scholarly journals Synthetic gene regulatory networks in the opportunistic human pathogen Streptococcus pneumoniae

2019 ◽  
Author(s):  
Robin A. Sorg ◽  
Clement Gallay ◽  
Jan-Willem Veening
Keyword(s):  
Gene Expression ◽  
Streptococcus Pneumoniae ◽  
Regulatory Networks ◽  
Expression Patterns ◽  
Combinatorial Libraries ◽  
Regulatory Elements ◽  
Expression Control ◽  
Gene Expression Control

AbstractStreptococcus pneumoniae can cause disease in various human tissues and organs, including the ear, the brain, the blood and the lung, and thus in highly diverse and dynamic environments. It is challenging to study how pneumococci control virulence factor expression, because cues of natural environments and the presence of an immune system are difficult to simulate in vitro. Here, we apply synthetic biology methods to reverse-engineer gene expression control in S. pneumoniae. A selection platform is described that allows for straightforward identification of transcriptional regulatory elements out of combinatorial libraries. We present TetR- and LacI-regulated promoters that show expression ranges of four orders of magnitude. Based on these promoters, regulatory networks of higher complexity are assembled, such as logic AND and IMPLY gates. Finally, we demonstrate single-copy genome-integrated toggle switches that give rise to bimodal population distributions. The tools described here can be used to mimic complex expression patterns, such as the ones found for pneumococcal virulence factors, paving the way for in vivo investigations of the importance of gene expression control on the pathogenicity of S. pneumoniae.

scholarly journals Synthetic gene-regulatory networks in the opportunistic human pathogenStreptococcus pneumoniae

2020 ◽  
Vol 117 (44) ◽  
pp. 27608-27619 ◽  
Author(s):  
Robin A. Sorg ◽  
Clement Gallay ◽  
Laurye Van Maele ◽  
Jean-Claude Sirard ◽  
Jan-Willem Veening
Keyword(s):  
Gene Expression ◽  
Virulence Factor ◽  
Gene Regulatory Networks ◽  
Regulatory Networks ◽  
Combinatorial Libraries ◽  
Regulatory Elements ◽  
Synthetic Gene ◽  
Expression Control ◽  
Gene Expression Control ◽  
Gene Regulatory

Streptococcus pneumoniaecan cause disease in various human tissues and organs, including the ear, the brain, the blood, and the lung, and thus in highly diverse and dynamic environments. It is challenging to study how pneumococci control virulence factor expression, because cues of natural environments and the presence of an immune system are difficult to simulate in vitro. Here, we apply synthetic biology methods to reverse-engineer gene expression control inS. pneumoniae. A selection platform is described that allows for straightforward identification of transcriptional regulatory elements out of combinatorial libraries. We present TetR- and LacI-regulated promoters that show expression ranges of four orders of magnitude. Based on these promoters, regulatory networks of higher complexity are assembled, such as logic AND gates and IMPLY gates. We demonstrate single-copy genome-integrated toggle switches that give rise to bimodal population distributions. The tools described here can be used to mimic complex expression patterns, such as the ones found for pneumococcal virulence factors. Indeed, we were able to rewire gene expression of the capsule operon, the main pneumococcal virulence factor, to be externally inducible (YES gate) or to act as an IMPLY gate (only expressed in absence of inducer). Importantly, we demonstrate that these synthetic gene-regulatory networks are functional in an influenza A virus superinfection murine model of pneumonia, paving the way for in vivo investigations of the importance of gene expression control on the pathogenicity ofS. pneumoniae.

scholarly journals First insights into the molecular basis association between promoter polymorphisms of the IL1B gene and Helicobacter pylori infection in the Sudanese population: computational approach

2020 ◽  
Author(s):  
Abeer Babiker Idris ◽  
Einas Babiker Idris ◽  
Amany Eltayib Ataelmanan ◽  
Ali Elbagir Ali Mohamed ◽  
Bashir M. Osman Arbab ◽  
...  
Keyword(s):  
Gene Expression ◽  
In Silico ◽  
Expression Patterns ◽  
Regulatory Region ◽  
Regulatory Elements ◽  
Computer Algorithms ◽  
Promoter Polymorphisms ◽  
H Pylori

