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Menero-Valdés P, Álvarez L, González-Iglesias H, Fernández B, Pereiro R. Unveiling compositional images of specific proteins in individual cells by LA-ICP-MS: Labelling with ruthenium red and metal nanoclusters. Anal Chim Acta 2024; 1317:342906. [PMID: 39030007 DOI: 10.1016/j.aca.2024.342906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/29/2024] [Accepted: 06/23/2024] [Indexed: 07/21/2024]
Abstract
BACKGROUND Recent biological studies have demonstrated that changes can occur in the cellular genome and proteome due to variations in cell volume. Therefore, it is imperative to take cell volume into account when analyzing a target protein. This consideration becomes especially critical in experimental models involving cells subjected to different treatments. Failure to consider cell volume could obscure the studied biological phenomena or lead to erroneous conclusions. However, quantitative imaging of proteins within cells by LA-ICP-MS is limited by the lack of methods that provide the protein concentration (protein mass over cell volume) rather than just protein mass within individual cells. RESULTS The combination of a metal tagged immunoprobe with ruthenium red (RR) labelling enables the simultaneous analysis of a specific protein and the cell volume in each cell analyzed by LA-ICP-(Q)MS. The results indicate that the CYP1B1 concentration exhibits a quasi-normally distribution in control ARPE-19 cells, whereas AAPH-treated cells reveal the presence of two distinct cell groups, responding and non-responding cells to an in vitro induced oxidative stress. The labelling of the membrane with RR and the measurement of Ru mass in each cell by LA-ICP-MS offers higher precision compared to manually delimitation of the cell perimeter and eliminates the risk of biased information, which can be prone to inter-observer variability. The proposed procedure is fast and minimizes errors in cell area assignment and offers the possibility to carry out a faster data treatment approach if just relative volumes are compared, which can be advantageous for specific applications. SIGNIFICANCE AND NOVELTY This work presents an innovative strategy to directly study the distribution and concentration of proteins within individual cells by LA-ICP-MS. This method employs ruthenium red as a cell volume marker and Au nanoclusters (AuNCs) tagged immunoprobes to label the protein of interest. Furthermore, the proposed labelling strategy enables rapid data processing, allowing for the calculation of relative concentrations and thus facilitating the comparison across large datasets. As a proof-of-concept, the concentration of the CYP1B1 protein was quantified in ARPE-19 cells under both control and oxidative stress conditions.
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Affiliation(s)
- Paula Menero-Valdés
- Department of Physical and Analytical Chemistry, University of Oviedo, Faculty of Chemistry, Avda. Julián Clavería 8, 33006, Oviedo, Spain
| | - Lydia Álvarez
- Fundación de Investigación Oftalmológica (FIO), Avda. Dres. Fernández-Vega, 34, 33012, Oviedo, Spain
| | - Héctor González-Iglesias
- Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Villaviciosa, Spain
| | - Beatriz Fernández
- Department of Physical and Analytical Chemistry, University of Oviedo, Faculty of Chemistry, Avda. Julián Clavería 8, 33006, Oviedo, Spain.
| | - Rosario Pereiro
- Department of Physical and Analytical Chemistry, University of Oviedo, Faculty of Chemistry, Avda. Julián Clavería 8, 33006, Oviedo, Spain
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Comparison of the Cisterna Maturation-Progression Model with the Kiss-and-Run Model of Intra-Golgi Transport: Role of Cisternal Pores and Cargo Domains. Int J Mol Sci 2022; 23:ijms23073590. [PMID: 35408951 PMCID: PMC8999060 DOI: 10.3390/ijms23073590] [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] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 03/11/2022] [Accepted: 03/16/2022] [Indexed: 12/22/2022] Open
Abstract
The Golgi complex is the central station of the secretory pathway. Knowledge about the mechanisms of intra-Golgi transport is inconsistent. Here, we compared the explanatory power of the cisterna maturation-progression model and the kiss-and-run model. During intra-Golgi transport, conventional cargoes undergo concentration and form cisternal distensions or distinct membrane domains that contain only one membrane cargo. These domains and distension are separated from the rest of the Golgi cisternae by rows of pores. After the arrival of any membrane cargo or a large cargo aggregate at the Golgi complex, the cis-Golgi SNAREs become enriched within the membrane of cargo-containing domains and then replaced by the trans-Golgi SNAREs. During the passage of these domains, the number of cisternal pores decreases. Restoration of the cisternal pores is COPI-dependent. Our observations are more in line with the kiss-and-run model.
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Assembly and Cellular Exit of Coronaviruses: Hijacking an Unconventional Secretory Pathway from the Pre-Golgi Intermediate Compartment via the Golgi Ribbon to the Extracellular Space. Cells 2021; 10:cells10030503. [PMID: 33652973 PMCID: PMC7996754 DOI: 10.3390/cells10030503] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 12/20/2022] Open
Abstract
Coronaviruses (CoVs) assemble by budding into the lumen of the intermediate compartment (IC) at the endoplasmic reticulum (ER)-Golgi interface. However, why CoVs have chosen the IC as their intracellular site of assembly and how progeny viruses are delivered from this compartment to the extracellular space has remained unclear. Here we address these enigmatic late events of the CoV life cycle in light of recently described properties of the IC. Of particular interest are the emerging spatial and functional connections between IC elements and recycling endosomes (REs), defined by the GTPases Rab1 and Rab11, respectively. The establishment of IC-RE links at the cell periphery, around the centrosome and evidently also at the noncompact zones of the Golgi ribbon indicates that—besides traditional ER-Golgi communication—the IC also promotes a secretory process that bypasses the Golgi stacks, but involves its direct connection with the endocytic recycling system. The initial confinement of CoVs to the lumen of IC-derived large transport carriers and their preferential absence from Golgi stacks is consistent with the idea that they exit cells following such an unconventional route. In fact, CoVs may share this pathway with other intracellularly budding viruses, lipoproteins, procollagen, and/or protein aggregates experimentally introduced into the IC lumen.
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Structure of the enterocyte transcytosis compartments during lipid absorption. Histochem Cell Biol 2020; 153:413-429. [DOI: 10.1007/s00418-020-01851-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2020] [Indexed: 12/14/2022]
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Mironov AA, Beznoussenko GV. Models of Intracellular Transport: Pros and Cons. Front Cell Dev Biol 2019; 7:146. [PMID: 31440506 PMCID: PMC6693330 DOI: 10.3389/fcell.2019.00146] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 07/16/2019] [Indexed: 12/22/2022] Open
Abstract
Intracellular transport is one of the most confusing issues in the field of cell biology. Many different models and their combinations have been proposed to explain the experimental data on intracellular transport. Here, we analyse the data related to the mechanisms of endoplasmic reticulum-to-Golgi and intra-Golgi transport from the point of view of the main models of intracellular transport; namely: the vesicular model, the diffusion model, the compartment maturation–progression model, and the kiss-and-run model. This review initially describes our current understanding of Golgi function, while highlighting the recent progress that has been made. It then continues to discuss the outstanding questions and potential avenues for future research with regard to the models of these transport steps. To compare the power of these models, we have applied the method proposed by K. Popper; namely, the formulation of prohibitive observations according to, and the consecutive evaluation of, previous data, on the basis on the new models. The levels to which the different models can explain the experimental observations are different, and to date, the most powerful has been the kiss-and-run model, whereas the least powerful has been the diffusion model.
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Affiliation(s)
- Alexander A Mironov
- Department of Cell Biology, The FIRC Institute of Molecular Oncology, Milan, Italy
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6
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Mironov AA, Dimov ID, Beznoussenko GV. Role of Intracellular Transport in the Centriole-Dependent Formation of Golgi Ribbon. Results Probl Cell Differ 2019; 67:49-79. [PMID: 31435792 DOI: 10.1007/978-3-030-23173-6_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The intracellular transport is the most confusing issue in the field of cell biology. The Golgi complex (GC) is the central station along the secretory pathway. It contains Golgi glycosylation enzymes, which are responsible for protein and lipid glycosylation, and in many cells, it is organized into a ribbon. Position and structure of the GC depend on the position and function of the centriole. Here, we analyze published data related to the role of centriole and intracellular transport (ICT) for the formation of Golgi ribbon and specifically stress the importance of the delivery of membranes containing cargo and membrane proteins to the cell centre where centriole/centrosome is localized. Additionally, we re-examined the formation of Golgi ribbon from the point of view of different models of ICT.
