scholarly journals Grb2 monomer–dimer equilibrium determines normal versus oncogenic function

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Zamal Ahmed ◽  
Zahra Timsah ◽  
Kin M. Suen ◽  
Nathan P. Cook ◽  
Gilbert R. Lee ◽  
...  
Keyword(s):  
Map Kinase ◽  
Cancer Progression ◽  
Protein Interactions ◽  
Tyrosine Kinases ◽  
Growth Factor Receptor ◽  
Adaptor Protein ◽  
Sh2 Domain ◽  
Breast Cancers ◽  
Mitogen Activated Protein ◽  
Self Association

Abstract The adaptor protein growth factor receptor-bound protein 2 (Grb2) is ubiquitously expressed in eukaryotic cells and involved in a multitude of intracellular protein interactions. Grb2 plays a pivotal role in tyrosine kinase-mediated signal transduction including linking receptor tyrosine kinases to the Ras/mitogen-activated protein (MAP) kinase pathway, which is implicated in oncogenic outcome. Grb2 exists in a constitutive equilibrium between monomeric and dimeric states. Here we show that only monomeric Grb2 is capable of binding to SOS and upregulating MAP kinase signalling and that the dimeric state is inhibitory to this process. Phosphorylation of tyrosine 160 (Y160) on Grb2, or binding of a tyrosylphosphate-containing ligand to the SH2 domain of Grb2, results in dimer dissociation. Phosphorylation of Y160 on Grb2 is readily detectable in the malignant forms of human prostate, colon and breast cancers. The self-association/dissociation of Grb2 represents a switch that regulates MAP kinase activity and hence controls cancer progression.

scholarly journals The Carboxyl Terminus of v-Abl Protein Can Augment SH2 Domain Function

2000 ◽  
Vol 74 (10) ◽  
pp. 4495-4504 ◽  
Author(s):  
David Warren ◽  
Andrew J. Heilpern ◽  
Kent Berg ◽  
Naomi Rosenberg
Keyword(s):  
Map Kinase ◽  
Protein Interactions ◽  
Leukemia Virus ◽  
Sh2 Domain ◽  
Carboxyl Terminus ◽  
Abl Tyrosine Kinase ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
Nih 3T3 ◽  
Kinase Pathway

ABSTRACT Abelson murine leukemia virus (Ab-MLV) transforms NIH 3T3 and pre-B cells via expression of the v-Abl tyrosine kinase. Although the enzymatic activity of this molecule is absolutely required for transformation, other regions of the protein are also important for this response. Among these are the SH2 domain, involved in phosphotyrosine-dependent protein-protein interactions, and the long carboxyl terminus, which plays an important role in transformation of hematopoietic cells. Important signals are sent from each of these regions, and transformation is most likely orchestrated by the concerted action of these different parts of the protein. To explore this idea, we compared the ability of the v-Src SH2 domain to substitute for that of v-Abl in the full-length P120 v-Abl protein and in P70 v-Abl, a protein that lacks the carboxyl terminus characteristic of Abl family members. Ab-MLV strains expressing P70/S2 failed to transform NIH 3T3 cells and demonstrated a greatly reduced capacity to mediate signaling events associated with the Ras-dependent mitogen-activated protein (MAP) kinase pathway. In contrast, Ab-MLV strains expressing P120/S2 were indistinguishable from P120 with respect to these features. Analyses of additional mutants demonstrated that the last 162 amino acids of the carboxyl terminus were sufficient to restore transformation. These data demonstrate that an SH2 domain with v-Abl substrate specificity is required for NIH 3T3 transformation in the absence of the carboxyl terminus and suggest that cooperativity between the extreme carboxyl terminus and the SH2 domain facilitates the transmission of transforming signals via the MAP kinase pathway.

scholarly journals The intramolecular allostery of GRB2 governing its interaction with SOS1 is modulated by phosphotyrosine ligands

2021 ◽  
Author(s):  
Neda Sadat Kazemein Jasemi ◽  
Christian Herrmann ◽  
Eva Magdalena Estirado ◽  
Lothar Gremer ◽  
Dieter Willbold ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Growth Factor Receptor ◽  
Adaptor Protein ◽  
Sh2 Domain ◽  
Important Advance ◽  
Tyrosine Residues ◽  
Rich Domain ◽  
Allosteric Mechanism ◽  
Domain Interactions ◽  
Growth Factor Receptor Bound

Growth factor receptor-bound protein 2 (GRB2) is a trivalent adaptor protein and a key element in signal transduction. It interacts via its flanking nSH3 and cSH3 domains with the proline-rich domain (PRD) of the RAS activator SOS1 and via its central SH2 domain with phosphorylated tyrosine residues of receptor tyrosine kinases (RTKs; e.g., HER2). The elucidation of structural organization and mechanistic insights into GRB2 interactions, however, remain challenging due to their inherent flexibility. This study represents an important advance in our mechanistic understanding of how GRB2 links RTKs to SOS1. Accordingly, it can be proposed that (1) HER2 pYP-bound SH2 potentiates GRB2 SH3 domain interactions with SOS1 (an allosteric mechanism); (2) the SH2 domain blocks cSH3,enabling nSH3 to bind SOS1 first before cSH3 follows (an avidity-based mechanism); and (3) the allosteric behavior of cSH3 to other domains appears to be unidirectional, although there is an allosteric effect between the SH2 and SH3 domains.

Differential effect of the inhibition of Grb2–SH3 interactions in platelet activation induced by thrombin and by Fc receptor engagement

2002 ◽  
Vol 363 (3) ◽  
pp. 717-725
Author(s):  
Abdelhafid SACI ◽  
Wang-Qing LIU ◽  
Michel VIDAL ◽  
Christiane GARBAY ◽  
Francine RENDU ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Protein Interactions ◽  
Growth Factor Receptor ◽  
Adaptor Protein ◽  
Blood Platelet ◽  
Sh2 Domain ◽  
Fc Receptor ◽  
Serotonin Release ◽  
Activated Platelets

The adaptor protein Grb2 (growth factor receptor-bound protein 2) is involved in cell proliferation via the Ras signalling pathway. In order to study the role of Grb2 in blood platelet responses, we used a peptide containing two proline-rich sequences derived from Sos (peptidimer), which binds to Grb2—Src homology 3 domain (SH3) with a high affinity, and hence inhibits Grb2—SH3-mediated protein interactions. Platelet aggregation and 5-hydroxytryptamine (serotonin) release measured in the presence of the peptidimer were: (i) significantly decreased when induced by thrombin; and (ii) potentiated when induced by the engagement of the Fc receptor. In thrombin-activated platelets, the Grb2—SH2 domain formed an association with the β3 subunit of the αIIb—β3 integrin (GPIIb—IIIa), Shc, Syk, Src and SHP1 (SH2-containing phosphotyrosine phosphatase 1), whereas these associations did not occur after the engagement of the receptor for the Fc domain of IgG (FcγRIIa) or in resting platelets. Grb2—SH3 domains formed an association with the proline-rich sequences of Sos and Cbl in both resting and activated platelets, since the peptidimer abolished these associations. Inhibition of both fibrinogen binding and platelet aggregation by the peptide RGDS (Arg-Gly-Asp-Ser) had no effect on thrombin-induced Grb2—SH2 domain association with the aforementioned signalling molecules, indicating that these associations occurred during thrombin-induced ‘inside-out’ signalling. Platelet aggregation induced by direct activation via αIIb—β3 ('outside-in’ signalling) was potentiated by the peptidimer. The results show that inhibition of Grb2—SH3 interactions with signal-transduction proteins down-regulates thrombin-induced platelet activation, but also potentiates Fc receptor- and αIIb—β3-mediated platelet activation.

scholarly journals Dominant Mutations of Drosophila MAP Kinase Kinase and Their Activities in Drosophila and Yeast MAP Kinase Cascades

Genetics ◽  
1997 ◽  
Vol 146 (1) ◽  
pp. 263-273 ◽  
Author(s):  
Young-Mi Lim ◽  
Leo Tsuda ◽  
Yoshihiro H Inoue ◽  
Kenji Irie ◽  
Takashi Adachi-Yamada ◽  
...  
Keyword(s):  
Map Kinase ◽  
Tyrosine Kinases ◽  
Egf Receptor ◽  
Kinase Domain ◽  
Nucleotide Sequencing ◽  
Gain Of Function ◽  
Highly Sensitive ◽  
Mitogen Activated Protein ◽  
Signal Specificity ◽  
Map Kinase Kinase

