Tyrosine phosphorylation of p62(Dok) induced by cell adhesion and insulin: possible role in cell migration.
Dok, a 62-kDa Ras GTPase-activating protein (rasGAP)-associated phosphotyrosyl protein, is thought to act as a multiple docking protein downstream of receptor or non-receptor tyrosine kinases. Cell adhesion to extracellular matrix proteins induced marked tyrosine phosphorylation of Dok. This adhesion-dependent phosphorylation of Dok was mediated, at least in part, by Src family tyrosine kinases. The maximal insulin-induced tyrosine phosphorylation of Dok required a Src family kinase. A mutant Dok (DokDeltaPH) that lacked its pleckstrin homology domain failed to undergo tyrosine phosphorylation in response to cell adhesion or insulin. Furthermore, unlike the wild-type protein, DokDeltaPH did not localize to subcellular membrane components. Insulin promoted the association of tyrosine-phosphorylated Dok with the adapter protein NCK and rasGAP. In contrast, a mutant Dok (DokY361F), in which Tyr361 was replaced by phenylalanine, failed to bind NCK but partially retained the ability to bind rasGAP in response to insulin. Overexpression of wild-type Dok, but not that of DokDeltaPH or DokY361F, enhanced the cell migratory response to insulin without affecting insulin activation of mitogen-activated protein kinase. These results identify Dok as a signal transducer that potentially links, through its interaction with NCK or rasGAP, cell adhesion and insulin receptors to the machinery that controls cell motility.
Noguchi
T
T
Second Department of Internal Medicine, Kobe University School of Medicine, Kusunoki-cho, Chuo-ku, Kobe 650-0017, USA.
Matozaki
T
T
Inagaki
K
K
Tsuda
M
M
Fukunaga
K
K
Kitamura
Y
Y
Kitamura
T
T
Shii
K
K
Yamanashi
Y
Y
Kasuga
M
M
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D016466:CHO Cells; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002448:Cell Adhesion / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D006224:Cricetinae; D017931:DNA Primers / Q000235:genetics; D004268:DNA-Binding Proteins; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D015513:Oncogene Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D016601:RNA-Binding Proteins; D013347:Subcellular Fractions / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D017931:DNA Primers; D004268:DNA-Binding Proteins; C489560:DOK1 protein, human; C489561:Dok1 protein, mouse; C074561:GAP-associated protein p62; D007328:Insulin; C078332:Nck protein; D015513:Oncogene Proteins; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D014443:Tyrosine; D019061:src-Family Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases