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Komiya Y, Iseki S, Ochiai M, Takahashi Y, Yokoyama I, Suzuki T, Tatsumi R, Sawano S, Mizunoya W, Arihara K. Dietary oleic acid intake increases the proportion of type 1 and 2X muscle fibers in mice. Sci Rep 2024; 14:755. [PMID: 38191891 PMCID: PMC10774392 DOI: 10.1038/s41598-023-50464-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 12/20/2023] [Indexed: 01/10/2024] Open
Abstract
Skeletal muscle is one of the largest metabolic tissues in mammals and is composed of four different types of muscle fibers (types 1, 2A, 2X, and 2B); however, type 2B is absent in humans. Given that slow-twitch fibers are superior to fast-twitch fibers in terms of oxidative metabolism and are rich in mitochondria, shift of muscle fiber types in direction towards slower fiber types improves metabolic disorders and endurance capacity. We previously had reported that oleic acid supplementation increases type 1 fiber formation in C2C12 myotubes; however, its function still remains unclear. This study aimed to determine the effect of oleic acid on the muscle fiber types and endurance capacity. An in vivo mouse model was used, and mice were fed a 10% oleic acid diet for 4 weeks. Two different skeletal muscles, slow soleus muscle with the predominance of slow-twitch fibers and fast extensor digitorum longus (EDL) muscle with the predominance of fast-twitch fibers, were used. We found that dietary oleic acid intake improved running endurance and altered fiber type composition of muscles, the proportion of type 1 and 2X fibers increased in the soleus muscle and type 2X increased in the EDL muscle. The fiber type shift in the EDL muscle was accompanied by an increased muscle TAG content. In addition, blood triacylglycerol (TAG) and non-esterified fatty acid levels decreased during exercise. These changes suggested that lipid utilization as an energy substrate was enhanced by oleic acid. Increased proliferator-activated receptor γ coactivator-1β protein levels were observed in the EDL muscle, which potentially enhanced the fiber type transitions towards type 2X and muscle TAG content. In conclusion, dietary oleic acid intake improved running endurance with the changes of muscle fiber type shares in mice. This study elucidated a novel functionality of oleic acid in skeletal muscle fiber types. Further studies are required to elucidate the underlying mechanisms. Our findings have the potential to contribute to the field of health and sports science through nutritional approaches, such as the development of supplements aimed at improving muscle function.
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Affiliation(s)
- Yusuke Komiya
- Laboratory of Food Function and Safety, Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Japan.
| | - Shugo Iseki
- Laboratory of Food Function and Safety, Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Japan
| | - Masaru Ochiai
- Laboratory of Animal and Human Nutritional Physiology, Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Japan
| | - Yume Takahashi
- Laboratory of Food Function and Safety, Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Japan
| | - Issei Yokoyama
- Laboratory of Food Function and Safety, Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Japan
| | - Takahiro Suzuki
- Laboratory of Muscle and Meat Science, Department of Animal and Marine Bioresource Sciences, Faculty of Agriculture, Graduate School of Agriculture, Kyushu University, Fukuoka, Japan
| | - Ryuichi Tatsumi
- Laboratory of Muscle and Meat Science, Department of Animal and Marine Bioresource Sciences, Faculty of Agriculture, Graduate School of Agriculture, Kyushu University, Fukuoka, Japan
| | - Shoko Sawano
- Laboratory of Food Health Science, Department of Food and Life Science, School of Life and Environmental Science, Azabu University, Sagamihara, Japan
| | - Wataru Mizunoya
- Laboratory of Food Science, Department of Animal Science and Biotechnology, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | - Keizo Arihara
- Laboratory of Food Function and Safety, Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, Japan
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2
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Schleh MW, Ahn C, Ryan BJ, Chugh OK, Luker AT, Luker KE, Gillen JB, Ludzki AC, Van Pelt DW, Pitchford LM, Zhang T, Rode T, Howton SM, Burant CF, Horowitz JF. Both moderate- and high-intensity exercise training increase intramyocellular lipid droplet abundance and modify myocellular distribution in adults with obesity. Am J Physiol Endocrinol Metab 2023; 325:E466-E479. [PMID: 37729021 PMCID: PMC10864005 DOI: 10.1152/ajpendo.00093.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 09/12/2023] [Accepted: 09/12/2023] [Indexed: 09/22/2023]
Abstract
Exercise training modifies lipid metabolism in skeletal muscle, but the effect of exercise training on intramyocellular lipid droplet (LD) abundance, size, and intracellular distribution in adults with obesity remains elusive. This study compared high-intensity interval training (HIIT) with more conventional moderate-intensity continuous training (MICT) on intramyocellular lipid content, as well as LD characteristics (size and number) and abundance within the intramyofibrillar (IMF) and subsarcolemmal (SS) regions of type I and type II skeletal muscle fibers in adults with obesity. Thirty-six adults with obesity [body mass index (BMI) = 33 ± 3 kg/m2] completed 12 wk (4 days/wk) of either HIIT (10 × 1 min, 90% HRmax + 1-min active recovery; n = 19) or MICT (45-min steady-state exercise, 70% HRmax; n = 17), while on a weight-maintaining diet throughout training. Skeletal muscle biopsies were collected from the vastus lateralis before and after training, and intramyocellular lipid content and intracellular LD distribution were measured by immunofluorescence microscopy. Both MICT and HIIT increased total intramyocellular lipid content by more than 50% (P < 0.01), which was attributed to a greater LD number per µm2 in the IMF region of both type I and type II muscle fibers (P < 0.01). Our findings also suggest that LD lipophagy (autophagy-mediated LD degradation) may be transiently upregulated the day after the last exercise training session (P < 0.02 for both MICT and HIIT). In summary, exercise programs for adults with obesity involving either MICT or HIIT increased skeletal muscle LD abundance via a greater number of LDs in the IMF region of the myocyte, thereby providing more lipid in close proximity to the site of energy production during exercise.NEW & NOTEWORTHY In this study, 12 wk of either moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) enhanced skeletal muscle lipid abundance by increasing lipid droplet number within the intramyofibrillar (IMF) region of muscle. Because the IMF associates with high energy production during muscle contraction, this adaptation may enhance lipid oxidation during exercise. Despite differences in training intensity and energy expenditure between MICT and HIIT, their effects on muscle lipid abundance and metabolism were remarkably similar.
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Affiliation(s)
- Michael W Schleh
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Cheehoon Ahn
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Benjamin J Ryan
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Olivia K Chugh
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Austin T Luker
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Kathryn E Luker
- Department of Radiology, Center for Molecular Imaging, University of Michigan, Ann Arbor, Michigan, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, United States
| | - Jenna B Gillen
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Alison C Ludzki
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Douglas W Van Pelt
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Lisa M Pitchford
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Tao Zhang
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Thomas Rode
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Suzette M Howton
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Charles F Burant
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States
| | - Jeffrey F Horowitz
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
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3
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Palmitic Acid Inhibits Myogenic Activity and Expression of Myosin Heavy Chain MHC IIb in Muscle Cells through Phosphorylation-Dependent MyoD Inactivation. Int J Mol Sci 2023; 24:ijms24065847. [PMID: 36982919 PMCID: PMC10054354 DOI: 10.3390/ijms24065847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 03/22/2023] Open
Abstract
Sarcopenia associated with aging and obesity is characterized by the atrophy of fast-twitch muscle fibers and an increase in intramuscular fat deposits. However, the mechanism of fast-twitch fiber-specific atrophy remains unclear. In this study, we aimed to assess the effect of palmitic acid (PA), the most common fatty acid component of human fat, on muscle fiber type, focusing on the expression of fiber-type-specific myosin heavy chain (MHC). Myotubes differentiated from C2C12 myoblasts were treated with PA. The PA treatment inhibited myotube formation and hypertrophy while reducing the gene expression of MHC IIb and IIx, specific isoforms of fast-twitch fibers. Consistent with this, a significant suppression of MHC IIb protein expression in PA-treated cells was observed. A reporter assay using plasmids containing the MHC IIb gene promoter revealed that the PA-induced reduction in MHC IIb gene expression was caused by the suppression of MyoD transcriptional activity through its phosphorylation. Treatment with a specific protein kinase C (PKC) inhibitor recovered the reduction in MHC IIb gene expression levels in PA-treated cells, suggesting the involvement of the PA-induced activation of PKC. Thus, PA selectively suppresses the mRNA and protein expression of fast-twitch MHC by modulating MyoD activity. This finding provides a potential pathogenic mechanism for age-related sarcopenia.
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Lipid-droplet associated mitochondria promote fatty-acid oxidation through a distinct bioenergetic pattern in male Wistar rats. Nat Commun 2023; 14:766. [PMID: 36765117 PMCID: PMC9918515 DOI: 10.1038/s41467-023-36432-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 02/01/2023] [Indexed: 02/12/2023] Open
Abstract
Mitochondria empower the liver to regulate lipid homeostasis by enabling fatty acid oxidation during starvation and lipogenesis during nutrient-rich conditions. It is unknown if mitochondria can seamlessly regulate these two distinct processes or if two discrete populations of mitochondria achieve these two functions in the liver. For the first time in the liver, we report the isolation of two distinct populations of mitochondria from male Wistar rats on an ad-libitum diet: cytoplasmic mitochondria and lipid droplet-associated mitochondria. Our studies show that while lipid droplet mitochondria exhibit higher fatty acid oxidation and are marked by enhanced levels of pACC2, MFN2, and CPT1 activity, cytoplasmic mitochondria are associated with higher respiration capacity. Notably, lipid droplet-associated mitochondria isolated from a non-alcoholic fatty liver disease (NAFLD) rat model are compromised for fatty acid oxidation. We demonstrate the importance of functional segregation of mitochondria as any aberration in lipid droplet-associated mitochondria may lead to NAFLD.
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Fachada V, Rahkila P, Fachada N, Turpeinen T, Kujala UM, Kainulainen H. Enlarged PLIN5-uncoated lipid droplets in inner regions of skeletal muscle type II fibers associate with type 2 diabetes. Acta Histochem 2022; 124:151869. [PMID: 35220055 DOI: 10.1016/j.acthis.2022.151869] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 02/03/2022] [Accepted: 02/12/2022] [Indexed: 01/02/2023]
Abstract
Skeletal muscle physiology remains of paramount importance in understanding insulin resistance. Due to its high lipid turnover rates, regulation of intramyocellular lipid droplets (LDs) is a key factor. Perilipin 5 (PLIN5) is one of the most critical agents in such regulation, being often referred as a protector against lipotoxicity and consequent skeletal muscle insulin resistance. We examined area fraction, size, subcellular localization and PLIN5 association of LDs in two fiber types of type 2 diabetic (T2D), obese (OB) and healthy (HC) individuals by means of fluorescence microscopy and image analysis. We found that T2D type II fibers have a significant sub-population of large and internalized LDs, uncoated by PLIN5. Based on this novel result, additional hypotheses for the pathophysiology of skeletal muscle insulin resistance are formulated, together with future research directions.
