Dok-1 independently attenuates Ras/mitogen-activated protein kinase and Src/c-myc pathways to inhibit platelet-derived growth factor-induced mitogenesis.
The Dok adaptor proteins play key regulatory roles in receptor and non-receptor kinase-initiated signaling pathways. Dok-1, the prototype member of this family, negatively regulates cell proliferation elicited by numerous growth factors, including platelet-derived growth factor (PDGF). However, how Dok-1 exerts its negative effect on mitogenesis has remained elusive. Using Dok-1 knockout cells and Dok-1 mutants deficient in binding to specific Dok-1-interacting proteins, we show that Dok-1 interferes with PDGF-stimulated c-myc induction and Ras/mitogen-activated protein kinase (MAPK) activation by tethering different signaling components to the cell membrane. Specifically, Dok-1 attenuates PDGF-elicited c-myc induction by recruiting Csk to active Src kinases, whereupon their activities and consequent c-myc induction are diminished. On the other hand, Dok-1 negatively regulates PDGF-induced MAPK activation by acting on Ras-GAP and at least one other Dok-1-interacting protein. Importantly, we demonstrate that Dok-1's actions on both of these signaling pathways contribute to its inhibitory effect on mitogenesis. Our data suggest a mechanistic basis for the inhibitory effect of Dok-1 on growth factor-induced mitogenesis and its role as a tumor suppressor.
Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA.
Mingming
M
Zhao
Justyna A
JA
Janas
Masaru
M
Niki
Pier Paolo
PP
Pandolfi
Linda
L
Van Aelst
D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology; D005786:Gene Expression Regulation / Q000235:genetics; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008938:Mitosis / Q000187:drug effects*; D009154:Mutation / Q000235:genetics; D041681:NIH 3T3 Cells; D010750:Phosphoproteins / Q000172:deficiency / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism*; D019061:src-Family Kinases
D004268:DNA-Binding Proteins; C489560:DOK1 protein, human; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D000081247:CSK Tyrosine-Protein Kinase; D016392:Proto-Oncogene Proteins pp60(c-src); D019061:src-Family Kinases; C000631346:CSK protein, human; D020928:Mitogen-Activated Protein Kinases; D018631:ras Proteins