scholarly journals Bacterial Nucleoid-Associated Protein Uncouples Transcription Levels from Transcription Timing

mBio ◽  
2014 ◽  
Vol 5 (5) ◽  
Author(s):  
Igor Zwir ◽  
Won-Sik Yeo ◽  
Dongwoo Shin ◽  
Tammy Latifi ◽  
Henry Huang ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Target Genes ◽  
Transcriptional Regulator ◽  
Mrna Levels ◽  
Content Type ◽  
Expression Of Genes ◽  
Serovar Typhimurium ◽  
Expression Behavior

ABSTRACTThe histone-like nucleoid-structuring (H-NS) protein binds to horizontally acquired genes in the bacteriumSalmonella entericaserovar Typhimurium, silencing their expression. We now report that overcoming the silencing effects of H-NS imposes a delay in the expression of genes activated by the transcriptional regulator PhoP. We determine that PhoP-activated genes ancestral toSalmonellaare expressed before those acquired horizontally. This expression timing reflects thein vivooccupancy of the corresponding promoters by the PhoP protein. These results are surprising because some of these horizontally acquired genes reached higher mRNA levels than ancestral genes expressed earlier and were transcribed from promoters harboring PhoP-binding sites with higherin vitroaffinity for the PhoP protein. Our findings challenge the often-made assumption that for genes coregulated by a given transcription factor, early genes are transcribed to higher mRNA levels than those transcribed at later times. Moreover, they provide a singular example of how gene ancestry can impact expression timing.IMPORTANCEWe report that gene ancestry dictates the expression behavior of genes under the direct control of theSalmonellatranscriptional regulator PhoP. That is, ancestral genes are transcribed before horizontally acquired genes. This reflects both the need to overcome silencing by the H-NS protein of the latter genes and the architecture of the corresponding promoters. Unexpectedly, transcription levels do not reflect transcription timing. Our results illustrate how a bacterium can exhibit an elaborate temporal expression behavior among genes coregulated by a transcription factor even though the products encoded by the target genes do not participate in a morphological or developmental pathway.

scholarly journals Arsenic Directly Binds to and Activates the Yeast AP-1-Like Transcription Factor Yap8

2015 ◽  
Vol 36 (6) ◽  
pp. 913-922 ◽  
Author(s):  
Nallani Vijay Kumar ◽  
Jianbo Yang ◽  
Jitesh K. Pillai ◽  
Swati Rawat ◽  
Carlos Solano ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Transcriptional Activation ◽  
Transcriptional Response ◽  
Transcriptional Regulator ◽  
Yeast Protein ◽  
Content Type ◽  
Arsenic Tolerance ◽  
Arsenic Sensing

The AP-1-like transcription factor Yap8 is critical for arsenic tolerance in the yeastSaccharomyces cerevisiae. However, the mechanism by which Yap8 senses the presence of arsenic and activates transcription of detoxification genes is unknown. Here we demonstrate that Yap8 directly binds to trivalent arsenite [As(III)]in vitroandin vivoand that approximately one As(III) molecule is bound per molecule of Yap8. As(III) is coordinated by three sulfur atoms in purified Yap8, and our genetic and biochemical data identify the cysteine residues that form the binding site as Cys132, Cys137, and Cys274. As(III) binding by Yap8 does not require an additional yeast protein, and Yap8 is regulated neither at the level of localization nor at the level of DNA binding. Instead, our data are consistent with a model in which a DNA-bound form of Yap8 acts directly as an As(III) sensor. Binding of As(III) to Yap8 triggers a conformational change that in turn brings about a transcriptional response. Thus, As(III) binding to Yap8 acts as a molecular switch that converts inactive Yap8 into an active transcriptional regulator. This is the first report to demonstrate how a eukaryotic protein couples arsenic sensing to transcriptional activation.

scholarly journals Needle-Free Delivery of Acetalated Dextran-Encapsulated AR-12 Protects Mice from Francisella tularensis Lethal Challenge

