scholarly journals Hop-on hop-off: Polysomes take a tour of the cell on endosomes

2014 ◽  
Vol 204 (3) ◽  
pp. 287-289 ◽  
Author(s):  
Isabel M. Palacios
Keyword(s):  
Protein Synthesis ◽  
Long Range ◽  
Ustilago Maydis ◽  
Hyphal Cell ◽  
Translation Machinery ◽  
Cell Biol ◽  
Early Endosomes ◽  
Entire Cell ◽  
Bidirectional Movement

After export from the nucleus, ribosomes need to be distributed throughout the entire cell so that protein synthesis can occur even at distant sites. In the elongated hyphal cell of the fungus Ustilago maydis, Higuchi et al. (2014. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201307164) now demonstrate that polysomes associate with early endosomes that undergo kinesin 3– and dynein-dependent long-range motility. The bidirectional movement of early endosomes randomly distributes polysomes, which may ensure the even distribution of the translation machinery across the entire cell.

scholarly journals Mathematical model with spatially uniform regulation explains long-range bidirectional transport of early endosomes in fungal hyphae

2014 ◽  
Vol 25 (16) ◽  
pp. 2408-2415 ◽  
Author(s):  
Jia Gou ◽  
Leah Edelstein-Keshet ◽  
Jun Allard
Keyword(s):  
Mathematical Model ◽  
Long Range ◽  
Spatial Organization ◽  
Ustilago Maydis ◽  
Transition Rates ◽  
Site Distribution ◽  
Early Endosomes ◽  
Range Transport ◽  
Bidirectional Transport ◽  
Kinesin Family

In many cellular contexts, cargo is transported bidirectionally along microtubule bundles by dynein and kinesin-family motors. Upstream factors influence how individual cargoes are locally regulated, as well as how long-range transport is regulated at the whole-cell scale. Although the details of local, single-cargo bidirectional switching have been extensively studied, it remains to be elucidated how this results in cell-scale spatial organization. Here we develop a mathematical model of early endosome transport in Ustilago maydis. We demonstrate that spatiotemporally uniform regulation, with constant transition rates, results in cargo dynamics that is consistent with experimental data, including data from motor mutants. We find that microtubule arrays can be symmetric in plus-end distribution but asymmetric in binding-site distribution in a manner that affects cargo dynamics and that cargo can travel past microtubule ends in microtubule bundles. Our model makes several testable predictions, including secondary features of dynein and cargo distributions.

scholarly journals The novel Rab5 effector FERRY links early endosomes with the translation machinery

2021 ◽  
Author(s):  
Jan S Schuhmacher ◽  
Susanne tom Dieck ◽  
Savvas Christoforidis ◽  
Cedric Landerer ◽  
Lena Hersemann ◽  
...  
Keyword(s):  
Mental Retardation ◽  
Mrna Localization ◽  
Mitochondrial Proteins ◽  
The Novel ◽  
Translation Machinery ◽  
Early Endosomes ◽  
Close Proximity ◽  
Polarized Cells ◽  
Entire Cell ◽  
Underlying Mechanisms

Local translation is vital to polarized cells such as neurons and requires a precise and robust distribution of different mRNAs and the translation machinery across the entire cell. The underlying mechanisms are poorly understood and important players are still to be identified. Here, we discovered a novel Rab5 effector complex which leads to mental retardation when genetically disrupted. The Five-subunit Endosomal Rab5 and RNA/ribosome intermediarY, FERRY complex localizes to early endosomes and associates with the translation machinery and a subset of mRNAs including mRNAs for mitochondrial proteins. It directly interacts with mRNA, thereby exhibiting different binding efficacies. Deletion of FERRY subunits reduces the endosomal localization of transcripts, indicating a role in mRNA distribution. Accordingly, FERRY-positive early endosomes harboring mRNA encoding mitochondrial proteins were observed in close proximity to mitochondria in neurons. Therefore, the FERRY complex plays a role for mRNA localization by linking early endosomes with the translation machinery.

