Gallium-Inducible Transferrin-Independent Iron Acquisition Is a Property of Many Cell Types: Possible Role of Alterations in the Plasma Membrane

2005 ◽  
Vol 53 (3) ◽  
pp. 143-153 ◽  
Author(s):  
Oyebode Olakanmi ◽  
John B. Stokes ◽  
Bradley E. Britigan
Keyword(s):  
Plasma Membrane ◽  
Iron Acquisition ◽  
Cell Types

Effects of bafilomycin A1 on cytosolic pH of sheep alveolar and peritoneal macrophages: evaluation of the pH-regulatory role of plasma membrane V-ATPases.

1995 ◽  
Vol 198 (8) ◽  
pp. 1711-1715 ◽  
Author(s):  
T A Heming ◽  
D L Traber ◽  
F Hinder ◽  
A Bidani
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Initial Rate ◽  
Cell Types ◽  
Peritoneal Macrophages ◽  
Bafilomycin A1 ◽  
Atpase Inhibitor ◽  
Cytosolic Ph ◽  
Phi Regulation

The role of plasma membrane V-ATPase activity in the regulation of cytosolic pH (pHi) was determined for resident alveolar and peritoneal macrophages (m theta) from sheep. Cytosolic pH was measured using 2',7'-biscarboxyethyl-5,6-carboxyfluorescein (BCECF). The baseline pHi of both cell types was sensitive to the specific V-ATPase inhibitor bafilomycin A1. Bafilomycin A1 caused a significant (approximately 0.2 pH units) and rapid (within seconds) decline in baseline pHi. Further, bafilomycin A1 slowed the initial rate of pHi recovery (dpHi/dt) from intracellular acid loads. Amiloride had no effects on baseline pHi, but reduced dpHi/dt (acid-loaded pHi nadir < 6.8) by approximately 35%. Recovery of pHi was abolished by co-treatment of m theta with bafilomycin A1 and amiloride. These data indicate that plasma membrane V-ATPase activity is a major determinant of pHi regulation in resident alveolar and peritoneal m theta from sheep. Sheep m theta also appear to possess a Na+/H+ exchanger. However, Na+/H+ exchange either is inactive or can be effectively masked by V-ATPase-mediated H+ extrusion at physiological pHi values.

scholarly journals Lysosomal Fusion Is Essential for the Retention of Trypanosoma cruzi Inside Host Cells

2004 ◽  
Vol 200 (9) ◽  
pp. 1135-1143 ◽  
Author(s):  
Luciana O. Andrade ◽  
Norma W. Andrews
Keyword(s):  
Plasma Membrane ◽  
Life Cycle ◽  
Trypanosoma Cruzi ◽  
Parasitophorous Vacuole ◽  
Cell Types ◽  
Significant Fraction ◽  
Host Cells ◽  
Productive Infection ◽  
Kinase Inhibition

Trypomastigotes, the highly motile infective forms of Trypanosoma cruzi, are capable of infecting several cell types. Invasion occurs either by direct recruitment and fusion of lysosomes at the plasma membrane, or through invagination of the plasma membrane followed by intracellular fusion with lysosomes. The lysosome-like parasitophorous vacuole is subsequently disrupted, releasing the parasites for replication in the cytosol. The role of this early residence within lysosomes in the intracellular cycle of T. cruzi has remained unclear. For several other cytosolic pathogens, survival inside host cells depends on an early escape from phagosomes before lysosomal fusion. Here, we show that when lysosome-mediated T. cruzi invasion is blocked through phosophoinositide 3-kinase inhibition, a significant fraction of the internalized parasites are not subsequently retained inside host cells for a productive infection. A direct correlation was observed between the lysosomal fusion rates after invasion and the intracellular retention of trypomastigotes. Thus, formation of a parasitophorous vacuole with lysosomal properties is essential for preventing these highly motile parasites from exiting host cells and for allowing completion of the intracellular life cycle.