2016 ◽  
Vol 60 (4) ◽  
pp. 2052-2062 ◽  
Author(s):  
Ky V. Hoang ◽  
Heather Curry ◽  
Michael A. Collier ◽  
Hassan Borteh ◽  
Eric M. Bachelder ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Lethal Challenge ◽  
Content Type ◽  
Human Macrophages ◽  
Gentamicin Treatment ◽  
Significant Toxicity ◽  
Serovar Typhimurium ◽  
Spectrum Activity

ABSTRACTFrancisella tularensiscauses tularemia and is a potential biothreat. Given the limited antibiotics for treating tularemia and the possible use of antibiotic-resistant strains as a biowarfare agent, new antibacterial agents are needed. AR-12 is an FDA-approved investigational new drug (IND) compound that induces autophagy and has shown host-directed, broad-spectrum activityin vitroagainstSalmonella entericaserovar Typhimurium andF. tularensis. We have shown that AR-12 encapsulated within acetalated dextran (Ace-DEX) microparticles (AR-12/MPs) significantly reduces host cell cytotoxicity compared to that with free AR-12, while retaining the ability to controlS.Typhimurium within infected human macrophages. In the present study, the toxicity and efficacy of AR-12/MPs in controlling virulent type AF. tularensisSchuS4 infection were examinedin vitroandin vivo. No significant toxicity of blank MPs or AR-12/MPs was observed in lung histology sections when the formulations were given intranasally to uninfected mice. In histology sections from the lungs of intranasally infected mice treated with the formulations, increased macrophage infiltration was observed for AR-12/MPs, with or without suboptimal gentamicin treatment, but not for blank MPs, soluble AR-12, or suboptimal gentamicin alone. AR-12/MPs dramatically reduced the burden ofF. tularensisin infected human macrophages, in a manner similar to that of free AR-12. However,in vivo, AR-12/MPs significantly enhanced the survival ofF. tularensisSchuS4-infected mice compared to that seen with free AR-12. In combination with suboptimal gentamicin treatment, AR-12/MPs further improved the survival ofF. tularensisSchuS4-infected mice. These studies provide support for Ace-DEX-encapsulated AR-12 as a promising new therapeutic agent for tularemia.

scholarly journals The Transcriptional Regulator CpsY Is Important for Innate Immune Evasion in Streptococcus pyogenes

2016 ◽  
Vol 85 (3) ◽  
Author(s):  
Luis A. Vega ◽  
Kayla M. Valdes ◽  
Ganesh S. Sundar ◽  
Ashton T. Belew ◽  
Emrul Islam ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Immune Evasion ◽  
Immune Cell ◽  
Group A Streptococcus ◽  
Transcriptional Regulator ◽  
Innate Immune ◽  
Content Type ◽  
Human Host

ABSTRACTAs an exclusively human pathogen,Streptococcus pyogenes(the group A streptococcus [GAS]) has specifically adapted to evade host innate immunity and survive in multiple tissue niches, including blood. GAS can overcome the metabolic constraints of the blood environment and expresses various immunomodulatory factors necessary for survival and immune cell resistance. Here we present our investigation of one such factor, the predicted LysR family transcriptional regulator CpsY. The encoding gene,cpsY, was initially identified as being required for GAS survival in a transposon-site hybridization (TraSH) screen in whole human blood. CpsY is homologous with transcriptional regulators ofStreptococcus mutans(MetR),Streptococcus iniae(CpsY), andStreptococcus agalactiae(MtaR) that regulate methionine transport, amino acid metabolism, resistance to neutrophil-mediated killing, and survivalin vivo. Our investigation indicated that CpsY is involved in GAS resistance to innate immune cells of its human host. However, GAS CpsY does not manifest thein vitrophenotypes of its homologs in other streptococcal species. GAS CpsY appears to regulate a small set of genes that is markedly different from the regulons of its homologs. The differential expression of these genes depends on the growth medium, and CpsY modestly influences their expression. The GAS CpsY regulon includes known virulence factors (mntE,speB,spd,nga[spn],prtS[SpyCEP], andsse) and cell surface-associated factors of GAS (emm1,mur1.2,sibA[cdhA], andM5005_Spy0500). Intriguingly, the loss of CpsY in GAS does not result in virulence defects in murine models of infection, suggesting that CpsY function in immune evasion is specific to the human host.

