Regulation of Ly49D/DAP12 signal transduction by Src-family kinases and CD45.

Abstract	Activating, DAP12-coupled members of the Ly-49 family of NK cell receptors help control viral infections in mice. However, the kinases and/or phosphatases mediating tyrosine phosphorylation of Ly-49D-associated DAP12 have not been elucidated. In this study, we show for the first time that Src family tyrosine kinases are physically and functionally associated with Ly-49D/DAP12 signaling in murine NK cells. Specifically, we demonstrate the following: 1) inhibition of Src family kinases suppresses DAP12 phosphorylation and downstream DAP12 signals; 2) both Fyn and Lck are capable of phosphorylating DAP12; and 3) both kinases coimmunoprecipitate with the Ly-49D/DAP12 complex in NK cells. Although we detect enhanced phosphorylation of Fyn upon Ly-49D cross-linking in NK cells, Ly-49D-mediated events in both Fyn-/- and Fyn/Lck-/- mice appear normal, reinforcing the theme of redundancy in the ability of Src family kinases to initiate activation events. In contrast to disruption of specific Src family enzymes, Ly-49D/DAP12-mediated calcium mobilization and cytokine production by CD45 null NK cells are defective. Although others have ascribed the effects of CD45 mutation solely on the suppression of Src family activity, we demonstrate in this study that DAP12 is hyperphosphorylated in CD45 null NK cells, resulting in uncoordinated tyrosine-mediated signaling upon Ly-49D ligation. Therefore, although our data are consistent with a Src kinase activity proximally within DAP12 signaling, DAP12 also appears to be a substrate of CD45, suggesting a more complex role for this phosphatase than has been reported previously.
Authors	Llewellyn H Mason, Jami Willette-Brown, Lynn S Taylor, Daniel W McVicar
Journal	Journal of immunology (Baltimore, Md. : 1950) (J Immunol) Vol. 176 Issue 11 Pg. 6615-23 (Jun 01 2006) ISSN: 0022-1767 [Print] United States
PMID	16709819 (Publication Type: Journal Article, Research Support, N.I.H., Intramural)
Chemical References	AG 1879 Adaptor Proteins, Signal Transducing Antibodies, Monoclonal Antigens, Ly Cross-Linking Reagents Intracellular Signaling Peptides and Proteins Klra4 protein, mouse Lectins, C-Type NK Cell Lectin-Like Receptor Subfamily A Pyrimidines Receptors, NK Cell Lectin-Like Tyrobp protein, mouse Tyrosine Protein-Tyrosine Kinases Fyn protein, mouse Lymphocyte Specific Protein Tyrosine Kinase p56(lck) Proto-Oncogene Proteins c-fyn SYK protein, human Syk Kinase Syk protein, mouse src-Family Kinases Leukocyte Common Antigens
Topics	Adaptor Proteins, Signal Transducing (antagonists & inhibitors, metabolism, physiology) Animals Antibodies, Monoclonal (metabolism) Antigens, Ly (immunology, metabolism, physiology) Cell Line Cells, Cultured Cross-Linking Reagents (metabolism) Cytotoxicity Tests, Immunologic Down-Regulation (immunology) Humans Intracellular Signaling Peptides and Proteins (antagonists & inhibitors, physiology) Killer Cells, Natural (enzymology, immunology, metabolism) Lectins, C-Type (immunology, metabolism, physiology) Leukocyte Common Antigens (genetics, physiology) Lymphocyte Specific Protein Tyrosine Kinase p56(lck) (physiology) Mice Mice, Inbred C57BL Mice, Knockout NK Cell Lectin-Like Receptor Subfamily A Phosphorylation Protein-Tyrosine Kinases (antagonists & inhibitors, physiology) Proto-Oncogene Proteins c-fyn (deficiency, genetics, physiology) Pyrimidines (pharmacology) Receptors, NK Cell Lectin-Like Signal Transduction (immunology) Syk Kinase Tyrosine (metabolism) src-Family Kinases (antagonists & inhibitors, physiology)

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.

Realize the full power of the drug-disease research graph!