1
|
López-Alcalá J, Gordon A, Trávez A, Tercero-Alcázar C, Correa-Sáez A, González-Rellán MJ, Rangel-Zúñiga OA, Rodríguez A, Membrives A, Frühbeck G, Nogueiras R, Calzado MA, Guzmán-Ruiz R, Malagón MM. Localization, traffic and function of Rab34 in adipocyte lipid and endocrine functions. J Biomed Sci 2024; 31:2. [PMID: 38183057 PMCID: PMC10770960 DOI: 10.1186/s12929-023-00990-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 12/20/2023] [Indexed: 01/07/2024] Open
Abstract
BACKGROUND Excessive lipid accumulation in the adipose tissue in obesity alters the endocrine and energy storage functions of adipocytes. Adipocyte lipid droplets represent key organelles coordinating lipid storage and mobilization in these cells. Recently, we identified the small GTPase, Rab34, in the lipid droplet proteome of adipocytes. Herein, we have characterized the distribution, intracellular transport, and potential contribution of this GTPase to adipocyte physiology and its regulation in obesity. METHODS 3T3-L1 and human primary preadipocytes were differentiated in vitro and Rab34 distribution and trafficking were analyzed using markers of cellular compartments. 3T3-L1 adipocytes were transfected with expression vectors and/or Rab34 siRNA and assessed for secretory activity, lipid accumulation and expression of proteins regulating lipid metabolism. Proteomic and protein interaction analyses were employed for the identification of the Rab34 interactome. These studies were combined with functional analysis to unveil the role played by the GTPase in adipocytes, with a focus on the actions conveyed by Rab34 interacting proteins. Finally, Rab34 regulation in response to obesity was also evaluated. RESULTS Our results show that Rab34 localizes at the Golgi apparatus in preadipocytes. During lipid droplet biogenesis, Rab34 translocates from the Golgi to endoplasmic reticulum-related compartments and then reaches the surface of adipocyte lipid droplets. Rab34 exerts distinct functions related to its intracellular location. Thus, at the Golgi, Rab34 regulates cisternae integrity as well as adiponectin trafficking and oligomerization. At the lipid droplets, this GTPase controls lipid accumulation and lipolysis through its interaction with the E1-ubiquitin ligase, UBA1, which induces the ubiquitination and proteasomal degradation of the fatty acid transporter and member of Rab34 interactome, FABP5. Finally, Rab34 levels in the adipose tissue and adipocytes are regulated in response to obesity and related pathogenic insults (i.e., fibrosis). CONCLUSIONS Rab34 plays relevant roles during adipocyte differentiation, including from the regulation of the oligomerization (i.e., biological activity) and secretion of a major adipokine with insulin-sensitizing actions, adiponectin, to lipid storage and mobilization from lipid droplets. Rab34 dysregulation in obesity may contribute to the altered adipokine secretion and lipid metabolism that characterize adipocyte dysfunction in conditions of excess adiposity.
Collapse
Affiliation(s)
- Jaime López-Alcalá
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Ana Gordon
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain.
| | - Andrés Trávez
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Carmen Tercero-Alcázar
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Alejandro Correa-Sáez
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - María Jesús González-Rellán
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - Oriol A Rangel-Zúñiga
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Lipids and Atherosclerosis Unit, IMIBIC/University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Amaia Rodríguez
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Metabolic Research Laboratory, Department of Endocrinology & Nutrition, Clinic, University of Navarra, IdiSNA, Pamplona, Spain
| | - Antonio Membrives
- Department of Medical-Surgical Specialties, University of Córdoba (UCO), Reina Sofia University Hospital (HURS), Córdoba, Spain
| | - Gema Frühbeck
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Metabolic Research Laboratory, Department of Endocrinology & Nutrition, Clinic, University of Navarra, IdiSNA, Pamplona, Spain
| | - Rubén Nogueiras
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
- Department of Physiology, CiMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain
| | - Marco A Calzado
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
| | - Rocío Guzmán-Ruiz
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain
| | - María M Malagón
- Department of Cell Biology, Physiology, and Immunology, Maimonides Institute for Biomedical Research of Córdoba (IMIBIC), University of Córdoba (UCO), Reina Sofía University Hospital (HURS), Córdoba, Spain.
- CIBER Physiopathology of Obesity and Nutrition (CIBERobn), ISCIII, Madrid, Spain.
| |
Collapse
|
2
|
Oshima Y, Haruki T, Koizumi K, Yonezawa S, Taketani A, Kadowaki M, Saito S. Practices, Potential, and Perspectives for Detecting Predisease Using Raman Spectroscopy. Int J Mol Sci 2023; 24:12170. [PMID: 37569541 PMCID: PMC10418989 DOI: 10.3390/ijms241512170] [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: 07/07/2023] [Revised: 07/23/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023] Open
Abstract
Raman spectroscopy shows great potential for practical clinical applications. By analyzing the structure and composition of molecules through real-time, non-destructive measurements of the scattered light from living cells and tissues, it offers valuable insights. The Raman spectral data directly link to the molecular composition of the cells and tissues and provides a "molecular fingerprint" for various disease states. This review focuses on the practical and clinical applications of Raman spectroscopy, especially in the early detection of human diseases. Identifying predisease, which marks the transition from a healthy to a disease state, is crucial for effective interventions to prevent disease onset. Raman spectroscopy can reveal biological processes occurring during the transition states and may eventually detect the molecular dynamics in predisease conditions.
Collapse
Affiliation(s)
- Yusuke Oshima
- Faculty of Engineering, University of Toyama, Toyama 930-8555, Japan
- Research Center for Pre-Disease Science, University of Toyama, Toyama 930-8555, Japan
- Faculty of Medicine, Oita University, Yufu 879-5593, Japan
| | - Takayuki Haruki
- Research Center for Pre-Disease Science, University of Toyama, Toyama 930-8555, Japan
- Faculty of Sustainable Design, University of Toyama, Toyama 930-8555, Japan
| | - Keiichi Koizumi
- Research Center for Pre-Disease Science, University of Toyama, Toyama 930-8555, Japan
- Division of Presymptomatic Disease, Institute of Natural Medicine, University of Toyama, Toyama 930-8555, Japan
| | - Shota Yonezawa
- Research Center for Pre-Disease Science, University of Toyama, Toyama 930-8555, Japan
| | - Akinori Taketani
- Research Center for Pre-Disease Science, University of Toyama, Toyama 930-8555, Japan
| | - Makoto Kadowaki
- Research Center for Pre-Disease Science, University of Toyama, Toyama 930-8555, Japan
| | - Shigeru Saito
- Research Center for Pre-Disease Science, University of Toyama, Toyama 930-8555, Japan
| |
Collapse
|
3
|
Differential Mobilization of the Phospholipid and Triacylglycerol Pools of Arachidonic Acid in Murine Macrophages. Biomolecules 2022; 12:biom12121851. [PMID: 36551279 PMCID: PMC9775050 DOI: 10.3390/biom12121851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/06/2022] [Accepted: 12/09/2022] [Indexed: 12/14/2022] Open
Abstract
Innate immune cells such as monocytes and macrophages contain high levels of arachidonic acid (AA), part of which can be mobilized during cellular activation for the formation of a vast array of bioactive oxygenated metabolites. Monocytes and macrophages present in inflammatory foci typically incorporate large amounts of AA, not only in membrane phospholipids, but also in neutral lipids such as triacylglycerol. Thus, it was of interest to investigate the metabolic fate of these two AA pools in macrophages. Utilizing a variety of radiolabeling techniques to distinguish the phospholipid and triacylglycerol pools, we show in this paper that during an acute stimulation of the macrophages with yeast-derived zymosan, the membrane phospholipid AA pool acts as the major, if not the only, source of releasable AA. On the contrary, the AA pool in triacylglycerol appears to be used at a later stage, when the zymosan-stimulated response has declined, as a source to replenish the phospholipid pools that were consumed during the activation process. Thus, phospholipids and triacylglycerol play different in roles AA metabolism and dynamics during macrophage activation.
Collapse
|
4
|
Pressly JD, Gurumani MZ, Varona Santos JT, Fornoni A, Merscher S, Al-Ali H. Adaptive and maladaptive roles of lipid droplets in health and disease. Am J Physiol Cell Physiol 2022; 322:C468-C481. [PMID: 35108119 PMCID: PMC8917915 DOI: 10.1152/ajpcell.00239.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Advances in the understanding of lipid droplet biology have revealed essential roles for these organelles in mediating proper cellular homeostasis and stress response. Lipid droplets were initially thought to play a passive role in energy storage. However, recent studies demonstrate that they have substantially broader functions, including protection from reactive oxygen species, endoplasmic reticulum stress, and lipotoxicity. Dysregulation of lipid droplet homeostasis is associated with various pathologies spanning neurological, metabolic, cardiovascular, oncological, and renal diseases. This review provides an overview of the current understanding of lipid droplet biology in both health and disease.
Collapse
Affiliation(s)
- Jeffrey D. Pressly
- 1Katz Division of Nephrology and Hypertension and Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, Florida,2Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida
| | - Margaret Z. Gurumani
- 1Katz Division of Nephrology and Hypertension and Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, Florida,2Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida
| | - Javier T. Varona Santos
- 1Katz Division of Nephrology and Hypertension and Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, Florida,2Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida
| | - Alessia Fornoni
- 1Katz Division of Nephrology and Hypertension and Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, Florida,2Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida
| | - Sandra Merscher
- 1Katz Division of Nephrology and Hypertension and Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, Florida,2Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida
| | - Hassan Al-Ali
- 1Katz Division of Nephrology and Hypertension and Katz Family Drug Discovery Center, University of Miami, Miller School of Medicine, Miami, Florida,2Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida,3Department of Neurological Surgery, University of Miami, Miller School of Medicine, Miami, Florida,4The Miami Project to Cure Paralysis, University of Miami, Miller School of Medicine, Miami, Florida,5Sylvester Comprehensive Cancer Center, University of Miami, Miller School of Medicine, Miami, Florida
| |
Collapse
|
5
|
Henderson GC, Hashimoto T, Irving BA, Halliday TM. Editorial: Mechanisms Linking Transport and Utilization of Metabolic Fuels to the Impact of Nutrition and Exercise Upon Health. Front Nutr 2021; 8:803369. [PMID: 34901131 PMCID: PMC8661498 DOI: 10.3389/fnut.2021.803369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/05/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
- Gregory C Henderson
- Department of Nutrition Science, Purdue University, West Lafayette, IN, United States
| | - Takeshi Hashimoto
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Brian A Irving
- Pennington Biomedical Research Center, School of Kinesiology, Louisiana State University, Baton Rouge, LA, United States
| | - Tanya M Halliday
- Department of Health and Kinesiology, University of Utah, Salt Lake City, UT, United States
| |
Collapse
|
6
|
Takei Y, Hirai R, Fukuda A, Miyazaki S, Shimada R, Okamatsu-Ogura Y, Saito M, Leproux P, Hisatake K, Kano H. Visualization of intracellular lipid metabolism in brown adipocytes by time-lapse ultra-multiplex CARS microspectroscopy with an onstage incubator. J Chem Phys 2021; 155:125102. [PMID: 34598561 DOI: 10.1063/5.0063250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We visualized a dynamic process of fatty acid uptake of brown adipocytes using a time-lapse ultra-broadband multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopic imaging system with an onstage incubator. Combined with the deuterium labeling technique, the intracellular uptake of saturated fatty acids was traced up to 9 h, a substantial advance over the initial multiplex CARS system, with an analysis time of 80 min. Characteristic metabolic activities of brown adipocytes, such as resistance to lipid saturation, were elucidated, supporting the utility of the newly developed system.
Collapse
Affiliation(s)
- Yuki Takei
- Department of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
| | - Rie Hirai
- Laboratory of Gene Regulation, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Aya Fukuda
- Laboratory of Gene Regulation, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Shinichi Miyazaki
- Ph.D. Program in Humanics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
| | - Rintaro Shimada
- Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yuko Okamatsu-Ogura
- Laboratory of Biochemistry, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0818, Japan
| | - Masayuki Saito
- Laboratory of Biochemistry, Faculty of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0818, Japan
| | - Philippe Leproux
- Institut de Recherche XLIM, UMR CNRS No. 7252, 123 Avenue Albert Thomas, 87060 Limoges Cedex, France
| | - Koji Hisatake
- Laboratory of Gene Regulation, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan
| | - Hideaki Kano
- Department of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
| |
Collapse
|
7
|
Glucose enhances catecholamine-stimulated lipolysis via increased glycerol-3-phosphate synthesis in 3T3-L1 adipocytes and rat adipose tissue. Mol Biol Rep 2021; 48:6269-6276. [PMID: 34374898 DOI: 10.1007/s11033-021-06617-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 08/02/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND During lipolysis, triglyceride (TG) are hydrolyzed into a glycerol and fatty acids in adipocyte. A significant portion of the fatty acids are re-esterificated into TG, and this is a critical step in promoting lipolysis. Although glycerol-3-phosphate (G3P) is required for triglyceride synthesis in mammalian cell, the substrate for G3P synthesis during active lipolysis is not known. A recent study showed that the inhibition of glucose uptake reduces catecholamine-stimulated lipolysis, suggesting that glucose availability is important in lipolysis in adipocytes. We hypothesized that glucose might play an essential role in generating G3P and thereby promoting catecholamine-stimulated lipolysis in adipocytes. Therefore, we determined the effect of glucose availability on catecholamine-stimulated lipolysis in 3T3-L1 adipocytes and rat adipose tissue. METHODS AND RESULTS 3T3-L1 adipocytes and rat epididymal fat pads were cultured in a medium with/without glucose during stimulation by isoproterenol. Glycerol release was higher when adipocytes were cultured in a glucose-containing medium than that in a medium without glucose. Measurement of glucose uptake during catecholamine-stimulated lipolysis showed a slight, but significant increase in glucose uptake. We also compared glucose metabolism-related protein, such as glucose transporter 4, hexokinase, glycerol-3-phosphate dehydrogenase and lipase contents between fat tissues that play a critical role in active lipolysis. Epididymal fat exhibited higher lipolytic activity than inguinal fat because of higher lipase and glucose metabolism-related protein contents. CONCLUSION We demonstrated that catecholamine-stimulated lipolysis is enhanced in the presence of glucose, and suggests that glucose is one of the primary substrates for G3P in adipocytes during active lipolysis.
Collapse
|
8
|
Rahman MA, Kumar R, Sanchez E, Nazarko TY. Lipid Droplets and Their Autophagic Turnover via the Raft-Like Vacuolar Microdomains. Int J Mol Sci 2021; 22:8144. [PMID: 34360917 PMCID: PMC8348048 DOI: 10.3390/ijms22158144] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 01/01/2023] Open
Abstract
Although once perceived as inert structures that merely serve for lipid storage, lipid droplets (LDs) have proven to be the dynamic organelles that hold many cellular functions. The LDs' basic structure of a hydrophobic core consisting of neutral lipids and enclosed in a phospholipid monolayer allows for quick lipid accessibility for intracellular energy and membrane production. Whereas formed at the peripheral and perinuclear endoplasmic reticulum, LDs are degraded either in the cytosol by lipolysis or in the vacuoles/lysosomes by autophagy. Autophagy is a regulated breakdown of dysfunctional, damaged, or surplus cellular components. The selective autophagy of LDs is called lipophagy. Here, we review LDs and their degradation by lipophagy in yeast, which proceeds via the micrometer-scale raft-like lipid domains in the vacuolar membrane. These vacuolar microdomains form during nutrient deprivation and facilitate internalization of LDs via the vacuolar membrane invagination and scission. The resultant intra-vacuolar autophagic bodies with LDs inside are broken down by vacuolar lipases and proteases. This type of lipophagy is called microlipophagy as it resembles microautophagy, the type of autophagy when substrates are sequestered right at the surface of a lytic compartment. Yeast microlipophagy via the raft-like vacuolar microdomains is a great model system to study the role of lipid domains in microautophagic pathways.
Collapse
Affiliation(s)
- Muhammad Arifur Rahman
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
| | - Ravinder Kumar
- Department of Obstetrics, Gynecology and Reproductive Science, University of California, San Francisco, CA 94143, USA;
| | - Enrique Sanchez
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Taras Y. Nazarko
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; (M.A.R.); (E.S.)
| |
Collapse
|
9
|
Saydmohammed M, Jha A, Mahajan V, Gavlock D, Shun TY, DeBiasio R, Lefever D, Li X, Reese C, Kershaw EE, Yechoor V, Behari J, Soto-Gutierrez A, Vernetti L, Stern A, Gough A, Miedel MT, Lansing Taylor D. Quantifying the progression of non-alcoholic fatty liver disease in human biomimetic liver microphysiology systems with fluorescent protein biosensors. Exp Biol Med (Maywood) 2021; 246:2420-2441. [PMID: 33957803 PMCID: PMC8606957 DOI: 10.1177/15353702211009228] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Metabolic syndrome is a complex disease that involves multiple organ systems including a critical role for the liver. Non-alcoholic fatty liver disease (NAFLD) is a key component of the metabolic syndrome and fatty liver is linked to a range of metabolic dysfunctions that occur in approximately 25% of the population. A panel of experts recently agreed that the acronym, NAFLD, did not properly characterize this heterogeneous disease given the associated metabolic abnormalities such as type 2 diabetes mellitus (T2D), obesity, and hypertension. Therefore, metabolic dysfunction-associated fatty liver disease (MAFLD) has been proposed as the new term to cover the heterogeneity identified in the NAFLD patient population. Although many rodent models of NAFLD/NASH have been developed, they do not recapitulate the full disease spectrum in patients. Therefore, a platform has evolved initially focused on human biomimetic liver microphysiology systems that integrates fluorescent protein biosensors along with other key metrics, the microphysiology systems database, and quantitative systems pharmacology. Quantitative systems pharmacology is being applied to investigate the mechanisms of NAFLD/MAFLD progression to select molecular targets for fluorescent protein biosensors, to integrate computational and experimental methods to predict drugs for repurposing, and to facilitate novel drug development. Fluorescent protein biosensors are critical components of the platform since they enable monitoring of the pathophysiology of disease progression by defining and quantifying the temporal and spatial dynamics of protein functions in the biosensor cells, and serve as minimally invasive biomarkers of the physiological state of the microphysiology system experimental disease models. Here, we summarize the progress in developing human microphysiology system disease models of NAFLD/MAFLD from several laboratories, developing fluorescent protein biosensors to monitor and to measure NAFLD/MAFLD disease progression and implementation of quantitative systems pharmacology with the goal of repurposing drugs and guiding the creation of novel therapeutics.
Collapse
Affiliation(s)
- Manush Saydmohammed
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Anupma Jha
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Vineet Mahajan
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Dillon Gavlock
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Tong Ying Shun
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Richard DeBiasio
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Daniel Lefever
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Xiang Li
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Celeste Reese
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Erin E Kershaw
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Vijay Yechoor
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Jaideep Behari
- Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, Pittsburgh, PA 15261, USA
- UPMC Liver Clinic, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Alejandro Soto-Gutierrez
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Larry Vernetti
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Andrew Stern
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Albert Gough
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Mark T Miedel
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - D Lansing Taylor
- University of Pittsburgh Drug Discovery Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, PA 15261, USA
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| |
Collapse
|
10
|
Konishi S, Hashimoto T, Nakabuchi T, Ozeki T, Kajita H. Cell and tissue system capable of automated culture, stimulation, and monitor with the aim of feedback control of organs-on-a-chip. Sci Rep 2021; 11:2999. [PMID: 33542247 PMCID: PMC7862322 DOI: 10.1038/s41598-020-80447-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/21/2020] [Indexed: 12/25/2022] Open
Abstract
This paper presents progress in the automation of cell and tissue systems and attempts toward the in situ feedback control of organs-on-a-chip. Our study aims to achieve feedback control of a cell and tissue system by a personal computer (PC), whereas most studies on organs-on-a-chip focus on the automation of status monitoring. The implemented system is composed of subsystems including automated culture, stimulation, and monitoring. The monitoring function provides imaging as well as sampling and dispensing in combination with an external analyzer. Individual subsystems can be combined accordingly. First, monitoring of skeletal muscle (SM) and adipose tissues using this system was demonstrated. The highlight of this paper is the application of the system to the feedback control of the lipid droplet (LD) size, where biochemical stimulation using insulin and adrenaline is controlled by a PC according to the obtained LD imaging data. In this study, the system demonstrated its function of maintaining the desired size of LDs. Our results expand the possibility of PC-controllable cell and tissue systems by addressing the challenge of feedback control of organs-on-a-chip. The PC-controllable cell and tissue systems will contribute to living systems-on-a-chip based on homeostasis phenomena involving interactions between organs or tissues.
Collapse
Affiliation(s)
- Satoshi Konishi
- Department of Mechanical Engineering, College of Science and Engineering, Ritsumeikan University, Kusatsu, 525-8577, Japan. .,Graduate Course of Science and Engineering, Ritsumeikan University, Kusatsu, 525-8577, Japan. .,Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, Kusatsu, 525-8577, Japan.
| | - Takeshi Hashimoto
- Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, Kusatsu, 525-8577, Japan.,College of Sport and Health Science, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Tsubasa Nakabuchi
- Graduate Course of Science and Engineering, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Takatoshi Ozeki
- Graduate Course of Science and Engineering, Ritsumeikan University, Kusatsu, 525-8577, Japan
| | - Hiroki Kajita
- Graduate Course of Science and Engineering, Ritsumeikan University, Kusatsu, 525-8577, Japan
| |
Collapse
|
11
|
Morén B, Fryklund C, Stenkula K. Surface-associated lipid droplets: an intermediate site for lipid transport in human adipocytes? Adipocyte 2020; 9:636-648. [PMID: 33108251 PMCID: PMC7595579 DOI: 10.1080/21623945.2020.1838684] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Adipose tissue plays a major role in regulating whole-body energy metabolism. While the biochemical processes regulating storage and release of excess energy are well known, the temporal organization of these events is much less defined. In this study, we have characterized the presence of small surface-associated lipid droplets, distinct from the central droplet, in primary human adipocytes. Based on microscopy analyses, we illustrate the distribution of mitochondria, endoplasmic reticulum and lysosomes in the vicinity of these specialized lipid droplets. Ultrastructure analysis confirmed the presence of small droplets in intact adipose tissue. Further, CIDEC, known to bind and regulate lipid droplet expansion, clearly localized at these lipid droplets. Neither acute or prolonged stimulation with insulin or isoprenaline, or pharmacologic intervention to suppress lipid flux, affected the presence of these lipid droplets. Still, phosphorylated perilipin and hormone-sensitive lipase accumulated at these droplets following adrenergic stimuli, which supports metabolic activity at these locations. Altogether, we propose these lipid droplet clusters represent an intermediate site involved in lipid transport in primary adipocytes.
Collapse
Affiliation(s)
- Björn Morén
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Claes Fryklund
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Karin Stenkula
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| |
Collapse
|
12
|
Hashimoto T, Okada Y, Yamanaka A, Ono N, Uryu K, Maru I. The effect of eleutherococcus senticosus on metabolism-associated protein expression in 3T3-L1 and C2C12 cells. Phys Act Nutr 2020; 24:13-18. [PMID: 33108713 PMCID: PMC7669464 DOI: 10.20463/pan.2020.0016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 09/16/2020] [Indexed: 12/06/2022] Open
Abstract
[Purpose] In vivo studies have demonstrated the ergogenic benefits of eleutherococcus senticosus (ES) supplementation. ES has been observed to enhance endurance capacity, improve cardiovascular function, and alter metabolic functions (e.g., increased fat utilization); however, the exact mechanisms involved remain unknown. We aimed to determine whether ES could effectively induce fat loss and improve muscle metabolic profiles through increases in lipolysis- and lipid metabolism-associated protein expression in 3T3-L1 adipocytes and C2C12 skeletal muscle cells, respectively, to uncover the direct effects of ES on adipocytes and skeletal muscle cells. [Methods] Different doses of ES extracts (0.2, 0.5, and 1.0 mg/mL) were added to cells (0.2 ES, 0.5 ES, and 1.0 ES, respectively) for 72 h and compared to the vehicle control (control). [Results] The intracellular triacylglycerol (TG) content significantly decreased (p < 0.05 for 0.2 ES, p < 0.01 for 0.5 ES and 1.0 ES) in 3T3-L1 cells. Adipose triglyceride lipase, which is involved in active lipolysis, was significantly higher in the 1.0 ES group than in the control group (p < 0.01) of 3T3-L1 adipocytes. In C2C12 cells, the mitochondrial protein voltage-dependent anion channel (VDAC) was significantly increased in the 1.0 ES group (p < 0.01). Furthermore, we found that 1.0 ES activated both 5' AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) in skeletal muscle cells (p < 0.01). [Conclusion] These findings suggest that ES extracts decreased TG content, presumably by increasing lipase in adipocytes and metabolism-associated protein expression as well as mitochondrial biogenesis in muscle cells. These effects may corroborate previous in vivo findings regarding the ergogenic effects of ES supplementation.
Collapse
Affiliation(s)
- Takeshi Hashimoto
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Yoko Okada
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | | | | | - Keisuke Uryu
- Bizen Chemical Co., Ltd., Akaiwa, Okayama, Japan
| | - Isafumi Maru
- Bizen Chemical Co., Ltd., Akaiwa, Okayama, Japan
| |
Collapse
|
13
|
Kato H, Ogasawara J, Takakura H, Shirato K, Sakurai T, Kizaki T, Izawa T. Exercise Training-Enhanced Lipolytic Potency to Catecholamine Depends on the Time of the Day. Int J Mol Sci 2020; 21:ijms21186920. [PMID: 32967199 PMCID: PMC7554872 DOI: 10.3390/ijms21186920] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/16/2020] [Accepted: 09/19/2020] [Indexed: 12/22/2022] Open
Abstract
Exercise training is well known to enhance adipocyte lipolysis in response to hormone challenge. However, the existence of a relationship between the timing of exercise training and its effect on adipocyte lipolysis is unknown. To clarify this issue, Wistar rats were run on a treadmill for 9 weeks in either the early part (E-EX) or late part of the active phase (L-EX). L-EX rats exhibited greater isoproterenol-stimulated lipolysis expressed as fold induction over basal lipolysis, with greater protein expression levels of hormone-sensitive lipase (HSL) phosphorylated at Ser 660 compared to E-EX rats. Furthermore, we discovered that Brain and muscle Arnt-like (BMAL)1 protein can associate directly with several protein kinase A (PKA) regulatory units (RIα, RIβ, and RIIβ) of protein kinase, its anchoring protein (AKAP)150, and HSL, and that the association of BMAL1 with the regulatory subunits of PKA, AKAP150, and HSL was greater in L-EX than in E-EX rats. In contrast, comparison between E-EX and their counterpart sedentary control rats showed a greater co-immunoprecipitation only between BMAL1 and ATGL. Thus, both E-EX and L-EX showed an enhanced lipolytic response to isoproterenol, but the mechanisms underlying exercise training-enhanced lipolytic response to isoproterenol were different in each group.
Collapse
Affiliation(s)
- Hisashi Kato
- Organization for Research Initiatives and Development, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe City, Kyoto 610-0394, Japan;
- Faculty of Health and Sports Science, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe City, Kyoto 610-0394, Japan;
| | - Junetsu Ogasawara
- Department of Health Science, Asahikawa Medical University, 2-1-1-1 Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan;
| | - Hisashi Takakura
- Faculty of Health and Sports Science, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe City, Kyoto 610-0394, Japan;
| | - Ken Shirato
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University of School Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan; (K.S.); (T.S.); (T.K.)
| | - Takuya Sakurai
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University of School Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan; (K.S.); (T.S.); (T.K.)
| | - Takako Kizaki
- Department of Molecular Predictive Medicine and Sport Science, Kyorin University of School Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan; (K.S.); (T.S.); (T.K.)
| | - Tetsuya Izawa
- Faculty of Health and Sports Science, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe City, Kyoto 610-0394, Japan;
- Graduate School of Health and Sports Science, Doshisha University, 1-3 Tatara-Miyakodani, Kyotanabe City, Kyoto 610-0394, Japan
- Correspondence: ; Tel.: +81-424-65-6721; Fax: +81-424-65-6729
| |
Collapse
|
14
|
Pawlak P, Malyszka N, Szczerbal I, Kolodziejski P. Fatty acid induced lipolysis influences embryo development, gene expression and lipid droplet formation in the porcine cumulus cells†. Biol Reprod 2020; 103:36-48. [PMID: 32318713 PMCID: PMC7313259 DOI: 10.1093/biolre/ioaa045] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/25/2020] [Accepted: 03/30/2020] [Indexed: 02/06/2023] Open
Abstract
The pig oocyte maturation protocol differs from other mammalian species due to dependence on follicular fluid (FF) supplementation. One of the most abundant components of the porcine follicular fluid are fatty acids (FAs). Although evidence from other mammalian models revealed a negative impact of saturated fatty acids (SFA) on developmental competence of oocytes, pig has not yet been widely analyzed. Therefore, we aimed to investigate whether supplementation of IVM medium with 150 μM of stearic acid (SA) and oleic acid (OA) affects lipid content and expression of genes related to fatty acid metabolism in porcine cumulus–oocyte complexes and parthenogenetic embryo development. We found significant influence of fatty acids on lipid metabolism in cumulus cells without affecting the oocyte proper. The expression of ACACA, SCD, PLIN2, FADS1, and FADS2 genes was upregulated (P < 0.01) in cumulus cells, while their expression in oocytes did not change. The increase in gene expression was more pronounced in the case of OA (e.g., up to 30-fold increase in PLIN2 transcript level compared to the control). The number of lipid droplets and occupied area increased significantly in the cumulus cells and did not change in oocytes after SA treatment. Oleic acid improved the blastocyst rate (48 vs 32% in control), whereas stearic acid did not affect this parameter (27%). Additionally, we have discovered a phenotypic diversity of LD in cumulus cells in response to FA supplementation, suggesting extensive lipolysis in response to SA. Stearic acid excess in maturation media led to the formation of multiple micro lipid droplets in cumulus cells.
Collapse
Affiliation(s)
- Piotr Pawlak
- Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Poznan, Poland
| | - Natalia Malyszka
- Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Poznan, Poland
| | - Izabela Szczerbal
- Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Poznan, Poland
| | - Pawel Kolodziejski
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
| |
Collapse
|
15
|
Marini G, Nüske E, Leng W, Alberti S, Pigino G. Reorganization of budding yeast cytoplasm upon energy depletion. Mol Biol Cell 2020; 31:1232-1245. [PMID: 32293990 PMCID: PMC7353153 DOI: 10.1091/mbc.e20-02-0125] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Yeast cells, when exposed to stress, can enter a protective state in which cell division, growth, and metabolism are down-regulated. They remain viable in this state until nutrients become available again. How cells enter this protective survival state and what happens at a cellular and subcellular level are largely unknown. In this study, we used electron tomography to investigate stress-induced ultrastructural changes in the cytoplasm of yeast cells. After ATP depletion, we observed significant cytosolic compaction and extensive cytoplasmic reorganization, as well as the emergence of distinct membrane-bound and membraneless organelles. Using correlative light and electron microscopy, we further demonstrated that one of these membraneless organelles was generated by the reversible polymerization of eukaryotic translation initiation factor 2B, an essential enzyme in the initiation of protein synthesis, into large bundles of filaments. The changes we observe are part of a stress-induced survival strategy, allowing yeast cells to save energy, protect proteins from degradation, and inhibit protein functionality by forming assemblies of proteins.
Collapse
Affiliation(s)
- Guendalina Marini
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Elisabeth Nüske
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Weihua Leng
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Simon Alberti
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
| |
Collapse
|
16
|
Yoshikawa M, Hosokawa M, Miyashita K, Fujita T, Nishino H, Hashimoto T. Fucoxanthinol attenuates oxidative stress-induced atrophy and loss in myotubes and reduces the triacylglycerol content in mature adipocytes. Mol Biol Rep 2020; 47:2703-2711. [PMID: 32180086 DOI: 10.1007/s11033-020-05369-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 03/04/2020] [Indexed: 02/06/2023]
Abstract
The combination of sarcopenia and obesity (i.e., sarcopenic obesity) is more strongly associated with disability and metabolic/cardiovascular diseases than obesity or sarcopenia alone. Therefore, countermeasures that simultaneously suppress fat gain and muscle atrophy to prevent an increase in sarcopenic obesity are warranted. The aim of this study was to investigate the simultaneous effects of fucoxanthinol (FXOH) on fat loss in mature adipocytes and the inhibition of atrophy and loss in myotubes induced by oxidative stress. C2C12 myotubes were treated with FXOH for 24 h and further incubated with hydrogen peroxide (H2O2) for 24 h. The area of myosin heavy chain-positive myotubes and the ROS concentration were measured. Mature 3T3-L1 adipocytes were treated with FXOH for 72 h. The triacylglycerol (TG) content and glycerol and fatty acid (FA) release were biochemically measured. The myotube area was smaller in H2O2-treated cells than that in control cells. However, FXOH protected against the H2O2-induced decreases in myotube area. Further, the ROS concentration was significantly higher in the FXOH-treated cells compared with that in the control cells, although it was significantly lower than that in the H2O2-treated cells. On the other hand, in the mature adipocytes, the TG content was significantly decreased by FXOH treatment compared to that in the control. Moreover, FXOH treatment significantly increased glycerol and FA release compared with that of the control. These results suggest that FXOH inhibits H2O2-induced atrophy and loss in myotubes and activates lipolysis and decreases the TG content in mature adipocytes. Accordingly, FXOH has the potential to exert anti-sarcopenic obesity effects.