Transferrin receptor 2 mediates a biphasic pattern of transferrin uptake associated with ligand delivery to multivesicular bodies

2004 ◽  
Vol 287 (6) ◽  
pp. C1769-C1775 ◽  
Author(s):  
Aeisha D. Robb ◽  
Maria Ericsson ◽  
Marianne Wessling-Resnick
Keyword(s):  
Plasma Membrane ◽  
Transferrin Receptor ◽  
Physiological Role ◽  
Cell Types ◽  
Multivesicular Bodies ◽  
Unique Role ◽  
Biphasic Pattern ◽  
Exogenous Expression ◽  
Transferrin Uptake

The physiological role of transferrin (Tf) receptor 2 (TfR2), a homolog of the well-characterized TfR1, is unclear. Mutations in TfR2 result in hemochromatosis, indicating that this receptor has a unique role in iron metabolism. We report that HepG2 cells, which endogenously express TfR2, display a biphasic pattern of Tf uptake when presented with ligand concentrations up to 2 μM. The apparently nonsaturating pathway of Tf endocytosis resembles TfR1-independent Tf uptake, a process previously characterized in some liver cell types. Exogenous expression of TfR2 but not TfR1 induces a similar biphasic pattern of Tf uptake in HeLa cells, supporting a role for TfR2 in this process. Immunoelectron microscopy reveals that while Tf, TfR1, and TfR2 are localized in the plasma membrane and tubulovesicular endosomes, TfR2 expression is associated with the additional appearance of Tf in multivesicular bodies. These combined results imply that unlike TfR1, which recycles apo-Tf back to the cell surface after the release of iron, TfR2 promotes the intracellular deposition of ligand. Tf delivered by TfR2 does not appear to be degraded, which suggests that its delivery to this organelle may be functionally relevant to the storage of iron in overloaded states.

scholarly journals The ciliary membrane of polarized epithelial cells stems from a midbody remnant-associated membrane patch with condensed nanodomains

2019 ◽  
Author(s):  
Miguel Bernabé-Rubio ◽  
Minerva Bosch-Fortea ◽  
Esther García ◽  
Jorge Bernardino de la Serna ◽  
Miguel A. Alonso
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Primary Cilium ◽  
Mdck Cells ◽  
Cell Types ◽  
Apical Surface ◽  
Cellular Behavior ◽  
Ciliary Membrane ◽  
Lipid Dynamics

AbstractThe primary cilium is a specialized plasma membrane protrusion that harbors receptors involved in important signaling pathways. Despite its central role in regulating cellular behavior, the biogenesis of the primary cilium is not fully understood. In fact, the source of the ciliary membrane remains a mystery in cell types that assemble their primary cilium entirely at the cell surface, such as polarized renal epithelial cells. After cytokinesis, the remnant of the midbody of these cells moves to the center of the apical surface, where it licenses the centrosome for ciliogenesis through an unidentified mechanism. Here, to investigate the origin of the ciliary membrane and the role of the midbody remnant, we analyzed membrane compaction and lipid dynamics at the microscale and nanoscale in living renal epithelial MDCK cells. We found that a specialized patch made of condensed membranes with restricted lipid lateral mobility surrounds the midbody remnant. This patch accompanies the remnant on its journey towards the centrosome and, once the two structures have met, the remnant delivers part of membranes of the patch to build the ciliary membrane. In this way, we have determined the origin of the ciliary membrane and the contribution of the midbody remnant to primary cilium formation in cells whose primary cilium is assembled at the plasma membrane.

scholarly journals Intracellular Colocalization of Influenza Viral RNA and Rab11A Is Dependent upon Microtubule Filaments

