THE TRANSCRIPTION FACTOR C/EBPG IS RESPONSIBLE FOR RAPID PRODUCTION OF NEUTROPHILS DURING EMERGENCY GRANULOPOIESIS
(Abstract release date: 05/19/16)
EHA Library. Kardosova M. 06/09/16; 132675; E1126
Ms. Miroslava Kardosova
Contributions
Contributions
Abstract
Abstract: E1126
Type: Eposter Presentation
Background
CCAAT/enhancer binding protein γ (C/EBPγ) is a member of the C/EBP family of myeloid transcription factors, which are known as master regulators of hematopoiesis. Recently, it has been shown that increased C/EBPγ levels contribute to the block of neutrophilic differentiation in acute myeloid leukemias characterized by C/EBPα hypermethylation. Hovewer, the function of C/EBPγ in normal and stress-induced hematopoiesis remains largely unknown.
Aims
In this study we investigate the role of C/EBPγ in hematopoiesis both in steady-state and under stress conditions.
Methods
We generated a C/EBPγ conditional knockout murine model, which allows tissue and time specific excision of C/EBPγ. These mice were crossed to Vav-1Cre deleter strain to excise C/EBPγ specifically in the hematopoietic system from early embryonic stages. We employed C/EBPγ f/f Vav-1Cre- and C/EBPγ f/f Vav-1Cre+ mice, refered here as wt and C/EBPγ ko respectively. First, frequency of distinct hematopoietic lineages in bone marrow, spleen, and blood of C/EBPγ ko mice was determined by flow cytometry. Next, to elucidate whether C/EBPγ is necessary for stress induced granulopoiesis, in vivo administration of different stimuli, including lipopolysacharide (LPS), granulocyte colony-stimulating factor (G-CSF) and Candida albicans, was used to model bacteria- or candidemia-induced emergency granulopoiesis. Mice were sacrified and examined 24 hours after infection since we focused on early phases of granulopoiesis. Differential cell counting and flow cytometric analysis were performed to assess whether C/EBPγ is involved in demand-accelerated neutrophilic production.
Results
Mice lacking C/EBPγ within the hematopoietic system presented partially reduced levels of blood neutrophils (wt 1.438x106/ml -/+ 0.114 vs CEBPγ ko 0.988x106/ml -/+ 0.078, p=0.0021), although this reduction did not result in any signs of sickness. Analysis of other cell populations, including progenitors and hematopoietic stem cells, did not reveal further differences between wt and C/EBPγ ko mice. These data suggest that hematopoietic-specific genetic ablation of C/EBPγ is not critical for steady-state hematopoiesis. Since C/EBPγ forms heterodimers with another C/EBP member, C/EBPβ, we determined whether C/EBPγ can modulate the function of this transcription factor. C/EBPβ is critical for emergency granulopoiesis, and therefore we investigated whether the absence of C/EBPγ would affect this process. Deletion of C/EBPγ did not compromise the ability of the hematopoietic system to respond to G-CSF or LPS, since flow cytometric analysis revealed similar hematopoietic response in C/EBPγ ko mice in comparison to wt control animals. Interestingly, C/EBPγ ko mice showed reduced numbers of blood neutrophils during early phases of candidemia (wt 2.44x106/ml +/- 0.78, vs CEBPγ ko 1.55x106/ml +/- 0.59, p=0.031). In addition, the distribution of different developmental stages within the neutrophilic compartment in bone marrow was perturbed, leading to the accumulation of more immature granulocytic populations and reduced percentage of mature neutrophils. Altogether, these results indicate that C/EBPγ promotes accelarated neutrophilic production during early phases of emergency granulopoiesis upon Candida stimulation.
Conclusion
Taken together, our data unravel C/EBPγ as a player in the expansion of granulocytes during early phases of candidemia-induced emergency granulopoiesis. On the other hand, C/EBPγ appears to be dispensable for the regulation of steady-state hematopoiesis and bacteria-induced granulopoiesis.
Session topic: E-poster
Keyword(s): C/EBP, Granulopoiesis, Transcription factor
Type: Eposter Presentation
Background
CCAAT/enhancer binding protein γ (C/EBPγ) is a member of the C/EBP family of myeloid transcription factors, which are known as master regulators of hematopoiesis. Recently, it has been shown that increased C/EBPγ levels contribute to the block of neutrophilic differentiation in acute myeloid leukemias characterized by C/EBPα hypermethylation. Hovewer, the function of C/EBPγ in normal and stress-induced hematopoiesis remains largely unknown.
Aims
In this study we investigate the role of C/EBPγ in hematopoiesis both in steady-state and under stress conditions.
