scholarly journals Genetic dissection of early endosomal recycling highlights a TORC1-independent role for Rag GTPases

2017 ◽  
Vol 216 (10) ◽  
pp. 3275-3290 ◽  
Author(s):  
Chris MacDonald ◽  
Robert C. Piper
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Surface Membrane ◽  
Physiological Role ◽  
Amino Acid Transporters ◽  
Genetic Dissection ◽  
Cellular Processes ◽  
Rag Gtpases ◽  
Endosomal Recycling ◽  
Recycling Pathway

Endocytosed cell surface membrane proteins rely on recycling pathways for their return to the plasma membrane. Although endosome-to-plasma membrane recycling is critical for many cellular processes, much of the required machinery is unknown. We discovered that yeast has a recycling route from endosomes to the cell surface that functions efficiently after inactivation of the sec7-1 allele of Sec7, which controls transit through the Golgi. A genetic screen based on an engineered synthetic reporter that exclusively follows this pathway revealed that recycling was subject to metabolic control through the Rag GTPases Gtr1 and Gtr2, which work downstream of the exchange factor Vam6. Gtr1 and Gtr2 control the recycling pathway independently of TORC1 regulation through the Gtr1 interactor Ltv1. We further show that the early-endosome recycling route and its control though the Vam6>Gtr1/Gtr2>Ltv1 pathway plays a physiological role in regulating the abundance of amino acid transporters at the cell surface.

scholarly journals Surface redistribution and release of antibody-induced caps in entamoebae.

1980 ◽  
Vol 151 (1) ◽  
pp. 184-193 ◽  
Author(s):  
J Calderón ◽  
M de Lourdes Muñoz ◽  
H M Acosta
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Surface Segregation ◽  
Surface Membrane ◽  
Single Layer ◽  
Surface Antigens ◽  
Spontaneous Release ◽  
Plasma Membrane Regeneration ◽  
Membrane Components ◽  
Radiolabeled Antibodies

Polyspecific antibodies bound to Entamoeba induced surface redistribution of membrane components toward the uroid region. Capping of surface antigens was obtained with a single layer of antibodies in E. histolytica and E. invadens. This surface segregation progressed to a large accumulation of folded plasma membrane that extruded as a defined vesicular cap. A spontaneous release of the cap at the end of the capping process took place. These released caps contained most of the antibodies that originally bound to the whole cell surface. Two-thirds of radiolabeled antibodies bound to the surface of E. histolytica were released into the medium in 2 h. Successive capping induced by repeated exposure of E. invadens to antibodies produced conglomerates of folded surface membrane, visualized as stacked caps, in proportion to the number of antibody exposures. These results indicate the remarkable ability of Entamoeba to rapidly regenerate substantial amounts of plasma membbrane. The properties of surface redistribution, liberation of caps, and plasma membrane regeneration, may contribute to the survival of the parasite in the host during infection.

In Vivo Internalization of the Somatostatin sst2A Receptor in Rat Brain: Evidence for Translocation of Cell-Surface Receptors into the Endosomal Recycling Pathway

2001 ◽  
Vol 17 (4) ◽  
pp. 646-661 ◽  
Author(s):  
Zsolt Csaba ◽  
Véronique Bernard ◽  
Lone Helboe ◽  
Marie-Thérèse Bluet-Pajot ◽  
Bertrand Bloch ◽  
...  
Keyword(s):  
Cell Surface ◽  
Rat Brain ◽  
Cell Surface Receptors ◽  
Surface Receptors ◽  
Endosomal Recycling ◽  
Recycling Pathway

scholarly journals Integrin-dependent YAP signaling requires LAMTOR1 mediated delivery of Src to the plasma membrane

2019 ◽  
Author(s):  
Marc R. Block ◽  
Molly Brunner ◽  
Théo Ziegelmeyer ◽  
Dominique Lallemand ◽  
Mylène Pezet ◽  
...  
Keyword(s):  
Cell Periphery ◽  
Matrix Stiffness ◽  
Cell Contractility ◽  
Cellular Processes ◽  
Endosomal Recycling ◽  
Late Endosomes ◽  
Extracellular Matrix Stiffness ◽  
Important Regulator ◽  
Recycling Pathway ◽  
Nuclear Shuttling

AbstractYAP signaling has emerged as an important signaling pathway involved in several normal and pathological processes. While main upstream effectors regulating its activity have been extensively studied, the interplay with other cellular processes has been far less analyzed. Here, we identified the LAMTOR complex as a new important regulator of YAP signaling. We uncovered that p18/LAMTOR1 is required for the recycling of Src on late endosomes to the cell periphery, and consequently to activate a signaling cascade that eventually controls YAP nuclear shuttling. Moreover, p18/LAMTOR1 positives late endosomes distribution is controlled by β1 integrins, extracellular matrix stiffness and cell contractility. This likely relies on the targeting of microtubules to β1 positive focal adhesion via ILK. Altogether our findings identify the late endosomal recycling pathway as a major regulator of YAP.

