1
|
Kim S. All-Atom Membrane Builder via Multiscale Simulation. J Chem Inf Model 2024. [PMID: 39250520 DOI: 10.1021/acs.jcim.4c01059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
I present an automated and flexible tool designed for constructing bilayer membranes at all-atom (AA) resolution. The builder initiates the construction and equilibration of bilayer membranes at Martini coarse-grained (CG) resolution, followed by resolution enhancement to the atomic level using the accompanying backmapping tool. Notably, this tool enables users to create bilayer membranes with user-defined lipid compositions and protein structures, while also offering the flexibility to accommodate new lipid types. To assess the simplicity and robustness of the tool, I demonstrate the construction of several membranes incorporating protein structures. The tool is freely available at github.com/ksy141/mstool.
Collapse
Affiliation(s)
- Siyoung Kim
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
| |
Collapse
|
2
|
Li X, Gamuyao R, Wu ML, Cho WJ, King SV, Petersen R, Stabley DR, Lindow C, Climer LK, Shirinifard A, Ferrara F, Throm RE, Robinson CG, Zhou Y, Carisey AF, Tebo AG, Chang CL. A fluorogenic complementation tool kit for interrogating lipid droplet-organelle interaction. J Cell Biol 2024; 223:e202311126. [PMID: 38949658 PMCID: PMC11215687 DOI: 10.1083/jcb.202311126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 04/24/2024] [Accepted: 05/31/2024] [Indexed: 07/02/2024] Open
Abstract
Contact sites between lipid droplets and other organelles are essential for cellular lipid and energy homeostasis upon metabolic demands. Detection of these contact sites at the nanometer scale over time in living cells is challenging. We developed a tool kit for detecting contact sites based on fluorogen-activated bimolecular complementation at CONtact sites, FABCON, using a reversible, low-affinity split fluorescent protein, splitFAST. FABCON labels contact sites with minimal perturbation to organelle interaction. Via FABCON, we quantitatively demonstrated that endoplasmic reticulum (ER)- and mitochondria (mito)-lipid droplet contact sites are dynamic foci in distinct metabolic conditions, such as during lipid droplet biogenesis and consumption. An automated analysis pipeline further classified individual contact sites into distinct subgroups based on size, likely reflecting differential regulation and function. Moreover, FABCON is generalizable to visualize a repertoire of organelle contact sites including ER-mito. Altogether, FABCON reveals insights into the dynamic regulation of lipid droplet-organelle contact sites and generates new hypotheses for further mechanistical interrogation during metabolic regulation.
Collapse
Affiliation(s)
- Xiao Li
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Rico Gamuyao
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Ming-Lun Wu
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Woo Jung Cho
- Cell and Tissue Imaging Center, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Sharon V. King
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - R.A. Petersen
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Daniel R. Stabley
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Caleb Lindow
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Leslie K. Climer
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Abbas Shirinifard
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Francesca Ferrara
- Vector Production and Development Laboratory, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Robert E. Throm
- Vector Production and Development Laboratory, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Camenzind G. Robinson
- Cell and Tissue Imaging Center, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Yiwang Zhou
- Department of Biostatistics, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Alexandre F. Carisey
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Alison G. Tebo
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Chi-Lun Chang
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| |
Collapse
|
3
|
Holzhütter HG. Dynamical modelling of lipid droplet formation suggests a key function of membrane phospholipids. FEBS J 2024. [PMID: 39132700 DOI: 10.1111/febs.17238] [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: 03/15/2024] [Revised: 06/10/2024] [Accepted: 07/23/2024] [Indexed: 08/13/2024]
Abstract
Cells store triacylglycerol (TAG) within lipid droplets (LDs). A dynamic model describing complete LD formation at the endoplasmic reticulum (ER) membrane does not yet exist. A biochemical-biophysical model of LD synthesis is proposed. It describes the time-dependent accumulation of TAG in the ER membrane as the formation of a potential LD (pLD) bounded by spherical caps of the inner and outer monolayers of the membrane. The expansion rate of the pLD depends on the TAG supply, the elastic properties of the ER membrane, and the recruitment of phospholipids (PLs) to the cap-covering monolayers. Model simulations provided the following insights: (a) Marginal differences in the surface tension of the cap monolayers are sufficient to fully drive the expansion of the pLD towards the cytosol or lumen. (b) Selective reduction of PL supply to the luminal monolayer ensures stable formation of cytosolic LDs, irrespective of variations in the elasto-mechanical properties of the ER membrane. (c) The rate of TAG supply to the cytosolic monolayer has a major effect on the size and maturation time of LDs but has no significant effect on the TAG export per individual LD. The recruitment of additional PLs to the cap monolayers of pLDs critically controls the budding direction, size, and maturation time of LDs. The ability of cells to acquire additional LD initiation sites appears to be key to coping with acutely high levels of potentially toxic free fatty acids.
Collapse
Affiliation(s)
- Hermann-Georg Holzhütter
- Institute of Biochemistry, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Germany
| |
Collapse
|
4
|
McClure JJ, McIlroy GD, Symons RA, Clark SM, Cunningham I, Han W, Kania K, Colella F, Rochford JJ, De Bari C, Roelofs AJ. Disentangling the detrimental effects of local from systemic adipose tissue dysfunction on articular cartilage in the knee. Osteoarthritis Cartilage 2024:S1063-4584(24)01312-8. [PMID: 39103079 DOI: 10.1016/j.joca.2024.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 07/11/2024] [Accepted: 07/12/2024] [Indexed: 08/07/2024]
Abstract
OBJECTIVE Obesity increases osteoarthritis (OA) risk due to adipose tissue dysfunction with associated metabolic syndrome and excess weight. Lipodystrophy syndromes exhibit systemic metabolic and inflammatory abnormalities similar to obesity without biomechanical overloading. Here, we used lipodystrophy mouse models to investigate the effects of systemic versus intra-articular adipose tissue dysfunction on the knee. METHODS Intra-articular adipose tissue development was studied using reporter mice. Mice with selective lipodystrophy of intra-articular adipose tissue were generated by conditional knockout (cKO) of Bscl2 in Gdf5-lineage cells, and compared with whole-body Bscl2 knockout (KO) mice with generalised lipodystrophy and associated systemic metabolic dysfunction. OA was induced by surgically destabilising the medial meniscus (DMM) and obesity by high-fat diet (HFD). Gene expression was analysed by quantitative RT-PCR and tissues were analysed histologically. RESULTS The infrapatellar fat pad (IFP), in contrast to overlying subcutaneous adipose tissue, developed from a template established from the Gdf5-expressing joint interzone during late embryogenesis, and was populated shortly after birth by adipocytes stochastically arising from Pdgfrα-expressing Gdf5-lineage progenitors. While female Bscl2 KO mice with generalised lipodystrophy developed spontaneous knee cartilage damage, Bscl2 cKO mice with intra-articular lipodystrophy did not, despite the presence of synovial hyperplasia and inflammation of the residual IFP. Furthermore, male Bscl2 cKO mice showed no worse cartilage damage after DMM. However, female Bscl2 cKO mice showed increased susceptibility to the cartilage-damaging effects of HFD-induced obesity. CONCLUSION Our findings emphasise the prevalent role of systemic metabolic and inflammatory effects in impairing cartilage homeostasis, with a modulatory role for intra-articular adipose tissue.
Collapse
Affiliation(s)
- Jessica J McClure
- Arthritis & Regenerative Medicine Laboratory, Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - George D McIlroy
- The Rowett Institute and Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Rebecca A Symons
- Arthritis & Regenerative Medicine Laboratory, Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Susan M Clark
- Arthritis & Regenerative Medicine Laboratory, Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Iain Cunningham
- Arthritis & Regenerative Medicine Laboratory, Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Weiping Han
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A⁎STAR), Singapore
| | - Karolina Kania
- Arthritis & Regenerative Medicine Laboratory, Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Fabio Colella
- Arthritis & Regenerative Medicine Laboratory, Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Justin J Rochford
- The Rowett Institute and Aberdeen Cardiovascular and Diabetes Centre, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Cosimo De Bari
- Arthritis & Regenerative Medicine Laboratory, Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Anke J Roelofs
- Arthritis & Regenerative Medicine Laboratory, Centre for Arthritis and Musculoskeletal Health, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
| |
Collapse
|
5
|
Tang Y, Majewska M, Leß B, Mehmeti I, Wollnitzke P, Semleit N, Levkau B, Saba JD, van Echten-Deckert G, Gurgul-Convey E. The fate of intracellular S1P regulates lipid droplet turnover and lipotoxicity in pancreatic beta-cells. J Lipid Res 2024; 65:100587. [PMID: 38950680 PMCID: PMC11345310 DOI: 10.1016/j.jlr.2024.100587] [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: 12/19/2023] [Revised: 06/07/2024] [Accepted: 06/22/2024] [Indexed: 07/03/2024] Open
Abstract
Lipotoxicity has been considered the main cause of pancreatic beta-cell failure during type 2 diabetes development. Lipid droplets (LD) are believed to regulate the beta-cell sensitivity to free fatty acids (FFA), but the underlying molecular mechanisms are largely unclear. Accumulating evidence points, however, to an important role of intracellular sphingosine-1-phosphate (S1P) metabolism in lipotoxicity-mediated disturbances of beta-cell function. In the present study, we compared the effects of an increased irreversible S1P degradation (S1P-lyase, SPL overexpression) with those associated with an enhanced S1P recycling (overexpression of S1P phosphatase 1, SGPP1) on LD formation and lipotoxicity in rat INS1E beta-cells. Interestingly, although both approaches led to a reduced S1P concentration, they had opposite effects on the susceptibility to FFA. Overexpression of SGPP1 prevented FFA-mediated caspase-3 activation by a mechanism involving an enhanced lipid storage capacity and prevention of oxidative stress. In contrast, SPL overexpression limited LD biogenesis, content, and size, while accelerating lipophagy. This was associated with FFA-induced hydrogen peroxide formation, mitochondrial fragmentation, and dysfunction, as well as ER stress. These changes coincided with the upregulation of proapoptotic ceramides but were independent of lipid peroxidation rate. Also in human EndoC-βH1 beta-cells, suppression of SPL with simultaneous overexpression of SGPP1 led to a similar and even more pronounced LD phenotype as that in INS1E-SGPP1 cells. Thus, intracellular S1P turnover significantly regulates LD content and size and influences beta-cell sensitivity to FFA.
Collapse
Affiliation(s)
- Yadi Tang
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Mariola Majewska
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Britta Leß
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Ilir Mehmeti
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany
| | - Philipp Wollnitzke
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Nina Semleit
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Bodo Levkau
- Institute of Molecular Medicine III, University Hospital Düsseldorf and Heinrich Heine University, Düsseldorf, Germany
| | - Julie D Saba
- Division of Hematology/Oncology, Department of Pediatrics, University of California. San Francisco, Oakland, CA, USA
| | | | - Ewa Gurgul-Convey
- Institute of Clinical Biochemistry, Hannover Medical School, Hannover, Germany.
| |
Collapse
|
6
|
Wang CW, Chen RH, Chen YK. The lipid droplet assembly complex consists of seipin and four accessory factors in budding yeast. J Biol Chem 2024; 300:107534. [PMID: 38981533 PMCID: PMC11342095 DOI: 10.1016/j.jbc.2024.107534] [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: 02/29/2024] [Revised: 06/12/2024] [Accepted: 06/25/2024] [Indexed: 07/11/2024] Open
Abstract
Seipin, a crucial protein for cellular lipid droplet (LD) assembly, oligomerizes at the interface between the endoplasmic reticulum and LDs to facilitate neutral lipid packaging. Using proximity labeling, we identified four proteins-Ldo45, Ldo16, Tgl4, and Pln1-that are recruited to the vicinity of yeast seipin, the Sei1-Ldb16 complex, exclusively when seipin function is intact, hence termed seipin accessory factors. Localization studies identified Tgl4 at the endoplasmic reticulum-LD contact site, in contrast to Ldo45, Ldo16, and Pln1 at the LD surface. Cells with compromised seipin function resulted in uneven distribution of these proteins with aberrant LDs, supporting a central role of seipin in orchestrating their association with the LD. Overexpression of any seipin accessory factor causes LD aggregation and affects a subset of LD protein distribution, highlighting the importance of their stoichiometry. Although single factor mutations show minor LD morphology changes, the combined mutations have additive effects. Lastly, we present evidence that seipin accessory factors assemble and interact with seipin in the absence of neutral lipids and undergo dynamical rearrangements during LD formation induction, with Ldo45 acting as a central hub recruiting other factors to interact with the seipin complex.
