1
|
Snarski P, Ghimire J, Savkovic SD. FOXO3: at the crossroads of metabolic, inflammatory, and tumorigenic remodeling in the colon. Am J Physiol Gastrointest Liver Physiol 2024; 326:G247-G251. [PMID: 38193202 PMCID: PMC11211034 DOI: 10.1152/ajpgi.00201.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/19/2023] [Accepted: 12/23/2023] [Indexed: 01/10/2024]
Abstract
The Forkhead box O3 (FOXO3) transcription factor regulates the expression of genes critical for diverse cellular functions in homeostasis. Diminished FOXO3 activity is associated with human diseases such as obesity, metabolic diseases, inflammatory diseases, and cancer. In the mouse colon, FOXO3 deficiency leads to an inflammatory immune landscape and dysregulated molecular pathways, which, under various insults, exacerbates inflammation and tumor burden, mimicking characteristics of human diseases. This deficiency also results in dysregulated lipid metabolism, and consequently, the accumulation of intracellular lipid droplets (LDs) in colonic epithelial cells and infiltrated immune cells. FOXO3 and LDs form a self-reinforcing negative regulatory loop in colonic epithelial cells, neutrophils, and macrophages, which is associated with inflammatory bowel disease and colon cancer, particularly in the context of obesity.
Collapse
Affiliation(s)
- Patricia Snarski
- Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States
| | - Jenisha Ghimire
- Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States
| | - Suzana D Savkovic
- Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana, United States
| |
Collapse
|
2
|
Mallick R, Basak S, Das RK, Banerjee A, Paul S, Pathak S, Duttaroy AK. Fatty Acids and their Proteins in Adipose Tissue Inflammation. Cell Biochem Biophys 2024; 82:35-51. [PMID: 37794302 PMCID: PMC10867084 DOI: 10.1007/s12013-023-01185-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2023] [Indexed: 10/06/2023]
Abstract
Chronic low-grade adipose tissue inflammation is associated with metabolic disorders. Inflammation results from the intertwined cross-talks of pro-inflammatory and anti-inflammatory pathways in the immune response of adipose tissue. In addition, adipose FABP4 levels and lipid droplet proteins are involved in systemic and tissue inflammation. Dysregulated adipocytes help infiltrate immune cells derived from bone marrow responsible for producing cytokines and chemokines. When adipose tissue expands in excess, adipocyte exhibits increased secretion of adipokines and is implicated in metabolic disturbances due to the release of free fatty acids. This review presents an emerging concept in adipose tissue fat metabolism, fatty acid handling and binding proteins, and lipid droplet proteins and their involvement in inflammatory disorders.
Collapse
Affiliation(s)
- Rahul Mallick
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Sanjay Basak
- Molecular Biology Division, ICMR-National Institute of Nutrition, Indian Council of Medical Research, Hyderabad, India
| | - Ranjit K Das
- Department of Health and Biomedical Sciences, University of Texas Rio Grande Valley, Brownsville, TX, USA
| | - Antara Banerjee
- Chettinad Academy of Research and Education (CARE), Chettinad Hospital and Research Institute (CHRI), Department of Medical Biotechnology, Faculty of Allied Health Sciences, Chennai, India
| | - Sujay Paul
- Tecnologico de Monterrey, School of Engineering and Sciences, Campus Queretaro, Av. Epigmenio Gonzalez, No. 500 Fracc, San Pablo, Queretaro, 76130, Mexico
| | - Surajit Pathak
- Chettinad Academy of Research and Education (CARE), Chettinad Hospital and Research Institute (CHRI), Department of Medical Biotechnology, Faculty of Allied Health Sciences, Chennai, India
| | - Asim K Duttaroy
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, POB 1046 Blindern, Oslo, Norway.
| |
Collapse
|
3
|
Nisticò C, Chiarella E. An Overview on Lipid Droplets Accumulation as Novel Target for Acute Myeloid Leukemia Therapy. Biomedicines 2023; 11:3186. [PMID: 38137407 PMCID: PMC10741140 DOI: 10.3390/biomedicines11123186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 11/28/2023] [Accepted: 11/28/2023] [Indexed: 12/24/2023] Open
Abstract
Metabolic reprogramming is a key alteration in tumorigenesis. In cancer cells, changes in metabolic fluxes are required to cope with large demands on ATP, NADPH, and NADH, as well as carbon skeletons. In particular, dysregulation in lipid metabolism ensures a great energy source for the cells and sustains cell membrane biogenesis and signaling molecules, which are necessary for tumor progression. Increased lipid uptake and synthesis results in intracellular lipid accumulation as lipid droplets (LDs), which in recent years have been considered hallmarks of malignancies. Here, we review current evidence implicating the biogenesis, composition, and functions of lipid droplets in acute myeloid leukemia (AML). This is an aggressive hematological neoplasm originating from the abnormal expansion of myeloid progenitor cells in bone marrow and blood and can be fatal within a few months without treatment. LD accumulation positively correlates with a poor prognosis in AML since it involves the activation of oncogenic signaling pathways and cross-talk between the tumor microenvironment and leukemic cells. Targeting altered LD production could represent a potential therapeutic strategy in AML. From this perspective, we discuss the main inhibitors tested in in vitro AML cell models to block LD formation, which is often associated with leukemia aggressiveness and which may find clinical application in the future.
Collapse
Affiliation(s)
- Clelia Nisticò
- Candiolo Cancer Institute, FPO-IRCCS, Department of Oncology, University of Torino, 10124 Candiolo, Italy
| | - Emanuela Chiarella
- Laboratory of Molecular Haematopoiesis and Stem Cell Biology, Department of Experimental and Clinical Medicine, University “Magna Græcia”, 88100 Catanzaro, Italy
| |
Collapse
|
4
|
Sun Y, Heng J, Liu F, Zhang S, Liu P. Isolation and proteomic study of fish liver lipid droplets. BIOPHYSICS REPORTS 2023; 9:120-133. [PMID: 38028150 PMCID: PMC10648235 DOI: 10.52601/bpr.2023.230004] [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: 02/26/2023] [Accepted: 06/02/2023] [Indexed: 12/01/2023] Open
Abstract
Lipid droplets (LDs) are a neutral lipid storage organelle that is conserved in almost all species. Excessive storage of neutral lipids in LDs is directly associated with many metabolic syndromes. Zebrafish is a better model animal for the study of LD biology due to its transparent embryonic stage compared to other organisms. However, the study of LDs in fish has been difficult due to the lack of specific LD marker proteins and the limitation of purification technology. In this paper, the purification and proteomic analysis of liver LDs of fish including zebrafish and Carassius auratus were performed for the first time. 259 and 267 proteins were identified respectively. Besides most of the identified proteins were reported in previous LD proteomes of mammals, indicating the similarity between mammal and fish LDs. We also identified many unique proteins of liver LDs in fish that are involved in the regulation of LD dynamics. Through morphological and biochemical analysis, we found that the marker protein Plin2 of zebrafish LD was located on LDs in Huh7 cells. These results will facilitate further study of LDs in fish and liver metabolic diseases using fish as a model animal.
Collapse
Affiliation(s)
- Yuwei Sun
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Heng
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Institute of Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Feng Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Institute of Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuyan Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
5
|
Bresgen N, Kovacs M, Lahnsteiner A, Felder TK, Rinnerthaler M. The Janus-Faced Role of Lipid Droplets in Aging: Insights from the Cellular Perspective. Biomolecules 2023; 13:912. [PMID: 37371492 PMCID: PMC10301655 DOI: 10.3390/biom13060912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 05/22/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
It is widely accepted that nine hallmarks-including mitochondrial dysfunction, epigenetic alterations, and loss of proteostasis-exist that describe the cellular aging process. Adding to this, a well-described cell organelle in the metabolic context, namely, lipid droplets, also accumulates with increasing age, which can be regarded as a further aging-associated process. Independently of their essential role as fat stores, lipid droplets are also able to control cell integrity by mitigating lipotoxic and proteotoxic insults. As we will show in this review, numerous longevity interventions (such as mTOR inhibition) also lead to strong accumulation of lipid droplets in Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, and mammalian cells, just to name a few examples. In mammals, due to the variety of different cell types and tissues, the role of lipid droplets during the aging process is much more complex. Using selected diseases associated with aging, such as Alzheimer's disease, Parkinson's disease, type II diabetes, and cardiovascular disease, we show that lipid droplets are "Janus"-faced. In an early phase of the disease, lipid droplets mitigate the toxicity of lipid peroxidation and protein aggregates, but in a later phase of the disease, a strong accumulation of lipid droplets can cause problems for cells and tissues.
Collapse
Affiliation(s)
- Nikolaus Bresgen
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria; (N.B.)
| | - Melanie Kovacs
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria; (N.B.)
| | - Angelika Lahnsteiner
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria; (N.B.)
| | - Thomas Klaus Felder
- Department of Laboratory Medicine, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Mark Rinnerthaler
- Department of Biosciences and Medical Biology, Paris-Lodron University Salzburg, 5020 Salzburg, Austria; (N.B.)
| |
Collapse
|
6
|
Yang D, Wang X, Zhang L, Fang Y, Zheng Q, Liu X, Yu W, Chen S, Ying J, Hua F. Lipid metabolism and storage in neuroglia: role in brain development and neurodegenerative diseases. Cell Biosci 2022; 12:106. [PMID: 35831869 PMCID: PMC9277953 DOI: 10.1186/s13578-022-00828-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/05/2022] [Indexed: 11/13/2022] Open
Abstract
The importance of neuroglia in maintaining normal brain function under physiological and pathological conditions has been supported by growing evidence in recent years. The most important issues regarding glial metabolism and function include the cooperation between glial populations and neurons, morphological and functional changes in pathological states, and the role in the onset and progression of neurodegenerative diseases. Although lipid accumulation and further lipid droplet production in neurodegenerative disease brain models have been observed for a long time, the dynamic development of brain lipid droplet research in recent years suggests its role in the development and progression of neurodegenerative diseases was previously underestimated. First recognized as organelles of lipid storage, lipid droplets (LDs) have emerged as an important organelle in metabolic diseases, inflammation, and host defense. Dynamic changes in lipid metabolism within neurons and glial cells resulting in lipid accumulation and lipid droplet formation are present in brain models of various neurodegenerative diseases, yet their role in the brain remains largely unexplored. This paper first reviews the metabolism and accumulation of several major lipids in the brain and discusses the regulation of lipid accumulation in different types of brain cells. We explore the potential role of intracellular lipid accumulation in the pathogenesis of neurodegeneration, starting from lipid metabolism and LDs biogenesis in glial cells, and discuss several pathological factors that promote lipid droplet formation, mainly focusing on oxidative stress, energy metabolism and glial cell-neuron coupling, which are closely related to the etiology and progression of neurodegenerative diseases. Finally, the directions and challenges of intracellular lipid metabolism in glial cells in neurodegeneration are discussed.
Collapse
|
7
|
Zhou X, Matskova L, Zheng S, Wang X, Wang Y, Xiao X, Mo Y, Wölke M, Li L, Zheng Q, Huang G, Zhang Z, Ernberg I. Mechanisms of Anergic Inflammatory Response in Nasopharyngeal Carcinoma Cells Despite Ubiquitous Constitutive NF-κB Activation. Front Cell Dev Biol 2022; 10:861916. [PMID: 35938161 PMCID: PMC9353648 DOI: 10.3389/fcell.2022.861916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 06/15/2022] [Indexed: 11/29/2022] Open
Abstract
Commensal microbes cross talk with their colonized mucosa. We show that microbes and their cell wall components induce an inflammatory response in cultured human mucosal cells derived from the nonmalignant nasopharyngeal epithelium (NNE) cells in vitro. NNE cells show significant induction of NF-κB with nuclear shuttling and inflammatory gene response when exposed to Gram-positive bacteria (streptococci) or peptidoglycan (PGN), a component of the Gram-positive bacterial cell wall. This response is abrogated in nasopharyngeal carcinoma (NPC)–derived cell lines. The inflammatory response induced by NF-κB signaling was blocked at two levels in the tumor-derived cells. We found that NF-κB was largely trapped in lipid droplets (LDs) in the cytoplasm of the NPC-derived cells, while the increased expression of lysine-specific histone demethylase 1 (LSD1, a repressive nuclear factor) reduces the response mediated by remaining NF-κB at the promoters responding to inflammatory stimuli. This refractory response in NPC cells might be a consequence of long-term exposure to microbes in vivo during carcinogenic progression. It may contribute to the decreased antitumor immune responses in NPC, among others despite heavy T-helper cell infiltration, and thus facilitate tumor progression.
