Project description:We performed RNAseq to identify miRNAs that were specifically down regulated in neutrophils, and RNAseq for identification of mRNA targets of miRNA-199 in neutrophils
Project description:Tumor-associated neutrophils are found in many types of cancer and are often reported to contribute to negative outcomes. Several studies have shown that the presence of TGF-β in the tumor microenvironment contributes to the skewing of neutrophils to have a more pro-tumor phenotype. However, the direct effects of TGF-β on neutrophil signaling and migration are unclear. We sought to characterize TGF-β signaling in both primary human neutrophils and the neutrophil-like cell line HL-60 and determine whether TGF-β directly induces neutrophil migration. We found that TGF-β1 does not induce neutrophil migration in either a transwell or an underagarose migration assay. However, TGF-β1 does activate signals canonically through SMAD3 and noncanonically through ERK1/2 in neutrophils in a time and dose-dependent manner. Additionally, TGF-β1 present in the tumor-conditioned media (TCM) is responsible for SMAD3 activation. Moreover, we discovered that TCM from aggressive breast cancer cells induces neutrophils to secrete leukotriene B4 (LTB4), which is a lipid mediator important for amplifying neutrophil recruitment. However, we found that TGF-β1 alone does not induce secretion of LTB4. We next performed RNA-sequencing to evaluate the effects of TGF-β1 and TCM on the neutrophil transcriptome. We found that TGF-β1 and TCM result in changes in gene transcription in HL-60 cells, specifically of two pro-tumor genes OSM and VEGFA. Together, our findings characterize the effects of TGF-β1 on neutrophil signaling, migration, and gene expression that can be applied to understanding the changes in neutrophils that occur in the tumor microenvironment.
Project description:Background. Mammalian cells are flexible and can rapidly change shape when they contract, adhere, or migrate. Their nucleus must be stiff enough to withstand cytoskeletal forces, but flexible enough to remodel as the cell changes shape. This is particularly important for cells migrating through constricted space, where the nuclear shape must change in order to fit through. This happens many times in the life cycle of a neutrophil, which must protect its chromatin from damage and disruption associated with migration. Results. Total RNA-sequencing identified that neutrophil migration through 5 or 14 µm pores was associated with changes in the transcript levels of inflammation and chemotaxis-related genes, when compared to unmigrated cells. Differentially expressed transcripts specific to migration with constriction were enriched for groups of genes associated with cytoskeleton remodelling. Hi-C was used to capture the genome organisation in control and migrated cells. Chromatin did not switch between the active (A) and inactive (B) compartments after migration. However, global depletion of mid- to long-range contacts was observed following active migration through the 5 µm pores. Chromatin contacts that decreased in frequency were enriched in inactive chromatin. Conclusion. Mid- to long-range contacts are preferentially lost within inactive chromatin, thus protecting transcriptionally active contacts from the disruptive effects of migration with constriction. This is consistent with current hypotheses implicating heterochromatin as the mechanoresponsive form of chromatin. Further investigation concerning the contribution of heterochromatin to stiffness, flexibility, and protection of nuclear function will be important for understanding cell migration in human health and disease.
Project description:Background. Mammalian cells are flexible and can rapidly change shape when they contract, adhere, or migrate. Their nucleus must be stiff enough to withstand cytoskeletal forces, but flexible enough to remodel as the cell changes shape. This is particularly important for cells migrating through constricted space, where the nuclear shape must change in order to fit through. This happens many times in the life cycle of a neutrophil, which must protect its chromatin from damage and disruption associated with migration. Results. Total RNA-sequencing identified that neutrophil migration through 5 or 14 µm pores was associated with changes in the transcript levels of inflammation and chemotaxis-related genes, when compared to unmigrated cells. Differentially expressed transcripts specific to migration with constriction were enriched for groups of genes associated with cytoskeleton remodelling. Hi-C was used to capture the genome organisation in control and migrated cells. Chromatin did not switch between the active (A) and inactive (B) compartments after migration. However, global depletion of mid- to long-range contacts was observed following active migration through the 5 µm pores. Chromatin contacts that decreased in frequency were enriched in inactive chromatin. Conclusion. Mid- to long-range contacts are preferentially lost within inactive chromatin, thus protecting transcriptionally active contacts from the disruptive effects of migration with constriction. This is consistent with current hypotheses implicating heterochromatin as the mechanoresponsive form of chromatin. Further investigation concerning the contribution of heterochromatin to stiffness, flexibility, and protection of nuclear function will be important for understanding cell migration in human health and disease.
Project description:Expression of the activating transcription factor 3 (ATF3) gene is induced by Toll-like receptor (TLR) signaling. In turn, ATF3 protein inhibits the expression of various TLR-driven pro-inflammatory genes. Given its counter-regulatory role in diverse innate immune responses, we defined the effects of ATF3 on neutrophilic airway inflammation in mice. ATF3 deletion was associated with increased lipopolysaccharide (LPS)-driven airway epithelia production of CXCL1, but not CXCL2, findings concordant with a consensus ATF3-binding site identified solely in the Cxcl1 promoter. Unexpectedly, ATF3-deficient mice did not exhibit increased airway neutrophilia after LPS challenge. Bone marrow chimeras revealed a specific reduction in ATF3-/- neutrophil recruitment to wild type lungs. In vitro, ATF3-/- neutrophils exhibited a profound chemotaxis defect. Global gene expression analysis identified ablated Tiam2 expression in ATF3-/- neutrophils. TIAM2 regulates cellular motility by activating Rac1-mediated focal adhesion disassembly. Notably, ATF3-/- and ATF3-sufficient TIAM2 knockdown neutrophils, both lacking TIAM2, exhibited increased focal complex area, along with excessive CD11b-mediated F-actin polymerization. Together, our data describe a dichotomous role for ATF3-mediated regulation of neutrophilic responses: inhibition of neutrophil chemokine production, but promotion of neutrophil chemotaxis. Ly6G+ neutrophils were purified by magnetic beads from WT or ATF3 KO bone marrow and RNA was immediately isolated for global gene expression using microarrays.