Subject(s)
CCAAT-Enhancer-Binding Protein-beta/physiology , DNA-Binding Proteins/analysis , Leukemia, Myeloid, Acute/etiology , Transcription Factors/analysis , Aged , Animals , DNA-Binding Proteins/genetics , Disease Models, Animal , ErbB Receptors/physiology , Humans , MDS1 and EVI1 Complex Locus Protein , Mice , Proto-Oncogenes/genetics , Transcription Factors/geneticsABSTRACT
Ecotropic viral integration site 1 (Evi1) is one of the master regulators in the development of acute myeloid leukemia (AML) and myelodysplastic syndrome. High expression of Evi1 is found in 10% of patients with AML and indicates a poor outcome. Several recent studies have indicated that Evi1 requires collaborative factors to induce AML. Therefore, the search for candidate factors that collaborate with Evi1 in leukemogenesis is one of the key issues in uncovering the mechanism of Evi1-related leukemia. Previously, we succeeded in making a mouse model of Evi1-related leukemia using a bone marrow transplantation (BMT) system. In the Evi1-induced leukemic cells, we identified frequent retroviral integrations near the CCAAT/enhancer-binding protein ß (C/EBPß) gene and overexpression of its protein. These findings imply that C/EBPß is a candidate gene that collaborates with Evi1 in leukemogenesis. Cotransduction of Evi1 and the shortest isoform of C/EBPß, liver inhibitory protein (LIP), induced AML with short latencies in a mouse BMT model. Overexpression of LIP alone also induced AML with longer latencies. However, excision of all 3 isoforms of C/EBPß (LAP*/LAP/LIP) did not inhibit the development of Evi1-induced leukemia. Therefore, isoform-specific intervention that targets LIP is required when we consider C/EBPß as a therapeutic target.
Subject(s)
Bone Marrow Transplantation , CCAAT-Enhancer-Binding Protein-beta/physiology , Cell Transformation, Neoplastic/genetics , DNA-Binding Proteins/physiology , Leukemia, Myeloid, Acute/genetics , Proto-Oncogenes/physiology , Transcription Factors/physiology , Animals , Bone Marrow Transplantation/adverse effects , Bone Marrow Transplantation/pathology , CCAAT-Enhancer-Binding Protein-beta/genetics , CCAAT-Enhancer-Binding Protein-beta/metabolism , Cells, Cultured , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Disease Models, Animal , Gene Expression Regulation, Leukemic , Humans , Leukemia, Myeloid, Acute/etiology , Leukemia, Myeloid, Acute/pathology , MDS1 and EVI1 Complex Locus Protein , Mice , Mice, Inbred C57BL , Mice, Knockout , Models, Biological , Protein Isoforms/genetics , Protein Isoforms/metabolism , Protein Isoforms/physiology , Proto-Oncogenes/genetics , Transcription Factors/genetics , Transcription Factors/metabolismABSTRACT
Ecotropic viral integration site 1 (Evi1), a transcription factor of the SET/PR domain protein family, is essential for the maintenance of hematopoietic stem cells (HSCs) in mice and is overexpressed in several myeloid malignancies. Here, we generate reporter mice in which an internal ribosome entry site (IRES)-GFP cassette is knocked-in to the Evi1 locus. Using these mice, we find that Evi1 is predominantly expressed in long-term HSCs (LT-HSCs) in adult bone marrow, and in the hematopoietic stem/progenitor fraction in the aorta-gonad-mesonephros, placenta, and fetal liver of embryos. In both fetal and adult hematopoietic systems, Evi1 expression marks cells with long-term multilineage repopulating activity. When combined with conventional HSC surface markers, sorting according to Evi1 expression markedly enhances purification of cells with HSC activity. Evi1 heterozygosity leads to marked impairment of the self-renewal capacity of LT-HSCs, whereas overexpression of Evi1 suppresses differentiation and boosts self-renewal activity. Reintroduction of Evi1, but not Mds1-Evi1, rescues the HSC defects caused by Evi1 heterozygosity. Thus, in addition to documenting a specific relationship between Evi1 expression and HSC self-renewal activity, these findings highlight the utility of Evi1-IRES-GFP reporter mice for the identification and sorting of functional HSCs.