Collapse
Affiliation(s)
- Xiaoying Zhou
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
- Life Science Institute, Guangxi Medical University, Nanning, China
- Key Laboratory of Early Prevention and Treatment for Regional High-Frequency Tumor (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Liudmila Matskova
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Shixing Zheng
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, Fudan University, Shanghai, China
| | - Xiaoxia Wang
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Yifang Wang
- Life Science Institute, Guangxi Medical University, Nanning, China
- Key Laboratory of Early Prevention and Treatment for Regional High-Frequency Tumor (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Xue Xiao
- Department of Otolaryngology-Head and Neck Surgery, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Yingxi Mo
- Department of Research, Affiliated Tumor Hospital of Guangxi Medical University, Nanning, China
| | - Marleen Wölke
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - Limei Li
- Key Laboratory of Early Prevention and Treatment for Regional High-Frequency Tumor (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Qian Zheng
- Life Science Institute, Guangxi Medical University, Nanning, China
- Key Laboratory of Early Prevention and Treatment for Regional High-Frequency Tumor (Guangxi Medical University), Ministry of Education, Nanning, China
| | - Guangwu Huang
- Key Laboratory of Early Prevention and Treatment for Regional High-Frequency Tumor (Guangxi Medical University), Ministry of Education, Nanning, China
- Department of Otolaryngology-Head and Neck Surgery, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Zhe Zhang
- Key Laboratory of Early Prevention and Treatment for Regional High-Frequency Tumor (Guangxi Medical University), Ministry of Education, Nanning, China
- ENT Institute and Department of Otorhinolaryngology, Eye and ENT Hospital, Fudan University, Shanghai, China
| | - Ingemar Ernberg
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
- *Correspondence: Ingemar Ernberg,
| |
Collapse
|
8
|
Lipid metabolism and neutrophil function. Cell Immunol 2022; 377:104546. [DOI: 10.1016/j.cellimm.2022.104546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 05/12/2022] [Accepted: 05/19/2022] [Indexed: 11/22/2022]
|
9
|
Antunes P, Cruz A, Barbosa J, Bonifácio VDB, Pinto SN. Lipid Droplets in Cancer: From Composition and Role to Imaging and Therapeutics. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27030991. [PMID: 35164256 PMCID: PMC8840564 DOI: 10.3390/molecules27030991] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/26/2022] [Accepted: 01/31/2022] [Indexed: 12/11/2022]
Abstract
Cancer is the second most common cause of death worldwide, having its origin in the abnormal growth of cells. Available chemotherapeutics still present major drawbacks, usually associated with high toxicity and poor distribution, with only a small fraction of drugs reaching the tumour sites. Thus, it is urgent to develop novel therapeutic strategies. Cancer cells can reprogram their lipid metabolism to sustain uncontrolled proliferation, and, therefore, accumulate a higher amount of lipid droplets (LDs). LDs are cytoplasmic organelles that store neutral lipids and are hypothesized to sequester anti-cancer drugs, leading to reduced efficacy. Thus, the increased biogenesis of LDs in neoplastic conditions makes them suitable targets for anticancer therapy and for the development of new dyes for cancer cells imaging. In recent years, cancer nanotherapeutics offered some exciting possibilities, including improvement tumour detection and eradication. In this review we summarize LDs biogenesis, structure and composition, and highlight their role in cancer theranostics.
Collapse
Affiliation(s)
- Patrícia Antunes
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; (P.A.); (A.C.); (J.B.)
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Adriana Cruz
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; (P.A.); (A.C.); (J.B.)
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - José Barbosa
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; (P.A.); (A.C.); (J.B.)
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Vasco D. B. Bonifácio
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; (P.A.); (A.C.); (J.B.)
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
- Bioengineering Department, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
- Correspondence: (V.D.B.B.); (S.N.P.)
| | - Sandra N. Pinto
- iBB-Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; (P.A.); (A.C.); (J.B.)
- Associate Laboratory i4HB-Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
- Correspondence: (V.D.B.B.); (S.N.P.)
| |
Collapse
|
10
|
Pereira-Dutra FS, Bozza PT. Lipid droplets diversity and functions in inflammation and immune response. Expert Rev Proteomics 2021; 18:809-825. [PMID: 34668810 DOI: 10.1080/14789450.2021.1995356] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Lipid droplets (LDs) are dynamic and evolutionary conserved lipid-enriched organelles composed of a core of neutral lipids surrounded by a monolayer of phospholipids associated with a diverse array of proteins that are cell- and stimulus-regulated. Far beyond being simply a deposit of neutral lipids, accumulating evidence demonstrate that LDs act as spatial and temporal local for lipid and protein compartmentalization and signaling organization. AREAS COVERED This review focuses on the progress in our understanding of LD protein diversity and LD functions in the context of cell signaling and immune responses, highlighting the relationship between LD composition with the multiple roles of this organelle in immunometabolism, inflammation and host-response to infection. EXPERT OPINION LDs are essential platforms for various cellular processes, including metabolic regulation, cell signaling, and immune responses. The functions of LD in infection and inflammatory disease are associated with the dynamic and complexity of their proteome. Our contemporary view place LDs as critical regulators of different inflammatory and infectious diseases and key markers of leukocyte activation.
Collapse
Affiliation(s)
- Filipe S Pereira-Dutra
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Patrícia T Bozza
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| |
Collapse
|
11
|
Lipid Droplet Accumulation Independently Predicts Poor Clinical Prognosis in High-Grade Serous Ovarian Carcinoma. Cancers (Basel) 2021; 13:cancers13205251. [PMID: 34680399 PMCID: PMC8533764 DOI: 10.3390/cancers13205251] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 10/16/2021] [Indexed: 12/24/2022] Open
Abstract
Simple Summary High-grade serous carcinoma (HGSOC) is the most aggressive subtype of ovarian cancer and accounts for the vast majority of advanced stage cases. Intracellular accumulation of lipids as lipid droplets has been recognized as one of the characteristics of cancers and implicated in poor prognosis of several cancers, such as human melanomas. Here, we investigated the relationship between prognosis and lipid accumulation in HGSOC, and found that enhanced lipid accumulation in HGSOC tissues significantly correlated with poor prognosis. In cell-based assays with human ovarian cancer cells, we provide evidence that aerobic glycolysis, which is one of the characteristic metabolic abnormalities in cancer, induced lipid accumulation within cancer cells and targeting the lipid accumulation could suppress cancer cell proliferation. Thus, our results propose abnormal lipid accumulation as a negative indicator of HGSOC prognosis and a novel therapeutic target. Abstract High-grade serous ovarian carcinoma (HGSOC) is an epithelial cancer that accounts for most ovarian cancer deaths. Metabolic abnormalities such as extensive aerobic glycolysis and aberrant lipid metabolism are well-known characteristics of cancer cells. Indeed, accumulation of lipid droplets (LDs) in certain types of malignant tumors has been known for more than 50 years. Here, we investigated the correlation between LD accumulation and clinical prognosis. In 96 HGSOC patients, we found that high expression of the LD marker adipophilin was associated with poor progression-free and overall survival (p = 0.0022 and p = 0.014, respectively). OVCAR-3 ovarian carcinoma cells accumulated LDs in a glucose-dependent manner, which suggested the involvement of aerobic glycolysis and subsequently enhanced lipogenesis, with a result being LD accumulation. The acyl-CoA: cholesterol acyltransferase 1 inhibitor K604 and the hydroxymethylglutaryl-CoA reductase inhibitor pitavastatin blocked LD accumulation in OVCAR-3 cells and reduced phosphorylation of the survival-related kinases Akt and ERK1/2, both of which have been implicated in malignancy. Our cell-based assays thus suggested that enhanced aerobic glycolysis resulted in LD accumulation and activation of survival-related kinases. Overall, our results support the idea that cancers with lipogenic phenotypes are associated with poor clinical prognosis, and we suggest that adipophilin may serve as an independent indicator of a poor prognosis in HGSOC.
Collapse
|
12
|
Lipid droplet biogenesis and COX-2 pathway activation are triggered by Barrett's esophagus and adenocarcinoma, but not esophageal squamous cell carcinoma risk factors. Sci Rep 2021; 11:981. [PMID: 33441691 PMCID: PMC7807011 DOI: 10.1038/s41598-020-80035-4] [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: 12/11/2019] [Accepted: 11/24/2020] [Indexed: 12/09/2022] Open
Abstract
Esophageal cancer (EC) is an aggressive disease, presenting two main histological subtypes: adenocarcinoma (EAC) and squamous cell carcinoma (ESCC). The two EC subtypes widely differ concerning virtually all factors. ESCC development is mainly associated with tobacco and alcohol abuse, whereas obesity and chronic gastroesophageal reflux disease (GERD) are important risk factors not only for EAC, but also for for Barrett’s esophagus (BE), an intestinal metaplasia that precedes EAC. Obesity triggers ectopic lipid droplets (LD) accumulation in non-adipose tissues. LD are organelles involved in cell metabolism, signaling, proliferation and production of inflammatory mediators. Therefore, the aim of this work was to investigate LD occurrence and role in EC. This study shows progressive LD levels increase along EAC development, in esophageal samples from non-obese through obese individuals, as well as BE, and EAC patients, whereas no significant changes were observed in ESCC samples, when compared to non-tumor samples. Additionally, in order to mimic BE and EAC risk factors exposure, a non-tumor esophageal cell line was incubated with oleic acid (OA) and acidified medium and/or deoxycholic acid (DCA), revealing a significant increment in LD amount as well as in COX-2 and CXCL-8 expression, and in IL-8 secretion. Further, COX-2 expression and LD amount presented a significant positive correlation and were detected co-localized in EAC, but not in ESCC, suggesting that LD may be the site for eicosanoid production in EAC. In conclusion, this study shows that obesity, and BE- and EAC-associated inflammatory stimuli result in a gradual increase of LD, that may be responsible for orchestrating inflammatory mediators’ production and/or action, thus contributing to BE and EAC genesis and progression.
Collapse
|
13
|
Ogasawara Y, Cheng J, Tatematsu T, Uchida M, Murase O, Yoshikawa S, Ohsaki Y, Fujimoto T. Long-term autophagy is sustained by activation of CCTβ3 on lipid droplets. Nat Commun 2020; 11:4480. [PMID: 32900992 PMCID: PMC7479109 DOI: 10.1038/s41467-020-18153-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 08/07/2020] [Indexed: 12/12/2022] Open
Abstract
Macroautophagy initiates by formation of isolation membranes, but the source of phospholipids for the membrane biogenesis remains elusive. Here, we show that autophagic membranes incorporate newly synthesized phosphatidylcholine, and that CTP:phosphocholine cytidylyltransferase β3 (CCTβ3), an isoform of the rate-limiting enzyme in the Kennedy pathway, plays an essential role. In starved mouse embryo fibroblasts, CCTβ3 is initially recruited to autophagic membranes, but upon prolonged starvation, it concentrates on lipid droplets that are generated from autophagic degradation products. Omegasomes and isolation membranes emanate from around those lipid droplets. Autophagy in prolonged starvation is suppressed by knockdown of CCTβ3 and is enhanced by its overexpression. This CCTβ3-dependent mechanism is also present in U2OS, an osteosarcoma cell line, and autophagy and cell survival in starvation are decreased by CCTβ3 depletion. The results demonstrate that phosphatidylcholine synthesis through CCTβ3 activation on lipid droplets is crucial for sustaining autophagy and long-term cell survival.