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Affiliation(s)
- Vasco Fachada
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyvaskyla, Rautpohjankatu 8, Jyvaskyla 40014, Finland.
| | - Paavo Rahkila
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyvaskyla, Rautpohjankatu 8, Jyvaskyla 40014, Finland
| | - Nuno Fachada
- Lusofona University, COPELABS, Lisboa 1749-024, Portugal
| | - Tuomas Turpeinen
- Department of Physics, University of Jyvaskyla, Jyvaskyla 40014, Finland
| | - Urho M Kujala
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyvaskyla, Rautpohjankatu 8, Jyvaskyla 40014, Finland
| | - Heikki Kainulainen
- Faculty of Sport and Health Sciences, NeuroMuscular Research Center, University of Jyvaskyla, Rautpohjankatu 8, Jyvaskyla 40014, Finland
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6
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Barrett JS, Whytock KL, Strauss JA, Wagenmakers AJM, Shepherd SO. High intramuscular triglyceride turnover rates and the link to insulin sensitivity: influence of obesity, type 2 diabetes and physical activity. Appl Physiol Nutr Metab 2022; 47:343-356. [PMID: 35061523 DOI: 10.1139/apnm-2021-0631] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Large intramuscular triglyceride (IMTG) stores in sedentary, obese individuals have been linked to insulin resistance, yet well-trained athletes exhibit high IMTG levels whilst maintaining insulin sensitivity. Contrary to previous assumptions, it is now known that IMTG content per se does not result in insulin resistance. Rather, insulin resistance is caused, at least in part, by the presence of high concentrations of harmful lipid metabolites, such as diacylglycerols and ceramides in muscle. Several mechanistic differences between obese sedentary individuals and their highly trained counterparts have been identified, which determine the differential capacity for IMTG synthesis and breakdown in these populations. In this review, we first describe the most up-to-date mechanisms by which a low IMTG turnover rate (both breakdown and synthesis) leads to the accumulation of lipid metabolites and results in skeletal muscle insulin resistance. We then explore current and potential exercise and nutritional strategies that target IMTG turnover in sedentary obese individuals, to improve insulin sensitivity. Overall, improving IMTG turnover should be an important component of successful interventions that aim to prevent the development of insulin resistance in the ever-expanding sedentary, overweight and obese populations. Novelty: A description of the most up-to-date mechanisms regulating turnover of the IMTG pool. An exploration of current and potential exercise/nutritional strategies to target and enhance IMTG turnover in obese individuals. Overall, highlights the importance of improving IMTG turnover to prevent the development of insulin resistance.
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Affiliation(s)
- J S Barrett
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - K L Whytock
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - J A Strauss
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - A J M Wagenmakers
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - S O Shepherd
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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7
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Dubińska-Magiera M, Lewandowski D, Cysewski D, Pawlak S, Najbar B, Daczewska M. Lipid droplets in skeletal muscle during grass snake (Natrix natrix L.) development. Biochim Biophys Acta Mol Cell Biol Lipids 2022; 1867:159086. [PMID: 34822977 DOI: 10.1016/j.bbalip.2021.159086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 10/19/2021] [Accepted: 11/15/2021] [Indexed: 11/21/2022]
Abstract
Lipid droplets (LDs) are common organelles observed in Eucaryota. They are multifunctional organelles (involved in lipid storage, metabolism, and trafficking) that originate from endoplasmic reticulum (ER). LDs consist of a neutral lipid core, made up of diacyl- and triacylglycerols (DAGs and TAGs) and cholesterol esters (CEs), surrounded by a phospholipid monolayer and proteins, which are necessary for their structure and dynamics. Here, we report the protein and lipid composition as well as characterization and dynamics of grass snake (Natrix natrix) skeletal muscle LDs at different developmental stages. In the present study, we used detailed morphometric, LC-MS, quantitative lipidomic analyses of LDs isolated from the skeletal muscles of the snake embryos, immunofluorescence, and TEM. Our study also provides a valuable insight concerning the LDs' multifunctionality and ability to interact with a variety of organelles. These LD features are reflected in their proteome composition, which contains scaffold proteins, metabolic enzymes signalling polypeptides, proteins necessary for the formation of docking sites, and many others. We also provide insights into the biogenesis and growth of muscle LDs goes beyond the conventional mechanism based on the synthesis and incorporation of TAGs and LD fusion. We assume that the formation and functioning of grass snake muscle LDs are based on additional mechanisms that have not yet been identified, which could be related to the unique features of reptiles that are manifested in the after-hatching period of life, such as a reptile-specific strategy for energy saving during hibernation.
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Affiliation(s)
- Magda Dubińska-Magiera
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland
| | - Damian Lewandowski
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland.
| | - Dominik Cysewski
- Mass Spectrometry Laboratory, IBB PAS, Pawinskiego 5a, 02-106 Warsaw, Poland
| | - Seweryn Pawlak
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland
| | - Bartłomiej Najbar
- Faculty of Biological Sciences, University of Zielona Góra, Szafrana 1, 65-516 Zielona Góra 1, Poland
| | - Małgorzata Daczewska
- Department of Animal Developmental Biology, Faculty of Biological Sciences, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland
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Bai Q, Yang C, Yang M, Pei Z, Zhou X, Liu J, Ji H, Li G, Wu M, Qin Y, Wang Q, Wu L. pH-Dominated Selective Imaging of Lipid Droplets and Mitochondria via a Polarity-Reversible Ratiometric Fluorescent Probe. Anal Chem 2022; 94:2901-2911. [DOI: 10.1021/acs.analchem.1c04806] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Qingqing Bai
- Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, P. R. China
| | - Chaojie Yang
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Majun Yang
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Zhaoqing Pei
- Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, P. R. China
| | - Xiaobo Zhou
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Jinxia Liu
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Haiwei Ji
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Guo Li
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Mingmin Wu
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Yuling Qin
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Qi Wang
- Innovative Institute of Chinese Medicine and Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, P. R. China
- School of Public Health, Nantong University, Nantong 226019, P. R. China
| | - Li Wu
- School of Public Health, Nantong University, Nantong 226019, P. R. China
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9
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Tan Y, Jin Y, Zhao P, Wu J, Ren Z. Lipid droplets contribute myogenic differentiation in C2C12 by promoting the remodeling of the acstin-filament. Cell Death Dis 2021; 12:1102. [PMID: 34815388 PMCID: PMC8611090 DOI: 10.1038/s41419-021-04273-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 09/17/2021] [Accepted: 10/04/2021] [Indexed: 12/29/2022]
Abstract
Lipid droplet (LD), a multi-functional organelle, is found in most eukaryotic cells. LDs participate in the regulation of many cellular processes including proliferation, stress, and apoptosis. Previous studies showed the athlete's paradox that trained athletes accumulate LDs in their skeletal muscle. However, the impact of LDs on skeletal muscle and myogenesis is not clear. We discovered that C2C12 myoblast cells containing more LDs formed more multinucleated muscle fibers. We also discovered that LDs promoted cell migration and fusion by promoting actin-filaments remodeling. Mechanistically, two LD-proteins, Acyl-CoA synthetase long chain family member 3 (ACSL3) and lysophosphatidylcholine acyltransferase 1 (LPCAT1), medicated the recruitment of actinin proteins which contributed to actin-filaments formation on the surface of LDs. During remodeling, the actinin proteins on LDs surface translocated to actin-filaments via ARF1/COPI vesicles. Our study demonstrate LDs contribute to cell differentiation, which lead to new insight into the LD function.
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Affiliation(s)
- Yanjie Tan
- grid.35155.370000 0004 1790 4137Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, 430070 Wuhan, Hubei P. R. China ,grid.410585.d0000 0001 0495 1805Institute of Biomedical Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Shandong Normal University, 250014 Jinan, Shandong China
| | - Yi Jin
- grid.35155.370000 0004 1790 4137Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, 430070 Wuhan, Hubei P. R. China
| | - Pengxiang Zhao
- grid.35155.370000 0004 1790 4137Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, 430070 Wuhan, Hubei P. R. China
| | - Jian Wu
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, 430070, Wuhan, Hubei, P. R. China.
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, 430070, Wuhan, Hubei, P. R. China. .,Hubei Hongshan Laboratory, Wuhan, Hubei, China.
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Kovacs M, Geltinger F, Verwanger T, Weiss R, Richter K, Rinnerthaler M. Lipid Droplets Protect Aging Mitochondria and Thus Promote Lifespan in Yeast Cells. Front Cell Dev Biol 2021; 9:774985. [PMID: 34869375 PMCID: PMC8640092 DOI: 10.3389/fcell.2021.774985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/26/2021] [Indexed: 12/20/2022] Open
Abstract
Besides their role as a storage for neutral lipids and sterols, there is increasing evidence that lipid droplets (LDs) are involved in cellular detoxification. LDs are in close contact to a broad variety of organelles where protein- and lipid exchange is mediated. Mitochondria as a main driver of the aging process produce reactive oxygen species (ROS), which damage several cellular components. LDs as highly dynamic organelles mediate a potent detoxification mechanism by taking up toxic lipids and proteins. A stimulation of LDs induced by the simultaneously overexpression of Lro1p and Dga1p (both encoding acyltransferases) prolongs the chronological as well as the replicative lifespan of yeast cells. The increased number of LDs reduces mitochondrial fragmentation as well as mitochondrial ROS production, both phenotypes that are signs of aging. Strains with an altered LD content or morphology as in the sei1∆ or lro1∆ mutant lead to a reduced replicative lifespan. In a yeast strain defective for the LON protease Pim1p, which showed an enhanced ROS production, increased doubling time and an altered mitochondrial morphology, a LRO1 overexpression resulted in a partially reversion of this "premature aging" phenotype.
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Affiliation(s)
| | | | | | | | | | - Mark Rinnerthaler
- Department of Biosciences, Paris-Lodron University Salzburg, Salzburg, Austria
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11
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de Meeûs d'Argenteuil C, Boshuizen B, Vidal Moreno de Vega C, Leybaert L, de Maré L, Goethals K, De Spiegelaere W, Oosterlinck M, Delesalle C. Comparison of Shifts in Skeletal Muscle Plasticity Parameters in Horses in Three Different Muscles, in Answer to 8 Weeks of Harness Training. Front Vet Sci 2021; 8:718866. [PMID: 34733900 PMCID: PMC8558477 DOI: 10.3389/fvets.2021.718866] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 09/07/2021] [Indexed: 12/02/2022] Open
Abstract
Training-induced follow-up of multiple muscle plasticity parameters in postural stability vs. locomotion muscles provides an integrative physiological view on shifts in the muscular metabolic machinery. It can be expected that not all muscle plasticity parameters show the same expression time profile across muscles. This knowledge is important to underpin results of metabolomic studies. Twelve non-competing Standardbred mares were subjected to standardized harness training. Muscle biopsies were taken on a non-training day before and after 8 weeks. Shifts in muscle fiber type composition and muscle fiber cross-sectional area (CSA) were compared in the m. pectoralis, the m. vastus lateralis, and the m. semitendinosus. In the m. vastus lateralis, which showed most pronounced training-induced plasticity, two additional muscle plasticity parameters (capillarization and mitochondrial density) were assessed. In the m. semitendinosus, additionally the mean minimum Feret's diameter was assessed. There was a significant difference in baseline profiles. The m. semitendinosus contained less type I and more type IIX fibers compatible with the most pronounced anaerobic profile. Though no baseline fiber type-specific and overall mean CSA differences could be detected, there was a clear post-training decrease in fiber type specific CSA, most pronounced for the m. vastus lateralis, and this was accompanied by a clear increase in capillary supply. No shifts in mitochondrial density were detected. The m. semitendinosus showed a decrease in fiber type specific CSA of type IIAX fibers and a decrease of type I fiber Feret's diameter as well as mean minimum Feret's diameter. The training-induced increased capillary supply in conjunction with a significant decrease in muscle fiber CSA suggests that the muscular machinery models itself toward an optimal smaller individual muscle fiber structure to receive and process fuels that can be swiftly delivered by the circulatory system. These results are interesting in view of the recently identified important fuel candidates such as branched-chain amino acids, aromatic amino acids, and gut microbiome-related xenobiotics, which need a rapid gut-muscle gateway to reach these fibers and are less challenging for the mitochondrial system. More research is needed with that respect. Results also show important differences between muscle groups with respect to baseline and training-specific modulation.
