The Experts below are selected from a list of 19992 Experts worldwide ranked by ideXlab platform
Susan O Meakin - One of the best experts on this subject based on the ideXlab platform.
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The Signaling Adapter, FRS2, Facilitates Neuronal Branching in Primary Cortical Neurons via Both Grb2- and Shp2-Dependent Mechanisms
Journal of molecular neuroscience : MN, 2014Co-Authors: Li Zhou, Asghar Talebian, Susan O MeakinAbstract:The neurotrophins are a family of closely related growth factors that regulate proliferation and differentiation in the developing and mature nervous systems. Neurotrophins stimulate a family of receptor tyrosine kinases (Trk receptors) and utilize an intracellular docking protein termed fibroblast growth factor (FGF) receptor substrate 2 (FRS2) as a major downstream adapter to activate Ras, phosphatidylinositide 3-kinase (PI3K), and mitogen-activated protein kinase (MAPK) signaling cascades. The goals of this study were twofold: first, to investigate the complexity of neurotrophin-induced FRS2 interactions in primary cortical neurons and to determine which pathway(s) are important in regulating neuronal growth and, second, to determine whether the related signaling adapter, FRS3, stimulates neuron growth comparable to FRS2. We find that neurotrophin treatment of primary cortical neurons stimulates the tyrosine phosphorylation of FRS2 and the subsequent recruitment of Shp2, Grb2, and Gab2. With FRS2 mutants deficient in Grb2 or Shp2 binding, we demonstrate that FRS2 binds Gab1 and Gab2 through Grb2, providing an alternative route to activate PI3 kinase and Shp2. Using recombinant adenoviruses expressing FRS2, we demonstrate that FRS2 overexpression promotes neurite outgrowth and branching in cortical neurons relative to controls. In contrast, overexpression of FRS3 does not stimulate neuronal growth. Moreover, we find that while loss of Shp2, but not Grb2, reduces brain-derived neurotrophic factor (BDNF)-induced MAPK activation, the loss of either pathway impairs neuronal growth. Collectively, these experiments demonstrate that FRS2 functions as an adapter of a multiprotein complex that is activated by the Trk receptors and that the activation of both Grb2- and Shp2-dependent pathways facilitates cortical neuronal growth.
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Role and expression of FRS2 and FRS3 in prostate cancer
BMC cancer, 2011Co-Authors: Tania Valencia, Susan O Meakin, Ajay Joseph, Naveen Kachroo, Steve Darby, Vincent J. GnanapragasamAbstract:Background FGF receptor substrates (FRS2 and FRS3) are key adaptor proteins that mediate FGF-FGFR signalling in benign as well as malignant tissue. Here we investigated FRS2 and FRS3 as a means of disrupting global FGF signalling in prostate cancer.
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The fibroblast growth factor receptor substrate 3 adapter is a developmentally regulated microtubule-associated protein expressed in migrating and differentiated neurons
Journal of neurochemistry, 2009Co-Authors: Todd Hryciw, James I S Macdonald, Renée Phillips, Claudia Seah, Stephen H. Pasternak, Susan O MeakinAbstract:J. Neurochem. (2009) 112, 924–939. Abstract Fibroblast growth factor (FGF) mediated signaling is essential to many aspects of neural development. Activated FGF receptors signal primarily through the FGF receptor substrate (Frs) adapters, which include FRS2/FRS2α and Frs3/FRS2β. While some studies suggest that Frs3 can compensate for the loss of FRS2 in transfected cells, the lack of an effective Frs3 specific antibody has prevented efforts to determine the role(s) of the endogenous protein. To this end, we have generated a Frs3 specific antibody and have characterized the pattern of Frs3 expression in the developing nervous system, its subcellular localization as well as its biochemical properties. We demonstrate that Frs3 is expressed at low levels in the ventricular zone of developing cortex, between E12 and E15, and it co-localizes with nestin and acetylated α-tubulin in radial processes in the ventricular/subventricular zones as well as with βIII tubulin in differentiated cortical neurons. Subcellular fractionation studies demonstrate that endogenous Frs3 is both soluble and plasma membrane associated while Frs3 expressed in 293T cells associates exclusively with lipid rafts. Lastly, we demonstrate that neuronal Frs3 binds microtubules comparable to the microtubule-associated protein, MAP2, while FRS2 does not. Collectively, these data suggest that neuronal Frs3 functions as a novel microtubule binding protein and they provide the first biochemical evidence that neuronal Frs3 is functionally distinct from FRS2/FRS2α.