2017 ◽  
Vol 91 (19) ◽  
Author(s):  
Eric Nturibi ◽  
Amar R. Bhagwat ◽  
Stefanie Coburn ◽  
Mike M. Myerburg ◽  
Seema S. Lakdawala
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Cell Types ◽  
Airway Epithelial Cells ◽  
Cytoskeletal Proteins ◽  
Viral Rna ◽  
Airway Epithelial ◽  
Public Health Burden ◽  
Cytoplasmic Transport

ABSTRACT Influenza A virus (IAV) consists of eight viral RNA (vRNA) segments that are replicated in the host cell nucleus and transported to the plasma membrane for packaging into progeny virions. We have previously proposed a model where subcomplexes of vRNA are exported from the nucleus and assembled en route to the plasma membrane. However, the role of host cytoskeletal proteins in the cytoplasmic assembly of IAV vRNA segments remains unknown. Previous studies have suggested that IAV vRNA segments are transported via Rab11A-containing recycling endosomes (RE) and use both microtubules (MT) and actin. Rab11A RE transport primarily along MT; therefore, investigation of the role of MT in vRNA assembly is warranted. We explored the role of MT in vRNA assembly and replication by using multiple IAV strains in various cell types, including primary human airway epithelial cells. We observed that Rab11A localization was altered in the presence of MT-depolymerizing drugs, but growth of IAV in all of the cell types tested was unchanged. Fluorescent in situ hybridization was performed to determine the role of MT in the assembly of multiple vRNA segments. Unexpectedly, we found that vRNA-vRNA association in cytoplasmic foci was independent of MT. Given the disparity of localization between Rab11A and vRNA segments in the absence of intact MT filaments, we analyzed the three-dimensional spatial relationship between Rab11A and vRNA in the cytoplasm of infected cells. We found that Rab11A and vRNA colocalization is dependent upon dynamic MT filaments. Taken together, our data suggest that cytoplasmic transport of influenza vRNA may include a Rab11A RE-independent mechanism. IMPORTANCE IAV infections cause a large public health burden through seasonal epidemics and sporadic pandemics. Pandemic IAVs emerge through reassortment of vRNA in animal or human hosts. Elucidation of the mechanism of intracellular dynamics of IAV assembly is necessary to understand reassortment. Our results describing the role of MT in vRNA transport and assembly expand upon previous studies characterizing vRNA assembly. This study is the first to assess the role of MT in influenza virus replication in human bronchial airway epithelial cells. In addition, we present novel data on the role of MT in facilitating the association between distinct vRNA segments. Interestingly, our results suggest that progressive assembly of vRNA segments may be cell type dependent and that vRNA may be transported through the cytoplasm without Rab11A RE in the absence of intact MT. These results enhance our understanding of vRNA assembly and the role of cytoskeletal proteins in that process.

scholarly journals VAMP8-dependent fusion of recycling endosomes with the plasma membrane facilitates T lymphocyte cytotoxicity

2015 ◽  
Vol 210 (1) ◽  
pp. 135-151 ◽  
Author(s):  
Misty R. Marshall ◽  
Varsha Pattu ◽  
Mahantappa Halimani ◽  
Monika Maier-Peuschel ◽  
Martha-Lena Müller ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Types ◽  
Snare Proteins ◽  
Recycling Endosome ◽  
Granule Exocytosis ◽  
Recycling Endosomes ◽  
Immune Synapses ◽  
Lymphocyte Cytotoxicity ◽  
Cytotoxic Granule

Cytotoxic T lymphocytes (CTLs) eliminate infected and neoplastic cells through directed release of cytotoxic granule contents. Although multiple SNARE proteins have been implicated in cytotoxic granule exocytosis, the role of vesicular SNARE proteins, i.e., vesicle-associated membrane proteins (VAMPs), remains enigmatic. VAMP8 was posited to represent the cytotoxic granule vesicular SNARE protein mediating exocytosis in mice. In primary human CTLs, however, VAMP8 colocalized with Rab11a-positive recycling endosomes. Upon stimulation, these endosomes rapidly trafficked to and fused with the plasma membrane, preceding fusion of cytotoxic granules. Knockdown of VAMP8 blocked both recycling endosome and cytotoxic granule fusion at immune synapses, without affecting activating signaling. Mechanistically, VAMP8-dependent recycling endosomes deposited syntaxin-11 at immune synapses, facilitating assembly of plasma membrane SNARE complexes for cytotoxic granule fusion. Hence, cytotoxic granule exocytosis is a sequential, multivesicle fusion process requiring VAMP8-mediated recycling endosome fusion before cytotoxic granule fusion. Our findings imply that secretory granule exocytosis pathways in other cell types may also be more complex than previously appreciated.

