scholarly journals Phosphorylation of iRhom2 at the plasma membrane controls mammalian TACE-dependent inflammatory and growth factor signalling

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Adam Graham Grieve ◽  
Hongmei Xu ◽  
Ulrike Künzel ◽  
Paul Bambrough ◽  
Boris Sieber ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Cell Surface ◽  
Secretory Pathway ◽  
Inflammatory Responses ◽  
Growth Factor Receptor ◽  
Primary Mouse ◽  
Mouse Macrophages ◽  
Growth Factor Signalling ◽  
Intercellular Signalling

Proteolytic cleavage and release from the cell surface of membrane-tethered ligands is an important mechanism of regulating intercellular signalling. TACE is a major shedding protease, responsible for the liberation of the inflammatory cytokine TNFα and ligands of the epidermal growth factor receptor. iRhoms, catalytically inactive members of the rhomboid-like superfamily, have been shown to control the ER-to-Golgi transport and maturation of TACE. Here, we reveal that iRhom2 remains associated with TACE throughout the secretory pathway, and is stabilised at the cell surface by this interaction. At the plasma membrane, ERK1/2-mediated phosphorylation and 14-3-3 protein binding of the cytoplasmic amino-terminus of iRhom2 alter its interaction with mature TACE, thereby licensing its proteolytic activity. We show that this molecular mechanism is responsible for triggering inflammatory responses in primary mouse macrophages. Overall, iRhom2 binds to TACE throughout its lifecycle, implying that iRhom2 is a primary regulator of stimulated cytokine and growth factor signalling.

scholarly journals Endosomal receptor kinetics determine the stability of intracellular growth factor signalling complexes

2007 ◽  
Vol 402 (3) ◽  
pp. 537-549 ◽  
Author(s):  
A. Rami Tzafriri ◽  
Elazer R. Edelman
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Dissociation Constant ◽  
Specific Binding ◽  
Ph Dependence ◽  
Growth Factor Receptor ◽  
Factor Binding ◽  
Receptor Complexes ◽  
Growth Factor Signalling ◽  
The Stability

There is an emerging paradigm that growth factor signalling continues in the endosome and that cell response to a growth factor is defined by the integration of cell surface and endosomal events. As activated receptors in the endosome are exposed to a different set of binding partners, they probably elicit differential signals compared with when they are at the cell surface. As such, complete appreciation of growth factor signalling requires understanding of growth factor–receptor binding and trafficking kinetics both at the cell surface and in endosomes. Growth factor binding to surface receptors is well characterized, and endosomal binding is assumed to follow surface kinetics if one accounts for changes in pH. Yet, specific binding kinetics within the endosome has not been examined in detail. To parse the factors governing the binding state of endosomal receptors we analysed a whole-cell mathematical model of epidermal growth factor receptor trafficking and binding. We discovered that the stability of growth factor–receptor complexes within endosomes is governed by three primary independent factors: the endosomal dissociation constant, total endosomal volume and the number of endosomal receptors. These factors were combined into a single dimensionless parameter that determines the endosomal binding state of the growth factor–receptor complex and can distinguish different growth factors from each other and different cell states. Our findings indicate that growth factor binding within endosomal compartments cannot be appreciated solely on the basis of the pH-dependence of the dissociation constant and that the concentration of receptors in the endosomal compartment must also be considered.

scholarly journals Epidermal Growth Factor Receptor Distribution during Chemotactic Responses

2000 ◽  
Vol 11 (11) ◽  
pp. 3873-3883 ◽  
Author(s):  
Maryse Bailly ◽  
Jeffrey Wyckoff ◽  
Boumediene Bouzahzah ◽  
Ross Hammerman ◽  
Vonetta Sylvestre ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Egf Receptor ◽  
Fluorescent Protein ◽  
Growth Factor Receptor ◽  
Spatial Gradient ◽  
Spatial Gradients ◽  
Epidermal Growth ◽  
Green Fluorescent

To determine the distribution of the epidermal growth factor (EGF) receptor (EGFR) on the surface of cells responding to EGF as a chemoattractant, an EGFR-green fluorescent protein chimera was expressed in the MTLn3 mammary carcinoma cell line. The chimera was functional and easily visualized on the cell surface. In contrast to other studies indicating that the EGFR might be localized to certain regions of the plasma membrane, we found that the chimera is homogeneously distributed on the plasma membrane and becomes most concentrated in vesicles after endocytosis. In spatial gradients of EGF, endocytosed receptor accumulates on the upgradient side of the cell. Visualization of the binding of fluorescent EGF to cells reveals that the affinity properties of the receptor, together with its expression level on cells, can provide an initial amplification step in spatial gradient sensing.

Orientation of the v-erb-B gene product in the plasma membrane

1986 ◽  
Vol 6 (4) ◽  
pp. 1329-1333
Author(s):  
R C Schatzman ◽  
G I Evan ◽  
M L Privalsky ◽  
J M Bishop
Keyword(s):  
Endoplasmic Reticulum ◽  
Epidermal Growth Factor Receptor ◽  
Plasma Membrane ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Kinase Domain ◽  
Amino Terminus ◽  
Protein Kinase Domain ◽  
Epidermal Growth

The retroviral oncogene v-erb-B encodes a truncated version of the receptor for epidermal growth factor. To define the disposition of the v-erb-B protein within cells and across the plasma membrane, we raised antibodies against defined epitopes in the protein and used these in immunofluorescence to analyze cells transformed by v-erb-B. A small fraction of the v-erb-B protein was found on the plasma membrane in a clustered configuration. The bulk of the protein was located in the endoplasmic reticulum and Golgi apparatus. Epitopes near the amino terminus of the v-erb-B protein were displayed on the surface of the cell, whereas epitopes in the protein kinase domain were located exclusively within cells. We conclude that the v-erb-B protein spans the plasma membrane in a manner similar or identical to that of the epidermal growth factor receptor, even though the viral transforming protein does not possess the signal peptide that is thought to direct insertion of the receptor into the membrane.

scholarly journals FRMD8 promotes inflammatory and growth factor signalling by stabilising the iRhom/ADAM17 sheddase complex

2018 ◽  
Author(s):  
Ulrike Künzel ◽  
Adam G. Grieve ◽  
Yao Meng ◽  
Sally A. Cowley ◽  
Matthew Freeman
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Inflammatory Cytokine ◽  
Egf Receptor ◽  
Receptor Ligands ◽  
Ferm Domain ◽  
Human Macrophages ◽  
Mouse Tissues ◽  
N Terminus ◽  
Growth Factor Signalling

AbstractMany intercellular signals are synthesised as transmembrane precursors that are released by proteolytic cleavage (‘shedding’) from the cell surface. ADAM17, a membrane-tethered metalloprotease, is the primary shedding enzyme responsible for the release of the inflammatory cytokine TNFα and several EGF receptor ligands. ADAM17 exists in complex with the rhomboid-like iRhom proteins, which act as cofactors that regulate ADAM17 substrate shedding. Here we report that the poorly characterised FERM domain-containing protein FRMD8 is a new component of iRhom2/ADAM17 sheddase complex. FRMD8 binds to the cytoplasmic N-terminus of iRhoms, and is necessary to stabilise the iRhoms and ADAM17 beyond the Golgi. In the absence of FRMD8, iRhom2 and ADAM17 are degraded via the endolysosomal pathway, resulting in the reduction of ADAM17-mediated shedding. We have confirmed the pathophysiological significance of FRMD8 in iPSC-derived human macrophages and mouse tissues, thus demonstrating its role in the regulated release of multiple cytokine and growth factor signals.

Kinetics and Regulation of Tyrosine Phosphorylation of the Platelet Derived Growth Factor Receptor

1989 ◽  
Vol 75 (4) ◽  
pp. 362-366
Author(s):  
Lilia Alberghina ◽  
Renata Zippel ◽  
Enzo Martegani ◽  
Emmapaola Sturani
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Tyrosine Phosphorylation ◽  
Growth Factor Receptor ◽  
Growth Conditions ◽  
Platelet Derived Growth Factor ◽  
Dependent Manner ◽  
Pdgf Receptor ◽  
Receptor Complexes ◽  
Phosphorylated Form

Platelet derived growth factor (PDGF) interaction with the cells induces rapid tyrosine phosphorylation of the PDGF receptor in a dose dependent manner. At 37 °C phosphorylation of the receptor is followed by its dephosphorylation and internalization. It is observed that the higher the ligand concentration, the more transient is the response, and the observed kinetics are explained by a simple kinetic model. At 4 °C the phosphorylated form of the receptor is more stable; however, if PDGF is dissociated from the cell surface-associated ligand-receptor complexes, the receptors are rapidly dephosphorylated, indicating that phosphatases specific for phosphotyrosine groups are very active within the cells. In fact, addition of orthovanadate stabilizes the phosphorylated form of the receptor and helps in recognizing possible physiological substrates of the PDGF receptor kinase. The expression of PDGF receptors on the cell surface has been investigated under different growth conditions: a positive correlation exists between the amount of PDGF receptors and the duplication times of exponentially growing cultures. Moreover, during exponential growth the PDGF receptors are scarcely expressed, and their number increases reaching a maximal value when the population enters the stationary phase.

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