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trk receptor binding and neurotrophin fibroblast growth factor fgf dependent activation of the fgf receptor substrate frs 3
Biochimica et Biophysica Acta, 2006Co-Authors: Scott J Dixon, James I S Macdonald, Susan O Meakin, Kim N Robinson, Christopher J KubuAbstract:Abstract We have investigated the signaling properties of the fibroblast growth factor (FGF) receptor substrate 3 (FRS3), also known as SNT-2 or FRS2β, in neurotrophin-dependent differentiation in comparison with the related adapter FRS2 (SNT1 or FRS2α). We demonstrate that FRS3 binds all neurotrophin Trk receptor tyrosine kinases and becomes tyrosine phosphorylated in response to NGF, BDNF, NT-3 and FGF stimulation in transfected cells and/or primary cortical neurons. Second, the signaling molecules Grb2 and Shp2 bind FRS3 at consensus sites that are highly conserved among FRS family members and that Shp2, in turn, becomes tyrosine phosphorylated. While FRS3 over-expression in PC12 cells neither increases NGF-induced neuritogenesis nor activation of Map kinase/AKT, comparable to previous reports on FRS2, over-expression of a chimeric adapter containing the PH/PTB domains of the insulin receptor substrate (IRS) 2, in place of the PTB domain of FRS3 (IRS2-FRS3) supports insulin-dependent Map kinase activation and neurite outgrowth in PC12 cells. Collectively, these data demonstrate that FRS3 supports ligand-induced Map kinase activation and that the chimeric IRS2-FRS3 adapter is stimulating sufficient levels of activated MapK to support neurite outgrowth in PC12 cells.
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trk receptor binding and neurotrophin fibroblast growth factor fgf dependent activation of the fgf receptor substrate frs 3
Biochimica et Biophysica Acta, 2006Co-Authors: Scott J Dixon, James I S Macdonald, Susan O Meakin, Kim N Robinson, Christopher J KubuAbstract:We have investigated the signaling properties of the fibroblast growth factor (FGF) receptor substrate 3 (FRS3), also known as SNT-2 or FRS2beta, in neurotrophin-dependent differentiation in comparison with the related adapter FRS2 (SNT1 or FRS2alpha). We demonstrate that FRS3 binds all neurotrophin Trk receptor tyrosine kinases and becomes tyrosine phosphorylated in response to NGF, BDNF, NT-3 and FGF stimulation in transfected cells and/or primary cortical neurons. Second, the signaling molecules Grb2 and Shp2 bind FRS3 at consensus sites that are highly conserved among FRS family members and that Shp2, in turn, becomes tyrosine phosphorylated. While FRS3 over-expression in PC12 cells neither increases NGF-induced neuritogenesis nor activation of Map kinase/AKT, comparable to previous reports on FRS2, over-expression of a chimeric adapter containing the PH/PTB domains of the insulin receptor substrate (IRS) 2, in place of the PTB domain of FRS3 (IRS2-FRS3) supports insulin-dependent Map kinase activation and neurite outgrowth in PC12 cells. Collectively, these data demonstrate that FRS3 supports ligand-induced Map kinase activation and that the chimeric IRS2-FRS3 adapter is stimulating sufficient levels of activated MapK to support neurite outgrowth in PC12 cells.
Joseph Schlessinger - One of the best experts on this subject based on the ideXlab platform.
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FRS2 family docking proteins with overlapping roles in activation of MAP kinase have distinct spatial-temporal patterns of expression of their transcripts.
FEBS letters, 2004Co-Authors: Noriko Gotoh, Irit Lax, Shaked Laks, Misako Nakashima, Joseph SchlessingerAbstract:FRS2alpha and FRS2beta, two members of the FRS2 family of docking proteins, become tyrosine phosphorylated in response to fibroblast growth factor (FGF) or nerve growth factor (NGF) stimulation. Tyrosine phosphorylated FRS2alpha serves as a platform for the recruitment of multiple signaling proteins for activation of the Ras-mitogen-activated protein (MAP) kinase signaling cascade. We report that FRS2alpha and FRS2beta have distinct spatio-temporal expression patterns in mouse embryos. We further show that FRS2beta can compensate for the loss of FRS2alpha for activation of MAP kinase when expressed in fibroblasts from FRS2alpha(-/-) mouse embryos. We propose that the FRS2 family proteins have distinct roles in vivo through activation of common signaling proteins including MAP kinase.
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FRS2 family docking proteins with overlapping roles in activation of MAP kinase have distinct spatial-temporal patterns of expression of their transcripts.
FEBS Letters, 2004Co-Authors: Noriko Gotoh, Irit Lax, Shaked Laks, Misako Nakashima, Joseph SchlessingerAbstract:Abstract FRS2α and FRS2β, two members of the FRS2 family of docking proteins, become tyrosine phosphorylated in response to fibroblast growth factor (FGF) or nerve growth factor (NGF) stimulation. Tyrosine phosphorylated FRS2α serves as a platform for the recruitment of multiple signaling proteins for activation of the Ras-mitogen-activated protein (MAP) kinase signaling cascade. We report that FRS2α and FRS2β have distinct spatio-temporal expression patterns in mouse embryos. We further show that FRS2β can compensate for the loss of FRS2α for activation of MAP kinase when expressed in fibroblasts from FRS2α−/− mouse embryos. We propose that the FRS2 family proteins have distinct roles in vivo through activation of common signaling proteins including MAP kinase.
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docking protein FRS2 links the protein tyrosine kinase ret and its oncogenic forms with the mitogen activated protein kinase signaling cascade
Molecular and Cellular Biology, 2001Co-Authors: Rosa Marina Melillo, Y. R. Hadari, M Santoro, Marc Billaud, Alfredo Fusco, Joseph SchlessingerAbstract:The receptor tyrosine kinase RET functions as the signal transducing receptor for the GDNF (for “glial cell-derived neurotrophic factors”) family of ligands. Mutations in the RET gene were implicated in Hirschsprung disease (HSCR), multiple endocrine neoplasia type 2 (MEN 2), and thyroid carcinomas. In this report we demonstrate that the docking protein FRS2 is tyrosine phosphorylated by ligand-stimulated and by constitutively activated oncogenic forms of RET. Complex formation between RET and FRS2 is mediated by binding of the phosphotyrosine-binding domain of FRS2 to pY1062, a residue in RET that also functions as a binding site for Shc. However, overexpression of FRS2 but not Shc potentiates mitogen-activated protein (MAP) kinase activation by RET oncoproteins. We demonstrate that oncogenic RET-PTC proteins are associated with FRS2 constitutively, leading to tyrosine phosphorylation of FRS2, MAP kinase stimulation, and cell proliferation. However, loss-of-function HSCR-associated RET mutants exhibit impaired FRS2 binding and reduced MAP kinase activation. These experiments demonstrate that FRS2 couples both ligand-regulated and oncogenic forms of RET, with the MAP kinase signaling cascade as part of the response of RET under normal biological conditions and pathological conditions, such as MEN 2 and papillary thyroid carcinomas.
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Stimulation of phosphatidylinositol 3-kinase by fibroblast growth factor receptors is mediated by coordinated recruitment of multiple docking proteins.
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: S. H. Ong, Noriko Gotoh, Joseph Schlessinger, Y. R. Hadari, G. R. Guy, Irit LaxAbstract:The docking protein FRS2 is a major downstream effector that links fibroblast growth factor (FGF) and nerve growth factor receptors with the Ras/mitogen-activated protein kinase signaling cascade. In this report, we demonstrate that FRS2 also plays a pivotal role in FGF-induced recruitment and activation of phosphatidylinositol 3-kinase (PI3-kinase). We demonstrate that tyrosine phosphorylation of FRS2α leads to Grb2-mediated complex formation with the docking protein Gab1 and its tyrosine phosphorylation, resulting in the recruitment and activation of PI3-kinase. Furthermore, Grb2 bound to tyrosine-phosphorylated FRS2 through its SH2 domain interacts primarily via its carboxyl-terminal SH3 domain with a proline-rich region in Gab1 and via its amino-terminal SH3 domain with the nucleotide exchange factor Sos1. Assembly of FRS2α:Grb2:Gab1 complex induced by FGF stimulation results in activation of PI3-kinase and downstream effector proteins such as the S/T kinase Akt, whose cellular localization and activity are regulated by products of PI3-kinase. These experiments reveal a unique mechanism for generation of signal diversity by growth factor-induced coordinated assembly of a multidocking protein complex that can activate the Ras/mitogen-activated protein kinase cascade to induce cell proliferation and differentiation, and PI3-kinase to activate a mediator of a cell survival pathway.
