scholarly journals Recruitment of epidermal growth factor receptors into coated pits requires their activated tyrosine kinase.

1995 ◽  
Vol 129 (1) ◽  
pp. 47-54 ◽  
Author(s):  
C Lamaze ◽  
S L Schmid
Keyword(s):  
Tyrosine Kinase ◽  
Egf Receptor ◽  
Epidermal Growth Factor Receptors ◽  
Deletion Mutants ◽  
Functional Assay ◽  
Wild Type ◽  
Coated Pits ◽  
Kinase Substrate ◽  
A Cell ◽  
Epidermal Growth

EGF-receptor (EGF-R) tyrosine kinase is required for the down-regulation of activated EGF-R. However, controversy exists as to whether ligand-induced activation of the EGF-R tyrosine kinase is required for internalization or for lysosomal targeting. We have addressed this issue using a cell-free assay that selectively measures the recruitment of EGF-R into coated pits. Here we show that EGF bound to wild-type receptors is efficiently sequestered in coated pits. In contrast, sequestration of kinase-deficient receptors occurs inefficiently and at the same basal rate of endocytosis of unoccupied receptors or receptors lacking any cytoplasmic domain. Sequestration of deletion mutants of the EGF-R that lack autophosphorylation sites also requires an active tyrosine kinase. This suggests that a tyrosine kinase substrate(s) other than the EGF-R itself, is required for its efficient ligand-induced recruitment into coated pits. Addition of a soluble EGF-R tyrosine kinase fully and specifically restores the recruitment of kinase-deficient EGF-R into coated pits providing a powerful functional assay for identification of these substrate(s).

A mutant epidermal growth factor receptor with defective protein tyrosine kinase is unable to stimulate proto-oncogene expression and DNA synthesis

1987 ◽  
Vol 7 (12) ◽  
pp. 4568-4571
Author(s):  
A M Honegger ◽  
D Szapary ◽  
A Schmidt ◽  
R Lyall ◽  
E Van Obberghen ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Egf Receptor ◽  
Wild Type ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine ◽  
Epidermal Growth ◽  
Protein Tyrosine Kinase Activity ◽  
Stimulation Of

Cultured NIH-3T3 cells devoid of endogenous epidermal growth factor (EGF) receptors were transfected with cDNA expression constructs encoding either normal human EGF receptor or a receptor mutated in vitro at Lys-721, a residue that is thought to function as part of the ATP-binding site of the kinase domain. Unlike the wild-type EGF-receptor expressed in these cells, which exhibited EGF-dependent protein tyrosine kinase activity, the mutant receptor lacked protein tyrosine kinase activity and was unable to undergo autophosphorylation and to phosphorylate exogenous substrates. Despite this deficiency, the mutant receptor was normally expressed on the cell surface, and it exhibited both high- and low-affinity binding sites. The addition of EGF to cells expressing wild-type receptors caused the stimulation of various responses, including enhanced expression of proto-oncogenes c-fos and c-myc, morphological changes, and stimulation of DNA synthesis. However, in cells expressing mutant receptors, EGF was unable to stimulate these responses, suggesting that the tyrosine kinase activity is essential for EGF receptor signal transduction.

scholarly journals A mutant epidermal growth factor receptor with defective protein tyrosine kinase is unable to stimulate proto-oncogene expression and DNA synthesis.

1987 ◽  
Vol 7 (12) ◽  
pp. 4568-4571 ◽  
Author(s):  
A M Honegger ◽  
D Szapary ◽  
A Schmidt ◽  
R Lyall ◽  
E Van Obberghen ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Protein Tyrosine Kinase ◽  
Kinase Activity ◽  
Egf Receptor ◽  
Wild Type ◽  
Tyrosine Kinase Activity ◽  
Protein Tyrosine ◽  
Epidermal Growth ◽  
Protein Tyrosine Kinase Activity ◽  
Stimulation Of

Cultured NIH-3T3 cells devoid of endogenous epidermal growth factor (EGF) receptors were transfected with cDNA expression constructs encoding either normal human EGF receptor or a receptor mutated in vitro at Lys-721, a residue that is thought to function as part of the ATP-binding site of the kinase domain. Unlike the wild-type EGF-receptor expressed in these cells, which exhibited EGF-dependent protein tyrosine kinase activity, the mutant receptor lacked protein tyrosine kinase activity and was unable to undergo autophosphorylation and to phosphorylate exogenous substrates. Despite this deficiency, the mutant receptor was normally expressed on the cell surface, and it exhibited both high- and low-affinity binding sites. The addition of EGF to cells expressing wild-type receptors caused the stimulation of various responses, including enhanced expression of proto-oncogenes c-fos and c-myc, morphological changes, and stimulation of DNA synthesis. However, in cells expressing mutant receptors, EGF was unable to stimulate these responses, suggesting that the tyrosine kinase activity is essential for EGF receptor signal transduction.