Collapse
Affiliation(s)
- Chao-Wen Wang
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan.
| | - Rey-Huei Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Yu-Kai Chen
- Department of Life Sciences, National Cheng Kung University, Tainan, Taiwan
| |
Collapse
|
7
|
Li C, Sun XN, Funcke JB, Vanharanta L, Joffin N, Li Y, Prasanna X, Paredes M, Joung C, Gordillo R, Vörös C, Kulig W, Straub L, Chen S, Velasco J, Cobb A, Padula DL, Wang MY, Onodera T, Varlamov O, Li Y, Liu C, Nawrocki AR, Zhao S, Oh DY, Wang ZV, Goodman JM, Wynn RM, Vattulainen I, Han Y, Ikonen E, Scherer PE. Adipogenin Dictates Adipose Tissue Expansion by Facilitating the Assembly of a Dodecameric Seipin Complex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.25.605195. [PMID: 39211078 PMCID: PMC11360994 DOI: 10.1101/2024.07.25.605195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
Adipogenin (Adig) is an evolutionarily conserved microprotein and is highly expressed in adipose tissues and testis. Here, we identify Adig as a critical regulator for lipid droplet formation in adipocytes. We determine that Adig interacts directly with seipin, leading to the formation of a rigid complex. We solve the structure of the seipin/Adig complex by Cryo-EM at 2.98Å overall resolution. Surprisingly, seipin can form two unique oligomers, undecamers and dodecamers. Adig selectively binds to the dodecameric seipin complex. We further find that Adig promotes seipin assembly by stabilizing and bridging adjacent seipin subunits. Functionally, Adig plays a key role in generating lipid droplets in adipocytes. In mice, inducible overexpression of Adig in adipocytes substantially increases fat mass, with enlarged lipid droplets. It also elevates thermogenesis during cold exposure. In contrast, inducible adipocyte-specific Adig knockout mice manifest aberrant lipid droplet formation in brown adipose tissues and impaired cold tolerance.
Collapse
|
8
|
Zhang Z, Yu Z, Liang D, Song K, Kong X, He M, Liao X, Huang Z, Kang A, Bai R, Ren Y. Roles of lipid droplets and related proteins in metabolic diseases. Lipids Health Dis 2024; 23:218. [PMID: 39030618 PMCID: PMC11264848 DOI: 10.1186/s12944-024-02212-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 07/11/2024] [Indexed: 07/21/2024] Open
Abstract
Lipid droplets (LDs), which are active organelles, derive from the monolayer membrane of the endoplasmic reticulum and encapsulate neutral lipids internally. LD-associated proteins like RAB, those in the PLIN family, and those in the CIDE family participate in LD formation and development, and they are active players in various diseases, organelles, and metabolic processes (i.e., obesity, non-alcoholic fatty liver disease, and autophagy). Our synthesis on existing research includes insights from the formation of LDs to their mechanisms of action, to provide an overview needed for advancing research into metabolic diseases and lipid metabolism.
Collapse
Affiliation(s)
- Zhongyang Zhang
- Department of Gastroenterology, Affiliated Hospital of North Sichuan Medical College, South Maoyuan Road, Shunqing District, Nanchong, Sichuan Province, 637000, China
- Institute of Hepatobiliary Pancreatic Intestinal Diseases, North Sichuan Medical College, Nanchong, 637000, China
| | - Zhenghang Yu
- Department of Gastroenterology, Affiliated Hospital of North Sichuan Medical College, South Maoyuan Road, Shunqing District, Nanchong, Sichuan Province, 637000, China
- Institute of Hepatobiliary Pancreatic Intestinal Diseases, North Sichuan Medical College, Nanchong, 637000, China
| | - Dianyuan Liang
- Department of Gastroenterology, Affiliated Hospital of North Sichuan Medical College, South Maoyuan Road, Shunqing District, Nanchong, Sichuan Province, 637000, China
- Institute of Hepatobiliary Pancreatic Intestinal Diseases, North Sichuan Medical College, Nanchong, 637000, China
| | - Ke Song
- Department of Gastroenterology, Affiliated Hospital of North Sichuan Medical College, South Maoyuan Road, Shunqing District, Nanchong, Sichuan Province, 637000, China
- Institute of Hepatobiliary Pancreatic Intestinal Diseases, North Sichuan Medical College, Nanchong, 637000, China
| | - Xiangxin Kong
- Department of Gastroenterology, Affiliated Hospital of North Sichuan Medical College, South Maoyuan Road, Shunqing District, Nanchong, Sichuan Province, 637000, China
- Institute of Hepatobiliary Pancreatic Intestinal Diseases, North Sichuan Medical College, Nanchong, 637000, China
| | - Ming He
- Department of Gastroenterology, Affiliated Hospital of North Sichuan Medical College, South Maoyuan Road, Shunqing District, Nanchong, Sichuan Province, 637000, China
| | - Xinxin Liao
- Institute of Hepatobiliary Pancreatic Intestinal Diseases, North Sichuan Medical College, Nanchong, 637000, China
| | - Ziyan Huang
- Institute of Hepatobiliary Pancreatic Intestinal Diseases, North Sichuan Medical College, Nanchong, 637000, China
| | - Aijia Kang
- Institute of Hepatobiliary Pancreatic Intestinal Diseases, North Sichuan Medical College, Nanchong, 637000, China
| | - Rubing Bai
- Department of Gastroenterology, Affiliated Hospital of North Sichuan Medical College, South Maoyuan Road, Shunqing District, Nanchong, Sichuan Province, 637000, China.
| | - Yixing Ren
- Department of Gastroenterology, Affiliated Hospital of North Sichuan Medical College, South Maoyuan Road, Shunqing District, Nanchong, Sichuan Province, 637000, China.
- General Surgery, Chengdu XinHua Hospital Affiliated to North Sichuan Medical College, Chengdu, 610000, China.
| |
Collapse
|
9
|
Kataoka-Hamai C. Triacylglycerol-droplet-induced bilayer spontaneous curvature in giant unilamellar vesicles. Biophys J 2024; 123:1857-1868. [PMID: 38822522 PMCID: PMC11267425 DOI: 10.1016/j.bpj.2024.05.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 04/05/2024] [Accepted: 05/29/2024] [Indexed: 06/03/2024] Open
Abstract
This study investigated the incorporation of triacylglycerol droplets in the bilayers of giant unilamellar vesicles (GUVs) using four triacylglycerols and four phosphatidylcholines by confocal laser scanning microscopy. The triacylglycerol droplets were incorporated between the monolayer leaflets of the GUVs. Among the spherical droplets protruding on only one side of the bilayers, the droplets bound to the outer leaflets outnumbered those bound to the inner leaflets. The more frequent droplet binding to the outer leaflet caused transbilayer asymmetry in the droplet surface density. A vesicle consisting of a single-bilayer spherical segment and a double-bilayer spherical segment was also observed. The yield of these vesicles was comparable with or higher than that of the droplet-incorporating GUVs for many of the phosphatidylcholine-triacylglycerol combinations. In a vesicle consisting of single-bilayer and double-bilayer segments, most of the triacylglycerol droplets were localized on the outermost membrane surface along the segment boundary and in the double-bilayer segment. To rationalize the formation of these vesicle structures, we propose that the transbilayer asymmetry in the droplet surface density induces spontaneous curvature of the bilayer, with the bilayer spontaneously bending away from the droplets. Energy calculations performed assuming the existence of spontaneous curvature of the bilayer corroborated the experimentally determined membrane shapes for the vesicles consisting of unilamellar and bilamellar regions.
Collapse
Affiliation(s)
- Chiho Kataoka-Hamai
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan.
| |
Collapse
|
10
|
Mallick K, Paul S, Banerjee S, Banerjee S. Lipid Droplets and Neurodegeneration. Neuroscience 2024; 549:13-23. [PMID: 38718916 DOI: 10.1016/j.neuroscience.2024.04.014] [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: 03/01/2024] [Revised: 04/19/2024] [Accepted: 04/25/2024] [Indexed: 05/15/2024]
Abstract
Energy metabolism in the brain has been considered one of the critical research areas of neuroscience for ages. One of the most vital parts of brain metabolism cascades is lipid metabolism, and fatty acid plays a crucial role in this process. The fatty acid breakdown process in mitochondria undergoes through a conserved pathway known as β-oxidation where acetyl-CoA and shorter fatty acid chains are produced along with a significant amount of energy molecule. Further, the complete breakdown of fatty acids occurs when they enter the mitochondrial oxidative phosphorylation. Cells store energy as neutral lipids in organelles known as Lipid Droplets (LDs) to prepare for variations in the availability of nutrients. Fatty acids are liberated by lipid droplets and are transported to various cellular compartments for membrane biogenesis or as an energy source. Current research shows that LDs are important in inflammation, metabolic illness, and cellular communication. Lipid droplet biology in peripheral organs like the liver and heart has been well investigated, while the brain's LDs have received less attention. Recently, there has been increased awareness of the existence and role of these dynamic organelles in the central nervous system, mainly connected to neurodegeneration. In this review, we discussed the role of beta-oxidation and lipid droplet formation in the oxidative phosphorylation process, which directly affects neurodegeneration through various pathways.
Collapse
Affiliation(s)
- Keya Mallick
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Kolkata, India.
| | - Shuchismita Paul
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Kolkata, India.
| | - Sayani Banerjee
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Kolkata, India.
| | - Sugato Banerjee
- Department of Pharmacology and Toxicology, National Institute of Pharmaceutical Education and Research, Kolkata, India.
| |
Collapse
|
11
|
Demirel-Yalciner T, Cetinkaya B, Sozen E, Ozer NK. Impact of Seipin in cholesterol mediated lipid droplet maturation; status of endoplasmic reticulum stress and lipophagy. Mech Ageing Dev 2024; 219:111933. [PMID: 38588730 DOI: 10.1016/j.mad.2024.111933] [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: 09/22/2023] [Revised: 03/31/2024] [Accepted: 04/02/2024] [Indexed: 04/10/2024]
Abstract
The global prevalence of nonalcoholic fatty liver disease (NAFLD) defined by the increased number of lipid droplets (LDs) in hepatocytes, have risen continuously in parallel with the obesity. LDs and related proteins are known to affect cellular metabolism and signaling. Seipin, one of the most important LD-related proteins, plays a critical role in LD biogenesis. Although the role of adipose tissue-specific Seipin silencing is known, hepatocyte-specific silencing upon cholesterol-mediated lipid accumulation has not been investigated. In our study, we investigated the effect of Seipin on endoplasmic reticulum (ER) stress and lipophagy in cholesterol accumulated mouse hepatocyte cells. In this direction, cholesterol accumulation was induced by cholesterol-containing liposome, while Seipin mRNA and protein levels were reduced by siRNA. Our findings show that cholesterol containing liposome administration in hepatocytes increases both Seipin protein and number of large LDs. However Seipin silencing reduced the increase of cholesterol mediated large LDs and Glucose-regulated protein 78 (GRP78) mRNA. Additionally, lysosome-LD colocalization increased only in cells treated with cholesterol containing liposome, while the siRNA against Seipin did not lead any significant difference. According to our findings, we hypothesize that Seipin silencing in hepatocytes reduced cholesterol mediated LD maturation as well as GRP78 levels, but not lipophagy.
