title: Grb7 is a downstream signaling component of platelet-derived growth factor alpha- and beta-receptors.
abstract: Ligand stimulation of the platelet-derived growth factor (PDGF) alpha- or beta-receptors leads to activation of their intrinsic tyrosine kinases and autophosphorylation of tyrosine residues. Grb7 is an SH2 and PH domain-containing molecule that is known to be overexpressed in some breast cancer tissues and cell lines. Here we show that the SH2 domain of Grb7 can directly bind to the autophosphorylated PDGF beta-receptor in vitro. Grb7 association to the PDGF beta-receptor was dramatically reduced by replacement of tyrosine residues 716 or 775 with phenylalanine residues. Synthetic phosphorylated peptides containing Tyr-716 or Tyr-775 inhibited binding of the Grb7 SH2 domain to the autophosphorylated PDGF beta-receptor in a manner similar to but distinct from the binding of the Grb2 SH2 domain. Grb7 associated with activated PDGF beta-receptors in vivo, and the association was dramatically reduced by substitution of Tyr-716 or Tyr-775 with a phenylalanine residue. Furthermore, complex formation between Shc and Grb7 was observed after ligand stimulation of PDGF alpha- or beta-receptors in cells transfected with Grb7 cDNA or in the breast cancer cell line BT-474. Thus, Grb7 is implicated in PDGF signaling pathways in certain cell types by binding to the receptor directly or indirectly via Shc.
authors.affiliation: Ludwig Institute for Cancer Research, Biomedical Center, S-751 24 Uppsala, Sweden. kyotoe@intmed02.m.chiba-u.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Yokote
authors.forename: B
authors.initials: B
authors.lastname: Margolis
authors.forename: C H
authors.initials: CH
authors.lastname: Heldin
authors.forename: L
authors.initials: L
authors.lastname: Claesson-Welsh
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism; D004730:Endothelium, Vascular; D051382:GRB7 Adaptor Protein; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010748:Phosphopeptides / Q000378:metabolism; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism / Q000502:physiology*; D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism*; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013552:Swine; D014407:Tumor Cells, Cultured; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; C495955:GRB7 protein, human; D010455:Peptides; D010748:Phosphopeptides; D011506:Proteins; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D051382:GRB7 Adaptor Protein; D019000:Phosphotyrosine; D020796:Receptor, Platelet-Derived Growth Factor alpha; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor