Src homology region 2 (SH2) domain-containing phosphatase-1 dephosphorylates B cell linker protein/SH2 domain leukocyte protein of 65 kDa and selectively regulates c-Jun NH2-terminal kinase activation in B cells.
Src homology region 2 (SH2) domain-containing phosphatase-1 (SHP-1) is a cytosolic protein tyrosine phosphatase containing two SH2 domains in its NH2 terminus. That immunological abnormalities of the motheaten and viable motheaten mice are caused by mutations in the gene encoding SHP-1 indicates that SHP-1 plays important roles in lymphocyte differentiation, proliferation, and activation. To elucidate molecular mechanisms by which SHP-1 regulates BCR-mediated signal transduction, we determined SHP-1 substrates in B cells using the substrate-trapping approach. When the phosphatase activity-deficient form of SHP-1, in which the catalytic center cysteine (C453) was replaced with serine (SHP-1-C/S), was introduced in WEHI-231 cells, tyrosine phosphorylation of a protein of about 70 kDa was strongly enhanced. Immunoprecipitation and Western blot analyses revealed that this protein is the B cell linker protein (BLNK), also named SH2 domain leukocyte protein of 65 kDa, and that upon tyrosine phosphorylation BLNK binds to SHP-1-C/S in vitro. In vitro kinase assays demonstrated that hyperphosphorylation of BLNK in SHP-1-C/S-expressing cells was not due to enhanced activity of Lyn or Syk. Furthermore, BCR-induced activation of c-Jun NH2-terminal kinase was shown to be significantly enhanced in SHP-1-C/S transfectants. Taken collectively, our results suggest that BLNK is a physiological substrate of SHP-1 in B cells and that SHP-1 selectively regulates c-Jun NH2-terminal kinase activation.
Mizuno
K
K
Department of Immunology and Signal Transduction, Tokyo Metropolitan Institute for Neuroscience, Tokyo Metropolitan Organization for Medical Research, Fuchu, Tokyo, Japan.
Tagawa
Y
Y
Mitomo
K
K
Arimura
Y
Y
Hatano
N
N
Katagiri
T
T
Ogimoto
M
M
Yakura
H
H
D048868:Adaptor Proteins, Signal Transducing; D019943:Amino Acid Substitution / Q000235:genetics / Q000276:immunology; D001402:B-Lymphocytes / Q000201:enzymology* / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D003545:Cysteine / Q000235:genetics; D004789:Enzyme Activation / Q000276:immunology; D004792:Enzyme Precursors / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D008024:Ligands; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008970:Molecular Weight; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D054645:Protein Phosphatase 1; D017434:Protein Structure, Tertiary; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011947:Receptors, Antigen, B-Cell / Q000276:immunology / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D012694:Serine / Q000235:genetics; D013379:Substrate Specificity / Q000276:immunology; D000072377:Syk Kinase; D014162:Transfection; D014407:Tumor Cells, Cultured; D018909:src Homology Domains / Q000276:immunology*; D019061:src-Family Kinases / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; C113939:B cell linker protein; D002352:Carrier Proteins; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D010750:Phosphoproteins; D011947:Receptors, Antigen, B-Cell; D012694:Serine; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; C000606897:Syk protein, mouse; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D054645:Protein Phosphatase 1; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D003545:Cysteine