt to adverse environmental conditions. Their survival during severe nutrient and oxidative stress depends on their capacity to acquire extracellular lipids and the plasticity of their mechanisms for intracellular lipid synthesis, mobilisation, and recycling. Lipid droplets, cytosolic fat storage organelles present in most cells from yeast to men, are emerging as major regulators of lipid metabolism, trafficking, and signalling in various cells and tissues exposed to stress. Their biogenesis is induced by nutrient and oxidative stress and they accumulate in various cancers. Lipid droplets act as switches that coordinate lipid trafficking and consumption for different purposes in the cell, such as energy production, protection against oxidative stress or membrane biogenesis during rapid cell growth. They sequester toxic lipids, such as fatty acids, cholesterol and ceramides, thereby preventing lipotoxic cell damage and engage in a complex relationship with autophagy. Here, we focus on the emerging mechanisms of stress-induced lipid droplet biogenesis; their roles during nutrient, lipotoxic, and oxidative stress; and the relationship between lipid droplets and autophagy. The recently discovered principles of lipid droplet biology can improve our understanding of the mechanisms that govern cancer cell adaptability and resilience to stress.
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Affiliation(s)
- Toni Petan
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana SI-1000, Slovenia.
| | - Eva Jarc
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana SI-1000, Slovenia.
- Jožef Stefan International Postgraduate School, Ljubljana SI-1000, Slovenia.
| | - Maida Jusović
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana SI-1000, Slovenia.
- Jožef Stefan International Postgraduate School, Ljubljana SI-1000, Slovenia.
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381
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Comeglio P, Cellai I, Mello T, Filippi S, Maneschi E, Corcetto F, Corno C, Sarchielli E, Morelli A, Rapizzi E, Bani D, Guasti D, Vannelli GB, Galli A, Adorini L, Maggi M, Vignozzi L. INT-767 prevents NASH and promotes visceral fat brown adipogenesis and mitochondrial function. J Endocrinol 2018; 238:107-127. [PMID: 29945982 DOI: 10.1530/joe-17-0557] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 05/29/2018] [Indexed: 12/12/2022]
Abstract
The bile acid receptors, farnesoid X receptor (FXR) and Takeda G-protein-coupled receptor 5 (TGR5), regulate multiple pathways, including glucose and lipid metabolism. In a rabbit model of high-fat diet (HFD)-induced metabolic syndrome, long-term treatment with the dual FXR/TGR5 agonist INT-767 reduces visceral adipose tissue accumulation, hypercholesterolemia and nonalcoholic steatohepatitis. INT-767 significantly improves the hallmarks of insulin resistance in visceral adipose tissue (VAT) and induces mitochondrial and brown fat-specific markers. VAT preadipocytes isolated from INT-767-treated rabbits, compared to preadipocytes from HFD, show increased mRNA expression of brown adipogenesis markers. In addition, INT-767 induces improved mitochondrial ultrastructure and dynamic, reduced superoxide production and improved insulin signaling and lipid handling in preadipocytes. Both in vivo and in vitro treatments with INT-767 counteract, in preadipocytes, the HFD-induced alterations by upregulating genes related to mitochondrial biogenesis and function. In preadipocytes, INT-767 behaves mainly as a TGR5 agonist, directly activating dose dependently the cAMP/PKA pathway. However, in vitro experiments also suggest that FXR activation by INT-767 contributes to the insulin signaling improvement. INT-767 treatment counteracts HFD-induced liver histological alterations and normalizes the increased pro-inflammatory genes. INT-767 also induces a significant reduction of fatty acid synthesis and fibrosis markers, while increasing lipid handling, insulin signaling and mitochondrial markers. In conclusion, INT-767 significantly counteracts HFD-induced liver and fat alterations, restoring insulin sensitivity and prompting preadipocytes differentiation toward a metabolically healthy phenotype.