Collapse
Affiliation(s)
- Yuta Ogasawara
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo, Tokyo, 113-8421, Japan
| | - Jinglei Cheng
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Tsuyako Tatematsu
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Misaki Uchida
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Omi Murase
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Shogo Yoshikawa
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Yuki Ohsaki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showa, Nagoya, 466-8550, Japan
| | - Toyoshi Fujimoto
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo, Tokyo, 113-8421, Japan.
| |
Collapse
|
14
|
Jin C, Yuan P. Implications of lipid droplets in lung cancer: Associations with drug resistance. Oncol Lett 2020; 20:2091-2104. [PMID: 32782526 PMCID: PMC7399769 DOI: 10.3892/ol.2020.11769] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 05/27/2020] [Indexed: 12/12/2022] Open
Abstract
Cancer cells usually show different metabolic patterns compared with healthy cells due to the reprogramming of metabolic processes. The process of lipid metabolism undergoes notable changes, leading to the accumulation of lipid droplets in cells. Additionally, this phenotype is considered an important marker of cancer cells. Lipid droplets are a highly dynamic type of organelle in the cell, which is composed of a neutral lipid core, a monolayer phospholipid membrane and lipid droplet-related proteins. Lipid droplets are involved in several biological processes, including cell proliferation, apoptosis, lipid metabolism, stress, immunity, signal transduction and protein trafficking. Epidermal growth factor receptor (EGFR)-activating mutations are currently the most effective therapeutic targets for non-small cell lung cancer. Several EGFR tyrosine kinase inhibitors (EGFR-TKIs) that target these mutations, including gefitinib, erlotinib, afatinib and osimertinib, have been widely used clinically. However, the development of acquired resistance has a major impact on the efficacy of these drugs. A number of previous studies have reported that the expression of lipid droplets in the tumor tissues of patients with lung cancer are elevated, whereas the association between elevated numbers of lipid droplets and drug resistance has received little attention. The present review describes the potential association between lipid droplets and drug resistance. Furthermore, the mechanisms and implications of lipid droplet accumulation in cancer cells are analyzed, as wells as the mechanism by which lipid droplets suppress endoplasmic reticulum stress and apoptosis, which are essential for the development and treatment of lung cancer.
Collapse
Affiliation(s)
- Chunlai Jin
- Department of Surgery, First People's Hospital of Jinan, Jinan, Shandong 250011, P.R. China
| | - Peng Yuan
- Department of Surgery, First People's Hospital of Jinan, Jinan, Shandong 250011, P.R. China
| |
Collapse
|
15
|
Cruz ALS, Barreto EDA, Fazolini NPB, Viola JPB, Bozza PT. Lipid droplets: platforms with multiple functions in cancer hallmarks. Cell Death Dis 2020; 11:105. [PMID: 32029741 PMCID: PMC7005265 DOI: 10.1038/s41419-020-2297-3] [Citation(s) in RCA: 244] [Impact Index Per Article: 61.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 01/16/2020] [Accepted: 01/20/2020] [Indexed: 02/06/2023]
Abstract
Lipid droplets (also known as lipid bodies) are lipid-rich, cytoplasmic organelles that play important roles in cell signaling, lipid metabolism, membrane trafficking, and the production of inflammatory mediators. Lipid droplet biogenesis is a regulated process, and accumulation of these organelles within leukocytes, epithelial cells, hepatocytes, and other nonadipocyte cells is a frequently observed phenotype in several physiologic or pathogenic situations and is thoroughly described during inflammatory conditions. Moreover, in recent years, several studies have described an increase in intracellular lipid accumulation in different neoplastic processes, although it is not clear whether lipid droplet accumulation is directly involved in the establishment of these different types of malignancies. This review discusses current evidence related to the biogenesis, composition and functions of lipid droplets related to the hallmarks of cancer: inflammation, cell metabolism, increased proliferation, escape from cell death, and hypoxia. Moreover, the potential of lipid droplets as markers of disease and targets for novel anti-inflammatory and antineoplastic therapies will be discussed.
Collapse
Affiliation(s)
- André L S Cruz
- Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil
- Laboratory of Physiopathology, Polo Novo Cavaleiros, Federal University of Rio De Janeiro (UFRJ), Macaé, Brazil
| | - Ester de A Barreto
- Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil
| | - Narayana P B Fazolini
- Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil
| | - João P B Viola
- Program of Immunology and Tumor Biology, Brazilian National Cancer Institute (INCA), Rio de Janeiro, Brazil.
| | - Patricia T Bozza
- Laboratory of Immunopharmacology, Oswaldo Cruz Institute, FIOCRUZ, Rio de Janeiro, Brazil.
| |
Collapse
|
16
|
Inoh Y, Tsuchiya Y, Nakanishi Y, Yokawa S, Furuno T. Involvement of intracellular caveolin-1 distribution in the suppression of antigen-induced mast cell activation by cationic liposomes. Cell Biol Int 2020; 44:1068-1075. [PMID: 31889352 DOI: 10.1002/cbin.11297] [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: 09/06/2019] [Accepted: 12/28/2019] [Indexed: 11/10/2022]
Abstract
Cationic liposomes are commonly used as vectors to effectively introduce foreign genes into target cells. In another function, we recently showed that cationic liposomes bound to the mast cell surface suppress the degranulation induced by the cross-linking of high-affinity immunoglobulin E receptor in a time- and dose-dependent manner. This suppression is mediated by the impairment of the sustained level of intracellular Ca2+ concentration ([Ca2+ ]i ) via the inhibition of store-operated Ca2+ entry. Further, we revealed that the mechanism underlying an impaired [Ca2+ ]i increase is the inhibition of the activation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway. Yet, how cationic liposomes inhibit the PI3K-Akt pathway is still unclear. Here, we focused on caveolin-1, a major component of caveolae, which is reported to be involved in the activation of the PI3K-Akt pathway in various cell lines. In this study, we showed that caveolin-1 translocated from the cytoplasm to the plasma membrane after the activation of mast cells and colocalized with the p85 subunit of PI3K, which seemed to be essential for PI3K activity. Meanwhile, cationic liposomes suppressed the translocation of caveolin-1 to the plasma membrane and the colocalization of caveolin-1 with PI3K p85 also at the plasma membrane. This finding provides new information for the development of therapies using cationic liposomes against allergies.
Collapse
Affiliation(s)
- Yoshikazu Inoh
- School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan
| | - Yuuki Tsuchiya
- School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan
| | - Yokiko Nakanishi
- School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan
| | - Satoru Yokawa
- School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan
| | - Tadahide Furuno
- School of Pharmacy, Aichi Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya, 464-8650, Japan
| |
Collapse
|
17
|
Abramczyk H, Imiela A, Brożek-Płuska B, Kopeć M, Surmacki J, Śliwińska A. Aberrant Protein Phosphorylation in Cancer by Using Raman Biomarkers. Cancers (Basel) 2019; 11:E2017. [PMID: 31847192 PMCID: PMC6966530 DOI: 10.3390/cancers11122017] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/03/2019] [Accepted: 12/11/2019] [Indexed: 12/30/2022] Open
Abstract
(1) Background: Novel methods are required for analysing post-translational modifications of protein phosphorylation by visualizing biochemical landscapes of proteins in human normal and cancerous tissues and cells. (2) Methods: A label-free Raman method is presented for detecting spectral changes that arise in proteins due to phosphorylation in the tissue of human breasts, small intestines, and brain tumours, as well as in the normal human astrocytes and primary glioblastoma U-87 MG cell lines. Raman spectroscopy and Raman imaging are effective tools for monitoring and analysing the vibrations of functional groups involved in aberrant phosphorylation in cancer without any phosphorecognition of tag molecules. (3) Results: Our results based on 35 fresh human cancer and normal tissues prove that the aberrant tyrosine phosphorylation monitored by the unique spectral signatures of Raman vibrations is a universal characteristic in the metabolic regulation in different types of cancers. Overexpressed tyrosine phosphorylation in the human breast, small intestine and brain tissues and in the human primary glioblastoma U-87 MG cell line was monitored by using Raman biomarkers. (4) We showed that the bands at 1586 cm-1 and 829 cm-1, corresponding to phosphorylated tyrosine, play a pivotal role as a Raman biomarker of the phosphorylation status in aggressive cancers. We found that the best Raman biomarker of phosphorylation is the 1586/829 ratio showing the statistical significance at p Values of ≤ 0.05. (5) Conclusions: Raman spectroscopy and imaging have the potential to be used as screening functional assays to detect phosphorylated target proteins and will help researchers to understand the role of phosphorylation in cellular processes and cancer progression. The abnormal and excessive high level of tyrosine phosphorylation in cancer samples compared with normal samples was found in the cancerous human tissue of breasts, small intestines and brain tumours, as well as in the mitochondria and lipid droplets of the glioblastoma U-87 MG cell line. Detailed insights are presented into the intracellular oncogenic metabolic pathways mediated by phosphorylated tyrosine.
Collapse
Affiliation(s)
- Halina Abramczyk
- Laboratory of Laser Molecular Spectroscopy, Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Wroblewskiego 15, 93-590 Lodz, Poland; (A.I.); (B.B.-P.); (M.K.); (J.S.)
| | - Anna Imiela
- Laboratory of Laser Molecular Spectroscopy, Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Wroblewskiego 15, 93-590 Lodz, Poland; (A.I.); (B.B.-P.); (M.K.); (J.S.)
| | - Beata Brożek-Płuska
- Laboratory of Laser Molecular Spectroscopy, Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Wroblewskiego 15, 93-590 Lodz, Poland; (A.I.); (B.B.-P.); (M.K.); (J.S.)
| | - Monika Kopeć
- Laboratory of Laser Molecular Spectroscopy, Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Wroblewskiego 15, 93-590 Lodz, Poland; (A.I.); (B.B.-P.); (M.K.); (J.S.)
| | - Jakub Surmacki
- Laboratory of Laser Molecular Spectroscopy, Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Wroblewskiego 15, 93-590 Lodz, Poland; (A.I.); (B.B.-P.); (M.K.); (J.S.)
| | - Agnieszka Śliwińska
- Faculty of Medicine, Medical University of Lodz, Chair of Department of Nucleic Acids Biochemistry, Pomorska 251, 92-213 Lodz, Poland;
| |
Collapse
|
18
|
Tan Y, Jin Y, Wu X, Ren Z. PSMD1 and PSMD2 regulate HepG2 cell proliferation and apoptosis via modulating cellular lipid droplet metabolism. BMC Mol Biol 2019; 20:24. [PMID: 31703613 PMCID: PMC6842266 DOI: 10.1186/s12867-019-0141-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 10/29/2019] [Indexed: 01/18/2023] Open
Abstract
Background Obesity and nonalcoholic steatohepatitis (NASH) are well-known risk factors of hepatocellular carcinoma (HCC). The lipid-rich environment enhances the proliferation and metastasis abilities of tumor cells. Previous studies showed the effect of the ubiquitin–proteasome system (UPS) on tumor cell proliferation. However, the underlying mechanism of UPS in regulating the proliferation of lipid-rich tumor cells is not totally clear. Results Here, we identify two proteasome 26S subunits, non-ATPase 1 and 2 (PSMD1 and PSMD2), which regulate HepG2 cells proliferation via modulating cellular lipid metabolism. Briefly, the knockdown of PSMD1 and/or PSMD2 decreases the formation of cellular lipid droplets, the provider of the energy and membrane components for tumor cell proliferation. Mechanically, PSMD1 and PSMD2 regulate the expression of genes related to de novo lipid synthesis via p38-JNK and AKT signaling. Moreover, the high expression of PSMD1 and PSMD2 is significantly correlated with poor prognosis of HCC. Conclusion We demonstrate that PSMD1 and PSMD2 promote the proliferation of HepG2 cells via facilitating cellular lipid droplet accumulation. This study provides a potential therapeutic strategy for the treatment of lipid-rich tumors.