Methods
We generated a C/EBPγ conditional knockout murine model, which allows tissue and time specific excision of C/EBPγ. These mice were crossed to Vav-1Cre deleter strain to excise C/EBPγ specifically in the hematopoietic system from early embryonic stages. We employed C/EBPγ f/f Vav-1Cre- and C/EBPγ f/f Vav-1Cre+ mice, refered here as wt and C/EBPγ ko respectively. First, frequency of distinct hematopoietic lineages in bone marrow, spleen, and blood of C/EBPγ ko mice was determined by flow cytometry. Next, to elucidate whether C/EBPγ is necessary for stress induced granulopoiesis, in vivo administration of different stimuli, including lipopolysacharide (LPS), granulocyte colony-stimulating factor (G-CSF) and Candida albicans, was used to model bacteria- or candidemia-induced emergency granulopoiesis. Mice were sacrified and examined 24 hours after infection since we focused on early phases of granulopoiesis. Differential cell counting and flow cytometric analysis were performed to assess whether C/EBPγ is involved in demand-accelerated neutrophilic production.
Results
Mice lacking C/EBPγ within the hematopoietic system presented partially reduced levels of blood neutrophils (wt 1.438x106/ml -/+ 0.114 vs CEBPγ ko 0.988x106/ml -/+ 0.078, p=0.0021), although this reduction did not result in any signs of sickness. Analysis of other cell populations, including progenitors and hematopoietic stem cells, did not reveal further differences between wt and C/EBPγ ko mice. These data suggest that hematopoietic-specific genetic ablation of C/EBPγ is not critical for steady-state hematopoiesis. Since C/EBPγ forms heterodimers with another C/EBP member, C/EBPβ, we determined whether C/EBPγ can modulate the function of this transcription factor. C/EBPβ is critical for emergency granulopoiesis, and therefore we investigated whether the absence of C/EBPγ would affect this process. Deletion of C/EBPγ did not compromise the ability of the hematopoietic system to respond to G-CSF or LPS, since flow cytometric analysis revealed similar hematopoietic response in C/EBPγ ko mice in comparison to wt control animals. Interestingly, C/EBPγ ko mice showed reduced numbers of blood neutrophils during early phases of candidemia (wt 2.44x106/ml +/- 0.78, vs CEBPγ ko 1.55x106/ml +/- 0.59, p=0.031). In addition, the distribution of different developmental stages within the neutrophilic compartment in bone marrow was perturbed, leading to the accumulation of more immature granulocytic populations and reduced percentage of mature neutrophils. Altogether, these results indicate that C/EBPγ promotes accelarated neutrophilic production during early phases of emergency granulopoiesis upon Candida stimulation.
Conclusion
Taken together, our data unravel C/EBPγ as a player in the expansion of granulocytes during early phases of candidemia-induced emergency granulopoiesis. On the other hand, C/EBPγ appears to be dispensable for the regulation of steady-state hematopoiesis and bacteria-induced granulopoiesis.
Session topic: E-poster
Keyword(s): C/EBP, Granulopoiesis, Transcription factor
Abstract: E1126
Type: Eposter Presentation
Background
CCAAT/enhancer binding protein γ (C/EBPγ) is a member of the C/EBP family of myeloid transcription factors, which are known as master regulators of hematopoiesis. Recently, it has been shown that increased C/EBPγ levels contribute to the block of neutrophilic differentiation in acute myeloid leukemias characterized by C/EBPα hypermethylation. Hovewer, the function of C/EBPγ in normal and stress-induced hematopoiesis remains largely unknown.
Aims
In this study we investigate the role of C/EBPγ in hematopoiesis both in steady-state and under stress conditions.
Methods
We generated a C/EBPγ conditional knockout murine model, which allows tissue and time specific excision of C/EBPγ. These mice were crossed to Vav-1Cre deleter strain to excise C/EBPγ specifically in the hematopoietic system from early embryonic stages. We employed C/EBPγ f/f Vav-1Cre- and C/EBPγ f/f Vav-1Cre+ mice, refered here as wt and C/EBPγ ko respectively. First, frequency of distinct hematopoietic lineages in bone marrow, spleen, and blood of C/EBPγ ko mice was determined by flow cytometry. Next, to elucidate whether C/EBPγ is necessary for stress induced granulopoiesis, in vivo administration of different stimuli, including lipopolysacharide (LPS), granulocyte colony-stimulating factor (G-CSF) and Candida albicans, was used to model bacteria- or candidemia-induced emergency granulopoiesis. Mice were sacrified and examined 24 hours after infection since we focused on early phases of granulopoiesis. Differential cell counting and flow cytometric analysis were performed to assess whether C/EBPγ is involved in demand-accelerated neutrophilic production.
Results
Mice lacking C/EBPγ within the hematopoietic system presented partially reduced levels of blood neutrophils (wt 1.438x106/ml -/+ 0.114 vs CEBPγ ko 0.988x106/ml -/+ 0.078, p=0.0021), although this reduction did not result in any signs of sickness. Analysis of other cell populations, including progenitors and hematopoietic stem cells, did not reveal further differences between wt and C/EBPγ ko mice. These data suggest that hematopoietic-specific genetic ablation of C/EBPγ is not critical for steady-state hematopoiesis. Since C/EBPγ forms heterodimers with another C/EBP member, C/EBPβ, we determined whether C/EBPγ can modulate the function of this transcription factor. C/EBPβ is critical for emergency granulopoiesis, and therefore we investigated whether the absence of C/EBPγ would affect this process. Deletion of C/EBPγ did not compromise the ability of the hematopoietic system to respond to G-CSF or LPS, since flow cytometric analysis revealed similar hematopoietic response in C/EBPγ ko mice in comparison to wt control animals. Interestingly, C/EBPγ ko mice showed reduced numbers of blood neutrophils during early phases of candidemia (wt 2.44x106/ml +/- 0.78, vs CEBPγ ko 1.55x106/ml +/- 0.59, p=0.031). In addition, the distribution of different developmental stages within the neutrophilic compartment in bone marrow was perturbed, leading to the accumulation of more immature granulocytic populations and reduced percentage of mature neutrophils. Altogether, these results indicate that C/EBPγ promotes accelarated neutrophilic production during early phases of emergency granulopoiesis upon Candida stimulation.
Conclusion
Taken together, our data unravel C/EBPγ as a player in the expansion of granulocytes during early phases of candidemia-induced emergency granulopoiesis. On the other hand, C/EBPγ appears to be dispensable for the regulation of steady-state hematopoiesis and bacteria-induced granulopoiesis.
Session topic: E-poster
Keyword(s): C/EBP, Granulopoiesis, Transcription factor
Type: Eposter Presentation
Background
CCAAT/enhancer binding protein γ (C/EBPγ) is a member of the C/EBP family of myeloid transcription factors, which are known as master regulators of hematopoiesis. Recently, it has been shown that increased C/EBPγ levels contribute to the block of neutrophilic differentiation in acute myeloid leukemias characterized by C/EBPα hypermethylation. Hovewer, the function of C/EBPγ in normal and stress-induced hematopoiesis remains largely unknown.
Aims
In this study we investigate the role of C/EBPγ in hematopoiesis both in steady-state and under stress conditions.
Methods
We generated a C/EBPγ conditional knockout murine model, which allows tissue and time specific excision of C/EBPγ. These mice were crossed to Vav-1Cre deleter strain to excise C/EBPγ specifically in the hematopoietic system from early embryonic stages. We employed C/EBPγ f/f Vav-1Cre- and C/EBPγ f/f Vav-1Cre+ mice, refered here as wt and C/EBPγ ko respectively. First, frequency of distinct hematopoietic lineages in bone marrow, spleen, and blood of C/EBPγ ko mice was determined by flow cytometry. Next, to elucidate whether C/EBPγ is necessary for stress induced granulopoiesis, in vivo administration of different stimuli, including lipopolysacharide (LPS), granulocyte colony-stimulating factor (G-CSF) and Candida albicans, was used to model bacteria- or candidemia-induced emergency granulopoiesis. Mice were sacrified and examined 24 hours after infection since we focused on early phases of granulopoiesis. Differential cell counting and flow cytometric analysis were performed to assess whether C/EBPγ is involved in demand-accelerated neutrophilic production.
Results
Mice lacking C/EBPγ within the hematopoietic system presented partially reduced levels of blood neutrophils (wt 1.438x106/ml -/+ 0.114 vs CEBPγ ko 0.988x106/ml -/+ 0.078, p=0.0021), although this reduction did not result in any signs of sickness. Analysis of other cell populations, including progenitors and hematopoietic stem cells, did not reveal further differences between wt and C/EBPγ ko mice. These data suggest that hematopoietic-specific genetic ablation of C/EBPγ is not critical for steady-state hematopoiesis. Since C/EBPγ forms heterodimers with another C/EBP member, C/EBPβ, we determined whether C/EBPγ can modulate the function of this transcription factor. C/EBPβ is critical for emergency granulopoiesis, and therefore we investigated whether the absence of C/EBPγ would affect this process. Deletion of C/EBPγ did not compromise the ability of the hematopoietic system to respond to G-CSF or LPS, since flow cytometric analysis revealed similar hematopoietic response in C/EBPγ ko mice in comparison to wt control animals. Interestingly, C/EBPγ ko mice showed reduced numbers of blood neutrophils during early phases of candidemia (wt 2.44x106/ml +/- 0.78, vs CEBPγ ko 1.55x106/ml +/- 0.59, p=0.031). In addition, the distribution of different developmental stages within the neutrophilic compartment in bone marrow was perturbed, leading to the accumulation of more immature granulocytic populations and reduced percentage of mature neutrophils. Altogether, these results indicate that C/EBPγ promotes accelarated neutrophilic production during early phases of emergency granulopoiesis upon Candida stimulation.
Conclusion
Taken together, our data unravel C/EBPγ as a player in the expansion of granulocytes during early phases of candidemia-induced emergency granulopoiesis. On the other hand, C/EBPγ appears to be dispensable for the regulation of steady-state hematopoiesis and bacteria-induced granulopoiesis.
Session topic: E-poster
Keyword(s): C/EBP, Granulopoiesis, Transcription factor
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