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Brodsky JL, Iyer A, Fortounas KI, Fisher EA. The emerging role of fat-inducing transcript 2 in endoplasmic reticulum proteostasis and lipoprotein biogenesis. Curr Opin Lipidol 2024; 35:248-252. [PMID: 39172716 PMCID: PMC11387134 DOI: 10.1097/mol.0000000000000943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/24/2024]
Abstract
PURPOSE OF REVIEW This review examines the evolving role of the fat-inducing transcript 2 (FIT2) protein in lipid droplet (LD) biology and its broader implications in cellular physiology and disease. With recent advancements in understanding FIT2 function across various model systems, this review provides a timely synthesis of its mechanisms and physiological significance. RECENT FINDINGS FIT2, an endoplasmic reticulum (ER)-resident protein, has been established as a critical regulator of LD formation in diverse organisms, from yeast to mammals. It facilitates LD biogenesis by sequestering diacylglycerol (DAG) and potentially influencing ER membrane dynamics. Beyond its role in lipid metabolism, FIT2 intersects with the ER-associated degradation (ERAD), is critical for protein homeostasis, and is linked to the unfolded protein response (UPR). Dysregulation of FIT2 has also been linked to metabolic disorders such as insulin resistance and lipodystrophy, highlighting its clinical relevance. SUMMARY Insights into FIT2 function underscore its pivotal role in LD formation and lipid homeostasis. Understanding its involvement in ER proteostasis and very low density lipoprotein biogenesis has broad implications for metabolic diseases and cancer. Therapeutic strategies targeting FIT2 may offer novel approaches to modulate lipid metabolism and mitigate associated pathologies. Further research is needed to elucidate the full spectrum of FIT2's interactions within cellular lipid and protein networks, potentially uncovering new therapeutic avenues for metabolic and ER stress-related disorders.
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Affiliation(s)
- Jeffrey L Brodsky
- Department of Biological Sciences
- Center for Protein Conformational Diseases, University of Pittsburgh, Pittsburgh, Pennsylvania
| | | | - Konstantinos I Fortounas
- Division of Cardiology and the Department of Medicine, NYU School of Medicine
- Cardiovascular Research Center and the Marc and Ruti Bell Program in Vascular Biology, NYU School of Medicine, New York, New York, New York, USA
| | - Edward A Fisher
- Division of Cardiology and the Department of Medicine, NYU School of Medicine
- Cardiovascular Research Center and the Marc and Ruti Bell Program in Vascular Biology, NYU School of Medicine, New York, New York, New York, USA
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2
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Graff J, Schneiter R. FIT2 proteins and lipid droplet emergence, an interplay between phospholipid synthesis, surface tension, and membrane curvature. Front Cell Dev Biol 2024; 12:1422032. [PMID: 38872930 PMCID: PMC11169642 DOI: 10.3389/fcell.2024.1422032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Accepted: 05/06/2024] [Indexed: 06/15/2024] Open
Abstract
Lipid droplets (LDs) serve as intracellular compartments primarily dedicated to the storage of metabolic energy in the form of neutral lipids. The processes that regulate and control LD biogenesis are being studied extensively and are gaining significance due to their implications in major metabolic disorders, including type 2 diabetes and obesity. A protein of particular interest is Fat storage-Inducing Transmembrane 2 (FIT2), which affects the emergence step of LD biogenesis. Instead of properly emerging towards the cytosol, LDs in FIT2-deficient cells remain embedded within the membrane of the endoplasmic reticulum (ER). In vitro studies revealed the ability of FIT2 to bind both di- and triacylglycerol (DAG/TAG), key players in lipid storage, and its activity to cleave acyl-CoA. However, the translation of these in vitro functions to the observed embedding of LDs in FIT2 deficient cells remains to be established. To understand the role of FIT2 in vivo, we discuss the parameters that affect LD emergence. Our focus centers on the role that membrane curvature and surface tension play in LD emergence, as well as the impact that the lipid composition exerts on these key parameters. In addition, we discuss hypotheses on how FIT2 could function locally to modulate lipids at sites of LD emergence.
