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Fernández-Jiménez N, Martinez-Garcia M, Varas J, Gil-Dones F, Santos JL, Pradillo M. The scaffold nucleoporins SAR1 and SAR3 are essential for proper meiotic progression in Arabidopsis thaliana. Front Cell Dev Biol 2023; 11:1285695. [PMID: 38111849 PMCID: PMC10725928 DOI: 10.3389/fcell.2023.1285695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 11/21/2023] [Indexed: 12/20/2023] Open
Abstract
Nuclear Pore Complexes (NPCs) are embedded in the nuclear envelope (NE), regulating macromolecule transport and physically interacting with chromatin. The NE undergoes dramatic breakdown and reformation during plant cell division. In addition, this structure has a specific meiotic function, anchoring and positioning telomeres to facilitate the pairing of homologous chromosomes. To elucidate a possible function of the structural components of the NPCs in meiosis, we have characterized several Arabidopsis lines with mutations in genes encoding nucleoporins belonging to the outer ring complex. Plants defective for either SUPPRESSOR OF AUXIN RESISTANCE1 (SAR1, also called NUP160) or SAR3 (NUP96) present condensation abnormalities and SPO11-dependent chromosome fragmentation in a fraction of meiocytes, which is increased in the double mutant sar1 sar3. We also observed these meiotic defects in mutants deficient in the outer ring complex protein HOS1, but not in mutants affected in other components of this complex. Furthermore, our findings may suggest defects in the structure of NPCs in sar1 and a potential link between the meiotic role of this nucleoporin and a component of the RUBylation pathway. These results provide the first insights in plants into the role of nucleoporins in meiotic chromosome behavior.
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Affiliation(s)
- Nadia Fernández-Jiménez
- Department of Genetics, Physiology and Microbiology, Faculty of Biological Sciences, Universidad Complutense de Madrid, Madrid, Spain
| | - Marina Martinez-Garcia
- Department of Biotechnology-Plant Biology, School of Agricultural, Food and Biosystems Engineering, Universidad Politécnica de Madrid, Madrid, Spain
| | | | - Félix Gil-Dones
- Department of Genetics, Physiology and Microbiology, Faculty of Biological Sciences, Universidad Complutense de Madrid, Madrid, Spain
| | - Juan Luis Santos
- Department of Genetics, Physiology and Microbiology, Faculty of Biological Sciences, Universidad Complutense de Madrid, Madrid, Spain
| | - Mónica Pradillo
- Department of Genetics, Physiology and Microbiology, Faculty of Biological Sciences, Universidad Complutense de Madrid, Madrid, Spain
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2
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Bravo-Plaza I, Hernández-González M, Peñalva MÁ. Comment on Dimou et al. Profile of Membrane Cargo Trafficking Proteins and Transporters Expressed under N Source Derepressing Conditions in Aspergillus nidulans. J. Fungi 2021, 7, 560. J Fungi (Basel) 2021; 7:jof7121037. [PMID: 34947019 PMCID: PMC8703528 DOI: 10.3390/jof7121037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 11/10/2021] [Accepted: 11/25/2021] [Indexed: 01/02/2023] Open
Abstract
Contrary to the opinion recently offered by Dimou et al., our previously published biochemical, subcellular and genetic data supported our contention that AN11127 corresponds to the A. nidulans gene encoding Sec12, which is the guanine nucleotide exchange factor (GEF) specific for SAR1. We add here additional bioinformatics evidence that fully disprove the otherwise negative evidence reported by Dimou et al., highlighting the dangers associated with the lax interpretation of genomic data. On the positive side, we establish guidelines for the identification of this key secretory gene in other species of Ascomycota and Basidiomycota, including species of medical and applied interest.
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Affiliation(s)
- Ignacio Bravo-Plaza
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28049 Madrid, Spain;
| | | | - Miguel Á. Peñalva
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, Ramiro de Maeztu 9, 28049 Madrid, Spain;
- Correspondence:
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Zhang W, Qiu Y, Zhou L, Yin J, Wang L, Zhi H, Xu K. Development of a Viral RdRp-Assisted Gene Silencing System and Its Application in the Identification of Host Factors of Plant (+)RNA Virus. Front Microbiol 2021; 12:682921. [PMID: 34394029 PMCID: PMC8358433 DOI: 10.3389/fmicb.2021.682921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/24/2021] [Indexed: 11/13/2022] Open
Abstract
Gene silencing induced by hairpin RNA or virus infection expression is one of the major tools in genetics studies in plants. However, when dealing with essential genes, virus-induced gene silencing (VIGS) and transgenic expression of hairpin RNA could lead to plant death, while transient expression of hairpin RNA in leaves is often less competent in downregulating target gene mRNA levels. Here, we developed a transient double-stranded RNA (dsRNA) expression system assisted by a modified viral RNA-dependent RNA polymerase (RdRp) in plant leaves. We show that this system is more effective in inducing gene silencing than the intron-spliced hairpin RNA expression. Furthermore, by using this system, we tested the role of the early secretory pathway during infection of Soybean mosaic potyvirus (SMV). We found that key components of the coat protein complex II vesicles are required for the multiplication of SMV. Overall, this dsRNA-based gene silencing system is effective in downregulating plant gene expression and can be used to identify host genes involved in plant-virus interactions.
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Affiliation(s)
- Wang Zhang
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Yanglin Qiu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Lingyun Zhou
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
| | - Jinlong Yin
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean-Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Liqun Wang
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean-Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Haijian Zhi
- National Center for Soybean Improvement, National Key Laboratory for Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Genetic Improvement of Soybean-Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Kai Xu
- Jiangsu Key Laboratory for Microbes and Functional Genomics, College of Life Sciences, Nanjing Normal University, Nanjing, China
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Adalat B, Rahim F, Taha M, Alshamrani FJ, Anouar EH, Uddin N, Shah SAA, Ali Z, Zakaria ZA. Synthesis of Benzimidazole-Based Analogs as Anti Alzheimer's Disease Compounds and Their Molecular Docking Studies. Molecules 2020; 25:E4828. [PMID: 33092223 DOI: 10.3390/molecules25204828] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 10/14/2020] [Accepted: 10/16/2020] [Indexed: 12/22/2022] Open
Abstract
We synthesized 10 analogs of benzimidazole-based thiosemicarbazide 1 (a-j) and 13 benzimidazole-based Schiff bases 2 (a-m), and characterized by various spectroscopic techniques and evaluated in vitro for acetylcholinesterase (AchE) and butyrylcholinesterase (BchE) inhibition activities. All the synthesized analogs showed varying degrees of acetylcholinesterase and butyrylcholinesterase inhibitory potentials in comparison to the standard drug (IC50 = 0.016 and 4.5 µM. Amongst these analogs 1 (a-j), compounds 1b, 1c, and 1g having IC50 values 1.30, 0.60, and 2.40 µM, respectively, showed good acetylcholinesterase inhibition when compared with the standard. These compounds also showed moderate butyrylcholinesterase inhibition having IC50 values of 2.40, 1.50, and 2.40 µM, respectively. The rest of the compounds of this series also showed moderate to weak inhibition. While amongst the second series of analogs 2 (a-m), compounds 2c, 2e, and 2h having IC50 values of 1.50, 0.60, and 0.90 µM, respectively, showed moderate acetylcholinesterase inhibition when compared to donepezil. Structure Aactivity Relation of both synthesized series has been carried out. The binding interactions between the synthesized analogs and the enzymes were identified through molecular docking simulations.
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Lin HY, Ko CY, Kao TJ, Yang WB, Tsai YT, Chuang JY, Hu SL, Yang PY, Lo WL, Hsu TI. CYP17A1 Maintains the Survival of Glioblastomas by Regulating SAR1-Mediated Endoplasmic Reticulum Health and Redox Homeostasis. Cancers (Basel) 2019; 11:cancers11091378. [PMID: 31527549 PMCID: PMC6770831 DOI: 10.3390/cancers11091378] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 09/11/2019] [Accepted: 09/12/2019] [Indexed: 12/30/2022] Open
Abstract
Cytochrome P450 (CYP) 17A1 is an important steroidogenic enzyme harboring 17α-hydroxylase and performing 17,20 lyase activities in multiple steps of steroid hormone synthesis, including dehydroepiandrosterone (DHEA) biosynthesis. Previously, we showed that CYP17A1-mediated DHEA production clearly protects glioblastomas from temozolomide-induced apoptosis, leading to drug resistance. Herein, we attempt to clarify whether the inhibition of CYP17A1 has a tumor-suppressive effect, and to determine the steroidogenesis-independent functions of CYP17A1 in glioblastomas. Abiraterone, an inhibitor of CYP17A1, significantly inhibits the proliferation of A172, T98G, and PT#3 (the primary glioblastoma cells) by inducing apoptosis. In parallel, abiraterone potently suppresses tumor growth in mouse models through transplantation of PT#3 cells to the back or to the brain. Based on evidence that abiraterone induces endoplasmic reticulum (ER) stress, followed by the accumulation of reactive oxygen species (ROS), CYP17A1 is important for ER health and redox homeostasis. To confirm our hypothesis, we showed that CYP17A1 overexpression prevents the initiation of ER stress and attenuates ROS production by regulating SAR1a/b expression. Abiraterone dissociates SAR1a/b from ER-localized CYP17A1, and induces SAR1a/b ubiquitination, leading to degradation. Furthermore, SAR1 overexpression rescues abiraterone-induced apoptosis and impairs redox homeostasis. In addition to steroid hormone synthesis, CYP17A1 associates with SAR1a/b to regulate protein processing and maintain ER health in glioblastomas.
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Affiliation(s)
- Hong-Yi Lin
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, 11031 Taipei, Taiwan.
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 11031, Taiwan.
| | - Chiung-Yuan Ko
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, 11031 Taipei, Taiwan.
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 11031, Taiwan.
- TMU Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan.
- TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei 11031, Taiwan.
| | - Tzu-Jen Kao
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, 11031 Taipei, Taiwan.
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 11031, Taiwan.
- TMU Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan.
| | - Wen-Bin Yang
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
| | - Yu-Ting Tsai
- Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
| | - Jian-Ying Chuang
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, 11031 Taipei, Taiwan.
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 11031, Taiwan.
- TMU Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan.
- TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei 11031, Taiwan.
| | - Siou-Lian Hu
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, 11031 Taipei, Taiwan.
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 11031, Taiwan.
- TMU Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan.
| | - Pei-Yu Yang
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, 11031 Taipei, Taiwan.
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 11031, Taiwan.
- TMU Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan.
| | - Wei-Lun Lo
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, 11031 Taipei, Taiwan.
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 11031, Taiwan.
- Division of Neurosurgery, Taipei Medical University-Shuang-Ho Hospital, New Taipei City 23561, Taiwan.
| | - Tsung-I Hsu
- Graduate Institute of Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University, 11031 Taipei, Taiwan.
- Ph.D. Program for Neural Regenerative Medicine, College of Medical Science and Technology, Taipei Medical University and National Health Research Institutes, Taipei 11031, Taiwan.
- TMU Research Center of Neuroscience, Taipei Medical University, Taipei, Taiwan.
- TMU Research Center of Cancer Translational Medicine, Taipei Medical University, Taipei 11031, Taiwan.
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Bravo-Plaza I, Hernández-González M, Pinar M, Díaz JF, Peñalva MA. Identification of the guanine nucleotide exchange factor for SAR1 in the filamentous fungal model Aspergillus nidulans. Biochim Biophys Acta Mol Cell Res 2019; 1866:118551. [PMID: 31487505 DOI: 10.1016/j.bbamcr.2019.118551] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/02/2019] [Accepted: 08/11/2019] [Indexed: 12/30/2022]
Abstract
In spite of its basic and applied interest, the regulation of ER exit by filamentous fungi is insufficiently understood. In previous work we isolated a panel of conditional mutations in sarA encoding the master GTPase SarASAR1 in A. nidulans and demonstrated its key role in exocytosis and hyphal morphogenesis. However, the SAR1 guanine nucleotide exchange factor (GEF), Sec12, has not been characterized in any filamentous fungus, largely due to the fact that SEC12 homologues share little amino acid sequence identity beyond a GGGGxxxxGϕxN motif involved in guanine nucleotide exchange. Here we demonstrate that AN11127 encodes A. nidulans Sec12, which is an essential protein that localizes to the ER and that, when overexpressed, rescues the growth defect resulting from a hypomorphic sarA6ts mutation at 37 °C. Using purified, bacterially expressed proteins we demonstrate that the product of AN11127 accelerates nucleotide exchange on SarASAR1, but not on its closely related GTPase ArfAARF1, as expected for a bona fide GEF. The unequivocal characterization of A. nidulans Sec12 paves the way for the tailored modification of ER exit in a model organism that is closely related to industrial species of filamentous fungi.
