1
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Garaiova M, Ding Y, Holic R, Valachovic M, Zhang C, Hapala I, Liu P. Yeast perilipin Pet10p/Pln1p interacts with Erg6p in ergosterol metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159506. [PMID: 38734059 DOI: 10.1016/j.bbalip.2024.159506] [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: 05/06/2023] [Revised: 05/03/2024] [Accepted: 05/08/2024] [Indexed: 05/13/2024]
Abstract
Lipid droplets (LD) are highly dynamic organelles specialized for the regulation of energy storage and cellular homeostasis. LD consist of a neutral lipid core surrounded by a phospholipid monolayer membrane with embedded proteins, most of which are involved in lipid homeostasis. In this study, we focused on one of the major LD proteins, sterol C24-methyltransferase, encoded by ERG6. We found that the absence of Erg6p resulted in an increased accumulation of yeast perilipin Pet10p in LD, while the disruption of PET10 was accompanied by Erg6p LD over-accumulation. An observed reciprocal enrichment of Erg6p and Pet10p in pet10Δ and erg6Δ mutants in LD, respectively, was related to specific functional changes in the LD and was not due to regulation on the expression level. The involvement of Pet10p in neutral lipid homeostasis was observed in experiments that focused on the dynamics of neutral lipid mobilization as time-dependent changes in the triacylglycerols (TAG) and steryl esters (SE) content. We found that the kinetics of SE hydrolysis was reduced in erg6Δ cells and the mobilization of SE was completely lost in mutants that lacked both Erg6p and Pet10p. In addition, we observed that decreased levels of SE in erg6Δpet10Δ was linked to an overexpression of steryl ester hydrolase Yeh1p. Lipid analysis of erg6Δpet10Δ showed that PET10 deletion altered the composition of ergosterol intermediates which had accumulated in erg6Δ. In conclusion, yeast perilipin Pet10p functionally interacts with Erg6p during the metabolism of ergosterol.
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Affiliation(s)
- Martina Garaiova
- Department of Biochemistry of Biomembranes, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava 840 05, Slovakia.
| | - Yunfeng Ding
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Roman Holic
- Department of Biochemistry of Biomembranes, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava 840 05, Slovakia
| | - Martin Valachovic
- Department of Biochemistry of Biomembranes, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava 840 05, Slovakia
| | - Congyan Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ivan Hapala
- Department of Biochemistry of Biomembranes, Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava 840 05, Slovakia
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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2
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Fujimoto T. Nuclear lipid droplet: Guardian of nuclear membrane lipid homeostasis? Curr Opin Cell Biol 2024; 88:102370. [PMID: 38744005 DOI: 10.1016/j.ceb.2024.102370] [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: 03/15/2024] [Accepted: 04/22/2024] [Indexed: 05/16/2024]
Abstract
Lipid droplets (LDs) are cytoplasmic organelles, but they are also found within the nucleus in small numbers. Nuclear LDs that form at the inner nuclear membrane (INM) often increase in response to perturbation in phosphatidic acid (PA) and/or diacylglycerol (DAG), both implicated in various INM functions. Nuclear LDs also increase upon downregulation of seipin, a protein that can trap PA and DAG in the endoplasmic reticulum. Notably, both PA and DAG appear to be more densely distributed on the surface of nuclear LDs than in the INM. I propose that nuclear LDs play a role in regulating the PA and DAG level in the INM, thereby contributing to the lipid homeostasis in this compartment.
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Affiliation(s)
- Toyoshi Fujimoto
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. mailto:
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3
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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.
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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
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4
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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.
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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
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5
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Klug YA, Ferreira JV, Carvalho P. A unifying mechanism for seipin-mediated lipid droplet formation. FEBS Lett 2024; 598:1116-1126. [PMID: 38785192 DOI: 10.1002/1873-3468.14825] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/13/2024] [Accepted: 01/23/2024] [Indexed: 05/25/2024]
Abstract
Lipid droplets (LDs) are dynamic organelles essential for cellular lipid homeostasis. Assembly of LDs occurs in the endoplasmic reticulum (ER), and the conserved ER membrane protein seipin emerged as a key player in this process. Here, we review recent advances provided by structural, biochemical, and in silico analysis that revealed mechanistic insights into the molecular role of the seipin complexes and led to an updated model for LD biogenesis. We further discuss how other ER components cooperate with seipin during LD biogenesis. Understanding the molecular mechanisms underlying seipin-mediated LD assembly is important to uncover the fundamental aspects of lipid homeostasis and organelle biogenesis and to provide hints on the pathogenesis of lipid storage disorders.
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Affiliation(s)
- Yoel A Klug
- Sir William Dunn School of Pathology, University of Oxford, UK
| | | | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, UK
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6
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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.
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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
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7
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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.
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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.
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8
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Hsia JZ, Liu D, Haynes L, Cruz-Cosme R, Tang Q. Lipid Droplets: Formation, Degradation, and Their Role in Cellular Responses to Flavivirus Infections. Microorganisms 2024; 12:647. [PMID: 38674592 PMCID: PMC11051834 DOI: 10.3390/microorganisms12040647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 03/18/2024] [Accepted: 03/22/2024] [Indexed: 04/28/2024] Open
Abstract
Lipid droplets (LDs) are cellular organelles derived from the endoplasmic reticulum (ER), serving as lipid storage sites crucial for maintaining cellular lipid homeostasis. Recent attention has been drawn to their roles in viral replication and their interactions with viruses. However, the precise biological functions of LDs in viral replication and pathogenesis remain incompletely understood. To elucidate the interaction between LDs and viruses, it is imperative to comprehend the biogenesis of LDs and their dynamic interactions with other organelles. In this review, we explore the intricate pathways involved in LD biogenies within the cytoplasm, encompassing the uptake of fatty acid from nutrients facilitated by CD36-mediated membranous protein (FABP/FATP)-FA complexes, and FA synthesis via glycolysis in the cytoplasm and the TCL cycle in mitochondria. While LD biogenesis primarily occurs in the ER, matured LDs are intricately linked to multiple organelles. Viral infections can lead to diverse consequences in terms of LD status within cells post-infection, potentially involving the breakdown of LDs through the activation of lipophagy. However, the exact mechanisms underlying LD destruction or accumulation by viruses remain elusive. The significance of LDs in viral replication renders them effective targets for developing broad-spectrum antivirals. Moreover, considering that reducing neutral lipids in LDs is a strategy for anti-obesity treatment, LD depletion may not pose harm to cells. This presents LDs as promising antiviral targets for developing therapeutics that are minimally or non-toxic to the host.
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Affiliation(s)
| | | | | | | | - Qiyi Tang
- Department of Microbiology, Howard University College of Medicine, Washington, DC 20059, USA; (J.Z.H.); (D.L.); (L.H.); (R.C.-C.)
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9
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Qin Z, Zhang Y, Liu S, Zeng W, Zhou J, Xu S. Combining Metabolic Engineering and Lipid Droplet Assembly to Achieve Campesterol Overproduction in Saccharomyces cerevisiae. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:4814-4824. [PMID: 38389392 DOI: 10.1021/acs.jafc.3c09764] [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: 02/24/2024]
Abstract
Campesterol is a kind of important functional food additive. Therefore, stable and efficient campesterol biosynthesis is significant. Herein, we first knocked out the sterol 22-desaturase gene in Saccharomyces cerevisiae and expressed sterol Δ7-reductase from Pangasianodon hypophthalmus, obtaining a strain that produced 6.6 mg/L campesterol. Then, the modular expression of campesterol synthesis enzymes was performed, and a campesterol titer of 88.3 mg/L was achieved. Because campesterol is a lipid-soluble macromolecule, we promoted lipid droplet formation by exploring regulatory factors, and campesterol production was improved to 169.20 mg/L. Next, triacylglycerol lipase was used to achieve compartment campesterol synthesis. After enhancing the expression of sterol Δ7-reductase and screening cations, the campesterol titer reached 438.28 mg/L in a shake flask and 1.44 g/L in a 5 L bioreactor, which represents the highest campesterol titer reported to date. Metabolic regulation combined with lipid droplet engineering may be useful for the synthesis of other steroids as well.
