Project description:Mutations of RUNX1 are detected in patients with myelodysplastic syndrome (MDS). In particular, C-terminal truncation mutations lack a transcription regulatory domain and have increased DNA binding through the runt homology domain (RHD). The expression of the RHD, RUNX1(41-214), in mouse hematopoietic cells induced progression to MDS and acute myeloid leukemia (AML). Analysis of pre-myelodysplastic animals revealed expansion of c-Kit+Sca-1+Lin- (KSL) cells and skewed differentiation to myeloid at the expense of the lymphoid lineage. These abnormalities correlate with the phenotype of Runx1-deficient animals, as expected given the reported dominant-negative role of C-terminal mutations over the full-length RUNX1. However, MDS is not observed in Runx1-deficient animals. Gene expression profiling revealed that RUNX1(41-214) KSLs have an overlapping yet distinct gene expression profile from Runx1-deficient animals. Moreover, an unexpected parallel was observed between the hematopoietic phenotype of RUNX1(41-214) and aged animals. Genes deregulated in RUNX1(41-214), but not in Runx1-deficient animals, were inversely correlated with the aging gene signature of hematopoietic stem cells (HSC), suggesting that disruption of the expression of genes related to normal aging by RUNX1 mutations contributes to development of MDS. The data presented here provide insights into the mechanisms of development of MDS in HSCs by C-terminal mutations of RUNX1. Gene expression analysis were performed on c-Kit+/Sca-1+/Lin-/IL7Ra- (KSL) cells sorted from RUNX1(41-214)-expressing and Runx1-knockout (Runx1floxed/floxed MxCre+/-) and control mice (Runx1floxed/floxedMxCre-/-).
Project description:Mutations of RUNX1 are detected in patients with myelodysplastic syndrome (MDS). In particular, C-terminal truncation mutations lack a transcription regulatory domain and have increased DNA binding through the runt homology domain (RHD). The expression of the RHD, RUNX1(41-214), in mouse hematopoietic cells induced progression to MDS and acute myeloid leukemia (AML). Analysis of pre-myelodysplastic animals revealed expansion of c-Kit+Sca-1+Lin- (KSL) cells and skewed differentiation to myeloid at the expense of the lymphoid lineage. These abnormalities correlate with the phenotype of Runx1-deficient animals, as expected given the reported dominant-negative role of C-terminal mutations over the full-length RUNX1. However, MDS is not observed in Runx1-deficient animals. Gene expression profiling revealed that RUNX1(41-214) KSLs have an overlapping yet distinct gene expression profile from Runx1-deficient animals. Moreover, an unexpected parallel was observed between the hematopoietic phenotype of RUNX1(41-214) and aged animals. Genes deregulated in RUNX1(41-214), but not in Runx1-deficient animals, were inversely correlated with the aging gene signature of hematopoietic stem cells (HSC), suggesting that disruption of the expression of genes related to normal aging by RUNX1 mutations contributes to development of MDS. The data presented here provide insights into the mechanisms of development of MDS in HSCs by C-terminal mutations of RUNX1.
Project description:The RUNX genes encode for transcription factors involved in development and human disease. RUNX1 and RUNX3 are frequently associated with leukemias, yet the basis for their involvement in leukemogenesis is not fully understood. Here we show that Runx1;Runx3 double knockout (DKO) mice exhibited lethal phenotypes due to bone marrow failure and myeloproliferative disorder. These contradictory clinical manifestations are reminiscent of human inherited bone marrow failure syndromes like Fanconi anemia (FA), caused by defective DNA repair. Indeed, Runx1;Runx3 DKO cells showed mitomycin C hypersensitivity, due to impairment of monoubiquitinated-FANCD2 recruitment to DNA damage foci, although FANCD2 monoubiquitination in the FA pathway was unaffected. RUNX1 and RUNX3 interact with FANCD2 independent of CBFM-NM-2, suggesting non-transcriptional role for RUNX in DNA repair. These findings suggest that RUNX dysfunction causes DNA repair defect, besides transcriptional misregulation, and promotes development of leukemias and other cancers. 6 mice were analyzed in this study. 3 Runx1;Runx3 double knockout cKit+Sca1+Lin- hematopoietic stem/progenitor cells were compared with their wild type littermate controls. RNA was isolated from 3 independent Runx1;Runx3 WT KSL samples, each pooled from 3 Runx1;Runx3 WT mice, and 3 independent Runx1;Runx3 DKO KSL samples, using the RNeasy Micro Kit (QIAgen). RNA integrity and quantity was assessed using the Agilent 2000 Bioanalyzer system. 3 M-NM-<g to 5 M-NM-<g RNA was processed using WT-Ovation Pico RNA Amplification System (NuGEN) paired with the WT-Ovation Exon Module and FL-Ovation cDNA Biotin Module (NuGEN). A detailed protocol in the userM-bM-^@M-^Ys guide kit was used without modification. cDNA were prepared for hybridization on GeneChip Mouse Gene 1.0 ST Arrays (Affymetrix) according to the instructions in GeneChip Hybridization Wash and Stain Kit for ST arrays (Affymetrix). Microarray hybridization, scanning and preliminary MAS 5.0 normalizations were completed at the A*STAR Biopolis Shared Facilities (BSF).
