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Jang E, Lee M, Yoon SY, Lee SS, Park J, Jin MS, Eom SH, Lee C, Jun Y. Yeast lunapark regulates the formation of trans-Sey1p complexes for homotypic ER membrane fusion. iScience 2023; 26:108386. [PMID: 38025788 PMCID: PMC10679814 DOI: 10.1016/j.isci.2023.108386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/24/2023] [Accepted: 10/30/2023] [Indexed: 12/01/2023] Open
Abstract
The endoplasmic reticulum (ER) consists of the nuclear envelope and a connected peripheral network of tubules and interspersed sheets. The structure of ER tubules is generated and maintained by various proteins, including reticulons, DP1/Yop1p, atlastins, and lunapark. Reticulons and DP1/Yop1p stabilize the high membrane curvature of ER tubules, and atlastins mediate homotypic membrane fusion between ER tubules; however, the exact role of lunapark remains poorly characterized. Here, using isolated yeast ER microsomes and reconstituted proteoliposomes, we directly examined the function of the yeast lunapark Lnp1p for yeast atlastin Sey1p-mediated ER fusion and found that Lnp1p inhibits Sey1p-driven membrane fusion. Furthermore, by using a newly developed assay for monitoring trans-Sey1p complex assembly, a prerequisite for ER fusion, we found that assembly of trans-Sey1p complexes was increased by the deletion of LNP1 and decreased by the overexpression of Lnp1p, indicating that Lnp1p inhibits Sey1p-mediated fusion by interfering with assembly of trans-Sey1p complexes.
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Affiliation(s)
- Eunhong Jang
- School of Life Sciences, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Miriam Lee
- School of Life Sciences, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - So Young Yoon
- School of Life Sciences, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Sang Soo Lee
- School of Life Sciences, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Jongseo Park
- School of Life Sciences, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Mi Sun Jin
- School of Life Sciences, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Soo Hyun Eom
- School of Life Sciences, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
| | - Changwook Lee
- Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Youngsoo Jun
- School of Life Sciences, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
- Cell Logistics Research Center, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju 61005, Republic of Korea
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Liu S, Yang B, Hou Y, Cui K, Yang X, Li X, Chen L, Liu S, Zhang Z, Jia Y, Xie Y, Xue Y, Li X, Yan B, Wu C, Deng W, Qi J, Lu D, Gao GF, Wang P, Shang G. The mechanism of STING autoinhibition and activation. Mol Cell 2023; 83:1502-1518.e10. [PMID: 37086726 DOI: 10.1016/j.molcel.2023.03.029] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/21/2022] [Accepted: 03/30/2023] [Indexed: 04/24/2023]
Abstract
2',3'-cGAMP, produced by the DNA sensor cGAS, activates stimulator of interferon genes (STING) and triggers immune response during infection. Tremendous effort has been placed on unraveling the mechanism of STING activation. However, little is known about STING inhibition. Here, we found that apo-STING exhibits a bilayer with head-to-head as well as side-by-side packing, mediated by its ligand-binding domain (LBD). This type of assembly holds two endoplasmic reticulum (ER) membranes together not only to prevent STING ER exit but also to eliminate the recruitment of TBK1, representing the autoinhibited state of STING. Additionally, we obtained the filament structure of the STING/2',3'-cGAMP complex, which adopts a bent monolayer assembly mediated by LBD and transmembrane domain (TMD). The active, curved STING polymer could deform ER membrane to support its ER exit and anterograde transportation. Our data together provide a panoramic vision regarding STING autoinhibition and activation, which adds substantially to current understanding of the cGAS-STING pathway.
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Affiliation(s)
- Sheng Liu
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Cryo-EM Center, Southern University of Science and Technology, Shenzhen 518055, China
| | - Bo Yang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; College of Life Sciences, Shanxi Agricultural University, Taiyuan 030031, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Yingxiang Hou
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; The Key Laboratory of Medical Molecular Cell Biology of Shanxi Province, Institutes of Biomedical Sciences, Shanxi University, Taiyuan 030006, China
| | - Kaige Cui
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Xiaozhu Yang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Xiaoxiong Li
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Lianwan Chen
- National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shichao Liu
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Zhichao Zhang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Yuanyuan Jia
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Yufeng Xie
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Department of Basic Medical Sciences, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Ying Xue
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China
| | - Xiaomei Li
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China
| | - Bingxue Yan
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China
| | - Changxin Wu
- The Key Laboratory of Medical Molecular Cell Biology of Shanxi Province, Institutes of Biomedical Sciences, Shanxi University, Taiyuan 030006, China
| | - Wen Deng
- College of Veterinary Medicine, Northwest A&F University, Yangling 712100, China
| | - Jianxun Qi
- CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; Beijing Life Science Academy, Beijing 102209, China
| | - Defen Lu
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; College of Life Sciences, Shanxi Agricultural University, Taiyuan 030031, China.