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Affiliation(s)
- Paolo Comeglio
- Sexual Medicine and Andrology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
| | - Ilaria Cellai
- Sexual Medicine and Andrology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
| | - Tommaso Mello
- Gastroenterology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
| | - Sandra Filippi
- Interdepartmental Laboratory of Functional and Cellular Pharmacology of ReproductionDepartment of NEUROFARBA, University of Florence, Florence, Italy
| | - Elena Maneschi
- Sexual Medicine and Andrology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
| | - Francesca Corcetto
- Sexual Medicine and Andrology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
| | - Chiara Corno
- Sexual Medicine and Andrology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
| | - Erica Sarchielli
- Department of Experimental and Clinical MedicineUniversity of Florence, Florence, Italy
| | - Annamaria Morelli
- Department of Experimental and Clinical MedicineUniversity of Florence, Florence, Italy
| | - Elena Rapizzi
- Department of Experimental and Clinical Biomedical Sciences 'Mario Serio'University of Florence, Florence, Italy
| | - Daniele Bani
- Department of Experimental and Clinical MedicineUniversity of Florence, Florence, Italy
| | - Daniele Guasti
- Department of Experimental and Clinical MedicineUniversity of Florence, Florence, Italy
| | | | - Andrea Galli
- Gastroenterology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
| | | | - Mario Maggi
- Sexual Medicine and Andrology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
- I.N.B.B. - Istituto Nazionale Biostrutture e BiosistemiRome, Italy
| | - Linda Vignozzi
- Sexual Medicine and Andrology UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
- I.N.B.B. - Istituto Nazionale Biostrutture e BiosistemiRome, Italy
- Gynecologic Endocrinology Research UnitDepartment of Experimental and Clinical Biomedical Sciences 'Mario Serio', University of Florence, Florence, Italy
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382
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Lee J, Homma T, Kobayashi S, Ishii N, Fujii J. Unveiling systemic organ disorders associated with impaired lipid catabolism in fasted SOD1-deficient mice. Arch Biochem Biophys 2018; 654:163-171. [PMID: 30056077 DOI: 10.1016/j.abb.2018.07.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 07/08/2018] [Accepted: 07/25/2018] [Indexed: 12/12/2022]
Abstract
Oxidative stress triggers the formation of lipid droplets in the liver by stimulating lipogenesis and simultaneously suppresses lipoprotein secretion under hypernutritional conditions. Herein we report on the observation of systemic organ failure that is associated with lipid droplet accumulation in fasting, SOD1-knockout (KO) mice. Upon a three-day fasting period, the KO mice were observed to be vulnerable, could not be rescued by refeeding and had largely died, while wild-type mice were totally recovered. Visceral fat was rapidly consumed during fasting, which resulted in energy shortage and increased fatality in the KO mice. Lipid droplets had accumulated and continued to remain in KO mouse organs that routinely catalyze fatty acids via β-oxidation, even though the levels of free fatty acids and β-hydroxybutyrate, a ketone body, in blood plasma were less in KO mice compared to WT mice during the fasting period. The fasting-triggered organ failure in the KO mice was effectively mitigated by feeding a high calorie-diet for 2 weeks prior to fasting, even though the mice had an excessive accumulation of lipid droplets in the liver. These collective data suggest that the lipid-catabolizing system is the sensitive target of oxidative stress triggered by fasting conditions in the KO mice.
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Affiliation(s)
- Jaeyong Lee
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Japan
| | - Takujiro Homma
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Japan
| | - Sho Kobayashi
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Japan
| | - Naoki Ishii
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Japan
| | - Junichi Fujii
- Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Japan.
