Project description:CHAF1B is the p60 subunit of the chromatin assembly factor (CAF1) complex, which is responsible for assembly of H3.1/H4 heterodimers at the replication fork during S phase. Here we report that CHAF1B is required for normal hematopoiesis while its overexpression promotes leukemia. CHAF1B has a pro-leukemia effect by binding chromatin at discrete sites and interfering with occupancy of transcription factors that promote myeloid differentiation, such as CEBPA. Reducing Chaf1b activity by either heterozygous deletion or overexpression of a CAF1 dominant negative allele was sufficient to suppress leukemogenesis in vivo without impairing normal hematopoiesis.
Project description:This SuperSeries is composed of the following subset Series: GSE16432: MSI2 regulates hematopoiesis and accelerates leukemogenesis GSE22773: Musashi 2 regulates normal hematopoiesis and accelerates leukemogenesis (LK and MS12-inducible) GSE22774: Musashi 2 regulates normal hematopoiesis and accelerates leukemogenesis (LSK and LK) GSE22775: Musashi 2 regulates normal hematopoiesis and accelerates leukemogenesis (Leukemia cell lines) Refer to individual Series
Project description:It is not clear whether disrupted age-specific hematopoiesis contributes to the complex manifestations in leukemia patients who carry identical mutations, particularly in pediatric and adult patients with similar clinical characteristics. By studying a dual-age-specific mouse model, we demonstrate: 1) loss of Pten during the fetal-to-adult hematopoiesis switch (HSC switch) causes sustained fetal hematopoiesis, resulting in death in juvenile leukemia; 2) myeloid-biased hematopoiesis in juvenile mice is associated with the sustained fetal properties of hematopoietic stem cells (HSCs); 3) the age specificity of juvenile myelomonocytic leukemia (JMML) depends on the dosage of Pten and Nf1; 4) single-allelic Pten deletion during the HSC switch causes constitutive activation of mitogen-activated protein kinase (MAPK) in juvenile mice with Nf1 loss of heterozygosity (LOH); and 5) Nf1 LOH causes monocytosis in juvenile mice with Pten haploinsufficiency but does not cause lethality until adulthood. Our data suggest that one copy of Pten is sufficient to maintain an intact negative feedback loop of the Akt pathway and HSC function in reconstitution, despite MAPK being constitutively activated in juvenile mice with Pten+/DNf1LOH. However, two copies of Pten are required to maintain the integrity of the MAPK pathway in juvenile mice with Nf1 haploinsufficiency. Our data indicate that previous investigations of Pten function in wild type mice may not reflect the impact of Pten loss in mice with Nf1 mutations or other genetic defects. We provide a proof-of-concept that disassociated age-specific hematopoiesis contributes to leukemogenesis and pediatric demise.
Project description:Purpose: This study was conducted to identify novel genes with importance to the biology of adult acute myelogenous leukemia (AML). Conclusions: NF1 null states are present in 7/95=7% of adult AML and delineate a disease subset that could be preferentially targeted by Ras or mTOR-directed therapeutics.