| | - George F Gao
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
| | - Peiyi Wang
- Cryo-EM Center, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Guijun Shang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China; College of Life Sciences, Shanxi Agricultural University, Taiyuan 030031, China; Shanxi Provincial Key Laboratory for Major Infectious Disease Response, Taiyuan 030012, China.
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Wang P, Duckney P, Gao E, Hussey PJ, Kriechbaumer V, Li C, Zang J, Zhang T. Keep in contact: multiple roles of endoplasmic reticulum-membrane contact sites and the organelle interaction network in plants. THE NEW PHYTOLOGIST 2023; 238:482-499. [PMID: 36651025 DOI: 10.1111/nph.18745] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Functional regulation and structural maintenance of the different organelles in plants contribute directly to plant development, reproduction and stress responses. To ensure these activities take place effectively, cells have evolved an interconnected network amongst various subcellular compartments, regulating rapid signal transduction and the exchange of biomaterial. Many proteins that regulate membrane connections have recently been identified in plants, and this is the first step in elucidating both the mechanism and function of these connections. Amongst all organelles, the endoplasmic reticulum is the key structure, which likely links most of the different subcellular compartments through membrane contact sites (MCS) and the ER-PM contact sites (EPCS) have been the most intensely studied in plants. However, the molecular composition and function of plant MCS are being found to be different from other eukaryotic systems. In this article, we will summarise the most recent advances in this field and discuss the mechanism and biological relevance of these essential links in plants.
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Affiliation(s)
- Pengwei Wang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
- Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Patrick Duckney
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - Erlin Gao
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
- Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Patrick J Hussey
- Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK
| | - Verena Kriechbaumer
- Endomembrane Structure and Function Research Group, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Chengyang Li
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
- Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Jingze Zang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
- Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Tong Zhang
- National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops, College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China
- Hubei Hongshan Laboratory, Wuhan, 430070, China
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Nuclear Envelope Proteins Modulating the Heterochromatin Formation and Functions in Fission Yeast. Cells 2020; 9:cells9081908. [PMID: 32824370 PMCID: PMC7464478 DOI: 10.3390/cells9081908] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/14/2020] [Accepted: 08/15/2020] [Indexed: 12/16/2022] Open
Abstract
The nuclear envelope (NE) consists of the inner and outer nuclear membranes (INM and ONM), and the nuclear pore complex (NPC), which penetrates the double membrane. ONM continues with the endoplasmic reticulum (ER). INM and NPC can interact with chromatin to regulate the genetic activities of the chromosome. Studies in the fission yeast Schizosaccharomyces pombe have contributed to understanding the molecular mechanisms underlying heterochromatin formation by the RNAi-mediated and histone deacetylase machineries. Recent studies have demonstrated that NE proteins modulate heterochromatin formation and functions through interactions with heterochromatic regions, including the pericentromeric and the sub-telomeric regions. In this review, we first introduce the molecular mechanisms underlying the heterochromatin formation and functions in fission yeast, and then summarize the NE proteins that play a role in anchoring heterochromatic regions and in modulating heterochromatin formation and functions, highlighting roles for a conserved INM protein, Lem2.
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5
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Shi X, Hai L, Govindasamy K, Gao J, Coppens I, Hu J, Wang Q, Bhanot P. A Plasmodium homolog of ER tubule-forming proteins is required for parasite virulence. Mol Microbiol 2020; 114:454-467. [PMID: 32432369 DOI: 10.1111/mmi.14526] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 01/27/2023]
Abstract
Reticulon and REEP family of proteins stabilize the high curvature of endoplasmic reticulum (ER) tubules. Plasmodium berghei Yop1 (PbYop1) is a REEP5 homolog in Plasmodium. Here, we characterize its function using a gene-knockout (Pbyop1∆). Pbyop1∆ asexual stage parasites display abnormal ER architecture and an enlarged digestive vacuole. The erythrocytic cycle of Pbyop1∆ parasites is severely attenuated and the incidence of experimental cerebral malaria is significantly decreased in Pbyop1∆-infected mice. Pbyop1∆ sporozoites have reduced speed, are slower to invade host cells but give rise to equal numbers of infected HepG2 cells, as WT sporozoites. We propose that PbYOP1's disruption may lead to defects in trafficking and secretion of a subset of proteins required for parasite development and invasion of erythrocytes. Furthermore, the maintenance of ER morphology in different parasite stages is likely to depend on different proteins.
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Affiliation(s)
- Xiaoyu Shi
- Department of Immunology, School of Basic Medical Sciences, Tianjin Key Laboratory of Cellular and Molecular Immunology, Key Laboratory of Immune Microenvironment and Diseases of Educational Ministry of China, Tianjin Medical University, Tianjin, China
| | - Lei Hai
- Department of Immunology, School of Basic Medical Sciences, Tianjin Key Laboratory of Cellular and Molecular Immunology, Key Laboratory of Immune Microenvironment and Diseases of Educational Ministry of China, Tianjin Medical University, Tianjin, China
| | - Kavitha Govindasamy
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Jian Gao
- Department of Immunology, School of Basic Medical Sciences, Tianjin Key Laboratory of Cellular and Molecular Immunology, Key Laboratory of Immune Microenvironment and Diseases of Educational Ministry of China, Tianjin Medical University, Tianjin, China
| | - Isabelle Coppens
- Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
| | - Junjie Hu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Qian Wang
- Department of Immunology, School of Basic Medical Sciences, Tianjin Key Laboratory of Cellular and Molecular Immunology, Key Laboratory of Immune Microenvironment and Diseases of Educational Ministry of China, Tianjin Medical University, Tianjin, China.,National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Purnima Bhanot
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ, USA
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6
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Hirano Y, Kinugasa Y, Osakada H, Shindo T, Kubota Y, Shibata S, Haraguchi T, Hiraoka Y. Lem2 and Lnp1 maintain the membrane boundary between the nuclear envelope and endoplasmic reticulum. Commun Biol 2020; 3:276. [PMID: 32483293 PMCID: PMC7264229 DOI: 10.1038/s42003-020-0999-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 05/11/2020] [Indexed: 01/09/2023] Open
Abstract
The nuclear envelope (NE) continues to the endoplasmic reticulum (ER). Proper partitioning of NE and ER is crucial for cellular activity, but the key factors maintaining the boundary between NE and ER remain to be elucidated. Here we show that the conserved membrane proteins Lem2 and Lnp1 cooperatively play a crucial role in maintaining the NE-ER membrane boundary in fission yeast Schizosaccharomyces pombe. Cells lacking both Lem2 and Lnp1 caused severe growth defects associated with aberrant expansion of the NE/ER membranes, abnormal leakage of nuclear proteins, and abnormal formation of vacuolar-like structures in the nucleus. Overexpression of the ER membrane protein Apq12 rescued the growth defect associated with membrane disorder caused by the loss of Lem2 and Lnp1. Genetic analysis showed that Apq12 had overlapping functions with Lnp1. We propose that a membrane protein network with Lem2 and Lnp1 acts as a critical factor to maintain the NE-ER boundary.
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Affiliation(s)
- Yasuhiro Hirano
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.
| | - Yasuha Kinugasa
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
- Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, 734-8553, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan
| | - Tomoko Shindo
- Electron Microscope Laboratory, Keio University School of Medicine, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Yoshino Kubota
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
| | - Shinsuke Shibata
- Electron Microscope Laboratory, Keio University School of Medicine, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, Suita, 565-0871, Japan.
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, 651-2492, Japan.
