Project description:The recurrent chromosome 16 inversion in acute myeloid leukemia generates a fusion gene between CBFB and MYH11, which in turn encodes a chimeric protein CBFβ-SMMHC (core binding factor β-smooth muscle myosin heavy chain). We previously demonstrated that CBFβ-SMMHC needs its C terminal domains for leukemogenesis. In this study, we generated a new Cbfb-MYH11 knock-in mouse model to dissect the role of the multimerization domain at the C terminus of CBFβ-SMMHC. Specifically, we mutated six amino acids in the helices D and E (mDE) of the assembly competent domain, which is important for SMMHC multimerization. We found that the embryos with the mDE mutation (Cbfb+/mDE) did not develop hematopoietic defects seen in embryos with full-length CBFβ-SMMHC (Cbfb+/MYH11). More importantly leukemia development was abolished in the adult Cbfb+/mDE mice even after mutagenesis treatment. In addition, gene expression profile of the hematopoietic cells from the Cbfb+/mDE mice was more similar to that of Cbfb+/+ mice than the Cbfb+/MYH11 mice. Our data suggest that the C terminal multimerization domain is required for the defects in primitive and definitive hematopoiesis caused by CBFβ-SMMHC, and it is also essential for leukemogenesis caused by CBFβ-SMMHC.
Project description:The C-terminus of CBFß-SMMHC, the fusion protein produced by a chromosome 16 inversion in acute myeloid leukemia subtype M4Eo, contains domains for self-mulimerization and transcriptional repression, both of which have been proposed to be important for leukemogenesis by CBFß-SMMHC. To test the role of the fusion protein's C-terminus in vivo, we generated knock-in mice expressing a C-terminally truncated CBFß-SMMHC (CBFß-SMMHCΔC95). Embryos with a single copy of CBFß-SMMHCDC95 were viable and showed no defects in hematopoiesis, while embryos homozygous for the CBFß-SMMHCΔC95 allele had hematopoietic defects and died in mid-gestation, similar to embryos with a single-copy of the full-length CBFß-SMMHCΔC95. To identify gene expression changes induced by CBFß-SMMHCDC95, we compared the gene expression profile in the blood cells of Cbfb+/+, Cbfb+/ΔC95, and CbfbΔC95/ΔC95 embryonic day 12.5 (E12.5) mice. Cbfb+/ΔC95 were mated together to generate Cbfb+/+, Cbfb+/ΔC95, and CbfbΔC95/ΔC95 embryos. Blood from 8-10 E12.5 embryos of the same genotype was pooled, and RNA was isolated, labeled, and hybridized to Affymetrix Genechip mouse microarray (430 2.0) chips. 3 chips were used for each genotype.
Project description:The C-terminus of CBFß-SMMHC, the fusion protein produced by a chromosome 16 inversion in acute myeloid leukemia subtype M4Eo, contains domains for self-mulimerization and transcriptional repression, both of which have been proposed to be important for leukemogenesis by CBFß-SMMHC. To test the role of the fusion protein's C-terminus in vivo, we generated knock-in mice expressing a C-terminally truncated CBFß-SMMHC (CBFß-SMMHCΔC95). Embryos with a single copy of CBFß-SMMHCDC95 were viable and showed no defects in hematopoiesis, while embryos homozygous for the CBFß-SMMHCΔC95 allele had hematopoietic defects and died in mid-gestation, similar to embryos with a single-copy of the full-length CBFß-SMMHCΔC95. To identify gene expression changes induced by CBFß-SMMHCDC95, we compared the gene expression profile in the blood cells of Cbfb+/+, Cbfb+/ΔC95, and CbfbΔC95/ΔC95 embryonic day 12.5 (E12.5) mice.
Project description:A transcriptome study in mouse hematopoietic stem cells was performed using a sensitive SAGE method, in an attempt to detect medium and low abundant transcripts expressed in these cells. Among a total of 31,380 unique transcript, 17,326 (55%) known genes were detected, 14,054 (45%) low-copy transcripts that have no matches to currently known genes. 3,899 (23%) were alternatively spliced transcripts of the known genes and 3,754 (22%) represent anti-sense transcripts from known genes.
Project description:Dominant RUNX1 inhibition has been proposed as a common pathway for CBF-leukemia. CBFb-SMMHC, a fusion protein in human acute myeloid leukemia (AML), dominantly inhibits RUNX1 largely through its RUNX1 high-affinity binding domain (HABD). We generated knock-in mice expressing CBFb-SMMHC with a HABD deletion, CBFb-SMMHCd179-221. These mice developed leukemia highly efficiently, even though hematopoietic defects associated with Runx1-inhibition were partially rescued. To identify changes in gene expression with the deletion of the HABD, we compared the gene expression profile in leukemia samples from mice expressing CBFb-SMMHCd179-221 with those from mice expressing full length CBFb-SMMHC. Spleen cells were isolated from leukemic knock-in mice with full length CBFb-SMMHC at 2 months after ENU treatment and 2 leukemic CBFb-SMMHCd179-221 expressing chimeric mice at 3 weeks after birth. For each genotype, we performed two independent experiments with 4 Affymetrix GeneChip 430 chips.