Dok-6, a Novel p62 Dok family member, promotes Ret-mediated neurite outgrowth.
Activation of Ret, the receptor-tyrosine kinase for the glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs), results in the recruitment and assembly of adaptor protein complexes that function to transduce signals downstream of the receptor. Here we identify Dok-6, a novel member of the Dok-4/5 subclass of the p62 Dok family of intracellular adaptor molecules, and characterize its interaction with Ret. Expression analysis reveals that Dok-6 is highly expressed in the developing central nervous system and is co-expressed with Ret in several locations, including sympathetic, sensory, and parasympathetic ganglia, as well as in the ureteric buds of the developing kidneys. Pull-down assays using the Dok-6 phosphotyrosine binding (PTB) domain and GDNF-activated Ret indicate that Dok-6 binds to the phosphorylated Ret Tyr(1062) residue. Moreover, ligand activation of Ret resulted in phosphorylation of tyrosine residue(s) located within the unique C terminus of Dok-6 predominantly through a Src-dependent mechanism, indicating that Dok-6 is a substrate of the Ret-Src signaling pathway. Interestingly, expression of Dok-6 potentiated GDNF-induced neurite outgrowth in GDNF family receptor alpha1 (GFRalpha1)-expressing Neuro2A cells that was dependent upon the C-terminal residues of Dok-6. Taken together, these data identify Dok-6 as a novel Dok-4/5-related adaptor molecule that may function in vivo to transduce signals that regulate Ret-mediated processes such as axonal projection.
Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Robert J
RJ
Crowder
Hideki
H
Enomoto
Mao
M
Yang
Eugene M
EM
Johnson
Jeffrey
J
Milbrandt
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D004622:Embryo, Mammalian; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016501:Neurites / Q000648:ultrastructure*; D015513:Oncogene Proteins / Q000502:physiology*; D011485:Protein Binding; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000502:physiology*; D016415:Sequence Alignment; D015398:Signal Transduction; D014018:Tissue Distribution; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; C492987:DOK6 protein, human; D015513:Oncogene Proteins; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; D020794:Receptor Protein-Tyrosine Kinases