scholarly journals Kinesin-3 and dynein cooperate in long-range retrograde endosome motility along a nonuniform microtubule array

2011 ◽  
Vol 22 (19) ◽  
pp. 3645-3657 ◽  
Author(s):  
Martin Schuster ◽  
Sreedhar Kilaru ◽  
Gero Fink ◽  
Jérôme Collemare ◽  
Yvonne Roger ◽  
...  
Keyword(s):  
Long Range ◽  
Temperature Sensitive ◽  
Middle Region ◽  
Growing Cell ◽  
Early Endosomes ◽  
Complex Protein ◽  
Ring Complex ◽  
Entire Cell ◽  
Run Up ◽  
Intracellular Motility

The polarity of microtubules (MTs) determines the motors for intracellular motility, with kinesins moving to plus ends and dynein to minus ends. In elongated cells of Ustilago maydis, dynein is thought to move early endosomes (EEs) toward the septum (retrograde), whereas kinesin-3 transports them to the growing cell tip (anterograde). Occasionally, EEs run up to 90 μm in one direction. The underlying MT array consists of unipolar MTs at both cell ends and antipolar bundles in the middle region of the cell. Cytoplasmic MT-organizing centers, labeled with a γ-tubulin ring complex protein, are distributed along the antipolar MTs but are absent from the unipolar regions. Dynein colocalizes with EEs for 10–20 μm after they have left the cell tip. Inactivation of temperature-sensitive dynein abolishes EE motility within the unipolar MT array, whereas long-range motility is not impaired. In contrast, kinesin-3 is continuously present, and its inactivation stops long-range EE motility. This indicates that both motors participate in EE motility, with dynein transporting the organelles through the unipolar MT array near the cell ends, and kinesin-3 taking over at the beginning of the medial antipolar MT array. The cooperation of both motors mediates EE movements over the length of the entire cell.

scholarly journals The preendosomal compartment comprises distinct coated and noncoated endocytic vesicle populations.

1991 ◽  
Vol 113 (4) ◽  
pp. 731-741 ◽  
Author(s):  
S H Hansen ◽  
K Sandvig ◽  
B van Deurs
Keyword(s):  
Cell Surface ◽  
Coated Vesicles ◽  
Minor Role ◽  
Specific Marker ◽  
Con A ◽  
Early Endosomes ◽  
Gold Conjugate ◽  
Entire Cell ◽  
A Minor ◽  
Endocytic Vesicles

The transfer of molecules from the cell surface to the early endosomes is mediated by preendosomal vesicles. These vesicles, which have pinched off completely from the plasma membrane but not yet fused with endosomes, form the earliest compartment along the endocytic route. Using a new assay to distinguish between free and cell surface connected vesicle profiles, we have characterized the preedosomal compartment ultrastructurally. Our basic experimental setup was labeling of the entire cell surface at 4 degrees C with Con A-gold, warming of the cells to 37 degrees C to allow endocytosis, followed by replacing incubation medium with fixative, all within either 30 or 60 s. Then the fixed cells were incubated with anti-Con A-HRP to distinguish truly free (gold labeled) endocytic vesicles from surface-connected structures. Finally, analysis of thin (20-30 nm) serial sections and quantification of vesicle diameters were carried out. Based on this approach it is shown that the preendosomal compartment comprises both clathrin-coated and non-coated endocytic vesicles with approximately the same frequency but with distinct diameter distributions, the average noncoated vesicle being smaller (95 nm) than the average coated one (110 nm). In parallel experiments, using an anti-transferrin receptor gold-conjugate as a specific marker for clathrin-dependent endocytosis it is also shown that uncoating of coated vesicles plays only a minor role for the total frequency of noncoated vesicles. Furthermore, after perturbation of clathrin-dependent endocytosis by potassium depletion where uptake of transferrin is blocked, noncoated endocytic vesicles with Con A-gold, but not coated vesicles, exist already after 30 and 60 s. Finally, it is shown that the existence of small, free vesicles in the short-time experiments cannot be ascribed to recycling from the early endosomes.