scholarly journals Activation of the Epidermal Growth Factor (EGF) Receptor Induces Formation of EGF Receptor- and Grb2-Containing Clathrin-Coated Pits

2006 ◽  
Vol 26 (2) ◽  
pp. 389-401 ◽  
Author(s):  
Lene E. Johannessen ◽  
Nina Marie Pedersen ◽  
Ketil Winther Pedersen ◽  
Inger Helene Madshus ◽  
Espen Stang
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Point Mutations ◽  
Adaptor Protein ◽  
Mitogen Activated Protein Kinase ◽  
Coated Pits ◽  
Α Subunit ◽  
Sh3 Domains ◽  
Epidermal Growth

ABSTRACT In HeLa cells depleted of adaptor protein 2 complex (AP2) by small interfering RNA (siRNA) to the μ2 or α subunit or by transient overexpression of an AP2 sequestering mutant of Eps15, endocytosis of the transferrin receptor (TfR) was strongly inhibited. However, epidermal growth factor (EGF)-induced endocytosis of the EGF receptor (EGFR) was inhibited only in cells where the α subunit had been knocked down. By immunoelectron microscopy, we found that in AP2-depleted cells, the number of clathrin-coated pits was strongly reduced. When such cells were incubated with EGF, new coated pits were formed. These contained EGF, EGFR, clathrin, and Grb2 but not the TfR. The induced coated pits contained the α subunit, but labeling density was reduced compared to control cells. Induction of clathrin-coated pits required EGFR kinase activity. Overexpression of Grb2 with inactivating point mutations in N- or C-terminal SH3 domains or in both SH3 domains inhibited EGF-induced formation of coated pits efficiently, even though Grb2 SH3 mutations did not block activation of mitogen-activated protein kinase (MAPK) or phosphatidylinositol 3-kinase (PI3K). Our data demonstrate that EGFR-induced signaling and Grb2 are essential for formation of clathrin-coated pits accommodating the EGFR, while activation of MAPK and PI3K is not required.

scholarly journals Multiple functions of let-23, a Caenorhabditis elegans receptor tyrosine kinase gene required for vulval induction.

Genetics ◽  
1991 ◽  
Vol 128 (2) ◽  
pp. 251-267 ◽  
Author(s):  
R V Aroian ◽  
P W Sternberg
Keyword(s):  
Caenorhabditis Elegans ◽  
Tyrosine Kinase ◽  
Receptor Tyrosine Kinase ◽  
Egf Receptor ◽  
Kinase Gene ◽  
Multiple Functions ◽  
Tyrosine Kinase Gene ◽  
Receptor Tyrosine Kinase Gene ◽  
Epidermal Growth ◽  
Mutant Phenotypes

Abstract The let-23 gene, which encodes a putative tyrosine kinase of the epidermal growth factor (EGF) receptor subfamily, has multiple functions during Caenorhabditis elegans development. We show that let-23 function is required for vulval precursor cells (VPCs) to respond to the signal that induces vulval differentiation: a complete loss of let-23 function results in no induction. However, some let-23 mutations that genetically reduce but do not eliminate let-23 function result in VPCs apparently hypersensitive to inductive signal: as many as five of six VPCs can adopt vulval fates, in contrast to the three that normally do. These results suggest that the let-23 receptor tyrosine kinase controls two opposing pathways, one that stimulates vulval differentiation and another that negatively regulates vulval differentiation. Furthermore, analysis of 16 new let-23 mutations indicates that the let-23 kinase functions in at least five tissues. Since various let-23 mutant phenotypes can be obtained independently, the let-23 gene is likely to have tissue-specific functions.

scholarly journals Localization of Phospholipase D1 to Caveolin-enriched Membrane via Palmitoylation: Implications for Epidermal Growth Factor Signaling

2002 ◽  
Vol 13 (11) ◽  
pp. 3976-3988 ◽  
Author(s):  
Jung Min Han ◽  
Yong Kim ◽  
Jun Sung Lee ◽  
Chang Sup Lee ◽  
Byoung Dae Lee ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Point Mutations ◽  
Dominant Negative ◽  
Growth Factor Signaling ◽  
Wild Type ◽  
Caveolin 1 ◽  
Epidermal Growth ◽  
Egf Signaling