scholarly journals Laminin-binding integrins and their tetraspanin partners as potential antimetastatic targets

2010 ◽  
Vol 12 ◽  
Author(s):  
Christopher S. Stipp
Keyword(s):  
Plasma Membrane ◽  
Cell Types ◽  
Cell Junctions ◽  
Control Mechanisms ◽  
Membrane Domains ◽  
The Stability ◽  
Different Cell Types ◽  
Integrin Family ◽  
Laminin Binding

Within the integrin family of cell adhesion receptors, integrins α3β1, α6β1, α6β4 and α7β1 make up a laminin-binding subfamily. The literature is divided on the role of these laminin-binding integrins in metastasis, with different studies indicating either pro- or antimetastatic functions. The opposing roles of the laminin-binding integrins in different settings might derive in part from their unusually robust associations with tetraspanin proteins. Tetraspanins organise integrins into multiprotein complexes within discrete plasma membrane domains termed tetraspanin-enriched microdomains (TEMs). TEM association is crucial to the strikingly rapid cell migration mediated by some of the laminin-binding integrins. However, emerging data suggest that laminin-binding integrins also promote the stability of E-cadherin-based cell–cell junctions, and that tetraspanins are essential for this function as well. Thus, TEM association endows the laminin-binding integrins with both pro-invasive functions (rapid migration) and anti-invasive functions (stable cell junctions), and the composition of TEMs in different cell types might help determine the balance between these opposing activities. Unravelling the tetraspanin control mechanisms that regulate laminin-binding integrins will help to define the settings where inhibiting the function of these integrins would be helpful rather than harmful, and may create opportunities to modulate integrin activity in more sophisticated ways than simple functional blockade.

scholarly journals Plasma Membrane Microdomains Act as Concentration Platforms to Facilitate Intoxication by Aerolysin

1999 ◽  
Vol 147 (1) ◽  
pp. 175-184 ◽  
Author(s):  
Laurence Abrami ◽  
F. Gisou van der Goot
Keyword(s):  
Plasma Membrane ◽  
Target Cell ◽  
Soluble Protein ◽  
Cell Types ◽  
Living Cells ◽  
Membrane Microdomains ◽  
Toxin Concentration ◽  
Glycosyl Phosphatidylinositol ◽  
Plasma Membrane Microdomains

It has been proposed that the plasma membrane of many cell types contains cholesterol-sphingolipid–rich microdomains. Here, we analyze the role of these microdomains in promoting oligomerization of the bacterial pore-forming toxin aerolysin. Aeroly-sin binds to cells, via glycosyl phosphatidylinositol- anchored receptors, as a hydrophilic soluble protein that must polymerize into an amphipathic ring-like complex to form a pore. We first show that oligomerization can occur at >105-fold lower toxin concentration at the surface of living cells than in solution. Our observations indicate that it is not merely the number of receptors on the target cell that is important for toxin sensitivity, but their ability to associate transiently with detergent resistant microdomains. Oligomerization appears to be promoted by the fact that the toxin bound to its glycosyl phosphatidylinositol-anchored receptors, can be recruited into these microdomains, which act as concentration devices.