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Affiliation(s)
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Fribourg, Switzerland
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3
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Klug YA, Ferreira JV, Carvalho P. A unifying mechanism for seipin-mediated lipid droplet formation. FEBS Lett 2024; 598:1116-1126. [PMID: 38785192 PMCID: PMC11421547 DOI: 10.1002/1873-3468.14825] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/13/2024] [Accepted: 01/23/2024] [Indexed: 05/25/2024]
Abstract
Lipid droplets (LDs) are dynamic organelles essential for cellular lipid homeostasis. Assembly of LDs occurs in the endoplasmic reticulum (ER), and the conserved ER membrane protein seipin emerged as a key player in this process. Here, we review recent advances provided by structural, biochemical, and in silico analysis that revealed mechanistic insights into the molecular role of the seipin complexes and led to an updated model for LD biogenesis. We further discuss how other ER components cooperate with seipin during LD biogenesis. Understanding the molecular mechanisms underlying seipin-mediated LD assembly is important to uncover the fundamental aspects of lipid homeostasis and organelle biogenesis and to provide hints on the pathogenesis of lipid storage disorders.
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Affiliation(s)
- Yoel A Klug
- Sir William Dunn School of Pathology, University of Oxford, UK
| | | | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, UK
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4
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Wang H, Nikain C, Amengual J, La Forest M, Yu Y, Wang MC, Watts R, Lehner R, Qiu Y, Cai M, Kurland IJ, Goldberg IJ, Rajan S, Hussain MM, Brodsky JL, Fisher EA. FITM2 deficiency results in ER lipid accumulation, ER stress, reduced apolipoprotein B lipidation, and VLDL triglyceride secretion in vitro and in mouse liver. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.05.570183. [PMID: 38106013 PMCID: PMC10723279 DOI: 10.1101/2023.12.05.570183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Objectives Triglyceride (TG) association with apolipoprotein B100 (apoB100) serves to form very low density lipoproteins (VLDL) in the liver. The repertoire of factors that facilitate this association is incompletely defined. FITM2, an integral endoplasmic reticulum (ER) protein, was originally discovered as a factor participating in cytoplasmic lipid droplets (LDs) in tissues that do not form VLDL. We hypothesized that in the liver, in addition to promoting cytosolic LD formation, FITM2 would also transfer TG from its site of synthesis in the ER membrane to nascent VLDL particles within the ER lumen. Methods Experiments were conducted using a rat hepatic cell line (McArdle-RH7777, or McA cells), an established model of mammalian lipoprotein metabolism, and mice. FITM2 expression was reduced using siRNA in cells and by liver specific cre-recombinase mediated deletion of the Fitm2 gene in mice. Effects of FITM2 deficiency on VLDL assembly and secretion in vitro and in vivo were measured by multiple methods, including density gradient ultracentrifugation, chromatography, mass spectrometry, simulated Raman spectroscopy (SRS) microscopy, sub-cellular fractionation, immunoprecipitation, immunofluorescence, and electron microscopy. Main findings 1) FITM2-deficient hepatic cells in vitro and in vivo secrete TG-depleted VLDL particles, but the number of particles is unchanged compared to controls; 2) FITM2 deficiency in mice on a high fat diet (HFD) results in decreased plasma TG levels. The number of apoB100-containing lipoproteins remains similar, but shift from VLDL to LDL density; 3) Both in vitro and in vivo , when TG synthesis is stimulated and FITM2 is deficient, TG accumulates in the ER, and despite its availability this pool is unable to fully lipidate apoB100 particles; 4) FITM2 deficiency disrupts ER morphology and results in ER stress. Principal conclusions The results suggest that FITM2 contributes to VLDL lipidation, especially when newly synthesized hepatic TG is in abundance. In addition to its fundamental importance in VLDL assembly, the results also suggest that under dysmetabolic conditions, FITM2 may be a limiting factor that ultimately contributes to non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH).
