ERGIC-53 and traffic in the secretory pathway

2000 ◽  
Vol 113 (4) ◽  
pp. 587-596 ◽  
Author(s):  
H.P. Hauri ◽  
F. Kappeler ◽  
H. Andersson ◽  
C. Appenzeller
Keyword(s):  
Cystic Fibrosis ◽  
Protein Trafficking ◽  
Cell Biology ◽  
Secretory Pathway ◽  
Viral Infections ◽  
Cultured Cells ◽  
Intermediate Compartment ◽  
Retrograde Traffic ◽  
Specific Membrane ◽  
Transport Receptor

The ER-Golgi intermediate compartment (ERGIC) marker ERGIC-53 is a mannose-specific membrane lectin operating as a cargo receptor for the transport of glycoproteins from the ER to the ERGIC. Lack of functional ERGIC-53 leads to a selective defect in secretion of glycoproteins in cultured cells and to hemophilia in humans. Beyond its interest as a transport receptor, ERGIC-53 is an attractive probe for studying numerous aspects of protein trafficking in the secretory pathway, including traffic routes, mechanisms of anterograde and retrograde traffic, retention of proteins in the ER, and the function of the ERGIC. Understanding these fundamental processes of cell biology will be crucial for the elucidation and treatment of many inherited and acquired diseases, such as cystic fibrosis, Alzheimer's disease and viral infections.

scholarly journals The pivotal role of ERp44 in patrolling protein secretion

2020 ◽  
Vol 133 (21) ◽  
pp. jcs240366
Author(s):  
Tiziana Tempio ◽  
Tiziana Anelli
Keyword(s):  
Quality Control ◽  
Membrane Trafficking ◽  
Cell Biology ◽  
Secretory Pathway ◽  
Oligomeric Proteins ◽  
Protein Ligands ◽  
Intermediate Compartment ◽  
Definition Of ◽  
Main Language

ABSTRACTInteractions between protein ligands and receptors are the main language of intercellular communication; hence, how cells select proteins to be secreted or presented on the plasma membrane is a central concern in cell biology. A series of checkpoints are located along the secretory pathway, which ensure the fidelity of such protein signals (quality control). Proteins that pass the checkpoints operated in the endoplasmic reticulum (ER) by the binding immunoglobulin protein (BiP; also known as HSPA5 and GRP78) and the calnexin–calreticulin systems, must still overcome additional scrutiny in the ER-Golgi intermediate compartment (ERGIC) and the Golgi. One of the main players of this process in all metazoans is the ER-resident protein 44 (ERp44); by cycling between the ER and the Golgi, ERp44 controls the localization of key enzymes designed to act in the ER but that are devoid of suitable localization motifs. ERp44 also patrols the secretion of correctly assembled disulfide-linked oligomeric proteins. Here, we discuss the mechanisms driving ERp44 substrate recognition, with important consequences on the definition of ‘thiol-mediated quality control’. We also describe how pH and zinc gradients regulate the functional cycle of ERp44, coupling quality control and membrane trafficking along the early secretory compartment.

Cultured epithelial cells derived from human foetal pancreas as a model for the study of cystic fibrosis: further analyses on the origins and nature of the cell types

1988 ◽  
Vol 90 (1) ◽  
pp. 73-77
Author(s):  
A. Harris ◽  
L. Coleman
Keyword(s):  
Cystic Fibrosis ◽  
Tissue Culture ◽  
Epithelial Cells ◽  
Culture System ◽  
Cultured Cells ◽  
Cell Types ◽  
Cultured Epithelial Cells ◽  
Different Cell Types ◽  
Foetal Pancreas

The establishment of a tissue-culture system for epithelial cells derived from human foetal pancreas has recently been reported. Further analyses have now been made on these cells in vitro, together with parallel investigation of the distribution of different cell types within the intact foetal pancreas. Results support the view that the cultured cells are ductal in origin and nature. Pancreatic epithelial cell cultures have also been established from foetuses with cystic fibrosis.

scholarly journals Regulating Intracellular Antiviral Defense and Permissiveness to Hepatitis C Virus RNA Replication through a Cellular RNA Helicase, RIG-I

2005 ◽  
Vol 79 (5) ◽  
pp. 2689-2699 ◽  
Author(s):  
Rhea Sumpter ◽  
Yueh-Ming Loo ◽  
Eileen Foy ◽  
Kui Li ◽  
Mitsutoshi Yoneyama ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Viral Infections ◽  
Cultured Cells ◽  
Rna Replication ◽  
Rna Helicase ◽  
Hcv Rna ◽  
Helicase Domain ◽  
Replication Studies ◽  
Virus Rna

ABSTRACT Virus-responsive signaling pathways that induce alpha/beta interferon production and engage intracellular immune defenses influence the outcome of many viral infections. The processes that trigger these defenses and their effect upon host permissiveness for specific viral pathogens are not well understood. We show that structured hepatitis C virus (HCV) genomic RNA activates interferon regulatory factor 3 (IRF3), thereby inducing interferon in cultured cells. This response is absent in cells selected for permissiveness for HCV RNA replication. Studies including genetic complementation revealed that permissiveness is due to mutational inactivation of RIG-I, an interferon-inducible cellular DExD/H box RNA helicase. Its helicase domain binds HCV RNA and transduces the activation signal for IRF3 by its caspase recruiting domain homolog. RIG-I is thus a pathogen receptor that regulates cellular permissiveness to HCV replication and, as an interferon-responsive gene, may play a key role in interferon-based therapies for the treatment of HCV infection.

Cystic Fibrosis as a Theme to Incorporate Team-Based Learning in Cell Biology Courses

2018 ◽  
Vol 80 (1) ◽  
pp. 2-5
Author(s):  
Jennifer Hurst-Kennedy
Keyword(s):  
Cystic Fibrosis ◽  
High School Students ◽  
Cell Biology ◽  
Class Group ◽  
Teaching Strategy ◽  
School Students ◽  
Group Problem ◽  
Video Viewing ◽  
Team Based Learning ◽  
Upper Level

Team-based learning (TBL) is structured, cooperative learning teaching strategy used in a variety of disciplines. TBL uses a three-step approach for delivering content to students: out-of-class preparation, readiness assurance, and application. In this article, a method for incorporating TBL into an undergraduate cell biology course using cystic fibrosis (CF) as a theme is described. Class content is divided into modules. Each module consists of (1) out-of-class video viewing and reading assignments; (2) individual and team assessments, mini-lectures, and think-pair-share activities to assess understanding of the material; and (3) in-class, group problem sets related to the molecular pathogenesis of CF. Although originally designed for an introductory undergraduate cell biology course, this curriculum can be easily adapted for upper-level undergraduate and high school students.

scholarly journals The Basolateral Polarity Module Promotes Slit Diaphragm Formation in Drosophila Nephrocytes, a Model of Vertebrate Podocytes

2021 ◽  
pp. ASN.2020071050
Author(s):  
Michael Mysh ◽  
John S. Poulton
Keyword(s):  
Nephrotic Syndrome ◽  
Protein Trafficking ◽  
Cell Biology ◽  
Genetic Interaction ◽  
Intercellular Junctions ◽  
Protein Distribution ◽  
Genetic Manipulations ◽  
Apicobasal Polarity ◽  
Apical Polarity ◽  
Polarity Proteins

BackgroundPodocyte slit diaphragms (SDs) are intercellular junctions that function as size-selective filters, excluding most proteins from urine. Abnormalities in SDs cause proteinuria and nephrotic syndrome. Podocytes exhibit apicobasal polarity, which can affect fundamental aspects of cell biology, including morphology, intercellular junction formation, and asymmetric protein distribution along the plasma membrane. Apical polarity protein mutations cause nephrotic syndrome, and data suggest apical polarity proteins regulate SD formation. However, there is no evidence that basolateral polarity proteins regulate SDs. Thus, the role of apicobasal polarity in podocytes remains unclear.MethodsGenetic manipulations and transgenic reporters determined the effects of disrupting apicobasal polarity proteins in Drosophila nephrocytes, which have SDs similar to those of mammalian podocytes. Confocal and electron microscopy were used to characterize SD integrity after loss of basolateral polarity proteins, and genetic-interaction studies illuminated relationships among apicobasal polarity proteins.ResultsThe study identified four novel regulators of nephrocyte SDs: Dlg, Lgl, Scrib, and Par-1. These proteins comprise the basolateral polarity module and its effector kinase. The data suggest these proteins work together, with apical polarity proteins, to regulate SDs by promoting normal endocytosis and trafficking of SD proteins.ConclusionsGiven the recognized importance of apical polarity proteins and SD protein trafficking in podocytopathies, the findings connecting basolateral polarity proteins to these processes significantly advance our understanding of SD regulation.

scholarly journals Amyloid-like aggregating proteins cause lysosomal defects in neurons via gain-of-function toxicity

2021 ◽  
Vol 5 (3) ◽  
pp. e202101185
Author(s):  
Irene Riera-Tur ◽  
Tillman Schäfer ◽  
Daniel Hornburg ◽  
Archana Mishra ◽  
Miguel da Silva Padilha ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Protein Trafficking ◽  
Cell Biology ◽  
Electron Tomography ◽  
Lysosomal Storage ◽  
Gain Of Function ◽  
Cryo Electron Tomography ◽  
A Subunit ◽  
Late Stages ◽  
Β Sheet

The autophagy-lysosomal pathway is impaired in many neurodegenerative diseases characterized by protein aggregation, but the link between aggregation and lysosomal dysfunction remains poorly understood. Here, we combine cryo-electron tomography, proteomics, and cell biology studies to investigate the effects of protein aggregates in primary neurons. We use artificial amyloid-like β-sheet proteins (β proteins) to focus on the gain-of-function aspect of aggregation. These proteins form fibrillar aggregates and cause neurotoxicity. We show that late stages of autophagy are impaired by the aggregates, resulting in lysosomal alterations reminiscent of lysosomal storage disorders. Mechanistically, β proteins interact with and sequester AP-3 μ1, a subunit of the AP-3 adaptor complex involved in protein trafficking to lysosomal organelles. This leads to destabilization of the AP-3 complex, missorting of AP-3 cargo, and lysosomal defects. Restoring AP-3μ1 expression ameliorates neurotoxicity caused by β proteins. Altogether, our results highlight the link between protein aggregation, lysosomal impairments, and neurotoxicity.

