AML1-FOG2 Fusion Protein in Myelodysplasia.

Core binding factor (CBF) participates in specification of the hematopoietic stem cell and functions as a critical regulator of hematopoiesis. Translocation or point mutation of AML1, which encodes the DNA-binding subunit of CBF, plays a central role in the pathogenesis of acute myeloid leukemia and myelodysplasia. We characterized the translocation t(X;21)(p22.3;q22.1) in a patient with myelodysplasia that fuses AML1 to the novel partner gene Friend of GATA-2 (FOG2). The reciprocal gene fusions AML1-FOG2 and FOG2-AML1 are both expressed. AML1-FOG2, which fuses the DNA-binding domain of AML1 to most of FOG2, represses transcription from the promoter of a hematopoietic target of AML1. AML1-FOG2 retains a motif that recruits the corepressor C-terminal binding protein (CtBP) and both proteins associate in a protein complex. These results suggest a role for CtBP in AML1-FOG2 transcriptional repression and implicate coordinated disruption of the AML1 and GATA developmental programs in the pathogenesis of myelodysplasia.