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5
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Enkler L, Szentgyörgyi V, Pennauer M, Prescianotto-Baschong C, Riezman I, Wiesyk A, Avraham RE, Spiess M, Zalckvar E, Kucharczyk R, Riezman H, Spang A. Arf1 coordinates fatty acid metabolism and mitochondrial homeostasis. Nat Cell Biol 2023; 25:1157-1172. [PMID: 37400497 PMCID: PMC10415182 DOI: 10.1038/s41556-023-01180-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 06/05/2023] [Indexed: 07/05/2023]
Abstract
Lipid mobilization through fatty acid β-oxidation is a central process essential for energy production during nutrient shortage. In yeast, this catabolic process starts in the peroxisome from where β-oxidation products enter mitochondria and fuel the tricarboxylic acid cycle. Little is known about the physical and metabolic cooperation between these organelles. Here we found that expression of fatty acid transporters and of the rate-limiting enzyme involved in β-oxidation is decreased in cells expressing a hyperactive mutant of the small GTPase Arf1, leading to an accumulation of fatty acids in lipid droplets. Consequently, mitochondria became fragmented and ATP synthesis decreased. Genetic and pharmacological depletion of fatty acids phenocopied the arf1 mutant mitochondrial phenotype. Although β-oxidation occurs in both mitochondria and peroxisomes in mammals, Arf1's role in fatty acid metabolism is conserved. Together, our results indicate that Arf1 integrates metabolism into energy production by regulating fatty acid storage and utilization, and presumably organelle contact sites.
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Affiliation(s)
| | | | | | | | - Isabelle Riezman
- Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Aneta Wiesyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Reut Ester Avraham
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | | | - Einat Zalckvar
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Roza Kucharczyk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Howard Riezman
- Department of Biochemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | - Anne Spang
- Biozentrum, University of Basel, Basel, Switzerland.
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6
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Wang Y, Jiang Z, Qin A, Wang F, Chang E, Liu Y, Nie W, Tan C, Yuan Y, Dong Y, Huang R, Jia Z, Wang J. Population Structure, Genetic Diversity and Candidate Genes for the Adaptation to Environmental Stress in Picea koraiensis. PLANTS (BASEL, SWITZERLAND) 2023; 12:1266. [PMID: 36986954 PMCID: PMC10055018 DOI: 10.3390/plants12061266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/07/2023] [Accepted: 03/08/2023] [Indexed: 06/19/2023]
Abstract
Picea koraiensis is major silvicultural and timber species in northeast China, and its distribution area is an important transition zone for genus spruce migration. The degree of intraspecific differentiation of P. koraiensis is high, but population structure and differentiation mechanisms are not clear. In this study, 523,761 single nucleotide polymorphisms (SNPs) were identified in 113 individuals from 9 populations of P. koraiensis by genotyping-by-sequencing (GBS). Population genomic analysis showed that P. koraiensis was divided into three geoclimatic regions: Great Khingan Mountains climatic region, Lesser Khingan Mountains climatic region, and Changbai Mountain climatic region. Mengkeshan (MKS) population on the northern edge of the distribution area and Wuyiling (WYL) population located in the mining area are two highly differentiated groups. Selective sweep analysis showed that MKS and WYL populations had 645 and 1126 selected genes, respectively. Genes selected in the MKS population were associated with flowering and photomorphogenesis, cellular response to water deficit, and glycerophospholipid metabolism; genes selected in the WYL population were associated with metal ion transport, biosynthesis of macromolecules, and DNA repair. Climatic factors and heavy metal stress drives divergence in MKS and WYL populations, respectively. Our findings provide insights into adaptive divergence mechanisms in Picea and will contribute to molecular breeding studies.