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Affiliation(s)
- Zhijie Qin
- National Engineering Research Center of Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
| | - Yunliang Zhang
- National Engineering Research Center of Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
| | - Song Liu
- National Engineering Research Center of Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
| | - Weizhu Zeng
- National Engineering Research Center of Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
| | - Jingwen Zhou
- National Engineering Research Center of Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
| | - Sha Xu
- National Engineering Research Center of Cereal Fermentation and Food Biomanufacturing, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China
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10
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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.
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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.
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11
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Sreejith P, Lolo S, Patten KR, Gunasinghe M, More N, Pallanck LJ, Bharadwaj R. Nazo, the Drosophila homolog of the NBIA-mutated protein-c19orf12, is required for triglyceride homeostasis. PLoS Genet 2024; 20:e1011137. [PMID: 38335241 PMCID: PMC10883546 DOI: 10.1371/journal.pgen.1011137] [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: 07/17/2023] [Revised: 02/22/2024] [Accepted: 01/12/2024] [Indexed: 02/12/2024] Open
Abstract
Lipid dyshomeostasis has been implicated in a variety of diseases ranging from obesity to neurodegenerative disorders such as Neurodegeneration with Brain Iron Accumulation (NBIA). Here, we uncover the physiological role of Nazo, the Drosophila melanogaster homolog of the NBIA-mutated protein-c19orf12, whose function has been elusive. Ablation of Drosophila c19orf12 homologs leads to dysregulation of multiple lipid metabolism genes. nazo mutants exhibit markedly reduced gut lipid droplet and whole-body triglyceride contents. Consequently, they are sensitive to starvation and oxidative stress. Nazo is required for maintaining normal levels of Perilipin-2, an inhibitor of the lipase-Brummer. Concurrent knockdown of Brummer or overexpression of Perilipin-2 rescues the nazo phenotype, suggesting that this defect, at least in part, may arise from diminished Perilipin-2 on lipid droplets leading to aberrant Brummer-mediated lipolysis. Our findings potentially provide novel insights into the role of c19orf12 as a possible link between lipid dyshomeostasis and neurodegeneration, particularly in the context of NBIA.
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Affiliation(s)
- Perinthottathil Sreejith
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Sara Lolo
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Kristen R Patten
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Maduka Gunasinghe
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Neya More
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
| | - Leo J Pallanck
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Rajnish Bharadwaj
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, New York, United States of America
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12
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Deng Y, Zhu H, Wang Y, Dong Y, Du J, Yu Q, Li M. The Endoplasmic Reticulum-Plasma Membrane Tethering Protein Ice2 Controls Lipid Droplet Size via the Regulation of Phosphatidylcholine in Candida albicans. J Fungi (Basel) 2024; 10:87. [PMID: 38276033 PMCID: PMC10817647 DOI: 10.3390/jof10010087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 01/13/2024] [Accepted: 01/17/2024] [Indexed: 01/27/2024] Open
Abstract
Lipid droplets (LDs) are intracellular organelles that play important roles in cellular lipid metabolism; they change their sizes and numbers in response to both intracellular and extracellular signals. Changes in LD size reflect lipid synthesis and degradation and affect many cellular activities, including energy supply and membrane synthesis. Here, we focused on the function of the endoplasmic reticulum-plasma membrane tethering protein Ice2 in LD dynamics in the fungal pathogen Candida albicans (C. albicans). Nile red staining and size quantification showed that the LD size increased in the ice2Δ/Δ mutant, indicating the critical role of Ice2 in the regulation of LD dynamics. A lipid content analysis further demonstrated that the mutant had lower phosphatidylcholine levels. As revealed with GFP labeling and fluorescence microscopy, the methyltransferase Cho2, which is involved in phosphatidylcholine synthesis, had poorer localization in the plasma membrane in the mutant than in the wild-type strain. Interestingly, the addition of the phosphatidylcholine precursor choline led to the recovery of normal-sized LDs in the mutant. These results indicated that Ice2 regulates LD size by controlling intracellular phosphatidylcholine levels and that endoplasmic reticulum-plasma membrane tethering proteins play a role in lipid metabolism regulation in C. albicans. This study provides significant findings for further investigation of the lipid metabolism in fungi.
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Affiliation(s)
| | | | | | | | | | | | - Mingchun Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (Y.D.); (H.Z.); (Y.W.); (Y.D.); (J.D.)
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13
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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.
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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.
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14
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Venkatesan N, Doskey LC, Malhi H. The Role of Endoplasmic Reticulum in Lipotoxicity during Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) Pathogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2023; 193:1887-1899. [PMID: 37689385 PMCID: PMC10699131 DOI: 10.1016/j.ajpath.2023.08.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/14/2023] [Accepted: 08/18/2023] [Indexed: 09/11/2023]
Abstract
Perturbations in lipid and protein homeostasis induce endoplasmic reticulum (ER) stress in metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease. Lipotoxic and proteotoxic stress can activate the unfolded protein response (UPR) transducers: inositol requiring enzyme1α, PKR-like ER kinase, and activating transcription factor 6α. Collectively, these pathways induce expression of genes that encode functions to resolve the protein folding defect and ER stress by increasing the protein folding capacity of the ER and degradation of misfolded proteins. The ER is also intimately connected with lipid metabolism, including de novo ceramide synthesis, phospholipid and cholesterol synthesis, and lipid droplet formation. Following their activation, the UPR transducers also regulate lipogenic pathways in the liver. With persistent ER stress, cellular adaptation fails, resulting in hepatocyte apoptosis, a pathological marker of liver disease. In addition to the ER-nucleus signaling activated by the UPR, the ER can interact with other organelles via membrane contact sites. Modulating intracellular communication between ER and endosomes, lipid droplets, and mitochondria to restore ER homeostasis could have therapeutic efficacy in ameliorating liver disease. Recent studies have also demonstrated that cells can convey ER stress by the release of extracellular vesicles. This review discusses lipotoxic ER stress and the central role of the ER in communicating ER stress to other intracellular organelles in MASLD pathogenesis.
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Affiliation(s)
- Nanditha Venkatesan
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
| | - Luke C Doskey
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Harmeet Malhi
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota.
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15
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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.
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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.
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16
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Jin Y, Tan Y, Wu J, Ren Z. Lipid droplets: a cellular organelle vital in cancer cells. Cell Death Discov 2023; 9:254. [PMID: 37474495 PMCID: PMC10359296 DOI: 10.1038/s41420-023-01493-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/24/2023] [Accepted: 06/16/2023] [Indexed: 07/22/2023] Open
Abstract
Lipid droplets (LDs) are cellular organelles comprising a core of neutral lipids (glycerides, sterols) encased within a single phospholipid membrane, responsible for storing surplus lipids and furnishing cellular energy. LDs engage in lipid synthesis, catabolism, and transport processes by interacting with other organelles (e.g., endoplasmic reticulum, mitochondria), and they play critical roles in regulating cellular stress and immunity. Recent research has uncovered that an elevated number of LDs is a hallmark of cancer cells, attributable to their enhanced lipid uptake and synthesis capacity, with lipids stored as LDs. Depletion of LDs in cancer cells induces apoptosis, prompting the emergence of small molecule antitumor drugs targeting LDs or key factors (e.g., FASN, SCD1) within the lipid synthesis pathway. Advancements in LD isolation and artificial synthesis have demonstrated their potential applicability in antitumor research. LDs extracted from murine adipose tissue and incubated with lipophilic antitumor drugs yield drug-coated LDs, which promote apoptosis in cancer cells. Furthermore, LDs have been employed as biological lenses to augment the resolution of subcellular structures (microfilaments, microtubules), facilitating the observation of intricate structures within thicker cells, including cancer cells. This review delineates the functional and metabolic mechanisms of LDs in cancer cells and encapsulates recent progress in LD-centered antitumor research, offering novel insights for tumor diagnosis and treatment.
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Affiliation(s)
- Yi Jin
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, P. R. China
| | - Yanjie Tan
- Institute of Biomedical Sciences, Key Laboratory of Animal Resistance Biology of Shandong Province, College of Life Sciences, Shandong Normal University, Jinan, 250014, Shandong, P. R. China
| | - Jian Wu
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, P. R. China
| | - Zhuqing Ren
- Key Laboratory of Agriculture Animal Genetics, Breeding and Reproduction of the Ministry of Education & Key Laboratory of Swine Genetics and Breeding of the Ministry of Agriculture and Rural Affairs, College of Animal Science, Huazhong Agricultural University, Wuhan, 430070, Hubei, P. R. China.