Repairing a torn cell surface: make way, lysosomes to the rescue

2002 ◽  
Vol 115 (5) ◽  
pp. 873-879 ◽  
Author(s):  
Paul L. McNeil
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Actin Polymerization ◽  
Surface Membrane ◽  
Cell Cortex ◽  
Yolk Granule ◽  
Protein Markers ◽  
Filamentous Actin ◽  
Animal Cells ◽  
Fusion Plasma

Biological membranes are often described as `self-sealing' structures. If indeed membranes do have an inherent capacity for repair, does this explain how a cell can rapidly reseal a very large (1-1000 μm2)disruption in its plasma membrane? It is becoming increasingly clear that, in nucleated animal cells, the cytoplasm plays an active and essential role in resealing. A rapid and apparently chaotic membrane fusion response is initiated locally in the cytoplasm by the Ca2+ that floods in through a disruption: cytoplasmic vesicles are thereby joined with one another(homotypically) and with the surrounding plasma membrane (exocytotically). As a consequence, internal membrane is added to cell surface membrane at the disruption site. In the case of large disruptions, this addition is hypothesized to function as a `patch'. In sea urchin eggs, the internal compartment used is the yolk granule. Several recent studies have significantly advanced our understanding of how cells survive disruption-inducing injuries. In fibroblasts, the lysosome has been identified as a key organelle in resealing. Protein markers of the lysosome membrane appear on the surface of fibroblasts at sites of disruption. Antibodies against lysosome-specific proteins, introduced into the living fibroblast,inhibit its resealing response. In gastric eptithelial cells, local depolymerization of filamentous actin has been identified as a crucial step in resealing: it may function to remove a barrier to lysosome-plasma membrane contact leading to exocytotic fusion. Plasma membrane disruption in epithelial cells induces depolymerization of cortical filamentous actin and, if this depolymerization response is inhibited, resealing is blocked. In the Xenopus egg, the cortical cytoskeleton has been identified as an active participant in post-resealing repair of disruption-related damage to underlying cell cortex. A striking, highly localized actin polymerization response is observable around the margin of cortical defects. A myosin powered contraction occurring within this newly formed zone of F-actin then drives closure of the defect in a purse-string fashion.

scholarly journals GLUT4 Retention in Adipocytes Requires Two Intracellular Insulin-regulated Transport Steps

2002 ◽  
Vol 13 (7) ◽  
pp. 2421-2435 ◽  
Author(s):  
Anja Zeigerer ◽  
Michael A. Lampson ◽  
Ola Karylowski ◽  
David D. Sabatini ◽  
Milton Adesnik ◽  
...  
Keyword(s):  
Cell Surface ◽  
Transferrin Receptor ◽  
Glucose Transporter ◽  
Trafficking Pathway ◽  
Endosomal Recycling ◽  
Step Model ◽  
Recycling Pathway ◽  
Endosomal Pathway ◽  
Endosomal System ◽  
Regulated Trafficking

Insulin regulates glucose uptake into fat and muscle by modulating the distribution of the GLUT4 glucose transporter between the surface and interior of cells. The GLUT4 trafficking pathway overlaps with the general endocytic recycling pathway, but the degree and functional significance of the overlap are not known. In this study of intact adipocytes, we demonstrate, by using a compartment-specific fluorescence-quenching assay, that GLUT4 is equally distributed between two intracellular pools: the transferrin receptor-containing endosomes and a specialized compartment that excludes the transferrin receptor. These pools of GLUT4 are in dynamic communication with one another and with the cell surface. Insulin-induced redistribution of GLUT4 to the surface requires mobilization of both pools. These data establish a role for the general endosomal system in the specialized, insulin-regulated trafficking of GLUT4. Trafficking through the general endosomal system is regulated by rab11. Herein, we show that rab11 is required for the transport of GLUT4 from endosomes to the specialized compartment and for the insulin-induced translocation to the cell surface, emphasizing the importance of the general endosomal pathway in the specialized trafficking of GLUT4. Based on these findings we propose a two-step model for GLUT4 trafficking in which the general endosomal recycling compartment plays a specialized role in the insulin-regulated traffic of GLUT4. This compartment-based model provides the framework for understanding insulin-regulated trafficking at a molecular level.

scholarly journals Ganglioside Synthesis by Plasma Membrane-Associated Sialyltransferase in Macrophages

2020 ◽  
Vol 21 (3) ◽  
pp. 1063
Author(s):  
Aldo Vilcaes ◽  
Eduardo Garbarino-Pico ◽  
Vanina Torres Demichelis ◽  
Jose Daniotti
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Fluorescent Microscopy ◽  
Physiological Role ◽  
No Synthase ◽  
Raw264.7 Cells ◽  
No Production ◽  
Ganglioside Metabolism ◽  
Gd3 Ganglioside

Gangliosides are constituents of the mammalian cell membranes and participate in the inflammatory response. However, little is known about the presence and enzymatic activity of ganglioside sialyltransferases at the cell surface of macrophages, one of the most important immune cells involved in the innate inflammatory process. In the present study, using biochemical and fluorescent microscopy approaches, we found that endogenous ST8Sia-I is present at the plasma membrane (ecto-ST8Sia-I) of murine macrophage RAW264.7 cells. Moreover, ecto-ST8Sia-I can synthetize GD3 ganglioside at the cell surface in lipopolysaccharide (LPS)-stimulated macrophages even when LPS-stimulated macrophages reduced the total ST8Sia-I expression levels. Besides, cotreatment of LPS with an inhibitor of nitric oxide (NO) synthase recovered the ecto-ST8Sia-I expression, suggesting that NO production is involved in the reduction of ST8Sia-I expression. The diminution of ST8Sia-I expression in LPS-stimulated macrophages correlated with a reduction of GD3 and GM1 gangliosides and with an increment of GD1a. Taken together, the data supports the presence and activity of sialyltransferases at the plasma membrane of RAW264.7 cells. The variations of ecto-ST8Sia-I and ganglioside levels in stimulated macrophages constitutes a promissory pathway to further explore the physiological role of this and others ganglioside metabolism-related enzymes at the cell surface during the immune response.

scholarly journals Malaria circumsporozoite protein binds to heparan sulfate proteoglycans associated with the surface membrane of hepatocytes.

1993 ◽  
Vol 177 (5) ◽  
pp. 1287-1298 ◽  
Author(s):  
U Frevert ◽  
P Sinnis ◽  
C Cerami ◽  
W Shreffler ◽  
B Takacs ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Heparan Sulfate ◽  
Target Cell ◽  
Surface Membrane ◽  
Heparan Sulfate Proteoglycans ◽  
Circumsporozoite Protein ◽  
Cell Specificity ◽  
Region Ii

During feeding by infected mosquitoes, malaria sporozoites are injected into the host's bloodstream and enter hepatocytes within minutes. The remarkable target cell specificity of this parasite may be explained by the presence of receptors for the region II-plus of the circumsporozoite protein (CS) on the basolateral domain of the plasma membrane of hepatocytes. We have now identified these receptors as heparan sulfate proteoglycans (HSPG). The binding of CS to the receptors is abolished by heparitinase treatment, indicating that the recognition of region II-plus is via the glycosaminoglycan chains. We have purified and partially characterized the CS-binding HSPGs from HepG2 cells. They have a molecular weight of 400,000-700,000, are tightly associated with the plasma membrane, and are released from the cell surface by very mild trypsinization, a property which the CS receptors share with the syndecan family of proteoglycans.

scholarly journals Saponin-induced release of cell-surface-anchored Thy-1 by serum glycosylphosphatidylinositol-specific phospholipase D

1994 ◽  
Vol 298 (3) ◽  
pp. 661-668 ◽  
Author(s):  
A S Bergman ◽  
S R Carlsson
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Human Serum ◽  
Lipid Bilayer ◽  
Phospholipase D ◽  
Physiological Role ◽  
Highly Active ◽  
T Lymphoma Cells ◽  
T Lymphoma

A glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) was purified from human serum and used for studies on the release of GPI-anchored Thy-1 glycoprotein from mouse T lymphoma cells Y191. Previous studies have shown that whereas GPI-PLD is highly active against detergent-solubilized GPI-anchored proteins, it is normally unable to release GPI-containing proteins anchored in a lipid bilayer. Confirming these findings, the addition of GPI-PLD to intact Y191 cells did not result in cleavage of Thy-1. However, pretreatment of cells with saponin, a cholesterol-sequestering agent, rendered Thy-1 susceptible to hydrolysis. Very little solubilization of GPI-containing Thy-1 occurred under these conditions. From experiments with reconstituted liposomes it was inferred that the effect of saponin on cells was to aid in the presentation of Thy-1 to GPI-PLD. Furthermore, it was concluded that cholesterol-saponin complexes formed in the membrane were not alone responsible for the effect. Rather, additional molecules in the plasma membrane are possibly involved in the presentation of Thy-1 on saponin-treated cells. This finding may have implications for a physiological role of circulating GPI-PLD in the regulation of GPI-anchored proteins on cells.

scholarly journals Identification of detergent-resistant plasma membrane microdomains in dictyostelium: enrichment of signal transduction proteins.

1997 ◽  
Vol 8 (5) ◽  
pp. 855-869 ◽  
Author(s):  
Z Xiao ◽  
P N Devreotes
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Cell Surface ◽  
G Protein ◽  
Biochemical Characterization ◽  
Surface Membrane ◽  
Actin Binding ◽  
Membrane Microdomains ◽  
Immunogold Electron Microscopy ◽  
Membrane Structures

Unlike most other cellular proteins, the chemoattractant receptor, cAR1, of Dictyostelium is resistant to extraction by the zwitterionic detergent, CHAPS. We exploited this property to isolate a subcellular fraction highly enriched in cAR1 by flotation of CHAPS lysates of cells in sucrose density gradients. Immunogold electron microscopy studies revealed a homogeneous preparation of membrane bilayer sheets. This preparation, designated CHAPS-insoluble floating fraction (CHIEF), also contained a defined set of 20 other proteins and a single uncharged lipid. Cell surface biotinylation and preembedding immunoelectron microscopy both confirmed the plasma membrane origin of this preparation. The cell surface phosphodiesterase (PDE) and a downstream effector of cAR1, adenylate cyclase (ACA), were specifically localized in these structures, whereas the cell adhesion molecule gp80, most of the major cell surface membrane proteins, cytoskeletal components, the actin-binding integral membrane protein ponticulin, and G-protein alpha- and beta-subunits were absent. Overall, CHIFF represents about 3-5% of cell externally exposed membrane proteins. All of these results indicate that CHIFF is derived from specialized microdomains of the plasma membrane. The method of isolation is analogous to that of caveolae. However, we were unable to detect distinct caveolae-like structures on the cell surface associated with cAR1, which showed a diffuse staining profile. The discovery of CHIFF facilitates the purification of cAR1 and related signaling proteins and the biochemical characterization of receptor-mediated processes such as G-protein activation and desensitization. It also has important implications for the "fluid mosaic" model of the plasma membrane structures.

scholarly journals Rab8 Regulates Basolateral Secretory, But Not Recycling, Traffic at the Recycling Endosome

2008 ◽  
Vol 19 (5) ◽  
pp. 2059-2068 ◽  
Author(s):  
Lauren Henry ◽  
David R. Sheff
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Mdck Cells ◽  
Apical Surface ◽  
Recycling Endosome ◽  
Recycling Pathway ◽  
Polarized Epithelial Cells ◽  
Pass Through

Rab8 is a monomeric GTPase that regulates the delivery of newly synthesized proteins to the basolateral surface in polarized epithelial cells. Recent publications have demonstrated that basolateral proteins interacting with the μ1-B clathrin adapter subunit pass through the recycling endosome (RE) en route from the TGN to the plasma membrane. Because Rab8 interacts with these basolateral proteins, these findings raise the question of whether Rab8 acts before, at, or after the RE. We find that Rab8 overexpression during the formation of polarity in MDCK cells, disrupts polarization of the cell, explaining how Rab8 mutants can disrupt basolateral endocytic and secretory traffic. However, once cells are polarized, Rab8 mutants cause mis-sorting of newly synthesized basolateral proteins such as VSV-G to the apical surface, but do not cause mis-sorting of membrane proteins already at the cell surface or in the endocytic recycling pathway. Enzymatic ablation of the RE also prevents traffic from the TGN from reaching the RE and similarly results in mis-sorting of newly synthesized VSV-G. We conclude that Rab8 regulates biosynthetic traffic through REs to the plasma membrane, but not trafficking of endocytic cargo through the RE. The data are consistent with a model in which Rab8 functions in regulating the delivery of TGN-derived cargo to REs.

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