Eight alleles of Dsor1 encoding a Drosophila homologue of mitogen-activated protein (MAP) kinase kinase were obtained as dominant suppressors of the MAP kinase kinase kinase D-raf. These Dsor1 alleles themselves showed no obvious phenotypic consequences nor any effect on the viability of the flies, although they were highly sensitive to upstream signals and strongly interacted with gain-of-function mutations of upstream factors. They suppressed mutations for receptor tyrosine kinases (RTKs); torso (tor), sevenless (sev) and to a lesser extent Drosophila EGF receptor (DER). Furthermore, the Dsor1 alleles showed no significant interaction with gain-of-function mutations of DER. The observed difference in activity of the Dsor1 alleles among the RTK pathways suggests Dsor1 is one of the components of the pathway that regulates signal specificity. Expression of Dsor1 in budding yeast demonstrated that Dsor1 can activate yeast MAP kinase homologues if a proper activator of Dsor1 is coexpressed. Nucleotide sequencing of the Dsor1 mutant genes revealed that most of the mutations are associated with amino acid changes at highly conserved residues in the kinase domain. The results suggest that they function as suppressors due to increased reactivity to upstream factors.

scholarly journals Integrins can collaborate with growth factors for phosphorylation of receptor tyrosine kinases and MAP kinase activation: roles of integrin aggregation and occupancy of receptors.

1996 ◽  
Vol 135 (6) ◽  
pp. 1633-1642 ◽  
Author(s):  
S Miyamoto ◽  
H Teramoto ◽  
J S Gutkind ◽  
K M Yamada
Keyword(s):  
Signal Transduction ◽  
Growth Factors ◽  
Growth Factor ◽  
Map Kinase ◽  
Tyrosine Kinases ◽  
Map Kinases ◽  
Egf Receptor ◽  
Growth Factor Receptor ◽  
Kinase Activation ◽  
Transient Activation

Integrins mediate cell adhesion, migration, and a variety of signal transduction events. These integrin actions can overlap or even synergize with those of growth factors. We examined for mechanisms of collaboration or synergy between integrins and growth factors involving MAP kinases, which regulate many cellular functions. In cooperation with integrins, the growth factors EGF, PDGF-BB, and basic FGF each produced a marked, transient activation of the ERK (extracellular signal-regulated kinase) class of MAP kinase, but only if the integrins were both aggregated and occupied by ligand. Transmembrane accumulation of total tyrosine-phosphorylated proteins, as well as nonsynergistic MAP kinase activation, could be induced by simple integrin aggregation, whereas enhanced transient accumulation of the EGF-receptor substrate eps8 required integrin aggregation and occupancy, as well as EGF treatment. Each type of growth factor receptor was itself induced to aggregate transiently by integrin ligand-coated beads in a process requiring both aggregation and occupancy of integrin receptors, but not the presence of growth factor ligand. Synergism was also observed between integrins and growth factors for triggering tyrosine phosphorylation of EGF, PDGF, and FGF receptors. This collaborative response also required both integrin aggregation and occupancy. These studies identify mechanisms in the signal transduction response to integrins and growth factors that require various combinations of integrin aggregation and ligands for integrin or growth factor receptors, providing opportunities for collaboration between these major regulatory systems.

Functional Role of p38 Mitogen Activated Protein Kinase in Platelet Activation induced by a Thromboxane A2 Analogue and by 8-iso-prostaglandin F2 α

2002 ◽  
Vol 87 (05) ◽  
pp. 888-898 ◽  
Author(s):  
Stefania Gaino ◽  
Valeria Zuliani ◽  
Rosa Tommasoli ◽  
Donatella Benati ◽  
Riccardo Ortolani ◽  
...  
Keyword(s):  
Map Kinase ◽  
Platelet Activation ◽  
Tyrosine Kinases ◽  
Actin Polymerization ◽  
Shape Change ◽  
Specific Inhibitor ◽  
P38 Map Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Kinase Phosphorylation