- Hubei Hongshan Laboratory, Wuhan, P. R. China.
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17
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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.
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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
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18
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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: 63] [Impact Index Per Article: 63.0] [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.
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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.
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19
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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: 13] [Impact Index Per Article: 13.0] [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.
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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
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20
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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.
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21
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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.
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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 ()
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22
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Nogueira V, Chang CK, Lan CY, Pereira C, Costa V, Teixeira V. Causative links between ER stress and oxidative damage in a yeast model of human N88S seipinopathy. Free Radic Biol Med 2022; 192:165-181. [PMID: 36126862 DOI: 10.1016/j.freeradbiomed.2022.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/02/2022] [Accepted: 09/13/2022] [Indexed: 11/29/2022]
Abstract
Seipin is encoded by the gene Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) and FLD1/SEI1 in yeast. The gain-of-function N88S mutation in the BSCL2 gene was identified in a cohort of autosomal dominant motor neuron diseases (MNDs) collectively known as seipinopathies. Previous work has shown that this mutation disrupts N-glycosylation, leading to the formation of inclusion bodies (IBs) and contributing to severe Endoplasmic Reticulum (ER) stress and cell death. In this work, we established a humanized yeast model of N88S seipinopathy that recapitulated the formation of IBs and activation of the unfolded protein response (UPR) observed in mammalian systems. Autophagy and the Hrd1-mediated endoplasmic reticulum-associated degradation (ERAD) were fully functional in cells expressing mutant homomers and WT-mutant heteromers of seipin, discarding the possibility that mutant seipin accumulate due to impaired protein quality control systems. Importantly, the N88S seipin form IBs that appear to induce changes in ER morphology, in association with Kar2 chaperone and the Hsp104 disaggregase. For the first time, we have determined that N88S homo-oligomers expressing cells present reduced viability, decreased antioxidant activity and increased oxidative damage associated with loss of mitochondrial membrane potential, higher reactive oxygen species (ROS) levels and lipid peroxidation. This was correlated with the activation of oxidative stress sensor Yap1. Moreover, activation of ERAD and UPR quality control mechanisms were essential for proper cell growth, and crucial to prevent excessive accumulation of ROS in cells expressing N88S homomers solely. Overall, this study provides new insights into the molecular underpinnings of these rare diseases and offers novel targets for potential pharmacological intervention.
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Affiliation(s)
- Verónica Nogueira
- Yeast Signalling Networks, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Che-Kang Chang
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Chung-Yu Lan
- Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 30013, Taiwan; Department of Life Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Clara Pereira
- Yeast Signalling Networks, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Vítor Costa
- Yeast Signalling Networks, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
| | - Vitor Teixeira
- Yeast Signalling Networks, i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
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23
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Qin ZL, Yao QF, Ren H, Zhao P, Qi ZT. Lipid Droplets and Their Participation in Zika Virus Infection. Int J Mol Sci 2022; 23:ijms232012584. [PMID: 36293437 PMCID: PMC9604050 DOI: 10.3390/ijms232012584] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/11/2022] [Accepted: 10/14/2022] [Indexed: 11/23/2022] Open
Abstract
Lipid droplets (LDs) are highly conserved and dynamic intracellular organelles. Their functions are not limited to serving as neutral lipid reservoirs; they also participate in non-energy storage functions, such as cell lipid metabolism, protection from cell stresses, maintaining protein homeostasis, and regulating nuclear function. During a Zika virus (ZIKV) infection, the viruses hijack the LDs to provide energy and lipid sources for viral replication. The co-localization of ZIKV capsid (C) protein with LDs supports its role as a virus replication platform and a key compartment for promoting the generation of progeny virus particles. However, in view of the multiple functions of LDs, their role in ZIKV infection needs further elucidation. Here, we review the basic mechanism of LD biogenesis and biological functions and discuss how ZIKV infection utilizes these effects of LDs to facilitate virus replication, along with the future application strategy of developing new antiviral drugs based on the interaction of ZIKV with LDs.
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24
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Metformin alleviates neurocognitive impairment in aging via activation of AMPK/BDNF/PI3K pathway. Sci Rep 2022; 12:17084. [PMID: 36224264 PMCID: PMC9556637 DOI: 10.1038/s41598-022-20945-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 09/21/2022] [Indexed: 01/04/2023] Open
Abstract
Slowing down age-related neurocognitive impairment has been a challenge. We evaluated the therapeutic effects of metformin in D-galactose-induced aging. Additionally, we studied the potential molecular mechanisms that could be responsible for metformin's anti-aging effects. Thirty male rats were equally divided into: 1-control group, which received saline solution, 2-D-galactose (D-gal) group, which received D-galactose (100 mg/kg/day) by gastric lavage for eight weeks, and 3-D-galactose + Metformin (D-gal + Met) treated group, which received D-galactose + metformin (200 mg/kg/day) by gastric lavage for eight weeks. Neurocognitive assessment was done. Measurement of inflammatory, oxidative stress, and BDNF biomarkers was performed. AMPK and PI3K genes expression were assessed. Hippocampal tissues were dissected for histopathological and immunohistochemical studies. D-gal resulted in neurocognitive impairments, elevation of inflammatory biomarkers, altered oxidative stress markers, decreased BDNF, decreased expression of synaptophysin and Bcl2 with increased expression of Caspase-3, and down-regulation of AMPK and PI3K genes. Neurodegenerative changes were present in the hippocampus. Metformin restored significantly D-gal induced neurodegenerative changes. We concluded that metformin could alleviate age-induced neurocognitive deficit via amelioration of neuroinflammation, attenuation of oxidative stress, reduction of apoptosis, as well as promotion of synaptic plasticity. These mechanisms could be mediated via the activation of the AMPK/BDNF/PI3K pathway.
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25
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Renne MF, Corey RA, Ferreira JV, Stansfeld PJ, Carvalho P. Seipin concentrates distinct neutral lipids via interactions with their acyl chain carboxyl esters. J Cell Biol 2022; 221:e202112068. [PMID: 35938957 PMCID: PMC9365673 DOI: 10.1083/jcb.202112068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 05/28/2022] [Accepted: 07/12/2022] [Indexed: 11/22/2022] Open
Abstract
Lipid droplets (LDs) are essential for cellular lipid homeostasis by storing diverse neutral lipids (NLs), such as triacylglycerol (TAG), steryl esters (SE), and retinyl esters (RE). A proper assembly of TAG-containing LDs at the ER requires Seipin, a conserved protein often mutated in lipodystrophies. Here, we show that the yeast Seipin Sei1 and its partner Ldb16 also promote the storage of other NL in LDs. Importantly, this role of Sei1/Ldb16 is evolutionarily conserved as expression of human-Seipin restored normal SE-containing LDs in yeast Seipin mutants. As in the case of TAG, the formation of SE-containing LDs requires interactions between hydroxyl-residues in human Seipin or yeast Ldb16 with NL carboxyl esters. These findings provide a universal mechanism for Seipin-mediated LD formation and suggest a model for how Seipin distinguishes NLs from aliphatic phospholipid acyl chains in the center of the membrane bilayer.
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Affiliation(s)
- Mike F. Renne
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Robin A. Corey
- Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Phillip J. Stansfeld
- Department of Biochemistry, University of Oxford, Oxford, UK
- School of Life Sciences and Department of Chemistry, University of Warwick, Coventry, UK
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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26
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Identification of two pathways mediating protein targeting from ER to lipid droplets. Nat Cell Biol 2022; 24:1364-1377. [PMID: 36050470 PMCID: PMC9481466 DOI: 10.1038/s41556-022-00974-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 07/05/2022] [Indexed: 11/20/2022]
Abstract
Pathways localizing proteins to their sites of action are essential for eukaryotic cell organization and function. Although mechanisms of protein targeting to many organelles have been defined, how proteins, such as metabolic enzymes, target from the endoplasmic reticulum (ER) to cellular lipid droplets (LDs) is poorly understood. Here we identify two distinct pathways for ER-to-LD protein targeting: early targeting at LD formation sites during formation, and late targeting to mature LDs after their formation. Using systematic, unbiased approaches in Drosophila cells, we identified specific membrane-fusion machinery, including regulators, a tether and SNARE proteins, that are required for the late targeting pathway. Components of this fusion machinery localize to LD–ER interfaces and organize at ER exit sites. We identified multiple cargoes for early and late ER-to-LD targeting pathways. Our findings provide a model for how proteins target to LDs from the ER either during LD formation or by protein-catalysed formation of membrane bridges. Song et al. identify two protein-targeting pathways from the endoplasmic reticulum to (1) early lipid droplets (LDs) and (2) mature lipid droplets. They define key factors mediating the second, late pathway and its many cargoes.
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27
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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; 221:213393. [PMID: 35969857 PMCID: PMC9375143 DOI: 10.1083/jcb.202112107] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [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.
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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,Abdou Rachid Thiam;
| | - 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,Correspondence to Francesca Giordano:
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28
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Li M, Zhou P, Chen M, Yu H, Ye L. Spatiotemporal Regulation of Astaxanthin Synthesis in S. cerevisiae. ACS Synth Biol 2022; 11:2636-2649. [PMID: 35914247 DOI: 10.1021/acssynbio.2c00044] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
As a high-valued antioxidant, astaxanthin biosynthesis using microbial cell factories has attracted increasing attention. However, its lipophilic nature conflicts with the limited storage capacity for lipophilic substances of model microorganisms such as Saccharomyces cerevisiae. Expansion of lipid droplets by enhancing lipid synthesis provides more storage room while diverting the metabolic flux from the target pathway. Therefore, proper spatial regulation is required. In this study, a library of genes related to lipid metabolism were screened using the trifunctional CRISPR system, identifying opi3 and hrd1 as new engineering targets to promote astaxanthin synthesis by moderately rather than excessively upregulating lipid synthesis. The astaxanthin yield reached 9.79 mg/g DCW after lipid engineering and was further improved to 10.21 mg/g DCW by balancing the expression of β-carotene hydroxylase and ketolase. Finally, by combining spatial regulation through lipid droplet engineering and temporal regulation via temperature-responsive pathway expression, 446.4 mg/L astaxanthin was produced in fed-batch fermentation.
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Affiliation(s)
- Min Li
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Pingping Zhou
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.,College of Bioscience and Biotechnology, Yangzhou University, Yangzhou 225009, China
| | - Mingkai Chen
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Hongwei Yu
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Lidan Ye
- Institute of Bioengineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China.,ZJU-Hangzhou Global Scientific and Technological Innovation Center, Hangzhou 311200, China
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29
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Vrijsen S, Vrancx C, Del Vecchio M, Swinnen JV, Agostinis P, Winderickx J, Vangheluwe P, Annaert W. Inter-organellar Communication in Parkinson's and Alzheimer's Disease: Looking Beyond Endoplasmic Reticulum-Mitochondria Contact Sites. Front Neurosci 2022; 16:900338. [PMID: 35801175 PMCID: PMC9253489 DOI: 10.3389/fnins.2022.900338] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 05/05/2022] [Indexed: 01/13/2023] Open
Abstract
Neurodegenerative diseases (NDs) are generally considered proteinopathies but whereas this may initiate disease in familial cases, onset in sporadic diseases may originate from a gradually disrupted organellar homeostasis. Herein, endolysosomal abnormalities, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, and altered lipid metabolism are commonly observed in early preclinical stages of major NDs, including Parkinson's disease (PD) and Alzheimer's disease (AD). Among the multitude of underlying defective molecular mechanisms that have been suggested in the past decades, dysregulation of inter-organellar communication through the so-called membrane contact sites (MCSs) is becoming increasingly apparent. Although MCSs exist between almost every other type of subcellular organelle, to date, most focus has been put on defective communication between the ER and mitochondria in NDs, given these compartments are critical in neuronal survival. Contributions of other MCSs, notably those with endolysosomes and lipid droplets are emerging, supported as well by genetic studies, identifying genes functionally involved in lysosomal homeostasis. In this review, we summarize the molecular identity of the organelle interactome in yeast and mammalian cells, and critically evaluate the evidence supporting the contribution of disturbed MCSs to the general disrupted inter-organellar homeostasis in NDs, taking PD and AD as major examples.
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Affiliation(s)
- Stephanie Vrijsen
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, KU Leuven, Leuven, Belgium
| | - Céline Vrancx
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Mara Del Vecchio
- Laboratory of Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
| | - Johannes V. Swinnen
- Laboratory of Lipid Metabolism and Cancer, Department of Oncology, Leuven Cancer Institute (LKI), KU Leuven, Leuven, Belgium
- Johannes V. Swinnen
| | - Patrizia Agostinis
- Laboratory of Cell Death Research and Therapy, VIB-Center for Cancer Research, KU Leuven, Leuven, Belgium
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
- Patrizia Agostinis
| | - Joris Winderickx
- Laboratory of Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
- Joris Winderickx
| | - Peter Vangheluwe
- Laboratory of Cellular Transport Systems, Department of Cellular and Molecular Medicine, Katholieke Universiteit Leuven (KU Leuven), Leuven, Belgium
- Aligning Science Across Parkinson's (ASAP) Collaborative Research Network, KU Leuven, Leuven, Belgium
- Peter Vangheluwe
| | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research, KU Leuven, Leuven, Belgium
- Department of Neurosciences, KU Leuven, Leuven, Belgium
- *Correspondence: Wim Annaert
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30
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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.
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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;
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31
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Schneiter R, Choudhary V. Seipin collaborates with the ER membrane to control the sites of lipid droplet formation. Curr Opin Cell Biol 2022; 75:102070. [PMID: 35306312 PMCID: PMC7615794 DOI: 10.1016/j.ceb.2022.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 12/24/2022]
Abstract
Most cells store metabolic energy in lipid droplets (LDs). LDs are composed of a hydrophobic core, covered by a phospholipid monolayer, and functionalized by a specific set of proteins. Formation of LDs takes place in the endoplasmic reticulum (ER), where neutral lipid biosynthetic enzymes are located. Recent evidence indicate that this process is confined to specific ER subdomains, where proteins meet to initiate LD assembly. The lipodystrophy protein Seipin, is emerging as a major coordinator of LD biogenesis. Seipin forms a large oligomeric toroidal structure, which traps neutral lipids to promote LD nucleation. Here, we discuss the role of LD biogenesis factors that associate with Seipin to assemble functional LDs.
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Affiliation(s)
- Roger Schneiter
- University of Fribourg, Department of Biology, 1700, Fribourg, Switzerland.
| | - Vineet Choudhary
- All India Institute of Medical Sciences (AIIMS), Department of Biotechnology, New Delhi, 110029, India.
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32
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Seipin forms a flexible cage at lipid droplet formation sites. Nat Struct Mol Biol 2022; 29:194-202. [PMID: 35210614 PMCID: PMC8930772 DOI: 10.1038/s41594-021-00718-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 12/21/2021] [Indexed: 12/19/2022]
Abstract
Lipid droplets (LDs) form in the endoplasmic reticulum by phase separation of neutral lipids. This process is facilitated by the seipin protein complex, which consists of a ring of seipin monomers, with a yet unclear function. Here, we report a structure of S. cerevisiae seipin based on cryogenic-electron microscopy and structural modeling data. Seipin forms a decameric, cage-like structure with the lumenal domains forming a stable ring at the cage floor and transmembrane segments forming the cage sides and top. The transmembrane segments interact with adjacent monomers in two distinct, alternating conformations. These conformations result from changes in switch regions, located between the lumenal domains and the transmembrane segments, that are required for seipin function. Our data indicate a model for LD formation in which a closed seipin cage enables triacylglycerol phase separation and subsequently switches to an open conformation to allow LD growth and budding.