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383
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Daniele JR, Heydari K, Dillin A. Mitochondrial Subtype Identification and Characterization. CURRENT PROTOCOLS IN CYTOMETRY 2018; 85:e41. [PMID: 29944197 PMCID: PMC6039279 DOI: 10.1002/cpcy.41] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Healthy, functional mitochondria are central to many cellular and physiological phenomena, including aging, metabolism, and stress resistance. A key feature of healthy mitochondria is a high membrane potential (Δψ) or charge differential (i.e., proton gradient) between the matrix and inner mitochondrial membrane. Mitochondrial Δψ has been extensively characterized via flow cytometry of intact cells, which measures the average membrane potential within a cell. However, the characteristics of individual mitochondria differ dramatically even within a single cell, and thus interrogation of mitochondrial features at the organelle level is necessary to better understand and accurately measure heterogeneity. Here we describe a new flow cytometric methodology that enables the quantification and classification of mitochondrial subtypes (via their Δψ, size, and substructure) using the small animal model C. elegans. Future application of this methodology should allow research to discern the bioenergetic and mitochondrial component in a number of human disease and aging models, including, C. elegans, cultured cells, small animal models, and human biopsy samples. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Joseph R. Daniele
- Department of Molecular & Cellular Biology, University of
California, Berkeley, Berkeley, CA 94720
| | - Kartoosh Heydari
- LKS Flow Cytometry Core, Cancer Research Laboratory, University of
California, Berkeley, Berkeley, CA 94720
| | - Andrew Dillin
- Department of Molecular & Cellular Biology, University of
California, Berkeley, Berkeley, CA 94720
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384
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Abstract
PURPOSE OF REVIEW Intracellular lipid metabolism is a complex interplay of exogenous lipid handling, trafficking, storage, lipolysis, and export. Recent work has implicated the cellular degradative process called autophagy in several aspects of lipid metabolism. We will discuss both the classical and novel roles of autophagy and the autophagic machinery in this setting. RECENT FINDINGS The delivery of lipid droplets to lysosomes for hydrolysis, named lipophagy, was the first described functional role for autophagy in lipid metabolism. The molecular machinery and regulation of this selective form of macroautophagy is beginning to be discovered and has the potential to shed enormous light on intracellular lipolysis. Yet, the autophagic machinery appears to also be coopted for alternative roles that include interaction with cytosolic lipolysis pathways, supply and expansion of lipid droplets, and lipoprotein trafficking. Additionally, lesser studied forms of autophagy called microautophagy and chaperone-mediated autophagy have distinct roles in lipid handling that also intersect with classical macroautophagy. The integration of current knowledge in these areas into a holistic understanding of intracellular lipid metabolism will be a goal of this review. SUMMARY As the field of autophagy has evolved and expanded to include functional roles in various aspects of cellular degradation, so has its role in intracellular lipid metabolism. Understanding the mechanisms underlying these classical and alternative roles of autophagy will not only enhance our knowledge in lipid biology but also provide new avenues of translation to human lipid disorders.
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Affiliation(s)
- Xiangyu Zhang
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- John Cochran VA Medical Center, St. Louis, Missouri, USA
| | - Trent D. Evans
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Se-Jin Jeong
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- John Cochran VA Medical Center, St. Louis, Missouri, USA
| | - Babak Razani
- Cardiovascular Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, USA
- John Cochran VA Medical Center, St. Louis, Missouri, USA
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385
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Impaired Fasting-Induced Adaptive Lipid Droplet Biogenesis in Liver-Specific Atg5-Deficient Mouse Liver Is Mediated by Persistent Nuclear Factor-Like 2 Activation. THE AMERICAN JOURNAL OF PATHOLOGY 2018; 188:1833-1846. [PMID: 29803835 DOI: 10.1016/j.ajpath.2018.04.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/08/2018] [Accepted: 04/19/2018] [Indexed: 12/22/2022]
Abstract
Lipid droplets (LDs) are intracellular organelles that store neutral lipids as energy reservoir. Recent studies suggest that autophagy is important in maintaining the homeostasis of intracellular LDs by either regulating the biogenesis of LDs, mobilization of fatty acids, or degradation of LDs in cultured cells. Increasing evidence also supports a role of autophagy in regulating glucose and lipid metabolism in vivo in mammals. In response to fasting/starvation, lipids are mobilized from the adipose tissue to the liver, which increases the number of intracellular LDs and stimulates fatty acid oxidation and ketogenesis. However, it is still controversial and unclear how impaired autophagy in hepatocytes affects the biogenesis of LDs in mouse livers. In the present study, it was demonstrated that hepatic autophagy-deficient (L-Atg)5 knockout mice had impaired adaptation to fasting-induced hepatic biogenesis of LDs. The maladaptation to fasting-induced hepatic biogenesis of LDs in L-Atg5 knockout mouse livers was not due to hepatic changes of de novo lipogenesis, secretion of very-low-density lipoprotein or fatty acid β-oxidation, but it was due to persistent nuclear factor-like 2 activation because biogenesis of LDs restored in L-Atg5/nuclear factor-like 2 double-knockout mice.