SummaryWe investigated similarities in the signaling pathways elicited by the F2 isoprostane 8-iso-PGF2α and by low doses of U46619 to induce platelet activation. Both 0.01-0.1 µmol/L U46619 and 0.01-1 µmol/L 8-isoPGF2α triggered shape change and filopodia extension, as well as adhesion to immobilized fibrinogen of washed platelets. At these doses the two platelet agonists failed to trigger secretion and aggregation, which were however induced by higher doses of U46619 (0.1-1 µmol/L). SB203580 (1-10 µmol/L), a specific inhibitor of the p38 mitogen activated protein (MAP) kinase blunted platelet shape change and adhesion induced by 0.05-1 µmol/L 8-iso-PGF2α and by 0.01 µmol/L U46619. These platelet responses were also inhibited by 20 µmol/L cytochalasin D, an inhibitor of actin polymerization, and 50 µmol/L piceatannol, an inhibitor of the Syk tyrosine kinases. Both 8-iso-PGF2α and U46619-induced p38 MAP kinase phosphorylation in suspended platelets and this was inhibited by piceatannol, indicating that Syk activation occurs upstream p38 MAP kinase phosphorylation. These findings suggest that the signaling pathway triggered by both 8-iso-PGF2α and low concentrations of U46619 to induce platelet adhesion and shape change implicates Syk, the p38 MAP kinase, and actin polymerization.

scholarly journals The Shb scaffold binds the Nck adaptor protein, p120 RasGAP, and Chimaerins and thereby facilitates heterotypic cell segregation by the receptor EphB2

2020 ◽  
Vol 295 (12) ◽  
pp. 3932-3944 ◽  
Author(s):  
Melany J. Wagner ◽  
Marilyn S. Hsiung ◽  
Gerald D. Gish ◽  
Rick D. Bagshaw ◽  
Sasha A. Doodnauth ◽  
...  
Keyword(s):  
Tyrosine Kinases ◽  
Cell Movement ◽  
Adaptor Protein ◽  
Receptor Activation ◽  
Sh2 Domain ◽  
Tumor Formation ◽  
Eph Receptors ◽  
Eph Receptor ◽  
Varied Composition ◽  
Cell Segregation

Eph receptors are a family of receptor tyrosine kinases that control directional cell movement during various biological processes, including embryogenesis, neuronal pathfinding, and tumor formation. The biochemical pathways of Eph receptors are context-dependent in part because of the varied composition of a heterotypic, oligomeric, active Eph receptor complex. Downstream of the Eph receptors, little is known about the essential phosphorylation events that define the context and instruct cell movement. Here, we define a pathway that is required for Eph receptor B2 (EphB2)–mediated cell sorting and is conserved among multiple Eph receptors. Utilizing a HEK293 model of EphB2+/ephrinB1+ cell segregation, we found that the scaffold adaptor protein SH2 domain–containing adaptor protein B (Shb) is essential for EphB2 functionality. Further characterization revealed that Shb interacts with known modulators of cytoskeletal rearrangement and cell mobility, including Nck adaptor protein (Nck), p120-Ras GTPase-activating protein (RasGAP), and the α- and β-Chimaerin Rac GAPs. We noted that phosphorylation of Tyr297, Tyr246, and Tyr336 of Shb is required for EphB2–ephrinB1 boundary formation, as well as binding of Nck, RasGAP, and the chimaerins, respectively. Similar complexes were formed in the context of EphA4, EphA8, EphB2, and EphB4 receptor activation. These results indicate that phosphotyrosine-mediated signaling through Shb is essential in EphB2-mediated heterotypic cell segregation and suggest a conserved function for Shb downstream of multiple Eph receptors.

Human SLP-65 isoforms contribute differently to activation and apoptosis of B lymphocytes

Blood ◽  
2006 ◽  
Vol 108 (12) ◽  
pp. 3761-3768 ◽  
Author(s):  
Annika Grabbe ◽  
Jürgen Wienands
Keyword(s):  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Adaptor Protein ◽  
Sh2 Domain ◽  
Binding Motif ◽  
B Lymphopoiesis ◽  
Suppressor Activity ◽  
B Cell Signaling ◽  
Tumor Suppressor Activity ◽  
Mitogen Activated Protein