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33
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Xie K, Liu Y, Li X, Zhang H, Zhang S, Mak HY, Liu P. Dietary S. maltophilia induces supersized lipid droplets by enhancing lipogenesis and ER-LD contacts in C. elegans. Gut Microbes 2022; 14:2013762. [PMID: 35112996 PMCID: PMC8816401 DOI: 10.1080/19490976.2021.2013762] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Dietary and symbiotic bacteria can exert powerful influence on metazoan lipid metabolism. Recent studies have emerged that microbiota have a role in animal obesity and related health disorders, but the mechanisms by which bacteria influence lipid storage in their host are unknown. To reduce the complexity of the relationship between gut microbiota and the host, Caenorhabditis elegans (C. elegans) has been chosen as a model organism to study interspecies interaction. Here, we demonstrate that feeding C. elegans with an opportunistic pathogenic bacterium Stenotrophomonas maltophilia (S. maltophilia) retards growth and promotes excessive neutral lipid storage. Gene expression analysis reveals that dietary S. maltophilia induces a lipogenic transcriptional response that includes the SREBP ortholog SBP-1, and fatty acid desaturases FAT-6 and FAT-7. Live imaging and ultrastructural analysis suggest that excess neutral lipid is stored in greatly expanded lipid droplets (LDs), as a result of enhanced endoplasmic reticulum (ER)-LD interaction. We also report that loss of function mutations in dpy-9 in C. elegans confers resistance to S. maltophilia. Dietary S. maltophilia induces supersized LDs by enhancing lipogenesis and ER-LD contacts in C. elegans. This work delineates a new model for understanding microbial regulation of metazoan physiology.
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Affiliation(s)
- Kang Xie
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Yangli Liu
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Xixia Li
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China
| | - Shuyan Zhang
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Ho Yi Mak
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Pingsheng Liu
- National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China,University of Chinese Academy of Sciences, Beijing, China,CONTACT Pingsheng Liu National Laboratory of Biomacromolecules, Cas Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing100101, China
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34
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Olarte MJ, Swanson JMJ, Walther TC, Farese RV. The CYTOLD and ERTOLD pathways for lipid droplet-protein targeting. Trends Biochem Sci 2022; 47:39-51. [PMID: 34583871 PMCID: PMC8688270 DOI: 10.1016/j.tibs.2021.08.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 01/03/2023]
Abstract
Lipid droplets (LDs) are the main organelles for lipid storage, and their surfaces contain unique proteins with diverse functions, including those that facilitate the deposition and mobilization of LD lipids. Among organelles, LDs have an unusual structure with an organic, hydrophobic oil phase covered by a phospholipid monolayer. The unique properties of LD monolayer surfaces require proteins to localize to LDs by distinct mechanisms. Here we review the two pathways known to mediate direct LD protein localization: the CYTOLD pathway mediates protein targeting from the cytosol toLDs, and the ERTOLD pathway functions in protein targeting from the endoplasmic reticulum toLDs. We describe the emerging principles for each targeting pathway in animal cells and highlight open questions in the field.
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Affiliation(s)
- Maria-Jesus Olarte
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | | | - Tobias C Walther
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA.
| | - Robert V Farese
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02124, USA.
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35
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Mailler E, Guardia CM, Bai X, Jarnik M, Williamson CD, Li Y, Maio N, Golden A, Bonifacino JS. The autophagy protein ATG9A enables lipid mobilization from lipid droplets. Nat Commun 2021; 12:6750. [PMID: 34799570 PMCID: PMC8605025 DOI: 10.1038/s41467-021-26999-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 10/26/2021] [Indexed: 01/18/2023] Open
Abstract
The multispanning membrane protein ATG9A is a scramblase that flips phospholipids between the two membrane leaflets, thus contributing to the expansion of the phagophore membrane in the early stages of autophagy. Herein, we show that depletion of ATG9A does not only inhibit autophagy but also increases the size and/or number of lipid droplets in human cell lines and C. elegans. Moreover, ATG9A depletion blocks transfer of fatty acids from lipid droplets to mitochondria and, consequently, utilization of fatty acids in mitochondrial respiration. ATG9A localizes to vesicular-tubular clusters (VTCs) that are tightly associated with an ER subdomain enriched in another multispanning membrane scramblase, TMEM41B, and also in close proximity to phagophores, lipid droplets and mitochondria. These findings indicate that ATG9A plays a critical role in lipid mobilization from lipid droplets to autophagosomes and mitochondria, highlighting the importance of ATG9A in both autophagic and non-autophagic processes.
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Affiliation(s)
- Elodie Mailler
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Carlos M Guardia
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Xiaofei Bai
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Michal Jarnik
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Chad D Williamson
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Yan Li
- Proteomics Core Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Nunziata Maio
- Metals Biology and Molecular Medicine Group, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Juan S Bonifacino
- Neurosciences and Cellular and Structural Biology Division, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
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36
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Hello from the other side: Membrane contact of lipid droplets with other organelles and subsequent functional implications. Prog Lipid Res 2021; 85:101141. [PMID: 34793861 DOI: 10.1016/j.plipres.2021.101141] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/10/2021] [Accepted: 11/10/2021] [Indexed: 02/06/2023]
Abstract
Lipid droplets (LDs) are ubiquitous organelles that play crucial roles in response to physiological and environmental cues. The identification of several neutral lipid synthesizing and regulatory protein complexes have propelled significant advance on the mechanisms of LD biogenesis in the endoplasmic reticulum (ER). Increasing evidence suggests that distinct proteins and regulatory factors, which localize to membrane contact sites (MCS), are involved not only in interorganellar lipid exchange and transport, but also function in other important cellular processes, including autophagy, mitochondrial dynamics and inheritance, ion signaling and inter-regulation of these MCS. More and more tethers and molecular determinants are associated to MCS and to a diversity of cellular and pathophysiological processes, demonstrating the dynamics and importance of these junctions in health and disease. The conjugation of lipids with proteins in supramolecular complexes is known to be paramount for many biological processes, namely membrane biosynthesis, cell homeostasis, regulation of organelle division and biogenesis, and cell growth. Ultimately, this physical organization allows the contact sites to function as crucial metabolic hubs that control the occurrence of chemical reactions. This leads to biochemical and metabolite compartmentalization for the purposes of energetic efficiency and cellular homeostasis. In this review, we will focus on the structural and functional aspects of LD-organelle interactions and how they ensure signaling exchange and metabolites transfer between organelles.
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Lalioti V, Beznoussenko GV, Mironov AA, Sandoval IV. The E-Syt3 cleavage and traffic uncovers the primordial cisterna, a new organelle that mothers the lipid droplets in the adipocyte. Traffic 2021; 23:21-41. [PMID: 34693607 DOI: 10.1111/tra.12823] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 10/21/2021] [Indexed: 12/27/2022]
Abstract
Extended synaptotagmins are endoplasmic reticulum proteins consisting of an SMP domain and multiple C2 domains that bind phospholipids and Ca2+ . E-Syts create contact junctions between the ER and plasma membrane (PM) to facilitate the exchange of glycerophospholipids between the apposed membranes. We find in the differentiating adipocyte that the E-Syt3 carboxyl domain is cleaved by a multi-step mechanism that includes removing the C2C domain. Confocal and live-cell time-lapse studies show that truncated E-Syt3ΔC2C, as well as endogenous E-Syt3 and the coat protein PLIN1, target the LDs from an annular, single giant ER cisterna. Inhibition of the proteasome blocks the proteolytic cleavage of Esyt3 and E-Syt3ΔC2C and causes the E-Syt3ΔC2C retention in the giant cisterna. The Esyt3 and PLIN1 distributions and LDs biogenesis show that the primordial cisterna, as we call it, is the birth and nurturing site of LDs in the adipocyte. Isoproterenol-induced lipolysis results in loss of cytoplasmic LDs and reappearance of the primordial cisterna. Electron microscopy and 3D-electron tomography studies show that the primordial cisterna consists of a tightly packed network of varicose tubules with extensively blistered membranes. Rounds of homotypic fusions from nascent to mature LDs play a central role in LD growth. The knockdown of E-Syt3 inhibits LD biogenesis. The identification of the primordial cisterna, an organelle that substitutes the randomly scattered ER foci that mother the LDs in non-adipose cells, sets the stage for a better understanding of LD biogenesis in the adipocyte.
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Affiliation(s)
- Vasiliki Lalioti
- Centro de Biología Molecular Severo Ochoa, Department of Cell Biology and Immunology, Physiological and Pathological Processes, Madrid, Spain
| | - Galina V Beznoussenko
- Laboratory of Electron Microscopy, The FIRC Institute of Molecular Oncology, Milan, Italy
| | - Alexander A Mironov
- Laboratory of Electron Microscopy, The FIRC Institute of Molecular Oncology, Milan, Italy
| | - Ignacio V Sandoval
- Centro de Biología Molecular Severo Ochoa, Department of Cell Biology and Immunology, Physiological and Pathological Processes, Madrid, Spain
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38
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Klug YA, Deme JC, Corey RA, Renne MF, Stansfeld PJ, Lea SM, Carvalho P. Mechanism of lipid droplet formation by the yeast Sei1/Ldb16 Seipin complex. Nat Commun 2021; 12:5892. [PMID: 34625558 PMCID: PMC8501077 DOI: 10.1038/s41467-021-26162-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Accepted: 09/21/2021] [Indexed: 11/09/2022] Open
Abstract
Lipid droplets (LDs) are universal lipid storage organelles with a core of neutral lipids, such as triacylglycerols, surrounded by a phospholipid monolayer. This unique architecture is generated during LD biogenesis at endoplasmic reticulum (ER) sites marked by Seipin, a conserved membrane protein mutated in lipodystrophy. Here structural, biochemical and molecular dynamics simulation approaches reveal the mechanism of LD formation by the yeast Seipin Sei1 and its membrane partner Ldb16. We show that Sei1 luminal domain assembles a homooligomeric ring, which, in contrast to other Seipins, is unable to concentrate triacylglycerol. Instead, Sei1 positions Ldb16, which concentrates triacylglycerol within the Sei1 ring through critical hydroxyl residues. Triacylglycerol recruitment to the complex is further promoted by Sei1 transmembrane segments, which also control Ldb16 stability. Thus, we propose that LD assembly by the Sei1/Ldb16 complex, and likely other Seipins, requires sequential triacylglycerol-concentrating steps via distinct elements in the ER membrane and lumen.
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Affiliation(s)
- Yoel A Klug
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Justin C Deme
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Mike F Renne
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford, UK
- School of Life Sciences & Department of Chemistry, University of Warwick, Coventry, UK
| | - Susan M Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA.
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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Ferreira JV, Carvalho P. Pex30-like proteins function as adaptors at distinct ER membrane contact sites. J Cell Biol 2021; 220:212563. [PMID: 34402813 PMCID: PMC8374871 DOI: 10.1083/jcb.202103176] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/19/2021] [Accepted: 07/20/2021] [Indexed: 12/20/2022] Open
Abstract
Membrane lipids and proteins synthesized in the ER are used for de novo assembly of organelles, such as lipid droplets and peroxisomes. After assembly, the growth of these organelles is supported by ER-derived lipids transferred at membrane contact sites (MCSs). How ER sites for organelle biogenesis and lipid transfer are established and regulated is unclear. Here, we investigate how the ER membrane protein Pex30 and its family members Pex28, Pex29, Pex31, and Pex32 target and function at multiple MCSs. We show that different Pex30 complexes function at distinct ER domains and MCSs. Pex30 targets ER–peroxisome MCSs when bound to Pex28 and Pex32, organizes the nuclear–vacuolar junction when bound to Pex29, and promotes the biogenesis of lipid droplets independently of other family members. Importantly, the reticulon homology domain (RHD) mediates the assembly of the various Pex30 complexes. Given the role of RHD in membrane shaping, our findings offer a mechanistic link between MCS and regulation of membrane curvature.
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Affiliation(s)
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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40
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Romanauska A, Köhler A. Reprogrammed lipid metabolism protects inner nuclear membrane against unsaturated fat. Dev Cell 2021; 56:2562-2578.e3. [PMID: 34407429 PMCID: PMC8480995 DOI: 10.1016/j.devcel.2021.07.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 06/04/2021] [Accepted: 07/26/2021] [Indexed: 11/20/2022]
Abstract
The cell nucleus is surrounded by a double membrane. The lipid packing and viscosity of membranes is critical for their function and is tightly controlled by lipid saturation. Circuits regulating the lipid saturation of the outer nuclear membrane (ONM) and contiguous endoplasmic reticulum (ER) are known. However, how lipid saturation is controlled in the inner nuclear membrane (INM) has remained enigmatic. Using INM biosensors and targeted genetic manipulations, we show that increased lipid unsaturation causes a reprogramming of lipid storage metabolism across the nuclear envelope (NE). Cells induce lipid droplet (LD) formation specifically from the distant ONM/ER, whereas LD formation at the INM is suppressed. In doing so, unsaturated fatty acids are shifted away from the INM. We identify the transcription circuits that topologically reprogram LD synthesis and identify seipin and phosphatidic acid as critical effectors. Our study suggests a detoxification mechanism protecting the INM from excess lipid unsaturation. Biosensors detect lipid saturation dynamics of INM Increased lipid unsaturation induces LDs at ONM, but not at INM Opposing transcription circuits reprogram LD synthesis across the NE LDs detoxify unsaturated lipids to maintain INM integrity
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Affiliation(s)
- Anete Romanauska
- Max Perutz Labs, University of Vienna and Medical University of Vienna, Vienna Biocenter Campus (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria
| | - Alwin Köhler
- Max Perutz Labs, University of Vienna and Medical University of Vienna, Vienna Biocenter Campus (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria.
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41
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Pyc M, Gidda SK, Seay D, Esnay N, Kretzschmar FK, Cai Y, Doner NM, Greer MS, Hull JJ, Coulon D, Bréhélin C, Yurchenko O, de Vries J, Valerius O, Braus GH, Ischebeck T, Chapman KD, Dyer JM, Mullen RT. LDIP cooperates with SEIPIN and LDAP to facilitate lipid droplet biogenesis in Arabidopsis. THE PLANT CELL 2021; 33:3076-3103. [PMID: 34244767 PMCID: PMC8462815 DOI: 10.1093/plcell/koab179] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 06/26/2021] [Indexed: 05/19/2023]
Abstract
Cytoplasmic lipid droplets (LDs) are evolutionarily conserved organelles that store neutral lipids and play critical roles in plant growth, development, and stress responses. However, the molecular mechanisms underlying their biogenesis at the endoplasmic reticulum (ER) remain obscure. Here we show that a recently identified protein termed LD-associated protein [LDAP]-interacting protein (LDIP) works together with both endoplasmic reticulum-localized SEIPIN and the LD-coat protein LDAP to facilitate LD formation in Arabidopsis thaliana. Heterologous expression in insect cells demonstrated that LDAP is required for the targeting of LDIP to the LD surface, and both proteins are required for the production of normal numbers and sizes of LDs in plant cells. LDIP also interacts with SEIPIN via a conserved hydrophobic helix in SEIPIN and LDIP functions together with SEIPIN to modulate LD numbers and sizes in plants. Further, the co-expression of both proteins is required to restore normal LD production in SEIPIN-deficient yeast cells. These data, combined with the analogous function of LDIP to a mammalian protein called LD Assembly Factor 1, are discussed in the context of a new model for LD biogenesis in plant cells with evolutionary connections to LD biogenesis in other eukaryotes.
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Affiliation(s)
| | | | - Damien Seay
- U.S. Department of Agriculture, Agricultural Research Service, U.S. Arid-Land Agricultural Research Center, Maricopa, Arizona 85138, USA
| | - Nicolas Esnay
- BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, Texas 76203, USA
| | - Franziska K. Kretzschmar
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, 37077 Göttingen, Germany
| | | | - Nathan M. Doner
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | | | - J. Joe Hull
- U.S. Department of Agriculture, Agricultural Research Service, U.S. Arid-Land Agricultural Research Center, Maricopa, Arizona 85138, USA
| | - Denis Coulon
- Université de Bordeaux, Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, UMR5200, F-33140 Villenave d’Ornon, France
| | - Claire Bréhélin
- Université de Bordeaux, Centre National de la Recherche Scientifique, Laboratoire de Biogenèse Membranaire, UMR5200, F-33140 Villenave d’Ornon, France
| | | | - Jan de Vries
- Institute for Microbiology and Genetics, Göttingen Center for Molecular Biosciences and Campus Institute Data Science, Department of Applied Bioinformatics, University of Göttingen, 37077 Göttingen, Germany
| | - Oliver Valerius
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences, Department for Molecular Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany
| | - Gerhard H. Braus
- Institute for Microbiology and Genetics and Göttingen Center for Molecular Biosciences, Department for Molecular Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany
| | - Till Ischebeck
- Department of Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, 37077 Göttingen, Germany
| | - Kent D. Chapman
- BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, Texas 76203, USA
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42
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Renne MF, Hariri H. Lipid Droplet-Organelle Contact Sites as Hubs for Fatty Acid Metabolism, Trafficking, and Metabolic Channeling. Front Cell Dev Biol 2021; 9:726261. [PMID: 34595176 PMCID: PMC8477659 DOI: 10.3389/fcell.2021.726261] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/12/2021] [Indexed: 01/21/2023] Open
Abstract
Cells prepare for fluctuations in nutrient availability by storing energy in the form of neutral lipids in organelles called Lipid Droplets (LDs). Upon starvation, fatty acids (FAs) released from LDs are trafficked to different cellular compartments to be utilized for membrane biogenesis or as a source of energy. Despite the biochemical pathways being known in detail, the spatio-temporal regulation of FA synthesis, storage, release, and breakdown is not completely understood. Recent studies suggest that FA trafficking and metabolism are facilitated by inter-organelle contact sites that form between LDs and other cellular compartments such as the Endoplasmic Reticulum (ER), mitochondria, peroxisomes, and lysosomes. LD-LD contact sites are also sites where FAs are transferred in a directional manner to support LD growth and expansion. As the storage site of neutral lipids, LDs play a central role in FA homeostasis. In this mini review, we highlight the role of LD contact sites with other organelles in FA trafficking, channeling, and metabolism and discuss the implications for these pathways on cellular lipid and energy homeostasis.
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Affiliation(s)
- Mike F. Renne
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Hanaa Hariri
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
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43
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Cottier S, Schneiter R. Lipid droplets form a network interconnected by the endoplasmic reticulum through which their proteins equilibrate. J Cell Sci 2021; 135:271208. [PMID: 34373922 DOI: 10.1242/jcs.258819] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 07/03/2021] [Indexed: 01/13/2023] Open
Abstract
Lipid droplets (LDs) are globular intracellular structures dedicated to the storage of neutral lipids. They are closely associated with the endoplasmic reticulum (ER) and are delineated by a monolayer of phospholipids that is continuous with the cytoplasmic leaflet of the ER membrane. LDs contain a specific set of proteins, but how these proteins are targeted to the LD surface is not fully understood. Here, we devised a yeast mating-based microscopic readout to monitor the transfer of LD proteins upon zygote formation. The results of this analysis indicate that ER fusion between mating partners is required for transfer of LD proteins and that this transfer is continuous, bidirectional and affects most LDs simultaneously. These observations suggest that LDs do not fuse upon mating of yeast cells, but that they form a network that is interconnected through the ER membrane. Consistent with this, ER-localized LD proteins rapidly move onto LDs of a mating partner and this protein transfer is affected by seipin, a protein important for proper LD biogenesis and the functional connection of LDs with the ER membrane.
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Affiliation(s)
- Stéphanie Cottier
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
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44
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Molenaar MR, Yadav KK, Toulmay A, Wassenaar TA, Mari MC, Caillon L, Chorlay A, Lukmantara IE, Haaker MW, Wubbolts RW, Houweling M, Vaandrager AB, Prieur X, Reggiori F, Choudhary V, Yang H, Schneiter R, Thiam AR, Prinz WA, Helms JB. Retinyl esters form lipid droplets independently of triacylglycerol and seipin. J Cell Biol 2021; 220:212517. [PMID: 34323918 PMCID: PMC8327380 DOI: 10.1083/jcb.202011071] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 05/21/2021] [Accepted: 07/07/2021] [Indexed: 11/23/2022] Open
Abstract
Lipid droplets store neutral lipids, primarily triacylglycerol and steryl esters. Seipin plays a role in lipid droplet biogenesis and is thought to determine the site of lipid droplet biogenesis and the size of newly formed lipid droplets. Here we show a seipin-independent pathway of lipid droplet biogenesis. In silico and in vitro experiments reveal that retinyl esters have the intrinsic propensity to sequester and nucleate in lipid bilayers. Production of retinyl esters in mammalian and yeast cells that do not normally produce retinyl esters causes the formation of lipid droplets, even in a yeast strain that produces only retinyl esters and no other neutral lipids. Seipin does not determine the size or biogenesis site of lipid droplets composed of only retinyl esters or steryl esters. These findings indicate that the role of seipin in lipid droplet biogenesis depends on the type of neutral lipid stored in forming droplets.
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Affiliation(s)
- Martijn R Molenaar
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Kamlesh K Yadav
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Alexandre Toulmay
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Tsjerk A Wassenaar
- Groningen Biomolecular Sciences and Biotechnology Institute, Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Muriel C Mari
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Lucie Caillon
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - Aymeric Chorlay
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - Ivan E Lukmantara
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Maya W Haaker
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Richard W Wubbolts
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Martin Houweling
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Arie Bas Vaandrager
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
| | - Xavier Prieur
- Université de Nantes, Centre national de la recherche scientifique, Institut national de la santé et de la recherche médicale, l'institut du thorax, Nantes, France
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Vineet Choudhary
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Hongyuan Yang
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Abdou Rachid Thiam
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, Paris Sciences et Lettres Research University, Sorbonne Université, Université Pierre-et-Marie-Curie Université Paris 06, Université Paris Diderot, Centre national de la recherche scientifique, Paris, France
| | - William A Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - J Bernd Helms
- Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, Netherlands
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45
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Joshi AS, Ragusa JV, Prinz WA, Cohen S. Multiple C2 domain-containing transmembrane proteins promote lipid droplet biogenesis and growth at specialized endoplasmic reticulum subdomains. Mol Biol Cell 2021; 32:1147-1157. [PMID: 33826368 PMCID: PMC8351558 DOI: 10.1091/mbc.e20-09-0590] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 03/23/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022] Open
Abstract
Lipid droplets (LDs) are neutral lipid-containing organelles enclosed in a single monolayer of phospholipids. LD formation begins with the accumulation of neutral lipids within the bilayer of the endoplasmic reticulum (ER) membrane. It is not known how the sites of formation of nascent LDs in the ER membrane are determined. Here we show that multiple C2 domain-containing transmembrane proteins, MCTP1 and MCTP2, are at sites of LD formation in specialized ER subdomains. We show that the transmembrane domain (TMD) of these proteins is similar to a reticulon homology domain. Like reticulons, these proteins tubulate the ER membrane and favor highly curved regions of the ER. Our data indicate that the MCTP TMDs promote LD biogenesis, increasing LD number. MCTPs colocalize with seipin, a protein involved in LD biogenesis, but form more stable microdomains in the ER. The MCTP C2 domains bind charged lipids and regulate LD size, likely by mediating ER-LD contact sites. Together, our data indicate that MCTPs form microdomains within ER tubules that regulate LD biogenesis, size, and ER-LD contacts. Interestingly, MCTP punctae colocalized with other organelles as well, suggesting that these proteins may play a general role in linking tubular ER to organelle contact sites.
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Affiliation(s)
- Amit S. Joshi
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
- Department of Biochemistry, Cell and Molecular Biology, University of Tennessee, Knoxville, TN 37916
| | - Joey V. Ragusa
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - William A. Prinz
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20814
| | - Sarah Cohen
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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46
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Chartschenko E, Hugenroth M, Akhtar I, Droste A, Kolkhof P, Bohnert M, Beller M. CG32803 is the fly homolog of LDAF1 and influences lipid storage in vivo. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2021; 133:103512. [PMID: 33307187 DOI: 10.1016/j.ibmb.2020.103512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 11/05/2020] [Accepted: 11/29/2020] [Indexed: 06/12/2023]
Abstract
The Seipin protein is a conserved key component in the biogenesis of lipid droplets (LDs). Recently, a cooperation between human Seipin and the Lipid droplet assembly factor 1 (LDAF1) was described. LDAF1 physically interacts with Seipin and the holocomplex safeguards regular LD biogenesis. The function of LDAF1 proteins outside mammals is less clear. In yeast, the lipid droplet organization (LDO) proteins, which also cooperate with Seipin, are the putative homologs of LDAF1. While certain functional aspects are shared between the LDO and mammalian LDAF1 proteins, the relationship between the proteins is under debate. Here, we identify the Drosophila melanogaster protein CG32803, which we re-named to dmLDAF1, as an insect member of this protein family. dmLDAF1 decorates LDs in cultured cells and in vivo and the protein is linked to the fly and mouse Seipin proteins. Altering the dmLDAF1 abundance affects LD size, number and overall lipid storage amounts. Our results suggest that the LDAF1 proteins thus fulfill an evolutionarily conserved function in the biogenesis and biology of LDs.
