Project description:Lipocalin 24p3 (24p3) is a neutrophil secondary granule protein. 24p3 is also a siderocalin, which binds several bacterial siderophores. It was therefore proposed that synthesis and secretion of 24p3 by stimulated macrophages or release of 24p3 upon neutrophil degranulation sequesters iron-laden siderophores to attenuate bacterial growth. Accordingly, 24p3-deficient mice are susceptible to bacterial pathogens whose siderophores would normally be chelated by 24p3. Specific granule deficiency (SGD) is a rare congenital disorder characterized by complete absence of proteins in secondary granules. Neutrophils from SGD patients, who are prone to bacterial infections, lack normal functions but the potential role of 24p3 in neutrophil dysfunction in SGD is not known. Here we show that neutrophils from 24p3-deficient mice are defective in many neutrophil functions. Specifically, neutrophils in 24p3-deficient mice do not extravasate to sites of infection and are defective for chemotaxis. A transcriptome analysis revealed that genes that control cytoskeletal reorganization are selectively suppressed in 24p3-deficient neutrophils. Additionally, small regulatory RNAs (miRNAs) that control upstream regulators of cytoskeletal proteins are also increased in 24p3-deficient neutrophils. Further, 24p3-deficient neutrophils failed to phagocytose bacteria, which may account for the enhanced sensitivity of 24p3-deficient mice to both intracellular (Listeria monocytogenes) and extracellular (Candida albicans, Staphylococcus aureus) pathogens. Interestingly, Listeria does not secrete siderophores and additionally, the siderophore secreted by Candida is not sequestered by 24p3. Therefore, the heightened sensitivity of 24p3-deficient mice to these pathogens is not due to sequestration of siderophores limiting iron availability, but is a consequence of impaired neutrophil function. Key words: Lipocalin, 24p3, neutrophils, cell motility, chemotaxis, MIRNA-362-3p To address the role of lipocalin 2 in unstimulated and fMLP-stimulated neutrophils derived from mouse bone marrow, we performed micorarray analysis of gene expression in unstimulated wild type (N=3), unstimulated lcn2 knockout (N=3), fMLP-stimulated wild type (N=2) and fMLP-stimulated lcn2 knockout (N=2) neutrophils. Upon stimulation, neutrophils were treated by fMLP at 10 micromolar for 20 minutes at 37 centigrade.
Project description:Lipocalin 24p3 (24p3) is a neutrophil secondary granule protein. 24p3 is also a siderocalin, which binds several bacterial siderophores. It was therefore proposed that synthesis and secretion of 24p3 by stimulated macrophages or release of 24p3 upon neutrophil degranulation sequesters iron-laden siderophores to attenuate bacterial growth. Accordingly, 24p3-deficient mice are susceptible to bacterial pathogens whose siderophores would normally be chelated by 24p3. Specific granule deficiency (SGD) is a rare congenital disorder characterized by complete absence of proteins in secondary granules. Neutrophils from SGD patients, who are prone to bacterial infections, lack normal functions but the potential role of 24p3 in neutrophil dysfunction in SGD is not known. Here we show that neutrophils from 24p3-deficient mice are defective in many neutrophil functions. Specifically, neutrophils in 24p3-deficient mice do not extravasate to sites of infection and are defective for chemotaxis. A transcriptome analysis revealed that genes that control cytoskeletal reorganization are selectively suppressed in 24p3-deficient neutrophils. Additionally, small regulatory RNAs (miRNAs) that control upstream regulators of cytoskeletal proteins are also increased in 24p3-deficient neutrophils. Further, 24p3-deficient neutrophils failed to phagocytose bacteria, which may account for the enhanced sensitivity of 24p3-deficient mice to both intracellular (Listeria monocytogenes) and extracellular (Candida albicans, Staphylococcus aureus) pathogens. Interestingly, Listeria does not secrete siderophores and additionally, the siderophore secreted by Candida is not sequestered by 24p3. Therefore, the heightened sensitivity of 24p3-deficient mice to these pathogens is not due to sequestration of siderophores limiting iron availability, but is a consequence of impaired neutrophil function. Key words: Lipocalin, 24p3, neutrophils, cell motility, chemotaxis, MIRNA-362-3p To address the role of lipocalin 2 in regulating miRNA expression profiling in neutrophils derived from mouse bone marrow, we performed microarray analysis of miRNAs in wild type (N=2) and lcn2 knockout (N=2) neutrophils.
Project description:By performing RNA-seq analysis on bone marrow neutrophils from the Alkbh5-deficient mice and Wild-type littermates undergoing CLP-induced sepsis, we want to investigate the effect of ALKBH5 on transcriptional landscape of mouse bone marrow neutrophils during bacterial infection. Then, we performed gene expression profiling and Gene Ontology enrichment analysis of the significantly differentially expressed genes using data obtained from RNA-seq.