Collapse
Affiliation(s)
- Maki Yoshikawa
- Faculty of Sport and Health Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Masashi Hosokawa
- Faculty of Fisheries Sciences, Hokkaido University, Hokkaido, Japan
| | - Kazuo Miyashita
- Faculty of Fisheries Sciences, Hokkaido University, Hokkaido, Japan
| | - Takashi Fujita
- Faculty of Pharmaceutical Sciences, Ritsumeikan University, Shiga, Japan
| | | | - Takeshi Hashimoto
- Faculty of Sport and Health Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
| |
Collapse
|
17
|
Spatiotemporal contact between peroxisomes and lipid droplets regulates fasting-induced lipolysis via PEX5. Nat Commun 2020; 11:578. [PMID: 31996685 PMCID: PMC6989686 DOI: 10.1038/s41467-019-14176-0] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 12/17/2019] [Indexed: 01/05/2023] Open
Abstract
Lipid droplets (LDs) are key subcellular organelles for regulating lipid metabolism. Although several subcellular organelles participate in lipid metabolism, it remains elusive whether physical contacts between subcellular organelles and LDs might be involved in lipolysis upon nutritional deprivation. Here, we demonstrate that peroxisomes and peroxisomal protein PEX5 mediate fasting-induced lipolysis by stimulating adipose triglyceride lipase (ATGL) translocation onto LDs. During fasting, physical contacts between peroxisomes and LDs are increased by KIFC3-dependent movement of peroxisomes toward LDs, which facilitates spatial translocations of ATGL onto LDs. In addition, PEX5 could escort ATGL to contact points between peroxisomes and LDs in the presence of fasting cues. Moreover, in adipocyte-specific PEX5-knockout mice, the recruitment of ATGL onto LDs was defective and fasting-induced lipolysis is attenuated. Collectively, these data suggest that physical contacts between peroxisomes and LDs are required for spatiotemporal translocation of ATGL, which is escorted by PEX5 upon fasting, to maintain energy homeostasis. Lipid droplets are organelles that regulate lipid metabolism but if organellar contacts play a role during lipolysis is unclear. Here, the authors show that peroxisomes and peroxisomal protein PEX5 play pivotal roles in the spatial and temporal regulation of fasting-induced lipolysis by translocating ATGL onto lipid droplets
Collapse
|
18
|
Higashida K, Takeuchi N, Inoue S, Hashimoto T, Nakai N. Iron deficiency attenuates catecholamine‑stimulated lipolysis via downregulation of lipolysis‑related proteins and glucose utilization in 3T3‑L1 adipocytes. Mol Med Rep 2020; 21:1383-1389. [PMID: 32016466 DOI: 10.3892/mmr.2020.10929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 10/29/2019] [Indexed: 11/06/2022] Open
Abstract
Iron deficiency has been associated with obesity and related metabolic disorders. The aim of the present study was to evaluate the effect of iron deficiency on fat metabolism, particularly regarding the lipolytic activity, lipolysis‑related protein expression, and glucose utilization of adipocytes. Differentiated 3T3‑L1 adipocytes were incubated with an iron chelator, deferoxamine mesylate (DFO), for 48 h. Subsequently, basal and isoproterenol‑stimulated lipolytic activities, the proteins involved in lipolysis and glucose utilization were compared with a control (CON). The results revealed that treatment with DFO significantly decreased the free iron content but did not affect total protein and lipid contents in adipocytes. Iron deprivation caused a significant reduction in isoproterenol‑stimulated lipolysis, but not basal lipolysis. Lipolysis‑related proteins, including perilipin A, adipose triglyceride lipase, hormone sensitive lipase and comparative gene identification‑58, were decreased in the DFO compared with the CON group. Furthermore, glucose utilization, a major precursor of 3‑glycerol phosphate for micro‑lipid droplet synthesis during lipolysis and the expression of glucose transporter (GLUT) 4 were significantly lower in the DFO group when compared with the CON group. However, hypoxia‑inducible factor‑1α and GLUT1 expressions were upregulated in DFO‑treated adipocytes. In conclusion, the results indicated that low iron availability attenuated catecholamine‑stimulated lipolysis by downregulating lipolytic enzymes and glucose utilization in 3T3‑L1 adipocytes.
Collapse
Affiliation(s)
- Kazuhiko Higashida
- Department of Nutrition, Laboratory of Exercise Nutrition, University of Shiga Prefecture, Hikone, Shiga 522‑8533, Japan
| | - Nodoka Takeuchi
- Department of Nutrition, Laboratory of Exercise Nutrition, University of Shiga Prefecture, Hikone, Shiga 522‑8533, Japan
| | - Sachika Inoue
- Department of Nutrition, Laboratory of Exercise Nutrition, University of Shiga Prefecture, Hikone, Shiga 522‑8533, Japan
| | - Takeshi Hashimoto
- Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga 525‑8577, Japan
| | - Naoya Nakai
- Department of Nutrition, Laboratory of Exercise Nutrition, University of Shiga Prefecture, Hikone, Shiga 522‑8533, Japan
| |
Collapse
|
19
|
Yang Y, Fu M, Li MD, Zhang K, Zhang B, Wang S, Liu Y, Ni W, Ong Q, Mi J, Yang X. O-GlcNAc transferase inhibits visceral fat lipolysis and promotes diet-induced obesity. Nat Commun 2020; 11:181. [PMID: 31924761 PMCID: PMC6954210 DOI: 10.1038/s41467-019-13914-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 11/14/2019] [Indexed: 01/01/2023] Open
Abstract
Excessive visceral fat accumulation is a primary risk factor for metabolically unhealthy obesity and related diseases. The visceral fat is highly susceptible to the availability of external nutrients. Nutrient flux into the hexosamine biosynthetic pathway leads to protein posttranslational modification by O-linked β-N-acetylglucosamine (O-GlcNAc) moieties. O-GlcNAc transferase (OGT) is responsible for the addition of GlcNAc moieties to target proteins. Here, we report that inducible deletion of adipose OGT causes a rapid visceral fat loss by specifically promoting lipolysis in visceral fat. Mechanistically, visceral fat maintains a high level of O-GlcNAcylation during fasting. Loss of OGT decreases O-GlcNAcylation of lipid droplet-associated perilipin 1 (PLIN1), which leads to elevated PLIN1 phosphorylation and enhanced lipolysis. Moreover, adipose OGT overexpression inhibits lipolysis and promotes diet-induced obesity. These findings establish an essential role for OGT in adipose tissue homeostasis and indicate a unique potential for targeting O-GlcNAc signaling in the treatment of obesity.
Collapse
Affiliation(s)
- Yunfan Yang
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Minnie Fu
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Min-Dian Li
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Kaisi Zhang
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Bichen Zhang
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Simeng Wang
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Yuyang Liu
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Weiming Ni
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Qunxiang Ong
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Jia Mi
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Xiaoyong Yang
- Program in Integrative Cell Signaling and Neurobiology of Metabolism, Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, 06510, USA.
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, 06510, USA.
| |
Collapse
|
20
|
Guijas C, Bermúdez MA, Meana C, Astudillo AM, Pereira L, Fernández-Caballero L, Balboa MA, Balsinde J. Neutral Lipids Are Not a Source of Arachidonic Acid for Lipid Mediator Signaling in Human Foamy Monocytes. Cells 2019; 8:cells8080941. [PMID: 31434356 PMCID: PMC6721759 DOI: 10.3390/cells8080941] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 08/16/2019] [Accepted: 08/18/2019] [Indexed: 12/13/2022] Open
Abstract
Human monocytes exposed to free arachidonic acid (AA), a secretory product of endothelial cells, acquire a foamy phenotype which is due to the accumulation of cytoplasmic lipid droplets with high AA content. Recruitment of foamy monocytes to the inflamed endothelium contributes to the development of atherosclerotic lesions. In this work, we investigated the potential role of AA stored in the neutral lipids of foamy monocytes to be cleaved by lipases and contribute to lipid mediator signaling. To this end, we used mass spectrometry-based lipidomic approaches combined with strategies to generate monocytes with different concentrations of AA. Results from our experiments indicate that the phospholipid AA pool in monocytes is stable and does not change upon exposure of the cells to the external AA. On the contrary, the AA pool in triacylglycerol is expandable and can accommodate relatively large amounts of fatty acid. Stimulation of the cells with opsonized zymosan results in the expected decreases of cellular AA. Under all conditions examined, all of the AA decreases observed in stimulated cells were accounted for by decreases in the phospholipid pool; we failed to detect any contribution of the triacylglycerol pool to the response. Experiments utilizing selective inhibitors of phospholipid or triacylglyerol hydrolysis confirmed that the phospholipid pool is the sole contributor of the AA liberated by stimulated cells. Thus, the AA in the triacylglycerol is not a source of free AA for the lipid mediator signaling during stimulation of human foamy monocytes and may be used for other cellular functions.
Collapse
Affiliation(s)
- Carlos Guijas
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Miguel A Bermúdez
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - Clara Meana
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Alma M Astudillo
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Laura Pereira
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - Lidia Fernández-Caballero
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - María A Balboa
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Jesús Balsinde
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain.
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain.
| |
Collapse
|
21
|
Lita A, Kuzmin AN, Pliss A, Baev A, Rzhevskii A, Gilbert MR, Larion M, Prasad PN. Toward Single-Organelle Lipidomics in Live Cells. Anal Chem 2019; 91:11380-11387. [PMID: 31381322 DOI: 10.1021/acs.analchem.9b02663] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Detailed studies of lipids in biological systems, including their role in cellular structure, metabolism, and disease development, comprise an increasingly prominent discipline called lipidomics. However, the conventional lipidomics tools, such as mass spectrometry, cannot investigate lipidomes until they are extracted, and thus they cannot be used for probing the lipid distribution nor for studying in live cells. Furthermore, conventional techniques rely on the lipid extraction from relatively large samples, which averages the data across the cellular populations and masks essential cell-to-cell variations. Further advancement of the discipline of lipidomics critically depends on the capability of high-resolution lipid profiling in live cells and, potentially, in single organelles. Here we report a micro-Raman assay designed for single-organelle lipidomics. We demonstrate how Raman microscopy can be used to measure the local intracellular biochemical composition and lipidome hallmarks-lipid concentration and unsaturation level, cis/trans isomer ratio, sphingolipids and cholesterol levels in live cells-with a sub-micrometer resolution, which is sufficient for profiling of subcellular structures. These lipidome data were generated by a newly developed biomolecular component analysis software, which provides a shared platform for data analysis among different research groups. We outline a robust, reliable, and user-friendly protocol for quantitative analysis of lipid profiles in subcellular structures. This method expands the capabilities of Raman-based lipidomics toward the analysis of single organelles within either live or fixed cells, thus allowing an unprecedented measure of organellar lipid heterogeneity and opening new quantitative ways to study the phenotypic variability in normal and diseased cells.
Collapse
Affiliation(s)
- Adrian Lita
- Neuro-Oncology Branch, Center for Cancer Research , National Cancer Institute, National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Andrey N Kuzmin
- Advanced Cytometry Instrumentation Systems, LLC , 19 Elm Street , Buffalo , New York 14203 , United States.,Institute for Lasers, Photonics and Biophotonics , University at Buffalo, State University of New York , Buffalo , New York 14260 , United States
| | - Artem Pliss
- Advanced Cytometry Instrumentation Systems, LLC , 19 Elm Street , Buffalo , New York 14203 , United States.,Institute for Lasers, Photonics and Biophotonics , University at Buffalo, State University of New York , Buffalo , New York 14260 , United States
| | - Alexander Baev
- Institute for Lasers, Photonics and Biophotonics , University at Buffalo, State University of New York , Buffalo , New York 14260 , United States
| | - Alexander Rzhevskii
- Thermo Fisher Scientific , 2 Radcliff Road, Tewksbury , Massachusetts 01876 , United States
| | - Mark R Gilbert
- Neuro-Oncology Branch, Center for Cancer Research , National Cancer Institute, National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Mioara Larion
- Neuro-Oncology Branch, Center for Cancer Research , National Cancer Institute, National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Paras N Prasad
- Institute for Lasers, Photonics and Biophotonics , University at Buffalo, State University of New York , Buffalo , New York 14260 , United States
| |
Collapse
|
22
|
Hashimoto T, Yokokawa T, Narusawa R, Okada Y, Kawaguchi R, Higashida K. A lactate-based compound containing caffeine in addition to voluntary running exercise decreases subcutaneous fat mass and improves glucose metabolism in obese rats. J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.03.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
|
23
|
Abstract
Lipid droplets are storage organelles at the centre of lipid and energy homeostasis. They have a unique architecture consisting of a hydrophobic core of neutral lipids, which is enclosed by a phospholipid monolayer that is decorated by a specific set of proteins. Originating from the endoplasmic reticulum, lipid droplets can associate with most other cellular organelles through membrane contact sites. It is becoming apparent that these contacts between lipid droplets and other organelles are highly dynamic and coupled to the cycles of lipid droplet expansion and shrinkage. Importantly, lipid droplet biogenesis and degradation, as well as their interactions with other organelles, are tightly coupled to cellular metabolism and are critical to buffer the levels of toxic lipid species. Thus, lipid droplets facilitate the coordination and communication between different organelles and act as vital hubs of cellular metabolism.
Collapse
Affiliation(s)
- James A Olzmann
- Department of Nutritional Sciences and Toxicology, University of California-Berkeley, Berkeley, CA, USA.
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
| |
Collapse
|
24
|
Morén B, Hansson B, Negoita F, Fryklund C, Lundmark R, Göransson O, Stenkula KG. EHD2 regulates adipocyte function and is enriched at cell surface-associated lipid droplets in primary human adipocytes. Mol Biol Cell 2019; 30:1147-1159. [PMID: 30811273 PMCID: PMC6724522 DOI: 10.1091/mbc.e18-10-0680] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Adipocytes play a central role in energy balance, and dysfunctional adipose tissue severely affects systemic energy homeostasis. The ATPase EH domain–containing 2 (EHD2) has previously been shown to regulate caveolae, plasma membrane-specific domains that are involved in lipid uptake and signal transduction. Here, we investigated the role of EHD2 in adipocyte function. We demonstrate that EHD2 protein expression is highly up-regulated at the onset of triglyceride accumulation during adipocyte differentiation. Small interfering RNA–mediated EHD2 silencing affected the differentiation process and impaired insulin sensitivity, lipid storage capacity, and lipolysis. Fluorescence imaging revealed localization of EHD2 to caveolae, close to cell surface–associated lipid droplets in primary human adipocytes. These lipid droplets stained positive for glycerol transporter aquaporin 7 and phosphorylated perilipin-1 following adrenergic stimulation. Further, EHD2 overexpression in human adipocytes increased the lipolytic signaling and suppressed the activity of transcription factor PPARγ. Overall, these data suggest that EHD2 plays a key role for adipocyte function.
Collapse
Affiliation(s)
- Björn Morén
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Björn Hansson
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Florentina Negoita
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Claes Fryklund
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Richard Lundmark
- Medical Biochemistry and Biophysics, Umeå University, 901 87 Umeå, Sweden
| | - Olga Göransson
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| | - Karin G Stenkula
- Department of Experimental Medical Science, Lund University, 223 84 Lund, Sweden
| |
Collapse
|
25
|
Fujisawa R, Iwamura T, Leproux P, Couderc V, Okada H, Kano H. Ultrabroadband Multiplex Coherent anti-Stokes Raman Scattering (CARS) Microspectroscopy Using a CCD Camera with an InGaAs Image Intensifier. CHEM LETT 2018. [DOI: 10.1246/cl.180017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Rie Fujisawa
- Konicaminolta Inc., No. 1 Sakura-machi, Hino, Tokyo 191-8511, Japan
| | - Takumi Iwamura
- Department of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
| | - Philippe Leproux
- Institut de Recherche XLIM, UMR CNRS No. 7252, 123 Avenue Albert Thomas, 87060 Limoges CEDEX, France
| | - Vincent Couderc
- Institut de Recherche XLIM, UMR CNRS No. 7252, 123 Avenue Albert Thomas, 87060 Limoges CEDEX, France
| | - Hisatake Okada
- Konicaminolta Inc., No. 1 Sakura-machi, Hino, Tokyo 191-8511, Japan
| | - Hideaki Kano
- Department of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
- Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573, Japan
- Tsukuba Research Center for Energy Materials Science (TREMS), University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan
| |
Collapse
|
26
|
Abstract
Long considered inert fat storage depots, it has become clear that lipid droplets (LDs) are bona fide organelles. Like other organelles, they have a characteristic complement of proteins and lipids, and undergo a life cycle that includes biogenesis, maturation, interactions with other organelles, and turnover. I will discuss recent insights into mechanisms governing the life cycle of LDs, and compare and contrast the LD life cycle with that of other metabolic organelles such as mitochondria, peroxisomes, and autophagosomes, highlighting open questions in the field.
Collapse
Affiliation(s)
- Sarah Cohen
- University of North Carolina, Chapel Hill, NC, United States.
| |
Collapse
|
27
|
Raman Microscopy: A Noninvasive Method to Visualize the Localizations of Biomolecules in the Cornea. Cornea 2018; 36 Suppl 1:S67-S71. [PMID: 28902016 DOI: 10.1097/ico.0000000000001369] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE In vivo and in situ visualization of biomolecules without pretreatment will be important for diagnosis and treatment of ocular disorders in the future. Recently, multiphoton microscopy, based on the nonlinear interactions between molecules and photons, has been applied to reveal the localizations of various molecules in tissues. We aimed to use multimodal multiphoton microscopy to visualize the localizations of specific biomolecules in rat corneas. METHODS Multiphoton images of the corneas were obtained from nonlinear signals of coherent anti-Stokes Raman scattering, third-order sum frequency generation, and second-harmonic generation. RESULTS The localizations of the adhesion complex-containing basement membrane and Bowman layer were clearly visible in the third-order sum frequency generation images. The fine structure of type I collagen was observed in the corneal stroma in the second-harmonic generation images. The localizations of lipids, proteins, and nucleic acids (DNA/RNA) was obtained in the coherent anti-Stokes Raman scattering images. CONCLUSIONS Imaging technologies have progressed significantly and been applied in medical fields. Optical coherence tomography and confocal microscopy are widely used but do not provide information on the molecular structure of the cornea. By contrast, multiphoton microscopy provides information on the molecular structure of living tissues. Using this technique, we successfully visualized the localizations of various biomolecules including lipids, proteins, and nucleic acids in the cornea. We speculate that multiphoton microscopy will provide essential information on the physiological and pathological conditions of the cornea, as well as molecular localizations in tissues without pretreatment.
Collapse
|
28
|
Melatonin promotes triacylglycerol accumulation via MT2 receptor during differentiation in bovine intramuscular preadipocytes. Sci Rep 2017; 7:15080. [PMID: 29118419 PMCID: PMC5678110 DOI: 10.1038/s41598-017-12780-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 09/14/2017] [Indexed: 12/22/2022] Open
Abstract
Melatonin (N-acetyl-5-methoxytryptamine) is a derivative of tryptophan which is produced and secreted mainly by the pineal gland and regulates a variety of important central and peripheral actions. To examine the potential effects of melatonin on the proliferation and differentiation of bovine intramuscular preadipocytes (BIPs), BIPs were incubated with different concentrations of melatonin. Melatonin supplementation at 1 mM significantly increased peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein (C/EBP) β, and C/EBPα expression and promoted the differentiation of BIPs into adipocytes with large lipid droplets and high cellular triacylglycerol (TAG) levels. Melatonin also significantly enhanced lipolysis and up-regulated the expression of lipolytic genes and proteins, including hormone sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), and perilipin 1 (PLIN1). Moreover, melatonin reduced intracellular reactive oxygen species (ROS) levels by increasing the expression levels and activities of superoxide dismutase 1 (SOD1) and glutathione peroxidase 4 (GPX4). Finally, the positive effects of melatonin on adipogenesis, lipolysis, and redox status were reversed by treatment with luzindole, anantagonist of nonspecific melatonin receptors 1 (MT1) and 2 (MT2), and 4-phenyl-2-propionamidotetraline (4P-PDOT), a selective MT2 antagonist. These results reveal that melatonin promotes TAG accumulation via MT2 receptor during differentiation in BIPs.
Collapse
|
29
|
Marinozzi MR, Pandolfi L, Malatesta M, Colombo M, Collico V, Lievens PMJ, Tambalo S, Lasconi C, Vurro F, Boschi F, Mannucci S, Sbarbati A, Prosperi D, Calderan L. Innovative approach to safely induce controlled lipolysis by superparamagnetic iron oxide nanoparticles-mediated hyperthermic treatment. Int J Biochem Cell Biol 2017; 93:62-73. [PMID: 29111382 DOI: 10.1016/j.biocel.2017.10.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 10/19/2017] [Accepted: 10/23/2017] [Indexed: 02/06/2023]
Abstract
During last years, evidence has been provided on the involvement of overweight and obesity in the pathogenesis and aggravation of several life-threatening diseases. Here, we demonstrate that, under appropriate administration conditions, polyhedral iron oxide nanoparticles are efficiently and safely taken up by 3T3 cell line-derived adipocytes (3T3 adipocytes) in vitro. Since these nanoparticles proved to effectively produce heat when subjected to alternating magnetic field, 3T3 adipocytes were submitted to superparamagnetic iron oxide nanoparticles-mediated hyperthermia treatment (SMHT), with the aim of modulating their lipid content. Notably, the treatment resulted in a significant delipidation persisting for at least 24h, and in the absence of cell death, damage or dedifferentiation. Interestingly, transcript expression of adipose triglyceride lipase (ATGL), a key gene involved in canonical lipolysis, was not modulated upon SMHT, suggesting the involvement of a novel/alternative mechanism in the effective lipolysis observed. By applying the same experimental conditions successfully used for 3T3 adipocytes, SMHT was able to induce delipidation also in primary cultures of human adipose-derived adult stem cells. The success of this pioneering approach in vitro opens promising perspectives for the application of SMHT in vivo as an innovative safe and physiologically mild strategy against obesity, potentially useful in association with balanced diet and healthy lifestyle.
Collapse
Affiliation(s)
- Maria Rosaria Marinozzi
- Dipartimento di Neuroscienze, Biomedicina e Movimento, Università di Verona, 37134 Verona, Italy
| | - Laura Pandolfi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
| | - Manuela Malatesta
- Dipartimento di Neuroscienze, Biomedicina e Movimento, Università di Verona, 37134 Verona, Italy
| | - Miriam Colombo
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
| | - Veronica Collico
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy
| | | | - Stefano Tambalo
- Dipartimento di Neuroscienze, Biomedicina e Movimento, Università di Verona, 37134 Verona, Italy; Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, 38068 Rovereto, Italy
| | - Chiara Lasconi
- Dipartimento di Neuroscienze, Biomedicina e Movimento, Università di Verona, 37134 Verona, Italy
| | - Federica Vurro
- Dipartimento di Neuroscienze, Biomedicina e Movimento, Università di Verona, 37134 Verona, Italy
| | - Federico Boschi
- Dipartimento di Informatica, Università di Verona, 37134 Verona, Italy
| | - Silvia Mannucci
- Dipartimento di Neuroscienze, Biomedicina e Movimento, Università di Verona, 37134 Verona, Italy
| | - Andrea Sbarbati
- Dipartimento di Neuroscienze, Biomedicina e Movimento, Università di Verona, 37134 Verona, Italy
| | - Davide Prosperi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy.
| | - Laura Calderan
- Dipartimento di Neuroscienze, Biomedicina e Movimento, Università di Verona, 37134 Verona, Italy.
| |
Collapse
|
30
|
Engin A. Fat Cell and Fatty Acid Turnover in Obesity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 960:135-160. [PMID: 28585198 DOI: 10.1007/978-3-319-48382-5_6] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. Inhibition of adipose triglyceride lipase leads to an accumulation of triglyceride, whereas inhibition of hormone-sensitive lipase leads to the accumulation of diacylglycerol. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride turnover. Excess triacylglycerols (TAGs), sterols and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets. Following the release of lipid droplets from endoplasmic reticulum, cytoplasmic lipid droplets increase their volume either by local TAG synthesis or by homotypic fusion. The number and the size of lipid droplet distribution is correlated with obesity. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. NOD-like receptors family pyrin domain containing 3 (NLRP3) inflammasome-dependent caspase-1 activation in hypertrophic adipocytes induces obese adipocyte death by pyroptosis. Actually adipocyte death may be a prerequisite for the transition from hypertrophic to hyperplastic obesity. Major transcriptional factors, CCAAT/enhancer-binding proteins beta and delta, play a central role in the subsequent induction of critical regulators, peroxisome-proliferator-activated receptor gamma, CCAAT/enhancer-binding protein alpha and sterol regulatory element-binding protein 1, in the transcriptional control of adipogenesis in obesity.Collectively, in this chapter the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of lipid droplet interactions with the other cellular organelles are reviewed. Furthermore, in addition to lipid droplet growth, the functional link between the adipocyte-specific lipid droplet-associated protein and fatty acid turn-over is also debated.
