Project description:Upon systemic bacterial infection, hematopoietic stem and progenitor cells (HSPCs) migrate to the periphery in order to supply a sufficient number of immune cells. Although pathogen-associated molecular patterns (PAMPs) reportedly mediate HSPC activation, how HSPCs detect pathogen invasion in vivo remains elusive. Bacteria use the second messenger bis-(3’-5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) for a variety of activities. Here we report that c-di-GMP comprehensively regulates both HSPCs and their niche cells through an innate immune sensor, STING, thereby inducing entry into the cell cycle and mobilization of HSPCs, while decreasing the number and repopulation capacity of long-term hematopoietic stem cells (LT-HSCs). Furthermore, we show that type I IFN acts as a downstream target of c-di-GMP to inhibit HSPC expansion in the spleen, while TGF-β1 is required for c-di-GMP-dependent splenic HSPC expansion. Our results define novel machinery underlying dynamic regulation of HSPCs and their niches during bacterial infection through c-di-GMP/STING signaling. Ten-week-old mice were intraperitoneally administered PBS or 200 nmol c-di-GMP, and CD150+ CD41- CD48- CD34- Flt3- LSK cells of pooled bone marrow from 10 mice per group were sorted 3 days later. mRNA was then extracted using RNeasy micro (Qiagen). Likewise, CD45- Ter-119- CD31- CD140a+ CD51+ MSCs and CD45- Ter119- CD31+ endothelial cells from c-di-GMP-treated or untreated mice were sorted and mRNA was extracted. cDNA was synthesized from mRNA and hybridized to gene chip Mouse60k (Agilent Technologies) and expression levels analyzed.
Project description:Upon systemic bacterial infection, hematopoietic stem and progenitor cells (HSPCs) migrate to the periphery in order to supply a sufficient number of immune cells. Although pathogen-associated molecular patterns (PAMPs) reportedly mediate HSPC activation, how HSPCs detect pathogen invasion in vivo remains elusive. Bacteria use the second messenger bis-(3’-5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) for a variety of activities. Here we report that c-di-GMP comprehensively regulates both HSPCs and their niche cells through an innate immune sensor, STING, thereby inducing entry into the cell cycle and mobilization of HSPCs, while decreasing the number and repopulation capacity of long-term hematopoietic stem cells (LT-HSCs). Furthermore, we show that type I IFN acts as a downstream target of c-di-GMP to inhibit HSPC expansion in the spleen, while TGF-β1 is required for c-di-GMP-dependent splenic HSPC expansion. Our results define novel machinery underlying dynamic regulation of HSPCs and their niches during bacterial infection through c-di-GMP/STING signaling.
Project description:From mice, strand-specific RNA-Seq of granulocyte-myeloid progenitors (GMP) and hematopoietic stem cells (HSC). Cancer stem cells (CSC) were created with MLL-ENL transfections using puromycin for both GMP and HSCs. Further knock-outs were created of -catenin (Ctnnb1) and Hoxa9.
Project description:C-di-GMP signaling can directly influence bacterial behavior by affecting the functionality of c-di-GMP-binding proteins. In addition, c-di-GMP can exert an indirect and more global effect on gene transcription or translation, e.g. via riboswitches or by binding to transcription factors. In this study, we investigated the effects of changes in intracellular c-di-GMP levels on gene expression and protein production in the opportunistic pathogen Pseudomonas aeruginosa. We induced c-di-GMP production via an ectopically introduced diguanylate cyclase and recorded the transcriptional, translational as well as proteomic profile of the cells. We demonstrate that rising levels of c-di-GMP in P. aeruginosa under growth conditions otherwise characterized by low c-di-GMP levels immediately cause a switch to a non-motile, auto-aggregative phenotype. This switch became apparent before any c-di-GMP-dependent role on transcription, translation, or protein abundance could be observed. Our results indicate that sudden rises in global c-di-GMP pools affect the P. aeruginosa phenotype via an alteration of protein functionality, rather than an impact on global gene transcription or translation.
Project description:Shewanella spp. possess a broad respiratory versatility, which contributes to the occupation of hypoxic/anoxic environmental or host-associated niches. Here we observed a strain-specific induction of biofilm formation in response to supplementation with the anaerobic electron acceptors dimethyl sulfoxide (DMSO) and nitrate in a panel of Shewanella algae isolates. The respiration-driven biofilm response is not observed in DMSO and nitrate reductase deletion mutants of the type strain S. algae CECT 5071, and can be restored upon complementation with the corresponding reductase operon(s) but not by an operon containing a catalytically inactive nitrate reductase. The distinct transcriptional changes, proportional to the effect of these compounds on biofilm formation, include cyclic di-GMP (c-di-GMP) turnover genes. In support, ectopic expression of the c-di-GMP phosphodiesterase YhjH of Salmonella Typhimurium but not its catalytically inactive variant decreased biofilm formation. The respiration-dependent biofilm response of S. algae may permit differential colonization of environmental or host niches.