Collapse
Affiliation(s)
- Yanjie Tan
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture & Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China
| | - Yi Jin
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture & Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China
| | - Xiang Wu
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture & Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China
| | - Zhuqing Ren
- Key Laboratory of Swine Genetics and Breeding of Ministry of Agriculture & Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China. .,Bio-Medical Center of Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.
| |
Collapse
|
19
|
Cell Cycle Progression Regulates Biogenesis and Cellular Localization of Lipid Droplets. Mol Cell Biol 2019; 39:MCB.00374-18. [PMID: 30782775 PMCID: PMC6469922 DOI: 10.1128/mcb.00374-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 01/25/2019] [Indexed: 12/19/2022] Open
Abstract
Intracellular lipid accumulation has been associated with a poor prognosis in cancer. We have previously reported the involvement of lipid droplets in cell proliferation in colon cancer cells, suggesting a role for these organelles in cancer development. Intracellular lipid accumulation has been associated with a poor prognosis in cancer. We have previously reported the involvement of lipid droplets in cell proliferation in colon cancer cells, suggesting a role for these organelles in cancer development. In this study, we evaluate the role of lipid droplets in cell cycle regulation and cellular transformation. Cell cycle synchronization of NIH 3T3 cells revealed increased numbers and dispersed distribution of lipid droplets specifically during S phase. Also, the transformed cell lineage NIH 3T3-H-rasV12 showed an accumulation of both lipid droplets and PLIN2 protein above the levels in NIH 3T3 cells. PLIN2 gene overexpression, however, was not able to induce NIH 3T3 cell transformation, disproving the hypothesis that PLIN2 is an oncogene. Furthermore, positive PLIN2 staining was strongly associated with highly proliferative Ki-67-positive areas in human colon adenocarcinoma tissue samples. Taken together, these results indicate that cell cycle progression is associated with tight regulation of lipid droplets, a process that is altered in transformed cells, suggesting the existence of a mechanism that connects cell cycle progression and cell proliferation with lipid accumulation.
Collapse
|
20
|
Johns DG, LeVoci L, Krsmanovic M, Lu M, Hartmann G, Xu S, Wang SP, Chen Y, Bateman T, Blaustein RO. Characterization of Anacetrapib Distribution into the Lipid Droplet of Adipose Tissue in Mice and Human Cultured Adipocytes. Drug Metab Dispos 2018; 47:227-233. [DOI: 10.1124/dmd.118.084525] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 11/29/2018] [Indexed: 01/01/2023] Open
|
21
|
Vallochi AL, Teixeira L, Oliveira KDS, Maya-Monteiro CM, Bozza PT. Lipid Droplet, a Key Player in Host-Parasite Interactions. Front Immunol 2018; 9:1022. [PMID: 29875768 PMCID: PMC5974170 DOI: 10.3389/fimmu.2018.01022] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 04/24/2018] [Indexed: 12/18/2022] Open
Abstract
Lipid droplets (lipid bodies, LDs) are dynamic organelles that have important roles in regulating lipid metabolism, energy homeostasis, cell signaling, membrane trafficking, and inflammation. LD biogenesis, composition, and functions are highly regulated and may vary according to the stimuli, cell type, activation state, and inflammatory environment. Increased cytoplasmic LDs are frequently observed in leukocytes and other cells in a number of infectious diseases. Accumulating evidence reveals LDs participation in fundamental mechanisms of host-pathogen interactions, including cell signaling and immunity. LDs are sources of eicosanoid production, and may participate in different aspects of innate signaling and antigen presentation. In addition, intracellular pathogens evolved mechanisms to subvert host metabolism and may use host LDs, as ways of immune evasion and nutrients source. Here, we review mechanisms of LDs biogenesis and their contributions to the infection progress, and discuss the latest discoveries on mechanisms and pathways involving LDs roles as regulators of the immune response to protozoan infection.
Collapse
Affiliation(s)
- Adriana Lima Vallochi
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| | | | | | | | - Patricia T. Bozza
- Laboratório de Imunofarmacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, Brazil
| |
Collapse
|
22
|
Xu S, Zhang X, Liu P. Lipid droplet proteins and metabolic diseases. Biochim Biophys Acta Mol Basis Dis 2018; 1864:1968-1983. [DOI: 10.1016/j.bbadis.2017.07.019] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/14/2017] [Accepted: 07/19/2017] [Indexed: 12/13/2022]
|
23
|
de Almeida PE, Toledo DAM, Rodrigues GSC, D'Avila H. Lipid Bodies as Sites of Prostaglandin E2 Synthesis During Chagas Disease: Impact in the Parasite Escape Mechanism. Front Microbiol 2018; 9:499. [PMID: 29616011 PMCID: PMC5869919 DOI: 10.3389/fmicb.2018.00499] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/05/2018] [Indexed: 12/22/2022] Open
Abstract
During Chagas disease, the Trypanosoma cruzi can induce some changes in the host cells in order to escape or manipulate the host immune response. The modulation of the lipid metabolism in the host phagocytes or in the parasite itself is one feature that has been observed. The goal of this mini review is to discuss the mechanisms that regulate intracellular lipid body (LB) biogenesis in the course of this parasite infection and their meaning to the pathophysiology of the disease. The interaction host–parasite induces LB (or lipid droplet) formation in a Toll-like receptor 2-dependent mechanism in macrophages and is enhanced by apoptotic cell uptake. Simultaneously, there is a lipid accumulation in the parasite due to the incorporation of host fatty acids. The increase in the LB accumulation during infection is correlated with an increase in the synthesis of PGE2 within the host cells and the parasite LBs. Moreover, the treatment with fatty acid synthase inhibitor C75 or non-steroidal anti-inflammatory drugs such as NS-398 and aspirin inhibited the LB biogenesis and also induced the down modulation of the eicosanoid production and the parasite replication. These findings show that LBs are organelles up modulated during the course of infection. Furthermore, the biogenesis of the LB is involved in the lipid mediator generation by both the macrophages and the parasite triggering escape mechanisms.
Collapse
Affiliation(s)
- Patrícia E de Almeida
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | | | - Gabriel S C Rodrigues
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| | - Heloisa D'Avila
- Laboratory of Cellular Biology, Department of Biology, Federal University of Juiz de Fora, Juiz de Fora, Brazil
| |
Collapse
|
24
|
Peña Cárcamo JR, Morell ML, Vázquez CA, Vatansever S, Upadhyay AS, Överby AK, Cordo SM, García CC. The interplay between viperin antiviral activity, lipid droplets and Junín mammarenavirus multiplication. Virology 2018; 514:216-229. [DOI: 10.1016/j.virol.2017.10.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 10/10/2017] [Accepted: 10/12/2017] [Indexed: 01/09/2023]
|
25
|
Tirinato L, Pagliari F, Limongi T, Marini M, Falqui A, Seco J, Candeloro P, Liberale C, Di Fabrizio E. An Overview of Lipid Droplets in Cancer and Cancer Stem Cells. Stem Cells Int 2017; 2017:1656053. [PMID: 28883835 PMCID: PMC5572636 DOI: 10.1155/2017/1656053] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Revised: 06/08/2017] [Accepted: 07/05/2017] [Indexed: 02/06/2023] Open
Abstract
For decades, lipid droplets have been considered as the main cellular organelles involved in the fat storage, because of their lipid composition. However, in recent years, some new and totally unexpected roles have been discovered for them: (i) they are active sites for synthesis and storage of inflammatory mediators, and (ii) they are key players in cancer cells and tissues, especially in cancer stem cells. In this review, we summarize the main concepts related to the lipid droplet structure and function and their involvement in inflammatory and cancer processes.
Collapse
Affiliation(s)
- L. Tirinato
- German Cancer Research Center (DKFZ), Heidelberg, Baden-Württemberg, Germany
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - F. Pagliari
- Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - T. Limongi
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Department of Applied Science and Technology (DISAT), Politecnico di Torino, Torino, Italy
| | - M. Marini
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - A. Falqui
- Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - J. Seco
- German Cancer Research Center (DKFZ), Heidelberg, Baden-Württemberg, Germany
| | - P. Candeloro
- BioNEM Lab, Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | - C. Liberale
- Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - E. Di Fabrizio
- Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| |
Collapse
|
26
|
Rasineni K, Donohue TM, Thomes PG, Yang L, Tuma DJ, McNiven MA, Casey CA. Ethanol-induced steatosis involves impairment of lipophagy, associated with reduced Dynamin2 activity. Hepatol Commun 2017; 1:501-512. [PMID: 29152606 PMCID: PMC5678901 DOI: 10.1002/hep4.1063] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 05/11/2017] [Accepted: 05/17/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Lipid droplets (LDs), the organelles central to alcoholic steatosis, are broken down by lipophagy, a specialized form of autophagy. Here, we hypothesize that ethanol administration retards lipophagy by down-regulating Dynamin 2 (Dyn2), a protein that facilitates lysosome re-formation, contributing to hepatocellular steatosis. METHODS Primary hepatocytes were isolated from male Wistar rats fed Lieber-DeCarli control or EtOH liquid diets for 6-8 wk. Hepatocytes were incubated in complete medium (fed) or nutrient-free medium (fasting) with or without the Dyn2 inhibitor Dynasore or the Src inhibitor SU6656. Phosphorylated (active) forms of Src and Dyn2, and markers of autophagy were quantified by Western Blot. Co-localization of LDs-with autophagic machinery was determined by confocal microscopy. RESULTS In hepatocytes from pair-fed rats, LD breakdown was accelerated during fasting, as judged by smaller LDs and lower TG content when compared to hepatocytes in complete media. Fasting-induced TG loss in control hepatocytes was significantly blocked by either SU6656 or Dynasore. Compared to controls, hepatocytes from EtOH-fed rats had 66% and 40% lower content of pSrc and pDyn2, respectively, coupled with lower rate of fasting-induced TG loss. This slower rate of fasting-induced TG loss was blocked in cells co-incubated with Dynasore. Microscopic examination of EtOH-fed rat hepatocytes revealed increased co-localization of the autophagosome marker LC3 on LDs with a concomitant decrease in lysosome marker LAMP1. Whole livers and LD fractions of EtOH-fed rats exhibited simultaneous increase in LC3II and p62 over that of controls, indicating a block in lipophagy. CONCLUSION Chronic ethanol administration slowed the rate of hepatocyte lipophagy, owing in part to lower levels of phosphorylated Src kinase available to activate its substrate, Dyn2, thereby causing depletion of lysosomes for LD breakdown.
Collapse
Affiliation(s)
- Karuna Rasineni
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Terrence M. Donohue
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNE
- Department of Pathology and MicrobiologyCollege of Medicine, University of Nebraska Medical CenterOmahaNE
- Center for Environmental ToxicologyCollege of Public Health, University of Nebraska Medical CenterOmahaNE
| | - Paul G. Thomes
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Li Yang
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Tongji HospitalTongji University School of MedicineShanghaiChina
| | - Dean J. Tuma
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
| | - Mark A. McNiven
- Department of Biochemistry and Molecular BiologyMayo Clinic College of MedicineRochesterMN
| | - Carol A. Casey
- The Liver Study UnitVA Nebraska‐Western Iowa Health Care System (VA NWIHCS)OmahaNE
- Department of Internal MedicineUniversity of Nebraska Medical CenterOmahaNE
- Department of Biochemistry and Molecular BiologyUniversity of Nebraska Medical CenterOmahaNE
| |
Collapse
|
27
|
Onal G, Kutlu O, Gozuacik D, Dokmeci Emre S. Lipid Droplets in Health and Disease. Lipids Health Dis 2017; 16:128. [PMID: 28662670 PMCID: PMC5492776 DOI: 10.1186/s12944-017-0521-7] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 06/16/2017] [Indexed: 12/16/2022] Open
Abstract
Lipids are essential building blocks synthesized by complex molecular pathways and deposited as lipid droplets (LDs) in cells. LDs are evolutionary conserved organelles found in almost all organisms, from bacteria to mammals. They are composed of a hydrophobic neutral lipid core surrounding by a phospholipid monolayer membrane with various decorating proteins. Degradation of LDs provide metabolic energy for divergent cellular processes such as membrane synthesis and molecular signaling. Lipolysis and autophagy are two main catabolic pathways of LDs, which regulate lipid metabolism and, thereby, closely engaged in many pathological conditons. In this review, we first provide an overview of the current knowledge on the structural properties and the biogenesis of LDs. We further focus on the recent findings of their catabolic mechanism by lipolysis and autophagy as well as their connection ragarding the regulation and function. Moreover, we discuss the relevance of LDs and their catabolism-dependent pathophysiological conditions.
