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SHP-2 binds to Tyr763 and Tyr1009 in the PDGF β-receptor and mediates PDGF-induced activation of the Ras/MAP kinase pathway and chemotaxis
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm , Ludwig Institute for Cancer Research.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Pharmacology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm , Ludwig Institute for Cancer Research.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm , Ludwig Institute for Cancer Research.
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1999 (English)In: Oncogene, ISSN 0950-9232, Vol. 18, no 25, 3696-3702 p.Article in journal (Refereed) Published
Abstract [en]

Activation of the beta-receptor for platelet-derived growth factor (PDGF) by its ligand leads to autophosphorylation on a number of tyrosine residues. Here we show that Tyr763 in the kinase insert region is a novel autophosphorylation site, which after phosphorylation binds the protein tyrosine phosphatase SHP-2. SHP-2 has also previously been shown to bind to phosphorylated Tyr1009 in the PDGF beta-receptor. Porcine aortic endothelial (PAE) cells transfected with a PDGF beta-receptor in which Tyr763 and Tyr1009 were mutated to phenylalanine residues failed to associate with SHP-2 after ligand stimulation. Moreover, PDGF-BB-induced Ras GTP-loading and Erk2 activation were severely compromised in the receptor mutant. Whereas the mitogenic response to PDGF-BB remained at the same level as in cells expressing wild-type PDGF beta-receptor, chemotaxis induced by PDGF-BB was significantly decreased in the case of the Y763F/Y1009F mutant cells, suggesting an important role for SHP-2 in chemotactic signaling.

Place, publisher, year, edition, pages
Stockton Press , 1999. Vol. 18, no 25, 3696-3702 p.
Keyword [en]
PDGF beta-receptor; SHP-2; chemotaxis; Ras/MAP kinase pathway
Identifiers
URN: urn:nbn:se:uu:diva-91007PubMedID: 10391677OAI: oai:DiVA.org:uu-91007DiVA: diva2:163570
Available from: 2003-10-23 Created: 2003-10-23 Last updated: 2009-09-23Bibliographically approved
In thesis
1. Modulation of PDGF Receptor Signaling via the Phosphatase SHP-2 and the Docking Protein Gab1
Open this publication in new window or tab >>Modulation of PDGF Receptor Signaling via the Phosphatase SHP-2 and the Docking Protein Gab1
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Modulering av PDGF receptorsignalering via fosfataset SHP-2 och dockingproteinet Gab1
Abstract [sv]

x

Abstract [en]

Platelet-derived growth factors (PDGF), a family of potent mitogens and chemoattractants for cells of mesenchymal origin, elicit their biological effects through the binding of two related receptor tyrosine kinases, denoted α- and β-receptors. The binding of PDGF to the receptors causes receptor dimerization and autophosphorylation on tyrosine residues. Src homology 2 (SH2) domain-containing proteins then bind the phosphorylated receptors, mediating further propagation of the signal. This thesis describes how the interaction between the PDGF receptors and some of their downstream targets can modify the cellular response to PDGF.

The tyrosine phosphatase SHP-2 has been implicated in activation of the Ras/MAPK pathway downstream of several receptor tyrosine kinases. We found that SHP-2 binds to phosphorylated Y763 in the PDGF β-receptor, in addition to the already reported binding to Y1009. Cells expressing PDGF β-receptors with Y763 and Y1009 mutated to phenylalanine exhibited decreased Ras-GTP loading and reduced activation of Erk2 in response to PDGF. Whereas these cells did not show any change in the mitogenic response to PDGF, the PDGF-induced chemotaxis was significantly reduced in cells expressing mutant compared to wild-type receptor.

The phosphorylation of Y771 of the PDGF β-receptor had been shown to be significantly lower in the αβ-heterodimeric receptor compared to in the ββ-homodimer, causing reduced binding of RasGAP to the heterodimer and increased Ras/MAPK activation. We could demonstrate that the reduced phosphorylation of Y771 is due to dephosphorylation by tyrosine phosphatases, including SHP-2.

SHP-2 had been shown to associate with the docking protein Gab1 after growth factor stimulation. We showed that the adaptor protein Grb2 was required for PDGF mediated phosphorylation of Gab1, and that phosphorylated Gab1, Grb2 and SHP-2 create a complex upon PDGF stimulation. Using a cell system with an inducible Gab1 expression, we further demonstrated that Gab1 increased SHP-2 activity in response to PDGF, without affecting the interaction between SHP-2 and the b-receptor. Induction of Gab1 correlated with an increase in both PDGF-induced Erk and p38 MAPK activation, whereas Akt activation was unaffected. The latter finding was in line with our observation that PDGF had no effect on the interaction between Gab1 and p85 of PI3’-kinase. The increase in MAPK activity after Gab1 induction and PDGF treatment did not correlate with an increase in PDGF-induced mitogenicity; instead these cells displayed more pronounced actin reorganization in response to PDGF.

In conclusion, our data indicate that SHP-2 regulates the PDGF response both through direct dephosphorylation of the receptor and through its interaction with Gab1. PDGF stimulated activation of SHP-2 seems to be correlated not only with mitogenesis, but also with reorganization of the actin cytoskeleton and cell migration.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 68 p.
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 0282-7476 ; 1300
Keyword
Cell and molecular biology, PDGF, SHP-2, Gab1, chemotaxis, actin reorganization, Cell- och molekylärbiologi
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-3748 (URN)91-554-5780-0 (ISBN)
Public defence
2003-11-14, B41, BMC, Uppsala, 09:15
Opponent
Supervisors
Available from: 2003-10-23 Created: 2003-10-23Bibliographically approved

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