Receptor tyrosine kinases mediate epithelial Na+ channel inhibition by epidermal growth factor

2005 ◽  
Vol 288 (1) ◽  
pp. F150-F161 ◽  
Author(s):  
Qiusheng Tong ◽  
James D. Stockand
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinases ◽  
Egf Receptor ◽  
Receptor Tyrosine Kinases ◽  
Na Channel ◽  
Distal Nephron ◽  
Open Probability ◽  
Channel Inhibition ◽  
Epidermal Growth

Epidermal growth factor (EGF) decreases Na+ reabsorption across distal nephron epithelia. Activity of the epithelial Na+ channel (ENaC) is limiting for Na+ transport in this portion of the nephron. Abnormal ENaC activity and EGF signaling are both associated with polycystic kidney disease localized to the distal nephron. We tested here whether EGF and other ligands for receptor tyrosine kinases (RTK) decrease ENaC activity. EGF markedly and quickly decreased ENaC activity. The RTK inhibitor erbstatin blocked EGF actions on ENaC and when added alone increased channel activity, uncovering basal suppression by endogenous RTK. The protein tyrosine phosphatase inhibitor vanadate, similar to EGF, decreased ENaC activity. Growth factors and vanadate decreased ENaC activity by decreasing open probability. ENaC was not phosphorylated in response to EGF, indicating that intermediary proteins transduce the inhibitory signal from the EGF receptor (EGFR) to ENaC. We find that neither MAPK 1/2 nor c-Src is signaling intermediaries between EGFR and ENaC. Inhibition of ENaC paralleled decreases in plasma membrane phosphatidylinositol 4,5- bisphosphate levels [PtdIns(4,5)P2] and was abolished by clamping PtdIns(4,5)P2. We conclude that EGF and other ligands for RTK decrease ENaC open probability by decreasing membrane PtdIns(4,5)P2 levels.

An epidermal growth factor receptor/ret chimera generates mitogenic and transforming signals: evidence for a ret-specific signaling pathway

1994 ◽  
Vol 14 (1) ◽  
pp. 663-675
Author(s):  
M Santoro ◽  
W T Wong ◽  
P Aroca ◽  
E Santos ◽  
B Matoskova ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinases ◽  
Mammalian Cells ◽  
Egf Receptor ◽  
Biological Effects ◽  
Ectopic Expression ◽  
Growth Factor Receptor ◽  
Dependent Signal ◽  
Epidermal Growth

A chimeric expression vector which encoded for a molecule encompassing the extracellular domain of the epidermal growth factor (EGF) receptor (EGFR) and the intracellular domain of the ret kinase (EGFR/ret chimera) was generated. Upon ectopic expression in mammalian cells, the EGFR/ret chimera was correctly synthesized and transported to the cell surface, where it was shown capable of binding EGF and transducing an EGF-dependent signal intracellularly. Thus, the EGFR/ret chimera allows us to study the biological effects and biochemical activities of the ret kinase under controlled conditions of activation. Comparative analysis of the growth-promoting activity of the EGFR/ret chimera expressed in fibroblastic or hematopoietic cells revealed a biological phenotype clearly distinguishable from that of the EGFR, indicating that the two kinases couple with mitogenic pathways which are different to some extent. Analysis of biochemical pathways implicated in the transduction of mitogenic signals also evidenced significant differences between the ret kinase and other receptor tyrosine kinases. Thus, the sum of our results indicates the existence of a ret-specific pathway of mitogenic signaling.

Processing and targeting of proteins in the eucaryote

1988 ◽  
Vol 66 (12) ◽  
pp. 1253-1257 ◽  
Author(s):  
J. J. M. Bergeron
Keyword(s):  
Endoplasmic Reticulum ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Golgi Apparatus ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Endoplasmic Reticulum Membrane ◽  
Extracellular Milieu ◽  
Epidermal Growth ◽  
Selective Processing

Cell-free systems have helped to elucidate the molecular constituents regulating the selection and translocation of proteins into and across the endoplasmic reticulum membrane, chloroplasts, mitochondria, and peroxisomes, the transport to and through the Golgi apparatus, and the sorting of proteins to the lysosomes, the plasmalemma, and the extracellular milieu. The use of cell-free systems has also been instrumental in defining the endosomal apparatus and its functional significance in the sorting of incoming ligands and receptors, the selective processing of internalized ligands such as insulin, and transmembrane signalling, especially of the epidermal growth factor and insulin receptor tyrosine kinases. Predicted use of cell-free systems to study interorganelle relationships may help to identify the majority of molecular constituents regulating membrane traffic in the eucaryote.

scholarly journals Role of Phosphoinositide 3-Kinase in Activation of Ras and Mitogen-Activated Protein Kinase by Epidermal Growth Factor

1999 ◽  
Vol 19 (6) ◽  
pp. 4279-4288 ◽  
Author(s):  
Stefan Wennström ◽  
Julian Downward
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Map Kinase ◽  
Tyrosine Kinases ◽  
Kinase Inhibitors ◽  
Egf Receptor ◽  
Mitogen Activated Protein Kinase ◽  
Ras Activation ◽  
Mitogen Activated Protein ◽  
Epidermal Growth

ABSTRACT The paradigm for activation of Ras and extracellular signal-regulated kinase (ERK)/mitogen-activated protein (MAP) kinase by extracellular stimuli via tyrosine kinases, Shc, Grb2, and Sos does not encompass an obvious role for phosphoinositide (PI) 3-kinase, and yet inhibitors of this lipid kinase family have been shown to block the ERK/MAP kinase signalling pathway under certain circumstances. Here we show that in COS cells activation of both endogenous ERK2 and Ras by low, but not high, concentrations of epidermal growth factor (EGF) is suppressed by PI 3-kinase inhibitors; since Ras activation is less susceptible than ERK2 activation, PI 3-kinase-sensitive events may occur both upstream of Ras and between Ras and ERK2. However, strong elevation of PI 3-kinase lipid product levels by expression of membrane-targeted p110α is by itself never sufficient to activate Ras or ERK2. PI 3-kinase inhibition does not affect EGF-induced receptor autophosphorylation or adapter protein phosphorylation or complex formation. The concentrations of EGF for which PI 3-kinase inhibitors block Ras activation induce formation of Shc-Grb2 complexes but not detectable EGF receptor phosphorylation and do not activate PI 3-kinase. The activation of Ras by low, but mitogenic, concentrations of EGF is therefore dependent on basal, rather than stimulated, PI 3-kinase activity; the inhibitory effects of LY294002 and wortmannin are due to their ability to reduce the activity of PI 3-kinase to below the level in a quiescent cell and reflect a permissive rather than an upstream regulatory role for PI 3-kinase in Ras activation in this system.

Conformational Analysis of the Phosphorylated Epidermal Growth Factor Receptor

1999 ◽  
Vol 19 (5) ◽  
pp. 397-402 ◽  
Author(s):  
Anupam Bishayee ◽  
Laura Beguinot ◽  
Subal Bishayee
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Conformational Changes ◽  
Tyrosine Kinases ◽  
Egf Receptor ◽  
Receptor Tyrosine Kinases ◽  
Growth Factor Receptor ◽  
Tyrosine Residue ◽  
Peptide Antibody ◽  
Epidermal Growth

Phosphorylation-induced conformational changes have been well documented with different receptor tyrosine kinases. However, the susceptible epitopes and the tyrosine residue(s) involved in particular structural alteration mostly remain to be determined. Using a conformation-specific anti-peptide antibody, we have not only identified one such domain in the C-terminal tail of the EGF receptor but also identified the phosphate acceptor sites that are involved in the conformational change.

scholarly journals Isatin-Hydrazones with Multiple Receptor Tyrosine Kinases (RTKs) Inhibitory Activity and In-Silico Binding Mechanism