AbstractThe SH2 domain-containing leukocyte adaptor protein of 65 kDa (SLP-65) is the key effector for signaling downstream of the B-cell antigen receptor (BCR). SLP-65 controls not only B lymphopoiesis and humoral immunity but also possesses a yet poorly defined tumor suppressor activity that is lost in many cases of acute lymphoblastic leukemia. We found that the 2 isoforms of human SLP-65 are differentially involved in positive and negative B-cell signaling. Reconstitution experiments revealed that an atypical SH3 domain-binding motif, which is present in the long but not in the short SLP-65 isoform, mediates association to Grb2 and suppresses activation of mitogen-activated protein kinases p38 and JNK as well as up-regulation of c-Fos expression. In turn, the short isoform activates not only AP1-driven but also NF-κB–driven gene transcription more potently than the long isoform. Conversely, the long rather than the short SLP-65 isoform promotes BCR-induced B-cell apoptosis. Our data further delineate the structural requirements of positive and negative SLP-65 signal transduction in normal and neoplastic cells.

scholarly journals Mitogen-activated protein kinase activation is insufficient for growth factor receptor-mediated PC12 cell differentiation.

1995 ◽  
Vol 15 (7) ◽  
pp. 3644-3653 ◽  
Author(s):  
R R Vaillancourt ◽  
L E Heasley ◽  
J Zamarripa ◽  
B Storey ◽  
M Valius ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Growth Factor ◽  
Map Kinase ◽  
Pc12 Cells ◽  
Pc12 Cell ◽  
Growth Factor Receptor ◽  
Receptor Activation ◽  
Mitogen Activated Protein ◽  
Map Kinase Pathway ◽  
Kinase Pathway

When expressed in PC12 cells, the platelet-derived growth factor beta receptor (beta PDGF-R) mediates cell differentiation. Mutational analysis of the beta PDGF-R indicated that persistent receptor stimulation of the Ras/Raf/mitogen-activated protein (MAP) kinase pathway alone was insufficient to sustain PC12 cell differentiation. PDGF receptor activation of signal pathways involving p60c-src or the persistent regulation of phospholipase C gamma was required for PC12 cell differentiation. beta PDGF-R regulation of phosphatidylinositol 3-kinase, the GTPase-activating protein of Ras, and the tyrosine phosphatase, Syp, was not required for PC12 cell differentiation. In contrast to overexpression of oncoproteins involved in regulating the MAP kinase pathway, growth factor receptor-mediated differentiation of PC12 cells requires the integration of other signals with the Ras/Raf/MAP kinase pathway.

scholarly journals Grb2 controls phosphorylation of FGFR2 by inhibiting receptor kinase and Shp2 phosphatase activity

2013 ◽  
Vol 200 (4) ◽  
pp. 493-504 ◽  
Author(s):  
Zamal Ahmed ◽  
Chi-Chuan Lin ◽  
Kin M. Suen ◽  
Fernando A. Melo ◽  
James A Levitt ◽  
...  
Keyword(s):  
Growth Factor ◽  
Phosphatase Activity ◽  
Tyrosine Phosphatase ◽  
Growth Factor Receptor ◽  
Adaptor Protein ◽  
Sh2 Domain ◽  
Receptor Kinase ◽  
Downstream Signaling ◽  
State Growth ◽  
Kinase Phosphorylation

Constitutive receptor tyrosine kinase phosphorylation requires regulation of kinase and phosphatase activity to prevent aberrant signal transduction. A dynamic mechanism is described here in which the adaptor protein, growth factor receptor–bound protein 2 (Grb2), controls fibroblast growth factor receptor 2 (FGFR2) signaling by regulating receptor kinase and SH2 domain–containing protein tyrosine phosphatase 2 (Shp2) phosphatase activity in the absence of extracellular stimulation. FGFR2 cycles between its kinase-active, partially phosphorylated, nonsignaling state and its Shp2-dephosphorylated state. Concurrently, Shp2 cycles between its FGFR2-phosphorylated and dephosphorylated forms. Both reciprocal activities of FGFR2 and Shp2 were inhibited by binding of Grb2 to the receptor. Phosphorylation of Grb2 by FGFR2 abrogated its binding to the receptor, resulting in up-regulation of both FGFR2’s kinase and Shp2’s phosphatase activity. Dephosphorylation of Grb2 by Shp2 rescued the FGFR2–Grb2 complex. This cycling of enzymatic activity results in a homeostatic, signaling-incompetent state. Growth factor binding perturbs this background cycling, promoting increased FGFR2 phosphorylation and kinase activity, Grb2 dissociation, and downstream signaling. Grb2 therefore exerts constitutive control over the mutually dependent activities of FGFR2 and Shp2.

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