Project description:Cellular binary fate decisions require the progeny to silence genes associated with the alternative fate. The major subsets of alpha:beta T cells have been extensively studied as a model system for fate decisions. While the transcription factor RUNX3 is required for the initiation of Cd4 silencing in CD8 T cell progenitors, it is not required to maintain the silencing of Cd4 and other helper T lineage genes. The other runt domain containing protein, RUNX1, silences Cd4 in an earlier T cell progenitor, but this silencing is reversed whereas the gene silencing after RUNX3 expression is not reverse. Therefore, we hypothesized that RUNX3 and not RUNX1 recruits other factors that maintains the silencing of helper T lineage genes in CD8 T cells. To this end, we performed a proteomics screen of RUNX1 and RUNX3 to determine candidate silencing factors.
Project description:We discovered that expression of the transcription factor RUNX1 is enriched in the fetal ovary in various vertebrate species. In the mouse, RUNX1 marks the supporting cell lineage and becomes granulosa cell-specific as the gonads differentiate. To understand the function of Runx1 during fetal development of the ovary, we ablated Runx1 specifically in the somatic cell lineage of the fetal ovaries using Sf1-Cre . We compared ovarian differentiation in wild type, Runx1 and Foxl2 single knockouts, and Runx1/Foxl2 double knockout ovaries. Transcriptome comparisons of newborn ovaries revealed that loss of Runx1 or Foxl2 affected a similar set of genes: 41% of the genes affected by the loss of Runx1 were also changed by the loss of Foxl2. Despite these transcriptomic changes, granulosa cell identity was maintained during fetal life in both Runx1 or Foxl2 single knockout ovaries. However, the combined loss of Runx1/Foxl2 resulted in masculinization of the ovaries during fetal life. To further characterize the impacts of the combined loss of Runx1 and Foxl2 on ovarian differentiation, we compared the transcriptome of Runx1/Foxl2 DKO newborn ovaries with the transcriptomes of control, Runx1, or Foxl2 single KO ovaries.
Project description:RUNX1 transcription factor (TF) is a key regulator of megakaryocytic development and when mutated is associated with familial platelet disorder and predisposition to acute myeloid leukemia (FPD-AML). We used mice lacking Runx1 specifically in megakaryocytes (MKs) to characterize the Runx1-mediated transcriptional program during advanced stages of MK differentiation. Gene expression and chromatin-immunoprecipitation-sequencing (ChIP-seq) of Runx1 and p300 identified functional Runx1-bound MK enhancers. Runx1/p300 co-bound regions showed significant enrichment in genes important for MK and platelet homeostasis. Runx1-bound regions were highly enriched in RUNX and ETS motifs and to a lesser extent in GATA motif. The data provides the first example of genome-wide Runx1/p300 occupancy in maturating FL-MK, unravels the Runx1-regulated program controlling MK maturation in vivo and identifies its bona fide regulated genes. It advances our understanding of the molecular events that upon mutations in RUNX1 lead to the predisposition to familial platelet disorders and FPD-AML. Gene expression profiles of mature megakaryocytes taken from fetal livers of megakaryocyte-specific Runx1 knockout mice, using Runx1F/F/Pf4-Cre mice versus control (WT) mice.