Collapse
Affiliation(s)
- Tugce Demirel-Yalciner
- Department of Biochemistry, Faculty of Medicine, Uskudar University, Istanbul 34662, Turkey; Department of Biochemistry, Faculty of Medicine, Marmara University, Maltepe, Istanbul 34854, Turkey; Metabolic and Inflammatory Diseases Research Center (METIFLAM), Uskudar University, Istanbul 34662, Turkey
| | - Bengu Cetinkaya
- Department of Biochemistry, Faculty of Medicine, Marmara University, Maltepe, Istanbul 34854, Turkey
| | - Erdi Sozen
- Department of Biochemistry, Faculty of Medicine, Marmara University, Maltepe, Istanbul 34854, Turkey; Genetic and Metabolic Diseases Research Center (GEMHAM), Marmara University, Maltepe, Istanbul 34854, Turkey
| | - Nesrin Kartal Ozer
- Department of Biochemistry, Faculty of Medicine, Uskudar University, Istanbul 34662, Turkey; Metabolic and Inflammatory Diseases Research Center (METIFLAM), Uskudar University, Istanbul 34662, Turkey.
| |
Collapse
|
12
|
Dhiman R, Perera RS, Poojari CS, Wiedemann HTA, Kappl R, Kay CWM, Hub JS, Schrul B. Hairpin protein partitioning from the ER to lipid droplets involves major structural rearrangements. Nat Commun 2024; 15:4504. [PMID: 38802378 PMCID: PMC11130287 DOI: 10.1038/s41467-024-48843-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 05/15/2024] [Indexed: 05/29/2024] Open
Abstract
Lipid droplet (LD) function relies on proteins partitioning between the endoplasmic reticulum (ER) phospholipid bilayer and the LD monolayer membrane to control cellular adaptation to metabolic changes. It has been proposed that these hairpin proteins integrate into both membranes in a similar monotopic topology, enabling their passive lateral diffusion during LD emergence at the ER. Here, we combine biochemical solvent-accessibility assays, electron paramagnetic resonance spectroscopy and intra-molecular crosslinking experiments with molecular dynamics simulations, and determine distinct intramembrane positionings of the ER/LD protein UBXD8 in ER bilayer and LD monolayer membranes. UBXD8 is deeply inserted into the ER bilayer with a V-shaped topology and adopts an open-shallow conformation in the LD monolayer. Major structural rearrangements are required to enable ER-to-LD partitioning. Free energy calculations suggest that such structural transition is unlikely spontaneous, indicating that ER-to-LD protein partitioning relies on more complex mechanisms than anticipated and providing regulatory means for this trans-organelle protein trafficking.
Collapse
Affiliation(s)
- Ravi Dhiman
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421, Homburg/Saar, Germany
| | - Rehani S Perera
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421, Homburg/Saar, Germany
| | - Chetan S Poojari
- Theoretical Physics and Center for Biophysics, Saarland University, 66123, Saarbrücken, Germany
| | - Haakon T A Wiedemann
- Physical Chemistry and Chemistry Education, Saarland University, 66123, Saarbrücken, Germany
| | - Reinhard Kappl
- Department of Biophysics, Center for Integrative Physiology and Molecular Medicine (CIPMM), Faculty of Medicine, Saarland University, 66421, Homburg/Saar, Germany
| | - Christopher W M Kay
- Physical Chemistry and Chemistry Education, Saarland University, 66123, Saarbrücken, Germany
- London Centre for Nanotechnology, University College London, WC1H 0AH, London, UK
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University, 66123, Saarbrücken, Germany
| | - Bianca Schrul
- Medical Biochemistry and Molecular Biology, Center for Molecular Signaling (PZMS), Faculty of Medicine, Saarland University, 66421, Homburg/Saar, Germany.
| |
Collapse
|
13
|
Gandhi SA, Parveen S, Alduhailan M, Tripathi R, Junedi N, Saqallah M, Sanders MA, Hoffmann PM, Truex K, Granneman JG, Kelly CV. Methods for making and observing model lipid droplets. CELL REPORTS METHODS 2024; 4:100774. [PMID: 38749444 PMCID: PMC11133809 DOI: 10.1016/j.crmeth.2024.100774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/30/2024] [Accepted: 04/19/2024] [Indexed: 05/23/2024]
Abstract
We present methods for making and testing the membrane biophysics of model lipid droplets (LDs). Methods are described for imaging LDs ranging in size from 0.1 to 40 μm in diameter with high-resolution microscopy and spectroscopy. With known LD compositions, membrane binding, sorting, diffusion, and tension were measured via fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), fluorescence lifetime imaging microscopy (FLIM), atomic force microscopy (AFM), and imaging flow cytometry. Additionally, a custom, small-volume pendant droplet tensiometer is described and used to measure the association of phospholipids to the LD surface. These complementary, cross-validating methods of measuring LD membrane behavior reveal the interplay of biophysical processes on lipid droplet monolayers.
Collapse
Affiliation(s)
- Sonali A Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Shahnaz Parveen
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Munirah Alduhailan
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Ramesh Tripathi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Nasser Junedi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Mohammad Saqallah
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Matthew A Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Peter M Hoffmann
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA; Physical Sciences Department, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, USA
| | - Katherine Truex
- Department of Physics, United States Naval Academy, Annapolis, MD 21402, USA
| | - James G Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA.
| |
Collapse
|
14
|
Santinho A, Carpentier M, Lopes Sampaio J, Omrane M, Thiam AR. Giant organelle vesicles to uncover intracellular membrane mechanics and plasticity. Nat Commun 2024; 15:3767. [PMID: 38704407 PMCID: PMC11069511 DOI: 10.1038/s41467-024-48086-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 04/22/2024] [Indexed: 05/06/2024] Open
Abstract
Tools for accessing and studying organelles remain underdeveloped. Here, we present a method by which giant organelle vesicles (GOVs) are generated by submitting cells to a hypotonic medium followed by plasma membrane breakage. By this means, GOVs ranging from 3 to over 10 µm become available for micromanipulation. GOVs are made from organelles such as the endoplasmic reticulum, endosomes, lysosomes and mitochondria, or in contact with one another such as giant mitochondria-associated ER membrane vesicles. We measure the mechanical properties of each organelle-derived GOV and find that they have distinct properties. In GOVs procured from Cos7 cells, for example, bending rigidities tend to increase from the endoplasmic reticulum to the plasma membrane. We also found that the mechanical properties of giant endoplasmic reticulum vesicles (GERVs) vary depending on their interactions with other organelles or the metabolic state of the cell. Lastly, we demonstrate GERVs' biochemical activity through their capacity to synthesize triglycerides and assemble lipid droplets. These findings underscore the potential of GOVs as valuable tools for studying the biophysics and biology of organelles.
Collapse
Affiliation(s)
- Alexandre Santinho
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - Maxime Carpentier
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - Julio Lopes Sampaio
- Institut Curie, PSL Research University, Plateforme de Métabolomique et Lipidomique, 26 rue d'Ulm, Paris, France
| | - Mohyeddine Omrane
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, F-75005, Paris, France.
| |
Collapse
|
15
|
Xu L, Li L, Wu L, Li P, Chen FJ. CIDE proteins and their regulatory mechanisms in lipid droplet fusion and growth. FEBS Lett 2024; 598:1154-1169. [PMID: 38355218 DOI: 10.1002/1873-3468.14823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 12/19/2023] [Accepted: 01/04/2024] [Indexed: 02/16/2024]
Abstract
The cell death-inducing DFF45-like effector (CIDE) proteins, including Cidea, Cideb, and Cidec/Fsp27, regulate various aspects of lipid homeostasis, including lipid storage, lipolysis, and lipid secretion. This review focuses on the physiological roles of CIDE proteins based on studies on knockout mouse models and human patients bearing CIDE mutations. The primary cellular function of CIDE proteins is to localize to lipid droplets (LDs) and to control LD fusion and growth across different cell types. We propose a four-step process of LD fusion, characterized by (a) the recruitment of CIDE proteins to the LD surface and CIDE movement, (b) the enrichment and condensate formation of CIDE proteins to form LD fusion plates at LD-LD contact sites, (c) lipid transfer through lipid-permeable passageways within the fusion plates, and (d) the completion of LD fusion. Lastly, we outline CIDE-interacting proteins as regulatory factors, as well as their contribution in LD fusion.
Collapse
Affiliation(s)
- Li Xu
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lizhen Li
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lingzhi Wu
- College of Future Technology, Peking University, Beijing, China
| | - Peng Li
- State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China
- Tianjian Laboratory of Advanced Biomedical Sciences, Zhengzhou University, China
| | - Feng-Jung Chen
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Institute of Metabolism and Integrative Biology, Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China
| |
Collapse
|
16
|
Sapia J, Vanni S. Molecular dynamics simulations of intracellular lipid droplets: a new tool in the toolbox. FEBS Lett 2024; 598:1143-1153. [PMID: 38627196 DOI: 10.1002/1873-3468.14879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/14/2024] [Accepted: 03/25/2024] [Indexed: 05/25/2024]
Abstract
Lipid droplets (LDs) are ubiquitous intracellular organelles with a central role in multiple lipid metabolic pathways. However, identifying correlations between their structural properties and their biological activity has proved challenging, owing to their unique physicochemical properties as compared with other cellular membranes. In recent years, molecular dynamics (MD) simulations, a computational methodology allowing the accurate description of molecular assemblies down to their individual components, have been demonstrated to be a useful and powerful approach for studying LD structural and dynamical properties. In this short review, we attempt to highlight, as comprehensively as possible, how MD simulations have contributed to our current understanding of multiple molecular mechanisms involved in LD biology.
Collapse
Affiliation(s)
- Jennifer Sapia
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Stefano Vanni
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France
- Swiss National Center for Competence in Research (NCCR) Bio-inspired Materials, University of Fribourg, Fribourg, Switzerland
| |
Collapse
|
17
|
Klug YA, Ferreira JV, Carvalho P. A unifying mechanism for seipin-mediated lipid droplet formation. FEBS Lett 2024; 598:1116-1126. [PMID: 38785192 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.
Collapse
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
| |
Collapse
|
18
|
Monteiro-Cardoso VF, Giordano F. Emerging functions of the mitochondria-ER-lipid droplet three-way junction in coordinating lipid transfer, metabolism, and storage in cells. FEBS Lett 2024; 598:1252-1273. [PMID: 38774950 DOI: 10.1002/1873-3468.14893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 03/18/2024] [Accepted: 04/05/2024] [Indexed: 05/25/2024]
Abstract
Over the past two decades, we have witnessed a growing appreciation for the importance of membrane contact sites (CS) in facilitating direct communication between organelles. CS are tiny regions where the membranes of two organelles meet but do not fuse and allow the transfer of metabolites between organelles, playing crucial roles in the coordination of cellular metabolic activities. The significant advancements in imaging techniques and molecular and cell biology research have revealed that CS are more complex than what originally thought, and as they are extremely dynamic, they can remodel their shape, composition, and functions in accordance with metabolic and environmental changes and can occur between more than two organelles. Here, we describe how recent studies led to the identification of a three-way mitochondria-ER-lipid droplet CS and discuss the emerging functions of these contacts in maintaining lipid storage, homeostasis, and balance. We also summarize the properties and functions of key protein components localized at the mitochondria-ER-lipid droplet interface, with a special focus on lipid transfer proteins. Understanding tripartite CS is essential for unraveling the complexities of inter-organelle communication and cooperation within cells.
Collapse
Affiliation(s)
- Vera Filipa Monteiro-Cardoso
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette cedex, France
- Inserm U1280, Gif-sur-Yvette cedex, France
| | - Francesca Giordano
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette cedex, France
- Inserm U1280, Gif-sur-Yvette cedex, France
| |
Collapse
|
19
|
Dudka W, Salo VT, Mahamid J. Zooming into lipid droplet biology through the lens of electron microscopy. FEBS Lett 2024; 598:1127-1142. [PMID: 38726814 DOI: 10.1002/1873-3468.14899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Revised: 04/08/2024] [Accepted: 04/24/2024] [Indexed: 05/25/2024]
Abstract
Electron microscopy (EM), in its various flavors, has significantly contributed to our understanding of lipid droplets (LD) as central organelles in cellular metabolism. For example, EM has illuminated that LDs, in contrast to all other cellular organelles, are uniquely enclosed by a single phospholipid monolayer, revealed the architecture of LD contact sites with different organelles, and provided near-atomic resolution maps of key enzymes that regulate neutral lipid biosynthesis and LD biogenesis. In this review, we first provide a brief history of pivotal findings in LD biology unveiled through the lens of an electron microscope. We describe the main EM techniques used in the context of LD research and discuss their current capabilities and limitations, thereby providing a foundation for utilizing suitable EM methodology to address LD-related questions with sufficient level of structural preservation, detail, and resolution. Finally, we highlight examples where EM has recently been and is expected to be instrumental in expanding the frontiers of LD biology.
Collapse
Affiliation(s)
- Wioleta Dudka
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Veijo T Salo
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- Cell Biology and Biophysics Unit, EMBL, Heidelberg, Germany
| |
Collapse
|
20
|
Diep DTV, Collado J, Hugenroth M, Fausten RM, Percifull L, Wälte M, Schuberth C, Schmidt O, Fernández-Busnadiego R, Bohnert M. A metabolically controlled contact site between vacuoles and lipid droplets in yeast. Dev Cell 2024; 59:740-758.e10. [PMID: 38367622 DOI: 10.1016/j.devcel.2024.01.016] [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: 04/26/2023] [Revised: 11/17/2023] [Accepted: 01/18/2024] [Indexed: 02/19/2024]
Abstract
The lipid droplet (LD) organization proteins Ldo16 and Ldo45 affect multiple aspects of LD biology in yeast. They are linked to the LD biogenesis machinery seipin, and their loss causes defects in LD positioning, protein targeting, and breakdown. However, their molecular roles remained enigmatic. Here, we report that Ldo16/45 form a tether complex with Vac8 to create vacuole lipid droplet (vCLIP) contact sites, which can form in the absence of seipin. The phosphatidylinositol transfer protein (PITP) Pdr16 is a further vCLIP-resident recruited specifically by Ldo45. While only an LD subpopulation is engaged in vCLIPs at glucose-replete conditions, nutrient deprivation results in vCLIP expansion, and vCLIP defects impair lipophagy upon prolonged starvation. In summary, Ldo16/45 are multifunctional proteins that control the formation of a metabolically regulated contact site. Our studies suggest a link between LD biogenesis and breakdown and contribute to a deeper understanding of how lipid homeostasis is maintained during metabolic challenges.
Collapse
Affiliation(s)
- Duy Trong Vien Diep
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Javier Collado
- Institute of Neuropathology, University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Marie Hugenroth
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Rebecca Martina Fausten
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Louis Percifull
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Mike Wälte
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany
| | - Christian Schuberth
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany
| | - Oliver Schmidt
- Institute of Cell Biology, Biocenter Innsbruck, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Rubén Fernández-Busnadiego
- Institute of Neuropathology, University Medical Center Göttingen, 37099 Göttingen, Germany; Cluster of Excellence "Multiscale Imaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany; Faculty of Physics, University of Göttingen, Göttingen 37077, Germany
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Strasse 56, 48149 Münster, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, Germany.
| |
Collapse
|
21
|
Mathiowetz AJ, Olzmann JA. Lipid droplets and cellular lipid flux. Nat Cell Biol 2024; 26:331-345. [PMID: 38454048 PMCID: PMC11228001 DOI: 10.1038/s41556-024-01364-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 01/24/2024] [Indexed: 03/09/2024]
Abstract
Lipid droplets are dynamic organelles that store neutral lipids, serve the metabolic needs of cells, and sequester lipids to prevent lipotoxicity and membrane damage. Here we review the current understanding of the mechanisms of lipid droplet biogenesis and turnover, the transfer of lipids and metabolites at membrane contact sites, and the role of lipid droplets in regulating fatty acid flux in lipotoxicity and cell death.
Collapse
Affiliation(s)
- Alyssa J Mathiowetz
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA, USA
| | - James A Olzmann
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
- Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, CA, USA.
- Chan Zuckerberg Biohub - San Francisco, San Francisco, CA, USA.
| |
Collapse
|
22
|
Li S, Wang Y, van der Stoel M, Zhou X, Madhusudan S, Kanerva K, Nguyen VD, Eskici N, Olkkonen VM, Zhou Y, Raivio T, Ikonen E. HiHo-AID2: boosting homozygous knock-in efficiency enables robust generation of human auxin-inducible degron cells. Genome Biol 2024; 25:58. [PMID: 38409044 PMCID: PMC10895734 DOI: 10.1186/s13059-024-03187-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 02/14/2024] [Indexed: 02/28/2024] Open
Abstract
Recent developments in auxin-inducible degron (AID) technology have increased its popularity for chemogenetic control of proteolysis. However, generation of human AID cell lines is challenging, especially in human embryonic stem cells (hESCs). Here, we develop HiHo-AID2, a streamlined procedure for rapid, one-step generation of human cancer and hESC lines with high homozygous degron-tagging efficiency based on an optimized AID2 system and homology-directed repair enhancers. We demonstrate its application for rapid and inducible functional inactivation of twelve endogenous target proteins in five cell lines, including targets with diverse expression levels and functions in hESCs and cells differentiated from hESCs.
Collapse
Affiliation(s)
- Shiqian Li
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland.
- Minerva Foundation Institute for Medical Research, 00290, Helsinki, Finland.
| | - Yafei Wang
- Stem Cells and Metabolism Research Program, Research Programs Unit, and Department of Physiology, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
| | - Miesje van der Stoel
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, 00290, Helsinki, Finland
| | - Xin Zhou
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, 00290, Helsinki, Finland
| | - Shrinidhi Madhusudan
- Stem Cells and Metabolism Research Program, Research Programs Unit, and Department of Physiology, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
| | - Kristiina Kanerva
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, 00290, Helsinki, Finland
| | - Van Dien Nguyen
- Systems Immunity Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
- Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, CF14 4XN, UK
| | - Nazli Eskici
- Stem Cells and Metabolism Research Program, Research Programs Unit, and Department of Physiology, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
| | - Vesa M Olkkonen
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
- Minerva Foundation Institute for Medical Research, 00290, Helsinki, Finland
| | - You Zhou
- Systems Immunity Research Institute, Cardiff University, Cardiff, CF14 4XN, UK
- Division of Infection and Immunity, School of Medicine, Cardiff University, Cardiff, CF14 4XN, UK
| | - Taneli Raivio
- Stem Cells and Metabolism Research Program, Research Programs Unit, and Department of Physiology, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
- New Children's Hospital, Pediatric Research Center, Helsinki University Hospital, 00290, Helsinki, Finland
| | - Elina Ikonen
- Department of Anatomy and Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland.
- Minerva Foundation Institute for Medical Research, 00290, Helsinki, Finland.
| |
Collapse
|
23
|
Sun S, Zhao G, Jia M, Jiang Q, Li S, Wang H, Li W, Wang Y, Bian X, Zhao YG, Huang X, Yang G, Cai H, Pastor-Pareja JC, Ge L, Zhang C, Hu J. Stay in touch with the endoplasmic reticulum. SCIENCE CHINA. LIFE SCIENCES 2024; 67:230-257. [PMID: 38212460 DOI: 10.1007/s11427-023-2443-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 08/28/2023] [Indexed: 01/13/2024]
Abstract
The endoplasmic reticulum (ER), which is composed of a continuous network of tubules and sheets, forms the most widely distributed membrane system in eukaryotic cells. As a result, it engages a variety of organelles by establishing membrane contact sites (MCSs). These contacts regulate organelle positioning and remodeling, including fusion and fission, facilitate precise lipid exchange, and couple vital signaling events. Here, we systematically review recent advances and converging themes on ER-involved organellar contact. The molecular basis, cellular influence, and potential physiological functions for ER/nuclear envelope contacts with mitochondria, Golgi, endosomes, lysosomes, lipid droplets, autophagosomes, and plasma membrane are summarized.
Collapse
Affiliation(s)
- Sha Sun
- National Laboratory of Biomacromolecules, Institute of Biophysics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100101, China
| | - Gan Zhao
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Mingkang Jia
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Qing Jiang
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, 100871, China
| | - Shulin Li
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Haibin Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100101, China
| | - Wenjing Li
- Laboratory of Computational Biology & Machine Intelligence, School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yunyun Wang
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Xin Bian
- State Key Laboratory of Medicinal Chemical Biology, College of Life Sciences, Nankai University, Tianjin, 300071, China.
| | - Yan G Zhao
- Brain Research Center, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Xun Huang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Ge Yang
- Laboratory of Computational Biology & Machine Intelligence, School of Artificial Intelligence, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Huaqing Cai
- National Laboratory of Biomacromolecules, Institute of Biophysics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Jose C Pastor-Pareja
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Institute of Neurosciences, Consejo Superior de Investigaciones Cientfflcas-Universidad Miguel Hernandez, San Juan de Alicante, 03550, Spain.
| | - Liang Ge
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| | - Chuanmao Zhang
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, 100871, China.
| | - Junjie Hu
- National Laboratory of Biomacromolecules, Institute of Biophysics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100101, China.
| |
Collapse
|
24
|
Kazemisabet F, Bahrami A, Ghosh R, Różycki B, Bahrami AH. Molecular mechanisms and energetics of lipid droplet formation and directional budding. SOFT MATTER 2024; 20:909-922. [PMID: 38189157 DOI: 10.1039/d3sm01438j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
The formation and budding of lipid droplets (LDs) are known to be governed by the LD size and by membrane tensions in the endoplasmic reticulum (ER) bilayer and LD-monolayers. Using coarse-grained simulations of an LD model, we first show that ER-embedded LDs of different sizes can form through a continuous transition from wide LD lenses to spherical LDs at a fixed LD size. The ER tendency to relax its bilayer modulates the transition via a subtle interplay between the ER and LD lipid densities. By calculating the energetic landscape of the LD transition, we demonstrate that this size-independent transition is regulated by the mechanical force balance of ER and LD-tensions, independent from membrane bending and line tension whose energetic contributions are negligible according to our calculations. Our findings explain experimental observation of stable LDs of various shapes. We then propose a novel mechanism for directional LD budding where the required membrane asymmetry is provided by the exchange of lipids between the LD-monolayers. Remarkably, we demonstrate that this budding process is energetically neutral. Consequently, LD budding can proceed by a modest energy input from proteins or other driving agents. We obtain equal lipid densities and membrane tensions in LD-monolayers throughout budding. Our findings indicate that unlike LD formation, LD budding by inter-monolayer lipid exchange is a tension-independent process.
Collapse
Affiliation(s)
- Fatemeh Kazemisabet
- School of Mechanical Engineering, College of Engineering, University of Tehran, North Kargar St., 14399-57131 Tehran, Iran
| | - Arash Bahrami
- School of Mechanical Engineering, College of Engineering, University of Tehran, North Kargar St., 14399-57131 Tehran, Iran
| | - Rikhia Ghosh
- Department of Pharmacological Sciences, Icahn School of Medicine, Mount Sinai, New York 10029, USA
| | - Bartosz Różycki
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Amir H Bahrami
- UNAM-National Nanotechnology Research Center and Institute of Materials Science & Nanotechnology, Bilkent University, Ankara, Turkey.
- Living Matter Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| |
Collapse
|
25
|
Voeltz GK, Sawyer EM, Hajnóczky G, Prinz WA. Making the connection: How membrane contact sites have changed our view of organelle biology. Cell 2024; 187:257-270. [PMID: 38242082 DOI: 10.1016/j.cell.2023.11.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/13/2023] [Accepted: 11/29/2023] [Indexed: 01/21/2024]
Abstract
The view of organelles and how they operate together has changed dramatically over the last two decades. The textbook view of organelles was that they operated largely independently and were connected by vesicular trafficking and the diffusion of signals through the cytoplasm. We now know that all organelles make functional close contacts with one another, often called membrane contact sites. The study of these sites has moved to center stage in cell biology as it has become clear that they play critical roles in healthy and developing cells and during cell stress and disease states. Contact sites have important roles in intracellular signaling, lipid metabolism, motor-protein-mediated membrane dynamics, organelle division, and organelle biogenesis. Here, we summarize the major conceptual changes that have occurred in cell biology as we have come to appreciate how contact sites integrate the activities of organelles.
Collapse
Affiliation(s)
- G K Voeltz
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
| | - E M Sawyer
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, CO 80309, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - G Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - W A Prinz
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
| |
Collapse
|
26
|
Makiyama T, Obama T, Watanabe Y, Chatani M, Azetsu Y, Kawaguchi K, Imanaka T, Itabe H. Behavior of intracellular lipid droplets during cell division in HuH7 hepatoma cells. Exp Cell Res 2023; 433:113855. [PMID: 37995922 DOI: 10.1016/j.yexcr.2023.113855] [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: 06/23/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 11/25/2023]
Abstract
Intracellular lipid droplets (LDs) are ubiquitous organelles found in many cell types. During mitosis, membranous organelles, including mitochondria, are divided into small pieces and transferred to daughter cells; however, the process of LD transfer to daughter cells is not fully elucidated. Herein, we investigated the behavior of LDs during mitosis in HuH7 human hepatoma cells. While fragments of the Golgi apparatus were scattered in the cytosol during mitosis, intracellular LDs retained their size and spherical morphology as they translocated to the two daughter cells. LDs were initially distributed throughout the cell during prophase but positioned outside the spindle in metaphase, aligning at the far sides of the centrioles. A similar distribution of LDs during mitosis was observed in another hepatocarcinoma HepG2 cells. When the spindle was disrupted by nocodazole treatment or never in mitosis gene A-related kinase 2A knockdown, LDs were localized in the area outside the chromosomes, suggesting that spindle formation is not necessary for LD localization at metaphase. The amount of major LD protein perilipin 2 reduced while LDs were enriched in perilipin 3 during mitosis, indicating the potential alteration of LD protein composition. Conclusively, the behavior of LDs during mitosis is distinct from that of other organelles in hepatocytes.