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Affiliation(s)
| | - Ivan D Dimov
- Department of Anatomy, Saint Petersburg State Paediatric Medical University, Saint Petersburg, Russia
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7
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Lipid transfer proteins and the tuning of compartmental identity in the Golgi apparatus. Chem Phys Lipids 2016; 200:42-61. [DOI: 10.1016/j.chemphyslip.2016.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 06/21/2016] [Accepted: 06/22/2016] [Indexed: 11/23/2022]
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Bergeron JJM, Di Guglielmo GM, Dahan S, Dominguez M, Posner BI. Spatial and Temporal Regulation of Receptor Tyrosine Kinase Activation and Intracellular Signal Transduction. Annu Rev Biochem 2016; 85:573-97. [PMID: 27023845 DOI: 10.1146/annurev-biochem-060815-014659] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epidermal growth factor (EGF) and insulin receptor tyrosine kinases (RTKs) exemplify how receptor location is coupled to signal transduction. Extracellular binding of ligands to these RTKs triggers their concentration into vesicles that bud off from the cell surface to generate intracellular signaling endosomes. On the exposed cytosolic surface of these endosomes, RTK autophosphorylation selects the downstream signaling proteins and lipids to effect growth factor and polypeptide hormone action. This selection is followed by the recruitment of protein tyrosine phosphatases that inactivate the RTKs and deliver them by membrane fusion and fission to late endosomes. Coincidentally, proteinases inside the endosome cleave the EGF and insulin ligands. Subsequent inward budding of the endosomal membrane generates multivesicular endosomes. Fusion with lysosomes then results in RTK degradation and downregulation. Through the spatial positioning of RTKs in target cells for EGF and insulin action, the temporal extent of signaling, attenuation, and downregulation is regulated.
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Affiliation(s)
- John J M Bergeron
- Department of Medicine, McGill University Hospital Research Institute, Montreal, Quebec, Canada H4A 3J1; , , ,
| | - Gianni M Di Guglielmo
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada N6A 5C1;
| | - Sophie Dahan
- Department of Medicine, McGill University Hospital Research Institute, Montreal, Quebec, Canada H4A 3J1; , , ,
| | - Michel Dominguez
- Department of Medicine, McGill University Hospital Research Institute, Montreal, Quebec, Canada H4A 3J1; , , ,
| | - Barry I Posner
- Department of Medicine, McGill University Hospital Research Institute, Montreal, Quebec, Canada H4A 3J1; , , ,
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Au CE, Hermo L, Byrne E, Smirle J, Fazel A, Simon PHG, Kearney RE, Cameron PH, Smith CE, Vali H, Fernandez-Rodriguez J, Ma K, Nilsson T, Bergeron JJM. Expression, sorting, and segregation of Golgi proteins during germ cell differentiation in the testis. Mol Biol Cell 2015; 26:4015-32. [PMID: 25808494 PMCID: PMC4710233 DOI: 10.1091/mbc.e14-12-1632] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/19/2015] [Indexed: 12/14/2022] Open
Abstract
A total of 1318 proteins characterized in the male germ cell Golgi apparatus reveal a new germ cell–specific Golgi marker and a new pan-Golgi marker for all cells. The localization of these and other Golgi proteins reveals differential expression linked to mitosis, meiosis, acrosome formation, and postacrosome Golgi migration and destination in the late spermatid. The molecular basis of changes in structure, cellular location, and function of the Golgi apparatus during male germ cell differentiation is unknown. To deduce cognate Golgi proteins, we isolated germ cell Golgi fractions, and 1318 proteins were characterized, with 20 localized in situ. The most abundant protein, GL54D of unknown function, is characterized as a germ cell–specific Golgi-localized type II integral membrane glycoprotein. TM9SF3, also of unknown function, was revealed to be a universal Golgi marker for both somatic and germ cells. During acrosome formation, several Golgi proteins (GBF1, GPP34, GRASP55) localize to both the acrosome and Golgi, while GL54D, TM9SF3, and the Golgi trafficking protein TMED7/p27 are segregated from the acrosome. After acrosome formation, GL54D, TM9SF3, TMED4/p25, and TMED7/p27 continue to mark Golgi identity as it migrates away from the acrosome, while the others (GBF1, GPP34, GRASP55) remain in the acrosome and are progressively lost in later steps of differentiation. Cytoplasmic HSP70.2 and the endoplasmic reticulum luminal protein-folding enzyme PDILT are also Golgi recruited but only during acrosome formation. This resource identifies abundant Golgi proteins that are expressed differentially during mitosis, meiosis, and postacrosome Golgi migration, including the last step of differentiation.
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Affiliation(s)
- Catherine E Au
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Louis Hermo
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Elliot Byrne
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Jeffrey Smirle
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Ali Fazel
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Paul H G Simon
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Robert E Kearney
- Department of Biomedical Engineering Department, McGill University, Montreal, QC H3A 2B4, Canada
| | - Pamela H Cameron
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Charles E Smith
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Hojatollah Vali
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada
| | - Julia Fernandez-Rodriguez
- Centre for Cellular Imaging, Sahlgrenska Academy, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Kewei Ma
- Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - Tommy Nilsson
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
| | - John J M Bergeron
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 0C7, Canada Division of Endocrinology and Metabolism, McGill University Health Centre Research Institute, Montreal, QC H3A 1A1, Canada
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Beznoussenko GV, Parashuraman S, Rizzo R, Polishchuk R, Martella O, Di Giandomenico D, Fusella A, Spaar A, Sallese M, Capestrano MG, Pavelka M, Vos MR, Rikers YGM, Helms V, Mironov AA, Luini A. Transport of soluble proteins through the Golgi occurs by diffusion via continuities across cisternae. eLife 2014; 3:e02009. [PMID: 24867214 PMCID: PMC4070021 DOI: 10.7554/elife.02009] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 05/25/2014] [Indexed: 12/18/2022] Open
Abstract
The mechanism of transport through the Golgi complex is not completely understood, insofar as no single transport mechanism appears to account for all of the observations. Here, we compare the transport of soluble secretory proteins (albumin and α1-antitrypsin) with that of supramolecular cargoes (e.g., procollagen) that are proposed to traverse the Golgi by compartment progression-maturation. We show that these soluble proteins traverse the Golgi much faster than procollagen while moving through the same stack. Moreover, we present kinetic and morphological observations that indicate that albumin transport occurs by diffusion via intercisternal continuities. These data provide evidence for a transport mechanism that applies to a major class of secretory proteins and indicate the co-existence of multiple intra-Golgi trafficking modes.
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Affiliation(s)
- Galina V Beznoussenko
- Fondazione IFOM, Istituto FIRC di Oncologia Molecolare (IFOM-IEO Campus), Milan, Italy
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
| | - Seetharaman Parashuraman
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
- Institute of Protein Biochemistry, Consiglio Nazionale Delle Ricerche (CNR-IBP), Naples, Italy
| | - Riccardo Rizzo
- Institute of Protein Biochemistry, Consiglio Nazionale Delle Ricerche (CNR-IBP), Naples, Italy
| | - Roman Polishchuk
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
- Telethon Institute for Genetics and Medicine (TIGEM), Naples, Italy
| | - Oliviano Martella
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
| | - Daniele Di Giandomenico
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
| | - Aurora Fusella
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
| | - Alexander Spaar
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
| | - Michele Sallese
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
| | - Maria Grazia Capestrano
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
| | - Margit Pavelka
- Department of Cell Biology and Ultrastructure Research, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | | | | | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbruecken, Germany
| | - Alexandre A Mironov
- Fondazione IFOM, Istituto FIRC di Oncologia Molecolare (IFOM-IEO Campus), Milan, Italy
| | - Alberto Luini
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Italy
- Institute of Protein Biochemistry, Consiglio Nazionale Delle Ricerche (CNR-IBP), Naples, Italy
- Telethon Institute for Genetics and Medicine (TIGEM), Naples, Italy
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Mironov AA, Sesorova IV, Beznoussenko GV. Golgi's way: a long path toward the new paradigm of the intra-Golgi transport. Histochem Cell Biol 2013; 140:383-93. [PMID: 24068461 DOI: 10.1007/s00418-013-1141-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2013] [Indexed: 11/28/2022]
Abstract
The transport of proteins and lipids is one of the main cellular functions. The vesicular model, compartment (or cisterna) maturation model, and the diffusion model compete with each other for the right to be the paradigm within the field of the intra-Golgi transport. These models have significant difficulties explaining the existing experimental data. Recently, we proposed the kiss-and-run (KAR) model of intra-Golgi transport (Mironov and Beznoussenko in Int J Mol Sci 13(6):6800-6819, 2012), which can be symmetric, when fusion and fission occur in the same location, and asymmetric, when fusion and fission take place at different sites. Here, we compare the ability of main models of the intra-Golgi transport to explain the existing results examining the evidence in favor and against each model. We propose that the KAR model has the highest potential for the explanation of the majority of experimental observations existing within the field of intracellular transport.
