IkappaB kinase beta phosphorylates Dok1 serines in response to TNF, IL-1, or gamma radiation.
Dok1 is an abundant Ras-GTPase-activating protein-associated tyrosine kinase substrate that negatively regulates cell growth and promotes migration. We now find that IkappaB kinase beta (IKKbeta) associated with and phosphorylated Dok1 in human epithelial cells and B lymphocytes. IKKbeta phosphorylation of Dok1 depended on Dok1 S(439), S(443), S(446), and S(450). Recombinant IKKbeta also phosphorylated Dok1 or Dok1 amino acids 430-481 in vitro. TNF-alpha, IL-1, gamma radiation, or IKKbeta overexpression phosphorylated Dok1 S(443), S(446), and S(450) in vivo, as detected with Dok1 phospho-S site-specific antisera. Moreover, Dok1 with S(439), S(443), S(446), and S(450) mutated to A was not phosphorylated by IKKbeta in vivo. Surprisingly, mutant Dok1 A(439), A(443), A(446), and A(450) differed from wild-type Dok1 in not inhibiting platelet-derived growth factor-induced extracellular signal-regulated kinase 1/2 phosphorylation or cell growth. Mutant Dok1 A(439), A(443), A(446), and A(450) also did not promote cell motility, whereas wild-type Dok1 promoted cell motility, and Dok1 E(439), E(443), E(446), and E(450) further enhanced cell motility. These data indicate that IKKbeta phosphorylates Dok1 S(439)S(443) and S(446)S(450) after TNF-alpha, IL-1, or gamma-radiation and implicate the critical Dok1 serines in Dok1 effects after tyrosine kinase activation.
Lee
Sanghoon
S
International Agency for Research on Cancer, 150 Cours Albert Thomas, 69008 Lyon, France.
Andrieu
Charlotte
C
Saltel
Frédéric
F
Destaing
Olivier
O
Auclair
Jessie
J
Pouchkine
Véronique
V
Michelon
Jocelyne
J
Salaun
Bruno
B
Kobayashi
Ryuji
R
Jurdic
Pierre
P
Kieff
Elliott D
ED
Sylla
Bakary S
BS
D002460:Cell Line; D002465:Cell Movement; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005720:Gamma Rays; D006801:Humans; D051550:I-kappa B Kinase; D007375:Interleukin-1 / Q000494:pharmacology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D010768:Phosphoserine / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D004268:DNA-Binding Proteins; C489560:DOK1 protein, human; D007375:Interleukin-1; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; D016601:RNA-Binding Proteins; D014409:Tumor Necrosis Factor-alpha; D010768:Phosphoserine; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3