Collapse
Affiliation(s)
- Gizem Onal
- Department of Medical Biology, Hacettepe University, 06100, Ankara, Turkey
| | - Ozlem Kutlu
- Nanotechnology Research and Application Center (SUNUM) & Center of Excellence for Functional Surfaces and Interfaces for Nano Diagnostics (EFSUN), Sabanci University, 34956, Istanbul, Turkey
| | - Devrim Gozuacik
- Molecular Biology, Genetics, and Bioengineering Program & Center of Excellence for Functional Surfaces and Interfaces for Nano Diagnostics (EFSUN), Sabanci University, 34956, Istanbul, Turkey
| | - Serap Dokmeci Emre
- Department of Medical Biology, Hacettepe University, 06100, Ankara, Turkey.
| |
Collapse
|
28
|
A snake venom group IIA PLA 2 with immunomodulatory activity induces formation of lipid droplets containing 15-d-PGJ 2 in macrophages. Sci Rep 2017. [PMID: 28642580 PMCID: PMC5481388 DOI: 10.1038/s41598-017-04498-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Crotoxin B (CB) is a catalytically active group IIA sPLA2 from Crotalus durissus terrificus snake venom. In contrast to most GIIA sPLA2s, CB exhibits anti-inflammatory effects, including the ability to inhibit leukocyte functions. Lipid droplets (LDs) are lipid-rich organelles associated with inflammation and recognized as a site for the synthesis of inflammatory lipid mediators. Here, the ability of CB to induce formation of LDs and the mechanisms involved in this effect were investigated in isolated macrophages. The profile of CB-induced 15-d-PGJ2 (15-Deoxy-Delta-12,14-prostaglandin J2) production and involvement of LDs in 15-d-PGJ2 biosynthesis were also investigated. Stimulation of murine macrophages with CB induced increased number of LDs and release of 15-d-PGJ2. LDs induced by CB were associated to PLIN2 recruitment and expression and required activation of PKC, PI3K, MEK1/2, JNK, iPLA2 and PLD. Both 15-d-PGJ2 and COX-1 were found in CB-induced LDs indicating that LDs contribute to the inhibitory effects of CB by acting as platform for synthesis of 15-d-PGJ2, a pro-resolving lipid mediator. Together, our data indicate that an immunomodulatory GIIA sPLA2 can directly induce LD formation and production of a pro-resolving mediator in an inflammatory cell and afford new insights into the roles of LDs in resolution of inflammatory processes.
Collapse
|
29
|
Khalifeh-Soltani A, Gupta D, Ha A, Iqbal J, Hussain M, Podolsky MJ, Atabai K. Mfge8 regulates enterocyte lipid storage by promoting enterocyte triglyceride hydrolase activity. JCI Insight 2016; 1:e87418. [PMID: 27812539 DOI: 10.1172/jci.insight.87418] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The small intestine has an underappreciated role as a lipid storage organ. Under conditions of high dietary fat intake, enterocytes can minimize the extent of postprandial lipemia by storing newly absorbed dietary fat in cytoplasmic lipid droplets. Lipid droplets can be subsequently mobilized for the production of chylomicrons. The mechanisms that regulate this process are poorly understood. We report here that the milk protein Mfge8 regulates hydrolysis of cytoplasmic lipid droplets in enterocytes after interacting with the αvβ3 and αvβ5 integrins. Mice deficient in Mfge8 or the αvβ3 and αvβ5 integrins accumulate excess cytoplasmic lipid droplets after a fat challenge. Mechanistically, interruption of the Mfge8-integrin axis leads to impaired enterocyte intracellular triglyceride hydrolase activity in vitro and in vivo. Furthermore, Mfge8 increases triglyceride hydrolase activity through a PI3 kinase/mTORC2-dependent signaling pathway. These data identify a key role for Mfge8 and the αvβ3 and αvβ5 integrins in regulating enterocyte lipid processing.
Collapse
Affiliation(s)
- Amin Khalifeh-Soltani
- Department of Medicine.,Cardiovascular Research Institute.,Lung Biology Center, University of California, San Francisco, San Francisco, California, USA
| | - Deepti Gupta
- Department of Medicine.,Cardiovascular Research Institute.,Lung Biology Center, University of California, San Francisco, San Francisco, California, USA
| | - Arnold Ha
- Department of Medicine.,Cardiovascular Research Institute
| | - Jahangir Iqbal
- Departments of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, New York, USA
| | - Mahmood Hussain
- Departments of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, New York, USA
| | - Michael J Podolsky
- Department of Medicine.,Cardiovascular Research Institute.,Lung Biology Center, University of California, San Francisco, San Francisco, California, USA
| | - Kamran Atabai
- Department of Medicine.,Cardiovascular Research Institute.,Lung Biology Center, University of California, San Francisco, San Francisco, California, USA
| |
Collapse
|
30
|
Li L, Zhang H, Wang W, Hong Y, Wang J, Zhang S, Xu S, Shu Q, Li J, Yang F, Zheng M, Qian Z, Liu P. Comparative proteomics reveals abnormal binding of ATGL and dysferlin on lipid droplets from pressure overload-induced dysfunctional rat hearts. Sci Rep 2016; 6:19782. [PMID: 26795240 PMCID: PMC4726412 DOI: 10.1038/srep19782] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 12/17/2015] [Indexed: 12/11/2022] Open
Abstract
Excessive retention of neutral lipids in cardiac lipid droplets (LDs) is a common observation in cardiomyopathy. Thus, the systematic investigation of the cardiac LD proteome will help to dissect the underlying mechanisms linking cardiac steatosis and myocardial dysfunction. Here, after isolation of LDs from normal and dysfunctional Sprague-Dawley rat hearts, we identified 752 heart-associated LD proteins using iTRAQ quantitative proteomic method, including 451 proteins previously unreported on LDs. The most noteworthy finding was the identification of the membrane resealing protein, dysferlin. An analysis of dysferlin truncation mutants indicated that its C2 domain was responsible for its LD localization. Quantitative proteomic results further determined that 27 proteins were increased and 16 proteins were decreased in LDs from post pressure overload-induced dysfunctional hearts, compared with normal hearts. Notably, adipose triacylglycerol lipase (ATGL) was dramatically decreased and dysferlin was substantially increased on dysfunctional cardiac LDs. This study for the first time reveals the dataset of the heart LD proteome in healthy tissue and the variation of it under cardiac dysfunction. These findings highlight an association between the altered LD protein localization of dysferlin and ATGL and myocardial dysfunction.
Collapse
Affiliation(s)
- Linghai Li
- Department of Anesthesiology, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China.,National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Huina Zhang
- Beijing An Zhen Hospital, Capital Medical University, Key Laboratory of Upper Airway Dysfunction-related Cardiovascular Diseases, Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing, China.,National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Weiyi Wang
- Department of Cardiovascular Diseases, Civil Aviation General Hospital, Peking University, Beijing, China
| | - Yun Hong
- Department of Gastroenterology, the First Affiliated Hospital, College of Medicine, Zhejang University, Hangzhou, China
| | - Jifeng Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Shuyan Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Shimeng Xu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Qingbo Shu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Juanfen Li
- Department of Cardiology, Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Fuquan Yang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Min Zheng
- Department of Gastroenterology, the First Affiliated Hospital, College of Medicine, Zhejang University, Hangzhou, China
| | - Zongjie Qian
- Department of Cardiology, Affiliated Hospital of Guilin Medical University, Guilin, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| |
Collapse
|
31
|
Urrutia RA, Kalinec F. Biology and pathobiology of lipid droplets and their potential role in the protection of the organ of Corti. Hear Res 2015; 330:26-38. [PMID: 25987503 PMCID: PMC5391798 DOI: 10.1016/j.heares.2015.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 04/17/2015] [Accepted: 04/21/2015] [Indexed: 12/20/2022]
Abstract
The current review article seeks to extend our understanding on the role of lipid droplets within the organ of Corti. In addition to presenting an overview of the current information about the origin, structure and function of lipid droplets we draw inferences from the collective body of knowledge about this cellular organelle to build a conceptual framework to better understanding their role in auditory function. This conceptual model considers that lipid droplets play a significant role in the synthesis, storage, and release of lipids and proteins for energetic use and/or modulating cell signaling pathways. We describe the role and mechanism by which LD play a role in human diseases, and we also review emerging data from our laboratory revealing the potential role of lipid droplets from Hensen cells in the auditory organ. We suggest that lipid droplets might help to develop rapidly and efficiently the resolution phase of inflammatory responses in the mammalian cochlea, preventing inflammatory damage of the delicate inner ear structures and, consequently, sensorineural hearing loss.
Collapse
Affiliation(s)
- Raul A Urrutia
- Epigenetics and Chromatin Dynamics Laboratory, Translational Epigenomic Program, Center for Individualized Medicine (CIM) Mayo Clinic, Rochester, MN 55905, USA
| | - Federico Kalinec
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
| |
Collapse
|
32
|
Melo RCN, Weller PF. Lipid droplets in leukocytes: Organelles linked to inflammatory responses. Exp Cell Res 2015; 340:193-7. [PMID: 26515551 DOI: 10.1016/j.yexcr.2015.10.028] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/23/2015] [Indexed: 01/21/2023]
Abstract
Studies on lipid droplets (LDs) in leukocytes have attracted attention due to their association with human diseases. In these cells, LDs are rapidly formed in response to inflammatory stimuli or allergic/inflammatory diseases including infections with parasites and bacteria. Leukocyte LDs are linked to the regulation of immune responses by compartmentalization of several proteins and lipids involved in the control and biosynthesis of inflammatory mediators (eicosanoids). In this mini review, we summarize current knowledge on the composition, structure and function of leukocyte LDs, organelles now considered as structural markers of inflammation.
Collapse
Affiliation(s)
- Rossana C N Melo
- Laboratory of Cellular Biology, Department of Biology, ICB, Federal University of Juiz de Fora, UFJF, Rua José Lourenço Kelmer, Juiz de Fora, MG 36036-900, Brazil; Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 943, Boston, MA 02215, USA.
| | - Peter F Weller
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, CLS 943, Boston, MA 02215, USA.