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Affiliation(s)
- Ya Wang
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
| | - Zeping Jiang
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
| | - Aili Qin
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
| | - Fude Wang
- Forestry Research Institute in Heilongjiang Province, Harbin 150081, China
| | - Ermei Chang
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
| | - Yifu Liu
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
| | - Wen Nie
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
| | - Cancan Tan
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
| | - Yanchao Yuan
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
| | - Yao Dong
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
| | - Ruizhi Huang
- Key Laboratory of Forest Ecology and Environment of National Forestry and Grassland Administration, Ecology and Nature Conservation Institute, Chinese Academy of Forestry, Beijing 100091, China
| | - Zirui Jia
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
| | - Junhui Wang
- State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
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7
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Celik C, Lee SYT, Yap WS, Thibault G. Endoplasmic reticulum stress and lipids in health and diseases. Prog Lipid Res 2023; 89:101198. [PMID: 36379317 DOI: 10.1016/j.plipres.2022.101198] [Citation(s) in RCA: 37] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/03/2022] [Accepted: 11/09/2022] [Indexed: 11/14/2022]
Abstract
The endoplasmic reticulum (ER) is a complex and dynamic organelle that regulates many cellular pathways, including protein synthesis, protein quality control, and lipid synthesis. When one or multiple ER roles are dysregulated and saturated, the ER enters a stress state, which, in turn, activates the highly conserved unfolded protein response (UPR). By sensing the accumulation of unfolded proteins or lipid bilayer stress (LBS) at the ER, the UPR triggers pathways to restore ER homeostasis and eventually induces apoptosis if the stress remains unresolved. In recent years, it has emerged that the UPR works intimately with other cellular pathways to maintain lipid homeostasis at the ER, and so does at cellular levels. Lipid distribution, along with lipid anabolism and catabolism, are tightly regulated, in part, by the ER. Dysfunctional and overwhelmed lipid-related pathways, independently or in combination with ER stress, can have reciprocal effects on other cellular functions, contributing to the development of diseases. In this review, we summarize the current understanding of the UPR in response to proteotoxic stress and LBS and the breadth of the functions mitigated by the UPR in different tissues and in the context of diseases.
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Affiliation(s)
- Cenk Celik
- School of Biological Sciences, Nanyang Technological University, Singapore
| | | | - Wei Sheng Yap
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Guillaume Thibault
- School of Biological Sciences, Nanyang Technological University, Singapore; Mechanobiology Institute, National University of Singapore, Singapore; Institute of Molecular and Cell Biology, A*STAR, Singapore.
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8
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Wang G, Chen A, Wu Y, Wang D, Chang C, Yu G. Fat storage-inducing transmembrane proteins: beyond mediating lipid droplet formation. Cell Mol Biol Lett 2022; 27:98. [DOI: 10.1186/s11658-022-00391-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 09/23/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractFat storage-inducing transmembrane proteins (FITMs) were initially identified in 2007 as members of a conserved endoplasmic reticulum (ER) resident transmembrane protein gene family, and were found to be involved in lipid droplet (LD) formation. Recently, several studies have further demonstrated that the ability of FITMs to directly bind to triglyceride and diacylglycerol, and the diphosphatase activity of hydrolyzing fatty acyl-CoA, might enable FITMs to maintain the formation of lipid droplets, engage in lipid metabolism, and protect against cellular stress. Based on the distribution of FITMs in tissues and their important roles in lipid droplet biology and lipid metabolism, it was discovered that FITMs were closely related to muscle development, adipocyte differentiation, and energy metabolism. Accordingly, the abnormal expression of FITMs was not only associated with type 2 diabetes and lipodystrophy, but also with cardiac disease and several types of cancer. This study reviews the structure, distribution, expression regulation, and functionality of FITMs and their potential relationships with various metabolic diseases, hoping to provide inspiration for fruitful research directions and applications of FITM proteins. Moreover, this review will provide an important theoretical basis for the application of FITMs in the diagnosis and treatment of related diseases.
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9
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Zheng X, Ho QWC, Chua M, Stelmashenko O, Yeo XY, Muralidharan S, Torta F, Chew EGY, Lian MM, Foo JN, Jung S, Wong SH, Tan NS, Tong N, Rutter GA, Wenk MR, Silver DL, Berggren PO, Ali Y. Destabilization of β Cell FIT2 by saturated fatty acids alter lipid droplet numbers and contribute to ER stress and diabetes. Proc Natl Acad Sci U S A 2022; 119:e2113074119. [PMID: 35254894 PMCID: PMC8931238 DOI: 10.1073/pnas.2113074119] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/29/2022] [Indexed: 02/05/2023] Open
Abstract
SignificanceWith obesity on the rise, there is a growing appreciation for intracellular lipid droplet (LD) regulation. Here, we show how saturated fatty acids (SFAs) reduce fat storage-inducing transmembrane protein 2 (FIT2)-facilitated, pancreatic β cell LD biogenesis, which in turn induces β cell dysfunction and death, leading to diabetes. This mechanism involves direct acylation of FIT2 cysteine residues, which then marks the FIT2 protein for endoplasmic reticulum (ER)-associated degradation. Loss of β cell FIT2 and LDs reduces insulin secretion, increases intracellular ceramides, stimulates ER stress, and exacerbates diet-induced diabetes in mice. While palmitate and stearate degrade FIT2, unsaturated fatty acids such as palmitoleate and oleate do not, results of which extend to nutrition and diabetes.
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Affiliation(s)
- Xiaofeng Zheng
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- Singapore Eye Research Institute, Singapore General Hospital, S168751, Singapore
- Department of Endocrinology and Metabolism, Center for Diabetes and Metabolism Research, West China Hospital, Sichuan University, Chengdu 610041, People’s Republic of China
| | - Qing Wei Calvin Ho
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
| | - Minni Chua
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
| | - Olga Stelmashenko
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- Singapore Eye Research Institute, Singapore General Hospital, S168751, Singapore
| | - Xin Yi Yeo
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, S138667, Singapore
- Department of Psychological Medicine, Yong Loo Lin School of Medicine, National University of Singapore, S119228, Singapore
| | - Sneha Muralidharan
- Singapore Lipidomics Incubator, Department of Medicine, National University of Singapore, S117456, Singapore
| | - Federico Torta
- Singapore Lipidomics Incubator, Department of Biochemistry, Life Sciences Institute and Yong Loo Lin School of Medicine, National University of Singapore, S117456, Singapore
| | - Elaine Guo Yan Chew
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- Human Genetics, A*STAR, Genome Institute of Singapore, S138672, Singapore
| | - Michelle Mulan Lian
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- Human Genetics, A*STAR, Genome Institute of Singapore, S138672, Singapore
| | - Jia Nee Foo
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- Human Genetics, A*STAR, Genome Institute of Singapore, S138672, Singapore
| | - Sangyong Jung
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, S138667, Singapore
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, S117593, Singapore
| | - Sunny Hei Wong
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
| | - Nguan Soon Tan
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- School of Biological Sciences, Nanyang Technological University Singapore, S637551, Singapore
| | - Nanwei Tong
- Department of Endocrinology and Metabolism, Center for Diabetes and Metabolism Research, West China Hospital, Sichuan University, Chengdu 610041, People’s Republic of China
| | - Guy A. Rutter
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Department of Metabolism, Digestion, and Reproduction, Imperial College London, London SW7 2AZ, United Kingdom
- Le Centre de recherche du Centre hospitalier de l’Université de Montréal (CR-CHUM), University of Montréal, Montréal, QC H2X 0A9, Canada
| | - Markus R. Wenk
- Singapore Lipidomics Incubator, Department of Biochemistry, Life Sciences Institute and Yong Loo Lin School of Medicine, National University of Singapore, S117456, Singapore
| | - David L. Silver
- Signature Research Program in Cardiovascular and Metabolic Disorders, Duke–National University of Singapore Graduate Medical School, S169857, Singapore
| | - Per-Olof Berggren
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- Singapore Eye Research Institute, Singapore General Hospital, S168751, Singapore
- Department of Endocrinology and Metabolism, Center for Diabetes and Metabolism Research, West China Hospital, Sichuan University, Chengdu 610041, People’s Republic of China
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden
| | - Yusuf Ali