scholarly journals Terminal Deoxynucleotidyl Transferase Is Not Required for Antibody Response to Polysaccharide Vaccines againstStreptococcus pneumoniaeandSalmonella entericaSerovar Typhi

2018 ◽  
Vol 86 (9) ◽  
Author(s):  
Vivek Belde ◽  
Matthew P. Cravens ◽  
Dania Gulandijany ◽  
Justin A. Walker ◽  
Isabel Palomo-Caturla ◽  
...  
Keyword(s):  
Antibody Response ◽  
B Cell ◽  
Salmonella Enterica ◽  
Passive Immunization ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Human Infants ◽  
Content Type ◽  
Serovar Typhimurium

ABSTRACTB cell antigen receptor (BCR) diversity increases by several orders of magnitude due to the action of terminal deoxynucleotidyl transferase (TdT) during V(D)J recombination. Unlike adults, infants have limited BCR diversity, in part due to reduced expression of TdT. Since human infants and young mice respond poorly to polysaccharide vaccines, such as the pneumococcal polysaccharide vaccine Pneumovax23 and Vi polysaccharide (ViPS) ofSalmonella entericaserovar Typhi, we tested the contribution of TdT-mediated BCR diversity in response to these vaccines. We found that TdT+/−and TdT−/−mice generated comparable antibody responses to Pneumovax23 and survivedStreptococcus pneumoniaechallenge. Moreover, passive immunization of B cell-deficient mice with serum from Pneumovax23-immunized TdT+/−or TdT−/−mice conferred protection. TdT+/−and TdT−/−mice generated comparable levels of anti-ViPS antibodies and antibody-dependent, complement-mediated bactericidal activity againstS. Typhiin vitro. To test the protective immunity conferred by ViPS immunizationin vivo, TdT+/−and TdT−/−mice were challenged with a chimericSalmonella entericaserovar Typhimurium strain expressing ViPS, since mice are nonpermissive hosts forS. Typhi infection. Compared to their unimmunized counterparts, immunized TdT+/−and TdT−/−mice challenged with ViPS-expressingS. Typhimurium exhibited a significant reduction in the bacterial burden and liver pathology. These data suggest that the impaired antibody response to the Pneumovax23 and ViPS vaccines in the young is not due to limited TdT-mediated BCR diversification.

scholarly journals Circular RNA CDR1as Exerts Oncogenic Properties Partially through Regulating MicroRNA 641 in Cholangiocarcinoma

2020 ◽  
Vol 40 (15) ◽  
Author(s):  
Dingyang Li ◽  
Zhe Tang ◽  
Zhiqiang Gao ◽  
Pengcheng Shen ◽  
Zhaochen Liu ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Target Genes ◽  
Circular Rna ◽  
Tumor Xenograft ◽  
Mrna Levels ◽  
Cell Behaviors ◽  
Xenograft Growth ◽  
Tumor Xenograft Growth

ABSTRACT It has been found that the circular RNA (circRNA) CDR1as is upregulated in cholangiocarcinoma (CCA) tissues. In this study, we tried to explore the roles of CDR1as in CCA. CDR1as was overexpressed or knocked down in human CCA cells to assess the effects of CDR1as on cell behaviors and tumor xenograft growth. In vitro, the CDR1as level was significantly increased in CCA cell lines. The results showed that CDR1as promoted the cell proliferation, migration, invasion, and activation of the AKT3/mTOR pathway in CCA cells. Moreover, miR-641, a predicted target microRNA (miRNA) of CDR1as, could partially reverse the effects of CDR1as on cell behaviors in CCA cells. Furthermore, CDR1as improved tumor xenograft growth, and it could be attenuated by miR-641 in vivo. Additionally, CDR1as expression was inversely correlated with miR-641 in CCA cells, and miR-641 could directly bind with CDR1as and its target genes, the AKT3 and mTOR genes. Mechanistically, CDR1as could bind with miR-641 and accelerate miR-641 degradation, which possibly leads to the upregulation of the relative mRNA levels of AKT3 and mTOR in RBE cells. In conclusion, our findings indicated that CDR1as might exert oncogenic properties, at least partially, by regulating miR-641 in CCA. CDR1as and miR-641 could be considered therapeutic targets for CCA.

scholarly journals Astaxanthin Treatment Induces Maturation and Functional Change of Myeloid-Derived Suppressor Cells in Tumor-Bearing Mice

Antioxidants ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 350
Author(s):  
Seong Mun Jeong ◽  
Yeon-Jeong Kim
Keyword(s):  
Mhc Class Ii ◽  
Target Genes ◽  
Suppressor Cells ◽  
Functional Change ◽  
Related Factor ◽  
Mrna Levels ◽  
Myeloid Derived Suppressor Cells ◽  
Antitumor Effects

Myeloid-derived suppressor cells (MDSCs) are immature myeloid cells which accumulate in stress conditions such as infection and tumor. Astaxanthin (ATX) is a well-known antioxidant agent and has a little toxicity. It has been reported that ATX treatment induces antitumor effects via regulation of cell signaling pathways, including nuclear factor erythroid-derived 2-related factor 2 (Nrf2) signaling. In the present study, we hypothesized that treatment with ATX might induce maturation of MDSCs and modulate their immunosuppressive activity. Both in vivo and in vitro treatment with ATX resulted in up-regulation of surface markers such as CD80, MHC class II, and CD11c on both polymorphonuclear (PMN)-MDSCs and mononuclear (Mo)-MDSCs. Expression levels of functional mediators involved in immune suppression were significantly reduced, whereas mRNA levels of Nrf2 target genes were increased in ATX-treated MDSCs. In addition, ATX was found to have antioxidant activity reducing reactive oxygen species level in MDSCs. Finally, ATX-treated MDSCs were immunogenic enough to induce cytotoxic T lymphocyte response and contributed to the inhibition of tumor growth. This demonstrates the role of ATX as a regulator of the immunosuppressive tumor environment through induction of differentiation and functional conversion of MDSCs.

scholarly journals Unravelling the Role of the F55 Regulator in the Transition from Lysogeny to UV Induction of Sulfolobus Spindle-Shaped Virus 1

2015 ◽  
Vol 89 (12) ◽  
pp. 6453-6461 ◽  
Author(s):  
Salvatore Fusco ◽  
Qunxin She ◽  
Gabriella Fiorentino ◽  
Simonetta Bartolucci ◽  
Patrizia Contursi
Keyword(s):  
Transcription Factor ◽  
Regulation Of Transcription ◽  
Content Type ◽  
Inducible Promoters ◽  
Host Interaction ◽  
Viral Genes ◽  
Uv Induction ◽  
Differential Affinity

ABSTRACTSulfolobusspindle-shaped virus 1 represents a model for studying virus-host interaction in harsh environments, and it is so far the only member of the familyFuselloviridaethat shows a UV-inducible life cycle. Although the virus has been extensively studied, mechanisms underpinning the maintenance of lysogeny as well as those regulating the UV induction have received little attention. Recently, a novel SSV1 transcription factor, F55, was identified. This factor was able to bindin vitroto several sequences derived from the early and UV-inducible promoters of the SSV1 genome. The location of these binding sites together with the differential affinity of F55 for these sequences led to the hypothesis that this protein might be involved in the maintenance of the SSV1 lysogeny. Here, we report anin vivosurvey of the molecular events occurring at the UV-inducible region of the SSV1 genome, with a focus on the binding profile of F55 before and after the UV irradiation. The binding of F55 to the target promoters correlates with transcription repression, whereas its dissociation is paralleled by transcription activation. Therefore, we propose that F55 acts as a molecular switch for the transcriptional regulation of the early viral genes.IMPORTANCEFunctional genomic studies of SSV1 proteins have been hindered by the lack of similarity with other characterized proteins. As a result, few insights into theirin vivoroles have been gained throughout the last 3 decades. Here, we report the firstin vivoinvestigation of an SSV1 transcription regulator, F55, that plays a key role in the transition from the lysogenic to the induced state of SSV1. We show that F55 regulates the expression of the UV-inducible as well as the early genes. Moreover, the differential affinity of this transcription factor for these targets allows a fine-tuned and temporal coordinated regulation of transcription of viral genes.

GA Binding Protein (GABP) Is Required for Development and Maturation of Myeloid Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 776-776
Author(s):  
Zhongfa Yang ◽  
Alan G. Rosmarin
Keyword(s):  
Cell Cycle ◽  
Transcription Factor ◽  
Target Genes ◽  
Embryonic Stem ◽  
Myeloid Cells ◽  
Transactivation Domain ◽  
Wild Type ◽  
Floxed Allele

Abstract GABP is an ets transcription factor that regulates transcription of key myeloid genes, including CD18 (beta2 leukocyte integrin), neutrophil elastase, lysozyme, and other key mediators of the inflammatory response; it is also known to regulate important cell cycle control genes. GABP consists of two distinct and unrelated proteins that, together, form a functional transcription factor complex. GABPalpha (GABPa) is an ets protein that binds to DNA; it forms a tetrameric complex by recruiting its partner, GABPbeta (GABPb), which contains the transactivation domain. GABPa is a single copy gene in both the human and murine genomes and it is the only protein that can recruit GABPb to DNA. We cloned GABPa from a murine genomic BAC library and prepared a targeting vector in which exon 9 (which encodes the GABPa ets domain) was flanked by loxP (floxed) recombination sites. The targeting construct was electroporated into embryonic stem cells, homologous recombinants were implanted into pseudopregnant mice, heterozygous floxed GABPa mice were identified, and intercrossing yielded expected Mendelian ratios of wild type, heterozygous, and homozygous floxed GABPa mice. Breeding of heterozygous floxed GABPa mice to CMV-Cre mice (which express Cre recombinase in all tissues) yielded expected numbers of hemizygous mice (only one intact GABPa allele), but no nullizygous (GABPa−/−) mice among 64 pups; we conclude that homozygous deletion of GABPa causes an embryonic lethal defect. To determine the effect of GABPa deletion on myeloid cell development, we bred heterozygous and homozygous floxed mice to LysMCre mice, which express Cre only in myeloid cells. These mice had a normal complement of myeloid cells but, unexpectedly, PCR indicated that their Gr1+ myeloid cells retained an intact (undeleted) floxed GABPa allele. We detected similar numbers of in vitro myeloid colonies from bone marrow of wild type, heterozygous floxed, and homozygous floxed progeny of LysMCre matings. However, PCR of twenty individual in vitro colonies from homozygous floxed mice indicated that they all retained an intact floxed allele. Breeding of floxed GABPa/LysMCre mice with hemizygous mice indicated that retention of a floxed allele was not due to incomplete deletion by LysMCre; rather, it appears that only myeloid cells that retain an intact GABPa allele can survive to mature in vitro or in vivo. We prepared murine embryonic fibroblasts from homozygous floxed mice and efficiently deleted GABPa in vitro. We found striking abnormalities in proliferation and G1/S phase arrest. We used quantitative RT-PCR to identify mechanisms that account for the altered growth of GABPa null cells. We found dramatically reduced expression of known GABP target genes that regulate DNA synthesis and cell cycle that appear to account for the proliferative defect. We conclude that GABPa is required for growth and maturation of myeloid cells and we identified downstream targets that may account for their failure to proliferate and mature in vitro and in vivo.

scholarly journals EspA, an Orphan Hybrid Histidine Protein Kinase, Regulates the Timing of Expression of Key Developmental Proteins of Myxococcus xanthus

2008 ◽  
Vol 190 (13) ◽  
pp. 4416-4426 ◽  
Author(s):  
Penelope I. Higgs ◽  
Sakthimala Jagadeesan ◽  
Petra Mann ◽  
David R. Zusman
Keyword(s):  
Myxococcus Xanthus ◽  
Transcriptional Regulator ◽  
Phosphoryl Group ◽  
Protein Accumulation ◽  
Developmental Gene Expression ◽  
Developmental Program ◽  
Expression Of Genes ◽  
Early Expression

ABSTRACT Myxococcus xanthus undergoes a complex starvation-induced developmental program that results in cells forming multicellular fruiting bodies by aggregating into mounds and then differentiating into spores. This developmental program requires at least 72 h and is mediated by a temporal cascade of gene regulators in response to intra- and extracellular signals. espA mutants, encoding an orphan hybrid histidine kinase, alter the timing of this developmental program, greatly accelerating developmental progression. Here, we characterized EspA and demonstrated that it autophosphorylates in vitro on the conserved histidine residue and then transfers the phosphoryl group to the conserved aspartate residue in the associated receiver domain. The conserved histidine and aspartate residues were both required for EspA function in vivo. Analysis of developmental gene expression and protein accumulation in espA mutants indicated that the expression of the A-signal-dependent spi gene was not affected but that the MrpC transcriptional regulator accumulated earlier, resulting in earlier expression of its target, the FruA transcriptional regulator. Early expression of FruA correlated with acceleration of both the aggregation and sporulation branches of the developmental program, as monitored by early methylation of the FrzCD chemosensory receptor and early expression of the sporulation-specific dev and Mxan_3227 (Ω7536) genes. These results show that EspA plays a key role in the timing of expression of genes necessary for progression of cells through the developmental program.

scholarly journals Oncogenic hijacking of a developmental transcription factor evokes therapeutic vulnerability for ROS-induction in Ewing sarcoma

2019 ◽  
Author(s):  
Aruna Marchetto ◽  
Shunya Ohmura ◽  
Martin F. Orth ◽  
Jing Li ◽  
Fabienne S. Wehweck ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Stem Cells ◽  
Transcription Factor ◽  
Ewing Sarcoma ◽  
Target Genes ◽  
Transcriptome Profiling ◽  
Oxygen Species ◽  
Ets Family

ABSTRACTEwing sarcoma (EwS) is an aggressive childhood cancer likely originating from mesenchymal stem cells or osteo-chondrogenic progenitors. It is characterized by fusion oncoproteins involving EWSR1 and variable members of the ETS-family of transcription factors (in 85% FLI1). EWSR1-FLI1 can induce target genes by using GGAA-microsatellites (mSats) as enhancers.Here, we show that EWSR1-FLI1 hijacks the developmental transcription factor SOX6 – a physiological driver of proliferation of osteo-chondrogenic progenitors – by binding to an intronic GGAA-mSat, which promotes EwS growthin vitroandin vivo. Through integration of transcriptome-profiling, published drug-screening data, and functionalin vitroandin vivoexperiments, we discovered that SOX6 interferes with the antioxidant system resulting in constitutively elevated reactive oxygen species (ROS) levels that create a therapeutic vulnerability toward the ROS-inducing drug Elesclomol.Collectively, our results exemplify how aberrant activation of a developmental transcription factor by a dominant oncogene can promote malignancy, but provide opportunities for targeted therapy.

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