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Affiliation(s)
- Constance de Meeûs d'Argenteuil
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
| | - Berit Boshuizen
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
- Wolvega Equine Hospital, Oldeholtpade, Netherlands
| | - Carmen Vidal Moreno de Vega
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
| | - Luc Leybaert
- Department of Basic and Applied Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium
| | - Lorie de Maré
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
| | - Klara Goethals
- Department of Veterinary and Biosciences, Faculty of Veterinary Medicine, Research Group Biometrics, Ghent University, Merelbeke, Belgium
| | - Ward De Spiegelaere
- Department of Morphology, Imaging, Orthopedics, Rehabilitation and Nutrition, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Maarten Oosterlinck
- Department of Large Animal Surgery, Anaesthesia and Orthopaedics, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Cathérine Delesalle
- Department of Translational Physiology, Infectiology and Public Health, Research Group of Comparative Physiology, Faculty of Veterinary Medicine, Research Group of Comparative Physiology, Ghent University, Merelbeke, Belgium
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12
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Renne MF, Hariri H. Lipid Droplet-Organelle Contact Sites as Hubs for Fatty Acid Metabolism, Trafficking, and Metabolic Channeling. Front Cell Dev Biol 2021; 9:726261. [PMID: 34595176 PMCID: PMC8477659 DOI: 10.3389/fcell.2021.726261] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/12/2021] [Indexed: 01/21/2023] Open
Abstract
Cells prepare for fluctuations in nutrient availability by storing energy in the form of neutral lipids in organelles called Lipid Droplets (LDs). Upon starvation, fatty acids (FAs) released from LDs are trafficked to different cellular compartments to be utilized for membrane biogenesis or as a source of energy. Despite the biochemical pathways being known in detail, the spatio-temporal regulation of FA synthesis, storage, release, and breakdown is not completely understood. Recent studies suggest that FA trafficking and metabolism are facilitated by inter-organelle contact sites that form between LDs and other cellular compartments such as the Endoplasmic Reticulum (ER), mitochondria, peroxisomes, and lysosomes. LD-LD contact sites are also sites where FAs are transferred in a directional manner to support LD growth and expansion. As the storage site of neutral lipids, LDs play a central role in FA homeostasis. In this mini review, we highlight the role of LD contact sites with other organelles in FA trafficking, channeling, and metabolism and discuss the implications for these pathways on cellular lipid and energy homeostasis.
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Affiliation(s)
- Mike F. Renne
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Hanaa Hariri
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
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13
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Byun KA, Oh S, Son M, Oh SE, Park CH, Son KH, Byun K. Dieckol-Attenuated High-Fat Diet Induced Muscle Atrophy by Modulating Muscular Deposition of Lipid Droplets. Nutrients 2021; 13:3160. [PMID: 34579038 PMCID: PMC8467349 DOI: 10.3390/nu13093160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Revised: 08/31/2021] [Accepted: 09/08/2021] [Indexed: 11/17/2022] Open
Abstract
An excessive fat diet induces intramuscular fat deposition that accumulates as a form of lipid droplet (LD) and leads to lipotoxicity, including muscle atrophy or decreasing muscle strength. Lipotoxicity depends on the number of LDs, subcellular distribution (intermyofibrillar, IMF, LDs or subsarcolemmal, SS), and fiber type-specific differences (type I or type II fiber) as well as the size of LD. Ecklonia cava extracts (ECE), which is known to increase peroxisome proliferator-activated receptor alpha (PPAR-α), which leads to decreasing expression level of perilipin2 (PLIN2). PLIN2 is involved in modulating the size of LDs. This study shows that ECE and dieckol could decrease PLIN2 expression and decrease the size and number of LDs in the muscle of high-fat diet (HF)-fed animals and lead to attenuating muscle atrophy. Expression level of PPAR-α was decreased, and PLIN2 was increased by HF. ECE and dieckol increased PPAR-α expression and decreased PLIN2. The diameter of LDs was increased in high-fat diet condition, and it was decreased by ECE or dieckol treatment. The number of LDs in type II fibers/total LDs was increased by HF and it was decreased by ECE or dieckol. The SS LDs were increased, and IMF LDs were decreased by HF. ECE or dieckol decreased SS LDs and increased IMF LDs. The ECE or dieckol attenuated the upregulation of muscle atrophy-related genes including Murf1, Atrogin-1, and p53 by HF. ECE or dieckol increased the cross-sectional area of the muscle fibers and grip strength, which were decreased by HF. In conclusion, ECE or dieckol decreased the size of LDs and modulated the contribution of LDs to less toxic ones by decreasing PLIN2 expression and thus attenuated muscle atrophy and strength, which were induced by HF.
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Affiliation(s)
- Kyung-A Byun
- Department of Anatomy&Cell Biology, Gachon University College of Medicine, Incheon 21936, Korea; (K.-A.B.); (M.S.)
- Functional Cellular Networks Laboratory, Department of Medicine, Graduate School and Lee Gil Ya Cancer and Diabetes Institute, College of Medicine, Gachon University, Incheon 21999, Korea; (S.O.); (S.E.O.)
| | - Seyeon Oh
- Functional Cellular Networks Laboratory, Department of Medicine, Graduate School and Lee Gil Ya Cancer and Diabetes Institute, College of Medicine, Gachon University, Incheon 21999, Korea; (S.O.); (S.E.O.)
| | - Myeongjoo Son
- Department of Anatomy&Cell Biology, Gachon University College of Medicine, Incheon 21936, Korea; (K.-A.B.); (M.S.)
- Functional Cellular Networks Laboratory, Department of Medicine, Graduate School and Lee Gil Ya Cancer and Diabetes Institute, College of Medicine, Gachon University, Incheon 21999, Korea; (S.O.); (S.E.O.)
| | - Seung Eon Oh
- Functional Cellular Networks Laboratory, Department of Medicine, Graduate School and Lee Gil Ya Cancer and Diabetes Institute, College of Medicine, Gachon University, Incheon 21999, Korea; (S.O.); (S.E.O.)
| | - Chul-Hyun Park
- Department of Thoracic and Cardiovascular Surgery, Gachon University Gil Medical Center, Gachon University, Incheon 21565, Korea;
| | - Kuk Hui Son
- Department of Thoracic and Cardiovascular Surgery, Gachon University Gil Medical Center, Gachon University, Incheon 21565, Korea;
| | - Kyunghee Byun
- Department of Anatomy&Cell Biology, Gachon University College of Medicine, Incheon 21936, Korea; (K.-A.B.); (M.S.)
- Functional Cellular Networks Laboratory, Department of Medicine, Graduate School and Lee Gil Ya Cancer and Diabetes Institute, College of Medicine, Gachon University, Incheon 21999, Korea; (S.O.); (S.E.O.)
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14
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Taatjes DJ, Roth J. In focus in HCB. Histochem Cell Biol 2021; 154:347-354. [PMID: 32984928 DOI: 10.1007/s00418-020-01921-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Douglas J Taatjes
- Department of Pathology and Laboratory Medicine, Larner College of Medicine, University of Vermont, Burlington, VT, 05405, USA.
| | - Jürgen Roth
- University of Zurich, 8091, Zurich, Switzerland
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15
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Maunder E, Bradley HE, Deane CS, Hodgson AB, Jones M, Joanisse S, Turner AM, Breen L, Philp A, Wallis GA. Effects of short-term graded dietary carbohydrate intake on intramuscular and whole body metabolism during moderate-intensity exercise. J Appl Physiol (1985) 2021; 131:376-387. [PMID: 34043470 DOI: 10.1152/japplphysiol.00811.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Altering dietary carbohydrate (CHO) intake modulates fuel utilization during exercise. However, there has been no systematic evaluation of metabolic responses to graded changes in short-term (< 1 wk) dietary CHO intake. Thirteen active men performed interval running exercise combined with isocaloric diets over 3 days before evaluation of metabolic responses to 60-min running at 65% V̇O2max on three occasions. Diets contained lower [LOW, 2.40 ± 0.66 g CHO·kg-1·day-1, 21.3 ± 0.5% of energy intake (EI)], moderate (MOD, 4.98 ± 1.31 g CHO·kg-1·day-1, 46.3 ± 0.7% EI), or higher (HIGH, 6.48 ± 1.56 g CHO·kg-1·day-1, 60.5 ± 1.6% EI) CHO. Preexercise muscle glycogen content was lower in LOW [54.3 ± 26.4 mmol·kg-1 wet weight (ww)] compared with MOD (82.6 ± 18.8 mmol·kg -1 ww) and HIGH (80.4 ± 26.0 mmol·kg-1 ww, P < 0.001; MOD vs. HIGH, P = 0.85). Whole body substrate oxidation, systemic responses, and muscle substrate utilization during exercise indicated increased fat and decreased CHO metabolism in LOW [respiratory exchange ratio (RER): 0.81 ± 0.01] compared with MOD (RER 0.86 ± 0.01, P = 0.0005) and HIGH (RER: 0.88 ± 0.01, P < 0.0001; MOD vs. HIGH, P = 0.14). Higher basal muscle expression of genes encoding proteins implicated in fat utilization was observed in LOW. In conclusion, muscle glycogen availability and subsequent metabolic responses to exercise were resistant to increases in dietary CHO intake from ∼5.0 to ∼6.5 g CHO·kg-1·day-1 (46% to 61% EI), while muscle glycogen, gene expression, and metabolic responses were sensitive to more marked reductions in CHO intake (∼2.4 g CHO·kg-1·day-1, ∼21% EI).NEW & NOTEWORTHY The data presented here suggest that metabolic responses to steady-state aerobic exercise are somewhat resistant to short-term changes in dietary carbohydrate (CHO) intake within the 5-6.5 g CHO·kg-1·day-1 [46-61% energy intake (EI)] range. In contrast, reduction in short-term dietary CHO intake to ∼2.4 g CHO·kg-1·day-1 (21% EI) evoked clear changes indicative of increased fat and decreased CHO metabolism during exercise.
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Affiliation(s)
- Ed Maunder
- Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
| | - Helen E Bradley
- School of Sport, Exercise, and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Colleen S Deane
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.,Living Systems Institute, University of Exeter, Exeter, United Kingdom
| | | | - Michael Jones
- School of Sport, Exercise, and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Sophie Joanisse
- Department of Sport and Exercise Sciences, Manchester Metropolitan University, Manchester, United Kingdom
| | - Alice M Turner
- Institute for Applied Health Research, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom.,University Hospitals Birmingham National Health Services Foundation Trust, Heartlands Hospital, Birmingham, United Kingdom
| | - Leigh Breen
- School of Sport, Exercise, and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Andrew Philp
- Healthy Ageing Research Theme, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia.,St. Vincent's Medical School, University of New South Wales Medicine, University of New South Wales Sydney, Sydney, New South Wales, Australia
| | - Gareth A Wallis
- School of Sport, Exercise, and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
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16
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Choudhary V, Schneiter R. A Unique Junctional Interface at Contact Sites Between the Endoplasmic Reticulum and Lipid Droplets. Front Cell Dev Biol 2021; 9:650186. [PMID: 33898445 PMCID: PMC8060488 DOI: 10.3389/fcell.2021.650186] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/09/2021] [Indexed: 12/19/2022] Open
Abstract
Lipid droplets (LDs) constitute compartments dedicated to the storage of metabolic energy in the form of neutral lipids. LDs originate from the endoplasmic reticulum (ER) with which they maintain close contact throughout their life cycle. These ER-LD junctions facilitate the exchange of both proteins and lipids between these two compartments. In recent years, proteins that are important for the proper formation of LDs and localize to ER-LD junctions have been identified. This junction is unique as it is generally believed to invoke a transition from the ER bilayer membrane to a lipid monolayer that delineates LDs. Proper formation of this junction requires the ordered assembly of proteins and lipids at specialized ER subdomains. Without such a well-ordered assembly of LD biogenesis factors, neutral lipids are synthesized throughout the ER membrane, resulting in the formation of aberrant LDs. Such ectopically formed LDs impact ER and lipid homeostasis, resulting in different types of lipid storage diseases. In response to starvation, the ER-LD junction recruits factors that tether the vacuole to these junctions to facilitate LD degradation. In addition, LDs maintain close contacts with peroxisomes and mitochondria for metabolic channeling of the released fatty acids toward beta-oxidation. In this review, we discuss the function of different components that ensure proper functioning of LD contact sites, their role in lipogenesis and lipolysis, and their relation to lipid storage diseases.
