Differential requirement for the SAP-Fyn interaction during NK T cell development and function.
The adaptor molecule SAP (signaling lymphocytic activation molecule-associated protein) plays a critical role during NK T (NKT) cell development in humans and mice. In CD4(+) T cells, SAP interacts with the tyrosine kinase Fyn to deliver signals required for TCR-induced Th2-type cytokine production. To determine whether the SAP-dependent signals controlling NKT cell ontogeny rely on its binding to Fyn, we used the OP9-DL1 system to initiate structure function studies of SAP in murine NKT cell development. In cultures containing wild-type (WT) hematopoietic progenitors, we noted the transient emergence of cells that reacted with the NKT cell-specific agonist alpha-galactosyl ceramide and its analog PBS57. Sap(-/-) cells failed to give rise to NKT cells in vitro; however, their development could be rescued by re-expression of WT SAP. Emergence of NKT cells was also restored by a mutant version of SAP (SAP R78A) that cannot bind to Fyn, but with less efficiency than WT SAP. This finding was accentuated in vivo in Sap(R78A) knock-in mice as well as Sap(R78A) competitive bone marrow chimeras, which retained NKT cells but at significantly reduced numbers compared with controls. Unlike Sap(R78A) CD4(+) T cells, which produce reduced levels of IL-4 following TCR ligation, alpha-galactosyl ceramide-stimulated NKT cells from the livers and spleens of Sap(R78A) mice produced Th2 cytokines and activated NK cells in a manner mimicking WT cells. Thus, SAP appears to use differential signaling mechanisms in NKT cells, with optimal ontogeny requiring Fyn binding, while functional responses occur independently of this interaction.
Nunez-Cruz
Selene
S
Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
Yeo
W C Janice
WC
Rothman
Jennifer
J
Ojha
Priti
P
Bassiri
Hamid
H
Juntilla
Marisa
M
Davidson
Dominique
D
Veillette
André
A
Koretzky
Gary A
GA
Nichols
Kim E
KE
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D018920:Coculture Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D051076:Proto-Oncogene Proteins c-fyn / Q000172:deficiency / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*
D047908:Intracellular Signaling Peptides and Proteins; C499569:Sh2d1a protein, mouse; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn