The adaptor protein Gads (Grb2-related adaptor downstream of Shc) is implicated in coupling hemopoietic progenitor kinase-1 to the activated TCR.
The hemopoietic-specific Gads (Grb2-related adaptor downstream of Shc) adaptor protein possesses amino- and carboxyl-terminal Src homology 3 (SH3) domains flanking a central SH2 domain and a unique region rich in glutamine and proline residues. Gads functions to couple the activated TCR to distal signaling events through its interactions with the leukocyte-specific signaling proteins SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) and LAT (linker for activated T cells). Expression library screening for additional Gads-interacting molecules identified the hemopoietic progenitor kinase-1 (HPK1), and we investigated the HPK1-Gads interaction within the DO11.10 murine T cell hybridoma system. Our results demonstrate that HPK1 inducibly associates with Gads and becomes tyrosine phosphorylated following TCR activation. HPK1 kinase activity is up-regulated in response to activation of the TCR and requires the presence of its proline-rich motifs. Mapping experiments have revealed that the carboxyl-terminal SH3 domain of Gads and the fourth proline-rich region of HPK1 are essential for their interaction. Deletion of the fourth proline-rich region of HPK1 or expression of a Gads SH2 mutant in T cells inhibits TCR-induced HPK1 tyrosine phosphorylation. Together, these data suggest that HPK1 is involved in signaling downstream from the TCR, and that SH2/SH3 domain-containing adaptor proteins, such as Gads, may function to recruit HPK1 to the activated TCR complex.
Liu
S K
SK
Department of Medical Biophysics and The Arthur and Sonia Labatt Brain Tumor Research Center, Hospital for Sick Children Research Institute, University of Toronto, Toronto, Ontario, Canada.
Smith
C A
CA
Arnold
R
R
Kiefer
F
F
McGlade
C J
CJ
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002460:Cell Line; D004789:Enzyme Activation / Q000235:genetics / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010446:Peptide Fragments / Q000276:immunology / Q000502:physiology; D010766:Phosphorylation; D011392:Proline / Q000378:metabolism / Q000502:physiology; D011485:Protein Binding / Q000276:immunology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology; D014162:Transfection; D014443:Tyrosine / Q000037:antagonists & inhibitors / Q000378:metabolism; D015854:Up-Regulation / Q000276:immunology; D018909:src Homology Domains / Q000235:genetics / Q000276:immunology*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C498726:Mona protein, mouse; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D014443:Tyrosine; D011392:Proline; C102102:hematopoietic progenitor kinase 1; D017346:Protein Serine-Threonine Kinases