Abstract Background: Helicobacter pylori (H. pylori) infects nearly half of the world’s population with a variation in incidence among different geographic regions. Genetic variants in the promoter regions of the IL1B gene can affect cytokine expression and creates a condition of hypoacidity which favors the survival and colonization of H. pylori. Therefore, the aim of this study was to characterize the polymorphic sites in the 5’- region [-687_+297] of IL1B in H. pylori infection using in silico tools.Results: A total of five nucleotide variations were detected in the 5’-regulatory region [-687_+297] of IL1B which led to the addition or alteration of transcription factor binding sites (TFBSs) or composite regulatory elements (CEs). Genotyping of IL1B-31 C>T revealed a significant association between -31T and susceptibility to H. pylori infection in the studied population (P=0.0363). Comparative analysis showed conservation rates of IL1B upstream [−368_+10] region above 70% in chimpanzee, rhesus monkey, a domesticated dog, cow and rat.Conclusions: In H. pylori-infected patients, three detected SNPs (-338, -155 and -31) located in the IL1B promoter were predicted to alter TFBSs and CE, which might affect the gene expression. These in silico predictions provide insight for further experimental in vitro and in vivo studies of the regulation of IL1B expression and its relationship to H. pylori infection. However, the recognition of regulatory motifs by computer algorithms is fundamental for understanding gene expression patterns.

68 GENE EXPRESSION COMPARISONS BETWEEN BOVINE IN VIVO AND CLONED EMBRYOS PRODUCED BY THREE DIFFERENT METHODS

2006 ◽  
Vol 18 (2) ◽  
pp. 142
Author(s):  
N. Ruddock ◽  
K. Wilson ◽  
M. Cooney ◽  
R. Tecirlioglu ◽  
V. Hall ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chromatin Remodeling ◽  
Nuclear Transfer ◽  
Expression Patterns ◽  
Experimental Models ◽  
Gene Expression Patterns ◽  
Imprinted Genes ◽  
Mammalian Embryo

Developmental pathways in the mammalian embryo are profoundly influenced by the epigenetic interaction of the environment and the genome. Loss of epigenetic control has been implicated in aberrant gene expression and altered imprinting patterns with consequence to the physiology and viability of the conceptus. Bovine somatic cell nuclear transfer (SCNT) is contingent on in vitro culture, and both SCNT and culture conditions are known to induce changes in embryonic gene expression patterns. Using these experimental models, this study compared gene expression of Day 7 cloned blastocysts created from three different SCNT protocols using the same cell line, with Day 7 in vivo blastocysts to elucidate mechanisms responsible for variations in phenotypic outcomes. SCNT methods included: (1) traditional SCNT by subzonal injection (SI); (2) handmade cloning (HMC); and (3) modified serial nuclear transfer (SNT), developed within the group. Four imprinted genes (Grb10, Ndn, Nnat, and Ube3a), four chromatin remodeling genes (Cbx1, Cbx3, Smarca4, and Smarcb1) and two genes implicated in polycystic liver disease (Prkcsh and Sec63) were analyzed in single blastocysts from each treatment (n = 5). All blastocysts expressed Actin, Oct-4 and Ifn-tau. All genes were sequence verified. Several genes were expressed ubiquitously across all groups, including Ndn, Ube3a, Cbx1, Cbx3, and Smarcb1. Interestingly, Grb10 was not expressed in two HMCs and one SNT blastocyst. Nnat was weakly expressed in one in vivo blastocyst and in the majority of cloned blastocysts in all groups. Prkcsh and Sec63 were expressed in all but one HMC blastocyst. While gene expression patterns were mostly maintained following SCNT, the imprinted genes Nnat and Grb10 showed instances of differential or abnormal expression in SCNT embryos. The chromatin remodeling genes were maintained in all SCNT treatments. Prkcsh and Sec63 were both absent in one HMC blastocyst, with implications for liver dysfunction, a condition previously reported in abnormal cloned offspring. The variable mRNA expression following SCNT provides an insight into genetic and environmental factors controlling implantation, placentation, organ formation, and fetal growth.

scholarly journals Transcriptional Regulation in Ebola Virus: Effects of Gene Border Structure and Regulatory Elements on Gene Expression and Polymerase Scanning Behavior

2015 ◽  
Vol 90 (4) ◽  
pp. 1898-1909 ◽  
Author(s):  
Kristina Brauburger ◽  
Yannik Boehmann ◽  
Verena Krähling ◽  
Elke Mühlberger
Keyword(s):  
Gene Expression ◽  
Ebola Virus ◽  
Rna Virus ◽  
Regulatory Elements ◽  
Minor Role ◽  
Transcript Levels ◽  
Reading Frame ◽  
Noncoding Regions ◽  
Expression Control ◽  
Gene Expression Control

ABSTRACTThe highly pathogenic Ebola virus (EBOV) has a nonsegmented negative-strand (NNS) RNA genome containing seven genes. The viral genes either are separated by intergenic regions (IRs) of variable length or overlap. The structure of the EBOV gene overlaps is conserved throughout all filovirus genomes and is distinct from that of the overlaps found in other NNS RNA viruses. Here, we analyzed how diverse gene borders and noncoding regions surrounding the gene borders influence transcript levels and govern polymerase behavior during viral transcription. Transcription of overlapping genes in EBOV bicistronic minigenomes followed the stop-start mechanism, similar to that followed by IR-containing gene borders. When the gene overlaps were extended, the EBOV polymerase was able to scan the template in an upstream direction. This polymerase feature seems to be generally conserved among NNS RNA virus polymerases. Analysis of IR-containing gene borders showed that the IR sequence plays only a minor role in transcription regulation. Changes in IR length were generally well tolerated, but specific IR lengths led to a strong decrease in downstream gene expression. Correlation analysis revealed that these effects were largely independent of the surrounding gene borders. Each EBOV gene contains exceptionally long untranslated regions (UTRs) flanking the open reading frame. Our data suggest that the UTRs adjacent to the gene borders are the main regulators of transcript levels. A highly complex interplay between the differentcis-acting elements to modulate transcription was revealed for specific combinations of IRs and UTRs, emphasizing the importance of the noncoding regions in EBOV gene expression control.IMPORTANCEOur data extend those from previous analyses investigating the implication of noncoding regions at the EBOV gene borders for gene expression control. We show that EBOV transcription is regulated in a highly complex yet not easily predictable manner by a set of interactingcis-active elements. These findings are important not only for the design of recombinant filoviruses but also for the design of other replicon systems widely used as surrogate systems to study the filovirus replication cycle under low biosafety levels. Insights into the complex regulation of EBOV transcription conveyed by noncoding sequences will also help to interpret the importance of mutations that have been detected within these regions, including in isolates of the current outbreak.

scholarly journals Hepatic gene expression patterns in thyroid hormone-treated hypothyroid rats

2003 ◽  
Vol 31 (2) ◽  
pp. 291-303 ◽  
Author(s):  
JM Weitzel ◽  
S Hamann ◽  
M Jauk ◽  
M Lacey ◽  
A Filbry ◽  
...  
Keyword(s):  
Gene Expression ◽  
Thyroid Hormone ◽  
Expression Patterns ◽  
Regulatory Elements ◽  
Activation Mechanism ◽  
Gene Expression Patterns ◽  
Peroxisome Proliferator ◽  
Gene Promoters ◽  
Protein Levels

Thyroid hormone (T3) is essential for normal development, differentiation and metabolic balance. We have performed DNA microarray experiments using hepatic RNA from hypothyroid and T3-treated hypothyroid rats in order to characterize T3-induced gene expression patterns after various time points (6, 24 and 48 h after the administration of the hormone). Sixty-two of 4608 different genes displayed a reproducible T3-response, and cluster analysis divided these differentially regulated genes into six expression patterns. Thirty-six genes were not significantly regulated within the first 24 h. Transient transfection experiments of eight late-induced gene promoters failed to detect a thyroid hormone response element within their regulatory elements, suggesting an indirect activation mechanism(s). In search for an intermediate factor of T3 action, we examined whether various rather ubiquitous transcription factors, peroxisome proliferator-activated receptors (PPARs) and coactivators of the PPARgamma coactivator 1 family (PGC-1) are regulated by T3. Only PPARgamma and PERC/PGC-1beta exhibit a significant T3-response within the first 6 h after treatment, identifying these factors as candidate components for mediating the late-induced expression pattern. Regulation of early-induced genes within the first 6 h after administration of T3 on transcript levels correlates with altered protein levels after 24 and 48 h in vivo.

scholarly journals tRNA-Derived Fragments Target the Ribosome and Function as Regulatory Non-Coding RNA inHaloferax volcanii

Archaea ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Jennifer Gebetsberger ◽  
Marek Zywicki ◽  
Andrea Künzi ◽  
Norbert Polacek
Keyword(s):  
Gene Expression ◽  
Regulatory Networks ◽  
Ribosomal Subunit ◽  
Fine Tuning ◽  
Transferase Activity ◽  
Dependent Manner ◽  
Efficient Manner ◽  
Stress Dependent

Nonprotein coding RNA (ncRNA) molecules have been recognized recently as major contributors to regulatory networks in controlling gene expression in a highly efficient manner. These RNAs either originate from their individual transcription units or are processing products from longer precursor RNAs. For example, tRNA-derived fragments (tRFs) have been identified in all domains of life and represent a growing, yet functionally poorly understood, class of ncRNA candidates. Here we present evidence that tRFs from the halophilic archaeonHaloferax volcaniidirectly bind to ribosomes. In the presented genomic screen of the ribosome-associated RNome, a 26-residue-long fragment originating from the 5′ part of valine tRNA was by far the most abundant tRF. The Val-tRF is processed in a stress-dependent manner and was found to primarily target the small ribosomal subunitin vitroandin vivo. As a consequence of ribosome binding, Val-tRF reduces protein synthesis by interfering with peptidyl transferase activity. Therefore this tRF functions as ribosome-bound small ncRNA capable of regulating gene expression inH. volcaniiunder environmental stress conditions probably by fine tuning the rate of protein production.

scholarly journals Developmental and molecular correlates of bovine preimplantation embryos

Reproduction ◽  
2006 ◽  
Vol 131 (5) ◽  
pp. 895-904 ◽  
Author(s):  
Hakan Sagirkaya ◽  
Muge Misirlioglu ◽  
Abdullah Kaya ◽  
Neal L First ◽  
John J Parrish ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methyltransferase ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Blastocyst Stage ◽  
Culture Conditions ◽  
Preimplantation Embryos ◽  
Developmental Potential

Expression of embryonic genes is altered in different culture conditions, which influence developmental potential both during preimplantation and fetal development. The objective of this study was to define the effects of culture conditions on: bovine embryonic development to blastocyst stage, blastocyst cell number, apoptosis and expression patterns of a panel of developmentally important genes. Bovine embryos were culturedin vitroin three culture media containing amino acids, namely potassium simplex optimization medium (KSOMaa), Charles Rosenkrans 1 (CR1aa) and synthetic oviductal fluid (SOFaa). Apoptosis in blastocysts was determined by TUNEL assay and expression profiles of developmentally important genes were assayed by real-time PCR.In vivo-produced bovine blastocysts were used as controls for experiments determining gene expression patterns. While the cleavage rates did not differ, embryos cultured in SOFaa had higher rates of development to blastocyst stage (P< 0.05). Mean cell numbers and percentages of apoptotic cells per blastocyst did not differ among the groups. Expression of the heat shock protein 70 (Hsp70) gene was significantly up-regulated in both CR1aa and KSOMaa when compared with SOFaa (P< 0.001). DNA methyltransferase 3a (Dnmt3a) expression was higher in embryos cultured in CR1aa than in those cultured in SOFaa (P< 0.001). Expression of interferon tau (IF-τ) and insulin-like growth factor II receptor (Igf-2r) genes was significantly up-regulated in KSOMaa when compared with CR1aa (P< 0.001). Gene expression did not differ betweenin vivo-derived blastocysts and theirin vitro-derived counterparts. In conclusion, SOFaa supports higher development to blastocyst stage than KSOMaa and CR1aa, and the culture conditions influence gene expression.

scholarly journals Mapping gene regulatory networks of primary CD4+T cells using single-cell genomics and genome engineering

2019 ◽  
Author(s):  
Rachel E. Gate ◽  
Min Cheol Kim ◽  
Andrew Lu ◽  
David Lee ◽  
Eric Shifrut ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
Gene Regulatory Networks ◽  
Regulatory Networks ◽  
Genome Engineering ◽  
Regulatory Elements ◽  
Mapping Gene ◽  
Gene Regulatory ◽  
Novel Interactions

AbstractGene regulatory programs controlling the activation and polarization of CD4+T cells are incompletely mapped and the interindividual variability in these programs remain unknown. We sequenced the transcriptomes of ~160k CD4+T cells from 9 donors following pooled CRISPR perturbation targeting 140 regulators. We identified 134 regulators that affect T cell functionalization, includingIRF2as a positive regulator of Th2polarization. Leveraging correlation patterns between cells, we mapped 194 pairs of interacting regulators, including known (e.g.BATFandJUN) and novel interactions (e.g.ETS1andSTAT6). Finally, we identified 80 natural genetic variants with effects on gene expression, 48 of which are modified by a perturbation. In CD4+T cells, CRISPR perturbations can influencein vitropolarization and modify the effects oftransandcisregulatory elements on gene expression.

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