| |
Collapse
|
33
|
Tirinato L, Liberale C, Di Franco S, Candeloro P, Benfante A, La Rocca R, Potze L, Marotta R, Ruffilli R, Rajamanickam VP, Malerba M, De Angelis F, Falqui A, Carbone E, Todaro M, Medema JP, Stassi G, Di Fabrizio E. Lipid droplets: a new player in colorectal cancer stem cells unveiled by spectroscopic imaging. Stem Cells 2015; 33:35-44. [PMID: 25186497 PMCID: PMC4311668 DOI: 10.1002/stem.1837] [Citation(s) in RCA: 172] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 08/12/2014] [Indexed: 12/14/2022]
Abstract
The cancer stem cell (CSC) model is describing tumors as a hierarchical organized system and CSCs are suggested to be responsible for cancer recurrence after therapy. The identification of specific markers of CSCs is therefore of paramount importance. Here, we show that high levels of lipid droplets (LDs) are a distinctive mark of CSCs in colorectal (CR) cancer. This increased lipid content was clearly revealed by label-free Raman spectroscopy and it directly correlates with well-accepted CR-CSC markers as CD133 and Wnt pathway activity. By xenotransplantation experiments, we have finally demonstrated that CR-CSCs overexpressing LDs retain most tumorigenic potential. A relevant conceptual advance in this work is the demonstration that a cellular organelle, the LD, is a signature of CSCs, in addition to molecular markers. A further functional characterization of LDs could lead soon to design new target therapies against CR-CSCs. Stem Cells2015;33:35–44
Collapse
Affiliation(s)
- Luca Tirinato
- PSE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia; BioNEM Lab, Department of Experimental and Clinical Medicine, University Magna Graecia of Catanzaro, Catanzaro, Italy
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Fazolini NPB, Cruz ALS, Werneck MBF, Viola JPB, Maya-Monteiro CM, Bozza PT. Leptin activation of mTOR pathway in intestinal epithelial cell triggers lipid droplet formation, cytokine production and increased cell proliferation. Cell Cycle 2015; 14:2667-76. [PMID: 26017929 PMCID: PMC4614828 DOI: 10.1080/15384101.2015.1041684] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Accumulating evidence suggests that obesity and enhanced inflammatory reactions are predisposing conditions for developing colon cancer. Obesity is associated with high levels of circulating leptin. Leptin is an adipocytokine that is secreted by adipose tissue and modulates immune response and inflammation. Lipid droplets (LD) are organelles involved in lipid metabolism and production of inflammatory mediators, and increased numbers of LD were observed in human colon cancer. Leptin induces the formation of LD in macrophages in a PI3K/mTOR pathway-dependent manner. Moreover, the mTOR is a serine/threonine kinase that plays a key role in cellular growth and is frequently altered in tumors. We therefore investigated the role of leptin in the modulation of mTOR pathway and regulation of lipid metabolism and inflammatory phenotype in intestinal epithelial cells (IEC-6 cells). We show that leptin promotes a dose- and time-dependent enhancement of LD formation. The biogenesis of LD was accompanied by enhanced CXCL1/CINC-1, CCL2/MCP-1 and TGF-β production and increased COX-2 expression in these cells. We demonstrated that leptin-induced increased phosphorylation of STAT3 and AKT and a dose and time-dependent mTORC activation with enhanced phosphorilation of the downstream protein P70S6K protein. Pre-treatment with rapamycin significantly inhibited leptin effects in LD formation, COX-2 and TGF-β production in IEC-6 cells. Moreover, leptin was able to stimulate the proliferation of epithelial cells on a mTOR-dependent manner. We conclude that leptin regulates lipid metabolism, cytokine production and proliferation of intestinal cells through a mechanism largely dependent on activation of the mTOR pathway, thus suggesting that leptin-induced mTOR activation may contribute to the obesity-related enhanced susceptibility to colon carcinoma.
Collapse
Affiliation(s)
- Narayana P B Fazolini
- a Laboratory of Immunopharmacology; Oswaldo Cruz Institute; FIOCRUZ ; Rio de Janeiro , Brazil
| | | | | | | | | | | |
Collapse
|
35
|
Bouchez I, Pouteaux M, Canonge M, Genet M, Chardot T, Guillot A, Froissard M. Regulation of lipid droplet dynamics in Saccharomyces cerevisiae depends on the Rab7-like Ypt7p, HOPS complex and V1-ATPase. Biol Open 2015; 4:764-75. [PMID: 25948753 PMCID: PMC4571102 DOI: 10.1242/bio.20148615] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
It has now been clearly shown that lipid droplets (LDs) play a dynamic role in the cell. This was reinforced by LD proteomics which suggest that a significant number of trafficking proteins are associated with this organelle. Using microscopy, we showed that LDs partly co-localize with the vacuole in S. cerevisiae. Immunoblot experiments confirmed the association of the vacuolar Rab GTPase Rab7-like Ypt7p with LDs. We observed an increase in fatty acid content and LD number in ypt7Δ mutant and also changes in LD morphology and intra LD fusions, revealing a direct role for Ypt7p in LD dynamics. Using co-immunoprecipitation, we isolated potential Ypt7p partners including, Vma13p, the H subunit of the V1 part of the vacuolar (H+) ATPase (V-ATPase). Deletion of the VMA13 gene, as well as deletion of three other subunits of the V1 part of the V-ATPase, also increased the cell fatty acid content and LD number. Mutants of the Homotypic fusion and vacuole protein sorting (HOPS) complex showed similar phenotypes. Here, we demonstrated that LD dynamics and membrane trafficking between the vacuole and LDs are regulated by the Rab7-like Ypt7p and are impaired when the HOPS complex and the V1 domain of the V-ATPase are defective.
Collapse
Affiliation(s)
- Isabelle Bouchez
- Institut Jean-Pierre Bourgin IJPB, UMR 1318 INRA, Saclay Plant Sciences, route de St Cyr (RD 10), 78026, Versailles cedex, France Institut Jean-Pierre Bourgin IJPB, UMR 1318 AgroParisTech, route de St Cyr (RD 10), 78026, Versailles cedex, France
| | - Marie Pouteaux
- Institut Jean-Pierre Bourgin IJPB, UMR 1318 INRA, Saclay Plant Sciences, route de St Cyr (RD 10), 78026, Versailles cedex, France Institut Jean-Pierre Bourgin IJPB, UMR 1318 AgroParisTech, route de St Cyr (RD 10), 78026, Versailles cedex, France
| | - Michel Canonge
- Institut Jean-Pierre Bourgin IJPB, UMR 1318 INRA, Saclay Plant Sciences, route de St Cyr (RD 10), 78026, Versailles cedex, France Institut Jean-Pierre Bourgin IJPB, UMR 1318 AgroParisTech, route de St Cyr (RD 10), 78026, Versailles cedex, France
| | - Mélanie Genet
- Institut Jean-Pierre Bourgin IJPB, UMR 1318 INRA, Saclay Plant Sciences, route de St Cyr (RD 10), 78026, Versailles cedex, France Institut Jean-Pierre Bourgin IJPB, UMR 1318 AgroParisTech, route de St Cyr (RD 10), 78026, Versailles cedex, France
| | - Thierry Chardot
- Institut Jean-Pierre Bourgin IJPB, UMR 1318 INRA, Saclay Plant Sciences, route de St Cyr (RD 10), 78026, Versailles cedex, France Institut Jean-Pierre Bourgin IJPB, UMR 1318 AgroParisTech, route de St Cyr (RD 10), 78026, Versailles cedex, France
| | - Alain Guillot
- MICALIS PAPPSO, UMR 1319 INRA, Domaine de Vilvert 78352, Jouy-en-Josas cedex, France MICALIS PAPPSO, UMR 1319 AgroParisTech, Domaine de Vilvert 78352, Jouy-en-Josas cedex, France
| | - Marine Froissard
- Institut Jean-Pierre Bourgin IJPB, UMR 1318 INRA, Saclay Plant Sciences, route de St Cyr (RD 10), 78026, Versailles cedex, France Institut Jean-Pierre Bourgin IJPB, UMR 1318 AgroParisTech, route de St Cyr (RD 10), 78026, Versailles cedex, France
| |
Collapse
|
36
|
Zoccal KF, Paula-Silva FWG, Bitencourt CDS, Sorgi CA, Bordon KDCF, Arantes EC, Faccioli LH. PPAR-γ activation by Tityus serrulatus venom regulates lipid body formation and lipid mediator production. Toxicon 2014; 93:90-7. [PMID: 25450800 DOI: 10.1016/j.toxicon.2014.11.226] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/31/2014] [Accepted: 11/13/2014] [Indexed: 02/06/2023]
Abstract
Tityus serrulatus venom (TsV) consists of numerous peptides with different physiological and pharmacological activities. Studies have shown that scorpion venom increases pro-inflammatory cytokine production, contributing to immunological imbalance, multiple organ dysfunction, and patient death. We have previously demonstrated that TsV is a venom-associated molecular pattern (VAMP) recognized by TLRs inducing intense inflammatory reaction through the production of pro-inflammatory cytokines and arachidonic acid-derived lipid mediators prostaglandin (PG)E2 and leukotriene (LT)B4. Lipid bodies (LBs) are potential sites for eicosanoid production by inflammatory cells. Moreover, recent studies have shown that the peroxisome proliferator-activated receptor gamma (PPAR-γ) is implicated in LB formation and acts as an important modulator of lipid metabolism during inflammation. In this study, we used murine macrophages to evaluate whether the LB formation induced by TsV after TLR recognition correlates with lipid mediator generation by macrophages and if it occurs through PPAR-γ activation. We demonstrate that TsV acts through TLR2 and TLR4 stimulation and PPAR-γ activation to induce LB formation and generation of PGE2 and LTB4. Our data also show that PPAR-γ negatively regulates the pro-inflammatory NF-κB transcription factor. Based on these results, we suggest that during envenomation, LBs constitute functional organelles for lipid mediator production through signaling pathways that depend on cell surface and nuclear receptors. These findings point to the inflammatory mechanisms that might also be triggered during human envenomation by TsV.
Collapse
Affiliation(s)
- Karina Furlani Zoccal
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil.
| | - Francisco Wanderley Garcia Paula-Silva
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil.
| | - Claudia da Silva Bitencourt
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil.
| | - Carlos Artério Sorgi
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil.
| | | | - Eliane Candiani Arantes
- Departamento de Física e Química, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil.
| | - Lúcia Helena Faccioli
- Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Brazil.
| |
Collapse
|
37
|
McMahon D, Dinh A, Kurz D, Shah D, Han GS, Carman GM, Brasaemle DL. Comparative gene identification 58/α/β hydrolase domain 5 lacks lysophosphatidic acid acyltransferase activity. J Lipid Res 2014; 55:1750-61. [PMID: 24879803 DOI: 10.1194/jlr.m051151] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Indexed: 01/07/2023] Open
Abstract
Mutations in the gene encoding comparative gene identification 58 (CGI-58)/α/β hydrolase domain 5 (ABHD5) cause Chanarin-Dorfman syndrome, characterized by excessive triacylglycerol storage in cells and tissues. CGI-58 has been identified as a coactivator of adipose TG lipase (ATGL) and a lysophosphatidic acid acyltransferase (LPAAT). We developed a molecular model of CGI-58 structure and then mutated predicted active site residues and performed LPAAT activity assays of recombinant WT and mutated CGI-58. When mutations of predicted catalytic residues failed to reduce LPAAT activity, we determined that LPAAT activity was due to a bacterial contaminant of affinity purification procedures, plsC, the sole LPAAT in Escherichia coli Purification protocols were optimized to reduce plsC contamination, in turn reducing LPAAT activity. When CGI-58 was expressed in SM2-1(DE3) cells that lack plsC, lysates lacked LPAAT activity. Additionally, mouse CGI-58 expressed in bacteria as a glutathione-S-transferase fusion protein and human CGI-58 expressed in yeast lacked LPAAT activity. Previously reported lipid binding activity of CGI-58 was revisited using protein-lipid overlays. Recombinant CGI-58 failed to bind lysophosphatidic acid, but interestingly, bound phosphatidylinositol 3-phosphate [PI(3)P] and phosphatidylinositol 5-phosphate [PI(5)P]. Prebinding CGI-58 with PI(3)P or PI(5)P did not alter its coactivation of ATGL in vitro. In summary, purified recombinant CGI-58 that is functional as an ATGL coactivator lacks LPAAT activity.