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FRS2 proteins recruit intracellular signaling pathways by binding to diverse targets on fibroblast growth factor and nerve growth factor receptors.
Molecular and cellular biology, 2000Co-Authors: S. H. Ong, Noriko Gotoh, Joseph Schlessinger, Y. R. Hadari, G. R. Guy, Shaked Laks, Irit LaxAbstract:The docking protein FRS2 was implicated in the transmission of extracellular signals from the fibroblast growth factor (FGF) or nerve growth factor (NGF) receptors to the Ras/mitogen-activated protein kinase signaling cascade. The two members of the FRS2 family, FRS2α and FRS2β, are structurally very similar. Each is composed of an N-terminal myristylation signal, a phosphotyrosine-binding (PTB) domain, and a C-terminal tail containing multiple binding sites for the SH2 domains of the adapter protein Grb2 and the protein tyrosine phosphatase Shp2. Here we show that the PTB domains of both the α and β isoforms of FRS2 bind directly to the FGF or NGF receptors. The PTB domains of the FRS2 proteins bind to a highly conserved sequence in the juxtamembrane region of FGFR1. While FGFR1 interacts with FRS2 constitutively, independent of ligand stimulation and tyrosine phosphorylation, NGF receptor (TrkA) binding to FRS2 is strongly dependent on receptor activation. Complex formation with TrkA is dependent on phosphorylation of Y490, a canonical PTB domain binding site that also functions as a binding site for Shc (NPXpY). Using deletion and alanine scanning mutagenesis as well as peptide competition assays, we demonstrate that the PTB domains of the FRS2 proteins specifically recognize two different primary structures in two different receptors in a phosphorylation-dependent or -independent manner. In addition, NGF-induced tyrosine phosphorylation of FRS2α is diminished in cells that overexpress a kinase-inactive mutant of FGFR1. This experiment suggests that FGFR1 may regulate signaling via NGF receptors by sequestering a common key element which both receptors utilize for transmitting their signals. The multiple interactions mediated by FRS2 appear to play an important role in target selection and in defining the specificity of several families of receptor tyrosine kinases.
Noriko Gotoh - One of the best experts on this subject based on the ideXlab platform.
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adaptor protein complex of FRS2β and cin85 cd2ap provides a novel mechanism for erbb2 her2 protein downregulation
Cancer Science, 2013Co-Authors: Yuriko Minegishi, Anna Mizutani, Tohru Tezuka, Yoshio Shibagaki, Masahiko Kuroda, Seisuke Hattori, Masao Kinoshita, Koji Fujita, Noriko GotohAbstract:Overexpression of the ErbB2/HER2 receptor tyrosine kinase contributes to tumorigenesis. However, mechanisms regulating ErbB2 protein levels remain largely unclear. Here, we identified novel mechanisms of ErbB2 downregulation. ErbB2 constitutively binds to an adaptor protein FRS2β. We found that FRS2β bound to CD2AP and CIN85, which induces endosomal trafficking that targets lysosomes. FRS2β colocalized with CIN85 in the cytoplasm. Expression of wild type FRS2β but not its CIN85 non-binding mutant, downregulated the ErbB2 protein and inhibited anchorage-independent cell growth. Moreover, the E3 ubiquitin-protein ligase Cbl was contained within a complex of FRS2β and CIN85. Knockdown of both CIN85 and CD2AP or of Cbl, or treatment with lysosomal degradation inhibitors diminished FRS2β downregulation of ErbB2. In addition, knockdown of endogenous FRS2β caused upregulation of ErbB2 in primary neural cells. Finally, immunohistochemical analysis showed that human breast cancer tissues that overexpress ErbB2 expressed low levels of FRS2β. Thus, an FRS2β-CIN85/CD2AP-Cbl axis for downregulation of ErbB2 may regulate ErbB2 protein levels in physiological and pathological settings. Molecular targeting drugs that can increase or stabilize the ErbB2-FRS2β-CIN85/CD2AP-Cbl axis may have promise for the control of ErbB2-overexpressing tumors.