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Affiliation(s)
- Vineet Choudhary
- Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi, India
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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17
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Smolič T, Tavčar P, Horvat A, Černe U, Halužan Vasle A, Tratnjek L, Kreft ME, Scholz N, Matis M, Petan T, Zorec R, Vardjan N. Astrocytes in stress accumulate lipid droplets. Glia 2021; 69:1540-1562. [PMID: 33609060 PMCID: PMC8248329 DOI: 10.1002/glia.23978] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 01/14/2021] [Accepted: 02/01/2021] [Indexed: 02/06/2023]
Abstract
When the brain is in a pathological state, the content of lipid droplets (LDs), the lipid storage organelles, is increased, particularly in glial cells, but rarely in neurons. The biology and mechanisms leading to LD accumulation in astrocytes, glial cells with key homeostatic functions, are poorly understood. We imaged fluorescently labeled LDs by microscopy in isolated and brain tissue rat astrocytes and in glia-like cells in Drosophila brain to determine the (sub)cellular localization, mobility, and content of LDs under various stress conditions characteristic for brain pathologies. LDs exhibited confined mobility proximal to mitochondria and endoplasmic reticulum that was attenuated by metabolic stress and by increased intracellular Ca2+ , likely to enhance the LD-organelle interaction imaged by electron microscopy. When de novo biogenesis of LDs was attenuated by inhibition of DGAT1 and DGAT2 enzymes, the astrocyte cell number was reduced by ~40%, suggesting that in astrocytes LD turnover is important for cell survival and/or proliferative cycle. Exposure to noradrenaline, a brain stress response system neuromodulator, and metabolic and hypoxic stress strongly facilitated LD accumulation in astrocytes. The observed response of stressed astrocytes may be viewed as a support for energy provision, but also to be neuroprotective against the stress-induced lipotoxicity.
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Affiliation(s)
- Tina Smolič
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Petra Tavčar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Anemari Horvat
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Urška Černe
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Ana Halužan Vasle
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Larisa Tratnjek
- Faculty of Medicine, Institute of Cell Biology, University of Ljubljana, Ljubljana, Slovenia
| | - Mateja Erdani Kreft
- Faculty of Medicine, Institute of Cell Biology, University of Ljubljana, Ljubljana, Slovenia
| | - Nicole Scholz
- Division of General Biochemistry, Medical Faculty, Rudolf Schönheimer Institute of Biochemistry, Leipzig University, Leipzig, Germany
| | - Maja Matis
- Medical Faculty, Institute of Cell Biology, University of Münster, Münster, Germany.,Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Toni Petan
- Department of Molecular and Biomedical Sciences, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Laboratory of Cell Engineering, Celica Biomedical, Ljubljana, Slovenia
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18
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Wang L, Liu J, Miao Z, Pan Q, Cao W. Lipid droplets and their interactions with other organelles in liver diseases. Int J Biochem Cell Biol 2021; 133:105937. [PMID: 33529713 DOI: 10.1016/j.biocel.2021.105937] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 12/07/2020] [Accepted: 01/06/2021] [Indexed: 02/01/2023]
Abstract
Lipid droplets are cellular organelles used for lipid storage with a hydrophobic core of neutral lipids enclosed by a phospholipid monolayer. Besides presenting as giant single organelles in fat tissue, lipid droplets are also widely present as a multitude of small structures in hepatocytes, where they play key roles in health and disease of the liver. In addition to lipid storage, lipid droplets are also directly involved in lipid metabolism, membrane biosynthesis, cell signaling, inflammation, pathogen-host interaction and cancer development. In addition, they interact with other cellular organelles to regulate cellular biology. It is fair to say that the exact functions of lipid droplets in cellular physiology remain largely obscure. Thus prompted, here we aim to analyze the corpus of contemporary biomedical literature to create a framework as to how the role of lipid droplets in hepatocyte physiology and pathophysiology should be understood. The resulting framework should help understanding the interaction of lipid droplets with other organelles in important liver diseases, including fatty liver disease, viral hepatitis and liver cancer and direct further research directions.
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Affiliation(s)
- Ling Wang
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands
| | - Jiaye Liu
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands
| | - Zhijiang Miao
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands
| | - Qiuwei Pan
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands.
| | - Wanlu Cao
- Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, the Netherlands.
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19
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Bosch M, Parton RG, Pol A. Lipid droplets, bioenergetic fluxes, and metabolic flexibility. Semin Cell Dev Biol 2020; 108:33-46. [DOI: 10.1016/j.semcdb.2020.02.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 02/13/2020] [Accepted: 02/27/2020] [Indexed: 12/18/2022]
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20
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Seibert JT, Najt CP, Heden TD, Mashek DG, Chow LS. Muscle Lipid Droplets: Cellular Signaling to Exercise Physiology and Beyond. Trends Endocrinol Metab 2020; 31:928-938. [PMID: 32917515 PMCID: PMC7704552 DOI: 10.1016/j.tem.2020.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/09/2020] [Accepted: 08/13/2020] [Indexed: 12/21/2022]
Abstract
Conventionally viewed as energy storage depots, lipid droplets (LDs) play a central role in muscle lipid metabolism and intracellular signaling, as recognized by recent advances in our biological understanding. Specific subpopulations of muscle LDs, defined by location and associated proteins, are responsible for distinct biological functions. In this review, the traditional view of muscle LDs is examined, and the emerging role of LDs in intracellular signaling is highlighted. The effects of chronic and acute exercise on muscle LD metabolism and signaling is discussed. In conclusion, future directions for muscle LD research are identified. The primary focus will be on human studies, with inclusion of select animal/cellular/non-muscle studies as appropriate, to provide the underlying mechanisms driving the observed findings.
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Affiliation(s)
- Jacob T Seibert
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Charles P Najt
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Timothy D Heden
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Douglas G Mashek
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, Minneapolis, MN 55455, USA
| | - Lisa S Chow
- Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, Minneapolis, MN 55455, USA.
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21
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Glancy B, Kim Y, Katti P, Willingham TB. The Functional Impact of Mitochondrial Structure Across Subcellular Scales. Front Physiol 2020; 11:541040. [PMID: 33262702 PMCID: PMC7686514 DOI: 10.3389/fphys.2020.541040] [Citation(s) in RCA: 104] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 10/20/2020] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are key determinants of cellular health. However, the functional role of mitochondria varies from cell to cell depending on the relative demands for energy distribution, metabolite biosynthesis, and/or signaling. In order to support the specific needs of different cell types, mitochondrial functional capacity can be optimized in part by modulating mitochondrial structure across several different spatial scales. Here we discuss the functional implications of altering mitochondrial structure with an emphasis on the physiological trade-offs associated with different mitochondrial configurations. Within a mitochondrion, increasing the amount of cristae in the inner membrane improves capacity for energy conversion and free radical-mediated signaling but may come at the expense of matrix space where enzymes critical for metabolite biosynthesis and signaling reside. Electrically isolating individual cristae could provide a protective mechanism to limit the spread of dysfunction within a mitochondrion but may also slow the response time to an increase in cellular energy demand. For individual mitochondria, those with relatively greater surface areas can facilitate interactions with the cytosol or other organelles but may be more costly to remove through mitophagy due to the need for larger phagophore membranes. At the network scale, a large, stable mitochondrial reticulum can provide a structural pathway for energy distribution and communication across long distances yet also enable rapid spreading of localized dysfunction. Highly dynamic mitochondrial networks allow for frequent content mixing and communication but require constant cellular remodeling to accommodate the movement of mitochondria. The formation of contact sites between mitochondria and several other organelles provides a mechanism for specialized communication and direct content transfer between organelles. However, increasing the number of contact sites between mitochondria and any given organelle reduces the mitochondrial surface area available for contact sites with other organelles as well as for metabolite exchange with cytosol. Though the precise mechanisms guiding the coordinated multi-scale mitochondrial configurations observed in different cell types have yet to be elucidated, it is clear that mitochondrial structure is tailored at every level to optimize mitochondrial function to meet specific cellular demands.
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Affiliation(s)
- Brian Glancy
- Muscle Energetics Laboratory, NHLBI, National Institutes of Health, Bethesda, MD, United States
- NIAMS, National Institutes of Health, Bethesda, MD, United States
| | - Yuho Kim
- Muscle Energetics Laboratory, NHLBI, National Institutes of Health, Bethesda, MD, United States
- Department of Physical Therapy and Kinesiology, University of Massachusetts Lowell, Lowell, MA, United States
| | - Prasanna Katti
- Muscle Energetics Laboratory, NHLBI, National Institutes of Health, Bethesda, MD, United States
| | - T. Bradley Willingham
- Muscle Energetics Laboratory, NHLBI, National Institutes of Health, Bethesda, MD, United States
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22
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Tobias IS, Galpin AJ. Moving human muscle physiology research forward: an evaluation of fiber type-specific protein research methodologies. Am J Physiol Cell Physiol 2020; 319:C858-C876. [DOI: 10.1152/ajpcell.00107.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Human skeletal muscle is a heterogeneous tissue composed of multiple fiber types that express unique contractile and metabolic properties. While analysis of mixed fiber samples predominates and holds value, increasing attention has been directed toward studying proteins segregated by fiber type, a methodological distinction termed “fiber type-specific.” Fiber type-specific protein studies have the advantage of uncovering key molecular effects that are often missed in mixed fiber homogenate studies but also require greater time and resource-intensive methods, particularly when applied to human muscle. This review summarizes and compares current methods used for fiber type-specific protein analysis, highlighting their advantages and disadvantages for human muscle studies, in addition to recent advances in these techniques. These methods can be grouped into three categories based on the initial processing of the tissue: 1) muscle-specific fiber homogenates, 2) cross sections of fiber bundles, and 3) isolated single fibers, with various subtechniques for performing fiber type identification and protein quantification. The relative implementation for each unique methodological approach is analyzed from 83 fiber type-specific studies of proteins in live human muscle found in the literature to date. These studies have investigated several proteins involved in a wide range of cellular functions that are important to muscle tissue. The second half of this review summarizes key findings from this ensemble of fiber type-specific human protein studies. We highlight examples of where this analytical approach has helped to improve understanding of important physiological topics such as insulin sensitivity, muscle hypertrophy, muscle fatigue, and adaptation to different exercise programs.
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Affiliation(s)
- Irene S. Tobias
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
| | - Andrew J. Galpin
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
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23
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Friend or Foe: Lipid Droplets as Organelles for Protein and Lipid Storage in Cellular Stress Response, Aging and Disease. Molecules 2020; 25:molecules25215053. [PMID: 33143278 PMCID: PMC7663626 DOI: 10.3390/molecules25215053] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 02/06/2023] Open
Abstract
Lipid droplets (LDs) were considered as a mere lipid storage organelle for a long time. Recent evidence suggests that LDs are in fact distinct and dynamic organelles with a specialized proteome and functions in many cellular roles. As such, LDs contribute to cellular signaling, protein and lipid homeostasis, metabolic diseases and inflammation. In line with the multitude of functions, LDs interact with many cellular organelles including mitochondria, peroxisomes, lysosomes, the endoplasmic reticulum and the nucleus. LDs are highly mobile and dynamic organelles and impaired motility disrupts the interaction with other organelles. The reduction of interorganelle contacts results in a multitude of pathophysiologies and frequently in neurodegenerative diseases. Contacts not only supply lipids for β-oxidation in mitochondria and peroxisomes, but also may include the transfer of toxic lipids as well as misfolded and harmful proteins to LDs. Furthermore, LDs assist in the removal of protein aggregates when severe proteotoxic stress overwhelms the proteasomal system. During imbalance of cellular lipid homeostasis, LDs also support cellular detoxification. Fine-tuning of LD function is of crucial importance and many diseases are associated with dysfunctional LDs. We summarize the current understanding of LDs and their interactions with organelles, providing a storage site for harmful proteins and lipids during cellular stress, aging inflammation and various disease states.
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24
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Høgild ML, Gudiksen A, Pilegaard H, Stødkilde-Jørgensen H, Pedersen SB, Møller N, Jørgensen JOL, Jessen N. Redundancy in regulation of lipid accumulation in skeletal muscle during prolonged fasting in obese men. Physiol Rep 2020; 7:e14285. [PMID: 31724339 PMCID: PMC6854099 DOI: 10.14814/phy2.14285] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Fasting in human subjects shifts skeletal muscle metabolism toward lipid utilization and accumulation, including intramyocellular lipid (IMCL) deposition. Growth hormone (GH) secretion amplifies during fasting and promotes lipolysis and lipid oxidation, but it is unknown to which degree lipid deposition and metabolism in skeletal muscle during fasting depends on GH action. To test this, we studied nine obese but otherwise healthy men thrice: (a) in the postabsorptive state (“CTRL”), (b) during 72‐hr fasting (“FAST”), and (c) during 72‐hr fasting and treatment with a GH antagonist (GHA) (“FAST + GHA”). IMCL was assessed by magnetic resonance spectroscopy (MRS) and blood samples were drawn for plasma metabolomics assessment while muscle biopsies were obtained for measurements of regulators of substrate metabolism. Prolonged fasting was associated with elevated GH levels and a pronounced GHA‐independent increase in circulating medium‐ and long‐chain fatty acids, glycerol, and ketone bodies indicating increased supply of lipid intermediates to skeletal muscle. Additionally, fasting was associated with a release of short‐, medium‐, and long‐chain acylcarnitines to the circulation from an increased β‐oxidation. This was consistent with a ≈55%–60% decrease in pyruvate dehydrogenase (PDHa) activity. Opposite, IMCL content increased ≈75% with prolonged fasting without an effect of GHA. We suggest that prolonged fasting increases lipid uptake in skeletal muscle and saturates lipid oxidation, both favoring IMCL deposition. This occurs without a detectable effect of GHA on skeletal muscle lipid metabolism.
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Affiliation(s)
- Morten L Høgild
- Medical Research Laboratory, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Anders Gudiksen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Hans Stødkilde-Jørgensen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,The MR Research Center, Aarhus University Hospital, Copenhagen, Denmark
| | - Steen Bønløkke Pedersen
- Medical Research Laboratory, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Niels Møller
- Medical Research Laboratory, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Jens O L Jørgensen
- Medical Research Laboratory, Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Niels Jessen
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Clinical Pharmacology, Aarhus University Hospital, Aarhus, Denmark.,Department of Biomedicine, Aarhus University, Aarhus, Denmark
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25
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Gemmink A, Schrauwen P, Hesselink MKC. Exercising your fat (metabolism) into shape: a muscle-centred view. Diabetologia 2020; 63:1453-1463. [PMID: 32529413 PMCID: PMC7351830 DOI: 10.1007/s00125-020-05170-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 03/23/2020] [Indexed: 12/11/2022]
Abstract
Fatty acids are an important energy source during exercise. Training status and substrate availability are determinants of the relative and absolute contribution of fatty acids and glucose to total energy expenditure. Endurance-trained athletes have a high oxidative capacity, while, in insulin-resistant individuals, fat oxidation is compromised. Fatty acids that are oxidised during exercise originate from the circulation (white adipose tissue lipolysis), as well as from lipolysis of intramyocellular lipid droplets. Moreover, hepatic fat may contribute to fat oxidation during exercise. Nowadays, it is clear that myocellular lipid droplets are dynamic organelles and that number, size, subcellular distribution, lipid droplet coat proteins and mitochondrial tethering of lipid droplets are determinants of fat oxidation during exercise. This review summarises recent insights into exercise-mediated changes in lipid metabolism and insulin sensitivity in relation to lipid droplet characteristics in human liver and muscle. Graphical abstract.
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Affiliation(s)
- Anne Gemmink
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200 MD, Maastricht, the Netherlands
| | - Patrick Schrauwen
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200 MD, Maastricht, the Netherlands
| | - Matthijs K C Hesselink
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200 MD, Maastricht, the Netherlands.
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26
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Jiang G, Jin Y, Li M, Wang H, Xiong M, Zeng W, Yuan H, Liu C, Ren Z, Liu C. Faster and More Specific: Excited-State Intramolecular Proton Transfer-Based Dyes for High-Fidelity Dynamic Imaging of Lipid Droplets within Cells and Tissues. Anal Chem 2020; 92:10342-10349. [PMID: 32615751 DOI: 10.1021/acs.analchem.0c00390] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lipid droplets (LDs), a type of dynamic organelle residing at the center of cellular lipid storage, have been identified to play important roles in multiple biological processes, metabolic disorders, and diseases. The highly dynamic characters of LDs were found to correspond to their physiological and pathological functions. Hence, the fluorescent probes which enable dynamic tracking of LDs should be very helpful for better understanding the mechanisms of LDs involved biological processes and diseases. Herein we present, to the best of our knowledge, the first class of excited-state intramolecular proton transfer (ESIPT) fluorescence dyes (Flp-(11-13, 19)) for dynamic imaging of LDs based on 3-hydroxyflavone (3HF) derivatives. Flp-(11-13, 19) display strong fluorescence from yellow to NIR in lipid but exhibit almost nonfluorescence in aqueous solution. Besides, they also show large Stokes shifts (>150 nm), narrow absorption and emission peaks, and good oil-water separation efficiency, which makes them specifically target and stain LDs with very low background noisy in both living cells and fixed cells. They stain intracellular LDs quite quickly (within 30 s) with very low dosage (as low as 500 nM). Benefitting from these advantages, Flp-(11-13, 19) are applied successfully in tracking the dynamic nature of LDs and accumulation of LDs in both aqueous solution and living cells, 3D imaging of LDs for visualization of their repartition within the cells, and visualizing LDs in tissues of diseases mice models including adipose, skeletal muscle, and fatty liver tissues, underscoring the potential utility of these dyes in both LDs biology research and medical diagnosis of LDs involved diseases.
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Affiliation(s)
- Gangwei Jiang
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Yi Jin
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Man Li
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Huiling Wang
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Mengyao Xiong
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Weili Zeng
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Hong Yuan
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Changlin Liu
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan 430070, P. R. China
| | - Chunrong Liu
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Chemical Biology Center, College of Chemistry, and International Joint Research Center for Intelligent Biosensing Technology and Health, Central China Normal University, Wuhan 430079, P. R. China
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27
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Strauss JA, Shepherd DA, Macey M, Jevons EFP, Shepherd SO. Divergence exists in the subcellular distribution of intramuscular triglyceride in human skeletal muscle dependent on the choice of lipid dye. Histochem Cell Biol 2020; 154:369-382. [PMID: 32627050 PMCID: PMC7532971 DOI: 10.1007/s00418-020-01898-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2020] [Indexed: 01/19/2023]
Abstract
Despite over 50 years of research, a comprehensive understanding of how intramuscular triglyceride (IMTG) is stored in skeletal muscle and its contribution as a fuel during exercise is lacking. Immunohistochemical techniques provide information on IMTG content and lipid droplet (LD) morphology on a fibre type and subcellular-specific basis, and the lipid dye Oil Red O (ORO) is commonly used to achieve this. BODIPY 493/503 (BODIPY) is an alternative lipid dye with lower background staining and narrower emission spectra. Here we provide the first quantitative comparison of BODIPY and ORO for investigating exercise-induced changes in IMTG content and LD morphology on a fibre type and subcellular-specific basis. Estimates of IMTG content were greater when using BODIPY, which was predominantly due to BODIPY detecting a larger number of LDs, compared to ORO. The subcellular distribution of intramuscular lipid was also dependent on the lipid dye used; ORO detects a greater proportion of IMTG in the periphery (5 μm below cell membrane) of the fibre, whereas IMTG content was higher in the central region using BODIPY. In response to 60 min moderate-intensity cycling exercise, IMTG content was reduced in both the peripheral (− 24%) and central region (− 29%) of type I fibres (P < 0.05) using BODIPY, whereas using ORO, IMTG content was only reduced in the peripheral region of type I fibres (− 31%; P < 0.05). As well as highlighting some methodological considerations herein, our investigation demonstrates that important differences exist between BODIPY and ORO for detecting and quantifying IMTG on a fibre type and subcellular-specific basis.
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Affiliation(s)
- Juliette A Strauss
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, L3 3AF, UK.
| | - Daisy A Shepherd
- Clinical Epidemiology and Biostatistics Unit, Murdoch Children's Research Institute, Royal Children's Hospital, Victoria, 3052, Australia.,Department of Paediatrics, The University of Melbourne, Victoria, 3010, Australia
| | - Myfanwy Macey
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Emily F P Jevons
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Sam O Shepherd
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, L3 3AF, UK
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28
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Affiliation(s)
- Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster
- Cells-in-Motion Cluster of Excellence (EXC 1003—CiM), University of Münster
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29
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Whytock KL, Parry SA, Turner MC, Woods RM, James LJ, Ferguson RA, Ståhlman M, Borén J, Strauss JA, Cocks M, Wagenmakers AJM, Hulston CJ, Shepherd SO. A 7‐day high‐fat, high‐calorie diet induces fibre‐specific increases in intramuscular triglyceride and perilipin protein expression in human skeletal muscle. J Physiol 2020; 598:1151-1167. [DOI: 10.1113/jp279129] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/13/2020] [Indexed: 12/24/2022] Open
Affiliation(s)
- K. L. Whytock
- Research Institute of Sport and Exercise Science, Tom Reilly Building LJMU Liverpool L3 3AF UK
| | - S. A. Parry
- School of Sport, Exercise and Health Sciences Loughborough University Loughborough LE11 3TU UK
| | - M. C. Turner
- School of Sport, Exercise and Health Sciences Loughborough University Loughborough LE11 3TU UK
| | - R. M. Woods
- School of Sport, Exercise and Health Sciences Loughborough University Loughborough LE11 3TU UK
| | - L. J. James
- School of Sport, Exercise and Health Sciences Loughborough University Loughborough LE11 3TU UK
| | - R. A. Ferguson
- School of Sport, Exercise and Health Sciences Loughborough University Loughborough LE11 3TU UK
| | - M. Ståhlman
- Wallenberg Laboratory, Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - J. Borén
- Wallenberg Laboratory, Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - J. A. Strauss
- Research Institute of Sport and Exercise Science, Tom Reilly Building LJMU Liverpool L3 3AF UK
| | - M. Cocks
- Research Institute of Sport and Exercise Science, Tom Reilly Building LJMU Liverpool L3 3AF UK
| | - A. J. M. Wagenmakers
- Research Institute of Sport and Exercise Science, Tom Reilly Building LJMU Liverpool L3 3AF UK
| | - C. J. Hulston
- School of Sport, Exercise and Health Sciences Loughborough University Loughborough LE11 3TU UK
| | - S. O. Shepherd
- Research Institute of Sport and Exercise Science, Tom Reilly Building LJMU Liverpool L3 3AF UK
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30
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Geltinger F, Tevini J, Briza P, Geiser A, Bischof J, Richter K, Felder T, Rinnerthaler M. The transfer of specific mitochondrial lipids and proteins to lipid droplets contributes to proteostasis upon stress and aging in the eukaryotic model system Saccharomyces cerevisiae. GeroScience 2019; 42:19-38. [PMID: 31676965 PMCID: PMC7031196 DOI: 10.1007/s11357-019-00103-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 09/11/2019] [Indexed: 01/12/2023] Open
Abstract
Originally Lipid droplets (LDs) were considered as being droplets for lipid storage only. Increasing evidence, however, demonstrates that LDs fulfill a pleiotropy of additional functions. Among them is the modulation of protein as well as lipid homeostasis. Under unfavorable pro-oxidative conditions, proteins can form aggregates which may exceed the overall proteolytic capacity of the proteasome. After stress termination LDs can adjust and support the removal of these aggregates. Additionally, LDs interact with mitochondria, specifically take over certain proteins and thus prevent apoptosis. LDs, which are loaded with these harmful proteins, are subsequently eliminated via lipophagy. Recently it was demonstrated that this autophagic process is a modulator of longevity. LDs do not only eliminate potentially dangerous proteins, but they are also able to prevent lipotoxicity by storing specific lipids. In the present study we used the model organism Saccharomyces cerevisiae to compare the proteome as well as lipidome of mitochondria and LDs under different conditions: replicative aging, stress and apoptosis. In this context we found an accumulation of proteins at LDs, supporting the role of LDs in proteostasis. Additionally, the composition of main lipid classes such as phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, phosphatidylglycerols, triacylglycerols, ceramides, phosphatidic acids and ergosterol of LDs and mitochondria changed during stress conditions and aging.
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Affiliation(s)
- Florian Geltinger
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Julia Tevini
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria
| | - Peter Briza
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Amrito Geiser
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Johannes Bischof
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Klaus Richter
- Department of Biosciences, University of Salzburg, Salzburg, Austria
| | - Thomas Felder
- Department of Laboratory Medicine, Paracelsus Medical University, Salzburg, Austria.
- Obesity Research Unit, Paracelsus Medical University, Salzburg, Austria.
| | - Mark Rinnerthaler
- Department of Biosciences, University of Salzburg, Salzburg, Austria.
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31
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Jayasinghe SU, Tankeu AT, Amati F. Reassessing the Role of Diacylglycerols in Insulin Resistance. Trends Endocrinol Metab 2019; 30:618-635. [PMID: 31375395 DOI: 10.1016/j.tem.2019.06.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 12/15/2022]
Abstract
Skeletal muscle (SM) insulin resistance (IR) plays an important role in the burden of obesity, particularly because it leads to glucose intolerance and type 2 diabetes. Among the mechanisms thought to link IR to obesity is the accumulation, in muscle cells, of different lipid metabolites. Diacylglycerols (DAGs) are subject of particular attention due to reported interactions with the insulin signaling cascade. Given that SM accounts for the majority of insulin-stimulated glucose uptake, this review integrates recent observational and mechanistic works with the sole focus on questioning the role of DAGs in SM IR. Particular attention is given to the subcellular distributions and specific structures of DAGs, highlighting future research directions towards reaching a consensus on the mechanistic role played by DAGs.
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Affiliation(s)
- Sisitha U Jayasinghe
- Aging and Muscle Metabolism Laboratory, Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Aurel T Tankeu
- Aging and Muscle Metabolism Laboratory, Department of Physiology, University of Lausanne, Lausanne, Switzerland
| | - Francesca Amati
- Aging and Muscle Metabolism Laboratory, Department of Physiology, University of Lausanne, Lausanne, Switzerland; Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland; Service of Endocrinology, Diabetology and Metabolism, Department of Medicine, University Hospital and Lausanne University, Lausanne, Switzerland.
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32
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Lipotoxicity, aging, and muscle contractility: does fiber type matter? GeroScience 2019; 41:297-308. [PMID: 31227962 DOI: 10.1007/s11357-019-00077-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 06/05/2019] [Indexed: 12/18/2022] Open
Abstract
Sarcopenia is a universal characteristic of the aging process and is often accompanied by increases in whole-body adiposity. These changes in body composition have important clinical implications, given that loss of muscle and gain of fat mass are both significantly and independently associated with declining physical performance as well as an increased risk for disability, hospitalizations, and mortality in older individuals. This increased fat mass is not exclusively stored in adipose depots but may become deposited in non-adipose tissues, such as skeletal muscle, when the oxidative capacity of the adipose tissue itself is exceeded. The redistributed adipose tissue is thought to exert detrimental local effects on the muscle environment given the close proximity. Thus, sarcopenia observed with aging may be better defined in the context of loss of muscle quality rather than loss of muscle quantity per se. In this perspective, we briefly review the age-related physiological changes in cellularity, secretory profiles, and inflammatory status of adipose tissue which drive lipotoxicity (spillover) of skeletal muscle and then provide evidence of how this may affect specific fiber type contractility. We focus on biological contributors (cellular machinery) to contractility for which there is some evidence of vulnerability to lipid stress distinguishing between fiber types.
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33
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Skeletal Muscle Lipid Droplets and the Athlete's Paradox. Cells 2019; 8:cells8030249. [PMID: 30875966 PMCID: PMC6468652 DOI: 10.3390/cells8030249] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/07/2019] [Accepted: 03/12/2019] [Indexed: 12/17/2022] Open
Abstract
The lipid droplet (LD) is an organelle enveloped by a monolayer phospholipid membrane with a core of neutral lipids, which is conserved from bacteria to humans. The available evidence suggests that the LD is essential to maintaining lipid homeostasis in almost all organisms. As a consequence, LDs also play an important role in pathological metabolic processes involving the ectopic storage of neutral lipids, including type 2 diabetes mellitus (T2DM), atherosclerosis, steatosis, and obesity. The degree of insulin resistance in T2DM patients is positively correlated with the size of skeletal muscle LDs. Aerobic exercise can reduce the occurrence and development of various metabolic diseases. However, trained athletes accumulate lipids in their skeletal muscle, and LD size in their muscle tissue is positively correlated with insulin sensitivity. This phenomenon is called the athlete’s paradox. This review will summarize previous studies on the relationship between LDs in skeletal muscle and metabolic diseases and will discuss the paradox at the level of LDs.
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34
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Koh HCE, Ørtenblad N, Winding KM, Hellsten Y, Mortensen SP, Nielsen J. High-intensity interval, but not endurance, training induces muscle fiber type-specific subsarcolemmal lipid droplet size reduction in type 2 diabetic patients. Am J Physiol Endocrinol Metab 2018; 315:E872-E884. [PMID: 30016151 DOI: 10.1152/ajpendo.00161.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This study compared the effects of moderate-intensity endurance training and high-intensity interval training on fiber type-specific subcellular volumetric content and morphology of lipid droplets and mitochondria in skeletal muscles of type 2 diabetic patients. Sixteen sedentary type 2 diabetic patients (57 ± 7 yr old) were randomized to complete 11 wk of either 40-min cycling at 50% peak workload (Endurance, n = 8) or 10 1-min cycling intervals at 95% peak workload separated by 1 min of recovery (High-Intensity Interval, n = 8), three times per week. Assessments for cardiorespiratory fitness, body composition, glycemic control, together with muscle biopsies were performed before and after the intervention. Morphometric analyses of lipid droplets and mitochondria were conducted in the subcellular fractions of biopsied muscle fibers using quantitative electron microscopy. The training intervention increased cardiorespiratory fitness, lowered fat mass, and improved nonfasting glycemic control ( P < 0.05), with no difference between training modalities. In the subsarcolemmal space, training decreased lipid droplet volume ( P = 0.003), and high-intensity interval, but not endurance, training reduced the size of lipid droplets, specifically in type 2 fibers ( P < 0.001). No training-induced change in intermyofibrillar lipid droplets was observed in both fiber types. Subsarcolemmal mitochondrial volume was increased by high-intensity interval ( P = 0.02), but not endurance, training ( P = 0.79). Along with improvement in glycemic control, low-volume high-intensity interval training is an alternative time-saving training modality that affects subcellular morphology and volumetric content of lipid droplets in skeletal muscle of type 2 diabetic patients.
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Affiliation(s)
- Han-Chow E Koh
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark , Odense , Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark , Odense , Denmark
| | - Kamilla M Winding
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen , Copenhagen , Denmark
| | - Ylva Hellsten
- Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen , Copenhagen , Denmark
| | - Stefan P Mortensen
- Department of Cardiovascular and Renal Research, Faculty of Health Sciences, University of Southern Denmark , Odense , Denmark
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen , Copenhagen , Denmark
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics, Faculty of Health Sciences, University of Southern Denmark , Odense , Denmark
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35
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Sharma A, Jha AK, Mishra S, Jain A, Chauhan BS, Kathuria M, Rawat KS, Gupta NM, Tripathi R, Mitra K, Sachdev M, Bhatt MLB, Goel A. Imaging and Quantitative Detection of Lipid Droplets by Yellow Fluorescent Probes in Liver Sections of Plasmodium Infected Mice and Third Stage Human Cervical Cancer Tissues. Bioconjug Chem 2018; 29:3606-3613. [DOI: 10.1021/acs.bioconjchem.8b00552] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Ashutosh Sharma
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Ajay K. Jha
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Shachi Mishra
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Ankita Jain
- Endocrinology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Bhavana S. Chauhan
- Parasitology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Manoj Kathuria
- Electron Microscopy Unit, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Kundan S. Rawat
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
- Academy of Scientific
and Innovative Research, Ghaziabad 201 002, India
| | - Neeraj M. Gupta
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Renu Tripathi
- Parasitology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Kalyan Mitra
- Electron Microscopy Unit, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Monika Sachdev
- Endocrinology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Madan L. B. Bhatt
- Department of Radiotherapy, King George’s Medical University, Lucknow 226003, India
| | - Atul Goel
- Fluorescent Chemistry Lab, Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
- Academy of Scientific
and Innovative Research, Ghaziabad 201 002, India
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Daemen S, Gemmink A, Brouwers B, Meex RCR, Huntjens PR, Schaart G, Moonen-Kornips E, Jörgensen J, Hoeks J, Schrauwen P, Hesselink MKC. Distinct lipid droplet characteristics and distribution unmask the apparent contradiction of the athlete's paradox. Mol Metab 2018; 17:71-81. [PMID: 30174227 PMCID: PMC6197504 DOI: 10.1016/j.molmet.2018.08.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 08/07/2018] [Accepted: 08/13/2018] [Indexed: 12/18/2022] Open
Abstract
Objective Intramyocellular lipid (IMCL) storage negatively associates with insulin resistance, albeit not in endurance-trained athletes. We investigated the putative contribution of lipid droplet (LD) morphology and subcellular localization to the so-called athlete's paradox. Methods We performed quantitative immunofluorescent confocal imaging of muscle biopsy sections from endurance Trained, Lean sedentary, Obese, and Type 2 diabetes (T2DM) participants (n = 8/group). T2DM patients and Trained individuals were matched for IMCL content. Furthermore we performed this analysis in biopsies of T2DM patients before and after a 12-week exercise program (n = 8). Results We found marked differences in lipid storage morphology between trained subjects and T2DM: the latter group mainly store lipid in larger LDs in the subsarcolemmal (SS) region of type II fibers, whereas Trained store lipid in a higher number of LDs in the intramyofibrillar (IMF) region of type I fibers. In addition, a twelve-week combined endurance and strength exercise program resulted in a LD phenotype shift in T2DM patients partly towards an ‘athlete-like’ phenotype, accompanied by improved insulin sensitivity. Proteins involved in LD turnover were also more abundant in Trained than in T2DM and partly changed in an ‘athlete-like’ fashion in T2DM patients upon exercise training. Conclusions Our findings provide a physiological explanation for the athlete's paradox and reveal LD morphology and distribution as a major determinant of skeletal muscle insulin sensitivity. Distinct lipid droplet morphology and distribution underlies the athletes' paradox. Muscle lipid storage occurs in a fiber type specific manner. Exercise training shifts LD morphology towards an athletes' phenotype.
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Affiliation(s)
- Sabine Daemen
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Anne Gemmink
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Bram Brouwers
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands; Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, FL, USA
| | - Ruth C R Meex
- Department of Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Peter R Huntjens
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Gert Schaart
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Esther Moonen-Kornips
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Johanna Jörgensen
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Joris Hoeks
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Patrick Schrauwen
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands
| | - Matthijs K C Hesselink
- Department of Nutrition and Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, Maastricht, The Netherlands.
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37
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Ripley EM, Clarke GD, Hamidi V, Martinez RA, Settles FD, Solis C, Deng S, Abdul-Ghani M, Tripathy D, DeFronzo RA. Reduced skeletal muscle phosphocreatine concentration in type 2 diabetic patients: a quantitative image-based phosphorus-31 MR spectroscopy study. Am J Physiol Endocrinol Metab 2018; 315:E229-E239. [PMID: 29509433 PMCID: PMC6139498 DOI: 10.1152/ajpendo.00426.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mitochondrial function has been examined in insulin-resistant (IR) states including type 2 diabetes mellitus (T2DM). Previous studies using phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in T2DM reported results as relative concentrations of metabolite ratios, which could obscure differences in phosphocreatine ([PCr]) and adenosine triphosphate concentrations ([ATP]) between T2DM and normal glucose tolerance (NGT) individuals. We used an image-guided 31P-MRS method to quantitate [PCr], inorganic phosphate [Pi], phosphodiester [PDE], and [ATP] in vastus lateralis (VL) muscle in 11 T2DM and 14 NGT subjects. Subjects also received oral glucose tolerance test, euglycemic insulin clamp, 1H-MRS to measure intramyocellular lipids [IMCL], and VL muscle biopsy to evaluate mitochondrial density. T2DM subjects had lower absolute [PCr] and [ATP] than NGT subjects (PCr 28.6 ± 3.2 vs. 24.6 ± 2.4, P < 0.002, and ATP 7.18 ± 0.6 vs. 6.37 ± 1.1, P < 0.02) while [PDE] was higher, but not significantly. [PCr], obtained using the traditional ratio method, showed no significant difference between groups. [PCr] was negatively correlated with HbA1c ( r = -0.63, P < 0.01) and fasting plasma glucose ( r = -0.51, P = 0.01). [PDE] was negatively correlated with Matsuda index ( r = -0.43, P = 0.03) and M/I ( r = -0.46, P = 0.04), but was positively correlated with [IMCL] ( r = 0.64, P < 0.005), HbA1c, and FPG ( r = 0.60, P = 0.001). To summarize, using a modified, in vivo quantitative 31P-MRS method, skeletal muscle [PCr] and [ATP] are reduced in T2DM, while this difference was not observed with the traditional ratio method. The strong inverse correlation between [PCr] vs. HbA1c, FPG, and insulin sensitivity supports the concept that lower baseline skeletal muscle [PCr] is related to key determinants of glucose homeostasis.
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Affiliation(s)
- Erika M Ripley
- Department of Radiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Geoffrey D Clarke
- Department of Radiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
- Research Imaging Institute, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Vala Hamidi
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Robert A Martinez
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Floyd D Settles
- Department of Radiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Carolina Solis
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Shengwen Deng
- Research Imaging Institute, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Muhammad Abdul-Ghani
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Devjit Tripathy
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Ralph A DeFronzo
- Diabetes Division, University of Texas Health Science Center at San Antonio , San Antonio, Texas
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Whytock KL, Shepherd SO, Wagenmakers AJM, Strauss JA. Hormone-sensitive lipase preferentially redistributes to lipid droplets associated with perilipin-5 in human skeletal muscle during moderate-intensity exercise. J Physiol 2018. [PMID: 29527681 DOI: 10.1113/jp275502] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS Hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) are the key enzymes involved in intramuscular triglyceride (IMTG) lipolysis. In isolated rat skeletal muscle, HSL translocates to IMTG-containing lipid droplets (LDs) following electrical stimulation, but whether HSL translocation occurs in human skeletal muscle during moderate-intensity exercise is currently unknown. Perilipin-2 (PLIN2) and perilipin-5 (PLIN5) proteins have been implicated in regulating IMTG lipolysis by interacting with HSL and ATGL in cell culture and rat skeletal muscle studies. This study investigated the hypothesis that HSL (but not ATGL) redistributes to LDs during moderate-intensity exercise in human skeletal muscle, and whether the localisation of these lipases with LDs was affected by the presence of PLIN proteins on the LDs. HSL preferentially redistributed to PLIN5-associated LDs whereas ATGL distribution was not altered with exercise; this is the first study to illustrate the pivotal step of HSL redistribution to PLIN5-associated LDs following moderate-intensity exercise in human skeletal muscle. ABSTRACT Hormone-sensitive lipase (HSL) and adipose triglyceride lipase (ATGL) control skeletal muscle lipolysis. ATGL is present on the surface of lipid droplets (LDs) containing intramuscular triglyceride (IMTG) in both the basal state and during exercise. HSL translocates to LD in ex vivo electrically stimulated rat skeletal muscle. Perilipin-2- and perilipin-5-associated lipid droplets (PLIN2+ and PLIN5+ LDs) are preferentially depleted during exercise in humans, indicating that these PLINs may control muscle lipolysis. We aimed to test the hypothesis that in human skeletal muscle in vivo HSL (but not ATGL) is redistributed to PLIN2+ and PLIN5+ LDs during moderate-intensity exercise. Muscle biopsies from 8 lean trained males (age 21 ± 1 years, BMI 22.6 ± 1.2 kg m-2 and V̇O2 peak 48.2 ± 5.0 ml min-1 kg-1 ) were obtained before and immediately following 60 min of cycling exercise at ∼59% V̇O2 peak . Cryosections were stained using antibodies targeting ATGL, HSL, PLIN2 and PLIN5. LDs were stained using BODIPY 493/503. Images were obtained using confocal immunofluorescence microscopy and object-based colocalisation analyses were performed. Following exercise, HSL colocalisation to LDs increased (P < 0.05), and was significantly greater to PLIN5+ LDs (+53%) than to PLIN5- LDs (+34%) (P < 0.05), while the increases in HSL colocalisation to PLIN2+ LDs (+16%) and PLIN2- LDs (+28%) were not significantly different. Following exercise, the fraction of LDs colocalised with ATGL (0.53 ± 0.04) did not significantly change (P < 0.05) and was not affected by PLIN association to the LDs. This study presents the first evidence of exercise-induced HSL redistribution to LDs in human skeletal muscle and identifies PLIN5 as a facilitator of this mechanism.
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Affiliation(s)
- Katie L Whytock
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Sam O Shepherd
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Anton J M Wagenmakers
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Juliette A Strauss
- Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool L3 3AF, UK
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Daemen S, van Polanen N, Hesselink MKC. The effect of diet and exercise on lipid droplet dynamics in human muscle tissue. ACTA ACUST UNITED AC 2018. [PMID: 29514886 DOI: 10.1242/jeb.167015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The majority of fat in the human body is stored as triacylglycerols in white adipose tissue. In the obese state, adipose tissue mass expands and excess lipids are stored in non-adipose tissues, such as skeletal muscle. Lipids are stored in skeletal muscle in the form of small lipid droplets. Although originally viewed as dull organelles that simply store lipids as a consequence of lipid overflow from adipose tissue, lipid droplets are now recognized as key components in the cell that exert a variety of relevant functions in multiple tissues (including muscle). Here, we review the effect of diet and exercise interventions on myocellular lipid droplets and their putative role in insulin sensitivity from a human perspective. We also provide an overview of lipid droplet biology and identify gaps for future research.
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Affiliation(s)
- Sabine Daemen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Nynke van Polanen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Matthijs K C Hesselink
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
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40
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Auclair N, Melbouci L, St-Pierre D, Levy E. Gastrointestinal factors regulating lipid droplet formation in the intestine. Exp Cell Res 2018; 363:1-14. [PMID: 29305172 DOI: 10.1016/j.yexcr.2017.12.031] [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: 10/23/2017] [Revised: 12/28/2017] [Accepted: 12/29/2017] [Indexed: 12/22/2022]
Abstract
Cytoplasmic lipid droplets (CLD) are considered as neutral lipid reservoirs, which protect cells from lipotoxicity. It became clear that these fascinating dynamic organelles play a role not only in energy storage and metabolism, but also in cellular lipid and protein handling, inter-organelle communication, and signaling among diverse functions. Their dysregulation is associated with multiple disorders, including obesity, liver steatosis and cardiovascular diseases. The central aim of this review is to highlight the link between intra-enterocyte CLD dynamics and the formation of chylomicrons, the main intestinal dietary lipid vehicle, after overviewing the morphology, molecular composition, biogenesis and functions of CLD.
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Affiliation(s)
- N Auclair
- Research Centre, CHU Sainte-Justine and Department of Montreal, Quebec, Canada H3T 1C5; Nutrition, Université de Montréal, Montreal, Quebec, Canada H3T 1C5
| | - L Melbouci
- Research Centre, CHU Sainte-Justine and Department of Montreal, Quebec, Canada H3T 1C5; Department of Sciences and Physical Activities, UQAM, Quebec, Canada H2X 1Y4
| | - D St-Pierre
- Research Centre, CHU Sainte-Justine and Department of Montreal, Quebec, Canada H3T 1C5; Department of Sciences and Physical Activities, UQAM, Quebec, Canada H2X 1Y4
| | - E Levy
- Research Centre, CHU Sainte-Justine and Department of Montreal, Quebec, Canada H3T 1C5; Nutrition, Université de Montréal, Montreal, Quebec, Canada H3T 1C5; Institute of Nutrition and Functional Foods (INAF), Université Laval, Quebec, Quebec, Canada G1V 0A6.
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41
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Yadav PK, Rajasekharan R. The m 6A methyltransferase Ime4 and mitochondrial functions in yeast. Curr Genet 2017; 64:353-357. [PMID: 28975387 DOI: 10.1007/s00294-017-0758-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 09/25/2017] [Accepted: 09/25/2017] [Indexed: 12/21/2022]
Abstract
In eukaryotes, the precise transcriptional and post-transcriptional regulations of gene expression are crucial for the developmental processes. More than 100 types of post-transcriptional RNA modifications have been identified in eukaryotes. The deposition of N6-methyladenosine (m6A) into mRNA is among the most common post-transcriptional RNA modifications known in eukaryotes. It has been reported that m6A RNA modification can regulate gene expression. The role of yeast m6A methyltransferase (Ime4) in meiosis and sporulation in diploid cells is very well proven, but its physiological role in haploid cells has remained unknown until recently. Previously, we have shown that Ime4 epitranscriptionally regulates triacylglycerol (TAG) metabolism and vacuolar morphology in haploid cells. Mitochondrial dysfunction leads to TAG accumulation as lipid droplets (LDs) in the cells; besides, LDs are physically connected to the mitochondria. As of now there are no reports on the role of Ime4 in mitochondrial biology. Here we report the important role played by Ime4 in the mitochondrial morphology and functions in Saccharomyces cerevisiae. The confocal microscopic analysis showed that IME4 gene deletion causes mitochondrial fragmentation; besides, the ime4Δ cells showed a significant decrease in cytochrome c oxidase and citrate synthase activities compared to the wild-type cells. IME4 gene deletion causes mitochondrial dysfunction, and it will be interesting to find out the target genes of Ime4 related to the mitochondrial biology. The determination of the role of Ime4 and its targets in mitochondrial biology could probably help in formulating potential cures for the mitochondria-linked rare genetic disorders.
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Affiliation(s)
- Pradeep Kumar Yadav
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, Karnataka, 570020, India.,Academy of Scientific and Innovative Research, CSIR-CFTRI, Mysore, India
| | - Ram Rajasekharan
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Mysore, Karnataka, 570020, India. .,Academy of Scientific and Innovative Research, CSIR-CFTRI, Mysore, India.
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42
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Barbosa AD, Siniossoglou S. Function of lipid droplet-organelle interactions in lipid homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1459-1468. [DOI: 10.1016/j.bbamcr.2017.04.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/31/2017] [Accepted: 04/02/2017] [Indexed: 12/20/2022]
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Capitanio D, Moriggi M, Gelfi C. Mapping the human skeletal muscle proteome: progress and potential. Expert Rev Proteomics 2017; 14:825-839. [PMID: 28780899 DOI: 10.1080/14789450.2017.1364996] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
INTRODUCTION Human skeletal muscle represents 40% of our body mass and deciphering its proteome composition to further understand mechanisms regulating muscle function under physiological and pathological conditions has proved a challenge. The inter-individual variability, the presence of structurally and functionally different muscle types and the high protein dynamic range require carefully selected methodologies for the assessment of the muscle proteome. Furthermore, physiological studies are understandingly hampered by ethical issues related to biopsies on healthy subjects, making it difficult to recruit matched controls essential for comparative studies. Areas covered: This review critically analyses studies performed on muscle to date and identifies what still remains unknown or poorly investigated in physiological and pathological states, such as training, aging, metabolic disorders and muscular dystrophies. Expert commentary: Efforts should be made on biological fluid analyses targeting low abundant/low molecular weight fragments generated from muscle cell disruption to improve diagnosis and clinical monitoring. From a methodological point of view, particular attention should be paid to improve the characterization of intact proteins and unknown post translational modifications to better understand the molecular mechanisms of muscle disorders.