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386
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Henne WM, Reese ML, Goodman JM. The assembly of lipid droplets and their roles in challenged cells. EMBO J 2018; 37:embj.201898947. [PMID: 29789390 DOI: 10.15252/embj.201898947] [Citation(s) in RCA: 180] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 03/08/2018] [Accepted: 03/22/2018] [Indexed: 12/14/2022] Open
Abstract
Cytoplasmic lipid droplets are important organelles in nearly every eukaryotic and some prokaryotic cells. Storing and providing energy is their main function, but they do not work in isolation. They respond to stimuli initiated either on the cell surface or in the cytoplasm as conditions change. Cellular stresses such as starvation and invasion are internal insults that evoke changes in droplet metabolism and dynamics. This review will first outline lipid droplet assembly and then discuss how droplets respond to stress and in particular nutrient starvation. Finally, the role of droplets in viral and microbial invasion will be presented, where an unresolved issue is whether changes in droplet abundance promote the invader, defend the host, to try to do both. The challenges of stress and infection are often accompanied by changes in physical contacts between droplets and other organelles. How these changes may result in improving cellular physiology, an ongoing focus in the field, is discussed.
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Affiliation(s)
- W Mike Henne
- Department of Cell Biology, University of Texas Southwestern Medical School, Dallas, TX, USA
| | - Michael L Reese
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX, USA
| | - Joel M Goodman
- Department of Pharmacology, University of Texas Southwestern Medical School, Dallas, TX, USA
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387
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Verma M, Pandey S, Bhat IA, Mukesh B, Anand J, Chandra V, Sharma GT. Impact of l-carnitine on lipid content and post thaw survivability of buffalo embryos produced in vitro. Cryobiology 2018; 82:99-105. [PMID: 29626464 DOI: 10.1016/j.cryobiol.2018.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 03/01/2018] [Accepted: 04/03/2018] [Indexed: 02/01/2023]
Abstract
The aim of the present study was to see the impact of L-Carnitine (LC) on lipid biosynthesis and metabolism of buffalo embryos, and post thaw blastocyst survivability. In vitro fertilized (IVF) embryos were derived from slaughterhouse derived COCs and cultured in different doses of LC i.e. 0, 1 mM, 1.5 mM, 2 mM starting at 48 h post IVF. Blastocyst rate was significantly (p < 0.05) higher in 1.5 mM group than control and 1.0 mM group. Lipid content was measured indirectly by fluorescent intensity of lipid droplets after Nile red staining, and it was lower (p < 0.05) in treated than control groups. CPT1B, DGAT2 and DGAT1 mRNA expression was up regulated (p < 0.05) while AMPKg1 expression was down regulated in 1.5 mM and 2 mM groups compared to other groups (p < 0.05). mRNA expression of GLUT1, OCT4 and IFN-tau was higher (P < 0.05) in 1.5 mM group than the control group. Expression of BAX was down regulated at 1.5 mM LC. Blastocyts were vitrified by a modified OPS method and post thaw survivability of blastocysts was higher (P < 0.05) in 1.5 mM LC than other groups. In post thaw blastocysts, mRNA expression of GLUT1, OCT4 and IFN-tau was higher (P < 0.05) in 1.5 mM than other groups. Thus, it can be concluded that supplementation of l-carnitine (1.5 mM) in embryo culture media improved the quality of buffalo embryo production and post thaw blastocysts survivability by reducing fatty acid synthesis, enhancing fatty acid metabolism, and reducing lipid droplet formation.
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Affiliation(s)
- Megha Verma
- Division of Physiology & Climatology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243 122, UP, India
| | - Sriti Pandey
- Division of Physiology & Climatology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243 122, UP, India
| | - Irfan A Bhat
- Division of Physiology & Climatology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243 122, UP, India
| | - B Mukesh
- Division of Physiology & Climatology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243 122, UP, India
| | - J Anand
- Division of Physiology & Climatology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243 122, UP, India
| | - Vikash Chandra
- Division of Physiology & Climatology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243 122, UP, India.
| | - G Taru Sharma
- Division of Physiology & Climatology, ICAR-Indian Veterinary Research Institute, Izatnagar, 243 122, UP, India
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388
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Henne WM, Hariri H. Endoplasmic Reticulum-Vacuole Contact Sites "Bloom" With Stress-Induced Lipid Droplets. ACTA ACUST UNITED AC 2018; 1. [PMID: 30112463 PMCID: PMC6088805 DOI: 10.1177/2515256418756112] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lipid droplets (LDs) serve as specialized cytoplasmic organelles that harbor energy-rich lipids for long-term storage and may be mobilized as nutrient sources during extended starvation. How cells coordinate LD biogenesis and utilization in response to fluctuations in nutrient availability remains poorly understood. Here, we discuss our recent work revealing how yeast spatially organize LD budding at organelle contacts formed between the endoplasmic reticulum and yeast vacuole/lysosome (sites known as nucleus-vacuole junctions [NVJs]). During times of imminent nutrient exhaustion, we observe blooms of stress-induced LDs surrounding the NVJ and find that this LD clustering is regulated by NVJ-resident protein Mdm1. We also discuss several emerging studies revealing specific proteins that demarcate a subpopulation of NVJ-associated LDs. Collectively, these studies reveal a previously unappreciated role for the spatial compartmentalization of LDs at organelle contacts and highlight an important role for interorganellar cross talk in LD dynamics under times of nutritional stress.