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Affiliation(s)
- Alexander A Mironov
- Istituto di Oncologia Molecolare di Fondazione Italiana per la Ricerca sul Cancro, 20139, Milan, Italy,
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Smirle J, Au CE, Jain M, Dejgaard K, Nilsson T, Bergeron J. Cell biology of the endoplasmic reticulum and the Golgi apparatus through proteomics. Cold Spring Harb Perspect Biol 2013; 5:a015073. [PMID: 23284051 DOI: 10.1101/cshperspect.a015073] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Enriched endoplasmic reticulum (ER) and Golgi membranes subjected to mass spectrometry have uncovered over a thousand different proteins assigned to the ER and Golgi apparatus of rat liver. This, in turn, led to the uncovering of several hundred proteins of poorly understood function and, through hierarchical clustering, showed that proteins distributed in patterns suggestive of microdomains in cognate organelles. This has led to new insights with respect to their intracellular localization and function. Another outcome has been the critical testing of the cisternal maturation hypothesis showing overwhelming support for a predominant role of COPI vesicles in the transport of resident proteins of the ER and Golgi apparatus (as opposed to biosynthetic cargo). Here we will discuss new insights gained and also highlight new avenues undertaken to further explore the cell biology of the ER and the Golgi apparatus through tandem mass spectrometry.
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Affiliation(s)
- Jeffrey Smirle
- The Research Institute of the McGill University Health Centre and the Department of Medicine, McGill University, Montreal, Quebec H3A 1A1, Canada
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Gannon J, Bergeron JJM, Nilsson T. Golgi and related vesicle proteomics: simplify to identify. Cold Spring Harb Perspect Biol 2011; 3:cshperspect.a005421. [PMID: 21813401 DOI: 10.1101/cshperspect.a005421] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Despite more than six decades of successful Golgi research, the fundamental question as to how biosynthetic material is transported through the secretory pathway remains unanswered. New technologies such as live cell imaging and correlative microscopy have highlighted the plastic nature of the Golgi, one that is sensitive to perturbation yet highly efficient in regaining both structure and function. Single molecule-microscopy and super resolution-microscopy further adds to this picture. Various models for protein transport have been put forward, each with its own merits and pitfalls but we are far from resolving whether one is more correct than the other. As such, our laboratory considers multiple mechanisms of Golgi transport until proven otherwise. This includes the two classical modes of transport, vesicular transport and cisternal progression/maturation as well as more recent models such as tubular inter- and intra-cisternal connections (long lasting or transient) and inter-Golgi stack transport. In this article, we focus on an emerging inductive technology, mass spectrometry-based proteomics that has already enabled insight into the relative composition of compartments and subcompartments of the secretory pathway including mechanistic aspects of protein transport. We note that proteomics, as with any other technology, is not a stand-alone technology but one that works best alongside complementary approaches.
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Affiliation(s)
- Joan Gannon
- The Research Institute of the McGill University Health Centre and the Department of Medicine, Montreal, Quebec, Canada
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Abstract
A variety of secretory cargoes move through the Golgi, but the pathways and mechanisms of this traffic are still being debated. Here, we evaluate the strengths and weaknesses of five current models for Golgi traffic: (1) anterograde vesicular transport between stable compartments, (2) cisternal progression/maturation, (3) cisternal progression/maturation with heterotypic tubular transport, (4) rapid partitioning in a mixed Golgi, and (5) stable compartments as cisternal progenitors. Each model is assessed for its ability to explain a set of key observations encompassing multiple cell types. No single model can easily explain all of the observations from diverse organisms. However, we propose that cisternal progression/maturation is the best candidate for a conserved core mechanism of Golgi traffic, and that some cells elaborate this core mechanism by means of heterotypic tubular transport between cisternae.
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Affiliation(s)
- Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA.
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Abstract
Newly synthesized secretory cargo molecules pass through the Golgi apparatus while resident Golgi proteins remain in the organelle. However, the pathways of membrane traffic within the Golgi are still uncertain. Most of the available data can be accommodated by the cisternal maturation model, which postulates that Golgi cisternae form de novo, carry secretory cargoes forward and ultimately disappear. The entry face of the Golgi receives material that has been exported from transitional endoplasmic reticulum sites, and the exit face of the Golgi is intimately connected with endocytic compartments. These conserved features are enhanced by cell-type-specific elaborations such as tubular connections between mammalian Golgi cisternae. Key mechanistic questions remain about the formation and maturation of Golgi cisternae, the recycling of resident Golgi proteins, the origins of Golgi compartmental identity, the establishment of Golgi architecture, and the roles of Golgi structural elements in membrane traffic.
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Affiliation(s)
- Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois 60637, USA.
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Kockx M, Jessup W, Kritharides L. Regulation of endogenous apolipoprotein E secretion by macrophages. Arterioscler Thromb Vasc Biol 2008; 28:1060-7. [PMID: 18388328 DOI: 10.1161/atvbaha.108.164350] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Apolipoprotein E has critical roles in the protection against atherosclerosis and is understood to follow the classical constitutive secretion pathway. Recent studies have indicated that the secretion of apoE from macrophages is a regulated process of unexpected complexity. Cholesterol acceptors such as apolipoprotein A-I, high density lipoprotein, and phospholipid vesicles can stimulate apoE secretion. The ATP binding cassette transporter ABCA1 is involved in basal apoE secretion and in lipidating apoE-containing particles secreted by macrophages. However, the stimulation of apoE secretion by apoA-I is ABCA1-independent, indicating the existence of both ABCA1-dependent and -independent pathways of apoE secretion. The release of apoE under basal conditions is also regulated, requiring intact protein kinase A activity, intracellular calcium, and an intact microtubular network. Mathematical modeling of apoE turnover indicates that whereas some pools of apoE are committed to either secretion or degradation, other pools can be diverted from degradation toward secretion. Targeted inhibition or stimulation of specific apoE trafficking pathways will provide unique opportunities to regulate the biology of this important molecule.
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Affiliation(s)
- Maaike Kockx
- Macrophage Biology Group, Centre for Vascular Research, Room 405C Wallace Wurth Building, University of New South Wales, High Street, Kensington, Sydney, NSW 2050, Australia
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Gusarova V, Seo J, Sullivan ML, Watkins SC, Brodsky JL, Fisher EA. Golgi-associated maturation of very low density lipoproteins involves conformational changes in apolipoprotein B, but is not dependent on apolipoprotein E. J Biol Chem 2007; 282:19453-62. [PMID: 17500069 DOI: 10.1074/jbc.m700475200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The major protein component in secreted very low density lipoproteins (VLDL) is apoB, and it is established that these particles can reach sizes approaching 100 nm. We previously employed a cell-free system to investigate the nature of the vesicles in which this large cargo exits the endoplasmic reticulum (ER) (Gusarova, V., Brodsky, J. L., and Fisher, E. A. (2003) J. Biol. Chem. 278, 48051-48058). We found that apoB-containing lipoproteins exit the ER as dense lipid-protein complexes regardless of the final sizes of the particles and that further expansion occurs via post-ER lipidation. Here, we focused on maturation in the Golgi apparatus. In three separate approaches, we found that VLDL maturation (as assessed by changes in buoyant density) was associated with conformational changes in apoB. In addition, as the size of VLDL expanded, apoE concentrated in a subclass of Golgi microsomes or Golgi-derived vesicles that co-migrated with apoB-containing microsomes or vesicles, respectively. A relationship between apoB and apoE was further confirmed in co-localization studies by immunoelectron microscopy. These combined results are consistent with previous suggestions that apoE is required for VLDL maturation. To our surprise, however, we observed robust secretion of mature VLDL when apoE synthesis was inhibited in either rat hepatoma cells or apoE(-/-) mouse primary hepatocytes. We conclude that VLDL maturation in the Golgi involves apoB conformational changes and that the expansion of the lipoprotein does not require apoE; rather, the increase in VLDL surface area favors apoE binding.
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Affiliation(s)
- Viktoria Gusarova
- Department of Medicine, Leon Charney Division of Cardiology, New York University School of Medicine, New York, New York 10016, USA
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19
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Gilchrist A, Au CE, Hiding J, Bell AW, Fernandez-Rodriguez J, Lesimple S, Nagaya H, Roy L, Gosline SJC, Hallett M, Paiement J, Kearney RE, Nilsson T, Bergeron JJM. Quantitative Proteomics Analysis of the Secretory Pathway. Cell 2006; 127:1265-81. [PMID: 17174899 DOI: 10.1016/j.cell.2006.10.036] [Citation(s) in RCA: 356] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 09/20/2006] [Accepted: 10/04/2006] [Indexed: 11/24/2022]
Abstract
We report more than 1400 proteins of the secretory-pathway proteome and provide spatial information on the relative presence of each protein in the rough and smooth ER Golgi cisternae and Golgi-derived COPI vesicles. The data support a role for COPI vesicles in recycling and cisternal maturation, showing that Golgi-resident proteins are present at a higher concentration than secretory cargo. Of the 1400 proteins, 345 were identified as previously uncharacterized. Of these, 230 had their subcellular location deduced by proteomics. This study provides a comprehensive catalog of the ER and Golgi proteomes with insight into their identity and function.
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Affiliation(s)
- Annalyn Gilchrist
- Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec H3A 2B2, Canada
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20
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Rabouille C, Klumperman J. Opinion: The maturing role of COPI vesicles in intra-Golgi transport. Nat Rev Mol Cell Biol 2005; 6:812-7. [PMID: 16167055 DOI: 10.1038/nrm1735] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
COPI vesicles that surround the Golgi stack were first implicated in the anterograde movement of cargo, and then in the retrograde movement of Golgi enzymes. Recently, their role has been challenged again, and we discuss new data that both confirm and modify our view of these carriers.
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Affiliation(s)
- Catherine Rabouille
- The Cell Microscopy Center, Department of Cell Biology and Institute of Biomembranes, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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21
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Lee J, O'Neill RC, Park MW, Gravel M, Braun PE. Mitochondrial localization of CNP2 is regulated by phosphorylation of the N-terminal targeting signal by PKC: implications of a mitochondrial function for CNP2 in glial and non-glial cells. Mol Cell Neurosci 2005; 31:446-62. [PMID: 16343930 DOI: 10.1016/j.mcn.2005.10.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2004] [Revised: 10/25/2005] [Accepted: 10/25/2005] [Indexed: 10/25/2022] Open
Abstract
Both 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNP) isoforms are abundantly expressed in myelinating cells. CNP2 differs from CNP1 by a 20 amino acid N-terminal extension and is also expressed at much lower levels in non-myelinating tissues. The functional role of CNP2, apart from CNP1, and the significance for CNP2 expression in non-myelinating tissues are unknown. Here, we demonstrate that CNP2 is translocated to mitochondria by virtue of a mitochondrial targeting signal at the N-terminus. PKC-mediated phosphorylation of the targeting signal inhibits CNP2 translocation to mitochondria, thus retaining it in the cytoplasm. CNP2 is imported into mitochondria and the targeting signal cleaved, yielding a mature, truncated form similar in size to CNP1. CNP2 is entirely processed in adult liver and embryonic brain, indicating that it is localized specifically to mitochondria in non-myelinating cells. Our results point to a broader biological role for CNP2 in mitochondria that is likely to be different from its specific role in the cytoplasm, along with CNP1, during myelination.
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Affiliation(s)
- John Lee
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada H3G 1Y6.
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22
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Mironov AA, Beznoussenko GV, Polishchuk RS, Trucco A. Intra-Golgi transport: A way to a new paradigm? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1744:340-50. [PMID: 15979506 DOI: 10.1016/j.bbamcr.2005.03.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Revised: 03/11/2005] [Accepted: 03/11/2005] [Indexed: 10/25/2022]
Abstract
The morpho-functional principles of intra-Golgi transport are, surprisingly, still not clear, which is in marked contrast to our advanced knowledge of the underlying molecular machineries. Recently, the conceptual and technological hindrances that had delayed progress in this area have been disappearing, and a cluster of powerful morphological techniques has been revealing new glimpses of the organization of traffic in intact cells. Here, we discuss the new concepts around the present models of intra-Golgi transport.
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Affiliation(s)
- Alexander A Mironov
- Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Via Nazionale, 66030 Santa Maria Imbaro (Chieti), Italy.
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23
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Mori K, Yokoyama A, Yang L, Yang L, Maeda N, Mitsuda N, Tanaka J. L-serine-mediated release of apolipoprotein E and lipids from microglial cells. Exp Neurol 2004; 185:220-31. [PMID: 14736503 DOI: 10.1016/j.expneurol.2003.10.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Apolipoprotein E (ApoE), one of the genetic risk factors for Alzheimer's disease, is considered to have a critical role in transporting lipids in the brain. In the present study, we investigated ApoE release in primary rat microglial cultures. Microglial cells released ApoE in response to L-Ser in culture medium, and ApoE-immunoreactivity was detected in granules in the cell periphery and in perinuclear structures. Immunocytochemical studies, immunoblotting, and reverse transcription-polymerase chain reaction (RT-PCR) results all supported the notion that microglial cells are the potential source of ApoE in the brain. L-Ser enhanced ApoE release in a concentration-dependent manner without upregulating ApoE mRNA expression. Astrocytes presumably enhanced production and release of ApoE by microglial cells through secretion of L-Ser. As revealed by gel chromatography, ApoE was secreted as a component of lipoproteins, and L-Ser enhanced release of cholesterol and triglycerides together with ApoE. Activation of microglial cells by lipopolysaccharides and serum resulted in an overall decrease of the ApoE release. These findings suggest that microglial cells are a significant source of lipoproteins containing ApoE in the brain under physiological conditions, and that L-Ser is an important mediator of the neuron-astrocyte-microglia network in the brain.
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Affiliation(s)
- Kohji Mori
- Department of Physiology, School of Medicine, Ehime University, Ehime 791-0295, Japan
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24
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Képès F, Rambourg A, Satiat-Jeunemaître B. Morphodynamics of the secretory pathway. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 242:55-120. [PMID: 15598467 DOI: 10.1016/s0074-7696(04)42002-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A careful scrutiny of the dynamics of secretory compartments in the entire eukaryotic world reveals many common themes. The most fundamental theme is that the Golgi apparatus and related structures appear as compartments formed by the act of transporting cargo. The second common theme is the pivotal importance for endomembrane dynamics of shifting back and forth the equilibrium between full and perforated cisternae along the pathway. The third theme is the role of a continuous membrane flow in anterograde transfer of molecules from the endoplasmic reticulum through the Golgi apparatus. The last common theme is the self-regulatory balance between anatomical continuities and discontinuities of the endomembrane system. As this balance depends on secretory activity, it provides a source of morphological variability among cell types or, for a given cell type, according to environmental conditions. Beyond this first source of variability, it appears that divergent strategies pave the evolutionary routes in different eukaryotic kingdoms. These divergent strategies primarily affect the levels of stacking, of stabilization, and of clustering of the Golgi apparatus. They presumably underscore a trade-off between versatility and stability to adapt the secretory function to the degree of environmental variability. Nonequilibrium secretory structures would provide yeasts, and plants to a lesser extent, with the required versatility to cope with ever changing environments, by contrast to the stabler milieu intérieur of homeothermic animals.
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Affiliation(s)
- François Képès
- ATelier de Génomique Cognitive, CNRS UMR 8071/Genopole and Epigenomics Project, Genopole, Evry, France
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25
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Gobeil F, Bernier SG, Vazquez-Tello A, Brault S, Beauchamp MH, Quiniou C, Marrache AM, Checchin D, Sennlaub F, Hou X, Nader M, Bkaily G, Ribeiro-da-Silva A, Goetzl EJ, Chemtob S. Modulation of pro-inflammatory gene expression by nuclear lysophosphatidic acid receptor type-1. J Biol Chem 2003; 278:38875-83. [PMID: 12847111 DOI: 10.1074/jbc.m212481200] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Lysophosphatidic acid (LPA) is a bioactive molecule involved in inflammation, immunity, wound healing, and neoplasia. Its pleiotropic actions arise presumably by interaction with their cell surface G protein-coupled receptors. Herein, the presence of the specific nuclear lysophosphatidic acid receptor-1 (LPA1R) was revealed in unstimulated porcine cerebral microvascular endothelial cells (pCMVECs), LPA1R stably transfected HTC4 rat hepatoma cells, and rat liver tissue using complementary approaches, including radioligand binding experiments, electron- and cryomicroscopy, cell fractionation, and immunoblotting with three distinct antibodies. Coimmunoprecipitation studies in enriched plasmalemmal fractions of unstimulated pCMVEC showed that LPA1Rs are dually sequestrated in caveolin-1 and clathrin subcompartments, whereas in nuclear fractions LPA1R appeared primarily in caveolae. Immunofluorescent assays using a cell-free isolated nuclear system confirmed LPA1R and caveolin-1 co-localization. In pCMVEC, LPA-stimulated increases in cyclooxygenase-2 and inducible nitric-oxide synthase RNA and protein expression were insensitive to caveolea-disrupting agents but sensitive to LPA-generating phospholipase A2 enzyme and tyrosine kinase inhibitors. Moreover, LPA-induced increases in Ca2+ transients and/or iNOS expression in highly purified rat liver nuclei were prevented by pertussis toxin, phosphoinositide 3-kinase/Akt inhibitor wortmannin and Ca2+ chelator and channel blockers EGTA and SK&F96365, respectively. This study describes for the first time the nucleus as a potential organelle for LPA intracrine signaling in the regulation of pro-inflammatory gene expression.
