Structural requirements of SLP-76 in signaling via the high-affinity immunoglobulin E receptor (Fc epsilon RI) in mast cells.
The adapter SLP-76 plays an essential role in Fc epsilon RI signaling, since SLP-76(-/-) bone marrow-derived mast cells (BMMC) fail to degranulate and release interleukin-6 (IL-6) following Fc epsilon RI ligation. To define the role of SLP-76 domains and motifs in Fc epsilon RI signaling, SLP-76(-/-) BMMC were retrovirally transduced with SLP-76 and SLP-76 mutants. The SLP-76 N-terminal and Gads binding domains, but not the SH2 domain, were critical for Fc epsilon RI-mediated degranulation and IL-6 secretion, whereas all three domains are essential for T-cell proliferation following T-cell receptor (TCR) ligation. Unexpectedly, the three tyrosine residues in SLP-76 critical for TCR signaling, Y112, Y128, and Y145, were not essential for IL-6 secretion, but were required for degranulation and mitogen-activated protein kinase activation. Furthermore, a Y112/128F SLP-76 mutant, but not a Y145F mutant, strongly reconstituted mast cell degranulation, suggesting a critical role for Y145 in Fc epsilon RI-mediated exocytosis. These results point to important differences in the function of SLP-76 between T cells and mast cells.
Kettner
Alexander
A
Division of Immunology, Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Pivniouk
Vadim
V
Kumar
Lalit
L
Falet
Hervé
H
Lee
Jeng-Shin
JS
Mulligan
Richard
R
Geha
Raif S
RS
D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D001854:Bone Marrow Cells; D002118:Calcium / Q000378:metabolism; D015550:Cell Degranulation / Q000502:physiology; D002478:Cells, Cultured; D018014:Gene Transfer Techniques; D015850:Interleukin-6 / Q000378:metabolism; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary / Q000502:physiology; D017455:Receptors, IgE / Q000378:metabolism*; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D013329:Structure-Activity Relationship; D010738:Type C Phospholipases / Q000378:metabolism; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D015850:Interleukin-6; D010750:Phosphoproteins; D017455:Receptors, IgE; C092947:SLP-76 signal Transducing adaptor proteins; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D001619:beta-N-Acetylhexosaminidases; D002118:Calcium