scholarly journals Ykt6 membrane-to-cytosol cycling regulates exosomal Wnt secretion

2018 ◽  
Author(s):  
Karen Linnemannstöns ◽  
Pradhipa Karuna M ◽  
Leonie Witte ◽  
Jeanette Clarissa Kittel ◽  
Adi Danieli ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Wnt Signaling ◽  
Signaling Pathways ◽  
Long Range ◽  
Protein Trafficking ◽  
Secretory Pathway ◽  
Multivesicular Bodies ◽  
Phosphorylation Sites ◽  
Wnt Proteins ◽  
C Terminus

Protein trafficking in the secretory pathway, for example the secretion of Wnt proteins, requires tight regulation. These ligands activate Wnt signaling pathways and are crucially involved in development and disease. Wnt is transported to the plasma membrane by its cargo receptor Evi, where Wnt/Evi complexes are endocytosed and sorted onto exosomes for long-range secretion. However, the trafficking steps within the endosomal compartment are not fully understood. The promiscuous SNARE Ykt6 folds into an auto-inhibiting conformation in the cytosol, but a portion associates with membranes by its farnesylated and palmitoylated C-terminus. Here, we demonstrate that membrane detachment of Ykt6 is essential for exosomal Wnt secretion. We identified conserved phosphorylation sites within the SNARE domain of Ykt6, which block Ykt6 cycling from the membrane to the cytosol. In Drosophila, Ykt6-RNAi mediated block of Wg secretion is rescued by wildtype but not phosphomimicking Ykt6. The latter accumulates at membranes, while wildtype Ykt6 regulates Wnt trafficking between the plasma membrane and multivesicular bodies. Taken together, we show that a regulatory switch in Ykt6 fine-tunes sorting of Wnts in endosomes.

scholarly journals MIA3/TANGO1 enables efficient secretion by constraining COPII vesicle budding

2021 ◽  
Author(s):  
Janine McCaughey ◽  
Judith M. Mantell ◽  
Chris R. Neal ◽  
Kate Heesom ◽  
David J. Stephens
Keyword(s):  
Endoplasmic Reticulum ◽  
Light Microscopy ◽  
Secretory Pathway ◽  
Genome Engineering ◽  
High Volume ◽  
Vesicle Budding ◽  
Early Secretory Pathway ◽  
Copii Vesicle ◽  
Intermediate Compartment ◽  
Golgi Organization

AbstractComplex machinery is required to drive secretory cargo export from the endoplasmic reticulum. In vertebrates, this includes transport and Golgi organization protein 1 (TANGO1), encoded by the Mia3 gene. Here, using genome engineering of human cells light microscopy, secretion assays, and proteomics, we show loss of Mia3/TANGO1 results in formation of numerous vesicles and a loss of early secretory pathway integrity. This restricts secretion not only of large proteins like procollagens but of all types of secretory cargo. Our data shows that Mia3/TANGO1 constrains the propensity of COPII to form vesicles promoting instead the formation of the ER-Golgi intermediate compartment. Thus, Mia3/TANGO1 facilities the secretion of complex and high volume cargoes from vertebrate cells.

scholarly journals Single-cell transcriptional dynamics of flavivirus infection

2017 ◽  
Author(s):  
Fabio Zanini ◽  
Szu-Yuan Pu ◽  
Elena Bekerman ◽  
Shirit Einav ◽  
Stephen R. Quake
Keyword(s):  
Single Cell ◽  
Membrane Trafficking ◽  
Viral Infections ◽  
Cultured Cells ◽  
Complex Dynamics ◽  
Single Cell Level ◽  
Cell Level ◽  
Transcriptional Dynamics ◽  
High Degree ◽  
Virus Abundance

ABSTRACTDengue and Zika viral infections affect millions of people annually and can be complicated by hemorrhage or neurological manifestations, respectively. However, a thorough understanding of the host response to these viruses is lacking, partly because conventional approaches ignore heterogeneity in virus abundance across cells. We present viscRNA-Seq (virus-inclusive single cell RNA-Seq), an approach to probe the host transcriptome together with intracellular viral RNA at the single cell level. We applied viscRNA-Seq to monitor dengue and Zika virus infection in cultured cells and discovered extreme heterogeneity in virus abundance. We exploited this variation to identify host factors that show complex dynamics and a high degree of specificity for either virus, including proteins involved in the endoplasmic reticulum translocon, signal peptide processing, and membrane trafficking. We validated the viscRNA-Seq hits and discovered novel proviral and antiviral factors. viscRNA-Seq is a powerful approach to assess the genome-wide virus-host dynamics at single cell level.

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