Project description:Leukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible. Experiment Overall Design: A normal HSC enriched population, common myeloid progenitors, granulocyte macrophage progenitors, megakaryocyte progenitors, and leukemia stem cells (leukemic-GMP) were isolated and labeled RNA was hybridzed to Affymetrix microarrays
Project description:Although the ubiquitous bacterial secondary messenger cyclic diguanylate (c-di-GMP) plays important roles in various cellular functions including the formation of biofilm in a wide range of bacteria, its function in model plant pathogen Pseudomonas syringae is largely elusive. In order to test this in P. syringae, we overexpressed a diguanylate cyclase (YedQ) and a phosphodiesterase (YhjH) that are originally from Escherichia coli, resulting in high and low c-di-GMP levels in P. syringae, respectively. Through performing genome-wide RNA sequencing of these two strains, we found that c-di-GMP regulates (i) fliN, fliE and flhA genes, which are associated with flagellar assembly, (ii) alg8 and alg44, which are related to exopolysaccaride biosynthesis pathway, (iii) pvdE, pvdP and pvsA genes, related to siderophore biosynthesis pathway, and (iv) sodA, which is a superoxide dismutase. In particular, we identified five genes sensitive to elevated c-di-GMP level and constructed five luciferase-based reporters that effectively respond to intracellular level of c-di-GMP in P. syringae, which can be used to measure c-di-GMP levels in vivo in the future. Based on the RNA-seq results, phenotypic assays confirmed that c-di-GMP regulated many important biological pathways in P. syringae, such as negative regulation of type III secretion system (T3SS) and motility as well as positive regulation of EPS production, siderophore production and oxidative stress resistance. Taken together, the present study demonstrated that c-di-GMP is closely related to virulence and stress response in P. syringae, suggesting that tuning its level can be a new strategy to protect plants from the attack of this pathogen in the future.
Project description:Transcriptional profiling of gene expression between parental strain B31 and rrp1 mutant. Cyclic-di-GMP is a bacterial second messenger that modulates many biological processes. Although its role in bacterial pathogenesis during mammalian infection has been widely recognized, the role of c-di-GMP in pathogen's life cycle in vector hosts is less understood. The enzootic cycle of the Lyme disease pathogen Borrelia burgdorferi involves both a mammalian host and an Ixodes tick vector. The B. burgdorferi genome encodes a single copy of the diguanylate cyclase gene (rrp1), which is responsible for the production of c-di-GMP. To determine the role of c-di-GMP in the life cycle of B. burgdorferi, an Rrp1-deficient B. burgdorferi strain was generated. The rrp1 mutant remains infectious in the mammalian host, but could not survive in the tick vector. To identify the mechanisms of Rrp1 contributing to B. burgdorferi pathogenesis and gene regulation, microarray was employed to compare gene expression profiles between the parental strain B31 and the rrp1 mutant. Two-condition experiment, B31 vs. rrp1 mutant. Biological replicates: 3 B31, 3 rrp1 mutant, independently grown and harvested. One replicate (dye-swap) per array.
Project description:Leukemias and other cancers possess a rare population of cells capable of self-renewal, and eradication of these cancer stem cells is likely necessary for long-term cancer-free survival. Given that both normal and cancer stem cells are capable of self-renewal the extent to which cancer stem cells resemble normal tissue stem cells is a critical issue if targeted therapies are to be developed. We introduced the MLL-AF9 fusion protein encoded by the t(9;11)(p22;q23) found in human acute myelogenous leukemia (AML) into murine committed granulocyte-macrophage progenitors (GMP). The resultant leukemias contained cells with an immunophenotype similar to normal GMP that were highly enriched for leukemia stem cells (LSC). Detailed gene expression comparisons between normal hematopoietic stem cells (HSC), committed progenitors, and the LSC population demonstrated the LSC were globally more similar to the normal GMP than any other population. However, a subset of genes highly expressed in normal stem cells was re-activated in the LSC. These data demonstrate LSC can be generated from committed progenitors without widespread reprogramming of gene expression, and a leukemia self-renewal associated signature is activated in the process. Our findings define progression from normal hematopoietic progenitor to leukemia stem cell, and suggest that targeting a self-renewal program expressed in an abnormal context may be possible. Experiment Overall Design: RNA from normal GMP, GMP-like cells isolated from leukemic bone marrow (LGMP) and cells derived from the in vitro propagation of LGMP were hybridized to affymetrix microarrays.
Project description:The innate immune system responds to unique molecular signatures that are widely conserved among microbes but that are not normally present in host cells. Compounds that stimulate innate immune pathways may be valuable in the design of novel adjuvants, vaccines, and other immunotherapeutics.The cyclic dinucleotide cyclic-di-guanosine monophosphate (c-di-GMP) is a recently appreciated second messenger that plays critical regulatory roles in many species of bacteria but is not produced by eukaryotic cells. In vivo and in vitro studies have previously suggested that c-di-GMP is a potent immunostimulatory compound recognized by mouse and human cells. Here we provide evidence that c-di-GMP is sensed in the cytosol of mammalian cells via a novel immunosurveillance pathway. The potency of cytosolic signaling induced by cyclic-di- GMP is comparable to that induced by cytosolic delivery of DNA, and both nucleic acids induce a similar transcriptional profile, including triggering of type I interferons and coregulated genes via induction of TBK1, IRF3, NF-!B and MAP kinases. However, the cytosolic pathway that senses c-di-GMP appears to be distinct from all known nucleic acid-sensing pathways.Our results suggest a novel mechanism by which host cells can induce an inflammatory response to a widely produced bacterial ligand. Three-condition experiment: macrophages transfected with mono-GMP (negative control), double-stranded DNA (positive control), or cyclic-di-GMP (experimental condition). Biological replicates: two, independently treated, harvested, and hybridized to arrays. One replicate per array, except two technical replicates were performed for one of the positive control samples.