Endocytic mechanisms responsible for uptake of GPI-linked diphtheria toxin receptor

1999 ◽  
Vol 112 (22) ◽  
pp. 3899-3909 ◽  
Author(s):  
G. Skretting ◽  
M.L. Torgersen ◽  
B. van Deurs ◽  
K. Sandvig
Keyword(s):  
Protein Synthesis ◽  
Cell Surface ◽  
Hela Cells ◽  
Diphtheria Toxin ◽  
Surface Receptors ◽  
Caveolin 1 ◽  
Ultrastructural Studies ◽  
Diphtheria Toxin Receptor ◽  
Early Endosomes ◽  
Toxin Receptor

We have here used diphtheria toxin as a tool to investigate the type of endocytosis used by a glycosylphosphatidylinositol-linked molecule, a glycosylphosphatidylinositol-linked version of the diphtheria toxin receptor that is able to mediate intoxication. The receptor is expressed in HeLa cells where clathrin-dependent endocytosis can be blocked by overexpression of mutant dynamin. Diphtheria toxin intoxicates cells by first binding to cell-surface receptors, then the toxin is endocytosed, and upon exposure to low endosomal pH, the toxin enters the cytosol where it inhibits protein synthesis. Inhibition of protein synthesis by the toxin can therefore be used to probe the entry of the glycosylphosphatidylinositol-linked receptor into an acidic compartment. Furthermore, degradation of the toxin can be used as an indicator of entry into the endosomal/lysosomal compartment. The data show that although expression of mutant dynamin inhibits intoxication mediated via the wild-type receptors, mutant dynamin does not affect intoxication or endocytosis and degradation of diphtheria toxin bound to the glycosylphosphatidylinositol-linked receptor. Confocal microscopy demonstrated that diphtheria toxin is transported to vesicles containing EEA1, a marker for early endosomes. Biochemical and ultrastructural studies of the HeLa cells used reveal that they have very low levels of caveolin-1 and that they contain very few if any caveolae at the cell surface. Furthermore, the endocytic uptake of diphtheria toxin bound to the glycosylphosphatidylinositol-linked receptor was not reduced by methyl-beta-cyclodextrin or by nystatin which both disrupt caveolar structure and functions. Thus, uptake of a glycosylphosphatidylinositol-linked protein, in this case the diphtheria toxin receptor, into the endosomal/lysosomal system can occur independently of both caveolae and clathrin-coated vesicles.

scholarly journals Keratins and protein synthesis: the plot thickens

2009 ◽  
Vol 187 (2) ◽  
pp. 157-159 ◽  
Author(s):  
Juliane C. Kellner ◽  
Pierre A. Coulombe
Keyword(s):  
Protein Synthesis ◽  
Cell Growth ◽  
Epithelial Cells ◽  
Mechanical Stress ◽  
Gene Cluster ◽  
Organelle Transport ◽  
Type Ii ◽  
Keratin Gene ◽  
Cell Biol ◽  
Keratin Proteins

In addition to protecting epithelial cells from mechanical stress, keratins regulate cytoarchitecture, cell growth, proliferation, apoptosis, and organelle transport. In this issue, Vijayaraj et al. (2009. J. Cell Biol. doi:10.1083/jcb.200906094) expand our understanding of how keratin proteins participate in the regulation of protein synthesis through their analysis of mice lacking the entire type II keratin gene cluster.

scholarly journals The Chlamydomonas kinesin-like protein FLA10 is involved in motility associated with the flagellar membrane.