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7
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Wang N, Rapoport TA. Reconstituting the reticular ER network - mechanistic implications and open questions. J Cell Sci 2019; 132:132/4/jcs227611. [PMID: 30670475 DOI: 10.1242/jcs.227611] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The endoplasmic reticulum (ER) is a major membrane-bound organelle in all eukaryotic cells. This organelle comprises morphologically distinct domains, including the nuclear envelope and peripheral sheets and tubules. The tubules are connected by three-way junctions into a network. Several membrane proteins have been implicated in network formation; curvature-stabilizing proteins generate the tubules themselves, and membrane-anchored GTPases fuse tubules into a network. Recent experiments have shown that a tubular network can be formed with reconstituted proteoliposomes containing the yeast membrane-fusing GTPase Sey1 and a curvature-stabilizing protein of either the reticulon or REEP protein families. The network forms in the presence of GTP and is rapidly disassembled when GTP hydrolysis of Sey1 is inhibited, indicating that continuous membrane fusion is required for its maintenance. Atlastin, the ortholog of Sey1 in metazoans, forms a network on its own, serving both as a fusion and curvature-stabilizing protein. These results show that the reticular ER can be generated by a surprisingly small set of proteins, and represents an energy-dependent steady state between formation and disassembly. Models for the molecular mechanism by which curvature-stabilizing proteins cooperate with fusion GTPases to form a reticular network have been proposed, but many aspects remain speculative, including the function of additional proteins, such as the lunapark protein, and the mechanism by which the ER interacts with the cytoskeleton. How the nuclear envelope and peripheral ER sheets are formed remain major unresolved questions in the field. Here, we review reconstitution experiments with purified curvature-stabilizing proteins and fusion GTPases, discuss mechanistic implications and point out open questions.
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Affiliation(s)
- Ning Wang
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115, USA
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Ave, Boston, MA 02115, USA
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Reciprocal regulation between lunapark and atlastin facilitates ER three-way junction formation. Protein Cell 2018; 10:510-525. [PMID: 30498943 PMCID: PMC6588657 DOI: 10.1007/s13238-018-0595-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 10/23/2018] [Indexed: 11/12/2022] Open
Abstract
Three-way junctions are characteristic structures of the tubular endoplasmic reticulum (ER) network. Junctions are formed through atlastin (ATL)-mediated membrane fusion and stabilized by lunapark (Lnp). However, how Lnp is preferentially enriched at three-way junctions remains elusive. Here, we showed that Lnp loses its junction localization when ATLs are deleted. Reintroduction of ATL1 R77A and ATL3, which have been shown to cluster at the junctions, but not wild-type ATL1, relocates Lnp to the junctions. Mutations in the N-myristoylation site or hydrophobic residues in the coiled coil (CC1) of Lnp N-terminus (NT) cause mis-targeting of Lnp. Conversely, deletion of the lunapark motif in the C-terminal zinc finger domain, which affects the homo-oligomerization of Lnp, does not alter its localization. Purified Lnp-NT attaches to the membrane in a myristoylation-dependent manner. The mutation of hydrophobic residues in CC1 does not affect membrane association, but compromises ATL interactions. In addition, Lnp-NT inhibits ATL-mediated vesicle fusion in vitro. These results suggest that CC1 in Lnp-NT contacts junction-enriched ATLs for proper localization; subsequently, further ATL activity is limited by Lnp after the junction is formed. The proposed mechanism ensures coordinated actions of ATL and Lnp in generating and maintaining three-way junctions.
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Li Q, Han X. Self-Assembled Rough Endoplasmic Reticulum-Like Proto-Organelles. iScience 2018; 8:138-147. [PMID: 30312864 PMCID: PMC6180236 DOI: 10.1016/j.isci.2018.09.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 09/18/2018] [Accepted: 09/21/2018] [Indexed: 11/22/2022] Open
Abstract
Nature has evolved elaborate, dynamic organelle morphologies for optimal organelle functions. Among them, cisternae stacks are the universal structure for most organelles. However, compared with the well-studied spherical cell/organelle membrane mimic, the fabrication of the ubiquitously present cisternal organelle-like membrane structures for organelle mimic remains a challenging task. Herein, rough endoplasmic reticulum (RER)-like helicoidal cisternae stacks were assembled to mimic the enzyme crowded environment in spatially confined RER cisternae. RER-like single helicoid, multiple helicoids, and secondary helix are all observed. Membrane electrostatics drives their formation and controls the percentages, which indicates the possible role of membrane electrostatics in RER shaping. The organelle-like cisternae stacks can reversibly expand and compress, which provides modulated crowded or de-crowded enzyme environment for biochemical reactions. This work provides advanced membrane models, and novel mechanisms for organelle shaping and helicoids formation, and holds great potential in biomimetics, cell biology, and advanced materials design.
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Affiliation(s)
- Qingchuan Li
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 West Da-Zhi Street, Harbin 150001, China
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 West Da-Zhi Street, Harbin 150001, China.
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10
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Breuss MW, Nguyen A, Song Q, Nguyen T, Stanley V, James KN, Musaev D, Chai G, Wirth SA, Anzenberg P, George RD, Johansen A, Ali S, Zia-Ur-Rehman M, Sultan T, Zaki MS, Gleeson JG. Mutations in LNPK, Encoding the Endoplasmic Reticulum Junction Stabilizer Lunapark, Cause a Recessive Neurodevelopmental Syndrome. Am J Hum Genet 2018; 103:296-304. [PMID: 30032983 PMCID: PMC6080764 DOI: 10.1016/j.ajhg.2018.06.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/27/2018] [Indexed: 11/16/2022] Open
Abstract
The dynamic shape of the endoplasmic reticulum (ER) is a reflection of its wide variety of critical cell biological functions. Consequently, perturbation of ER-shaping proteins can cause a range of human phenotypes. Here, we describe three affected children (from two consanguineous families) who carry homozygous loss-of-function mutations in LNPK (previously known as KIAA1715); this gene encodes lunapark, which is proposed to serve as a curvature-stabilizing protein within tubular three-way junctions of the ER. All individuals presented with severe psychomotor delay, intellectual disability, hypotonia, epilepsy, and corpus callosum hypoplasia, and two of three showed mild cerebellar hypoplasia and atrophy. Consistent with a proposed role in neurodevelopmental disease, LNPK was expressed during brain development in humans and mice and was present in neurite-like processes in differentiating human neural progenitor cells. Affected cells showed the absence of full-length lunapark, aberrant ER structures, and increased luminal mass density. Together, our results implicate the ER junction stabilizer lunapark in establishing the corpus callosum.
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Affiliation(s)
- Martin W Breuss
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - An Nguyen
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Qiong Song
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Thai Nguyen
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Valentina Stanley
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Kiely N James
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Damir Musaev
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Guoliang Chai
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Sara A Wirth
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Paula Anzenberg
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Renee D George
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Anide Johansen
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA
| | - Shaila Ali
- Department of Pediatric Neurology, Children's Hospital and Institute of Child Health, Lahore 54000, Pakistan
| | - Muhammad Zia-Ur-Rehman
- Department of Pediatric Neurology, Children's Hospital and Institute of Child Health, Lahore 54000, Pakistan
| | - Tipu Sultan
- Department of Pediatric Neurology, Children's Hospital and Institute of Child Health, Lahore 54000, Pakistan
| | - Maha S Zaki
- Clinical Genetics Department, Human Genetics and Genome Research Division, National Research Centre, Cairo 12311, Egypt
| | - Joseph G Gleeson
- Department of Neurosciences, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093, USA; Rady Children's Institute for Genomic Medicine, San Diego, CA 92025, USA.
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11
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Li Q, Han X. Self-Assembled "Breathing" Grana-Like Cisternae Stacks. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1707482. [PMID: 29707837 DOI: 10.1002/adma.201707482] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 02/12/2018] [Indexed: 06/08/2023]
Abstract
Membranes in cells display elaborate, dynamic morphologies intimately tied to defined cellular functions. Cisternae stacks are a common membrane morphology in cells widely found in organelles. However, compared with the well-studied spherical cell membrane mimics, cisternae stacks as organelle membrane mimics are greatly neglected because of the difficulty of fabricating this unique structure. Herein, the grana-like cisternae stacks are assembled via the reorganization of stacked microsized bicelles to mimic grana functions. The cisternae stacks are connected by fusion regions between adjacent cisternae. The number of cisternae can be controlled from ≈4 to 15 by the variation of ethanol volume percentage. Under the stimulation of solvent or negatively charged nanoparticles, the cisternae stacks can reversibly compress and expand, similar to the "breathing" property of natural grana. During the "breathing" process, nanoparticles are reversibly captured and released. Frequency resonance energy transfer is realized on the cisternae stacks trapped with two kinds of quantum dots. The cisternae stacks provide advanced membrane model for cell biotechnology, and clues for the shaping of organelles composed of cisternae. The ability of the cisternae stacks to capture materials enables them to possibly be applied in biomimetics and the design of advanced functional materials.
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Affiliation(s)
- Qingchuan Li
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 West Da-Zhi Street, Harbin, 150001, China
| | - Xiaojun Han
- State Key Laboratory of Urban Water Resource and Environment, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, 92 West Da-Zhi Street, Harbin, 150001, China
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