Collapse
Affiliation(s)
- Tomohiko Makiyama
- Department of Biological Chemistry, Showa University Graduate School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.
| | - Takashi Obama
- Department of Biological Chemistry, Showa University Graduate School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Yuichi Watanabe
- Department of Biological Chemistry, Showa University Graduate School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Masahiro Chatani
- Department of Pharmacology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan; Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Yuki Azetsu
- Department of Pharmacology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan; Pharmacological Research Center, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Kosuke Kawaguchi
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan
| | - Tsuneo Imanaka
- Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama, 930-0194, Japan; Faculty of Pharmaceutical Sciences, Hiroshima International University, 5-1-1 Hirokoshinkai, Kure City, Hiroshima, 737-0112, Japan
| | - Hiroyuki Itabe
- Department of Biological Chemistry, Showa University Graduate School of Pharmacy, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| |
Collapse
|
27
|
López-Alcalá J, Soler-Vázquez MC, Tercero-Alcázar C, Sánchez-Ceinos J, Guzmán-Ruiz R, Malagón MM, Gordon A. Rab18 Drift in Lipid Droplet and Endoplasmic Reticulum Interactions of Adipocytes under Obesogenic Conditions. Int J Mol Sci 2023; 24:17177. [PMID: 38139006 PMCID: PMC10743551 DOI: 10.3390/ijms242417177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023] Open
Abstract
The adipose tissue stores excess energy in the form of neutral lipids within adipocyte lipid droplets (LDs). The correct function of LDs requires the interaction with other organelles, such as the endoplasmic reticulum (ER) as well as with LD coat-associated proteins, including Rab18, a mediator of intracellular lipid trafficking and ER-LD interaction. Although perturbations of the inter-organelle contact sites have been linked to several diseases, such as cancer, no information regarding ER-LD contact sites in dysfunctional adipocytes from the obese adipose tissue has been published to date. Herein, the ER-LD connection and Rab18 distribution at ER-LD contact sites are examined in adipocytes challenged with fibrosis and inflammatory conditions, which represent known hallmarks of the adipose tissue in obesity. Our results show that adipocytes differentiated in fibrotic conditions caused ER fragmentation, the expansion of ER-LD contact sites, and modified Rab18 dynamics. Likewise, adipocytes exposed to inflammatory conditions favored ER-LD contact, Rab18 accumulation in the ER, and Rab18 redistribution to large LDs. Finally, our studies in human adipocytes supported the suggestion that Rab18 transitions to the LD coat from the ER. Taken together, our results suggest that obesity-related pathogenic processes alter the maintenance of ER-LD interactions and interfere with Rab18 trafficking through these contact sites.
Collapse
Affiliation(s)
- Jaime López-Alcalá
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
| | - M. Carmen Soler-Vázquez
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
- Department of Biochemistry and Physiology, School of Pharmacy and Food Sciences, Instituto de Biomedicina de la Universitat de Barcelona (IBUB), Universitat de Barcelona, 08028 Barcelona, Spain
| | - Carmen Tercero-Alcázar
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
| | - Julia Sánchez-Ceinos
- Cardiology Unit, Department of Medicine-Solna, Karolinska Institute (KI), Karolinska University Hospital (NKS), 17177 Stockholm, Sweden;
| | - Rocío Guzmán-Ruiz
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - María M. Malagón
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Ana Gordon
- Department of Cell Biology, Physiology, and Immunology, Adipobiology Group, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofia University Hospital, University of Córdoba, 14004 Córdoba, Spain; (J.L.-A.); (M.C.S.-V.); (C.T.-A.); (R.G.-R.)
| |
Collapse
|
28
|
Fung HKH, Hayashi Y, Salo VT, Babenko A, Zagoriy I, Brunner A, Ellenberg J, Müller CW, Cuylen-Haering S, Mahamid J. Genetically encoded multimeric tags for subcellular protein localization in cryo-EM. Nat Methods 2023; 20:1900-1908. [PMID: 37932397 PMCID: PMC10703698 DOI: 10.1038/s41592-023-02053-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Accepted: 09/19/2023] [Indexed: 11/08/2023]
Abstract
Cryo-electron tomography (cryo-ET) allows for label-free high-resolution imaging of macromolecular assemblies in their native cellular context. However, the localization of macromolecules of interest in tomographic volumes can be challenging. Here we present a ligand-inducible labeling strategy for intracellular proteins based on fluorescent, 25-nm-sized, genetically encoded multimeric particles (GEMs). The particles exhibit recognizable structural signatures, enabling their automated detection in cryo-ET data by convolutional neural networks. The coupling of GEMs to green fluorescent protein-tagged macromolecules of interest is triggered by addition of a small-molecule ligand, allowing for time-controlled labeling to minimize disturbance to native protein function. We demonstrate the applicability of GEMs for subcellular-level localization of endogenous and overexpressed proteins across different organelles in human cells using cryo-correlative fluorescence and cryo-ET imaging. We describe means for quantifying labeling specificity and efficiency, and for systematic optimization for rare and abundant protein targets, with emphasis on assessing the potential effects of labeling on protein function.
Collapse
Affiliation(s)
- Herman K H Fung
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Yuki Hayashi
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Veijo T Salo
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Anastasiia Babenko
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
- University of Heidelberg, Heidelberg, Germany
| | - Ievgeniia Zagoriy
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Andreas Brunner
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
- Faculty of Biosciences, Collaboration for Joint PhD Degree between EMBL and Heidelberg University, Heidelberg, Germany
| | - Jan Ellenberg
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Christoph W Müller
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Sara Cuylen-Haering
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany.
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany.
| |
Collapse
|
29
|
Kumari RM, Khatri A, Chaudhary R, Choudhary V. Concept of lipid droplet biogenesis. Eur J Cell Biol 2023; 102:151362. [PMID: 37742390 PMCID: PMC7615795 DOI: 10.1016/j.ejcb.2023.151362] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/26/2023] Open
Abstract
Lipid droplets (LD) are functionally conserved fat storage organelles found in all cell types. LDs have a unique structure comprising of a hydrophobic core of neutral lipids (fat), triacylglycerol (TAG) and cholesterol esters (CE) surrounded by a phospholipid monolayer. LD surface is decorated by a multitude of proteins and enzymes rendering this compartment functional. Accumulating evidence suggests that LDs originate from discrete ER-subdomains, demarcated by the lipodystrophy protein seipin, however, the mechanisms of which are not well understood. LD biogenesis factors together with biophysical properties of the ER membrane orchestrate spatiotemporal regulation of LD nucleation and growth at specific ER subdomains in response to metabolic cues. Defects in LD formation manifests in several human pathologies, including obesity, lipodystrophy, ectopic fat accumulation, and insulin resistance. Here, we review recent advances in understanding the molecular events during initial stages of eukaryotic LD assembly and discuss the critical role of factors that ensure fidelity of this process.
Collapse
Affiliation(s)
- R Mankamna Kumari
- Lipid Metabolism Laboratory, Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Amit Khatri
- Lipid Metabolism Laboratory, Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Ritika Chaudhary
- Lipid Metabolism Laboratory, Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India
| | - Vineet Choudhary
- Lipid Metabolism Laboratory, Department of Biotechnology, All India Institute of Medical Sciences (AIIMS), New Delhi 110029, India.
| |
Collapse
|
30
|
Li X, Gamuyao R, Wu ML, Cho WJ, Kurtz NB, King SV, Petersen R, Stabley DR, Lindow C, Climer L, Shirinifard A, Ferrara F, Throm RE, Robinson CG, Carisey A, Tebo AG, Chang CL. A fluorogenic complementation tool kit for interrogating lipid droplet-organelle interaction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.29.569289. [PMID: 38076863 PMCID: PMC10705429 DOI: 10.1101/2023.11.29.569289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Contact sites between lipid droplets and other organelles are essential for cellular lipid and energy homeostasis. Detection of these contact sites at nanometer scale over time in living cells is challenging. Here, we developed a tool kit for detecting contact sites based on Fluorogen-Activated Bimolecular complementation at CONtact sites, FABCON, using a reversible, low affinity split fluorescent protein, splitFAST. FABCON labels contact sites with minimal perturbation to organelle interaction. Via FABCON, we quantitatively demonstrated that endoplasmic reticulum (ER)- and mitochondria (mito)-lipid droplet contact sites are dynamic foci in distinct metabolic conditions, such as during lipid droplet biogenesis and consumption. An automated analysis pipeline further classified individual contact sites into distinct subgroups based on size, likely reflecting differential regulation and function. Moreover, FABCON is generalizable to visualize a repertoire of organelle contact sites including ER-mito. Altogether, FABCON reveals insights into the dynamic regulation of lipid droplet-organelle contact sites and generates new hypotheses for further mechanistical interrogation during metabolic switch.
Collapse
Affiliation(s)
- Xiao Li
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Rico Gamuyao
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Ming-Lun Wu
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Woo Jung Cho
- Cell and Tissue Imaging Center, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Nathan B. Kurtz
- Cell and Tissue Imaging Center, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Sharon V. King
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - R.A. Petersen
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Daniel R. Stabley
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Caleb Lindow
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Leslie Climer
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Abbas Shirinifard
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Francesca Ferrara
- Vector Production and Development Laboratory, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Robert E. Throm
- Vector Production and Development Laboratory, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Camenzind G. Robinson
- Cell and Tissue Imaging Center, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Alex Carisey
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Alison G. Tebo
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Chi-Lun Chang
- Department of Cell and Molecular Biology, St. Jude Children’s Research Hospital, Memphis, TN, United States
| |
Collapse
|
31
|
Kiss RS, Chicoine J, Khalil Y, Sladek R, Chen H, Pisaturo A, Martin C, Dale JD, Brudenell TA, Kamath A, Kyei-Boahen J, Hafiane A, Daliah G, Alecki C, Hopes TS, Heier M, Aligianis IA, Lebrun JJ, Aspden J, Paci E, Kerksiek A, Lütjohann D, Clayton P, Wills JC, von Kriegsheim A, Nilsson T, Sheridan E, Handley MT. Comparative proximity biotinylation implicates the small GTPase RAB18 in sterol mobilization and biosynthesis. J Biol Chem 2023; 299:105295. [PMID: 37774976 PMCID: PMC10641524 DOI: 10.1016/j.jbc.2023.105295] [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: 03/16/2023] [Revised: 09/14/2023] [Accepted: 09/17/2023] [Indexed: 10/01/2023] Open
Abstract
Loss of functional RAB18 causes the autosomal recessive condition Warburg Micro syndrome. To better understand this disease, we used proximity biotinylation to generate an inventory of potential RAB18 effectors. A restricted set of 28 RAB18 interactions were dependent on the binary RAB3GAP1-RAB3GAP2 RAB18-guanine nucleotide exchange factor complex. Twelve of these 28 interactions are supported by prior reports, and we have directly validated novel interactions with SEC22A, TMCO4, and INPP5B. Consistent with a role for RAB18 in regulating membrane contact sites, interactors included groups of microtubule/membrane-remodeling proteins, membrane-tethering and docking proteins, and lipid-modifying/transporting proteins. Two of the putative interactors, EBP and OSBPL2/ORP2, have sterol substrates. EBP is a Δ8-Δ7 sterol isomerase, and ORP2 is a lipid transport protein. This prompted us to investigate a role for RAB18 in cholesterol biosynthesis. We found that the cholesterol precursor and EBP-product lathosterol accumulates in both RAB18-null HeLa cells and RAB3GAP1-null fibroblasts derived from an affected individual. Furthermore, de novo cholesterol biosynthesis is impaired in cells in which RAB18 is absent or dysregulated or in which ORP2 expression is disrupted. Our data demonstrate that guanine nucleotide exchange factor-dependent Rab interactions are highly amenable to interrogation by proximity biotinylation and may suggest that Micro syndrome is a cholesterol biosynthesis disorder.
Collapse
Affiliation(s)
- Robert S Kiss
- Cardiovascular Health Across the Lifespan (CHAL) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.
| | - Jarred Chicoine
- Metabolic Disorders and Complications (MEDIC) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Youssef Khalil
- Genetics and Genomic Medicine, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Robert Sladek
- Metabolic Disorders and Complications (MEDIC) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - He Chen
- Cardiovascular Health Across the Lifespan (CHAL) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Alessandro Pisaturo
- Cardiovascular Health Across the Lifespan (CHAL) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Cyril Martin
- Cardiovascular Health Across the Lifespan (CHAL) Program, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Jessica D Dale
- Leeds Institute of Medical Research, St James's University Hospital, Leeds, United Kingdom
| | - Tegan A Brudenell
- Leeds Institute of Medical Research, St James's University Hospital, Leeds, United Kingdom
| | - Archith Kamath
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom; Division of Medical Sciences, University of Oxford, Oxford, United Kingdom
| | - Jeffrey Kyei-Boahen
- Department of Medicine, McGill University Health Centre, CHAL Research Program, Montreal, Canada
| | - Anouar Hafiane
- Department of Medicine, McGill University Health Centre, CHAL Research Program, Montreal, Canada
| | - Girija Daliah
- Department of Medicine, McGill University Health Centre, Cancer Research Program, Montreal, Canada
| | - Célia Alecki
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Tayah S Hopes
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Martin Heier
- Department of Clinical Neuroscience for Children, Oslo University Hospital, Oslo, Norway
| | - Irene A Aligianis
- Medical and Developmental Genetics, Medical Research Council Human Genetics Unit, Edinburgh, United Kingdom
| | - Jean-Jacques Lebrun
- Department of Medicine, McGill University Health Centre, Cancer Research Program, Montreal, Canada
| | - Julie Aspden
- Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Emanuele Paci
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Anja Kerksiek
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - Peter Clayton
- Genetics and Genomic Medicine, Great Ormond Street Institute of Child Health, University College London, London, United Kingdom
| | - Jimi C Wills
- Cancer Research United Kingdom Edinburgh Centre, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom; Firefinch Software Ltd, Edinburgh, United Kingdom
| | - Alex von Kriegsheim
- Cancer Research United Kingdom Edinburgh Centre, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, United Kingdom
| | - Tommy Nilsson
- Cancer Research Program (CRP), Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Eamonn Sheridan
- Leeds Institute of Medical Research, St James's University Hospital, Leeds, United Kingdom
| | - Mark T Handley
- Leeds Institute of Medical Research, St James's University Hospital, Leeds, United Kingdom; Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.
| |
Collapse
|
32
|
Giedt MS, Thomalla JM, White RP, Johnson MR, Lai ZW, Tootle TL, Welte MA. Adipose triglyceride lipase promotes prostaglandin-dependent actin remodeling by regulating substrate release from lipid droplets. Development 2023; 150:dev201516. [PMID: 37306387 PMCID: PMC10281261 DOI: 10.1242/dev.201516] [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: 12/07/2022] [Accepted: 05/03/2023] [Indexed: 05/13/2023]
Abstract
Lipid droplets (LDs), crucial regulators of lipid metabolism, accumulate during oocyte development. However, their roles in fertility remain largely unknown. During Drosophila oogenesis, LD accumulation coincides with the actin remodeling necessary for follicle development. Loss of the LD-associated Adipose Triglyceride Lipase (ATGL) disrupts both actin bundle formation and cortical actin integrity, an unusual phenotype also seen when the prostaglandin (PG) synthase Pxt is missing. Dominant genetic interactions and PG treatment of follicles indicate that ATGL acts upstream of Pxt to regulate actin remodeling. Our data suggest that ATGL releases arachidonic acid (AA) from LDs to serve as the substrate for PG synthesis. Lipidomic analysis detects AA-containing triglycerides in ovaries, and these are increased when ATGL is lost. High levels of exogenous AA block follicle development; this is enhanced by impairing LD formation and suppressed by reducing ATGL. Together, these data support the model that AA stored in LD triglycerides is released by ATGL to drive the production of PGs, which promote the actin remodeling necessary for follicle development. We speculate that this pathway is conserved across organisms to regulate oocyte development and promote fertility.
Collapse
Affiliation(s)
- Michelle S. Giedt
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | | | - Roger P. White
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Matthew R. Johnson
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Zon Weng Lai
- Harvard T.H. Chan Advanced Multi-omics Platform, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Tina L. Tootle
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Michael A. Welte
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| |
Collapse
|
33
|
Abstract
The sorting and trafficking of lipids between organelles gives rise to a dichotomy of bulk membrane properties between organelles of the secretory and endolysosome networks, giving rise to two "membrane territories" based on differences in lipid-packing density, net membrane charge, and bilayer leaflet asymmetries. The cellular organelle membrane dichotomy emerges from ER-to-PM anterograde membrane trafficking and the synthesis of sphingolipids and cholesterol flux at the trans-Golgi network, which constitutes the interface between the two membrane territories. Organelle homeostasis is maintained by vesicle-mediated retrieval of bulk membrane from the distal organelles of each territory to the endoplasmic reticulum or plasma membrane and by soluble lipid transfer proteins that traffic particular lipids. The concept of cellular membrane territories emphasizes the contrasting features of organelle membranes of the secretory and endolysosome networks and the essential roles of lipid-sorting pathways that maintain organelle function.
Collapse
Affiliation(s)
- Yeongho Kim
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Christopher G Burd
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| |
Collapse
|
34
|
Kataoka-Hamai C, Kawakami K. Ostwald Ripening of Triacylglycerol Droplets Embedded in Glass-Supported Phospholipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:10001-10010. [PMID: 37433207 DOI: 10.1021/acs.langmuir.3c00835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Abstract
Lipid droplets are fat storage organelles that consist of a neutral lipid core surrounded by a phospholipid monolayer. Because of their important biological functions, reconstituting model lipid droplets in synthetic phospholipid membranes is of great interest. In the present study, we investigated the incorporation of triacylglycerol droplets into glass-supported phospholipid bilayers by using fluorescence microscopy. We adsorbed triolein emulsions onto a glass surface that was partially covered with planar bilayers. After adsorption, triolein droplets were found to be immobilized in the bilayer membrane. The volume of each bound droplet varied over time. Large droplets grew, whereas small droplets shrank. Additionally, data on fluorescence recovery after photobleaching obtained for a phospholipid probe indicate that phospholipids on and near triolein droplets were fully mobile. Furthermore, photobleaching data obtained for a triacylglycerol probe indicate that triolein molecules diffused between different droplets along the planar bilayer. These results demonstrate Ostwald ripening, where triolein molecules in a small droplet dissolved in the bilayer, diffused laterally, and eventually bound to the interfaces of larger droplets. We investigated the ripening rate by using the average of the cube root of the fluorescence emission obtained for individual droplets. The ripening slowed after the addition of trilinolein to the triolein phase. Finally, we investigated the time dependence of the size distributions of the triolein droplets. The distribution was initially nearly unimodal and subsequently became bimodal.
Collapse
Affiliation(s)
- Chiho Kataoka-Hamai
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Kohsaku Kawakami
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
| |
Collapse
|
35
|
Dalen KT, Li Y. Regulation of lipid droplets and cholesterol metabolism in adrenal cortical cells. VITAMINS AND HORMONES 2023; 124:79-136. [PMID: 38408810 DOI: 10.1016/bs.vh.2023.06.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
The adrenal gland is composed of two distinctly different endocrine moieties. The interior medulla consists of neuroendocrine chromaffin cells that secrete catecholamines like adrenaline and noradrenaline, while the exterior cortex consists of steroidogenic cortical cells that produce steroid hormones, such as mineralocorticoids (aldosterone), glucocorticoids (cortisone and cortisol) and androgens. Synthesis of steroid hormones in cortical cells requires substantial amounts of cholesterol, which is the common precursor for steroidogenesis. Cortical cells may acquire cholesterol from de novo synthesis and uptake from circulating low- and high-density lipoprotein particles (LDL and HDL). As cholesterol is part of the plasma membrane in all mammalian cells and an important regulator of membrane fluidity, cellular levels of free cholesterol are tightly regulated. To ensure a robust supply of cholesterol for steroidogenesis and to avoid cholesterol toxicity, cortical cells store large amounts of cholesterol as cholesteryl esters in intracellular lipid droplets. Cortical steroidogenesis relies on both mobilization of cholesterol from lipid droplets and constant uptake of circulating cholesterol to replenish lipid droplet stores. This chapter will describe mechanisms involved in cholesterol uptake, cholesteryl ester synthesis, lipid droplet formation, hydrolysis of stored cholesteryl esters, as well as their impact on steroidogenesis. Additionally, animal models and human diseases characterized by altered cortical cholesteryl ester storage, with or without abnormal steroidogenesis, will be discussed.
Collapse
Affiliation(s)
- Knut Tomas Dalen
- Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Norway; The Norwegian Transgenic Center, Institute of Basic Medical Sciences, University of Oslo, Norway.
| | - Yuchuan Li
- Department of Hepato-Pancreato-Biliary Surgery, Institute of Clinical Medicine, University of Oslo, Norway
| |
Collapse
|
36
|
Walther TC, Kim S, Arlt H, Voth GA, Farese RV. Structure and function of lipid droplet assembly complexes. Curr Opin Struct Biol 2023; 80:102606. [PMID: 37150040 PMCID: PMC10853036 DOI: 10.1016/j.sbi.2023.102606] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 04/03/2023] [Accepted: 04/10/2023] [Indexed: 05/09/2023]
Abstract
Cells store lipids as a reservoir of metabolic energy and membrane component precursors in organelles called lipid droplets (LDs). LD formation occurs in the endoplasmic reticulum (ER) at LD assembly complexes (LDAC), consisting of an oligomeric core of seipin and accessory proteins. LDACs determine the sites of LD formation and are required for this process to occur normally. Seipin oligomers form a cage-like structure in the membrane that may serve to facilitate the phase transition of neutral lipids in the membrane to form an oil droplet within the LDAC. Modeling suggests that, as the LD grows, seipin anchors it to the ER bilayer and conformational shifts of seipin transmembrane segments open the LDAC dome toward the cytoplasm, enabling the emerging LD to egress from the ER.
Collapse
Affiliation(s)
- Tobias C Walther
- Cell Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA; Howard Hughes Medical Institute, New York, NY 10065, USA.
| | - Siyoung Kim
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA
| | - Henning Arlt
- Howard Hughes Medical Institute, New York, NY 10065, USA
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, 60637, USA
| | - Robert V Farese
- Cell Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| |
Collapse
|
37
|
Henne WM. The (social) lives, deaths, and biophysical phases of lipid droplets. Curr Opin Cell Biol 2023; 82:102178. [PMID: 37295067 PMCID: PMC10782554 DOI: 10.1016/j.ceb.2023.102178] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023]
Abstract
Lipid droplets (LDs) are major lipid storage organelles, sequestering energy-rich triglycerides and serving as nutrient sinks for cellular homeostasis. Observed for over a century but generally ignored, LDs are now appreciated to play key roles in organismal physiology and disease. They also form numerous functional contacts with other organelles. Here, we highlight recent studies examining LDs from distinct perspectives of their life cycle: their biogenesis, "social" life as they interact with other organelles, and deaths via lipolysis or lipophagy. We also discuss recent work showing how changes in LD lipid content alter the biophysical phases of LD lipids, and how this may fine-tune the LD protein landscape and ultimately LD function.
Collapse
Affiliation(s)
- W Mike Henne
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
| |
Collapse
|
38
|
Zadoorian A, Du X, Yang H. Lipid droplet biogenesis and functions in health and disease. Nat Rev Endocrinol 2023:10.1038/s41574-023-00845-0. [PMID: 37221402 DOI: 10.1038/s41574-023-00845-0] [Citation(s) in RCA: 83] [Impact Index Per Article: 83.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/25/2023] [Indexed: 05/25/2023]
Abstract
Ubiquitous yet unique, lipid droplets are intracellular organelles that are increasingly being recognized for their versatility beyond energy storage. Advances uncovering the intricacies of their biogenesis and the diversity of their physiological and pathological roles have yielded new insights into lipid droplet biology. Despite these insights, the mechanisms governing the biogenesis and functions of lipid droplets remain incompletely understood. Moreover, the causal relationship between the biogenesis and function of lipid droplets and human diseases is poorly resolved. Here, we provide an update on the current understanding of the biogenesis and functions of lipid droplets in health and disease, highlighting a key role for lipid droplet biogenesis in alleviating cellular stresses. We also discuss therapeutic strategies of targeting lipid droplet biogenesis, growth or degradation that could be applied in the future to common diseases, such as cancer, hepatic steatosis and viral infection.