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Adaptor protein complex of FRS2β and CIN85/CD2AP provides a novel mechanism for ErbB2/HER2 protein downregulation.
Cancer Science, 2013Co-Authors: Yuriko Minegishi, Anna Mizutani, Tohru Tezuka, Yoshio Shibagaki, Masahiko Kuroda, Seisuke Hattori, Masao Kinoshita, Koji Fujita, Noriko GotohAbstract:Overexpression of the ErbB2/HER2 receptor tyrosine kinase contributes to tumorigenesis. However, mechanisms regulating ErbB2 protein levels remain largely unclear. Here, we identified novel mechanisms of ErbB2 downregulation. ErbB2 constitutively binds to an adaptor protein FRS2β. We found that FRS2β bound to CD2AP and CIN85, which induces endosomal trafficking that targets lysosomes. FRS2β colocalized with CIN85 in the cytoplasm. Expression of wild type FRS2β but not its CIN85 non-binding mutant, downregulated the ErbB2 protein and inhibited anchorage-independent cell growth. Moreover, the E3 ubiquitin-protein ligase Cbl was contained within a complex of FRS2β and CIN85. Knockdown of both CIN85 and CD2AP or of Cbl, or treatment with lysosomal degradation inhibitors diminished FRS2β downregulation of ErbB2. In addition, knockdown of endogenous FRS2β caused upregulation of ErbB2 in primary neural cells. Finally, immunohistochemical analysis showed that human breast cancer tissues that overexpress ErbB2 expressed low levels of FRS2β. Thus, an FRS2β-CIN85/CD2AP-Cbl axis for downregulation of ErbB2 may regulate ErbB2 protein levels in physiological and pathological settings. Molecular targeting drugs that can increase or stabilize the ErbB2-FRS2β-CIN85/CD2AP-Cbl axis may have promise for the control of ErbB2-overexpressing tumors.
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The FRS2 family of docking/scaffolding adaptor proteins as therapeutic targets of cancer treatment.
Expert opinion on therapeutic targets, 2009Co-Authors: Takuya Sato, Noriko GotohAbstract:Background: There are two members – FRS2α and FRS2β – in the fibroblast growth factor receptor substrate 2 (FRS2) family of docking/scaffolding adaptor proteins. These proteins function downstream of certain kinds of receptor tyrosine kinases (RTKs) that are important for tumorigenesis. FRS2α acts as a control centre for fibroblast growth factor receptor signalling and encourages tumorigenesis, while FRS2β regulates EGFR signalling negatively, and might have a tumour suppressive role. Therefore, both proteins could be good therapeutic targets for the treatment of cancer. Objective: To examine the physiological and pathological roles of FRS2, especially in cancer, and describe their potential value as therapeutic targets. Methods: A review of relevant literature. Results/conclusions: Although it is still difficult to develop small compounds to modify functions of FRS2 adaptor proteins, such compounds may be useful as the next generation of molecular targeting drugs. Combination therapy with RTK-targeting d...
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the FRS2 family of docking scaffolding adaptor proteins as therapeutic targets of cancer treatment
Expert Opinion on Therapeutic Targets, 2009Co-Authors: Takuya Sato, Noriko GotohAbstract:Background: There are two members – FRS2α and FRS2β – in the fibroblast growth factor receptor substrate 2 (FRS2) family of docking/scaffolding adaptor proteins. These proteins function downstream of certain kinds of receptor tyrosine kinases (RTKs) that are important for tumorigenesis. FRS2α acts as a control centre for fibroblast growth factor receptor signalling and encourages tumorigenesis, while FRS2β regulates EGFR signalling negatively, and might have a tumour suppressive role. Therefore, both proteins could be good therapeutic targets for the treatment of cancer. Objective: To examine the physiological and pathological roles of FRS2, especially in cancer, and describe their potential value as therapeutic targets. Methods: A review of relevant literature. Results/conclusions: Although it is still difficult to develop small compounds to modify functions of FRS2 adaptor proteins, such compounds may be useful as the next generation of molecular targeting drugs. Combination therapy with RTK-targeting d...