The C type natriuretic peptide receptor tethers AHNAK1 at the plasma membrane to potentiate arachidonic acid-induced calcium mobilization

2009 ◽  
Vol 297 (5) ◽  
pp. C1157-C1167 ◽  
Author(s):  
Abdel A. Alli ◽  
William R. Gower
Keyword(s):  
Arachidonic Acid ◽  
Plasma Membrane ◽  
Intracellular Calcium ◽  
Natriuretic Peptide ◽  
Cell Types ◽  
Calcium Mobilization ◽  
Natriuretic Peptide Receptor ◽  
Peptide Receptor ◽  
Intracellular Calcium Mobilization

Arachidonic acid (AA) liberated from membrane phospholipids is known to activate phospholipase C γ1 (PLCγ1) concurrently with AHNAK in nonneuronal cells. The recruitment of AHNAK from the nucleus is required for it to activate PLCγ1 at the plasma membrane. Here, we identify the C-type natriuretic peptide receptor (NPR-C), an atypical G protein-coupled receptor, as a protein binding partner for AHNAK1 in various cell types. Mass spectrometry and MASCOT analysis of excised bands from NPR-C immunoprecipitation studies revealed multiple signature peptides corresponding to AHNAK1. Glutathione S-transferase (GST) pulldown assays using GST- AHNAK1 fusion proteins corresponding to each of the distinct domains of AHNAK1 showed the C1 domain of AHNAK1 associates with NPR-C. The role of NPR-C in mediating AA-dependent AHNAK1 calcium signaling was explored in various cell types, including 3T3-L1 preadipocytes during the early stages of differentiation. Sucrose density gradient centrifugation studies showed AHNAK1 resides in the nucleus, cytoplasm, and at the plasma membrane, but small interfering RNA (siRNA)-mediated knockdown of NPR-C resulted in AHNAK1 accumulation in the nucleus. Overexpression of a portion of AHNAK1 resulted in augmentation of intracellular calcium mobilization, whereas siRNA-mediated knockdown of NPR-C or AHNAK1 protein resulted in attenuation of intracellular calcium mobilization in response to phorbol 12-myristate 13-acetate. We characterize the novel association between AHNAK1 and NPR-C and provide evidence that this association potentiates the AA-induced mobilization of intracellular calcium. We address the role of intracellular calcium in the various cell types that AHNAK1 and NPR-C were found to associate.

Effect of Calcium on the Growth and Differentiation of Cultured Rat Esophageal Epithelial Cells

1982 ◽  
Vol 40 ◽  
pp. 132-133
Author(s):  
W.T. Gunning ◽  
M.R. Marino ◽  
M.S. Babcock ◽  
G.D. Stoner
Keyword(s):  
Epithelial Cells ◽  
Cell Types ◽  
Replication Rate ◽  
Enzymatic Dissociation ◽  
Growth Assay ◽  
Epidermal Growth ◽  
Fetal Bovine ◽  
Esophageal Epithelial Cells ◽  
Cellular Replication

The role of calcium in modulating cellular replication and differentiation has been described for various cell types. In the present study, the effects of Ca++ on the growth and differentiation of cultured rat esophageal epithelial cells was investigated.Epithelial cells were isolated from esophagi taken from 8 week-old male CDF rats by the enzymatic dissociation method of Kaighn. The cells were cultured in PFMR-4 medium supplemented with 0.25 mg/ml dialyzed fetal bovine serum, 5 ng/ml epidermal growth factor, 10-6 M hydrocortisone 10-6 M phosphoethanolamine, 10-6 M ethanolamine, 5 pg/ml insulin, 5 ng/ml transferrin, 10 ng/ml cholera toxin and 50 ng/ml garamycin at 36.5°C in a humidified atmosphere of 3% CO2 in air. At weekly intervals, the cells were subcultured with a solution containing 1% polyvinylpyrrolidone, 0.01% EGTA, and 0.05% trypsin. After various passages, the replication rate of the cells in PFMR-4 medium containing from 10-6 M to 10-3 M Ca++ was determined using a clonal growth assay.

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