Collapse
Affiliation(s)
- Armella Zadoorian
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia.
| |
Collapse
|
39
|
Farese RV, Walther TC. Glycerolipid Synthesis and Lipid Droplet Formation in the Endoplasmic Reticulum. Cold Spring Harb Perspect Biol 2023; 15:a041246. [PMID: 36096640 PMCID: PMC10153804 DOI: 10.1101/cshperspect.a041246] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
More than 60 years ago, Eugene Kennedy and coworkers elucidated the endoplasmic reticulum (ER)-based pathways of glycerolipid synthesis, including the synthesis of phospholipids and triacylglycerols (TGs). The reactions of the Kennedy pathway were identified by studying the conversion of lipid intermediates and the isolation of biochemical enzymatic activities, but the molecular basis for most of these reactions was unknown. With recent progress in the cell biology, biochemistry, and structural biology in this area, we have a much more mechanistic understanding of this pathway and its reactions. In this review, we provide an overview of molecular aspects of glycerolipid synthesis, focusing on recent insights into the synthesis of TGs. Further, we go beyond the Kennedy pathway to describe the mechanisms for storage of TG in cytosolic lipid droplets and discuss how overwhelming these pathways leads to ER stress and cellular toxicity, as seen in diseases linked to lipid overload and obesity.
Collapse
Affiliation(s)
- Robert V Farese
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115, USA
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, USA
- Center for Causes and Prevention of Cardiovascular Disease (CAP-CVD), Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115, USA
| | - Tobias C Walther
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115, USA
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
- Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142, USA
- Center for Causes and Prevention of Cardiovascular Disease (CAP-CVD), Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115, USA
- Howard Hughes Medical Institute Boston, Boston, Massachusetts 02115, USA
| |
Collapse
|
40
|
Cholesterol esters form supercooled lipid droplets whose nucleation is facilitated by triacylglycerols. Nat Commun 2023; 14:915. [PMID: 36807572 PMCID: PMC9938224 DOI: 10.1038/s41467-023-36375-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 01/27/2023] [Indexed: 02/19/2023] Open
Abstract
Cellular cholesterol can be metabolized to its fatty acid esters, cholesteryl esters (CEs), to be stored in lipid droplets (LDs). With triacylglycerols (TGs), CEs represent the main neutral lipids in LDs. However, while TG melts at ~4 °C, CE melts at ~44 °C, raising the question of how CE-rich LDs form in cells. Here, we show that CE forms supercooled droplets when the CE concentration in LDs is above 20% to TG and, in particular, liquid-crystalline phases when the fraction of CEs is above 90% at 37 °C. In model bilayers, CEs condense and nucleate droplets when the CE/phospholipid ratio reaches over 10-15%. This concentration is reduced by TG pre-clusters in the membrane that thereby facilitate CE nucleation. Accordingly, blocking TG synthesis in cells is sufficient to strongly dampen CE LD nucleation. Finally, CE LDs emerged at seipins, which cluster and nucleate TG LDs in the ER. However, when TG synthesis is inhibited, similar numbers of LDs are generated in the presence and absence of seipin, suggesting that seipin controls CE LD formation via its TG clustering capacity. Our data point to a unique model whereby TG pre-clusters, favorable at seipins, catalyze the nucleation of CE LDs.
Collapse
|
41
|
Salo VT. Seipin-still a mysterious protein? Front Cell Dev Biol 2023; 11:1112954. [PMID: 36819093 PMCID: PMC9935593 DOI: 10.3389/fcell.2023.1112954] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/17/2023] [Indexed: 02/05/2023] Open
Abstract
Cells store excess energy in the form of lipid droplets (LDs), a specialized sub-compartment of the endoplasmic reticulum (ER) network. The lipodystrophy protein seipin is a key player in LD biogenesis and ER-LD contact site maintenance. Recent structural and in silico studies have started to shed light on the molecular function of seipin as a LD nucleator in early LD biogenesis, whilst new cell biological work implies a role for seipin in ER-mitochondria contact sites and calcium metabolism. In this minireview, I discuss recent insights into the molecular function of seipin.
Collapse
|
42
|
Raas Q, Tawbeh A, Tahri-Joutey M, Gondcaille C, Keime C, Kaiser R, Trompier D, Nasser B, Leoni V, Bellanger E, Boussand M, Hamon Y, Benani A, Di Cara F, Truntzer C, Cherkaoui-Malki M, Andreoletti P, Savary S. Peroxisomal defects in microglial cells induce a disease-associated microglial signature. Front Mol Neurosci 2023; 16:1170313. [PMID: 37138705 PMCID: PMC10149961 DOI: 10.3389/fnmol.2023.1170313] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 03/27/2023] [Indexed: 05/05/2023] Open
Abstract
Microglial cells ensure essential roles in brain homeostasis. In pathological condition, microglia adopt a common signature, called disease-associated microglial (DAM) signature, characterized by the loss of homeostatic genes and the induction of disease-associated genes. In X-linked adrenoleukodystrophy (X-ALD), the most common peroxisomal disease, microglial defect has been shown to precede myelin degradation and may actively contribute to the neurodegenerative process. We previously established BV-2 microglial cell models bearing mutations in peroxisomal genes that recapitulate some of the hallmarks of the peroxisomal β-oxidation defects such as very long-chain fatty acid (VLCFA) accumulation. In these cell lines, we used RNA-sequencing and identified large-scale reprogramming for genes involved in lipid metabolism, immune response, cell signaling, lysosome and autophagy, as well as a DAM-like signature. We highlighted cholesterol accumulation in plasma membranes and observed autophagy patterns in the cell mutants. We confirmed the upregulation or downregulation at the protein level for a few selected genes that mostly corroborated our observations and clearly demonstrated increased expression and secretion of DAM proteins in the BV-2 mutant cells. In conclusion, the peroxisomal defects in microglial cells not only impact on VLCFA metabolism but also force microglial cells to adopt a pathological phenotype likely representing a key contributor to the pathogenesis of peroxisomal disorders.
Collapse
Affiliation(s)
- Quentin Raas
- Laboratoire Bio-PeroxIL EA7270, University of Bourgogne, Dijon, France
| | - Ali Tawbeh
- Laboratoire Bio-PeroxIL EA7270, University of Bourgogne, Dijon, France
| | - Mounia Tahri-Joutey
- Laboratoire Bio-PeroxIL EA7270, University of Bourgogne, Dijon, France
- Laboratory of Biochemistry, Neurosciences, Natural Resources and Environment, Faculty of Sciences and Techniques, University Hassan I, Settat, Morocco
| | | | - Céline Keime
- Plateforme GenomEast, IGBMC, CNRS UMR 7104, Inserm U1258, University of Strasbourg, Illkirch, France
| | - Romain Kaiser
- Plateforme GenomEast, IGBMC, CNRS UMR 7104, Inserm U1258, University of Strasbourg, Illkirch, France
| | - Doriane Trompier
- Laboratoire Bio-PeroxIL EA7270, University of Bourgogne, Dijon, France
| | - Boubker Nasser
- Laboratory of Biochemistry, Neurosciences, Natural Resources and Environment, Faculty of Sciences and Techniques, University Hassan I, Settat, Morocco
| | - Valerio Leoni
- Laboratory of Clinical Biochemistry, Hospital of Desio, ASST-Brianza and Department of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Emma Bellanger
- Aix Marseille Univ, CNRS, INSERM, CIML, Marseille, France
| | - Maud Boussand
- Aix Marseille Univ, CNRS, INSERM, CIML, Marseille, France
| | - Yannick Hamon
- Aix Marseille Univ, CNRS, INSERM, CIML, Marseille, France
| | - Alexandre Benani
- Centre des Sciences du Goût et de l’Alimentation, CNRS, INRAE, Institut Agro Dijon, University of Bourgogne Franche-Comté, Dijon, France
| | - Francesca Di Cara
- Department of Microbiology and Immunology, IWK Health Centre, Dalhousie University, Halifax, NS, Canada
| | - Caroline Truntzer
- Platform of Transfer in Biological Oncology, Georges François Leclerc Cancer Center–Unicancer, Dijon, France
| | | | | | - Stéphane Savary
- Laboratoire Bio-PeroxIL EA7270, University of Bourgogne, Dijon, France
- *Correspondence: Stéphane Savary,
| |
Collapse
|
43
|
Florance I, Ramasubbu S. Current Understanding on the Role of Lipids in Macrophages and Associated Diseases. Int J Mol Sci 2022; 24:ijms24010589. [PMID: 36614031 PMCID: PMC9820199 DOI: 10.3390/ijms24010589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 11/30/2022] [Accepted: 12/09/2022] [Indexed: 12/31/2022] Open
Abstract
Lipid metabolism is the major intracellular mechanism driving a variety of cellular functions such as energy storage, hormone regulation and cell division. Lipids, being a primary component of the cell membrane, play a pivotal role in the survival of macrophages. Lipids are crucial for a variety of macrophage functions including phagocytosis, energy balance and ageing. However, functions of lipids in macrophages vary based on the site the macrophages are residing at. Lipid-loaded macrophages have recently been emerging as a hallmark for several diseases. This review discusses the significance of lipids in adipose tissue macrophages, tumor-associated macrophages, microglia and peritoneal macrophages. Accumulation of macrophages with impaired lipid metabolism is often characteristically observed in several metabolic disorders. Stress signals differentially regulate lipid metabolism. While conditions such as hypoxia result in accumulation of lipids in macrophages, stress signals such as nutrient deprivation initiate lipolysis and clearance of lipids. Understanding the biology of lipid accumulation in macrophages requires the development of potentially active modulators of lipid metabolism.
Collapse
|
44
|
Li J, Wang J, Zhu Y, Zhu X, Yu Z, Zhang J, Wang L, Yu J, Liu Z, Zhou H. A FLIM photosensitizer: Targeting “Affinal” suborganelles to accelerate cancer cell oxidative stress and apoptosis. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.114164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
45
|
Lukmantara I, Chen F, Mak HY, Zadoorian A, Du X, Xiao FN, Norris DM, Pandzic E, Whan R, Zhong Q, Yang H. PI(3)P and DFCP1 regulate the biogenesis of lipid droplets. Mol Biol Cell 2022; 33:ar131. [PMID: 36129766 PMCID: PMC9727793 DOI: 10.1091/mbc.e22-07-0279] [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] [Indexed: 02/04/2023] Open
Abstract
The biogenesis of lipid droplets (LDs), key organelles for cellular lipid storage and homeostasis, remains poorly understood. Seipin is essential to normal LD biogenesis but exactly how it regulates LD initiation remains to be elucidated. Our previous results suggested that seipin may bind anionic phospholipids such as PI(3)P. Here, we investigate whether PI(3)P is functionally linked to seipin and whether PI(3)P can also impact LD biogenesis. In seipin-deficient cells, there were enlarged PI(3)P puncta where its effector, DFCP1, also appeared to congregate. Reducing cellular PI(3)P partially rescued the defective LD initiation caused by seipin deficiency. Increasing PI(3)P impeded the lipidation of nascent LDs. We further demonstrated that DFCP1 localized to LDs and facilitated the efficient lipidation of nascent LDs. However, the normal function and localization of DFCP1 were disrupted when cellular PI(3)P homeostasis was perturbed. Our results thus identify PI(3)P as a novel regulator of LD initiation and suggest that PI(3)P may impact the biogenesis of LDs through DFCP1.