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MESH Headings
- Androstadienes/pharmacology
- Animals
- Blotting, Western
- Calcium/metabolism
- Caveolin 1
- Caveolins/metabolism
- Cell Nucleus/metabolism
- Cell-Free System/metabolism
- Cells, Cultured
- Chelating Agents/pharmacology
- Clathrin/metabolism
- Egtazic Acid/pharmacology
- Endothelium, Vascular/cytology
- Enzyme Inhibitors/pharmacology
- Gene Expression Regulation
- Immunoblotting
- Liver/metabolism
- Microcirculation
- Microscopy, Electron
- Microscopy, Fluorescence
- Nitric Oxide Synthase/metabolism
- Nitric Oxide Synthase Type II
- Pertussis Toxin/pharmacology
- Phosphoinositide-3 Kinase Inhibitors
- Phospholipases A/metabolism
- Phospholipases A2
- Precipitin Tests
- Protein Binding
- Protein-Tyrosine Kinases/metabolism
- Rats
- Receptors, Cell Surface/metabolism
- Receptors, Cell Surface/physiology
- Receptors, G-Protein-Coupled
- Receptors, Lysophosphatidic Acid
- Subcellular Fractions/metabolism
- Swine
- Time Factors
- Transfection
- Tumor Cells, Cultured
- Wortmannin
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Affiliation(s)
- Fernand Gobeil
- Departments of Pediatrics, Ophthalmology and Pharmacology, Research Center of Hôpital Sainte-Justine, Montréal, Québec H3T 1C5, Canada.
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26
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Abstract
The ability of cells to synthesize and secrete proteins is essential for numerous cellular functions. Therefore, when mutations in one component of the secretory pathway result in a tissue-specific defect, a unique opportunity arises to examine the molecular mechanisms at play. The recent finding that a defect in the protein sedlin, whose yeast counterpart is involved in the first step of the secretory pathway, leads to a cartilage-specific disorder in humans raises numerous questions and interesting possibilities for understanding both the pathobiology involved and the role of membrane traffic in normal cartilage development.
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Affiliation(s)
- Michael Sacher
- Biotechnology Research Institute, 6100 Royalmount Avenue, Montreal, QC, Canada H4P 2R2.
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27
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Elsner M, Hashimoto H, Nilsson T. Cisternal maturation and vesicle transport: join the band wagon! (Review). Mol Membr Biol 2003; 20:221-9. [PMID: 12893530 DOI: 10.1080/0968768031000114024] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
'No cellular organelle has been the subject of as many, as long-lasting or as diverse polemics as the Golgi apparatus'. This statement was made by Whaley almost 30 years ago in the book The Golgi Apparatus and still holds true today, perhaps more then ever. Why is this? How come something as mundane as a series of intracellular membrane bound structures continues to fascinate and captivate a large section of the cell biology community? One simple reason (putting polemics aside) is that the secretory pathway appears deceptively simple. Once probed, however, it has a persistent habit of developing into an enigma. Is one then not closer than 30 years ago? In a sense yes, in that one has more components and a better understanding of inherent membrane dynamics, but it is still not known how newly synthesized proteins and lipids make their way from the ER to the plasma membrane. Is it by vesicles, cisternal carriers or transient tubular connections? It has also been learned that newly synthesized proteins are segregated away from the resident components throughout the pathway, but not how. Do coat proteins hold the key? It is understood that the cytoskeleton is important, but not really why. It is known that each Golgi stack is a fully functional unit, but not why stacks are connected laterally into a large ribbon (the Golgi apparatus). This review focuses on how proteins make their way through the pathway, a basic question that remains to be answered.
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Affiliation(s)
- Markus Elsner
- Cell Biology Programme, EMBL, Meyerhofstrasse 1, D-690117, Heidelberg, Germany
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28
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Tran K, Thorne-Tjomsland G, DeLong CJ, Cui Z, Shan J, Burton L, Jamieson JC, Yao Z. Intracellular assembly of very low density lipoproteins containing apolipoprotein B100 in rat hepatoma McA-RH7777 cells. J Biol Chem 2002; 277:31187-200. [PMID: 12065576 DOI: 10.1074/jbc.m200249200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies with McA-RH7777 cells showed a 15-20-min temporal delay in the oleate treatment-induced assembly of very low density lipoproteins (VLDL) after apolipoprotein (apo) B100 translation, suggesting a post-translational process. Here, we determined whether the post-translational assembly of apoB100-VLDL occurred within the endoplasmic reticulum (ER) or in post-ER compartments using biochemical and microscopic techniques. At steady state, apoB100 distributed throughout ER and Golgi, which were fractionated by Nycodenz gradient centrifugation. Pulse-chase experiments showed that it took about 20 min for newly synthesized apoB100 to exit the ER and to accumulate in the cis/medial Golgi. At the end of a subsequent 20-min chase, a small fraction of apoB100 accumulated in the distal Golgi, and a large amount of apoB100 was secreted into the medium as VLDL. VLDL was not detected either in the lumen of ER or in that of cis/medial Golgi where apoB100 was membrane-associated and sensitive to endoglycosidase H treatment. In contrast, VLDL particles were found in the lumen of the distal Golgi where apoB100 was resistant to endoglycosidase H. Formation of lumenal VLDL almost coincided with the appearance of VLDL in the medium, suggesting that the site of VLDL assembly is proximal to the site of secretion. When microsomal triglyceride transfer protein activity was inactivated after apoB had exited the ER, VLDL formation in the distal Golgi and its subsequent secretion was unaffected. Lipid analysis by tandem mass spectrometry showed that oleate treatment increased the masses of membrane phosphatidylcholine (by 68%) and phosphatidylethanolamine (by 27%) and altered the membrane phospholipid profiles of ER and Golgi. Taken together, these results suggest that VLDL assembly in McA-RH7777 cells takes place in compartments at the distal end of the secretory pathway.
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Affiliation(s)
- Khai Tran
- Lipoprotein & Atherosclerosis Group, University of Ottawa Heart Institute, Ottawa, Ontario K1Y 4W7, Canada
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29
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Abstract
Most models put forward to explain cellular processes do not stand the test of time. The 'lucky' few that are able to survive extensive experimental tests and peer critique may eventually become dogmas or paradigms. When this happens, the amount of experimental data required to overturn the paradigm is extensive. To some, such inertia may seem prohibitive to scientific progress but rather, in our opinion, this helps to maintain a degree of coherence. It is needed so that experiments and interpretations may be conducted within relatively safe boundaries. In the field of protein transport in the secretory pathway, we have enjoyed a relatively stable and productive period for quite some time (more than 30 years!). It is only very recently that the field has entered into a phase where all bets seem to be off. As in any paradigm shift, the accumulation of experimental observations inconsistent with the old dogma eventually reached a critical point. As we 'reluctantly' dispense with the long-standing paradigm of forward vesicular transport, we face a time that is bound to be trying as well as exciting.
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Affiliation(s)
- Brian Storrie
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0308, USA.
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30
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Zhao X, Lasell TKR, Melançon P. Localization of large ADP-ribosylation factor-guanine nucleotide exchange factors to different Golgi compartments: evidence for distinct functions in protein traffic. Mol Biol Cell 2002; 13:119-33. [PMID: 11809827 PMCID: PMC65077 DOI: 10.1091/mbc.01-08-0420] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Activation of several ADP-ribosylation factors (ARFs) by guanine nucleotide exchange factors (GEFs) regulates recruitment of coat proteins (COPs) on the Golgi complex and is generally assumed to be the target of brefeldin A (BFA). The large ARF-GEFs Golgi-specific BFA resistance factor 1 (GBF1) and BFA-inhibited GEFs (BIGs) localize to this organelle but catalyze exchange preferentially on class II and class I ARFs, respectively. We now demonstrate using quantitative confocal microscopy that these GEFs show a very limited overlap with each other (15 and 23%). In contrast, GBF1 colocalizes with the cis-marker p115 (86%), whereas BIGs overlap extensively with TGN38 (83%). Consistent with these distributions, GBF1, but not BIG1, partially relocalized to peripheral sites after incubation at 15 degrees C. The new GBF1 structures represent peripheral vesicular tubular clusters (VTCs) because 88% of structures analyzed stained for both GBF1 and p115. Furthermore, as expected of VTCs, they rapidly reclustered to the Golgi complex in a microtubule-dependent manner upon warm-up. These observations suggest that GBF1 and BIGs activate distinct subclasses of ARFs in specific locations to regulate different types of reactions. In agreement with this possibility, COPI overlapped to a greater extent with GBF1 (64%) than BIG1 (31%), whereas clathrin showed limited overlap with BIG1, and virtually none with GBF1.
