Related Experiment Video
Updated: Jun 6, 2026
Flow Cytometry-based Assay for the Monitoring of NK Cell Functions
Published on: October 30, 2016
Cutting edge: NKp80 uses an atypical hemi-ITAM to trigger NK cytotoxicity
Kevin M Dennehy1, Sascha N Klimosch, Alexander Steinle
1Department of Immunology, University of Tübingen, 72076 Tübingen, Germany.
Insights
Natural killer (NK) cell receptor NKp80 triggers cytotoxicity via an atypical hemi-ITAM motif and Syk kinase. This pathway is crucial for NK cell immune responses.
Area of Science:
- Immunology
- Cellular Signaling
- Molecular Biology
Background:
- The human NK cell receptor NKp80 activates cytotoxicity when binding its ligand AICL.
- The precise signaling mechanisms of NKp80 remain largely uncharacterized.
Purpose of the Study:
- To elucidate the signaling pathways governed by NKp80 in NK cells.
- To identify key molecular players involved in NKp80-mediated cytotoxicity.
Main Methods:
- Utilized the NK92MI cell line for signaling studies.
- Investigated NKp80 tyrosine phosphorylation and its functional consequences using mutant variants.
- Analyzed kinase binding and phosphorylation (Syk, Lck, ZAP-70) upon NKp80 engagement.
- Assessed the impact of Syk kinase inhibition on NKp80-induced cytotoxicity.
Main Results:
- NKp80 requires tyrosine phosphorylation at position 7 for cytotoxicity.
- The hemi-ITAM-like motif of NKp80 binds Lck and Syk kinases.
- NKp80 engagement leads to Syk phosphorylation, which is essential for cytotoxicity.
- Syk kinase inhibition abrogates NKp80-mediated cytotoxic activity, while ZAP-70 inhibition does not.
Conclusions:
- NKp80 signaling employs an atypical hemi-ITAM motif that recruits and activates Syk kinase.
- Syk kinase is a critical mediator of NKp80-induced cellular cytotoxicity.
- Understanding this pathway provides insights into NK cell immune function.
Abstract:
The human NK cell receptor NKp80 stimulates cytotoxicity upon engagement of its genetically linked ligand AICL. However, the mechanisms underlying NKp80-mediated signaling are unknown. In this study, we dissected NKp80 signaling using the NK cell line NK92MI. We demonstrated that NKp80, but not NKp80 mutated at tyrosine 7 (NKp80/Y7F), is tyrosine phosphorylated. Accordingly, NKp80/Y7F, but not NKp80/Y30F or NKp80/Y37F, failed to induce cytotoxicity. NKp80 phosphopeptides comprising the hemi-ITAM-like sequence surrounding tyrosine 7 bound Lck- and Syk-family kinases; accordingly, cross-linking of NKp80, but not NKp80/Y7F, induced Syk phosphorylation. Moreover, inhibition of Syk kinase, but not ZAP-70 kinase, impaired cytotoxic responses through NKp80. Atypical residues in the hemi-ITAM-like motif of NKp80 cause an altered stoichiometry of phosphorylation but did not substantially affect NK cytotoxicity. Altogether, these results show that NKp80 uses an atypical hemi-ITAM and Syk kinase to trigger cellular cytotoxicity.
Related Concept Videos
01:28Cells of the Innate Immune Response
Phagocytes
Phagocytes police the peripheral tissues by removing cellular debris and responding to the invasion of foreign substances or pathogens. Many phagocytes attack and remove microorganisms even before lymphocytes detect them. The human body has two general...
01:27Cytotoxic T Cells-mediated Immune Response
Immunological surveillance is the ability of immune cells to monitor and eliminate infected cells with intracellular pathogens, neoplastically transformed cells, and cells with non-self antigens. Cytotoxic T cells and NK...
01:25Immune Surveillance by NK Cells and Phagocytes
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...