Collapse
Affiliation(s)
- Ivan Lukmantara
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Fang Chen
- Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China
| | - Hoi Yin Mak
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Armella Zadoorian
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Ximing Du
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Fanqian Nicole Xiao
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Dougall MacMurray Norris
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Elvis Pandzic
- Katharina Gaus Light Microscopy Facility, Mark Wainwright Analytical Center, University of New South Wales, Sydney, NSW 2052, Australia
| | - Renee Whan
- Katharina Gaus Light Microscopy Facility, Mark Wainwright Analytical Center, University of New South Wales, Sydney, NSW 2052, Australia
| | - Qing Zhong
- Key Laboratory of Cell Differentiation and Apoptosis of the Chinese Ministry of Education, Department of Pathophysiology, Shanghai Jiao Tong University School of Medicine, Shanghai 200240, China
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia,*Address correspondence to: Hongyuan Yang ()
| |
Collapse
|
46
|
Guyard V, Monteiro-Cardoso VF, Omrane M, Sauvanet C, Houcine A, Boulogne C, Ben Mbarek K, Vitale N, Faklaris O, El Khallouki N, Thiam AR, Giordano F. ORP5 and ORP8 orchestrate lipid droplet biogenesis and maintenance at ER-mitochondria contact sites. J Cell Biol 2022; 221:e202112107. [PMID: 35969857 PMCID: PMC9375143 DOI: 10.1083/jcb.202112107] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 05/30/2022] [Accepted: 07/05/2022] [Indexed: 12/29/2022] Open
Abstract
Lipid droplets (LDs) are the primary organelles of lipid storage, buffering energy fluctuations of the cell. They store neutral lipids in their core that is surrounded by a protein-decorated phospholipid monolayer. LDs arise from the endoplasmic reticulum (ER). The ER protein seipin, localizing at ER-LD junctions, controls LD nucleation and growth. However, how LD biogenesis is spatially and temporally coordinated remains elusive. Here, we show that the lipid transfer proteins ORP5 and ORP8 control LD biogenesis at mitochondria-associated ER membrane (MAM) subdomains, enriched in phosphatidic acid. We found that ORP5/8 regulates seipin recruitment to these MAM-LD contacts, and their loss impairs LD biogenesis. Importantly, the integrity of ER-mitochondria contact sites is crucial for ORP5/8 function in regulating seipin-mediated LD biogenesis. Our study uncovers an unprecedented ORP5/8 role in orchestrating LD biogenesis and maturation at MAMs and brings novel insights into the metabolic crosstalk between mitochondria, ER, and LDs at the membrane contact sites.
Collapse
Affiliation(s)
- Valentin Guyard
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inserm U1280, Gif-sur-Yvette, France
| | - Vera Filipa Monteiro-Cardoso
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inserm U1280, Gif-sur-Yvette, France
| | - Mohyeddine Omrane
- Laboratoire de Physique de l’École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, Paris, France
| | - Cécile Sauvanet
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inserm U1280, Gif-sur-Yvette, France
| | - Audrey Houcine
- Institut Jacques Monod, CNRS, UMR7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Claire Boulogne
- Imagerie-Gif, Electron Microscopy Facility, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Kalthoum Ben Mbarek
- Laboratoire de Physique de l’École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, Paris, France
| | - Nicolas Vitale
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, UPR-321267000 Strasbourg, France
| | - Orestis Faklaris
- MRI, BioCampus Montpellier, CRBM, Univ. Montpellier, CNRS, Montpellier, France
| | - Naima El Khallouki
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inserm U1280, Gif-sur-Yvette, France
| | - Abdou Rachid Thiam
- Laboratoire de Physique de l’École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris Cité, Paris, France
| | - Francesca Giordano
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, France
- Inserm U1280, Gif-sur-Yvette, France
| |
Collapse
|
47
|
Apte MS, Joshi AS. Membrane shaping proteins, lipids, and cytoskeleton: Recipe for nascent lipid droplet formation. Bioessays 2022; 44:e2200038. [PMID: 35832014 DOI: 10.1002/bies.202200038] [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: 02/15/2022] [Revised: 06/26/2022] [Accepted: 06/29/2022] [Indexed: 11/06/2022]
Abstract
Lipid droplets (LDs) are ubiquitous, neutral lipidorganelles that act as hubs of metabolic processes. LDs are structurally unique with a hydrophobic core that mainly consists of neutral lipids, sterol esters, and triglycerides, enclosed within a phospholipid monolayer. Nascent LD formation begins with the accumulation of neutral lipids in the endoplasmic reticulum (ER) bilayer. The ER membrane proteins such as seipin, LDAF1, FIT, and MCTPs are reported to play an important role in the formation of nascent LDs. As the LDs grow, they unmix from the highly charged ER membrane to form mature LDs. LD biogenesis is an exciting, emerging research area, and herein, we discuss the recent progress in our understanding of the formation of eukaryotic nascent LDs. We focus on the role of ER membrane shaping proteins such as reticulons and reticulon-like proteins, membrane lipids, and cytoskeleton proteins such as septin in the formation of nascent LDs.
Collapse
Affiliation(s)
- Manasi S Apte
- Department of Biochemistry & Cell and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Amit S Joshi
- Department of Biochemistry & Cell and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| |
Collapse
|
48
|
Li Y, Yang X, Peng L, Xia Q, Zhang Y, Huang W, Liu T, Jia D. Role of Seipin in Human Diseases and Experimental Animal Models. Biomolecules 2022; 12:biom12060840. [PMID: 35740965 PMCID: PMC9221541 DOI: 10.3390/biom12060840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/13/2022] [Accepted: 06/14/2022] [Indexed: 02/05/2023] Open
Abstract
Seipin, a protein encoded by the Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) gene, is famous for its key role in the biogenesis of lipid droplets and type 2 congenital generalised lipodystrophy (CGL2). BSCL2 gene mutations result in genetic diseases including CGL2, progressive encephalopathy with or without lipodystrophy (also called Celia’s encephalopathy), and BSCL2-associated motor neuron diseases. Abnormal expression of seipin has also been found in hepatic steatosis, neurodegenerative diseases, glioblastoma stroke, cardiac hypertrophy, and other diseases. In the current study, we comprehensively summarise phenotypes, underlying mechanisms, and treatment of human diseases caused by BSCL2 gene mutations, paralleled by animal studies including systemic or specific Bscl2 gene knockout, or Bscl2 gene overexpression. In various animal models representing diseases that are not related to Bscl2 mutations, differential expression patterns and functional roles of seipin are also described. Furthermore, we highlight the potential therapeutic approaches by targeting seipin or its upstream and downstream signalling pathways. Taken together, restoring adipose tissue function and targeting seipin-related pathways are effective strategies for CGL2 treatment. Meanwhile, seipin-related pathways are also considered to have potential therapeutic value in diseases that are not caused by BSCL2 gene mutations.
Collapse
Affiliation(s)
- Yuying Li
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
| | - Xinmin Yang
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
| | - Linrui Peng
- Department of Endocrinology and Metabolism, West China Hospital of Sichuan University, Chengdu 610041, China; (L.P.); (Y.Z.)
| | - Qing Xia
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
| | - Yuwei Zhang
- Department of Endocrinology and Metabolism, West China Hospital of Sichuan University, Chengdu 610041, China; (L.P.); (Y.Z.)
| | - Wei Huang
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
- Institutes for Systems Genetics & Immunology and Inflammation, Frontiers Science Center for Disease-Related Molecular Network, West China Hospital, Sichuan University, Chengdu 610041, China
- Correspondence: (W.H.); (T.L.)
| | - Tingting Liu
- West China Pancreatitis Centre, Centre for Integrated Traditional Chinese Medicine and Western Medicine, West China-Liverpool Biomedical Research Centre, West China Hospital, Sichuan University, Chengdu 610041, China; (Y.L.); (X.Y.); (Q.X.)
- Correspondence: (W.H.); (T.L.)
| | - Da Jia
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy and Collaborative Innovation Center of Biotherapy, Sichuan University, Chengdu 610041, China;
| |
Collapse
|
49
|
Sar1 Affects the Localization of Perilipin 2 to Lipid Droplets. Int J Mol Sci 2022; 23:ijms23126366. [PMID: 35742827 PMCID: PMC9223735 DOI: 10.3390/ijms23126366] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/03/2022] [Accepted: 06/03/2022] [Indexed: 02/05/2023] Open
Abstract
Lipid droplets (LDs) are intracellular organelles that are ubiquitous in many types of cells. The LD core consists of triacylglycerols (TGs) surrounded by a phospholipid monolayer and surface proteins such as perilipin 2 (PLIN2). Although TGs accumulate in the phospholipid bilayer of the endoplasmic reticulum (ER) and subsequently nascent LDs buds from ER, the mechanism by which LD proteins are transported to LD particles is not fully understood. Sar1 is a GTPase known as a regulator of coat protein complex Ⅱ (COPⅡ) vesicle budding, and its role in LD formation was investigated in this study. HuH7 human hepatoma cells were infected with adenoviral particles containing genes coding GFP fused with wild-type Sar1 (Sar1 WT) or a GTPase mutant form (Sar1 H79G). When HuH7 cells were treated with oleic acid, Sar1 WT formed a ring-like structure around the LDs. The transient expression of Sar1 did not significantly alter the levels of TG and PLIN2 in the cells. However, the localization of PLIN2 to the LDs decreased in the cells expressing Sar1 H79G. Furthermore, the effects of Sar1 on PLIN2 localization to the LDs were verified by the suppression of endogenous Sar1 using the short hairpin RNA technique. In conclusion, it was found that Sar1 has some roles in the intracellular distribution of PLIN2 to LDs in liver cells.
Collapse
|
50
|
Krawczyk HE, Sun S, Doner NM, Yan Q, Lim MSS, Scholz P, Niemeyer PW, Schmitt K, Valerius O, Pleskot R, Hillmer S, Braus GH, Wiermer M, Mullen RT, Ischebeck T. SEED LIPID DROPLET PROTEIN1, SEED LIPID DROPLET PROTEIN2, and LIPID DROPLET PLASMA MEMBRANE ADAPTOR mediate lipid droplet-plasma membrane tethering. THE PLANT CELL 2022; 34:2424-2448. [PMID: 35348751 PMCID: PMC9134073 DOI: 10.1093/plcell/koac095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 02/14/2022] [Indexed: 05/27/2023]
Abstract
Membrane contact sites (MCSs) are interorganellar connections that allow for the direct exchange of molecules, such as lipids or Ca2+ between organelles, but can also serve to tether organelles at specific locations within cells. Here, we identified and characterized three proteins of Arabidopsis thaliana that form a lipid droplet (LD)-plasma membrane (PM) tethering complex in plant cells, namely LD-localized SEED LD PROTEIN (SLDP) 1 and SLDP2 and PM-localized LD-PLASMA MEMBRANE ADAPTOR (LIPA). Using proteomics and different protein-protein interaction assays, we show that both SLDPs associate with LIPA. Disruption of either SLDP1 and SLDP2 expression, or that of LIPA, leads to an aberrant clustering of LDs in Arabidopsis seedlings. Ectopic co-expression of one of the SLDPs with LIPA is sufficient to reconstitute LD-PM tethering in Nicotiana tabacum pollen tubes, a cell type characterized by dynamically moving LDs in the cytosolic streaming. Furthermore, confocal laser scanning microscopy revealed both SLDP2.1 and LIPA to be enriched at LD-PM contact sites in seedlings. These and other results suggest that SLDP and LIPA interact to form a tethering complex that anchors a subset of LDs to the PM during post-germinative seedling growth in Arabidopsis.
Collapse
Affiliation(s)
- Hannah Elisa Krawczyk
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Siqi Sun
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Nathan M Doner
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Qiqi Yan
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Molecular Biology of Plant-Microbe Interactions Research Group, University of Göttingen, Göttingen, Germany
| | - Magdiel Sheng Satha Lim
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Patricia Scholz
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Philipp William Niemeyer
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
| | - Kerstin Schmitt
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Oliver Valerius
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Roman Pleskot
- Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic
| | - Stefan Hillmer
- Electron Microscopy Core Facility, Heidelberg University, Heidelberg, Germany
| | - Gerhard H Braus
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences (GZMB) and Service Unit LCMS Protein Analytics, Department for Molecular Microbiology and Genetics, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Marcel Wiermer
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Molecular Biology of Plant-Microbe Interactions Research Group, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Till Ischebeck
- Albrecht-von-Haller-Institute for Plant Sciences and Göttingen Center for Molecular Biosciences (GZMB), Department of Plant Biochemistry, University of Göttingen, Göttingen, Germany
- Göttingen Center for Molecular Biosciences (GZMB), University of Göttingen, Göttingen, Germany
- Institute of Plant Biology and Biotechnology (IBBP), Green Biotechnology, University of Münster, Münster, Germany
| |
Collapse
|