Hematopoietic progenitor kinase 1 associates physically and functionally with the adaptor proteins B cell linker protein and SLP-76 in lymphocytes.
B cell linker protein (BLNK) is a SLP-76-related adaptor protein essential for signal transduction from the BCR. To identify components of BLNK-associated signaling pathways, we performed a phosphorylation-dependent yeast two-hybrid analysis using BLNK probes. Here we report that the serine/threonine kinase hematopoietic progenitor kinase 1 (HPK1), which is activated upon antigen-receptor stimulation and which has been implicated in the regulation of MAP kinase pathways, interacts physically and functionally with BLNK in B cells and with SLP-76 in T cells. This interaction requires Tyr(379) of HPK1 and the Src homology 2 (SH2) domain of BLNK/SLP-76. Via homology modeling, we defined a consensus binding site within ligands for SLP family SH2 domains. We further demonstrate that the SH2 domain of SLP-76 participates in the regulation of AP-1 and NFAT activation in response to T cell receptor (TCR) stimulation and that HPK1 inhibits AP-1 activation in a manner partially dependent on its interaction with SLP-76. Our data are consistent with a model in which full activation of HPK1 requires its own phosphorylation on tyrosine and subsequent interaction with adaptors of the SLP family, providing a mechanistic basis for the integration of this kinase into antigen receptor signaling cascades.
Pubmed ID: 11487585 RIS Download
Adaptor Proteins, Signal Transducing | Animals | Binding Sites | Carrier Proteins | Cell Line | DNA, Complementary | Databases as Topic | Enzyme Activation | Humans | Immunoblotting | Jurkat Cells | Lymphocytes | Mice | Mice, Inbred C57BL | Models, Biological | Models, Molecular | Mutagenesis, Site-Directed | Mutation | Phosphoproteins | Precipitin Tests | Protein Binding | Protein Structure, Tertiary | Protein-Serine-Threonine Kinases | Reverse Transcriptase Polymerase Chain Reaction | Sequence Homology, Amino Acid | Signal Transduction | T-Lymphocytes | Transcription Factor AP-1 | Two-Hybrid System Techniques | Up-Regulation | src Homology Domains