Project description:RNA expression in Srf wildtype and knockout primary bone marrow derived mature neutrophils was determined via RNA sequencing Mature Gr1 high, 7/4 high, SSC high neutrophils were sorted from Srf WT and KO mouse bone marrow and submitted for RNA sequencing
Project description:Neutrophil homeostasis is maintained, in part, by the regulated release of neutrophils from the bone marrow. Constitutive expression of the chemokine CXCL12 by bone marrow stromal cells provides a key retention signal for neutrophils in the bone marrow through activation of its receptor CXCR4. Herein, we show that the ELR chemokines CXCL1 and CXCL2 are constitutively expressed by bone marrow endothelial cells and osteoblasts, and CXCL2 expression is induced in endothelial cells during granulocyte colony-stimulating factor (G-CSF)-induced neutrophil mobilization. Neutrophils lacking CXCR2, the receptor for CXCL1 and CXCL2, are preferentially retained in the bone marrow, reproducing a myelokathexis phenotype. Transient disruption of CXCR4 failed to mobilize CXCR2 neutrophils. However, doubly deficient neutrophils (CXCR2-/- CXCR4-/-) displayed constitutive mobilization, showing that CXCR4 plays a dominant role. Collectively, these data suggest that CXCR2 signaling is a second chemokine axis that interacts antagonistically with CXCR4 to regulate neutrophil release from the bone marrow. We used gene expression microarrays to determine the changes in osteoblasts and bone marrow endothelial cells after G-CSF treatment. 3 untreated and G-CSF-treated osteoblast samples and 4 untreated and G-CSF-treated endothelial samples.
Project description:The CCAAT/enhancer-binding proteins (CEBPs) are transcription factors involved in hematopoietic cell development and induction of several inflammatory mediators. Here, we generated CEBP-beta (CEBPB) and CEBP-epsilon (CEBPE) double-knockout (bbee) mice and compared their phenotypes to those of single-deficient (bbEE and BBee) and wild-type (BBEE) mice. The bbee mice were highly susceptible to fatal infections and died within 2-3 months. Morphologically, their neutrophils were blocked at the myelocytes/metamyelocytes stage, and clonogenic assays of bone marrow cells indicated a significant decrease in the number of myeloid colonies of the bbee mice. In addition, the proportion of hematopoietic progenitor cells [Lin(-)Sca1(+)c-Kit(+)] in the bone marrow of the bbee mice was significantly increased, reflecting the defective differentiation of the myeloid compartment. Furthermore, microarray expression analysis of lipopolysaccharide (LPS)- and interferon-gamma (IFN-gamma)-activated bone marrow-derived macrophages from bbee compared to single knockout mice revealed decreased expression of essential immune response-related genes and networks, including some direct CEBP targets such as Marco and Clec4e. Overall, the phenotype of the bbee mice is distinct from either the bbEE or BBee mice, demonstrating that both transcription factors are crucial for the maturation of neutrophils and macrophages, as well as the innate immune system, and can at least in part compensate for each other in the single knockout mice. To rule out the regulatory influence of both CEBPB and CEBPE on macrophage-related genes, expression analysis of bone marrow-derived macrophages was performed. Macrophages were derived from murine bone marrow with the use of murine M-CSF. The macrophages were stimulated with both LPS (100 ng) and IFN-gamma (100 ng) for 24h, and RNA was extracted for array analysis. Overall, RNA was extracted from stimulated macrophages of one WT mouse, one CEBPB-KO mouse, one CEBPE-KO mouse and one double-KO mouse.
Project description:To analyse the Irf4-dependent transcriptional changes of mouse bone marrow-derived macrophages (BMM) in response to IL-4, we have employed whole genome microarray expression profiling. For this purpose, bone marrow cells were isolated from 8 to 12 weeks old Irf4-deficient or heterozygous mice and cultured in the presence of the macrophage colony-stimulating factor (M-CSF) . After seven days of culture, IL-4 was added for 4 and 18 hours. Keywords: Mouse strain comparision; Gene expression profiling IL-4 induced gene expression was investigated in mouse bone marrow-derived macrophages (BMM) of Irf4-deficient or heterozygous mice. BMM were incubated with mouse recombinant IL-4 for 4 or 18 hours or without for 18 hours. Three independent experiments were performed at each time point (mock, 4 and 18 hours) using littermates for each experiment.
Project description:Maturation, age, tissue localization and functional capacity all drive neutrophil heterogeneity. In mouse models of cancer, we found that Ly6GInt neutrophils were abundant, and their frequency correlated with metastatic potential. Only Ly6G surface expression was found to accurately identify neutrophil maturity by flow cytometry across models, with other markers being model specific. Using several stimuli, we found that Ly6GInt neutrophils are bone fide ‘immature neutrophils’ with reduced immune regulatory and adhesion capacity. The spleen is a site of neutrophil production in homeostasis and cancer. Strikingly, we found that neutrophils mature and undergo post-mitotic transit faster in the spleen than in the bone marrow with unique transcriptional profiles for splenic Ly6GInt and Ly6GHi neutrophils. We propose that developmental origin is critical in neutrophil identity and postulate that neutrophils that develop in the spleen supplement the bone marrow by providing an intermediate more mature reserve before emergency haematopoiesis.