RLIP76, an effector of the GTPase Ral, interacts with the AP2 complex: involvement of the Ral pathway in receptor endocytosis

2000 ◽  
Vol 113 (16) ◽  
pp. 2837-2844 ◽  
Author(s):  
V. Jullien-Flores ◽  
Y. Mahe ◽  
G. Mirey ◽  
C. Leprince ◽  
B. Meunier-Bisceuil ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Growth Factor ◽  
Egf Receptor ◽  
The Other ◽  
Ras Signaling ◽  
Receptor Endocytosis ◽  
Epidermal Growth ◽  
Two Hybrid

RLIP76 is a modular protein that was identified as a putative effector of Ral, a GTPase activated during Ras signaling. To explore further the contribution of the Ral-RLIP76 pathway to Ras signaling, we have looked for partners of RLIP76. Mu2, the medium chain of the AP2 complex is shown to interact with RLIP76. We show also that in vivo endogenous AP2 and RLIP76 form a complex and that this in vivo interaction is independent of cells being stimulated by a growth factor. Furthermore, RLIP76 differentiates AP2 from AP1 in vivo as RLIP76 differentiates mu2 from mu1 in vitro and in two hybrid assays. We show that activated Ral interferes with both tranferrin receptor endocytosis and epidermal growth factor (EGF) receptor endocytosis in HeLa cells. We propose a model where the Ral-RLIP76 pathway connects signal transduction and endocytosis through interaction on one hand between the Ras-Ral pathway and RLIP, on the other hand between RLIP and proteins belonging to the endocytotic machinery.

scholarly journals Differential Downregulation of E-Cadherin and Desmoglein by Epidermal Growth Factor

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Miquella G. Chavez ◽  
Christian A. Buhr ◽  
Whitney K. Petrie ◽  
Angela Wandinger-Ness ◽  
Donna F. Kusewitt ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Wound Repair ◽  
Egf Receptor ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Epidermal Growth ◽  
E Cadherin

Modulation of cell : cell junctions is a key event in cutaneous wound repair. In this study we report that activation of the epidermal growth factor (EGF) receptor disrupts cel : cell adhesion, but with different kinetics and fates for the desmosomal cadherin desmoglein and for E-cadherin. Downregulation of desmoglein preceded that of E-cadherinin vivoand in an EGF-stimulatedin vitrowound reepithelialization model. Dual immunofluorescence staining revealed that neither E-cadherin nor desmoglein-2 internalized with the EGF receptor, or with one another. In response to EGF, desmoglein-2 entered a recycling compartment based on predominant colocalization with the recycling marker Rab11. In contrast, E-cadherin downregulation was accompanied by cleavage of the extracellular domain. A broad-spectrum matrix metalloproteinase inhibitor protected E-cadherin but not the desmosomal cadherin, desmoglein-2, from EGF-stimulated disruption. These findings demonstrate that although activation of the EGF receptor regulates adherens junction and desmosomal components, this stimulus downregulates associated cadherins through different mechanisms.

scholarly journals Targeted Antiepidermal Growth Factor Receptor (Cetuximab) Immunoliposomes Enhance Cellular Uptake In Vitro and Exhibit Increased Accumulation in an Intracranial Model of Glioblastoma Multiforme

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Joachim Høg Mortensen ◽  
Maria Jeppesen ◽  
Linda Pilgaard ◽  
Ralf Agger ◽  
Meg Duroux ◽  
...  
Keyword(s):  
Growth Factor ◽  
Glioblastoma Multiforme ◽  
Egf Receptor ◽  
Xenograft Model ◽  
Growth Factor Receptor ◽  
Liposomal Formulations ◽  
Cancer Types ◽  
Epidermal Growth

Therapeutic advances do not circumvent the devastating fact that the survival rate in glioblastoma multiforme (GBM) is less than 5%. Nanoparticles consisting of liposome-based therapeutics are provided against a variety of cancer types including GBM, but available liposomal formulations are provided without targeting moieties, which increases the dosing demands to reach therapeutic concentrations with risks of side effects. We prepared PEGylated immunoliposomes (ILs) conjugated with anti-human epidermal growth factor receptor (EGFR) antibodies Cetuximab (α-hEGFR-ILs). The affinity of the α-hEGFR-ILs for the EGF receptor was evaluated in vitro using U87 mg and U251 mg cells and in vivo using an intracranial U87 mg xenograft model. The xenograft model was additionally analyzed with respect to permeability to endogenous albumin, tumor size, and vascularization. The in vitro studies revealed significantly higher binding of α-hEGFR-ILs when compared with liposomes conjugated with isotypic nonimmune immunoglobulin. The uptake and internalization of the α-hEGFR-ILs by U87 mg cells were further confirmed by 3D deconvolution analyses. In vivo, the α-hEGFR-ILs accumulated to a higher extent inside the tumor when compared to nonimmune liposomes. The data show that α-hEGFR-ILs significantly enhance the uptake and accumulation of liposomes in this experimental model of GBM suggestive of improved specific nanoparticle-based delivery.

scholarly journals Coronavirus Genetically Redirected to the Epidermal Growth Factor Receptor Exhibits Effective Antitumor Activity against a Malignant Glioblastoma

2009 ◽  
Vol 83 (15) ◽  
pp. 7507-7516 ◽  
Author(s):  
Monique H. Verheije ◽  
Martine L. M. Lamfers ◽  
Thomas Würdinger ◽  
Guy C. M. Grinwis ◽  
Winald R. Gerritsen ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Human Tumor ◽  
Adaptor Protein ◽  
Progeny Virus ◽  
Epidermal Growth ◽  
Positive Strand Rna

ABSTRACT Coronaviruses are positive-strand RNA viruses with features attractive for oncolytic therapy. To investigate this potential, we redirected the coronavirus murine hepatitis virus (MHV), which is normally unable to infect human cells, to human tumor cells by using a soluble receptor (soR)-based expression construct fused to an epidermal growth factor (EGF) receptor targeting moiety. Addition of this adapter protein to MHV allowed infection of otherwise nonsusceptible, EGF receptor (EGFR)-expressing cell cultures. We introduced the sequence encoding the adaptor protein soR-EGF into the MHV genome to generate a self-targeted virus capable of multiround infection. The resulting recombinant MHV was viable and had indeed acquired the ability to infect all glioblastoma cell lines tested in vitro. Infection of malignant human glioblastoma U87ΔEGFR cells gave rise to release of progeny virus and efficient cell killing in vitro. To investigate the oncolytic capacity of the virus in vivo, we used an orthotopic U87ΔEGFR xenograft mouse model. Treatment of mice bearing a lethal intracranial U87ΔEGFR tumor by injection with MHVsoR-EGF significantly prolonged survival compared to phosphate-buffered saline-treated (P = 0.001) and control virus-treated (P = 0.004) animals, and no recurrent tumor load was observed. However, some adverse effects were seen in normal mouse brain tissues that were likely caused by the natural murine tropism of MHV. This is the first demonstration of oncolytic activity of a coronavirus in vivo. It suggests that nonhuman coronaviruses may be attractive new therapeutic agents against human tumors.

scholarly journals The epidermal growth factor receptor phosphorylates GTPase-activating protein (GAP) at Tyr-460, adjacent to the GAP SH2 domains.

1991 ◽  
Vol 11 (5) ◽  
pp. 2511-2516 ◽  
Author(s):  
X Q Liu ◽  
T Pawson
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Egf Receptor ◽  
Sh2 Domain ◽  
Ras Signaling ◽  
Gtpase Activating Protein ◽  
Epidermal Growth

GTPase-activating protein (GAP) stimulates the ability of p21ras to hydrolyze GTP to GDP. Since GAP is phosphorylated by a variety of activated or oncogenic protein-tyrosine kinases, it may couple tyrosine kinases to the Ras signaling pathway. The epidermal growth factor (EGF) receptor cytoplasmic domain phosphorylated human GAP in vitro within a single tryptic phosphopeptide. The same GAP peptide was also apparently phosphorylated on tyrosine in EGF-stimulated rat fibroblasts. Circumstantial evidence suggested that residue 460 might be the site of GAP tyrosine phosphorylation. This possibility was confirmed by phosphorylation of a synthetic peptide corresponding to the predicted tryptic peptide containing Tyr-460. Alteration of Tyr-460 to phenylalanine by site-directed mutagenesis diminished the in vitro phosphorylation of a bacterial GAP polypeptide by the EGF receptor. We conclude that Tyr-460 is a site of GAP tyrosine phosphorylation by the EGF receptor in vitro and likely in vivo. GAP Tyr-460 is located immediately C terminal to the second GAP SH2 domain, suggesting that its phosphorylation might have a role in regulating protein-protein interactions.

The epidermal growth factor receptor phosphorylates GTPase-activating protein (GAP) at Tyr-460, adjacent to the GAP SH2 domains

1991 ◽  
Vol 11 (5) ◽  
pp. 2511-2516 ◽  
Author(s):  
X Q Liu ◽  
T Pawson
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Egf Receptor ◽  
Sh2 Domain ◽  
Ras Signaling ◽  
Gtpase Activating Protein ◽  
Epidermal Growth

GTPase-activating protein (GAP) stimulates the ability of p21ras to hydrolyze GTP to GDP. Since GAP is phosphorylated by a variety of activated or oncogenic protein-tyrosine kinases, it may couple tyrosine kinases to the Ras signaling pathway. The epidermal growth factor (EGF) receptor cytoplasmic domain phosphorylated human GAP in vitro within a single tryptic phosphopeptide. The same GAP peptide was also apparently phosphorylated on tyrosine in EGF-stimulated rat fibroblasts. Circumstantial evidence suggested that residue 460 might be the site of GAP tyrosine phosphorylation. This possibility was confirmed by phosphorylation of a synthetic peptide corresponding to the predicted tryptic peptide containing Tyr-460. Alteration of Tyr-460 to phenylalanine by site-directed mutagenesis diminished the in vitro phosphorylation of a bacterial GAP polypeptide by the EGF receptor. We conclude that Tyr-460 is a site of GAP tyrosine phosphorylation by the EGF receptor in vitro and likely in vivo. GAP Tyr-460 is located immediately C terminal to the second GAP SH2 domain, suggesting that its phosphorylation might have a role in regulating protein-protein interactions.

scholarly journals Oligosaccharide G19 inhibits U-87 MG human glioma cells growth in vitro and in vivo by targeting epidermal growth factor (EGF) and activating p53/p21 signaling

Glycobiology ◽  
2014 ◽  
Vol 24 (8) ◽  
pp. 748-765 ◽  
Author(s):  
Hailing Liu ◽  
Ling Zhou ◽  
Songshan Shi ◽  
Ying Wang ◽  
Xinyan Ni ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Glioma Cells ◽  
Human Glioma ◽  
Human Glioma Cells ◽  
Epidermal Growth
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