Collapse
Affiliation(s)
- Derek McMahon
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| | - Anna Dinh
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| | - Daniel Kurz
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| | - Dharika Shah
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| | - Gil-Soo Han
- Rutgers, The State University of New Jersey, New Brunswick, NJ 08901
| | - George M Carman
- Rutgers, The State University of New Jersey, New Brunswick, NJ 08901
| | - Dawn L Brasaemle
- Rutgers Center for Lipid Research and Department of Nutritional Sciences and Rutgers Center for Lipid Research and Department of Food Science
| |
Collapse
|
38
|
Pfisterer SG, Bakula D, Frickey T, Cezanne A, Brigger D, Tschan MP, Robenek H, Proikas-Cezanne T. Lipid droplet and early autophagosomal membrane targeting of Atg2A and Atg14L in human tumor cells. J Lipid Res 2014; 55:1267-78. [PMID: 24776541 DOI: 10.1194/jlr.m046359] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Indexed: 12/26/2022] Open
Abstract
Autophagy is a lysosomal bulk degradation pathway for cytoplasmic cargo, such as long-lived proteins, lipids, and organelles. Induced upon nutrient starvation, autophagic degradation is accomplished by the concerted actions of autophagy-related (ATG) proteins. Here we demonstrate that two ATGs, human Atg2A and Atg14L, colocalize at cytoplasmic lipid droplets (LDs) and are functionally involved in controlling the number and size of LDs in human tumor cell lines. We show that Atg2A is targeted to cytoplasmic ADRP-positive LDs that migrate bidirectionally along microtubules. The LD localization of Atg2A was found to be independent of the autophagic status. Further, Atg2A colocalized with Atg14L under nutrient-rich conditions when autophagy was not induced. Upon nutrient starvation and dependent on phosphatidylinositol 3-phosphate [PtdIns(3)P] generation, both Atg2A and Atg14L were also specifically targeted to endoplasmic reticulum-associated early autophagosomal membranes, marked by the PtdIns(3)P effectors double-FYVE containing protein 1 (DFCP1) and WD-repeat protein interacting with phosphoinositides 1 (WIPI-1), both of which function at the onset of autophagy. These data provide evidence for additional roles of Atg2A and Atg14L in the formation of early autophagosomal membranes and also in lipid metabolism.
Collapse
Affiliation(s)
- Simon G Pfisterer
- Autophagy Laboratory, Department of Molecular Biology, Interfaculty Institute for Cell Biology, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Daniela Bakula
- Autophagy Laboratory, Department of Molecular Biology, Interfaculty Institute for Cell Biology, Eberhard Karls University Tuebingen, Tuebingen, Germany International Max Planck Research School 'From Molecules to Organisms', Max Planck Institute for Developmental Biology and Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Tancred Frickey
- Applied Bioinformatics Laboratory, University of Konstanz, Konstanz, Germany
| | - Alice Cezanne
- Autophagy Laboratory, Department of Molecular Biology, Interfaculty Institute for Cell Biology, Eberhard Karls University Tuebingen, Tuebingen, Germany
| | - Daniel Brigger
- Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland
| | - Mario P Tschan
- Division of Experimental Pathology, Institute of Pathology, University of Bern, Bern, Switzerland
| | - Horst Robenek
- Leibniz Institute for Arteriosklerosis Research, University of Muenster, Muenster, Germany
| | - Tassula Proikas-Cezanne
- Autophagy Laboratory, Department of Molecular Biology, Interfaculty Institute for Cell Biology, Eberhard Karls University Tuebingen, Tuebingen, Germany International Max Planck Research School 'From Molecules to Organisms', Max Planck Institute for Developmental Biology and Eberhard Karls University Tuebingen, Tuebingen, Germany
| |
Collapse
|
39
|
Aymé L, Baud S, Dubreucq B, Joffre F, Chardot T. Function and localization of the Arabidopsis thaliana diacylglycerol acyltransferase DGAT2 expressed in yeast. PLoS One 2014; 9:e92237. [PMID: 24663078 PMCID: PMC3963872 DOI: 10.1371/journal.pone.0092237] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/19/2014] [Indexed: 11/22/2022] Open
Abstract
Diacylglycerol acyltransferases (DGATs) catalyze the final and only committed step of triacylglycerol synthesis. DGAT activity is rate limiting for triacylglycerol accumulation in mammals, plants and microbes. DGATs belong to three different evolutionary classes. In Arabidopsis thaliana, DGAT1, encoded by At2g19450, is the major DGAT enzyme involved in triacylglycerol accumulation in seeds. Until recently, the function of DGAT2 (At3g51520) has remained elusive. Previous attempts to characterize its enzymatic function by heterologous expression in yeast were unsuccessful. In the present report we demonstrate that expression of a codon-optimized version of the DGAT2 gene is able to restore neutral lipid accumulation in the Saccharomyces cerevisiae mutant strain (H1246), which is defective in triacylglycerol biosynthesis. Heterologous expression of codon-optimized DGAT2 and DGAT1 induced the biogenesis of subcellular lipid droplets containing triacylglycerols and squalene. Both DGAT proteins were found to be associated with these lipid droplets. The fatty acid composition was affected by the nature of the acyltransferase expressed. DGAT2 preferentially incorporated C16:1 fatty acids whereas DGAT1 displayed preference for C16:0, strongly suggesting that these enzymes have contrasting substrate specificities.
Collapse
Affiliation(s)
- Laure Aymé
- INRA, UMR1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France
| | - Sébastien Baud
- INRA, UMR1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France
| | - Bertrand Dubreucq
- INRA, UMR1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France
| | | | - Thierry Chardot
- INRA, UMR1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Versailles, France
- * E-mail:
| |
Collapse
|
40
|
Tan JSY, Seow CJP, Goh VJ, Silver DL. Recent advances in understanding proteins involved in lipid droplet formation, growth and fusion. J Genet Genomics 2014; 41:251-9. [PMID: 24894352 DOI: 10.1016/j.jgg.2014.03.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 03/03/2014] [Accepted: 03/05/2014] [Indexed: 01/29/2023]
Abstract
Lipid droplets (LDs) were once viewed as simple, inert lipid micelles. However, they are now known to be organelles with a rich proteome involved in a myriad of cellular processes. LDs are heterogeneous in nature with different sizes and compositions of phospholipids, neutral lipids and proteins. This review takes a focused look at the roles of proteins involved in the regulation of LD formation, expansion, and morphology. The related proteins are summarized such as the fat-specific protein (Fsp27), fat storage-inducing transmembrane (FIT) proteins, seipin and ADP-ribosylation factor 1-coat protein complex I (Arf-COPI). Finally, we present important challenges in LD biology for a deeper understanding of this dynamic organelle to be achieved.
Collapse
Affiliation(s)
- Jolene S Y Tan
- Signature Research Program in Cardiovascular & Metabolic Disorders, Duke-NUS Graduate Medical School Singapore, Singapore 169857, Singapore
| | - Colin J P Seow
- Signature Research Program in Cardiovascular & Metabolic Disorders, Duke-NUS Graduate Medical School Singapore, Singapore 169857, Singapore
| | - Vera J Goh
- Signature Research Program in Cardiovascular & Metabolic Disorders, Duke-NUS Graduate Medical School Singapore, Singapore 169857, Singapore
| | - David L Silver
- Signature Research Program in Cardiovascular & Metabolic Disorders, Duke-NUS Graduate Medical School Singapore, Singapore 169857, Singapore.
| |
Collapse
|
41
|
Rasineni K, McVicker BL, Tuma DJ, McNiven MA, Casey CA. Rab GTPases associate with isolated lipid droplets (LDs) and show altered content after ethanol administration: potential role in alcohol-impaired LD metabolism. Alcohol Clin Exp Res 2013; 38:327-35. [PMID: 24117505 DOI: 10.1111/acer.12271] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Accepted: 08/06/2013] [Indexed: 01/22/2023]
Abstract
BACKGROUND Alcoholic liver disease is manifested by the presence of fatty liver, primarily due to accumulation of hepatocellular lipid droplets (LDs). The presence of membrane-trafficking proteins (e.g., Rab GTPases) with LDs indicates that LDs may be involved in trafficking pathways known to be altered in ethanol (EtOH) damaged hepatocytes. As these Rab GTPases are crucial regulators of protein trafficking, we examined the effect EtOH administration has on hepatic Rab protein content and association with LDs. METHODS Male Wistar rats were pair-fed Lieber-DeCarli diets for 5 to 8 weeks. Whole liver and isolated LD fractions were analyzed. Identification of LDs and associated Rab proteins was performed in frozen liver or paraffin-embedded sections followed by immunohistochemical analysis. RESULTS Lipid accumulation was characterized by larger LD vacuoles and increased total triglyceride content in EtOH-fed rats. Rabs 1, 2, 3d, 5, 7, and 18 were analyzed in postnuclear supernatant (PNS) as well as LDs. All of the Rabs were found in the PNS, and Rabs 1, 2, 5, and 7 did not show alcohol-altered content, while Rab 3d content was reduced by over 80%, and Rab 18 also showed EtOH-induced reduction in content. Rab 3d was not found to associate with LDs, while all other Rabs were found in the LD fractions, and several showed an EtOH-related decrease (Rabs 2, 5, 7, 18). Immunohistochemical analysis revealed the enhanced content of a LD-associated protein, perilipin 2 (PLIN2) that was paralleled with an associated decrease of Rab 18 in EtOH-fed rat sections. CONCLUSIONS Chronic EtOH feeding was associated with increased PLIN2 and altered Rab GTPase content in enriched LD fractions. Although mechanisms driving these changes are not established, further studies on intracellular protein trafficking and LD biology after alcohol administration will likely contribute to our understanding of fatty liver disease.
Collapse
Affiliation(s)
- Karuna Rasineni
- The Liver Study Unit, VA Nebraska-Western Iowa Health Care System (VA NWIHCS), Omaha, Nebraska; Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska
| | | | | | | | | |
Collapse
|
42
|
Single cell synchrotron FT-IR microspectroscopy reveals a link between neutral lipid and storage carbohydrate fluxes in S. cerevisiae. PLoS One 2013; 8:e74421. [PMID: 24040242 PMCID: PMC3770668 DOI: 10.1371/journal.pone.0074421] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Accepted: 08/01/2013] [Indexed: 12/14/2022] Open
Abstract
In most organisms, storage lipids are packaged into specialized structures called lipid droplets. These contain a core of neutral lipids surrounded by a monolayer of phospholipids, and various proteins which vary depending on the species. Hydrophobic structural proteins stabilize the interface between the lipid core and aqueous cellular environment (perilipin family of proteins, apolipoproteins, oleosins). We developed a genetic approach using heterologous expression in Saccharomyces cerevisiae of the Arabidopsis thaliana lipid droplet oleosin and caleosin proteins AtOle1 and AtClo1. These transformed yeasts overaccumulate lipid droplets, leading to a specific increase in storage lipids. The phenotype of these cells was explored using synchrotron FT-IR microspectroscopy to investigate the dynamics of lipid storage and cellular carbon fluxes reflected as changes in spectral fingerprints. Multivariate statistical analysis of the data showed a clear effect on storage carbohydrates and more specifically, a decrease in glycogen in our modified strains. These observations were confirmed by biochemical quantification of the storage carbohydrates glycogen and trehalose. Our results demonstrate that neutral lipid and storage carbohydrate fluxes are tightly connected and co-regulated.
Collapse
|
43
|
Vindigni JD, Wien F, Giuliani A, Erpapazoglou Z, Tache R, Jagic F, Chardot T, Gohon Y, Froissard M. Fold of an oleosin targeted to cellular oil bodies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1881-8. [DOI: 10.1016/j.bbamem.2013.04.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Revised: 03/26/2013] [Accepted: 04/09/2013] [Indexed: 01/18/2023]
|
44
|
Falanga YT, Chaimowitz NS, Charles N, Finkelman FD, Pullen NA, Barbour S, Dholaria K, Faber T, Kolawole M, Huang B, Odom S, Rivera J, Carlyon J, Conrad DH, Spiegel S, Oskeritzian CA, Ryan JJ. Lyn but not Fyn kinase controls IgG-mediated systemic anaphylaxis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2012; 188:4360-8. [PMID: 22450804 PMCID: PMC3536057 DOI: 10.4049/jimmunol.1003223] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Anaphylaxis is a rapid, life-threatening hypersensitivity reaction. Until recently, it was mainly attributed to histamine released by mast cells activated by allergen crosslinking (XL) of FcεRI-bound allergen-specific IgE. However, recent reports established that anaphylaxis could also be triggered by basophil, macrophage, and neutrophil secretion of platelet-activating factor subsequent to FcγR stimulation by IgG/Ag complexes. We have investigated the contribution of Fyn and Lyn tyrosine kinases to FcγRIIb and FcγRIII signaling in the context of IgG-mediated passive systemic anaphylaxis (PSA). We found that mast cell IgG XL induced Fyn, Lyn, Akt, Erk, p38, and JNK phosphorylation. Additionally, IgG XL of mast cells, basophils, and macrophages resulted in Fyn- and Lyn-regulated mediator release in vitro. FcγR-mediated activation was enhanced in Lyn-deficient (knockout [KO]) cells, but decreased in Fyn KO cells, compared with wild-type cells. More importantly, Lyn KO mice displayed significantly exacerbated PSA features whereas no change was observed for Fyn KO mice, compared with wild-type littermates. Intriguingly, we establish that mast cells account for most serum histamine in IgG-induced PSA. Taken together, our findings establish pivotal roles for Fyn and Lyn in the regulation of PSA and highlight their unsuspected functions in IgG-mediated pathologies.