Collapse
Affiliation(s)
- Atilla Engin
- Faculty of Medicine, Department of General Surgery, Gazi University, Besevler, Ankara, Turkey. .,, Mustafa Kemal Mah. 2137. Sok. 8/14, 06520, Cankaya, Ankara, Turkey.
| |
Collapse
|
31
|
Chitraju C, Mejhert N, Haas JT, Diaz-Ramirez LG, Grueter CA, Imbriglio JE, Pinto S, Koliwad SK, Walther TC, Farese RV. Triglyceride Synthesis by DGAT1 Protects Adipocytes from Lipid-Induced ER Stress during Lipolysis. Cell Metab 2017; 26:407-418.e3. [PMID: 28768178 PMCID: PMC6195226 DOI: 10.1016/j.cmet.2017.07.012] [Citation(s) in RCA: 211] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 04/10/2017] [Accepted: 07/17/2017] [Indexed: 12/29/2022]
Abstract
Triglyceride (TG) storage in adipose tissue provides the major reservoir for metabolic energy in mammals. During lipolysis, fatty acids (FAs) are hydrolyzed from adipocyte TG stores and transported to other tissues for fuel. For unclear reasons, a large portion of hydrolyzed FAs in adipocytes is re-esterified to TGs in a "futile," ATP-consuming, energy dissipating cycle. Here we show that FA re-esterification during adipocyte lipolysis is mediated by DGAT1, an ER-localized DGAT enzyme. Surprisingly, this re-esterification cycle does not preserve TG mass but instead functions to protect the ER from lipotoxic stress and related consequences, such as adipose tissue inflammation. Our data reveal an important role for DGAT activity and TG synthesis generally in averting ER stress and lipotoxicity, with specifically DGAT1 performing this function during stimulated lipolysis in adipocytes.
Collapse
Affiliation(s)
- Chandramohan Chitraju
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Niklas Mejhert
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Joel T Haas
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA
| | | | - Carrie A Grueter
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA
| | | | | | - Suneil K Koliwad
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, USA; Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
| |
Collapse
|
32
|
Chen X, Firdaus SJ, Howard AD, Soulages JL, Arrese EL. Clues on the function of Manduca sexta perilipin 2 inferred from developmental and nutrition-dependent changes in its expression. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 81:19-31. [PMID: 27939924 PMCID: PMC5292285 DOI: 10.1016/j.ibmb.2016.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 11/17/2016] [Accepted: 12/02/2016] [Indexed: 06/06/2023]
Abstract
Cellular triglycerides (TG) are stored in cytosolic lipid droplets (LDs). Perilipins (PLIN) are a group of LD-proteins that play important roles in the assembly and transport of LDs and in TG metabolism. Two members of the PLIN family are found in insects (PLIN1 & 2 or Lsd1 & 2). We have cloned and expressed Manduca sexta PLIN2 (MsPLIN2), and studied developmental and nutritional changes in the expression of PLIN2. Nutritional changes induced fast alterations in PLIN2 mRNA and protein levels in fat body and midgut of the feeding larvae. The relationship observed between PLIN2 expression and TG synthesis in both larval fat body and midgut suggests that PLIN2 is needed when tissues are accumulating TG. However, when the fat body was storing TG at maximal capacity, MsPLIN2 levels declined. This unexpected finding suggests the occurrence of alternative mechanism/s to shield TG from the action of lipases in M. sexta LDs. In addition, it implies that the cellular level of lipid storage could be modulating MsPLIN2 expression and/or degradation. The study also confirmed that MsPLIN2 was most abundant in the adult fat body, which is characterized by a high rate of TG hydrolysis and lipid mobilization. Whether MsPLIN2 is directly involved in lipolysis and/or the secretion of lipids in the fat body of adult of M. sexta is unknown at this time. Nonetheless, the coexistence of high PLIN2 and lipolysis levels suggests a complex role for MsPLIN2. Altogether, we found that MsPLIN2 is needed when the synthesis of glycerides, DG and TG, is active even if the insect is accumulating or consuming TG.
Collapse
Affiliation(s)
- Xiao Chen
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Sarah J Firdaus
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Alisha D Howard
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Jose L Soulages
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA
| | - Estela L Arrese
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK 74078, USA.
| |
Collapse
|
33
|
Abstract
Lipid droplets are the universal cellular organelles for the transient or long-term storage of lipids. The number, size and composition of lipid droplets vary greatly within cells in a homogenous population as well as in different cell types. The variability of intracellular lipid-storage organelles reflects the diversification of lipid droplet composition and function. Lipid droplet diversification results, for example, in two cellular lipid droplet populations that are prone to diminish and grow, respectively. The aberrant accumulation or depletion of lipids are hallmarks or causes of various human pathologies. Thus, a better understanding of the origins of lipid droplet diversification is not only a fascinating cell biology question but also potentially serves to improve comprehension of pathologies that entail the accumulation of lipids. This Commentary covers the lipid droplet life cycle and highlights the early steps during lipid droplet biogenesis, which we propose to be the potential driving forces of lipid droplet diversification.
Collapse
Affiliation(s)
- Abdou Rachid Thiam
- Laboratoire de Physique Statistique, École Normale Supérieure, PSL Research University; Université Paris Diderot Sorbonne Paris-Cité; Sorbonne Universités UPMC Univ Paris 06; CNRS; 24 rue Lhomond, Paris 75005, France
| | - Mathias Beller
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University, Universitätsstr. 1, Düsseldorf 40225, Germany .,Systems Biology of Lipid Metabolism, Heinrich Heine University, Universitätsstr. 1, Düsseldorf 40225, Germany
| |
Collapse
|
34
|
Flachs P, Adamcova K, Zouhar P, Marques C, Janovska P, Viegas I, Jones JG, Bardova K, Svobodova M, Hansikova J, Kuda O, Rossmeisl M, Liisberg U, Borkowska AG, Kristiansen K, Madsen L, Kopecky J. Induction of lipogenesis in white fat during cold exposure in mice: link to lean phenotype. Int J Obes (Lond) 2016; 41:372-380. [PMID: 28008171 DOI: 10.1038/ijo.2016.228] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 11/10/2016] [Accepted: 11/24/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND/OBJECTIVE Futile substrate cycling based on lipolytic release of fatty acids (FA) from intracellular triacylglycerols (TAG) and their re-esterification (TAG/FA cycling), as well as de novo FA synthesis (de novo lipogenesis (DNL)), represent the core energy-consuming biochemical activities of white adipose tissue (WAT). We aimed to characterize their roles in cold-induced thermogenesis and energy homeostasis. METHODS Male obesity-resistant A/J and obesity-prone C57BL/6J mice maintained at 30 °C were exposed to 6 °C for 2 or 7 days. In epididymal WAT (eWAT), TAG synthesis and DNL were determined using in vivo 2H incorporation from 2H2O into tissue TAG and nuclear magnetic resonance spectroscopy. Quantitative real-time-PCR and/or immunohistochemistry and western blotting were used to determine the expression of selected genes and proteins in WAT and liver. RESULTS The mass of WAT depots declined during cold exposure (CE). Plasma levels of TAG and non-esterified FA were decreased by day 2 but tended to normalize by day 7 of CE. TAG synthesis (reflecting TAG/FA cycle activity) gradually increased during CE. DNL decreased by day 2 of CE but increased several fold over the control values by day 7. Expression of genes involved in lipolysis, glyceroneogenesis, FA re-esterification, FA oxidation and mitochondrial biogenesis in eWAT was induced during CE. All these changes were more pronounced in obesity-resistant A/J than in B6 mice and occurred in the absence of uncoupling protein 1 in eWAT. Expression of markers of glyceroneogenesis in eWAT correlated negatively with hepatic FA synthesis by day 7 in both strains. Leptin and fibroblast growth factor 21 plasma levels were differentially affected by CE in the two mouse strains. CONCLUSIONS Our results indicate integrated involvement of (i) TAG/FA cycling and DNL in WAT, and (ii) hepatic very-low-density lipoprotein-TAG synthesis in the control of blood lipid levels and provision of FA fuels for thermogenesis in cold. They suggest that lipogenesis in WAT contributes to a lean phenotype.
Collapse
Affiliation(s)
- P Flachs
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - K Adamcova
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - P Zouhar
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - C Marques
- Centre for Neuroscience and Cell Biology, University of Coimbra, Cantanhede, Portugal
| | - P Janovska
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - I Viegas
- Centre for Neuroscience and Cell Biology, University of Coimbra, Cantanhede, Portugal
| | - J G Jones
- Centre for Neuroscience and Cell Biology, University of Coimbra, Cantanhede, Portugal
| | - K Bardova
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - M Svobodova
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - J Hansikova
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - O Kuda
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - M Rossmeisl
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - U Liisberg
- Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,National Institute of Nutrition and Seafood Research, Bergen, Norway
| | - A G Borkowska
- Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - K Kristiansen
- Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,BGI-Shenzhen, Shenzhen, China
| | - L Madsen
- Laboratory of Genomics and Molecular Biomedicine, Department of Biology, University of Copenhagen, Copenhagen, Denmark.,National Institute of Nutrition and Seafood Research, Bergen, Norway
| | - J Kopecky
- Department of Adipose Tissue Biology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| |
Collapse
|
35
|
Moriuchi T, Kuroda M, Kusumoto F, Osumi T, Hirose F. Lamin A reassembly at the end of mitosis is regulated by its SUMO-interacting motif. Exp Cell Res 2016; 342:83-94. [DOI: 10.1016/j.yexcr.2016.02.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2015] [Revised: 02/22/2016] [Accepted: 02/23/2016] [Indexed: 02/01/2023]
|
36
|
Takanezawa S, Morita SI, Ozaki Y, Sako Y. Raman spectral dynamics of single cells in the early stages of growth factor stimulation. Biophys J 2016; 108:2148-57. [PMID: 25954873 DOI: 10.1016/j.bpj.2015.03.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 03/18/2015] [Accepted: 03/23/2015] [Indexed: 11/18/2022] Open
Abstract
Cell fates change dynamically in response to various extracellular signals, including growth factors that stimulate differentiation and proliferation. The processes underlying cell-fate decisions are complex and often include large cell-to-cell variations, even within a clonal population in the same environment. To understand the origins of these cell-to-cell variations, we must detect the internal dynamics of single cells that reflect their changing chemical milieu. In this study, we used the Raman spectra of single cells to trace their internal dynamics during the early stages of growth factor stimulation. This method allows nondestructive and inclusive time-series analyses of chemical compositions of the same single cells. Applying a Gaussian mixture model to the major principal components of the single-cell Raman spectra, we detected the dynamics of the chemical states in MCF-7 cancer-derived cells in the absence and presence of differentiation and proliferation factors. The dynamics displayed characteristic variations according to the functions of the growth factors. In the differentiation pathway, the chemical composition changed directionally between multiple states, including both reversible and irreversible state transitions. In contrast, in the proliferation pathway, the chemical composition was homogenized into a single state. The differentiation factor also stimulated fluctuations in the chemical composition, whereas the proliferation factor did not.
Collapse
Affiliation(s)
- Sota Takanezawa
- Cellular Informatics Laboratory, RIKEN, Wako, Japan; Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Japan
| | | | - Yukihiro Ozaki
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Japan
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN, Wako, Japan.
| |
Collapse
|
37
|
Segawa H, Okuno M, Leproux P, Couderc V, Ozawa T, Kano H. Multimodal imaging of living cells with multiplex coherent anti-stokes raman scattering (CARS), third-order sum frequency generation (TSFG) and two-photon excitation fluorescence (TPEF) using a nanosecond white-light laser source. ANAL SCI 2016; 31:299-305. [PMID: 25864673 DOI: 10.2116/analsci.31.299] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The subnanosecond "white-light laser" source has been applied to multimodal, multiphoton, and multiplex spectroscopic imaging (M(3) spectroscopic imaging) with coherent anti-Stokes Raman scattering (CARS), third-order sum frequency generation (TSFG), and two-photon excitation fluorescence (TPEF). As the proof-of-principle experiment, we performed simultaneous imaging of polystyrene beads with TSFG and TPEF. This technique is then applied to live cell imaging. Mouse L929 fibroblastic cells are clearly visualized by CARS, TSFG, and TPEF processes. M(3) spectroscopic imaging provides various and unique cellular information with different image contrast based on each multiphoton process.