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Affiliation(s)
- Xinhua Zhao
- Department of Cell Biology, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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31
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Martinez-Menárguez JA, Prekeris R, Oorschot VM, Scheller R, Slot JW, Geuze HJ, Klumperman J. Peri-Golgi vesicles contain retrograde but not anterograde proteins consistent with the cisternal progression model of intra-Golgi transport. J Cell Biol 2001; 155:1213-24. [PMID: 11748250 PMCID: PMC2199342 DOI: 10.1083/jcb.200108029] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A cisternal progression mode of intra-Golgi transport requires that Golgi resident proteins recycle by peri-Golgi vesicles, whereas the alternative model of vesicular transport predicts anterograde cargo proteins to be present in such vesicles. We have used quantitative immuno-EM on NRK cells to distinguish peri-Golgi vesicles from other vesicles in the Golgi region. We found significant levels of the Golgi resident enzyme mannosidase II and the transport machinery proteins giantin, KDEL-receptor, and rBet1 in coatomer protein I-coated cisternal rims and peri-Golgi vesicles. By contrast, when cells expressed vesicular stomatitis virus protein G this anterograde marker was largely absent from the peri-Golgi vesicles. These data suggest a role of peri-Golgi vesicles in recycling of Golgi residents, rather than an important role in anterograde transport.
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Affiliation(s)
- J A Martinez-Menárguez
- Department of Cell Biology, School of Medicine, University of Murcia, 30071 Murcia, Spain
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32
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Mironov AA, Beznoussenko GV, Nicoziani P, Martella O, Trucco A, Kweon HS, Di Giandomenico D, Polishchuk RS, Fusella A, Lupetti P, Berger EG, Geerts WJ, Koster AJ, Burger KN, Luini A. Small cargo proteins and large aggregates can traverse the Golgi by a common mechanism without leaving the lumen of cisternae. J Cell Biol 2001; 155:1225-38. [PMID: 11756473 PMCID: PMC2199327 DOI: 10.1083/jcb.200108073] [Citation(s) in RCA: 165] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Procollagen (PC)-I aggregates transit through the Golgi complex without leaving the lumen of Golgi cisternae. Based on this evidence, we have proposed that PC-I is transported across the Golgi stacks by the cisternal maturation process. However, most secretory cargoes are small, freely diffusing proteins, thus raising the issue whether they move by a transport mechanism different than that used by PC-I. To address this question we have developed procedures to compare the transport of a small protein, the G protein of the vesicular stomatitis virus (VSVG), with that of the much larger PC-I aggregates in the same cell. Transport was followed using a combination of video and EM, providing high resolution in time and space. Our results reveal that PC-I aggregates and VSVG move synchronously through the Golgi at indistinguishable rapid rates. Additionally, not only PC-I aggregates (as confirmed by ultrarapid cryofixation), but also VSVG, can traverse the stack without leaving the cisternal lumen and without entering Golgi vesicles in functionally relevant amounts. Our findings indicate that a common mechanism independent of anterograde dissociative carriers is responsible for the traffic of small and large secretory cargo across the Golgi stack.
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Affiliation(s)
- A A Mironov
- Department of Cell Biology and Oncology, Istituto di Ricerche Farmacologiche "Mario Negri," 66030 Santa Maria Imbaro, Chieti, Italy
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33
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Abstract
The role of vesicles in cargo transport through the Golgi apparatus has been controversial. Large forms of cargo such as protein aggregates are thought to progress through the Golgi stack by a process of cisternal maturation, balanced by a return flow of Golgi resident proteins in COPI-coated vesicles. However, whether this is the primary role of vesicles, or whether they also serve to transport small cargo molecules in a forward direction has been debated. Two papers (Martínez-Menárguez et al., 2001; Mironov et al., 2001, this issue) use sophisticated light and electron microscopy to provide evidence that the vesicular stomatitis virus membrane glycoprotein (VSV G)* is largely excluded from vesicles in vivo, and does not move between cisternae, whereas resident Golgi enzymes freely enter vesicles as predicted by the cisternal maturation model. Both papers conclude that vesicles are likely to play only a minor role in the anterograde transport of cargo through the Golgi apparatus in mammalian tissue culture cells.
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Affiliation(s)
- H R Pelham
- Laboratory of Molecular Biology, Medical Research Council, Hills Road, Cambridge CB2 2QH, UK.
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34
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Sakata N, Phillips TE, Dixon JL. Distribution, transport, and degradation of apolipoprotein B-100 in HepG2 cells. J Lipid Res 2001. [DOI: 10.1016/s0022-2275(20)31523-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Ho YY, Deckelbaum RJ, Chen Y, Vogel T, Talmage DA. Apolipoprotein E inhibits serum-stimulated cell proliferation and enhances serum-independent cell proliferation. J Biol Chem 2001; 276:43455-62. [PMID: 11551921 DOI: 10.1074/jbc.m105325200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Independently of its role in lipid homeostasis, apolipoprotein E (apoE) inhibits cell proliferation. We compared the effects of apoE added to media (exogenous apoE) with the effects of stably expressed apoE (endogenous apoE) on cell proliferation. Exogenous and endogenous apoE increased population doubling times by 30-50% over a period of 14 days by prolonging the G(1) phase of the cell cycle. Exogenous and endogenous apoE also decreased serum-stimulated DNA synthesis by 30-50%. However, apoE did not cause cell cycle arrest; both apoE-treated and control cells achieved equivalent saturation densities at 14 days. Further analyses demonstrated that exogenous and endogenous apoE prevented activation of MAPK but not induction of c-fos expression in response to serum growth factors. Endogenous (but not exogenous) apoE altered serum concentration-dependent effects on proliferation. Whereas control (non-apoE-expressing) cell numbers increased with increasing serum concentrations (1.6-fold for every 2-fold increase in serum), apoE-expressing cell numbers did not differ as serum levels were raised from 2.5 to 10%. In addition, in low serum (0.1%), apoE-expressing cells had elevated DNA synthesis levels compared with control cells. We conclude that apoE does not simply inhibit cell proliferation; rather, the presence of apoE alters the response to and requirement for serum mitogens.
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Affiliation(s)
- Y Y Ho
- Institute of Human Nutrition and the Department of Pediatrics, Columbia University, New York, New York 10032, USA
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36
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Oprins A, Rabouille C, Posthuma G, Klumperman J, Geuze HJ, Slot JW. The ER to Golgi interface is the major concentration site of secretory proteins in the exocrine pancreatic cell. Traffic 2001; 2:831-8. [PMID: 11733050 DOI: 10.1034/j.1600-0854.2001.21112.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
By using quantitative immuno-electron microscopy of two-sided labeled resin sections of rat exocrine pancreatic cells, we have established the relative concentrations of the secretory proteins amylase and chymotrypsinogen in the compartments of the secretory pathway. Their total concentration over the entire pathway was approximately 11 and approximately 460 times, respectively. Both proteins exhibited their largest increase in concentration between the endoplasmic reticulum and cis-Golgi, where they were concentrated 3-4 and 50-70 times, respectively. Over the further pathway, increases in concentration were moderate, albeit two times higher for chymotrypsinogen than for amylase. From trans-Golgi to secretory granules, where the main secretory protein concentration is often thought to occur, relatively small concentration increases were observed. Additional observations on a third secretory protein, procarboxypeptidase A, showed a concentration profile very similar to chymotrypsinogen. The relatively high concentration of amylase in the early compartments of the secretory route is consistent with its exceptionally slow intracellular transport. Our data demonstrate that secretory proteins undergo their main concentration between the endoplasmic reticulum and cis-Golgi, where we have previously found concentration activity associated with vesicular tubular clusters (Martínez-Menárguez JA, Geuze HJ, Slot JW, Klumperman J. Cell 1999; 98: 81-90).
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Affiliation(s)
- A Oprins
- Department of Cell Biology, University Medical Center Utrecht, Institute for Biomembranes and Center for Biomedical Genetics, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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37
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Abstract
During interphase the transport of material between different intracellular organelles requires accurate regulation of fusiogenic domains. Recent studies on hepatic endosomes indicated that compartmentalized Cdk2 cyclin E complexes act by braking fusion events. These Cdk2 complexes integrate tyrosine phosphorylation and dephosphory lation inputs, resulting in the control of the number of rounds of fusion at discrete domains. This leads to changes in the intracellular location of internalized receptors and ultimately their biological response.Key words: vesicular traffic, Cdk2, receptors tyrosine kinases.