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regulation of growth factor signaling by FRS2 family docking scaffold adaptor proteins
Cancer Science, 2008Co-Authors: Noriko GotohAbstract:The FRS2 family of adaptor/scaffold proteins has two members, FRS2alpha and FRS2beta. Both proteins contain N-terminal myristylation sites for localization on the plasma membrane and a PTB domain for binding to limited species of receptor tyrosine kinases (RTKs), including the FGF receptor, the neurotophin receptor, RET, and ALK. Activation of these RTKs allows FRS2 proteins to become phosphorylated of tyrosine residues and then bind to Grb2 and Shp2, a SH2 domain-containing adaptor and a tyrosine phosphatase, respectively. Subsequently, Shp2 activates a Ras/ERK pathway and Grb2 activates a Ras/ERK, phosphatidyl inositol (PI)-3 kinase and ubiquitination/degradation pathways by binding to SOS, Gab1, and Cbl via the SH3 domains of Grb2. FRS2alpha acts as 'a conning center' in FGF signaling mainly because it induces sustained levels of activation of ERK via Shp2-binding sites and Grb2-binding sites, though the contribution of the former is greater. Indeed, FRS2alpha knockout mice and mice with mutated Shp2-binding sites exhibit a variety of phenotypes due to defects in FGF signaling in vivo. Although FRS2beta binds to the EGF receptor, it does not induce tyrosine phosphorylation on the receptor. Instead, it inhibits EGF signaling, resulting in inhibition of EGF-induced cell proliferation and cell transformation. Based on these findings, the involvement of FRS2 proteins in tumorigenesis should be studied extensively to be validated as candidate biomarkers for the effectiveness of treatments targeting RTKs such as the FGF receptor and EGF receptor.
Irit Lax - One of the best experts on this subject based on the ideXlab platform.
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FRS2 family docking proteins with overlapping roles in activation of MAP kinase have distinct spatial-temporal patterns of expression of their transcripts.
FEBS Letters, 2004Co-Authors: Noriko Gotoh, Irit Lax, Shaked Laks, Misako Nakashima, Joseph SchlessingerAbstract:Abstract FRS2α and FRS2β, two members of the FRS2 family of docking proteins, become tyrosine phosphorylated in response to fibroblast growth factor (FGF) or nerve growth factor (NGF) stimulation. Tyrosine phosphorylated FRS2α serves as a platform for the recruitment of multiple signaling proteins for activation of the Ras-mitogen-activated protein (MAP) kinase signaling cascade. We report that FRS2α and FRS2β have distinct spatio-temporal expression patterns in mouse embryos. We further show that FRS2β can compensate for the loss of FRS2α for activation of MAP kinase when expressed in fibroblasts from FRS2α−/− mouse embryos. We propose that the FRS2 family proteins have distinct roles in vivo through activation of common signaling proteins including MAP kinase.
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FRS2 family docking proteins with overlapping roles in activation of MAP kinase have distinct spatial-temporal patterns of expression of their transcripts.
FEBS letters, 2004Co-Authors: Noriko Gotoh, Irit Lax, Shaked Laks, Misako Nakashima, Joseph SchlessingerAbstract:FRS2alpha and FRS2beta, two members of the FRS2 family of docking proteins, become tyrosine phosphorylated in response to fibroblast growth factor (FGF) or nerve growth factor (NGF) stimulation. Tyrosine phosphorylated FRS2alpha serves as a platform for the recruitment of multiple signaling proteins for activation of the Ras-mitogen-activated protein (MAP) kinase signaling cascade. We report that FRS2alpha and FRS2beta have distinct spatio-temporal expression patterns in mouse embryos. We further show that FRS2beta can compensate for the loss of FRS2alpha for activation of MAP kinase when expressed in fibroblasts from FRS2alpha(-/-) mouse embryos. We propose that the FRS2 family proteins have distinct roles in vivo through activation of common signaling proteins including MAP kinase.
