Related Experiment Video
Updated: Jul 11, 2026
Quantification of the Respiratory Burst Response as an Indicator of Innate Immune Health in Zebrafish
Published on: September 12, 2013
The zebrafish activating immune receptor Nitr9 signals via Dap12
Sheng Wei1, Jun-Min Zhou, Xinghong Chen
1Immunology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Avenue, Tampa, FL 33612, USA.
Abstract:
Both inhibitory and activating forms of natural killer (NK) cell receptors are found in mammals. The activating receptors play a direct role in the recognition of virally infected or transformed cells and transduce activating signals into the cell by partnering with an adaptor protein, which contains a cytoplasmic activation motif. Activating NK receptors encoded by the mammalian leukocyte receptor complex (e.g., killer cell immunoglobulin-like receptors) and the natural killer complex (e.g., Ly49s) partner with the adaptor protein DAP12, whereas NK receptors encoded in the CD94/NKG2 complex partner with the adaptor protein DAP10. Novel immune-type receptors (NITRs) found in bony fish share several common features with immunoglobulin-type NK receptors. Nitr9 is a putative activating receptor in zebrafish that induces cytotoxicity within the context of human NK cells. One isoform of Nitr9, Nitr9L, is shown here to preferentially partner with a zebrafish ortholog of Dap12. Cross-linking the Nitr9L-Dap12 complex results in activation of the phosphytidylinositol 3-kinase-->AKT-->extracellular signal-regulated kinase pathway suggesting that the DAP12-based activating pathway is conserved between bony fish and mammals.
Insights
Natural killer (NK) cell activating receptors in zebrafish, specifically Nitr9L, partner with Dap12. This interaction activates signaling pathways, suggesting conserved NK cell activation mechanisms between fish and mammals.
Area of Science:
- Immunology
- Comparative genomics
- Cell signaling
Background:
- Activating natural killer (NK) cell receptors recognize and eliminate abnormal cells.
- Mammalian NK receptors utilize adaptor proteins like DAP12 or DAP10 for signal transduction.
- Novel immune-type receptors (NITRs) in fish share similarities with mammalian NK receptors.
Purpose of the Study:
- To investigate the function of zebrafish Nitr9, a putative activating NK receptor.
- To determine the adaptor protein partnered by the zebrafish Nitr9L isoform.
- To explore the conservation of DAP12-mediated signaling pathways across species.
Main Methods:
- Expression analysis of zebrafish Nitr9 isoforms.
- Co-immunoprecipitation assays to identify interacting partners.
- Stimulation of Nitr9L-Dap12 complex and downstream signaling analysis (PI3K-AKT-ERK pathway).
Main Results:
- Zebrafish Nitr9L preferentially partners with a zebrafish ortholog of Dap12.
- Cross-linking the Nitr9L-Dap12 complex activates the phosphoinositide 3-kinase (PI3K)-->AKT-->extracellular signal-regulated kinase (ERK) pathway.
- This activation mirrors signaling observed in mammalian NK cell activation.
Conclusions:
- The zebrafish Nitr9L-Dap12 complex functions as an activating NK receptor.
- The DAP12-based activating pathway is evolutionarily conserved between bony fish and mammals.
- This study provides insights into the ancient origins of NK cell immunity.
