U2AF1 mutation causes an oxidative stress and DNA repair defect in hematopoietic and leukemic cells.

U2AF1 is a core component of spliceosome and controls cell-fate specific alternative splicing. U2AF1 mutations have been frequently identified in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) patients, and mutations in U2AF1 are associated with poor prognosis in hematopoietic malignant diseases. Here, by forced expression of mutant U2AF1 (U2AF1 S34F) in hematopoietic and leukemic cell lines, we find that U2AF1 S34F causes increased reactive oxygen species (ROS) production. In hematopoietic cell line, a defect in mitochondrial function and DNA damage response deficiency are found in U2AF1 S34F expressing 32D cells. In leukemic cell line Molm13 cells, U2AF1 mutation leads to resistance to DNA damaging agents. Accumulation of DNA damage is also found in U2AF1 S34F expressing leukemic cells when treated with DNA damage agent. Finally, in our established hematopoietic-specific U2af1 S34F knock-in mice model, U2AF1 mutation leads to the development of myelodysplastic/myeloproliferative neoplasm (MDS/MPN) and causes DNA damage accumulation in hematopoietic cells. Our study provides evidence that U2AF1 mutation causes DNA damage response deficiency and DNA damage accumulation in hematopoietic cells, and suggests that mutant U2AF1 induced higher ROS production, resistance to DNA damaging agents and increased genomic instability may contribute to poor prognosis of AML patients with U2AF1 mutations.