2021 ◽  
Vol 11 (9) ◽  
pp. 3746
Author(s):  
Huda S. Al-Salem ◽  
Md Arifuzzaman ◽  
Iman S. Issa ◽  
A. F. M. Motiur Rahman
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Inhibitory Activity ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Growth Factor Receptor ◽  
Competitive Inhibitors ◽  
Epidermal Growth ◽  
Multiple Receptor

Recently, we have reported a series of isatin hydrazone, two of them, namely, 3-((2,6-dichlorobenzylidene)hydrazono)indolin-2-one (1) and 3-((2-chloro-6-fluorobenzylidene)hydrazono)indolin-2-one (2) having potent cytotoxicity, showing cyclin-dependent kinases (CDK2) inhibitory activity and bearing recommended drug likeness properties. Since both compounds (1 and 2) showed inhibitory activity against CDK2, we assumed it would also have multiple receptor tyrosine kinases (RTKs) inhibitory activity. Considering those points, here, above-mentioned two isatin hydrazone 1 and 2 were synthesized using previously reported method for further investigation of their potency on RTKs (EGFR, VEGFR-2 and FLT-3) inhibitory activity. As expected, Compound 1 exhibited excellent inhibitory activity against epidermal growth factor receptor (EGFR, IC50 = 0.269 µM), vascular epidermal growth factor receptor 2 (VEGFR-2, IC50 = 0.232 µM) and FMS-like tyrosine kinase-3 (FLT-3, IC50 = 1.535 µM) tyrosine kinases. On the other hand, Compound 2 also exhibited excellent inhibitory activity against EGFR (IC50 = 0.369 µM), VEGFR-2 (IC50 = 0.266 µM) and FLT-3 (IC50 = 0.546 µM) tyrosine kinases. A molecular docking study with EGFR, VEGFR-2 and FLT-3 kinase suggested that both compounds act as type I ATP competitive inhibitors against EGFR and VEGFR-2, and type II ATP non-competitive inhibitors against FLT-3.

scholarly journals Regulation of epidermal growth factor receptor signaling by clathrin-coated membrane microdomains

2021 ◽  
Author(s):  
Camilo Garay
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Tyrosine Kinases ◽  
Egf Receptor ◽  
Akt Signaling ◽  
Membrane Microdomains ◽  
Egfr Signaling ◽  
Coated Pits ◽  
Akt Phosphorylation ◽  
Epidermal Growth

The phosphatidylinositol-3-kinase (PI3K)-Akt signaling axis controls cell survival, proliferation and metabolism, and is activated by receptor tyrosine kinases (RTKs) such as the epidermal growth factor (EGF) receptor (EGFR). In addition to activation of PI3K-Akt signaling, the binding of EGF to its receptor results in rapid recruitment of EGFR to clathrin-coated pits (CCPs) followed by eventual EGFR internalization. Hence, receptor-proximal activation of signaling intermediates occurs while EGFR resides within CCPs; however, whether CCPs are required for EGFR signaling remains poorly understood. Using a combination of pharmacological inhibition and siRNA gene silencing of clathrin, we have examined how clathrin controls EGF-stimulated activation of Akt. We find that perturbation of clathrin, but not of EGFR endocytosis by perturbation of dynamin leads to disruption of EGF-stimulated Akt phosphorylation. This indicates that clathrin acts in a function separate from its role in endocytosis to regulate EGFR signaling at the plasma membrane. The EGF-stimulated phosphorylation of the signaling intermediate Gab1, but not that of EGFR itself, was also abrogated upon disruption of clathrin. We then utilized total internal reflection fluorescence microscopy (TIRF-M) to examine the hierarchy of recruitment of EGFR signaling components to CCPs. Collectively, these findings suggest a role for clathrin as a central regulator of EGFR signaling leading to Gab1 and Akt phosphorylation.

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