Fig. 5: METTL3-deficient NK cells are hyporesponsive to IL-15 stimulation.

a Fold changes of cytokine expression in tumor-bearing liver tissue (n = 4) from WT mice injected with 2 × 10⁵ MC38 cells into the spleen 22 days previously, compared with normal liver tissue (n = 4), were determined by RT-qPCR, normalized to β-actin expression. b–d WT (n = 5/group) or cKO mice (n = 6 for pLIVE group; n = 4 for the pLIVE-IL-15 group) that received a hydrodynamic injection of pLIVE-IL-15 or pLIVE control plasmid 1 month previously were harvested for flow-cytometric analyses. b Representative plots showing expression of NK1.1 and CD3 in liver mononuclear cells from WT and cKO mice. c Percentages or absolute numbers of liver NK cells from WT and cKO mice. d Percentages of CD107a-, GzmB-, IFN-γ-, and Perforin-positive NK cells among total NK cells in splenocytes 4 h after stimulated with PMA and ionomycin. e–h Splenocytes from WT or cKO mice were cultured with the presence or absence of rmIL-15 (100 ng/mL) for the indicated times, and then analyzed by flow cytometry. Percentages (e) and absolute numbers (f) of NK cells among splenocytes are shown (n = 4/group). g Percentages of Ki67-positive cells among NK cells (n = 3/group). h Percentages of Annexin V-positive cells among NK cells (n = 4/group). i, j Splenocytes from WT mice or cKO mice were stimulated with rmIL-15 (10 ng/mL) for 7 days, and then collected for stimulation with PMA and ionomycin, followed by flow cytometric analyses. Representative plots (i) and percentages (j) of expression of GzmB, IFN-γ, and TNF in NK cells from WT and cKO mice (n = 4/group). k Protein concentration of GzmB and IFN-γ in the supernatant of cultured NK cells in the condition of rmIL-15 (50 ng/mL) for 9 days from WT (n = 4) or cKO (n = 6) mice. Each symbol represents an individual mouse (c, d) or an individual well of a cell culture plate (e–h, j, k). Data are the mean ± SEM (ns, not significant; unpaired two-tailed t test (a, j, k) or one-way ANOVA (c, d) or two-way ANOVA (e–h)). Source data are provided as a Source Data file. Data represent at least two independent experiments (a–k).