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Kovalchuk V, Samluk Ł, Juraszek B, Jurkiewicz-Trząska D, Sucic S, Freissmuth M, Nałęcz KA. Trafficking of the amino acid transporter B 0,+ (SLC6A14) to the plasma membrane involves an exclusive interaction with SEC24C for its exit from the endoplasmic reticulum. Biochim Biophys Acta Mol Cell Res 2018; 1866:252-263. [PMID: 30445147 PMCID: PMC6314439 DOI: 10.1016/j.bbamcr.2018.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 11/02/2018] [Accepted: 11/12/2018] [Indexed: 12/16/2022]
Abstract
A plasma membrane amino acid transporter B0,+ (ATB0,+), encoded by the SLC6A14 gene, is specific for neutral and basic amino acids. It is up-regulated in several types of malignant cancers. Neurotransmitter transporters of the SLC6 family interact with specific SEC24 proteins of the COPII complex along their pathway from the endoplasmic reticulum (ER) to Golgi. This study focused on the possible role of SEC24 proteins in ATB0,+ trafficking. Rat ATB0,+ was expressed in HEK293 cells, its localization and trafficking were examined by Western blot, deglycosylation, immunofluorescence (co-localization with ER and trans-Golgi markers) and biotinylation. The expression of ATB0,+ at the plasma membrane was decreased by dominant negative mutants of SAR1, a GTPase, whose activity triggers the formation of the COPII complex. ATB0,+ co-precipitated with SEC24C (but not with the remaining isoforms A, B and D). This interaction was confirmed by immunocytochemistry and the proximity ligation assay. Co-localization of SEC24C with endogenous ATB0,+ was also observed in MCF-7 breast cancer cells. Contrary to the endogenous transporter, part of the overexpressed ATB0,+ is directed to proteolysis, a process significantly reversed by a proteasome inhibitor bortezomib. Co-transfection with a SEC24C dominant negative mutant attenuated ATB0,+ expression at the plasma membrane, due to proteolytic degradation. These results support a hypothesis that lysine at position +2 downstream of the ER export "RI" motif on the cargo protein is crucial for SEC24C binding and for further trafficking to the Golgi. Moreover, there is an equilibrium between ER export and degradation mechanisms in case of overexpressed transporter.
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Affiliation(s)
- Vasylyna Kovalchuk
- Laboratory of Transport through Biomembranes, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Łukasz Samluk
- Laboratory of Transport through Biomembranes, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Barbara Juraszek
- Laboratory of Transport through Biomembranes, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Dominika Jurkiewicz-Trząska
- Laboratory of Transport through Biomembranes, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Sonja Sucic
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Michael Freissmuth
- Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Katarzyna A Nałęcz
- Laboratory of Transport through Biomembranes, Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
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Ito Y, Uemura T, Nakano A. The Golgi entry core compartment functions as a COPII-independent scaffold for ER-to-Golgi transport in plant cells. J Cell Sci 2018; 131:jcs.203893. [PMID: 28839076 DOI: 10.1242/jcs.203893] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 08/17/2017] [Indexed: 12/12/2022] Open
Abstract
Many questions remain about how the stacked structure of the Golgi is formed and maintained. In our previous study, we challenged this question using tobacco BY-2 cells and revealed that, upon Brefeldin A (BFA) treatment, previously undescribed small punctate structures containing a particular subset of cis-Golgi proteins are formed adjacent to the ER-exit sites and act as scaffolds for Golgi regeneration after BFA removal. In this study, we analyzed these structures further. The proteins that localize to these punctate structures originate from the cis-most cisternae. 3D time-lapse observations show that the trans-Golgi marker is transported through these structures during Golgi regeneration. These data indicate that the cis-most cisternae have a specialized region that receives cargo from the ER, which becomes obvious upon BFA treatment. Expression of a dominant mutant form of SAR1 does not affect the formation of the punctate structures. We propose to call these punctate structures the 'Golgi entry core compartment' (GECCO). They act as receivers for the rest of the Golgi materials and are formed independently of the COPII machinery.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Yoko Ito
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan
| | - Tomohiro Uemura
- Laboratory of Developmental Cell Biology, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Akihiko Nakano
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, Wako, Saitama 351-0198, Japan.,Laboratory of Developmental Cell Biology, Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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Saito K, Maeda M, Katada T. Regulation of the Sar1 GTPase Cycle Is Necessary for Large Cargo Secretion from the Endoplasmic Reticulum. Front Cell Dev Biol 2017; 5:75. [PMID: 28879181 PMCID: PMC5572378 DOI: 10.3389/fcell.2017.00075] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 08/10/2017] [Indexed: 12/22/2022] Open
Abstract
Proteins synthesized within the endoplasmic reticulum (ER) are transported to the Golgi via coat protein complex II (COPII)-coated vesicles. The formation of COPII-coated vesicles is regulated by the GTPase cycle of Sar1. Activated Sar1 is recruited to ER membranes and forms a pre-budding complex with cargoes and the inner-coat complex. The outer-coat complex then stimulates Sar1 inactivation and completes vesicle formation. The mechanisms of forming transport carriers are well-conserved among species; however, in mammalian cells, several cargo molecules such as collagen, and chylomicrons are too large to be accommodated in conventional COPII-coated vesicles. Thus, special cargo-receptor complexes are required for their export from the ER. cTAGE5/TANGO1 complexes and their isoforms have been identified as cargo receptors for these macromolecules. Recent reports suggest that the cTAGE5/TANGO1 complex interacts with the GEF and the GAP of Sar1 and tightly regulates its GTPase cycle to accomplish large cargo secretion.
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Affiliation(s)
- Kota Saito
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of TokyoTokyo, Japan
| | - Miharu Maeda
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of TokyoTokyo, Japan
| | - Toshiaki Katada
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, University of TokyoTokyo, Japan
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Sun J, Yu S, Zhang X, Capac C, Aligbe O, Daudelin T, Bonder EM, Gao N. A Wntless-SEC12 complex on the ER membrane regulates early Wnt secretory vesicle assembly and mature ligand export. J Cell Sci 2017; 130:2159-2171. [PMID: 28515233 DOI: 10.1242/jcs.200634] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 05/11/2017] [Indexed: 01/02/2023] Open
Abstract
Wntless (Wls) transports Wnt molecules for secretion; however, the cellular mechanism underlying the initial assembly of Wnt secretory vesicles is still not fully defined. Here, we performed proteomic and mutagenic analyses of mammalian Wls, and report a mechanism for formation of early Wnt secretory vesicles on ER membrane. Wls forms a complex with SEC12 (also known as PREB), an ER membrane-localized guanine nucleotide-exchange factor (GEF) activator of the SAR1 (the SAR1A isoform) small GTPase. Compared to palmitoylation-deficient Wnt molecules, binding of mature Wnt to Wls increases Wls-SEC12 interaction and promotes association of Wls with SAR1, the key activator of the COPII machinery. Incorporation of Wls into this exporting ER compartment is affected by Wnt ligand binding and SEC12 binding to Wls, as well as the structural integrity and, potentially, the folding of the cytosolic tail of Wls. In contrast, Wls-SEC12 binding is stable, with the interacting interface biochemically mapped to cytosolic segments of individual proteins. Mutant Wls that fails to communicate with the COPII machinery cannot effectively support Wnt secretion. These data suggest that formation of early Wnt secretory vesicles is carefully regulated to ensure proper export of functional ligands.