Phospholipase D (PLD) has been suggested to mediate epidermal growth factor (EGF) signaling. However, the molecular mechanism of EGF-induced PLD activation has not yet been elucidated. We investigated the importance of the phosphorylation and compartmentalization of PLD1 in EGF signaling. EGF treatment of COS-7 cells transiently expressing PLD1 stimulated PLD1 activity and induced PLD1 phosphorylation. The EGF-induced phosphorylation of threonine147 was completely blocked and the activity of PLD1 attenuated by point mutations (S2A/T147A/S561A) of PLD1 phosphorylation sites. The expression of a dominant negative PKCα mutant by adenovirus-mediated gene transfer greatly inhibited the phosphorylation and activation of PLD1 induced by EGF in PLD1-transfected COS-7 cells. EGF-induced PLD1 phosphorylation occurred primarily in the caveolin-enriched membrane (CEM) fraction, and the kinetics of PLD1 phosphorylation in the CEM were strongly correlated with PLD1 phosphorylation in the total membrane. Interestingly, EGF-induced PLD1 phosphorylation and activation and the coimmunoprecipitation of PLD1 with caveolin-1 and the EGF receptor in the CEM were significantly attenuated in the palmitoylation-deficient C240S/C241S mutant, which did not localize to the CEM. Immunocytochemical analysis revealed that wild-type PLD1 colocalized with caveolin-1 and the EGF receptor and that phosphorylated PLD1 was localized exclusively in the plasma membrane, although some PLD1 was also detected in vesicular structures. Transfection of wild-type PLD1 but not of C240S/C241S mutant increased EGF-induced raf-1 translocation to the CEM and ERK phosphorylation. This study shows, for the first time, that EGF-induced PLD1 phosphorylation and activation occur in the CEM and that the correct localization of PLD1 to the CEM via palmitoylation is critical for EGF signaling.

Ontogeny of epidermal growth factor receptor tyrosine kinase in rat liver

1991 ◽  
Vol 260 (2) ◽  
pp. G290-G298 ◽  
Author(s):  
B. K. De ◽  
T. L. Brown ◽  
F. J. Suchy
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinase ◽  
Rat Liver ◽  
Plasma Membranes ◽  
Egf Receptor ◽  
Specific Binding ◽  
Liver Plasma Membranes ◽  
Epidermal Growth ◽  
Autokinase Activity

The binding of epidermal growth factor (EGF) to its receptor and the activity of the receptor intrinsic protein-tyrosine kinase were studied during the ontogeny of rat liver. The number of EGF receptors during pre- and postnatal development was first compared in crude liver plasma membranes using 1) specific binding of 125I-labeled EGF and 2) immunoblot analysis using any antireceptor polyclonal rabbit antibody. Both methods detected the expression of the EGF receptor in fetal rat liver on day 17 of gestation, but in an amount markedly less than the adult. Within 24 h, there was a more than twofold increase in EGF binding to plasma membranes as well as a marked increase in receptor immunoreactivity. However, after birth, there was a precipitous drop in receptor number to less than 20% of the adult level by the end of the first postnatal day (P less than 0.001). Next, the presence of EGF-stimulated tyrosine kinase activity (autophosphorylation) was determined during the same stages of development. Electrophoresis of membranes phosphorylated in the presence or absence of EGF followed by autoradiography demonstrated autokinase activity stimulated by EGF in day 18 and 19 fetal liver plasma membranes, but not in membranes on day 17 of gestation. Similar to the pattern observed with EGF binding, there was a decrease in autokinase activity in early neonatal plasma membranes followed by an increase to near adult levels by 7 days postnatally. Quantitation of the amount of 32P radioactivity associated with the EGF receptor bands in each age group, correlated with the degree of autophosphorylation assessed by autoradiography.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals An endosomally localized isoform of Eps15 interacts with Hrs to mediate degradation of epidermal growth factor receptor

2008 ◽  
Vol 180 (6) ◽  
pp. 1205-1218 ◽  
Author(s):  
Ingrid Roxrud ◽  
Camilla Raiborg ◽  
Nina Marie Pedersen ◽  
Espen Stang ◽  
Harald Stenmark
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Adaptor Protein ◽  
Coated Pits ◽  
Kinase Substrate ◽  
Epidermal Growth

Down-regulation of activated and ubiquitinated growth factor (GF) receptors by endocytosis and subsequent lysosomal degradation ensures attenuation of GF signaling. The ubiquitin-binding adaptor protein Eps15 (epidermal growth factor receptor [EGFR] pathway substrate 15) functions in endocytosis of such receptors. Here, we identify an Eps15 isoform, Eps15b, and demonstrate its expression in human cells and conservation across vertebrate species. Although both Eps15 and Eps15b interact with the endosomal sorting protein Hrs (hepatocyte growth factor–regulated tyrosine kinase substrate) in vitro, we find that Hrs specifically binds Eps15b in vivo (whereas adaptor protein 2 preferentially interacts with Eps15). Although Eps15 mainly localizes to clathrin-coated pits at the plasma membrane, Eps15b localizes to Hrs-positive microdomains on endosomes. Eps15b overexpression, similarly to Hrs overexpression, inhibits ligand-mediated degradation of EGFR, whereas Eps15 is without effect. Similarly, depletion of Eps15b but not Eps15 delays degradation and promotes recycling of EGFR. These results indicate that Eps15b is an endosomally localized isoform of Eps15 that is present in the Hrs complex via direct Hrs interaction and important for the sorting function of this complex.

