Hematopoiesis is a continuous process of blood cell production driven by hematopoietic stem and progenitor cells (HSPCs) in the bone marrow. Proliferation and differentiation of HSPCs are regulated by complex transcriptional networks. In order to identify transcription factors with key roles in HSPC-mediated hematopoietic reconstitution, we developed an efficient and robust CRISPR/Cas9-based in vivo genetic screen. Using this experimental system, we identified the TFDP1 transcription factor to be essential for HSPC proliferation and post-transplant hematopoiesis. We further discovered that E2F4, an E2F transcription factor, serves as a binding partner of TFDP1 and is required for HSPC proliferation. Deletion of TFDP1 caused downregulation of genes associated with the cell cycle, with around 50% of these genes being identified as direct targets of TFDP1 and E2F4. Thus, our study expands the transcriptional network governing hematopoietic development through an in vivo CRISPR/Cas9-based genetic screen and identifies TFDP1/E2F4 as positive regulators of cell cycle genes in HSPCs.

造血是由骨髓中的造血干细胞和祖细胞（HSPC）驱动的连续的血细胞生成过程。 HSPC 的增殖和分化受到复杂的转录网络的调节。为了鉴定在 HSPC 介导的造血重建中起关键作用的转录因子，我们开发了一种高效且强大的基于 CRISPR/Cas9 的体内遗传筛选。使用该实验系统，我们确定了 TFDP1 转录因子对于 HSPC 增殖和移植后造血至关重要。我们进一步发现 E2F4（一种 E2F 转录因子）作为 TFDP1 的结合伴侣，是 HSPC 增殖所必需的。 TFDP1 的缺失导致与细胞周期相关的基因下调，其中约 50% 的基因被确定为 TFDP1 和 E2F4 的直接靶标。因此，我们的研究通过基于 CRISPR/Cas9 的体内遗传筛选扩展了控制造血发育的转录网络，并将 TFDP1/E2F4 鉴定为 HSPC 中细胞周期基因的正调节因子。