Collapse
Affiliation(s)
- Yves T. Falanga
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
| | - Natalia S. Chaimowitz
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298 USA
| | - Nicolas Charles
- Inserm U699 "Immunopathologie Rénale, Récepteurs et Inflammation", Faculté de Médecine Xavier Bichat - Université Paris VII Denis Diderot, 75870 PARIS cedex 18, France
| | - Fred D. Finkelman
- Research Service, Cincinnati Veterans Affairs Medical Center, Cincinnati, OH 45220, § Division of Immunology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, § Division of Immunobiology, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Nicholas A. Pullen
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
| | - Suzanne Barbour
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298 USA
| | - Kevin Dholaria
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
| | - Travis Faber
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
| | - Motunrayo Kolawole
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
| | - Bernice Huang
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298 USA
| | - Sandra Odom
- Laboratory of Molecular Immunogenetics, NIAMS, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Juan Rivera
- Laboratory of Molecular Immunogenetics, NIAMS, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jason Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298 USA
| | - Daniel H. Conrad
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298 USA
| | - Sarah Spiegel
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
| | - Carole A. Oskeritzian
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University School of Medicine, Richmond, VA 23298
| | - John J. Ryan
- Department of Biology, Virginia Commonwealth University, Richmond, VA 23284
| |
Collapse
|
45
|
Pan X, Wilson M, McConville C, Brundler MA, Arvanitis TN, Shockcor JP, Griffin JL, Kauppinen RA, Peet AC. The lipid composition of isolated cytoplasmic lipid droplets from a human cancer cell line, BE(2)M17. MOLECULAR BIOSYSTEMS 2012; 8:1694-700. [PMID: 22517214 DOI: 10.1039/c2mb05485j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
(1)H nuclear magnetic resonance spectroscopy (NMR) resonances from lipids in tumours are associated with tumour grade and treatment response. The origin of these NMR signals is mainly considered to be cytoplasmic lipid droplets (LDs). Techniques exist for isolating LDs but little is known about their composition and its relationship to NMR signals. In this work, density-gradient ultracentrifugation was performed on homogenised human cancer cells to isolate LDs. (1)H NMR was performed on whole cells, isolated LDs and their extracts. Heteronuclear single quantum coherence spectroscopy (HSQC) and liquid chromatography mass spectroscopy (LC-MS) were performed on lipid extracts of LDs. Staining and microscopy were used to characterize isolated LDs. An excellent agreement in chemical shift and relative signal intensity was observed between lipid resonances in cells and isolated LD spectra supporting that NMR-visible lipids originate primarily from LDs. Isolated LDs showed high concentrations of unsaturated lipids, a oleic-to-linoleic acid ratio greater than two and a cholesteryl ester (ChE)-to-cholesterol (Ch) ratio close to unity. These ratios were several-fold greater than respective ratios in whole cells, demonstrating isolation is important to characterize LD composition. LDs contain a specific group of lipid species that are likely to contribute to the (1)H NMR spectrum of cells.
Collapse
Affiliation(s)
- Xiaoyan Pan
- Cancer Sciences, Institute of Child Health, University of Birmingham, Birmingham, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
46
|
The proteome of cytosolic lipid droplets isolated from differentiated Caco-2/TC7 enterocytes reveals cell-specific characteristics. Biol Cell 2012; 103:499-517. [PMID: 21787361 PMCID: PMC3181828 DOI: 10.1042/bc20110024] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Background information. Intestinal absorption of alimentary lipids is a complex process ensured by enterocytes and leading to TRL [TAG (triacylglycerol)-rich lipoprotein] assembly and secretion. The accumulation of circulating intestine-derived TRL is associated with atherosclerosis, stressing the importance of the control of postprandial hypertriglyceridaemia. During the postprandial period, TAGs are also transiently stored as CLDs (cytosolic lipid droplets) in enterocytes. As a first step for determining whether CLDs could play a role in the control of enterocyte TRL secretion, we analysed the protein endowment of CLDs isolated by sucrose-gradient centrifugation from differentiated Caco-2/TC7 enterocytes, the only human model able to secrete TRL in culture and to store transiently TAGs as CLDs when supplied with lipids. Cells were analysed after a 24 h incubation with lipid micelles and thus in a state of CLD-associated TAG mobilization. Results. Among the 105 proteins identified in the CLD fraction by LC-MS/MS (liquid chromatography coupled with tandem MS), 27 were directly involved in lipid metabolism pathways potentially relevant to enterocyte-specific functions. The transient feature of CLDs was consistent with the presence of proteins necessary for fatty acid activation (acyl-CoA synthetases) and for TAG hydrolysis. In differentiated Caco-2/TC7 enterocytes, we identified for the first time LPCAT2 (lysophosphatidylcholine acyltransferase 2), involved in PC (phosphatidylcholine) synthesis, and 3BHS1 (3-β-hydroxysteroid dehydrogenase 1), involved in steroid metabolism, and confirmed their partial CLD localization by immunofluorescence. In enterocytes, LPCAT2 may provide an economical source of PC, necessary for membrane synthesis and lipoprotein assembly, from the lysoPC present in the intestinal lumen. We also identified proteins involved in lipoprotein metabolism, such as ApoA-IV (apolipoprotein A-IV), which is specifically expressed by enterocytes and has been proposed to play many functions in vivo, including the formation of lipoproteins and the control of their size. The association of ApoA-IV with CLD was confirmed by confocal and immunoelectron microscopy and validated in vivo in the jejunum of mice fed with a high-fat diet. Conclusions. We report for the first time the protein endowment of Caco-2/TC7 enterocyte CLDs. Our results suggest that their formation and mobilization may participate in the control of enterocyte TRL secretion in a cell-specific manner.
Collapse
|
47
|
Sybirna NO, Brodiak IV, Bars'ka ML, Vovk OI. [Participation of phosphatidylinositol-3'-kinase in signal transduction through galactosyl-containing glycoprotein receptors of segmentonuclear leukocytes under type 1 diabetes mellitus]. ACTA ACUST UNITED AC 2012; 58:9-22. [PMID: 23530409 DOI: 10.15407/fz58.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
It is shown that reduction of beta,D-galactosyl-containing carbohydrate determinants ofglycoconjugates on theplasmatic membrane of segmentonuclear neutrophills of peripheral blood under type 1 diabetes mellitus (DM) is correlated with changes in aggregation of these cells and may cause their functional disorder. Changes in the parameters of ricin-induced neutrophil activation after inhibition of the phosphatidylinositol-3'-kinase (PI-3'-kinase) enzyme with wortmannin indicated that the functional state ofpolymorphonuclear leukocytes is mediated by signaling pathways in which PI-3'-kinase is involved. Thus, PI-3'-kinase-dependent signal networks are involved in the processes of signal transduction through galactosyl-containing glycoprotein receptors into neutrophilic leukocytes. Inertness of the intensity formation in time ofneutrophil granulocyte cell response on RCA-induced translocation of the p85alpha regulatory subunit of PI-3'-kinase from the cytosolic to the membrane fraction under type 1 DM is a consequence of changes in the number or structure of plasmatic galactosyl-containing glycoprotein receptors. The revealed changes may be etiologic premise of diabetic complications and chronic diseases that impair the functional condition of patients with type 1 DM.
Collapse
|
48
|
Zhang H, Wang Y, Li J, Yu J, Pu J, Li L, Zhang H, Zhang S, Peng G, Yang F, Liu P. Proteome of skeletal muscle lipid droplet reveals association with mitochondria and apolipoprotein a-I. J Proteome Res 2011; 10:4757-68. [PMID: 21870882 DOI: 10.1021/pr200553c] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The lipid droplet (LD) is a universal organelle governing the storage and turnover of neutral lipids. Mounting evidence indicates that elevated intramuscular triglyceride (IMTG) in skeletal muscle LDs is closely associated with insulin resistance and Type 2 Diabetes Mellitus (T2DM). Therefore, the identification of the skeletal muscle LD proteome will provide some clues to dissect the mechanism connecting IMTG with T2DM. In the present work, we identified 324 LD-associated proteins in mouse skeletal muscle LDs through mass spectrometry analysis. Besides lipid metabolism and membrane traffic proteins, a remarkable number of mitochondrial proteins were observed in the skeletal muscle LD proteome. Furthermore, imaging by fluorescence microscopy and transmission electronic microscopy (TEM) directly demonstrated that mitochondria closely adhere to LDs in vivo. Moreover, our results revealed for the first time that apolipoprotein A-I (apo A-I), the principal apolipoprotein of high density lipoprotein (HDL) particles, was also localized on skeletal muscle LDs. Further studies verified that apo A-I was expressed endogenously by skeletal muscle cells. In conclusion, we report the protein composition and characterization of skeletal muscle LDs and describe a novel LD-associated protein, apo A-I.
Collapse
Affiliation(s)
- Huina Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101, China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Rab18 dynamics in adipocytes in relation to lipogenesis, lipolysis and obesity. PLoS One 2011; 6:e22931. [PMID: 21829560 PMCID: PMC3145781 DOI: 10.1371/journal.pone.0022931] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 07/06/2011] [Indexed: 02/03/2023] Open
Abstract
Lipid droplets (LDs) are organelles that coordinate lipid storage and mobilization, both processes being especially important in cells specialized in managing fat, the adipocytes. Proteomic analyses of LDs have consistently identified the small GTPase Rab18 as a component of the LD coat. However, the specific contribution of Rab18 to adipocyte function remains to be elucidated. Herein, we have analyzed Rab18 expression, intracellular localization and function in relation to the metabolic status of adipocytes. We show that Rab18 production increases during adipogenic differentiation of 3T3-L1 cells. In addition, our data show that insulin induces, via phosphatidylinositol 3-kinase (PI3K), the recruitment of Rab18 to the surface of LDs. Furthermore, Rab18 overexpression increased basal lipogenesis and Rab18 silencing impaired the lipogenic response to insulin, thereby suggesting that this GTPase promotes fat accumulation in adipocytes. On the other hand, studies of the β-adrenergic receptor agonist isoproterenol confirmed and extended previous evidence for the participation of Rab18 in lipolysis. Together, our data support the view that Rab18 is a common mediator of lipolysis and lipogenesis and suggests that the endoplasmic reticulum (ER) is the link that enables Rab18 action on these two processes. Finally, we describe, for the first time, the presence of Rab18 in human adipose tissue, wherein the expression of this GTPase exhibits sex- and depot-specific differences and is correlated to obesity. Taken together, these findings indicate that Rab18 is involved in insulin-mediated lipogenesis, as well as in β-adrenergic-induced lipolysis, likely facilitating interaction of LDs with ER membranes and the exchange of lipids between these compartments. A role for Rab18 in the regulation of adipocyte biology under both normal and pathological conditions is proposed.
Collapse
|
50
|
Abstract
The lipid droplet (LD), an organelle that exists ubiquitously in various organisms, from bacteria to mammals, has attracted much attention from both medical and cell biology fields. The LD in white adipocytes is often treated as the prototype LD, but is rather a special example, considering that its size, intracellular localization and molecular composition are vastly different from those of non-adipocyte LDs. These differences confer distinct properties on adipocyte and non-adipocyte LDs. In this article, we address the current understanding of LDs by discussing the differences between adipocyte and non-adipocyte LDs.
Collapse
Affiliation(s)
- Michitaka Suzuki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | | | | | | |
Collapse
|