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Stimulation of phosphatidylinositol 3-kinase by fibroblast growth factor receptors is mediated by coordinated recruitment of multiple docking proteins.
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: S. H. Ong, Noriko Gotoh, Joseph Schlessinger, Y. R. Hadari, G. R. Guy, Irit LaxAbstract:The docking protein FRS2 is a major downstream effector that links fibroblast growth factor (FGF) and nerve growth factor receptors with the Ras/mitogen-activated protein kinase signaling cascade. In this report, we demonstrate that FRS2 also plays a pivotal role in FGF-induced recruitment and activation of phosphatidylinositol 3-kinase (PI3-kinase). We demonstrate that tyrosine phosphorylation of FRS2α leads to Grb2-mediated complex formation with the docking protein Gab1 and its tyrosine phosphorylation, resulting in the recruitment and activation of PI3-kinase. Furthermore, Grb2 bound to tyrosine-phosphorylated FRS2 through its SH2 domain interacts primarily via its carboxyl-terminal SH3 domain with a proline-rich region in Gab1 and via its amino-terminal SH3 domain with the nucleotide exchange factor Sos1. Assembly of FRS2α:Grb2:Gab1 complex induced by FGF stimulation results in activation of PI3-kinase and downstream effector proteins such as the S/T kinase Akt, whose cellular localization and activity are regulated by products of PI3-kinase. These experiments reveal a unique mechanism for generation of signal diversity by growth factor-induced coordinated assembly of a multidocking protein complex that can activate the Ras/mitogen-activated protein kinase cascade to induce cell proliferation and differentiation, and PI3-kinase to activate a mediator of a cell survival pathway.
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FRS2 proteins recruit intracellular signaling pathways by binding to diverse targets on fibroblast growth factor and nerve growth factor receptors.
Molecular and cellular biology, 2000Co-Authors: S. H. Ong, Noriko Gotoh, Joseph Schlessinger, Y. R. Hadari, G. R. Guy, Shaked Laks, Irit LaxAbstract:The docking protein FRS2 was implicated in the transmission of extracellular signals from the fibroblast growth factor (FGF) or nerve growth factor (NGF) receptors to the Ras/mitogen-activated protein kinase signaling cascade. The two members of the FRS2 family, FRS2α and FRS2β, are structurally very similar. Each is composed of an N-terminal myristylation signal, a phosphotyrosine-binding (PTB) domain, and a C-terminal tail containing multiple binding sites for the SH2 domains of the adapter protein Grb2 and the protein tyrosine phosphatase Shp2. Here we show that the PTB domains of both the α and β isoforms of FRS2 bind directly to the FGF or NGF receptors. The PTB domains of the FRS2 proteins bind to a highly conserved sequence in the juxtamembrane region of FGFR1. While FGFR1 interacts with FRS2 constitutively, independent of ligand stimulation and tyrosine phosphorylation, NGF receptor (TrkA) binding to FRS2 is strongly dependent on receptor activation. Complex formation with TrkA is dependent on phosphorylation of Y490, a canonical PTB domain binding site that also functions as a binding site for Shc (NPXpY). Using deletion and alanine scanning mutagenesis as well as peptide competition assays, we demonstrate that the PTB domains of the FRS2 proteins specifically recognize two different primary structures in two different receptors in a phosphorylation-dependent or -independent manner. In addition, NGF-induced tyrosine phosphorylation of FRS2α is diminished in cells that overexpress a kinase-inactive mutant of FGFR1. This experiment suggests that FGFR1 may regulate signaling via NGF receptors by sequestering a common key element which both receptors utilize for transmitting their signals. The multiple interactions mediated by FRS2 appear to play an important role in target selection and in defining the specificity of several families of receptor tyrosine kinases.
