Negative regulation of natural killer cell function by EAT-2, a SAP-related adaptor.
EAT-2 is an adaptor expressed in innate immune cells, including natural killer (NK) cells. It is closely related to the adaptor SAP, which regulates signaling lymphocyte activation molecule (SLAM)-related receptors by recruiting the kinase FynT to the receptors. Here we have studied the function of EAT-2 in NK cells by creating mice lacking or overexpressing EAT-2. Like SAP, EAT-2 was associated with the SLAM-related receptor 2B4 in NK cells. However, unlike SAP, EAT-2 was an inhibitor of NK cell function. EAT-2 repressed natural cytotoxicity and interferon-gamma secretion by a mechanism involving tyrosine phosphorylation of its C terminus. We have demonstrated a similar function for the adaptor ERT, a newly identified SAP family member expressed in mouse NK cells. These data identify a previously unknown mechanism of NK cell inhibition. Moreover, they indicate that EAT-2 and SAP have distinct and at times opposing functions in natural immunity.
Pubmed ID: 16127454 RIS Download
Adaptor Proteins, Signal Transducing | Amino Acid Sequence | Animals | Animals, Genetically Modified | Antigens, CD | CHO Cells | Cell Line | Cricetinae | Cytotoxicity, Immunologic | Down-Regulation | Interferon-gamma | Intracellular Signaling Peptides and Proteins | Killer Cells, Natural | Membrane Glycoproteins | Mice | Mice, Inbred BALB C | Mice, Knockout | Molecular Sequence Data | Phosphorylation | Receptors, Immunologic | Sequence Alignment | Signaling Lymphocytic Activation Molecule Associated Protein | Signaling Lymphocytic Activation Molecule Family | Transcription Factors | Tyrosine | src Homology Domains