scholarly journals Rapid uptake of tyrphostin into A431 human epidermoid cells is followed by delayed inhibition of epidermal growth factor (EGF)-stimulated EGF receptor tyrosine kinase activity.

1991 ◽  
Vol 11 (5) ◽  
pp. 2697-2703 ◽  
Author(s):  
C A Faaland ◽  
F H Mermelstein ◽  
J Hayashi ◽  
J D Laskin
Keyword(s):  
Cell Cycle ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinase ◽  
Receptor Tyrosine Kinase ◽  
Kinase Activity ◽  
Egf Receptor ◽  
Tyrosine Kinase Activity ◽  
A431 Cells ◽  
Epidermal Growth

Treatment of A431 human epidermoid cells with epidermal growth factor (EGF; 20 nM) results in decreased proliferation. This is associated with blockage of the cells in the S and/or G2 phases of the cell cycle. We found that tyrphostin, a putative tyrosine kinase inhibitor, in the range of 50 to 100 microM, partially reversed the growth-inhibitory and cell cycle changes induced by EGF. By using high-pressure liquid chromatography with electrochemical detection, we found that tyrphostin was readily incorporated into A431 cells, reaching maximal levels within 1 h. Although tyrphostin (50 to 100 microM) had no effect on high-affinity binding of EGF to its receptor in A431 cells for up to 24 h, the compound partially inhibited EGF-stimulated EGF receptor tyrosine kinase activity. However, this effect was evident only after prolonged treatment of the cells (4 to 24 h) with the drug. When the peak intracellular concentration of tyrphostin occurred (1 h), no inhibition of tyrosine kinase activity was observed. After both 1 and 24 h, tyrphostin was a less effective inhibitor of tyrosine kinase activity than the potent tumor promoter 12-O-tetradecanoyl phorbol-13-acetate, which almost completely blocked EGF receptor autophosphorylation. On the basis of our data, we hypothesize that tyrphostin is not a competitive inhibitor of the EGF receptor tyrosine kinase in intact cells and that it functions by an indirect mechanism.

scholarly journals Epidermal-growth-factor-stimulated phosphorylation of calpactin II in membrane vesicles shed from cultured A-431 cells

1989 ◽  
Vol 259 (2) ◽  
pp. 577-583 ◽  
Author(s):  
J Blay ◽  
K A Valentine-Braun ◽  
J K Northup ◽  
M D Hollenberg
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Membrane Vesicles ◽  
Receptor Internalization ◽  
Receptor Kinase ◽  
Kinase Substrate ◽  
Epidermal Growth ◽  
Shed Vesicles ◽  
And Function

Membrane vesicles shed from intact A-431 epidermoid carcinoma cells and harvested in the presence of Ca2+ contained epidermal-growth-factor (EGF) receptor/kinase substrates of apparent molecular masses 185, 85, 70, 55, 38 and 27 kDa. The 38 kDa substrate (p38) was recognized by an antibody that had been raised against the human placental EGF receptor/kinase substrate calpactin II (lipocortin I). The A-431 and placental substrates, isolated by immunoprecipitation after phosphorylation in situ, yielded identical phosphopeptide maps upon limited proteolytic digestion with each of five different enzymes. The A-431-cell vesicular p38 is therefore calpactin II. EGF treatment of the intact A-431 cells before inducing vesiculation was not necessary for the substrate to be present within the vesicles. Our data thus indicate that receptor internalization is not a prerequisite for receptor-mediated phosphorylation of calpactin II. The ability of the protein to function as a substrate for the receptor/kinase depended upon the continued presence of Ca2+ during the vesicle-isolation procedure. EGF-stimulated phosphorylation of calpactin II was much less pronounced in vesicles prepared from A-431 cells in the absence of Ca2+, although comparable amounts of the protein were detectable by immunoblotting. Calpactin II therefore appears to be sequestered in a Ca2+-modulated manner within shed vesicles, along with at least four other major targets for the EGF receptor/kinase. The vesicle preparation may be a useful model system in which to study the phosphorylation and function of potentially important membrane-associated substrates for the receptor.

Sign in / Sign up

Export Citation Format

Share Document