Anchored screening identifies transcription factor blueprints underlying dendritic cell diversity and subset-specific anti-tumor immunity [mouse bulk RNA-seq]

Transcription factor cooperation is essential for specifying the heterogeneous dendritic cell (DC) lineages that orchestrate adaptive immunity, yet how it drives subset diversification remains poorly understood. Here, we employed a sequential anchored screen of 70 transcription factors using direct cellular reprogramming to identify regulators that specify type 2 conventional DCs (cDC2s) and plasmacytoid DCs (pDCs). We identified PU.1, IRF4, and PRDM1 as inducers of a pro-inflammatory cDC2B-like fate and SPIB, IRF8, and IKZF2 as mediators of an immature lymphoid DC program. Transcriptomic profiling linked these triads to lineage-specific signatures and demonstrated their requirement for subset identity. Mechanistically, lineage divergence was driven by chromatin co-engagement at subset-specific sites early in reprogramming. Functionally, reprogrammed DCs employed distinct immune mechanisms to elicit orthogonal anti-tumor responses in different tumor models. Collectively, our findings uncover transcriptional circuits that control DC diversification and pave the way to generate patient-tailored DC subsets for cancer immunotherapy. Overall design: PIB, PIP and SII-transduced fibroblasts were FACS sorted for CD45 positive, reporter positive (tdTomato+ for all and YFP+ for SII) or reporter and CD45 positive at day 3 (d3), day 6 (d6) and day9 (d9) and profiled by bulk RNA sequencing. Untransduced MEFs, freshly isolated splenic cDC1s (CD11c+ MHCII+ XCR1+ CD11b-), cDC2s (CD11c+ MHCII+ CD11b+ XCR1-), and pDCs (CD11c+ Siglec-H+ B220+ BST2+) were included as controls.