title: The inhibitory role of DOC-2/DAB2 in growth factor receptor-mediated signal cascade. DOC-2/DAB2-mediated inhibition of ERK phosphorylation via binding to Grb2.
abstract: DOC-2/DAB2 (differentially expressed in ovarian carcinoma-2/disabled 2) appears to be a potential tumor suppressor gene with a growth inhibitory effect on several cancer types. Previously, we have shown that DOC-2/DAB2 suppresses protein kinase C-induced AP-1 activation, which is modulated by serine 24 phosphorylation in the N terminus of DOC-2/DAB2. However, the functional impact of the C terminus of DOC-2/DAB2, containing three proline-rich domains, has not been explored. In this study, we examined this functional role in modulating signaling mediated by peptide growth factor receptor tyrosine kinase, particularly because it involves the interaction with Grb2. Using sequence-specific peptides, we found that the second proline-rich domain of DOC-2/DAB2 is the key binding site to Grb2 in the presence of growth factors. Such elevated binding interrupts the binding between SOS and Grb2, which consequently suppresses downstream ERK phosphorylation. Reduced ERK phosphorylation was restored when the binding between DOC-2/DAB2 and Grb2 was interrupted by a specific peptide or by increasing the expression of Grb2. Furthermore, the C terminus of the DOC-2/DAB2 construct can inhibit the AP-1 activity elicited by growth factors. We conclude that DOC-2/DAB2, a potent negative regulator, can suppress ERK activation by interrupting the binding between Grb2 and SOS that is elicited by peptide growth factors. This study further illustrates that DOC-2/DAB2 has multiple effects on the RAS-mediated signal cascades active in cancer cells.
authors.affiliation: Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9110, USA.
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: J T
authors.initials: JT
authors.lastname: Hsieh
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001665:Binding Sites; D019556:COS Cells; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism; D051380:GRB2 Adaptor Protein; D017930:Genes, Reporter; D016147:Genes, Tumor Suppressor; D008156:Luciferases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases; D016716:PC12 Cells; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011392:Proline / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017978:Receptors, Growth Factor / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction; D020839:Son of Sevenless Protein, Drosophila / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D051017:Apoptosis Regulatory Proteins; C102885:DAB2 protein, human; D018076:DNA, Complementary; D051380:GRB2 Adaptor Protein; C495950:Grb2 protein, rat; D010455:Peptides; D011506:Proteins; D017978:Receptors, Growth Factor; D011994:Recombinant Proteins; D020839:Son of Sevenless Protein, Drosophila; D025521:Tumor Suppressor Proteins; D004815:Epidermal Growth Factor; D011392:Proline; D008156:Luciferases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases