ABSTRACT: Analysis of differential gene expression in Cebpa-positive and Cebpa-negative hematopoietic stem cells using a Cebpa-Cre EYFP reporter mouse model
Project description:C/EBPalpha is a transcription factor critically involved in myeloid development and indispensable for formation of granulocytes. To track the cellular fate of stem and progenitor (LSK) cells, which express C/EBPalpha, we developed a mouse model expressing Cre recombinase from the Cebpa promoter and an inducible EYFP allele. We show that Cebpa/EYFP+ cells represent a significant subset of LSK cells, which predominantly give rise to myeloid cells in steady state hematopoiesis. C/EBPalpha induced a robust myeloid gene expression signature and downregulated E2A-induced regulators of early lymphoid development. In addition, Cebpa/EYFP+ cells comprise a fraction of early thymic progenitors (ETP) with robust myeloid potential. However, Cebpa/EYFP+ LSK and ETP cells retained the ability to develop into erythroid and T-lymphoid lineages, respectively. These findings support an instructive, but argue against a lineage restrictive role of C/EBPalpha in multipotent hematopoietic and thymic progenitors. We performed global gene expression profiling of double-sorted Cebpa/EYFP+ and Cebpa/EYFP- LSK cells of pooled Cebpa Cre/wt R26 EYFP reporter mice to identify differentially regulated genes in Cebpa+ versus Cebpa- LSK cells. RNA was isolated from three biological replicates of Cebpa/EYFP+ LSK cells and two biological replicates of Cebpa/EYFP- LSK cells. To determine if the identified genes were truly dependent on Cebpa expression, we also performed global gene expression profilling of Cebpa/EYFP+ and Cebpa/EYFP- fetal liver LSK cells of Cebpa Cre/fl R26 EYFP mice. Induction of Cebpa/Cre expression in these mice leads to Cre-mediated recombination of the floxed wt Cebpa allele resulting in a complete Cebpa knock-out. In this case, RNA was isolated from two biological replicates of either Cebpa/EYFP+ and Cebpa/EYFP- LSK cells. In addition, we included one biological replicate of Cebpa/EYFP+ and Cebpa/EYFP- fetal liver LSK cells of Cebpa Cre/wt R26 EYFP mice to determine the correlation of differentially regulated genes in bone marrow and fetal liver LSK cells.
Project description:ER71 mutant embryos are nonviable and lack hematopoietic and endothelial lineages. To further define the functional role for ER71 in cell lineage decisions, we generated genetically modified mouse models. We engineered an ER71-EYFP transgenic mouse model by fusing the 3.9 kb ER71 promoter to the EYFP reporter gene. Using FACS and transcriptional profiling, we examined the EYFP+ populations of cells in ER71 mutant and wildtype littermates. In the absence of ER71, we observed an increase in the number of EYFP expressing cells, increased expression of the cardiac molecular program and decreased expression of the hemato-endothelial program compared to the wildtype littermate controls. We have also generated a novel ER71-Cre transgenic mouse model using the same 3.9 kb ER71 promoter. Genetic fate mapping studies revealed that the ER71 expressing cells daughter hematopoietic and endothelial lineages in the wildtype background. In the absence of ER71, these cell populations contributed to alternative mesodermal lineages including the cardiac lineage. To extend these analyses, we used an inducible ES/EB system and observed that ER71 overexpression repressed cardiogenesis. Together, these studies identify ER71 as a critical regulator of mesodermal fate decisions, acting to specify the hematopoietic and endothelial lineages at the expense of cardiac lineages. This enhances our understanding of the mechanisms that govern mesodermal fate decisions early during embryogenesis. 12samples were analyzed, including triplicates of WT; EYFP positive, WT EYFP negative, ER71 MT; EYFP positive and ER71 MT; EYFP negative cells
Project description:MiRNAs have the potential to regulate cellular differentiation programs. However, miRNA-deficiency in primary hematopoietic stem cells (HSCs) results in HSC depletion in mice, leaving the question of whether miRNAs play a role in early-lineage decisions unanswered. To address this issue, we deleted Dicer1, which encodes an essential RNaseIII enzyme for miRNA biogenesis, in murine CCAAT/enhancer-binding protein alpha (C/EBPA)-positive myeloid-committed progenitors in vivo. In contrast to the results in HSCs, we found that miRNA depletion affected neither the number of myeloid progenitors nor the percentage of C/EBPA-positive progenitor cells. Analysis of gene-expression profiles from wild type and Dicer1-deficient granulocyte-macrophage progenitors (GMPs) revealed that 20 miRNA families were active in GMPs. Of the derepressed miRNA targets in Dicer1-null GMPs, 27% are normally exclusively expressed in HSCs or are specific for multi-potent progenitors and erythropoiesis, indicating an altered gene-expression landscape. Dicer1-deficient GMPs were defective in myeloid development in vitro and exhibited an increased replating capacity, indicating a regained self-renewal potential of these cells. In mice, Dicer1 deletion blocked monocytic differentiation, depleted macrophages and caused myeloid dysplasia with morphological features of Pelger-Huët anomaly. These results provide evidence for a miRNA-controlled switch for a cellular program of self-renewal and expansion towards myeloid differentiation in GMPs. To generate Cebpa-Cre;R26-LSL-Eyfp;Dicer1wt/fl/Dicer1fl/fl mice, we crossed mice that contain floxed Dicer1 alleles (Dicer1fl) with Cebpa-Cre;R26-LSL-Eyfp reporter mice 2. Fetal livers were obtained on embryonic day (E) 13.5. Routine genotyping of Dicer1; Cebpa-Cre;R26-LSL-Eyfp mice was performed by PCR assays of DNA from tail or toe biopsies. For transplantation, 6 to 8-week-old recipient mice (C57Bl/6, Jackson Laboratories) were irradiated (8.5 Gy) and tail-vein injected with fetal liver single-cell suspensions. Typically, cells from each fetal liver were transplanted into two recipient mice. Hematopoietic tissues were analyzed 6-10 weeks post transplantation. EYFP positive GMPs from the bone marrow of Dicer wt control (n=3), Dicer -/wt (n=3 and Dicer fl/fl (n=3) were sorted and analyzed for gene expression profiles.
Project description:C/EBPalpha is a transcription factor critically involved in myeloid development and indispensable for formation of granulocytes. To track the cellular fate of stem and progenitor (LSK) cells, which express C/EBPalpha, we developed a mouse model expressing Cre recombinase from the Cebpa promoter and an inducible EYFP allele. We show that Cebpa/EYFP+ cells represent a significant subset of LSK cells, which predominantly give rise to myeloid cells in steady state hematopoiesis. C/EBPalpha induced a robust myeloid gene expression signature and downregulated E2A-induced regulators of early lymphoid development. In addition, Cebpa/EYFP+ cells comprise a fraction of early thymic progenitors (ETP) with robust myeloid potential. However, Cebpa/EYFP+ LSK and ETP cells retained the ability to develop into erythroid and T-lymphoid lineages, respectively. These findings support an instructive, but argue against a lineage restrictive role of C/EBPalpha in multipotent hematopoietic and thymic progenitors.
Project description:ER71 mutant embryos are nonviable and lack hematopoietic and endothelial lineages. To further define the functional role for ER71 in cell lineage decisions, we generated genetically modified mouse models. We engineered an ER71-EYFP transgenic mouse model by fusing the 3.9 kb ER71 promoter to the EYFP reporter gene. Using FACS and transcriptional profiling, we examined the EYFP+ populations of cells in ER71 mutant and wildtype littermates. In the absence of ER71, we observed an increase in the number of EYFP expressing cells, increased expression of the cardiac molecular program and decreased expression of the hemato-endothelial program compared to the wildtype littermate controls. We have also generated a novel ER71-Cre transgenic mouse model using the same 3.9 kb ER71 promoter. Genetic fate mapping studies revealed that the ER71 expressing cells daughter hematopoietic and endothelial lineages in the wildtype background. In the absence of ER71, these cell populations contributed to alternative mesodermal lineages including the cardiac lineage. To extend these analyses, we used an inducible ES/EB system and observed that ER71 overexpression repressed cardiogenesis. Together, these studies identify ER71 as a critical regulator of mesodermal fate decisions, acting to specify the hematopoietic and endothelial lineages at the expense of cardiac lineages. This enhances our understanding of the mechanisms that govern mesodermal fate decisions early during embryogenesis.