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Affiliation(s)
- Eugenia Chartschenko
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany; Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany
| | - Marie Hugenroth
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, Münster, 48149, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, 48149, Germany
| | - Irfan Akhtar
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany; Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany
| | - Andrea Droste
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany; Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany
| | - Petra Kolkhof
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany; Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany
| | - Maria Bohnert
- Institute of Cell Dynamics and Imaging, University of Münster, Von-Esmarch-Str. 56, Münster, 48149, Germany; Cells in Motion Interfaculty Centre (CiM), University of Münster, Münster, 48149, Germany
| | - Mathias Beller
- Institute for Mathematical Modeling of Biological Systems, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany; Systems Biology of Lipid Metabolism, Heinrich Heine University Düsseldorf, Düsseldorf, 40225, Germany.
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47
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Khaddaj R, Mari M, Cottier S, Reggiori F, Schneiter R. The surface of lipid droplets constitutes a barrier for endoplasmic reticulum-resident integral membrane proteins. J Cell Sci 2021; 135:268334. [PMID: 34028531 DOI: 10.1242/jcs.256206] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 04/14/2021] [Indexed: 12/12/2022] Open
Abstract
Lipid droplets (LDs) are globular subcellular structures that store neutral lipids. LDs are closely associated with the endoplasmic reticulum (ER) and are limited by a phospholipid monolayer harboring a specific set of proteins. Most of these proteins associate with LDs through either an amphipathic helix or a membrane-embedded hairpin motif. Here, we address the question of whether integral membrane proteins can localize to the surface of LDs. To test this, we fused perilipin 3 (PLIN3), a mammalian LD-targeted protein, to ER-resident proteins. The resulting fusion proteins localized to the periphery of LDs in both yeast and mammalian cells. This peripheral LD localization of the fusion proteins, however, was due to a redistribution of the ER around LDs, as revealed by bimolecular fluorescence complementation between ER- and LD-localized partners. A LD-tethering function of PLIN3-containing membrane proteins was confirmed by fusing PLIN3 to the cytoplasmic domain of an outer mitochondrial membrane protein, OM14. Expression of OM14-PLIN3 induced a close apposition between LDs and mitochondria. These data indicate that the ER-LD junction constitutes a barrier for ER-resident integral membrane proteins.
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Affiliation(s)
- Rasha Khaddaj
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Muriel Mari
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Stéphanie Cottier
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
| | - Fulvio Reggiori
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Roger Schneiter
- Department of Biology, University of Fribourg, Chemin du Musée 10, 1700 Fribourg, Switzerland
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48
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Sołtysik K, Ohsaki Y, Tatematsu T, Cheng J, Maeda A, Morita SY, Fujimoto T. Nuclear lipid droplets form in the inner nuclear membrane in a seipin-independent manner. J Cell Biol 2021; 220:211592. [PMID: 33315072 PMCID: PMC7737703 DOI: 10.1083/jcb.202005026] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 09/25/2020] [Accepted: 11/11/2020] [Indexed: 01/09/2023] Open
Abstract
Nuclear lipid droplets (LDs) in hepatocytes are derived from precursors of very-low-density lipoprotein in the ER lumen, but it is not known how cells lacking the lipoprotein secretory function form nuclear LDs. Here, we show that the inner nuclear membrane (INM) of U2OS cells harbors triglyceride synthesis enzymes, including ACSL3, AGPAT2, GPAT3/GPAT4, and DGAT1/DGAT2, and generates nuclear LDs in situ. mTOR inhibition increases nuclear LDs by inducing the nuclear translocation of lipin-1 phosphatidic acid (PA) phosphatase. Seipin, a protein essential for normal cytoplasmic LD formation in the ER, is absent in the INM. Knockdown of seipin increases nuclear LDs and PA in the nucleus, whereas seipin overexpression decreases these. Seipin knockdown also up-regulates lipin-1β expression, and lipin-1 knockdown decreases the effect of seipin knockdown on nuclear LDs without affecting PA redistribution. These results indicate that seipin is not directly involved in nuclear LD formation but instead restrains it by affecting lipin-1 expression and intracellular PA distribution.
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Affiliation(s)
- Kamil Sołtysik
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yuki Ohsaki
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tsuyako Tatematsu
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Jinglei Cheng
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Asami Maeda
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Shin-Ya Morita
- Department of Pharmacy, Shiga University of Medical Science Hospital, Otsu City, Shiga, Japan
| | - Toyoshi Fujimoto
- Laboratory of Molecular Cell Biology, Research Institute for Diseases of Old Age, Juntendo University Graduate School of Medicine, Tokyo, Japan
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49
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Guéguen N, Le Moigne D, Amato A, Salvaing J, Maréchal E. Lipid Droplets in Unicellular Photosynthetic Stramenopiles. FRONTIERS IN PLANT SCIENCE 2021; 12:639276. [PMID: 33968100 PMCID: PMC8100218 DOI: 10.3389/fpls.2021.639276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
The Heterokonta or Stramenopile phylum comprises clades of unicellular photosynthetic species, which are promising for a broad range of biotechnological applications, based on their capacity to capture atmospheric CO2 via photosynthesis and produce biomolecules of interest. These molecules include triacylglycerol (TAG) loaded inside specific cytosolic bodies, called the lipid droplets (LDs). Understanding TAG production and LD biogenesis and function in photosynthetic stramenopiles is therefore essential, and is mostly based on the study of a few emerging models, such as the pennate diatom Phaeodactylum tricornutum and eustigmatophytes, such as Nannochloropsis and Microchloropsis species. The biogenesis of cytosolic LD usually occurs at the level of the endoplasmic reticulum. However, stramenopile cells contain a complex plastid deriving from a secondary endosymbiosis, limited by four membranes, the outermost one being connected to the endomembrane system. Recent cell imaging and proteomic studies suggest that at least some cytosolic LDs might be associated to the surface of the complex plastid, via still uncharacterized contact sites. The carbon length and number of double bonds of the acyl groups contained in the TAG molecules depend on their origin. De novo synthesis produces long-chain saturated or monounsaturated fatty acids (SFA, MUFA), whereas subsequent maturation processes lead to very long-chain polyunsaturated FA (VLC-PUFA). TAG composition in SFA, MUFA, and VLC-PUFA reflects therefore the metabolic context that gave rise to the formation of the LD, either via an early partitioning of carbon following FA de novo synthesis and/or a recycling of FA from membrane lipids, e.g., plastid galactolipids or endomembrane phosphor- or betaine lipids. In this review, we address the relationship between cytosolic LDs and the complex membrane compartmentalization within stramenopile cells, the metabolic routes leading to TAG accumulation, and the physiological conditions that trigger LD production, in response to various environmental factors.
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50
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Chen F, Yan B, Ren J, Lyu R, Wu Y, Guo Y, Li D, Zhang H, Hu J. FIT2 organizes lipid droplet biogenesis with ER tubule-forming proteins and septins. J Cell Biol 2021; 220:211999. [PMID: 33861319 PMCID: PMC8056755 DOI: 10.1083/jcb.201907183] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/29/2020] [Accepted: 02/09/2021] [Indexed: 12/20/2022] Open
Abstract
Lipid droplets (LDs) are critical for lipid storage and energy metabolism. LDs form in the endoplasmic reticulum (ER). However, the molecular basis for LD biogenesis remains elusive. Here, we show that fat storage–inducing transmembrane protein 2 (FIT2) interacts with ER tubule-forming proteins Rtn4 and REEP5. The association is mainly transmembrane domain based and stimulated by oleic acid. Depletion of ER tubule-forming proteins decreases the number and size of LDs in cells and Caenorhabditis elegans, mimicking loss of FIT2. Through cytosolic loops, FIT2 binds to cytoskeletal protein septin 7, an interaction that is also required for normal LD biogenesis. Depletion of ER tubule-forming proteins or septins delays nascent LD formation. In addition, FIT2-interacting proteins are up-regulated during adipocyte differentiation, and ER tubule-forming proteins, septin 7, and FIT2 are transiently enriched at LD formation sites. Thus, FIT2-mediated nascent LD biogenesis is facilitated by ER tubule-forming proteins and septins.
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Affiliation(s)
- Fang Chen
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Bing Yan
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jie Ren
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Rui Lyu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yanfang Wu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yuting Guo
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Dong Li
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Hong Zhang
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Junjie Hu
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
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