Innate T cells, NK cells, and innate-like lymphocytes (ILCs) share transcriptional signatures that translate into overlapping developmental and functional programs. A prominent example for genes that are highly expressed in NK cells but not in ILCs is serine-threonine-tyrosine kinase 1 (Styk1 encoded by Styk1). We found Styk1 to be specifically expressed in lymphocytes positive for Killer cell lectin-like receptor subfamily B, member 1, also known as CD161 or NK1.1, i.e. in NK cell, αβ iNKT, and γδ NKT cell lineages. To investigate the role of Styk1 in the development and function of NK1.1+ innate T-cell subsets, we generated and analyzed a novel Styk1null mutant mouse line. Furthermore, we validated Styk1 expression in γδ NKT cells and in thymic, but not in peripheral invariant αβ iNKT cells through ex vivo analysis of a concomitantly generated transgenic Styk1 reporter mouse line. Despite the very specific expression of Styk1 in NK cells, γδ NKT cells, and thymic αβ iNKT, its absence did not alter homeostasis and function of these lineages. Thus, Styk1 expression is specific for NK cells and selected NK-like innate T-cell subsets, but dispensable for their development and function.
Keywords: NK1.1; Styk1; iNKT cells; receptor tyrosine kinase; γδ T cells.
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