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binding of shp2 tyrosine phosphatase to FRS2 is essential for fibroblast growth factor induced pc12 cell differentiation
Molecular and Cellular Biology, 1998Co-Authors: Y. R. Hadari, Irit Lax, H Kouhara, Joseph SchlessingerAbstract:FRS2 is a lipid-anchored docking protein that plays an important role in linking fibroblast growth factor (FGF) and nerve growth factor receptors with the Ras/mitogen-activated protein (MAP) kinase signaling pathway. In this report, we demonstrate that FRS2 forms a complex with the N-terminal SH2 domain of the protein tyrosine phosphatase Shp2 in response to FGF stimulation. FGF stimulation induces tyrosine phosphorylation of Shp2, leading to the formation of a complex containing Grb2 and Sos1 molecules. In addition, a mutant FRS2 deficient in both Grb2 and Shp2 binding induces a weak and transient MAP kinase response and fails to induce PC12 cell differentiation in response to FGF stimulation. Furthermore, FGF is unable to induce differentiation of PC12 cells expressing an FRS2 point mutant deficient in Shp2 binding. Finally, we demonstrate that the catalytic activity of Shp2 is essential for sustained activation of MAP kinase and for potentiation of FGF-induced PC12 cell differentiation. These experiments demonstrate that FRS2 recruits Grb2 molecules both directly and indirectly via complex formation with Shp2 and that Shp2 plays an important role in FGF-induced PC12 cell differentiation.
Masahide Takahashi - One of the best experts on this subject based on the ideXlab platform.
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Identification of SNT/FRS2 docking site on RET receptor tyrosine kinase and its role for signal transduction
Oncogene, 2001Co-Authors: Kei Kurokawa, Toshihide Iwashita, Hideki Murakami, Hironori Hayashi, Kumi Kawai, Masahide TakahashiAbstract:SNT/FRS2 is a lipid anchored docking protein that contains an amino-terminal myristylation signal, followed by a phosphotyrosine-binding (PTB) domain and a carboxy-terminal region with multiple tyrosine residues. Here we show that the SNT/FRS2 PTB domain binds to RET receptor tyrosine kinase activated by glial cell line-derived neurotrophic factor (GDNF) or multiple endocrine neoplasia (MEN) 2 mutations. Analyses by site directed-mutagenesis revealed that it binds to tyrosine 1062 in RET that is also known to be a binding site for the SHC adaptor protein. Whereas SHC bound to RET was associated with GRB2 and GAB1 proteins, SNT/FRS2 was associated with GRB2 only, suggesting that SNT/FRS2 is involved mainly in the activation of the RAS/mitogen activated protein kinase (MAPK) pathway but not the phosphatidylinositol 3-kinase (PI3-K)/AKT pathway. In addition, phosphorylated SNT/FRS2 appeared to directly complex with SHP-2 tyrosine phosphatase. These results suggest that tyrosine 1062 in RET provides a site for the interaction of multiple signaling molecules and that the balance of SHC and SNT/FRS2 binding may affect the nature of the intracellular signaling for cell proliferation, differentiation and survival induced by activated RET.
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identification of snt FRS2 docking site on ret receptor tyrosine kinase and its role for signal transduction
Oncogene, 2001Co-Authors: Kei Kurokawa, Toshihide Iwashita, Hideki Murakami, Hironori Hayashi, Kumi Kawai, Masahide TakahashiAbstract:SNT/FRS2 is a lipid anchored docking protein that contains an amino-terminal myristylation signal, followed by a phosphotyrosine-binding (PTB) domain and a carboxy-terminal region with multiple tyrosine residues. Here we show that the SNT/FRS2 PTB domain binds to RET receptor tyrosine kinase activated by glial cell line-derived neurotrophic factor (GDNF) or multiple endocrine neoplasia (MEN) 2 mutations. Analyses by site directed-mutagenesis revealed that it binds to tyrosine 1062 in RET that is also known to be a binding site for the SHC adaptor protein. Whereas SHC bound to RET was associated with GRB2 and GAB1 proteins, SNT/FRS2 was associated with GRB2 only, suggesting that SNT/FRS2 is involved mainly in the activation of the RAS/mitogen activated protein kinase (MAPK) pathway but not the phosphatidylinositol 3-kinase (PI3-K)/AKT pathway. In addition, phosphorylated SNT/FRS2 appeared to directly complex with SHP-2 tyrosine phosphatase. These results suggest that tyrosine 1062 in RET provides a site for the interaction of multiple signaling molecules and that the balance of SHC and SNT/FRS2 binding may affect the nature of the intracellular signaling for cell proliferation, differentiation and survival induced by activated RET.