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38
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Burgess JW, Marcel YL. Dynamic and stable pools of apoE differ functionally at the HepG2 cell surface. J Lipid Res 2001. [DOI: 10.1016/s0022-2275(20)30273-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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39
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Ying M, Flatmark T, Saraste J. The p58-positive pre-golgi intermediates consist of distinct subpopulations of particles that show differential binding of COPI and COPII coats and contain vacuolar H(+)-ATPase. J Cell Sci 2000; 113 ( Pt 20):3623-38. [PMID: 11017878 DOI: 10.1242/jcs.113.20.3623] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have studied the structural and functional properties of the pre-Golgi intermediate compartment (IC) in normal rat kidney cells using analytical cell fractionation with p58 as the principal marker. The sedimentation profile (sediterm) of p58, obtained by analytical differential centrifugation, revealed in steady-state cells the presence of two main populations of IC elements whose average sedimentation coefficients, s(H)=1150+/-58S (‘heavy’) and s(L)=158+/-8S (‘light’), differed from the s-values obtained for elements of the rough and smooth endoplasmic reticulum. High resolution analysis of these subpopulations in equilibrium density gradients further revealed that the large difference in their s-values was mainly due to particle size. The ‘light’ particle population contained the bulk of COPI and COPII coats, and redistribution of p58 to these particles was observed in transport-arrested cells, showing that the two types of elements are also compositionally distinct and have functional counterparts in intact cells. Using a specific antibody against the 16 kDa proteolipid subunit of the vacuolar H(+)-ATPase, an enrichment of the V(o)domain of the ATPase was observed in the p58-positive IC elements. Interestingly, these elements could contain both COPI and COPII coats and their density distribution was markedly affected by GTP(γ)S. Together with morphological observations, these results demonstrate that, in addition to clusters of small tubules and vesicles, the IC also consists of large-sized structures and corroborate the proposal that the IC elements contain an active vacuolar H(+)-ATPase.
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Affiliation(s)
- M Ying
- Departments of Biochemistry and Molecular Biology and Anatomy and Cell Biology, University of Bergen, Norway
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40
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Maugeais C, Tietge UJ, Tsukamoto K, Glick JM, Rader DJ. Hepatic apolipoprotein E expression promotes very low density lipoprotein-apolipoprotein B production in vivo in mice. J Lipid Res 2000. [DOI: 10.1016/s0022-2275(20)32001-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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41
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Volchuk A, Amherdt M, Ravazzola M, Brügger B, Rivera VM, Clackson T, Perrelet A, Söllner TH, Rothman JE, Orci L. Megavesicles implicated in the rapid transport of intracisternal aggregates across the Golgi stack. Cell 2000; 102:335-48. [PMID: 10975524 DOI: 10.1016/s0092-8674(00)00039-8] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Engineered protein aggregates ranging up to 400 nm in diameter were selectively deposited within the cis-most cisternae of the Golgi stack following a 15 degrees C block. These aggregates are much larger than the standard volume of Golgi vesicles, yet they are transported across the stack within 10 min after warming the cells to 20 degrees C. Serial sectioning reveals that during the peak of anterograde transport, about 20% of the aggregates were enclosed in topologically free "megavesicles" which appear to pinch off from the rims of the cisternae. These megavesicles can explain the rapid transport of aggregates without cisternal progression on this time scale.
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Affiliation(s)
- A Volchuk
- Cellular Biochemistry & Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA
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42
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Roy L, Bergeron JJ, Lavoie C, Hendriks R, Gushue J, Fazel A, Pelletier A, Morré DJ, Subramaniam VN, Hong W, Paiement J. Role of p97 and syntaxin 5 in the assembly of transitional endoplasmic reticulum. Mol Biol Cell 2000; 11:2529-42. [PMID: 10930451 PMCID: PMC14937 DOI: 10.1091/mbc.11.8.2529] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Transitional endoplasmic reticulum (tER) consists of confluent rough and smooth endoplasmic reticulum (ER) domains. In a cell-free incubation system, low-density microsomes (1.17 g cc(-1)) isolated from rat liver homogenates reconstitute tER by Mg(2+)GTP- and Mg(2+)ATP-hydrolysis-dependent membrane fusion. The ATPases associated with different cellular activities protein p97 has been identified as the relevant ATPase. The ATP depletion by hexokinase or treatment with either N-ethylmaleimide or anti-p97 prevented assembly of the smooth ER domain of tER. High-salt washing of low-density microsomes inhibited assembly of the smooth ER domain of tER, whereas the readdition of purified p97 with associated p47 promoted reconstitution. The t-SNARE syntaxin 5 was observed within the smooth ER domain of tER, and antisyntaxin 5 abrogated formation of this same membrane compartment. Thus, p97 and syntaxin 5 regulate assembly of the smooth ER domain of tER and hence one of the earliest membrane differentiated components of the secretory pathway.
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Affiliation(s)
- L Roy
- Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Québec, Canada
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43
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Abstract
Investigators are revisiting basic concepts of the structure-function relationships of the Golgi apparatus. A key issue is the properties of the transport carriers that operate within the secretory pathway. Golgi morphology and dynamics differ between species but data from various model systems are pointing toward an integrated view of Golgi organization.
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Affiliation(s)
- B S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, 60637, USA.
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44
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Ho YY, Al-Haideri M, Mazzone T, Vogel T, Presley JF, Sturley SL, Deckelbaum RJ. Endogenously expressed apolipoprotein E has different effects on cell lipid metabolism as compared to exogenous apolipoprotein E carried on triglyceride-rich particles. Biochemistry 2000; 39:4746-54. [PMID: 10769131 DOI: 10.1021/bi992294a] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Apolipoprotein E (apoE) on model triglyceride-rich particles (TGRP) increases triglyceride (TG) utilization and cholesteryl ester (CE) hydrolysis, independent of its effect on enhancing particle uptake. We questioned whether, under physiological concentrations, endogenously expressed apoE has similar effects on cellular lipid metabolism as compared to exogenous apoE. J774 macrophages, which do not express apoE, were engineered to express endogenous apoE by transfection of human apoE3 cDNA expression constructs (E(+)) or control vectors (E(-)) into the cells. To compare the effects of exogenous apoE and endogenous apoE on TGRP uptake, cells were incubated with or without apoE associated with (3)H-cholesteryl ether-labeled TGRP. Exogenous apoE enhanced TGRP uptake in both E(-) and E(+) cells. E(-) cells displayed significantly higher TGRP uptake than E(+) cells. Sodium chlorate, which inhibits cell proteoglycan synthesis, markedly diminished differences in TGRP uptake between E(-) and E(+) cells, suggesting that endogenous apoE-proteoglycan interaction contributes to differences in uptake between the two cell types. Particle uptake by the LDL receptor, by the LDL receptor related protein, or by scavenger receptors were similar between E(-) and E(+) cells indicating that endogenous apoE expression does not have a general effect on endocytic pathways. Exogenous apoE carried on TGRP stimulated TG utilization and CE hydrolysis in both cell types. However, TG utilization and CE hydrolysis were not affected by endogenous apoE expression. In conclusion, macrophage expression of apoE has very different effects on TGRP metabolism than exogenously supplied apoE. The fluorescence microscopy results in this study showing that exogenous apoE and endogenous apoE were confined in separate cellular compartments support the hypothesis that these differences resulted from distinct intracellular trafficking pathways followed by exogenous apoE bound to TGRP as compared to endogenous cell-expressed apoE.
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Affiliation(s)
- Y Y Ho
- Department of Pediatrics, Institute of Human Nutrition, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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45
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Rensen PC, Jong MC, van Vark LC, van der Boom H, Hendriks WL, van Berkel TJ, Biessen EA, Havekes LM. Apolipoprotein E is resistant to intracellular degradation in vitro and in vivo. Evidence for retroendocytosis. J Biol Chem 2000; 275:8564-71. [PMID: 10722695 DOI: 10.1074/jbc.275.12.8564] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Apolipoprotein E (apoE) is an important determinant for the uptake of triglyceride-rich lipoproteins and emulsions by the liver, but the intracellular pathway of apoE following particle internalization is poorly defined. In the present study, we investigated whether retroendocytosis is a unique feature of apoE as compared with apoB by studying the intracellular fate of very low density lipoprotein-sized apoE-containing triglyceride-rich emulsion particles and LDL after LDLr-mediated uptake. Incubation of HepG2 cells with [(3)H]cholesteryl oleate-labeled particles at 37 degrees C led to a rapid release of [(3)H]cholesterol within 30 min for both LDL and emulsion particles. In contrast, emulsion-derived (125)I-apoE was more resistant to degradation (>/=120 min) than LDL-derived (125)I-apoB (30 min). Incubation at 18 degrees C, which allows endosomal uptake but prevents lysosomal degradation, with subsequent incubation at 37 degrees C resulted in a time-dependent release of intact apoE from the cells (up to 14% of the endocytosed apoE at 4 h). The release of apoE was accelerated by the presence of protein-free emulsion (20%) or high density lipoprotein (26%). Retroendocytosis of intact particles could be excluded since little intact [(3)H]cholesteryl oleate was released (<3%). In contrast, the degradation of LDL was complete with virtually no secretion of intact apoB into the medium. The intracellular stability of apoE was also demonstrated after hepatic uptake in C57Bl/6 mice. Intravenous injection of (125)I-apoE and [(3)H]cholesteryl oleate-labeled emulsions resulted in efficient LDLr-mediated uptake of both components by the liver (45-50% of the injected dose after 20 min). At 1 h after injection, only 15-20% of the hepatic (125)I-apoE was degraded, whereas 75% of the [(3)H]cholesteryl oleate was hydrolyzed. From these data we conclude that following LDLr-mediated internalization by liver cells, apoE can escape degradation and can be resecreted. This sequence of events may allow apoE to participate in its hypothesized intracellular functions such as mediator of the post-lysosomal trafficking of lipids and very low density lipoprotein assembly.