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Affiliation(s)
- Daniele Capitanio
- a Department of Biomedical Sciences for Health , University of Milan , Segrate , Milan , Italy
| | - Manuela Moriggi
- a Department of Biomedical Sciences for Health , University of Milan , Segrate , Milan , Italy
| | - Cecilia Gelfi
- a Department of Biomedical Sciences for Health , University of Milan , Segrate , Milan , Italy
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Lipid droplet remodelling and reduced muscle ceramides following sprint interval and moderate-intensity continuous exercise training in obese males. Int J Obes (Lond) 2017; 41:1745-1754. [PMID: 28736444 DOI: 10.1038/ijo.2017.170] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 06/16/2017] [Accepted: 07/14/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND/OBJECTIVES In obesity, improved muscle insulin sensitivity following exercise training has been linked to the lowering of diacylglycerol (DAG) and ceramide concentrations. Little is known, however, about how improved insulin action with exercise training in obese individuals relates to lipid droplet (LD) adaptations in skeletal muscle. In this study we investigated the hypothesis that short-term sprint interval training (SIT) and moderate-intensity continuous training (MICT) in obese individuals would increase perilipin (PLIN) expression, increase the proportion of LDs in contact with mitochondria and reduce muscle concentrations of DAGs and ceramides. METHODS Sixteen sedentary obese males performed 4 weeks of either SIT (4-7 × 30 s sprints at 200% Wmax, 3 days week) or MICT (40-60 min cycling at ~65% VO2peak, 5 days per week), and muscle biopsies were obtained pre- and post-training. RESULTS Training increased PLIN2 (SIT 90%, MICT 68%) and PLIN5 (SIT 47%, MICT 34%) expression in type I fibres only, and increased PLIN3 expression in both type I (SIT 63%, MICT 67%) and type II fibres (SIT 70%, MICT 160%) (all P<0.05). Training did not change LD content but increased the proportion of LD in contact with mitochondria (SIT 12%, MICT 21%, P<0.01). Ceramides were reduced following training (SIT -10%, MICT -7%, P<0.05), but DAG was unchanged. No training × group interactions were observed for any variables. CONCLUSIONS These results confirm the hypothesis that SIT and MICT results in remodelling of LDs and lowers ceramide concentrations in skeletal muscle of sedentary obese males.
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Schuldiner M, Bohnert M. A different kind of love - lipid droplet contact sites. Biochim Biophys Acta Mol Cell Biol Lipids 2017. [PMID: 28627434 DOI: 10.1016/j.bbalip.2017.06.005] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Lipid droplets (LDs) store lipids and hence serve as energy reservoir and as a source for building-blocks for the organelle membrane systems. LD biology therefore depends on tight communication with other organelles. The unique architecture of LDs, consisting of a neutral lipid core shielded by a phospholipid-monolayer, is however an obstacle to bulk-exchange of bilayer-bounded vesicles with other organelles. In recent years, it is emerging that contact sites, places where two organelles are positioned in close proximity allowing vesicle-independent communication, are an important way to integrate LDs into the organellar landscape. However, few LD contact sites have been studied in depth and our understanding of their structure, extent and function is only starting to emerge. Here, we highlight recent findings on the functions of LD contact sites and on the proteins involved in their formation and hypothesize about the unique characteristics of the contact sites formed by these intriguing organelles. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.
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Affiliation(s)
- Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Maria Bohnert
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
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Yadav PK, Rajasekharan R. Cardiolipin deficiency causes triacylglycerol accumulation in Saccharomyces cerevisiae. Mol Cell Biochem 2017; 434:89-103. [PMID: 28432553 DOI: 10.1007/s11010-017-3039-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 04/12/2017] [Indexed: 01/05/2023]
Abstract
In yeast, the synthesis of cardiolipin (CL) and phosphatidylethanolamine (PE) occurs mainly in mitochondria. CL and PE have overlapping functions, and they are required for mitochondrial function. PE is physiologically linked with triacylglycerol (TAG) metabolism in Saccharomyces cerevisiae, involving an acyl-CoA-independent pathway through the phospholipid:diacylglycerol acyltransferase activity of the Lro1 protein. There is no report on the physiological link between CL and TAG metabolism. Here we report a metabolic link between CL and TAG accumulation in the S. cerevisiae. Our data indicated that CL deficiency causes TAG accumulation, involving an acyl-CoA-dependent pathway through the diacylglycerol acyltransferase activity of the Dga1 protein with no changes in the TAG molecular species. The DGA1 gene deletion from the CL-deficient strains reduced the TAG levels. Data from in vitro and in vivo analyses showed that CL did not affect the enzymatic activity of Dga1. Our data also showed that CL deficiency leads to the up-regulation of acetyl-CoA synthetase genes (ACS1 and ACS2) of the cytosolic pyruvate dehydrogenase bypass pathway. This study establishes a physiological link between CL and TAG metabolism in S. cerevisiae.
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Affiliation(s)
- Pradeep Kumar Yadav
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Council of Scientific and Industrial Research, Mysore, Karnataka, 570020, India
- Academy of Scientific & Innovative Research, CSIR-CFTRI, Mysore, India
| | - Ram Rajasekharan
- Lipidomic Centre, Department of Lipid Science, CSIR-Central Food Technological Research Institute (CFTRI), Council of Scientific and Industrial Research, Mysore, Karnataka, 570020, India.
- Academy of Scientific & Innovative Research, CSIR-CFTRI, Mysore, India.
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47
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Eisenberg-Bord M, Schuldiner M. Mitochatting - If only we could be a fly on the cell wall. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1469-1480. [PMID: 28433686 DOI: 10.1016/j.bbamcr.2017.04.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 04/12/2017] [Accepted: 04/18/2017] [Indexed: 12/24/2022]
Abstract
Mitochondria, cellular metabolic hubs, perform many essential processes and are required for the production of metabolites such as ATP, iron-sulfur clusters, heme, amino acids and nucleotides. To fulfill their multiple roles, mitochondria must communicate with all other organelles to exchange small molecules, ions and lipids. Since mitochondria are largely excluded from vesicular trafficking routes, they heavily rely on membrane contact sites. Contact sites are areas of close proximity between organelles that allow efficient transfer of molecules, saving the need for slow and untargeted diffusion through the cytosol. More globally, multiple metabolic pathways require coordination between mitochondria and additional organelles and mitochondrial activity affects all other cellular entities and vice versa. Therefore, uncovering the different means of mitochondrial communication will allow us a better understanding of mitochondria and may illuminate disease processes that occur in the absence of proper cross-talk. In this review we focus on how mitochondria interact with all other organelles and emphasize how this communication is essential for mitochondrial and cellular homeostasis. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann.
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Affiliation(s)
- Michal Eisenberg-Bord
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, 7610001 Rehovot, Israel.
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48
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Komiya Y, Sawano S, Mashima D, Ichitsubo R, Nakamura M, Tatsumi R, Ikeuchi Y, Mizunoya W. Mouse soleus (slow) muscle shows greater intramyocellular lipid droplet accumulation than EDL (fast) muscle: fiber type-specific analysis. J Muscle Res Cell Motil 2017; 38:163-173. [PMID: 28281032 DOI: 10.1007/s10974-017-9468-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/16/2017] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is the main tissue of lipid metabolism and accordingly is critical for homeostasis and energy production; however, the determinants of lipid accumulation in skeletal muscle are unknown. Here, we examined whether the soleus muscle (predominantly slow-twitch fibers) has a higher lipid accumulation capacity than that of the extensor digitorum longus (EDL, predominantly fast-twitch fibers) muscle in mice. Soleus and EDL muscles were harvested from male C57BL/6J mice. The mRNA levels of genes involved in fatty acid import and triglyceride synthesis and accumulation were examined in soleus and EDL muscles. The intramyocellular lipid (IMCL) droplets of muscle cross sections and isolated single fibers were visualized by staining with BODIPY493/503, and fiber types were determined by immunofluorescent detection of myosin heavy chain (MyHC) isoforms. We detected higher mRNA expression of genes related to lipid accumulation in the soleus than the EDL. We also observed a marked increase of IMCL in single fibers from the soleus, but not the EDL, after treatment with a high-fat diet plus denervation. Interestingly, greater accumulation of IMCL droplets was observed in type 2A and 2X fibers (MyHC2A- and MyHC2X-positive fibers) than type 1 fibers (MyHC1-positive fibers) in soleus muscles. These results suggest that the soleus contains more IMCL owing to the higher population of type 2A fibers, and the difference in lipid accumulation between the soleus and EDL could depend on fiber type composition.
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Affiliation(s)
- Yusuke Komiya
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
- Department of Animal Science, School of Veterinary Medicine, Kitasato University, Towada, 034-8628, Japan
| | - Shoko Sawano
- Department of Food Nutrition, Fukuoka Women's Junior College, Dazaifu, 818-0193, Japan
| | - Daisuke Mashima
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Riho Ichitsubo
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Mako Nakamura
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Ryuichi Tatsumi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Yoshihide Ikeuchi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan
| | - Wataru Mizunoya
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
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49
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Lee H, Kim SH, Lee JS, Yang YH, Nam JM, Kim BW, Ko YG. Mitochondrial oxidative phosphorylation complexes exist in the sarcolemma of skeletal muscle. BMB Rep 2016; 49:116-21. [PMID: 26645635 PMCID: PMC4915115 DOI: 10.5483/bmbrep.2016.49.2.232] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Indexed: 12/22/2022] Open
Abstract
Although proteomic analyses have revealed the presence of mitochondrial oxidative
phosphorylation (OXPHOS) proteins in the plasma membrane, there have been no
in-depth evaluations of the presence or function of OXPHOS I-V in the plasma
membrane. Here, we demonstrate the in situ localization of
OXPHOS I-V complexes to the sarcolemma of skeletal muscle by immunofluorescence
and immunohistochemistry. A portion of the OXPHOS I-V complex proteins was not
co-stained with MitoTracker but co-localized with caveolin-3 in the sarcolemma
of mouse gastrocnemius. Mitochondrial matrix-facing OXPHOS complex subunits were
ectopically expressed in the sarcolemma of the non-permeabilized muscle fibers
and C2C12 myotubes. The sarcolemmal localization of cytochrome c was also
observed from mouse gastrocnemius muscles and C2C12 myotubes, as determined by
confocal and total internal resonance fluorescence (TIRF) microscopy. Based on
these data, we conclude that a portion of OXPHOS complexes is localized in the
sarcolemma of skeletal muscle and may have non-canonical functions. [BMB Reports
2016; 49(2): 116-121]
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Affiliation(s)
- Hyun Lee
- Division of Life Sciences, Korea University, Seoul 02841, Korea
| | - Seung-Hyeob Kim
- Division of Life Sciences, Korea University, Seoul 02841, Korea
| | - Jae-Seon Lee
- Department of Biomedical Sciences, College of Medicine, Inha University, Incheon 22212, Korea
| | - Yun-Hee Yang
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Jwa-Min Nam
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Bong-Woo Kim
- Division of Life Sciences, Korea University, Seoul 02841, Korea
| | - Young-Gyu Ko
- Division of Life Sciences, Korea University, Seoul 02841, Korea
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50
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Abstract
Lipid droplets are the intracellular sites for neutral lipid storage. They are critical for lipid metabolism and energy homeostasis, and their dysfunction has been linked to many diseases. Accumulating evidence suggests that the roles lipid droplets play in biology are significantly broader than previously anticipated. Lipid droplets are the source of molecules important in the nucleus: they can sequester transcription factors and chromatin components and generate the lipid ligands for certain nuclear receptors. Lipid droplets have also emerged as important nodes for fatty acid trafficking, both inside the cell and between cells. In immunity, new roles for droplets, not directly linked to lipid metabolism, have been uncovered, with evidence that they act as assembly platforms for specific viruses and as reservoirs for proteins that fight intracellular pathogens. Until recently, knowledge about droplets in the nervous system has been minimal, but now there are multiple links between lipid droplets and neurodegeneration: many candidate genes for hereditary spastic paraplegia also have central roles in lipid-droplet formation and maintenance, and mitochondrial dysfunction in neurons can lead to transient accumulation of lipid droplets in neighboring glial cells, an event that may, in turn, contribute to neuronal damage. As the cell biology and biochemistry of lipid droplets become increasingly well understood, the next few years should yield many new mechanistic insights into these novel functions of lipid droplets.
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