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, S308232, Singapore
- Singapore Eye Research Institute, Singapore General Hospital, S168751, Singapore
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10
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Liao PC, Yang EJ, Borgman T, Boldogh IR, Sing CN, Swayne TC, Pon LA. Touch and Go: Membrane Contact Sites Between Lipid Droplets and Other Organelles. Front Cell Dev Biol 2022; 10:852021. [PMID: 35281095 PMCID: PMC8908909 DOI: 10.3389/fcell.2022.852021] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 02/03/2022] [Indexed: 12/26/2022] Open
Abstract
Lipid droplets (LDs) have emerged not just as storage sites for lipids but as central regulators of metabolism and organelle quality control. These critical functions are achieved, in part, at membrane contact sites (MCS) between LDs and other organelles. MCS are sites of transfer of cellular constituents to or from LDs for energy mobilization in response to nutrient limitations, as well as LD biogenesis, expansion and autophagy. Here, we describe recent findings on the mechanisms underlying the formation and function of MCS between LDs and mitochondria, ER and lysosomes/vacuoles and the role of the cytoskeleton in promoting LD MCS through its function in LD movement and distribution in response to environmental cues.
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Affiliation(s)
- Pin-Chao Liao
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan
| | - Emily J. Yang
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
| | - Taylor Borgman
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
| | - Istvan R. Boldogh
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, United States
| | - Cierra N. Sing
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
| | - Theresa C. Swayne
- Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, United States
| | - Liza A. Pon
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY, United States
- Institute of Human Nutrition, Columbia University Irving Medical Center, New York, NY, United States
- *Correspondence: Liza A. Pon,
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11
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Chen F, Yan B, Ren J, Lyu R, Wu Y, Guo Y, Li D, Zhang H, Hu J. FIT2 organizes lipid droplet biogenesis with ER tubule-forming proteins and septins. J Cell Biol 2021; 220:211999. [PMID: 33861319 PMCID: PMC8056755 DOI: 10.1083/jcb.201907183] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/29/2020] [Accepted: 02/09/2021] [Indexed: 12/20/2022] Open
Abstract
Lipid droplets (LDs) are critical for lipid storage and energy metabolism. LDs form in the endoplasmic reticulum (ER). However, the molecular basis for LD biogenesis remains elusive. Here, we show that fat storage–inducing transmembrane protein 2 (FIT2) interacts with ER tubule-forming proteins Rtn4 and REEP5. The association is mainly transmembrane domain based and stimulated by oleic acid. Depletion of ER tubule-forming proteins decreases the number and size of LDs in cells and Caenorhabditis elegans, mimicking loss of FIT2. Through cytosolic loops, FIT2 binds to cytoskeletal protein septin 7, an interaction that is also required for normal LD biogenesis. Depletion of ER tubule-forming proteins or septins delays nascent LD formation. In addition, FIT2-interacting proteins are up-regulated during adipocyte differentiation, and ER tubule-forming proteins, septin 7, and FIT2 are transiently enriched at LD formation sites. Thus, FIT2-mediated nascent LD biogenesis is facilitated by ER tubule-forming proteins and septins.
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Affiliation(s)
- Fang Chen
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Bing Yan
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jie Ren
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Rui Lyu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yanfang Wu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yuting Guo
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Junjie Hu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
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First person – Wei Sheng Yap. J Cell Sci 2020. [DOI: 10.1242/jcs.256016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABSTRACT
First Person is a series of interviews with the first authors of a selection of papers published Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Wei Sheng Yap is first author on ‘The yeast FIT2 homologs are necessary to maintain cellular proteostasis and membrane lipid homeostasis’, published in JCS. Wei Sheng works in the lab of Guillaume Thibault in the School of Biological Sciences, Nanyang Technological University, Singapore, studying the interplay between the proteostasis network and lipid homeostasis.
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