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Affiliation(s)
- P C Rensen
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, University of Leiden, Sylvius Laboratory, P. O. Box 9503, 2300 RA Leiden, The Netherlands.
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46
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Chevet E, Lemaître G, Cailleret K, Dahan S, Bergeron JJ, Katinka MD. Identification and characterization of an intracellular protein complex that binds fibroblast growth factor-2 in bovine brain. Biochem J 1999; 341 ( Pt 3):713-23. [PMID: 10417336 PMCID: PMC1220410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
The fibroblast growth factor (FGF) family is composed of polypeptides with sequence identity which signal through transmembrane tyrosine kinase receptors. We report here the purification from bovine brain microsomes of an FGF-2-binding complex composed of three proteins of apparent molecular masses 150 kDa, 79 kDa and 46 kDa. Only the 150 kDa and 79 kDa proteins bound FGF-2 in cross-linking and ligand-blotting experiments. Binding of FGF-2 to p79 is enhanced in the presence of calcium. Peptide sequences allowed the identification of p150 and the cloning of the cDNAs encoding p79 and p46. The deduced amino acid sequence of p79 reveals high similarity to those of gastrin-binding protein and mitochondrial enoyl-CoA hydratase/hydroxyacyl-CoA dehydrogenase. p46 is similar to mitochondrial ketoacyl-CoA thiolase. Stable transfection of FR3T3 rat fibroblast cells with p79 cDNA analysed by electron microscopy following immunolabelling of ultra-thin cryosections revealed a localization of p79 in the secretory pathway, mainly in the endoplasmic reticulum and the Golgi region, where it is specifically associated with the molecular chaperone calnexin. In vivo a protein similar to the Golgi protein MG-160 forms a complex with FGF-2 and p79.
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Affiliation(s)
- E Chevet
- UER de Science, Université Paris XII, 61 avenue du Général De Gaulle, 94010 Créteil Cédex, France
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47
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Holwell TA, Schweitzer SC, Reyland ME, Evansk RM. Vimentin-dependent utilization of LDL-cholesterol in human adrenal tumor cells is not associated with the level of expression of apoE, sterol carrier protein-2, or caveolin. J Lipid Res 1999. [DOI: 10.1016/s0022-2275(20)33386-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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48
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Lavoie C, Paiement J, Dominguez M, Roy L, Dahan S, Gushue J, Bergeron J. Roles for alpha(2)p24 and COPI in endoplasmic reticulum cargo exit site formation. J Cell Biol 1999; 146:285-99. [PMID: 10427085 PMCID: PMC3206572 DOI: 10.1083/jcb.146.2.285] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
A two-step reconstitution system for the generation of ER cargo exit sites from starting ER-derived low density microsomes (LDMs; 1.17 g/cc) is described. The first step is mediated by the hydrolysis of Mg(2+)ATP and Mg(2+)GTP, leading to the formation of a transitional ER (tER) with the soluble cargo albumin, transferrin, and the ER-to-Golgi recycling membrane proteins alpha(2)p24 and p58 (ERGIC-53, ER-Golgi intermediate compartment protein) enriched therein. Upon further incubation (step two) with cytosol and mixed nucleotides, interconnecting smooth ER tubules within tER transforms into vesicular tubular clusters (VTCs). The cytosolic domain of alpha(2)p24 and cytosolic COPI coatomer affect VTC formation. This is deduced from the effect of antibodies to the COOH-terminal tail of alpha(2)p24, but not of antibodies to the COOH-terminal tail of calnexin on this reconstitution, as well as the demonstrated recruitment of COPI coatomer to VTCs, its augmentation by GTPgammaS, inhibition by Brefeldin A (BFA), or depletion of beta-COP from cytosol. Therefore, the p24 family member, alpha(2)p24, and its cytosolic coat ligand, COPI coatomer, play a role in the de novo formation of VTCs and the generation of ER cargo exit sites.
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Affiliation(s)
- C. Lavoie
- Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Québec, Canada H3C 3J7
| | - J. Paiement
- Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Québec, Canada H3C 3J7
| | - M. Dominguez
- Department of Anatomy and Cell Biology, McGill University, Québec, Canada H3A 2B2
| | - L. Roy
- Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Québec, Canada H3C 3J7
| | - S. Dahan
- Department of Anatomy and Cell Biology, McGill University, Québec, Canada H3A 2B2
| | - J.N. Gushue
- Department of Anatomy and Cell Biology, McGill University, Québec, Canada H3A 2B2
| | - J.J.M. Bergeron
- Department of Anatomy and Cell Biology, McGill University, Québec, Canada H3A 2B2
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49
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Claude A, Zhao BP, Kuziemsky CE, Dahan S, Berger SJ, Yan JP, Armold AD, Sullivan EM, Melançon P. Gbf1. J Cell Biol 1999. [DOI: 10.1083/jcb.146.1.71] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Expression cloning from a cDNA library prepared from a mutant CHO cell line with Golgi-specific resistance to Brefeldin A (BFA) identified a novel 206-kD protein with a Sec7 domain termed GBF1 for Golgi BFA resistance factor 1. Overexpression of GBF1 allowed transfected cells to maintain normal Golgi morphology and grow in the presence of BFA. Golgi- enriched membrane fractions from such transfected cells displayed normal levels of ADP ribosylation factors (ARFs) activation and coat protein recruitment that were, however, BFA resistant. Hexahistidine-tagged–GBF1 exhibited BFA-resistant guanine nucleotide exchange activity that appears specific towards ARF5 at physiological Mg2+concentration. Characterization of cDNAs recovered from the mutant and wild-type parental lines established that transcripts in these cells had identical sequence and, therefore, that GBF1 was naturally BFA resistant. GBF1 was primarily cytosolic but a significant pool colocalized to a perinuclear structure with the β-subunit of COPI. Immunogold labeling showed highest density of GBF1 over Golgi cisternae and significant labeling over pleiomorphic smooth vesiculotubular structures. The BFA-resistant nature of GBF1 suggests involvement in retrograde traffic.
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Affiliation(s)
- Alejandro Claude
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Bao-Ping Zhao
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Craig E. Kuziemsky
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
| | - Sophie Dahan
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada, H3A 2B2
| | - Scott J. Berger
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| | - Jian-Ping Yan
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| | - Adrian D. Armold
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| | - Eric M. Sullivan
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| | - Paul Melançon
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
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50
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Claude A, Zhao BP, Kuziemsky CE, Dahan S, Berger SJ, Yan JP, Armold AD, Sullivan EM, Melançon P. GBF1: A novel Golgi-associated BFA-resistant guanine nucleotide exchange factor that displays specificity for ADP-ribosylation factor 5. J Cell Biol 1999; 146:71-84. [PMID: 10402461 PMCID: PMC2199737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Expression cloning from a cDNA library prepared from a mutant CHO cell line with Golgi-specific resistance to Brefeldin A (BFA) identified a novel 206-kD protein with a Sec7 domain termed GBF1 for Golgi BFA resistance factor 1. Overexpression of GBF1 allowed transfected cells to maintain normal Golgi morphology and grow in the presence of BFA. Golgi- enriched membrane fractions from such transfected cells displayed normal levels of ADP ribosylation factors (ARFs) activation and coat protein recruitment that were, however, BFA resistant. Hexahistidine-tagged-GBF1 exhibited BFA-resistant guanine nucleotide exchange activity that appears specific towards ARF5 at physiological Mg2+concentration. Characterization of cDNAs recovered from the mutant and wild-type parental lines established that transcripts in these cells had identical sequence and, therefore, that GBF1 was naturally BFA resistant. GBF1 was primarily cytosolic but a significant pool colocalized to a perinuclear structure with the beta-subunit of COPI. Immunogold labeling showed highest density of GBF1 over Golgi cisternae and significant labeling over pleiomorphic smooth vesiculotubular structures. The BFA-resistant nature of GBF1 suggests involvement in retrograde traffic.
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Affiliation(s)
- A Claude
- Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada, T6G 2H7
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