U2af1, also known as U2 small nuclear RNA auxiliary factor 1, is a multifunctional protein belonging to the SR family of splicing factors. It plays a crucial role in the regulation of RNA splicing during eukaryotic gene expression, being involved in the removal of introns from mRNAs and exon-exon binding. The U2AF1/U2AF2 heterodimer is essential for 3' splice site (3'SS) definition [1].

Using a conditional U2af1 knockout allele in mice, deletion of U2af1 led to profound hematopoiesis defects. These included pancytopenia, ablation of hematopoietic stem/progenitor cells (HSPC) resulting in bone marrow failure and early lethality. U2af1 deletion also impaired HSPC function and repopulation capacity, increased DNA damage, and reduced survival in hematopoietic progenitors. RNA sequencing analysis showed significant alterations in gene expression related to HSC maintenance, cell proliferation, and DNA damage response-related pathways in U2af1-deficient HSPC [2].

In conclusion, U2af1 is essential for the survival and function of hematopoietic stem/progenitor cells in normal hematopoiesis. The conditional knockout mouse model of U2af1 has provided valuable insights into the role of U2af1 in hematopoiesis, which is important for developing therapeutic approaches for U2AF1 mutant-induced hematologic malignancies [2].