Loss of YTHDF2 in DCs induces Gm8909-encoded MHC-I by the Notch signaling pathway. (A) STRING protein–protein interaction network between the MHC-I pathway (involving Gm8909 and H2-Q6) and Notch signaling pathways (involving Mfng, Aph-1b, and Aph-1c). The minimum required interaction score was set to 0.4. k-means clustering was applied. Line thickness denoted the STRING PPI score/confidence. (B) ELISPOT assay on IFN-γ secreted by CD8⁺ T cells cocultured with WT/TriKD DCs, which were previously exposed to irradiated B16F10-OZ cells (n = 3). (C) Gene Set Enrichment Analysis pathway analysis indicating antigen processing and presentation pathway enriched in DCs (cKO+IR versus WT+IR). (D) Heatmap showing the expression of Gm8909, H2-Q6, and other MHC-I relevant genes in tumor-infiltrating DCs from WT and Ythdf2 cKO mice. (E)Gm8909 mRNA expression in WT or Ythdf2-cKO DCs, which were cocultured with irradiated tumor cells. TriKD indicates DC KD with Mfng, Aph-1b, and Aph-1c siRNA (n = 3). (F) ELISPOT assay on IFN-γ secreted by CD8⁺ T cells in coculture with H2-Q6/GM8909-overexpressed DCs, which were previously treated with DAPT and exposed to irradiated B16F10-OZ cells. (G) mRNA expression of Gm8909 in WT or cKO BMDCs with or without treatment of inhibitor DAPT (n = 3). (H) H2-Kb-SIINFEKL level in WT DCs or DCs overexpressed with GM8909. (I) Confocal fluorescence imaging of DCs for detecting subcellular localization of GM8909 in ER or lysosomes; scale bars: 5 µm. (J) Structure of GM8909 and ClusPro protein–protein docking between GM8909 and B2M. (K) Confocal fluorescence imaging of DCs for detecting subcellular localization of GM8909 with B2M; scale bars: 5 µm. Statistical analysis was performed using two-sided unpaired Student’s t test (B, E, and G); *P < 0.05; **P < 0.01; ***P < 0.001. Data are represented as the mean ± SEM.