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Affiliation(s)
- W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Hanaa Hariri
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, USA
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389
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Mitochondria Restrict Growth of the Intracellular Parasite Toxoplasma gondii by Limiting Its Uptake of Fatty Acids. Cell Metab 2018; 27:886-897.e4. [PMID: 29617646 DOI: 10.1016/j.cmet.2018.02.018] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 01/05/2018] [Accepted: 02/20/2018] [Indexed: 01/27/2023]
Abstract
How intracellular pathogens acquire essential non-diffusible host metabolites and whether the host cell counteracts the siphoning of these nutrients by its invaders are open questions. Here we show that host mitochondria fuse during infection by the intracellular parasite Toxoplasma gondii to limit its uptake of fatty acids (FAs). A combination of genetics and imaging of FA trafficking indicates that Toxoplasma infection triggers lipophagy, the autophagy of host lipid droplets (LDs), to secure cellular FAs essential for its proliferation. Indeed, Toxoplasma FA siphoning and growth are reduced in host cells genetically deficient for autophagy or triglyceride depots. Conversely, Toxoplasma FA uptake and proliferation are increased in host cells lacking mitochondrial fusion, required for efficient mitochondrial FA oxidation, or where mitochondrial FA oxidation is pharmacologically inhibited. Thus, mitochondrial fusion can be regarded as a cellular defense mechanism against intracellular parasites, by limiting Toxoplasma access to host nutrients liberated by lipophagy.
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390
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Benador IY, Veliova M, Mahdaviani K, Petcherski A, Wikstrom JD, Assali EA, Acín-Pérez R, Shum M, Oliveira MF, Cinti S, Sztalryd C, Barshop WD, Wohlschlegel JA, Corkey BE, Liesa M, Shirihai OS. Mitochondria Bound to Lipid Droplets Have Unique Bioenergetics, Composition, and Dynamics that Support Lipid Droplet Expansion. Cell Metab 2018; 27:869-885.e6. [PMID: 29617645 PMCID: PMC5969538 DOI: 10.1016/j.cmet.2018.03.003] [Citation(s) in RCA: 400] [Impact Index Per Article: 57.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Revised: 01/07/2018] [Accepted: 03/13/2018] [Indexed: 01/05/2023]
Abstract
Mitochondria associate with lipid droplets (LDs) in fat-oxidizing tissues, but the functional role of these peridroplet mitochondria (PDM) is unknown. Microscopic observation of interscapular brown adipose tissue reveals that PDM have unique protein composition and cristae structure and remain adherent to the LD in the tissue homogenate. We developed an approach to isolate PDM based on their adherence to LDs. Comparison of purified PDM to cytoplasmic mitochondria reveals that (1) PDM have increased pyruvate oxidation, electron transport, and ATP synthesis capacities; (2) PDM have reduced β-oxidation capacity and depart from LDs upon activation of brown adipose tissue thermogenesis and β-oxidation; (3) PDM support LD expansion as Perilipin5-induced recruitment of mitochondria to LDs increases ATP synthase-dependent triacylglyceride synthesis; and (4) PDM maintain a distinct protein composition due to uniquely low fusion-fission dynamics. We conclude that PDM represent a segregated mitochondrial population with unique structure and function that supports triacylglyceride synthesis.
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Affiliation(s)
- Ilan Y Benador
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Michaela Veliova
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Kiana Mahdaviani
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Anton Petcherski
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Jakob D Wikstrom
- Dermatology and Venereology Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Dermato-Venereology, Karolinska University Hospital, Stockholm, Sweden
| | - Essam A Assali
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Department of Clinical Biochemistry, School of Medicine, Ben Gurion University of The Negev, Beer-Sheva, Israel
| | - Rebeca Acín-Pérez
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Michaël Shum
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Marcus F Oliveira
- Institute of Medical Biochemistry Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Saverio Cinti
- Department of Experimental and Clinical Medicine, University of Ancona, Ancona, Italy
| | - Carole Sztalryd
- Department of Medicine, School of Medicine, University of Maryland Baltimore, MD, USA
| | - William D Barshop
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Barbara E Corkey
- Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Marc Liesa
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
| | - Orian S Shirihai
- Division of Endocrinology, Department of Medicine, and Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Obesity Research Center, Department of Medicine, Boston University School of Medicine, Boston, MA, USA; Department of Clinical Biochemistry, School of Medicine, Ben Gurion University of The Negev, Beer-Sheva, Israel.
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391
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Callegari S, Dennerlein S. Sensing the Stress: A Role for the UPR mt and UPR am in the Quality Control of Mitochondria. Front Cell Dev Biol 2018; 6:31. [PMID: 29644217 PMCID: PMC5882792 DOI: 10.3389/fcell.2018.00031] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 03/12/2018] [Indexed: 01/01/2023] Open
Abstract
Mitochondria exist as compartmentalized units, surrounded by a selectively permeable double membrane. Within is contained the mitochondrial genome and protein synthesis machinery, required for the synthesis of OXPHOS components and ultimately, ATP production. Despite their physical barrier, mitochondria are tightly integrated into the cellular environment. A constant flow of information must be maintained to and from the mitochondria and the nucleus, to ensure mitochondria are amenable to cell metabolic requirements and also to feedback on their functional state. This review highlights the pathways by which mitochondrial stress is signaled to the nucleus, with a particular focus on the mitochondrial unfolded protein response (UPRmt) and the unfolded protein response activated by the mistargeting of proteins (UPRam). Although these pathways were originally discovered to alleviate proteotoxic stress from the accumulation of mitochondrial-targeted proteins that are misfolded or unimported, we review recent findings indicating that the UPRmt can also sense defects in mitochondrial translation. We further discuss the regulation of OXPHOS assembly and speculate on a possible role for mitochondrial stress pathways in sensing OXPHOS biogenesis.
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Affiliation(s)
- Sylvie Callegari
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
| | - Sven Dennerlein
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
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392
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Tomin T, Fritz K, Gindlhuber J, Waldherr L, Pucher B, Thallinger GG, Nomura DK, Schittmayer M, Birner-Gruenberger R. Deletion of Adipose Triglyceride Lipase Links Triacylglycerol Accumulation to a More-Aggressive Phenotype in A549 Lung Carcinoma Cells. J Proteome Res 2018; 17:1415-1425. [PMID: 29457907 DOI: 10.1021/acs.jproteome.7b00782] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adipose triglyceride lipase (ATGL) catalyzes the rate limiting step in triacylglycerol breakdown in adipocytes but is expressed in most tissues. The enzyme was shown to be lost in many human tumors, and its loss may play a role in early stages of cancer development. Here, we report that loss of ATGL supports a more-aggressive cancer phenotype in a model system in which ATGL was deleted in A549 lung cancer cells by CRISPR/Cas9. We observed that loss of ATGL led to triacylglycerol accumulation in lipid droplets and higher levels of cellular phospholipid and bioactive lipid species (lyso- and ether-phospholipids). Label-free quantitative proteomics revealed elevated expression of the pro-oncogene SRC kinase in ATGL depleted cells, which was also found on mRNA level and confirmed on protein level by Western blot. Consistently, higher expression of phosphorylated (active) SRC (Y416 phospho-SRC) was observed in ATGL-KO cells. Cells depleted of ATGL migrated faster, which was dependent on SRC kinase activity. We propose that loss of ATGL may thus increase cancer aggressiveness by activation of pro-oncogenic signaling via SRC kinase and increased levels of bioactive lipids.
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Affiliation(s)
- Tamara Tomin
- Research Unit Functional Proteomics and Metabolic Pathways , Institute of Pathology, Medical University of Graz , 8010 Graz , Austria.,Omics Center Graz, BioTechMed-Graz , 8010 Graz , Austria
| | - Katarina Fritz
- Research Unit Functional Proteomics and Metabolic Pathways , Institute of Pathology, Medical University of Graz , 8010 Graz , Austria.,Omics Center Graz, BioTechMed-Graz , 8010 Graz , Austria
| | - Juergen Gindlhuber
- Research Unit Functional Proteomics and Metabolic Pathways , Institute of Pathology, Medical University of Graz , 8010 Graz , Austria.,Omics Center Graz, BioTechMed-Graz , 8010 Graz , Austria
| | - Linda Waldherr
- Research Unit Functional Proteomics and Metabolic Pathways , Institute of Pathology, Medical University of Graz , 8010 Graz , Austria.,Omics Center Graz, BioTechMed-Graz , 8010 Graz , Austria
| | - Bettina Pucher
- Omics Center Graz, BioTechMed-Graz , 8010 Graz , Austria.,Institute of Computational Biotechnology, Graz University of Technology , 8010 Graz , Austria
| | - Gerhard G Thallinger
- Omics Center Graz, BioTechMed-Graz , 8010 Graz , Austria.,Institute of Computational Biotechnology, Graz University of Technology , 8010 Graz , Austria
| | | | - Matthias Schittmayer
- Research Unit Functional Proteomics and Metabolic Pathways , Institute of Pathology, Medical University of Graz , 8010 Graz , Austria.,Omics Center Graz, BioTechMed-Graz , 8010 Graz , Austria
| | - Ruth Birner-Gruenberger
- Research Unit Functional Proteomics and Metabolic Pathways , Institute of Pathology, Medical University of Graz , 8010 Graz , Austria.,Omics Center Graz, BioTechMed-Graz , 8010 Graz , Austria
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393
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Jarc E, Kump A, Malavašič P, Eichmann TO, Zimmermann R, Petan T. Lipid droplets induced by secreted phospholipase A2 and unsaturated fatty acids protect breast cancer cells from nutrient and lipotoxic stress. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:247-265. [DOI: 10.1016/j.bbalip.2017.12.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 11/13/2017] [Accepted: 12/07/2017] [Indexed: 12/12/2022]
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394
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Williams JA, Ding WX. Mechanisms, pathophysiological roles and methods for analyzing mitophagy - recent insights. Biol Chem 2018; 399:147-178. [PMID: 28976892 DOI: 10.1515/hsz-2017-0228] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 09/13/2017] [Indexed: 12/17/2022]
Abstract
In 2012, we briefly summarized the mechanisms, pathophysiological roles and methods for analyzing mitophagy. As then, the mitophagy field has continued to grow rapidly, and many new molecular mechanisms regulating mitophagy and molecular tools for monitoring mitophagy have been discovered and developed. Therefore, the purpose of this review is to update information regarding these advances in mitophagy while focusing on basic molecular mechanisms of mitophagy in different organisms and its pathophysiological roles. We also discuss the advantage and limitations of current methods to monitor and quantify mitophagy in cultured cells and in vivo mouse tissues.
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Affiliation(s)
- Jessica A Williams
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City, KS 66160, USA
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS 66160, USA
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395
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Abstract
Long considered inert fat storage depots, it has become clear that lipid droplets (LDs) are bona fide organelles. Like other organelles, they have a characteristic complement of proteins and lipids, and undergo a life cycle that includes biogenesis, maturation, interactions with other organelles, and turnover. I will discuss recent insights into mechanisms governing the life cycle of LDs, and compare and contrast the LD life cycle with that of other metabolic organelles such as mitochondria, peroxisomes, and autophagosomes, highlighting open questions in the field.
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Affiliation(s)
- Sarah Cohen
- University of North Carolina, Chapel Hill, NC, United States.
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396
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Bersuker K, Peterson CWH, To M, Sahl SJ, Savikhin V, Grossman EA, Nomura DK, Olzmann JA. A Proximity Labeling Strategy Provides Insights into the Composition and Dynamics of Lipid Droplet Proteomes. Dev Cell 2017; 44:97-112.e7. [PMID: 29275994 DOI: 10.1016/j.devcel.2017.11.020] [Citation(s) in RCA: 238] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/18/2017] [Accepted: 11/27/2017] [Indexed: 01/06/2023]
Abstract
Lipid droplet (LD) functions are regulated by a complement of integral and peripheral proteins that associate with the bounding LD phospholipid monolayer. Defining the composition of the LD proteome has remained a challenge due to the presence of contaminating proteins in LD-enriched buoyant fractions. To overcome this limitation, we developed a proximity labeling strategy that exploits LD-targeted APEX2 to biotinylate LD proteins in living cells. Application of this approach to two different cell types identified the vast majority of previously validated LD proteins, excluded common contaminating proteins, and revealed new LD proteins. Moreover, quantitative analysis of LD proteome dynamics uncovered a role for endoplasmic reticulum-associated degradation in controlling the composition of the LD proteome. These data provide an important resource for future LD studies and demonstrate the utility of proximity labeling to study the regulation of LD proteomes.
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Affiliation(s)
- Kirill Bersuker
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Clark W H Peterson
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Milton To
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Steffen J Sahl
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Victoria Savikhin
- SLAC National Accelerator Center, SSRL, Menlo Park, CA 94025, USA; Stanford Electrical Engineering Department, Stanford University, Stanford, CA 94305, USA
| | - Elizabeth A Grossman
- Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Daniel K Nomura
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA; Departments of Chemistry and Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - James A Olzmann
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA 94720, USA.
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397
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Abstract
In this issue of Developmental Cell, Nguyen et al. (2017) show that lipid droplets serve a dual purpose during starvation. First, they act as an energy source by supplying fatty acids for mitochondrial β oxidation. Second, they sequester toxic lipids that arise during autophagic degradation of membranous organelles, thereby protecting mitochondria.
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Affiliation(s)
- Till Klecker
- Zellbiologie, Universität Bayreuth, 95440 Bayreuth, Germany.
| | - Ralf J Braun
- Zellbiologie, Universität Bayreuth, 95440 Bayreuth, Germany
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398
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Li Y, Zong WX, Ding WX. Recycling the danger via lipid droplet biogenesis after autophagy. Autophagy 2017; 13:1995-1997. [PMID: 28873005 PMCID: PMC5788485 DOI: 10.1080/15548627.2017.1371394] [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: 08/08/2017] [Revised: 08/10/2017] [Accepted: 08/18/2017] [Indexed: 01/22/2023] Open
Abstract
Fatty acids are an important cellular energy source under starvation conditions. However, excessive free fatty acids (FFAs) in the cytoplasm cause lipotoxicity. Therefore, it is important to understand the mechanisms by which cells mobilize lipids and maintain a homeostatic level of fatty acids. Recent evidence suggests that cells can break down lipid droplets (LDs), the intracellular organelles that store neutral lipids, via PNPLA2/adipose triglyceride lipase and a selective type of macroautophagy/autophagy termed lipophagy, to release FFAs under starvation conditions. FFAs generated from LD catabolism are either transported to mitochondria for β-oxidation or converted back to LDs. The biogenesis of LDs under starvation conditions is mediated by autophagic degradation of membranous organelles and requires diacylglycerol O-acyltransferase 1, which serves as an adaptive cellular protective mechanism against lipotoxicity.
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Affiliation(s)
- Yuan Li
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
| | - Wei-Xing Zong
- Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers University, Piscataway, NJ, USA
| | - Wen-Xing Ding
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA
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399
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Thelen AM, Zoncu R. Emerging Roles for the Lysosome in Lipid Metabolism. Trends Cell Biol 2017; 27:833-850. [PMID: 28838620 DOI: 10.1016/j.tcb.2017.07.006] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 07/28/2017] [Accepted: 07/31/2017] [Indexed: 12/20/2022]
Abstract
Precise regulation of lipid biosynthesis, transport, and storage is key to the homeostasis of cells and organisms. Cells rely on a sophisticated but poorly understood network of vesicular and nonvesicular transport mechanisms to ensure efficient delivery of lipids to target organelles. The lysosome stands at the crossroads of this network due to its ability to process and sort exogenous and endogenous lipids. The lipid-sorting function of the lysosome is intimately connected to its recently discovered role as a metabolic command-and-control center, which relays multiple nutrient cues to the master growth regulator, mechanistic target of rapamycin complex (mTORC)1 kinase. In turn, mTORC1 potently drives anabolic processes, including de novo lipid synthesis, while inhibiting lipid catabolism. Here, we describe the dual role of the lysosome in lipid transport and biogenesis, and we discuss how integration of these two processes may play important roles both in normal physiology and in disease.
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Affiliation(s)
- Ashley M Thelen
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA
| | - Roberto Zoncu
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; The Paul F. Glenn Center for Aging Research at the University of California, Berkeley, Berkeley, CA 94720, USA.
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