Collapse
Affiliation(s)
- Hiroki Segawa
- Department of Chemistry, School of Science, The University of Tokyo
| | | | | | | | | | | |
Collapse
|
38
|
Daemen S, van Zandvoort MAMJ, Parekh SH, Hesselink MKC. Microscopy tools for the investigation of intracellular lipid storage and dynamics. Mol Metab 2015; 5:153-163. [PMID: 26977387 PMCID: PMC4770264 DOI: 10.1016/j.molmet.2015.12.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 12/19/2015] [Accepted: 12/27/2015] [Indexed: 12/01/2022] Open
Abstract
Background Excess storage of lipids in ectopic tissues, such as skeletal muscle, liver, and heart, seems to associate closely with metabolic abnormalities and cardiac disease. Intracellular lipid storage occurs in lipid droplets, which have gained attention as active organelles in cellular metabolism. Recent developments in high-resolution microscopy and microscopic spectroscopy have opened up new avenues to examine the physiology and biochemistry of intracellular lipids. Scope of review The aim of this review is to give an overview of recent technical advances in microscopy, and its application for the visualization, identification, and quantification of intracellular lipids, with special focus to lipid droplets. In addition, we attempt to summarize the probes currently available for the visualization of lipids. Major conclusions The continuous development of lipid probes in combination with the rapid development of microscopic techniques can provide new insights in the role and dynamics of intracellular lipids. Moreover, in situ identification of intracellular lipids is now possible and promises to add a new dimensionality to analysis of lipid biochemistry, and its relation to (patho)physiology.
Collapse
Key Words
- BODIPY, Boron-dipyrromethene
- CARS, coherent anti-stokes Raman scattering
- CLEM, correlative light electron microscopy
- CLSM, confocal laser scanning microscopy
- DIC, differential interference microscopy
- FA, fatty acid
- FIB-SEM, focused ion beam scanning electron microscopy
- FLIP, fluorescence loss in photobleaching
- FRAP, fluorescent recovery after photobleaching
- FRET, fluorescence resonance energy transfer
- Fluorescent lipid probes
- GFP, green fluorescent protein
- HCV, hepatitis C virus
- LD, lipid droplet
- Lipid droplets
- Live-cell imaging
- Metabolic disease
- NBD, nitro-benzoxadiazolyl
- PALM, photoactivation localization microscopy
- SBEM, serial block face scanning electron microscopy
- SIMS, Secondary Ion Mass Spectrometry
- SRS, Stimulated Raman Scattering
- STED, stimulated emission depletion
- STORM, stochastic optical reconstruction microscopy
- Super-resolution
- TAG, triacylglycerol
- TEM, transmission electron microscopy
- TOF-SIMS, time-of-flight SIMS
- TPLSM, two-photon laser scanning microscopy
- Vibrational microscopy
Collapse
Affiliation(s)
- Sabine Daemen
- Department of Human Movement Sciences and Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands.
| | - Marc A M J van Zandvoort
- Department of Genetics and Molecular Cell Biology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands; Institute for Molecular Cardiovascular Research (IMCAR), RWTH Aachen University, Aachen, Germany.
| | - Sapun H Parekh
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz, Germany.
| | - Matthijs K C Hesselink
- Department of Human Movement Sciences and Human Biology, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands.
| |
Collapse
|
39
|
Billecke N, Bosma M, Rock W, Fleissner F, Best G, Schrauwen P, Kersten S, Bonn M, Hesselink MKC, Parekh SH. Perilipin 5 mediated lipid droplet remodelling revealed by coherent Raman imaging. Integr Biol (Camb) 2015; 7:467-76. [PMID: 25804837 DOI: 10.1039/c4ib00271g] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Accumulation of fat in muscle tissue as intramyocellular lipids (IMCLs) is closely related to the development of insulin resistance and subsequent type 2 diabetes. Most IMCLs organize into lipid droplets (LDs), the fates of which are regulated by lipid droplet coat proteins. Perilipin 5 (PLIN5) is an LD coating protein, which is strongly linked to lipid storage in muscle tissue. Here we employ a tandem in vitro/ex vivo approach and use chemical imaging by label-free, hyperspectral coherent Raman microscopy to quantify compositional changes in individual LDs upon PLIN5 overexpression. Our results directly show that PLIN5 overexpression in muscle alters individual LD composition and physiology, resulting in larger LDs with higher esterified acyl chain concentration, increased methylene content, and more saturated lipid species. These results suggest that lipotoxic protection afforded by natural PLIN5 upregulation in muscle involves molecular changes in lipid composition within LDs.
Collapse
Affiliation(s)
- Nils Billecke
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Kato H, Tanaka G, Masuda S, Ogasawara J, Sakurai T, Kizaki T, Ohno H, Izawa T. Melatonin promotes adipogenesis and mitochondrial biogenesis in 3T3-L1 preadipocytes. J Pineal Res 2015; 59:267-75. [PMID: 26123001 DOI: 10.1111/jpi.12259] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/26/2015] [Indexed: 01/16/2023]
Abstract
Melatonin is synthesized in the pineal gland, but elicits a wide range of physiological responses in peripheral target tissues. Recent advances suggest that melatonin controls adiposity, resulting in changes in body weight. The aim of this study was to investigate the effect of melatonin on adipogenesis and mitochondrial biogenesis in 3T3-L1 mouse embryo fibroblasts. Melatonin significantly increased the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), a master regulator of adipogenesis, and promoted differentiation into adipocytes. Melatonin-treated cells also formed smaller lipid droplets and abundantly expressed several molecules associated with lipolysis, including adipose triglyceride lipase, perilipin, and comparative gene identification-58. Moreover, the hormone promoted biogenesis of mitochondria, as indicated by fluorescent staining, elevated the citrate synthase activity, and upregulated the expression of PPAR-γ coactivator 1 α, nuclear respiratory factor-1, and transcription factor A. The expression of uncoupling protein 1 was also observable both at mRNA and at protein level in melatonin-treated cells. Finally, adiponectin secretion and the expression of adiponectin receptors were enhanced. These results suggest that melatonin promotes adipogenesis, lipolysis, mitochondrial biogenesis, and adiponectin secretion. Thus, melatonin has potential as an anti-obesity agent that may reverse obesity-related disorders.
Collapse
Affiliation(s)
- Hisashi Kato
- Graduate School of Health and Sports Science, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Goki Tanaka
- Graduate School of Health and Sports Science, Doshisha University, Kyotanabe, Kyoto, Japan
| | - Shinya Masuda
- Division of Diabetic Research, Clinical Research Institute, National Hospital Organization, Kyoto Medical Center, Fushimi, Kyoto, Japan
| | - Junetsu Ogasawara
- Department of Molecular Predictive Medicine and Sports Science, Kyorin University, Mitaka, Tokyo, Japan
| | - Takuya Sakurai
- Department of Molecular Predictive Medicine and Sports Science, Kyorin University, Mitaka, Tokyo, Japan
| | - Takako Kizaki
- Department of Molecular Predictive Medicine and Sports Science, Kyorin University, Mitaka, Tokyo, Japan
| | - Hideki Ohno
- Department of Molecular Predictive Medicine and Sports Science, Kyorin University, Mitaka, Tokyo, Japan
| | - Tetsuya Izawa
- Graduate School of Health and Sports Science, Doshisha University, Kyotanabe, Kyoto, Japan
- Faculty of Health and Sports Science, Doshisha University, Kyotanabe, Kyoto, Japan
| |
Collapse
|
41
|
Eichmann TO, Grumet L, Taschler U, Hartler J, Heier C, Woblistin A, Pajed L, Kollroser M, Rechberger G, Thallinger GG, Zechner R, Haemmerle G, Zimmermann R, Lass A. ATGL and CGI-58 are lipid droplet proteins of the hepatic stellate cell line HSC-T6. J Lipid Res 2015; 56:1972-84. [PMID: 26330055 PMCID: PMC4583087 DOI: 10.1194/jlr.m062372] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Indexed: 12/31/2022] Open
Abstract
Lipid droplets (LDs) of hepatic stellate cells (HSCs) contain large amounts of vitamin A [in the form of retinyl esters (REs)] as well as other neutral lipids such as TGs. During times of insufficient vitamin A availability, RE stores are mobilized to ensure a constant supply to the body. To date, little is known about the enzymes responsible for the hydrolysis of neutral lipid esters, in particular of REs, in HSCs. In this study, we aimed to identify LD-associated neutral lipid hydrolases by a proteomic approach using the rat stellate cell line HSC-T6. First, we loaded cells with retinol and FAs to promote lipid synthesis and deposition within LDs. Then, LDs were isolated and lipid composition and the LD proteome were analyzed. Among other proteins, we found perilipin 2, adipose TG lipase (ATGL), and comparative gene identification-58 (CGI-58), known and established LD proteins. Bioinformatic search of the LD proteome for α/β-hydrolase fold-containing proteins revealed no yet uncharacterized neutral lipid hydrolases. In in vitro activity assays, we show that rat (r)ATGL, coactivated by rat (r)CGI-58, efficiently hydrolyzes TGs and REs. These findings suggest that rATGL and rCGI-58 are LD-resident proteins in HSCs and participate in the mobilization of both REs and TGs.
Collapse
Affiliation(s)
- Thomas O Eichmann
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Lukas Grumet
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Ulrike Taschler
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Jürgen Hartler
- Bioinformatics, Institute for Knowledge Discovery, Graz University of Technology, Graz, Austria
| | - Christoph Heier
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Aaron Woblistin
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Laura Pajed
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Manfred Kollroser
- Institute of Forensic Medicine, Medical University of Graz, Graz, Austria
| | - Gerald Rechberger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria BioTechMed-Graz, Graz, Austria OMICS Center, Graz, Austria
| | - Gerhard G Thallinger
- Bioinformatics, Institute for Knowledge Discovery, Graz University of Technology, Graz, Austria BioTechMed-Graz, Graz, Austria OMICS Center, Graz, Austria
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Günter Haemmerle
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Robert Zimmermann
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Achim Lass
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| |
Collapse
|
42
|
Asymmetrical diacylglycerol dynamics on the cytosolic and lumenal sides of a single endomembrane in living cells. Sci Rep 2015; 5:12960. [PMID: 26264517 PMCID: PMC4533005 DOI: 10.1038/srep12960] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 07/09/2015] [Indexed: 01/04/2023] Open
Abstract
The elucidation of lipid dynamics on the cytosolic and lumenal sides of a single endomembrane has been challenging in living cells because of the lack of appropriate methods. Diacylglycerol (DAG) is a lipid second messenger that is produced by enzymes that reside on both the cytosolic and lumenal sides of the endomembrane. In the present study, we attempted to observe both the cytosolic and lumenal DAG dynamics at endomembranes including the Golgi apparatus and the endoplasmic reticulum in Madin-Darby canine kidney (MDCK) cells. We developed a Förster resonance energy transfer (FRET)–based probe to detect DAG at the luminal side (lumenal DAG) of endomembranes. In combination with the FRET-based cytosolic DAG probe that has already been established, it was found that lumenal DAG is generated in a calcium-dependent manner by thapsigargin, which increases cytosolic calcium concentrations. In contrast, DAG production at the cytosolic side of endomembranes did not occur under the same experimental conditions. The thapsigargin-induced DAG generation was abolished by treatment with an inhibitor of sphingomyelin synthase (SMS) and phosphatidylcholine-specific phospholipase C (PC-PLC), which produce lumenal DAG. Thus, we have established a successful method for monitoring both cytosolic and lumenal DAG dynamics at the endomembrane in living cells.
Collapse
|
43
|
Yamaguchi T, Fujikawa N, Nimura S, Tokuoka Y, Tsuda S, Aiuchi T, Kato R, Obama T, Itabe H. Characterization of lipid droplets in steroidogenic MLTC-1 Leydig cells: Protein profiles and the morphological change induced by hormone stimulation. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1285-95. [PMID: 26143378 DOI: 10.1016/j.bbalip.2015.06.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 06/22/2015] [Accepted: 06/30/2015] [Indexed: 12/11/2022]
Abstract
Lipid droplets (LDs) are functional subcellular organelles involved in multiple intracellular processes. LDs are found in nearly all types of eukaryotic cells, but their properties are highly variable in different types of tissues. Steroidogenic cells synthesize steroid hormones de novo from the cholesterol deposited in cytosolic LDs. However, the roles of LD proteins in steroidogenesis under pituitary hormone stimulation have not been well elucidated. The protein profile of isolated LDs from the mouse Leydig tumor cell line MLTC-1 was distinct from that of hepatic cells or macrophages. By proteomic analysis of the components using mass spectrometry, two enzymes for steroidogenesis, 3β-hydroxysteroid dehydrogenase type 1 (3βHSD1) and 17 β-hydroxysteroid dehydrogenase type 11 (17βHSD11), were identified in two strong bands in the LD fractions. The LD fraction of MLTC-1 cells also included CYP11A1 and CYP17, suggesting that the LDs contain all the enzymes needed for testosterone synthesis. The steroidogenesis in Leydig cells is activated by luteinizing hormone through a PKA-dependent pathway. Stimulation of MLTC-1 cells with luteinizing hormone or 8-bromo-cAMP caused drastic changes in the morphology of the LDs in the MLTC-1 cells. Upon stimulation, large perinuclear LDs are turned into much smaller LDs and dispersed throughout the cytosol. These results raise the possibility that LDs are involved in a regulatory pathway of steroidogenesis, not just by serving as a storage depot for cholesterol esters, but also by providing enzymes and generating sites for enzymatic activity.
Collapse
Affiliation(s)
- Tomohiro Yamaguchi
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan.
| | - Noriyuki Fujikawa
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan
| | - Satomi Nimura
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan
| | - Yutaro Tokuoka
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan
| | - Sonoka Tsuda
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan
| | - Toshihiro Aiuchi
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan
| | - Rina Kato
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan
| | - Takashi Obama
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan
| | - Hiroyuki Itabe
- Division of Biological Chemistry, Department of Molecular Biology, Showa University School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan.
| |
Collapse
|
44
|
Rhinovirus uses a phosphatidylinositol 4-phosphate/cholesterol counter-current for the formation of replication compartments at the ER-Golgi interface. Cell Host Microbe 2014; 16:677-90. [PMID: 25525797 DOI: 10.1016/j.chom.2014.10.003] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 08/19/2014] [Accepted: 09/23/2014] [Indexed: 12/19/2022]
Abstract
Similar to other positive-strand RNA viruses, rhinovirus, the causative agent of the common cold, replicates on a web of cytoplasmic membranes, orchestrated by host proteins and lipids. The host pathways that facilitate the formation and function of the replication membranes and complexes are poorly understood. We show that rhinovirus replication depends on host factors driving phosphatidylinositol 4-phosphate (PI4P)-cholesterol counter-currents at viral replication membranes. Depending on the virus type, replication required phosphatidylinositol 4-kinase class 3beta (PI4K3b), cholesteryl-esterase hormone-sensitive lipase (HSL) or oxysterol-binding protein (OSBP)-like 1, 2, 5, 9, or 11 associated with lipid droplets, endosomes, or Golgi. Replication invariably required OSBP1, which shuttles cholesterol and PI4P between ER and Golgi at membrane contact sites. Infection also required ER-associated PI4P phosphatase Sac1 and phosphatidylinositol (PI) transfer protein beta (PITPb) shunting PI between ER-Golgi. These data support a PI4P-cholesterol counter-flux model for rhinovirus replication.
Collapse
|
45
|
Dugan CE, Cawthorn WP, MacDougald OA, Kennedy RT. Multiplexed microfluidic enzyme assays for simultaneous detection of lipolysis products from adipocytes. Anal Bioanal Chem 2014; 406:4851-9. [PMID: 24880873 PMCID: PMC4103022 DOI: 10.1007/s00216-014-7894-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 05/07/2014] [Accepted: 05/13/2014] [Indexed: 01/09/2023]
Abstract
Microfluidics has enabled new cell biology experiments. Incorporating chemical monitoring of cellular secretion into chips offers the potential to increase information content and utility of such systems. In this work, an integrated, multilayer polydimethylsiloxane microfluidic chip was developed to simultaneously measure fatty acids and glycerol secreted from cultured adipocytes on chip in near real time. Approximately 48,000 adipocytes were loaded into a cell chamber in a reversibly sealed chip. Cells were perfused at 0.75 μL/min. Cell perfusate was split and directed to separate, continuously operating fluorescent enzyme assay channel networks. The fluorescent assay products were detected simultaneously near the outlet of the chip. The fatty acid and glycerol assays had linear dynamic ranges of 150 and 110 μM and limit of detection (LOD) of 6 and 5 μM, respectively. Surface modifications including pretreatment with sodium dodecyl sulfate were utilized to prevent adsorption of fatty acids to the chip surface. Using the chip, basal fatty acid and glycerol concentrations ranged from 0.18 to 0.7 nmol × 10(6) cell(-1) min(-1) and from 0.23 to 0.85 nmol × 10(6) cell(-1) min(-1), respectively. Using valves built into the chip, the perfusion solution was switched to add 20 μM isoproterenol, a β-adrenergic agonist, which stimulates the release of glycerol and fatty acids in adipocytes. This manipulation resulted in a rapid and stable 1.5- to 6.0-fold increase of non-esterified fatty acid (NEFA) and glycerol. The ratio of NEFA:glycerol released increased with adipocyte age. These experiments illustrate the potential for performing multiple real-time assays on cells in culture using microfluidic devices.
Collapse
Affiliation(s)
- Colleen E. Dugan
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - William P. Cawthorn
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Ormond A. MacDougald
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Robert T. Kennedy
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109, USA
| |
Collapse
|
46
|
Abstract
In adipocytes the hydrolysis of TAG to produce fatty acids and glycerol under fasting conditions or times of elevated energy demands is tightly regulated by neuroendocrine signals, resulting in the activation of lipolytic enzymes. Among the classic regulators of lipolysis, adrenergic stimulation and the insulin-mediated control of lipid mobilisation are the best known. Initially, hormone-sensitive lipase (HSL) was thought to be the rate-limiting enzyme of the first lipolytic step, while we now know that adipocyte TAG lipase is the key enzyme for lipolysis initiation. Pivotal, previously unsuspected components have also been identified at the protective interface of the lipid droplet surface and in the signalling pathways that control lipolysis. Perilipin, comparative gene identification-58 (CGI-58) and other proteins of the lipid droplet surface are currently known to be key regulators of the lipolytic machinery, protecting or exposing the TAG core of the droplet to lipases. The neuroendocrine control of lipolysis is prototypically exerted by catecholaminergic stimulation and insulin-induced suppression, both of which affect cyclic AMP levels and hence the protein kinase A-mediated phosphorylation of HSL and perilipin. Interestingly, in recent decades adipose tissue has been shown to secrete a large number of adipokines, which exert direct effects on lipolysis, while adipocytes reportedly express a wide range of receptors for signals involved in lipid mobilisation. Recently recognised mediators of lipolysis include some adipokines, structural membrane proteins, atrial natriuretic peptides, AMP-activated protein kinase and mitogen-activated protein kinase. Lipolysis needs to be reanalysed from the broader perspective of its specific physiological or pathological context since basal or stimulated lipolytic rates occur under diverse conditions and by different mechanisms.
Collapse
|
47
|
Arrese EL, Saudale FZ, Soulages JL. Lipid Droplets as Signaling Platforms Linking Metabolic and Cellular Functions. Lipid Insights 2014; 7:7-16. [PMID: 25221429 PMCID: PMC4161058 DOI: 10.4137/lpi.s11128] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The main cells of the adipose tissue of animals, adipocytes, are characterized by the presence of large cytosolic lipid droplets (LDs) that store triglyceride (TG) and cholesterol. However, most cells have LDs and the ability to store lipids. LDs have a well-known central role in storage and provision of fatty acids and cholesterol. However, the complexity of the regulation of lipid metabolism on the surface of the LDs is still a matter of intense study. Beyond this role, a number of recent studies have suggested that LDs have major functions in other cellular processes, such as protein storage and degradation, infection, and immunity. Thus, our perception of LDs has been radically transformed from simple globules of fat to highly dynamic organelles of unexpected complexity. Here, we compiled some recent evidence supporting the emerging view that LDs act as platforms connecting a number of relevant metabolic and cellular functions.
Collapse
Affiliation(s)
- Estela L Arrese
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
| | - Fredy Z Saudale
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
| | - Jose L Soulages
- Department of Biochemistry and Molecular Biology; Oklahoma State University; Stillwater, OK, 74078, USA
| |
Collapse
|
48
|
Abstract
PURPOSE OF REVIEW With the realization that lipid droplets are not merely inert fat storage organelles, but highly dynamic and actively involved in cellular lipid homeostasis, there has been an increased interest in lipid droplet biology. Recent studies have begun to unravel the roles that lipid dropletss play in cellular physiology and provide insights into the mechanisms by which lipid droplets contribute to cellular homeostasis. This review provides a summary of these recent publications on lipid droplet metabolism. RECENT FINDINGS Perilipins have different preferences for associating with triacylglycerol (TAG) or cholesteryl esters, different tissue distributions, and each contributes to lipid metabolism in its unique way. Cell death-inducing DFF45-like effector proteins are not only involved in lipid droplet expansion, but also in the cellular response to stress and lipid secretion. Lipid droplets undergo an active cycle of lipolysis and re-esterification to form microlipid droplets. TAG synthesis for lipid droplet formation and expansion occurs in the endoplasmic reticulum and on lipid droplets, and TAG transfers between lipid droplets during lipid droplet fusion. Lipid droplets interact with the endoplasmic reticulum and mitochondria to facilitate lipid transfer, lipid droplet expansion, and metabolism. SUMMARY Lipid droplets are dynamically active, responding to changes in cellular physiology, as well as interacting with cytosolic proteins and other organelles to control lipid homeostasis.
Collapse
Affiliation(s)
- Victor K Khor
- aVeterans Affairs Palo Alto Healthcare System, Palo Alto bDivision of Endocrinology, Stanford University, Stanford, California, USA
| | | | | |
Collapse
|
49
|
Hashimoto T, Yokokawa T, Endo Y, Iwanaka N, Higashida K, Taguchi S. Modest hypoxia significantly reduces triglyceride content and lipid droplet size in 3T3-L1 adipocytes. Biochem Biophys Res Commun 2013; 440:43-9. [DOI: 10.1016/j.bbrc.2013.09.034] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 09/05/2013] [Indexed: 12/26/2022]
|
50
|
Tanaka T, Kuroda K, Ikeda M, Kato N, Shimizu K, Makishima M. Direct targeting of proteins to lipid droplets demonstrated by time-lapse live cell imaging. J Biosci Bioeng 2013; 116:620-3. [PMID: 23742748 DOI: 10.1016/j.jbiosc.2013.05.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 05/01/2013] [Accepted: 05/02/2013] [Indexed: 12/01/2022]
Abstract
A protein that specifically targets lipid droplets (LDs) was created by connecting two domains of nonstructural protein 4B containing amphipathic helices from hepatitis C virus. We demonstrated its direct targeting and accumulation to the LD surface by time-lapse live cell imaging, comparable to those observed with adipose differentiation-related protein.
Collapse
Affiliation(s)
- Torahiko Tanaka
- Division of Biochemistry, Department of Biomedical Sciences, Nihon University School of Medicine, 30-1 Oyaguchi-kamimachi, Itabashi-ku, Tokyo 173-8610, Japan.
| | | | | | | | | | | |
Collapse
|