The development of dendritic cells (DCs), including antigen-presenting conventional DCs (cDCs) and cytokine-producing plasmacytoid DCs (pDCs), is controlled by the growth factor Flt3 ligand (Flt3L) and its receptor Flt3. We genetically dissected Flt3L-driven DC differentiation using CRISPR-Cas9–based screening. Genome-wide screening identified multiple regulators of DC differentiation including subunits of TSC and GATOR1 complexes, which restricted progenitor growth but enabled DC differentiation by inhibiting mTOR signaling. An orthogonal screen identified the transcriptional repressor Trim33 (TIF-1γ) as a regulator of DC differentiation. Conditional targeting in vivo revealed an essential role of Trim33 in the development of all DCs, but not of monocytes or granulocytes. In particular, deletion of Trim33 caused rapid loss of DC progenitors, pDCs, and the cross-presenting cDC1 subset. Trim33-deficient Flt3⁺ progenitors up-regulated pro-inflammatory and macrophage-specific genes but failed to induce the DC differentiation program. Collectively, these data elucidate mechanisms that control Flt3L-driven differentiation of the entire DC lineage and identify Trim33 as its essential regulator.

中文翻译：

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全基因组筛选确定 Trim33 是树突状细胞分化的重要调节因子

树突状细胞（DC）的发育，包括抗原呈递的常规DC（cDC）和产生细胞因子的浆细胞样DC（pDC），由生长因子Flt3配体（Flt3L）及其受体Flt3控制。我们使用基于 CRISPR-Cas9 的筛选对 Flt3L 驱动的 DC 分化进行了基因剖析。全基因组筛选确定了 DC 分化的多个调节因子，包括 TSC 和 GATOR1 复合物的亚基，它们限制祖细胞生长，但通过抑制 mTOR 信号传导使 DC 分化。正交筛选鉴定出转录抑制因子 Trim33 (TIF-1γ) 是 DC 分化的调节因子。体内条件靶向揭示了 Trim33 在所有 DC 发育中的重要作用，但在单核细胞或粒细胞发育中则不然。特别是，Trim33 的缺失导致 DC 祖细胞、pDC 和交叉呈递的 cDC1 子集快速丢失。 Trim33 缺陷的 Flt3 ⁺祖细胞上调促炎和巨噬细胞特异性基因，但未能诱导 DC 分化程序。总的来说，这些数据阐明了控制 Flt3L 驱动的整个 DC 谱系分化的机制，并将 Trim33 确定为其重要的调节因子。