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Affiliation(s)
- Jiaxin Sun
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | - Shiyan Yu
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | - Xiao Zhang
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | - Catherine Capac
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | | | - Timothy Daudelin
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | - Edward M Bonder
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA
| | - Nan Gao
- Department of Biological Sciences, Rutgers University, Newark, NJ, USA .,Rutgers Cancer Institute of New Jersey, Rutgers University, Piscataway, NJ, USA
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Karim S, Aronsson H. The puzzle of chloroplast vesicle transport - involvement of GTPases. Front Plant Sci 2014; 5:472. [PMID: 25295043 PMCID: PMC4171996 DOI: 10.3389/fpls.2014.00472] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Accepted: 08/28/2014] [Indexed: 05/04/2023]
Abstract
In the cytosol of plant cells vesicle transport occurs via secretory pathways among the endoplasmic reticulum network, Golgi bodies, secretory granules, endosome, and plasma membrane. Three systems transfer lipids, proteins and other important molecules through aqueous spaces to membrane-enclosed compartments, via vesicles that bud from donor membranes, being coated and uncoated before tethered and fused with acceptor membranes. In addition, molecular, biochemical and ultrastructural evidence indicates presence of a vesicle transport system in chloroplasts. Little is known about the protein components of this system. However, as chloroplasts harbor the photosynthetic apparatus that ultimately supports most organisms on the planet, close attention to their pathways is warranted. This may also reveal novel diversification and/or distinct solutions to the problems posed by the targeted intra-cellular trafficking of important molecules. To date two homologs to well-known yeast cytosolic vesicle transport proteins, CPSAR1 and CPRabA5e (CP, chloroplast localized), have been shown to have roles in chloroplast vesicle transport, both being GTPases. Bioinformatic data indicate that several homologs of cytosolic vesicle transport system components are putatively chloroplast-localized and in addition other proteins have been implicated to participate in chloroplast vesicle transport, including vesicle-inducing protein in plastids 1, thylakoid formation 1, snowy cotyledon 2/cotyledon chloroplast biogenesis factor, curvature thylakoid 1 proteins, and a dynamin like GTPase FZO-like protein. Several putative potential cargo proteins have also been identified, including building blocks of the photosynthetic apparatus. Here we discuss details of the largely unknown putative chloroplast vesicle transport system, focusing on GTPase-related components.
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Affiliation(s)
| | - Henrik Aronsson
- *Correspondence: Henrik Aronsson, Department of Biological and Environmental Sciences, University of Gothenburg, Box 461, 405 30 Gothenburg, Sweden e-mail:
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Hopff D, Wienkoop S, Lüthje S. The plasma membrane proteome of maize roots grown under low and high iron conditions. J Proteomics 2013; 91:605-18. [PMID: 23353019 DOI: 10.1016/j.jprot.2013.01.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 12/11/2012] [Accepted: 01/09/2013] [Indexed: 10/27/2022]
Abstract
Iron (Fe) homeostasis is essential for life and has been intensively investigated for dicots, while our knowledge for species in the Poaceae is fragmentary. This study presents the first proteome analysis (LC-MS/MS) of plasma membranes isolated from roots of 18-day old maize (Zea mays L.). Plants were grown under low and high Fe conditions in hydroponic culture. In total, 227 proteins were identified in control plants, whereas 204 proteins were identified in Fe deficient plants and 251 proteins in plants grown under high Fe conditions. Proteins were sorted by functional classes, and most of the identified proteins were classified as signaling proteins. A significant number of PM-bound redox proteins could be identified including quinone reductases, heme and copper-containing proteins. Most of these components were constitutive, and others could hint at an involvement of redox signaling and redox homeostasis by change in abundance. Energy metabolism and translation seem to be crucial in Fe homeostasis. The response to Fe deficiency includes proteins involved in development, whereas membrane remodeling and assembly and/or repair of Fe-S clusters is discussed for Fe toxicity. The general stress response appears to involve proteins related to oxidative stress, growth regulation, an increased rigidity and synthesis of cell walls and adaption of nutrient uptake and/or translocation. This article is part of a Special Issue entitled: Plant Proteomics in Europe.
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Affiliation(s)
- David Hopff
- University of Hamburg, Biocenter Klein Flottbek and Botanical Garden, Plant Physiology, Ohnhorststraße 18, D-22609 Hamburg, Germany
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