1995 ◽  
Vol 131 (6) ◽  
pp. 1517-1527 ◽  
Author(s):  
K G Kozminski ◽  
P L Beech ◽  
J L Rosenbaum
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Intraflagellar Transport ◽  
Temperature Sensitive ◽  
Polystyrene Beads ◽  
Cell Biol ◽  
Flagellar Membrane ◽  
Surface Motility ◽  
Sensitive Allele ◽  
Bidirectional Movement

The Chlamydomonas FLA10 gene was shown to encode a flagellar kinesin-like protein (Walther, Z., M. Vashishtha, and J.L. Hall. 1994. J. Cell Biol. 126:175-188). By using a temperature-sensitive allele of FLA10, we have determined that the FLA10 protein is necessary for both the bidirectional movement of polystyrene beads on the flagellar membrane and intraflagellar transport (IFT), the bidirectional movement of granule-like particles beneath the flagellar membrane (Kozminski, K.G., K.A. Johnson, P. Forscher, and J.L. Rosenbaum. 1993. Proc. Natl. Acad. Sci. (USA). 90:5519-5523). In addition, we have correlated the presence and position of the IFT particles visualized by light microscopy with that of the electron dense complexes (rafts) observed beneath the flagellar membrane by electron microscopy. A role for FLA10 in submembranous or flagellar surface motility is also strongly supported by the immunolocalization of FLA10 to the region between the axonemal outer doublet microtubules and the flagellar membrane.

scholarly journals LIGAND-INDUCED MOVEMENT OF LYMPHOCYTE MEMBRANE MACROMOLECULES

1973 ◽  
Vol 137 (3) ◽  
pp. 675-689 ◽  
Author(s):  
Emil R. Unanue ◽  
Morris J. Karnovsky ◽  
Howard D. Engers
Keyword(s):  
Protein Synthesis ◽  
Cell Membrane ◽  
Cell Surface ◽  
Oxidative Phosphorylation ◽  
Cross Linking ◽  
Lymphocyte Membrane ◽  
Compact Zone ◽  
Entire Cell ◽  
Freeze Etching ◽  
Spleen Lymphocytes

Spleen lymphocytes were studied for the movement and interiorization of complexes of anti-Ig-surface Ig. The movement of the complex into a small, compact zone of the cell membrane (forming a cap) was inhibited by drugs that inhibited glycolysis and oxidative phosphorylation, but not by drugs that affected protein synthesis. Dead lymphocytes did not form caps. Freeze-etching techniques revealed that inhibited lymphocytes showed formation of multiple small complexes over the entire cell surface. Inhibitors of glycolysis and of oxidative phosphorylation also inhibited the interiorization and catabolism of radioiodinated anti-Ig. We hypothesize that cross-linking of all the surface Ig triggers the membrane movements that are required to pull the lattice into one zone of the cell.

scholarly journals Lysine Demethylase KDM4A Associates with Translation Machinery and Regulates Protein Synthesis

2015 ◽  
Vol 5 (3) ◽  
pp. 255-263 ◽  
Author(s):  
Capucine Van Rechem ◽  
Joshua C. Black ◽  
Myriam Boukhali ◽  
Martin J. Aryee ◽  
Susanne Gräslund ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Translation Machinery ◽  
Lysine Demethylase

scholarly journals Structure-Activity Relationship Studies of Retro-1 Analogues Against Shiga Toxin

2020 ◽  
Author(s):  
Hajer Abdelkafi ◽  
Aurélien Michau ◽  
Valérie Pons ◽  
Flora Ngadjeua ◽  
Alexandra Clerget ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Shiga Toxin ◽  
Intracellular Trafficking ◽  
High Throughput Screening ◽  
Cell Protein ◽  
Shiga Toxins ◽  
Structure Activity ◽  
Early Endosomes ◽  
A Cell ◽  
Sar Study

<p>The Retro-1 molecule was identified in a high-throughput screening as an inhibitor of ricin and Shiga toxins by diminishing their intracellular trafficking <i>via</i> the retrograde route, from early endosomes to the Golgi apparatus. In order to improve the activity of Retro-1, a SAR study was undertaken yielding an analog that possesses roughly 70-fold better EC<sub>50</sub> against Shiga toxin cytotoxicity measured in a cell protein synthesis assay. </p>

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