Project description:Fibroblastic reticular cells (FRCs) (CD45- Ter119-MADCAM1- CD21/35- CD31- PDPN-) from skin draining lymph nodes of Grem1-Cre-ERT2.cki; Rosa26-LSL-EYFP mice were sorted and subjected to bulk RNA-seq of Grem1 reporter + and Grem1 reporter - cells.
Project description:We analyzed the effect of Calr deficiency on Mac1 and Gr1 positive bone marrow cells using hematopoietic cell specific Calr knockout (Mx-cre;Calrf/-) mice and control (Mx-cre;Calr+/+) mice.
Project description:Cx3cr1CreER-Eyfp/wt mice contain a subset of microglia lacking Cre and EYFP expression. These microglial escape Cre-mediated recombination and gain a repopulation advantage following Cre-driven DTA-mediated microglial depletion.
Project description:Transcriptome analysis of Casz1 was performed using litters of postnatal day 2 retinas from crosses between Casz1Flox/Flox; R26-Stop-EYFP and Casz1Flox/Flox; IKCre-A; R26-Stop-EYFP. The IK-A Cre driver is described in Tarchini et al., Dev Dyn 241(12):1973-85. EYFP marks Cre expressing (and therefore cKO) cells. Cells were incubated for 30 min in RGM serum-free medium described in Cayouette et al., Neuron 40(5):897, supplemented with Hoechst 33342 (Invitrogen), and 4N cells were sorted using a MOFLO cytometer (Beckman) based on Hoechst, GFP expression, and propidium iodide exclusion.
Project description:The clinical impact of aberrant CEBPA promoter methylation (PM) in AML is controversial discussed. The aim of this study was to clarify the significance of aberrant CEBPA PM with regard to clinical features in a cohort of 572 de novo AML with wildtype CEBPA and normal karyotype. The distal promoter was methylated in 54/572 cases (9.41%) whereas proximal PM was never detected. Methylation of the core promoter was detected in only 8 of 326 cases (2.45%) and thus seems to be a rare event in AML. There was no correlation between CEBPA distal PM, age, sex, white blood cell (WBC) count or Hb levels at diagnosis. We also were not able to detect a significant correlation between the presence of CEBPA distal PM and molecular mutations such as FLT3-ITD, NPM1, AML1, MLL-PTD and IDH1. Solely the frequency of IDH2R140 mutations was significantly reduced in CEBPA distal PM positive compared to CEBPA distal PM negative cases (p=0.01). Furthermore, analysis of CEBPA mRNA expression level revealed no difference between CEBPA distal PM positive and CEBPA distal PM negative cases, suggesting that CEBPA distal PM has no influence on CEBPA expression. CEBPA distal PM did not show impact on overall survival (OS), event free survival (EFS) or incidence of relapse. Also when other mutations were taken into regard no prognostic impact of CEBPA distal PM could be shown. In contrast, a distinct expression profile of CEBPA distal PM positive cases compared to CEBPA mutated and CEBPA distal PM negative cases was observed. In addition, a significantly higher frequency of CEBPA distal PM was detected in RUNX1-RUNX1T1 positive AML compared to the CEBPA witdtype cases. We conclude that the presence of aberrant CEBPA PM has no clinical relevance and is therefore a negligible prognostic marker in de novo AML with normal karyotype.