Project description:Mast cells and basophils are developmentally related cells whose activation is a hallmark of allergy. Functionally, mast cells and basophils overlap in their ability to produce several mediators, including histamine and granule proteases, but studies have increasingly demonstrated non-redundant roles. To characterize the transcriptional heterogeneity of mast cells and basophils upon their activation, we performed large-scale comparative microarrays of murine bone marrow–derived mast cells (BMMCs) and basophils (BMBs) at rest, upon an adaptive-type activation (IgE crosslinking), or upon an innate-type activation (IL-33 stimulation). Hierarchical clustering demonstrated that BMMCs and BMBs shared specific activation-associated transcriptional signatures but differed in others, both between cell type and between activation mode. In BMMCs, IgE crosslinking upregulated 785 genes including Egr2, Ccl1, and Fxyd6, while IL-33 stimulation induced 823 genes including Ccl1, Egr2, and Il1b. Focused bioinformatics pathway analysis demonstrated that IgE activation aligned with processes such as oxidative phosphorylation, angiogenesis, and the p53 pathway. The IL-33–activated transcriptome was enriched in genes commonly altered by NF-B in response to TNF, by IL-6 via STAT3, and in response to IFN. Furthermore, BMBs activated via IgE crosslinking selectively induced immune response genes Ccl1, Il3, and Il2 compared to IL-33–stimulated BMBs. Principal-component analysis revealed key cell- and activation-specific clustering. Overall, our data demonstrate that mast cells and basophils have cell- and activation-specific transcriptional responses and suggest that context-specific gene networks and pathways may shape how the immune system responds to allergens and innate cytokines.
Project description:We performed large-scale comparative microarrays of bone marrow -derived mast cells and basophils at rest, upon an adaptive-type action (IgE-crosslinking) or upon innate-type activation (IL-33-activation).
Project description:We performed large-scale comparative microarrays of bone marrow -derived mast cells and basophils at rest, upon an adaptive-type action (IgE-crosslinking) or upon innate-type activation (IL-33-activation).
Project description:To investigate the mechanisms by which C/EBPa drives basophil differentiation and maintains basophil identity, we examined whether or not C/EBPa promotes basophil molecular programming and simultaneously represses mast cell molecular programming. We performed genome-wide gene expression profiling on basophils and mast cells and found that 6798 genes were shared by mast cells and basophils; 2033 genes were expressed 2-10 (log2 1-3.3)-fold higher in basophils (differentially expressed in basophils); and 413 genes were expressed greater than 10 (log2 3.3)-fold in basophils (highly expressed in basophils). On the other hand, we found 569 genes were expressed 2-10 (log2 -1 to -3.3) fold higher in mast cells and 171 genes were highly expressed in mast cells [greater than 10 fold (log2 -3.3)]. We treated purified basophils prepared from Cebpaf/f RosaYFP/creER mice and Cebpa+/+ RosaYFP/creER control mice with or without 4HT treatment for five days. Gene expression in the treated basophils was analyzed using microarray analysis. Overall, deletion of C/EBPa in basophils resulted in a reduction of mRNA expression for 248 genes and led to an increase in mRNA expression for 255 genes. The majority of the C/EBPa-regulated genes were either differentially or highly expressed in basophils or mast cells. In this study, we compared gene expression in basophils and mast cell and identified genes which specifically expressed in basophils and mast cells. By using Cebpa conditional knock out mice, we identified Cebpa regulated genes in basophils.
Project description:The high-affinity Fc receptor for IgE, mainly present on mast cells and basophils, plays a crucial role in the development of allergic diseases. Monomeric IgE binding to receptor regulates mast cell survival, differentiation, and maturation. However, the underlying molecular mechanism remains unclear. Here we demonstrate that, prior to IgE binding, IgE receptor mostly exists as a homo-dimer on human mast cell membrane. The structure of human IgE receptor confirms the dimeric organization. Cholesterol-like molecules embedded within the transmembrane domain may stabilize the dimeric assembly. Upon IgE binding, the dimeric IgE receptor dissociates into two protomers, each binding to an IgE molecule. Importantly, this process elicits transcriptional activation of Egr1/3 and Ccl2 in rat basophils, which can be attenuated by inhibiting the IgE receptor dimer-to-monomer transition. Collectively, our study unveils the mechanism of antigen-independent, IgE-mediated receptor activation.
Project description:To investigate the mechanisms by which C/EBPa drives basophil differentiation and maintains basophil identity, we examined whether or not C/EBPa promotes basophil molecular programming and simultaneously represses mast cell molecular programming. We performed genome-wide gene expression profiling on basophils and mast cells and found that 6798 genes were shared by mast cells and basophils; 2033 genes were expressed 2-10 (log2 1-3.3)-fold higher in basophils (differentially expressed in basophils); and 413 genes were expressed greater than 10 (log2 3.3)-fold in basophils (highly expressed in basophils). On the other hand, we found 569 genes were expressed 2-10 (log2 -1 to -3.3) fold higher in mast cells and 171 genes were highly expressed in mast cells [greater than 10 fold (log2 -3.3)]. We treated purified basophils prepared from Cebpaf/f RosaYFP/creER mice and Cebpa+/+ RosaYFP/creER control mice with or without 4HT treatment for five days. Gene expression in the treated basophils was analyzed using microarray analysis. Overall, deletion of C/EBPa in basophils resulted in a reduction of mRNA expression for 248 genes and led to an increase in mRNA expression for 255 genes. The majority of the C/EBPa-regulated genes were either differentially or highly expressed in basophils or mast cells.
Project description:Immunoglobulin (Ig) E-mediated activation of mast cells and basophils underlies allergic diseases such as asthma. Histamine-releasing factor (HRF), also known as translationally controlled tumor protein (TCTP) and fortilin, is a highly conserved protein with both intracellular and extracellular functions. Secreted HRF can stimulate histamine release and IL-4 and IL-13 production from IgE-sensitized basophils and mast cells. HRF is found in nasal, skin blister and bronchoalveolar lavage (BAL) fluids during late-phase allergic reactions (LPRs), which implicates HRF in the LPR and chronic allergic inflammation. Here we identify a subset of IgE and IgG antibodies as HRF-interacting molecules. HRF can exist as a dimer and bind to immunoglobulins (Igs) via interactions of its N-terminal and internal regions with the Fab region of Igs. Therefore, HRF together with HRF-reactive IgE can activate mast cells in vitro. The Ig-interacting HRF peptides that block HRF-Ig interactions can inhibit IgE+HRF-induced mast cell activation and in vivo cutaneous anaphylaxis and airway inflammation. Intranasally administered HRF can recruit inflammatory immune cells to the lung in naïve mice in a mast cell- and Fc receptor-dependent manner. These results strongly suggest the proinflammatory role of HRF in asthma and skin immediate hypersensitivity. A total of 6 samples were analyzed; wild type C57BL/6, FcRg KO and FceRIa KO mice were challenged with PBS (control) or mouse histamien-releasing factor
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.