Differential Target Gene Activation by the Staphylococcus aureus Two-Component System saeRS

ABSTRACT The saePQRS system of Staphylococcus aureus controls the expression of major virulence factors and encodes a histidine kinase (SaeS), a response regulator (SaeR), a membrane protein (SaeQ), and a lipoprotein (SaeP). The widely used strain Newman is characterized by a single amino acid change in the sensory domain of SaeS (Pro18 in strain Newman [SaeSP], compared with Leu18 in other strains [SaeSL]). SaeSP determines activation of the class I sae target genes (coa, fnbA, eap, sib, efb, fib, sae), which are highly expressed in strain Newman. In contrast, class II target genes (hla, hlb, cap) are not sensitive to the SaeS polymorphism. The SaeSL allele (saeSL ) is dominant over the SaeSP allele, as shown by single-copy integration of saePQRSL in strain Newman, which results in severe repression of class I target genes. The differential effect on target gene expression is explained by different requirements for SaeR phosphorylation. From an analysis of saeS deletion strains and strains with mutated SaeR phosphorylation sites, we concluded that a high level of SaeR phosphorylation is required for activation of class I target genes. However, a low level of SaeR phosphorylation, which can occur independent of SaeS, is sufficient to activate class II target genes. Using inducible saeRS constructs, we showed that the expression of both types of target genes is independent of the saeRS dosage and that the typical growth phase-dependent gene expression pattern is not driven by SaeRS.

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FLT3ITD Target Enhancers Are Primed but Inaccessible in Fetal Hematopoietic Progenitors

Blood ◽

10.1182/blood-2019-126201 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1228-1228

Author(s):

Yanan Li ◽

Riddhi M Patel ◽

Emily Casey ◽

Jeffrey A. Magee

Keyword(s):

Gene Expression ◽

Transcription Factors ◽

Target Gene ◽

Target Genes ◽

Conflicts Of Interest ◽

Gene Activation ◽

Chromatin Accessibility ◽

Luciferase Reporter ◽

Enhancer Activity ◽

Target Gene Expression

The FLT3 Internal Tandem Duplication (FLT3ITD) is common somatic mutation in acute myeloid leukemia (AML). We have previously shown that FLT3ITD fails to induce changes in HSC self-renewal, myelopoiesis and leukemogenesis during fetal stages of life. FLT3ITD signal transduction pathways are hyperactivated in fetal progenitors, but FLT3ITD target genes are not. This suggests that postnatal-specific transcription factors may be required to help induce FLT3ITD target gene expression. Alternatively, repressive histone modifications may impose a barrier to FLT3ITD target gene activation in fetal HPCs that is relaxed during postnatal development. To resolve these possibilities, we used ATAC-seq, as well as H3K4me1, H3K27ac and H3K27me3 ChIP-seq, to identify cis-elements that putatively control FLT3ITD target gene expression in fetal and adult hematopoietic progenitor cells (HPCs). We identified many enhancer elements (ATAC-seq peaks with H3K4me1 and H3K27ac) that exhibited increased chromatin accessibility and activity in FLT3ITD adult HPCs relative to wild type adult HPCs. These elements were enriched near FLT3ITD target genes. HOMER analysis showed enrichment for STAT5, ETS, RUNX1 and IRF binding motifs within the FLT3ITD target enhancers, but motifs for temporally dynamic transcription factors were not identified. We cloned a subset of the enhancers and confirmed that they could synergize with their promoter to activate a luciferase reporter. For representative enhancers, STAT5 binding sites were required to activate the enhancer - as anticipated - and RUNX1 repressed enhancer activity. We tested whether accessibility or priming changed between fetal and adult stages of HPC development. FLT3ITD-dependent changes in chromatin accessibility were not observed in fetal HPCs, though the enhancers were primed early in development as evidenced by the presence of H3K4me1. Repressive H3K27me3 were not present at FLT3ITD target enhancers in either or adult HPCs. The data show that FLT3ITD target enhancers are demarcated early in hematopoietic development, long before they become responsive to FLT3ITD signaling. Repressive marks do not appear to create an epigenetic barrier to enhancer activation in the fetal stage. Instead, age-specific transcription factors are likely required to pioneer enhancer elements so that they can respond to STAT5 and other FLT3ITD effectors. Disclosures No relevant conflicts of interest to declare.

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The BMP signaling gradient is interpreted through concentration thresholds in dorsal–ventral axial patterning

PLoS Biology ◽

10.1371/journal.pbio.3001059 ◽

2021 ◽

Vol 19 (1) ◽

pp. e3001059

Author(s):

Hannah Greenfeld ◽

Jerome Lin ◽

Mary C. Mullins

Keyword(s):

Gene Expression ◽

Single Cell ◽

Target Gene ◽

Target Genes ◽

Gene Activation ◽

Spatial Relationship ◽

Bmp Signaling ◽

Target Gene Expression ◽

Gradient Slope ◽

Distinct Cell

Bone Morphogenetic Protein (BMP) patterns the dorsal–ventral (DV) embryonic axis in all vertebrates, but it is unknown how cells along the DV axis interpret and translate the gradient of BMP signaling into differential gene activation that will give rise to distinct cell fates. To determine the mechanism of BMP morphogen interpretation in the zebrafish gastrula, we identified 57 genes that are directly activated by BMP signaling. By using Seurat analysis of single-cell RNA sequencing (scRNA-seq) data, we found that these genes are expressed in at least 3 distinct DV domains of the embryo. We distinguished between 3 models of BMP signal interpretation in which cells activate distinct gene expression through interpretation of thresholds of (1) the BMP signaling gradient slope; (2) the BMP signal duration; or (3) the level of BMP signal activation. We tested these 3 models using quantitative measurements of phosphorylated Smad5 (pSmad5) and by examining the spatial relationship between BMP signaling and activation of different target genes at single-cell resolution across the embryo. We found that BMP signaling gradient slope or BMP exposure duration did not account for the differential target gene expression domains. Instead, we show that cells respond to 3 distinct levels of BMP signaling activity to activate and position target gene expression. Together, we demonstrate that distinct pSmad5 threshold levels activate spatially distinct target genes to pattern the DV axis.

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Identification of homeotic target genes in Drosophila melanogaster including nervy, a proto-oncogene homologue.

Genetics ◽

10.1093/genetics/140.2.573 ◽

1995 ◽

Vol 140 (2) ◽

pp. 573-586 ◽

Cited By ~ 11

Author(s):

P G Feinstein ◽

K Kornfeld ◽

D S Hogness ◽

R S Mann

Keyword(s):

Gene Expression ◽

Target Gene ◽

Target Genes ◽

Early Stage ◽

Gene Expression Pattern ◽

Morphological Characteristics ◽

Subtractive Hybridization ◽

Homeotic Genes ◽

Target Gene Expression ◽

Downstream Target

Abstract In Drosophila, the specific morphological characteristics of each segment are determined by the homeotic genes that regulate the expression of downstream target genes. We used a subtractive hybridization procedure to isolate activated target genes of the homeotic gene Ultrabithorax (Ubx). In addition, we constructed a set of mutant genotypes that measures the regulatory contribution of individual homeotic genes to a complex target gene expression pattern. Using these mutants, we demonstrate that homeotic genes can regulate target gene expression at the start of gastrulation, suggesting a previously unknown role for the homeotic genes at this early stage. We also show that, in abdominal segments, the levels of expression for two target genes increase in response to high levels of Ubx, demonstrating that the normal down-regulation of Ubx in these segments is functional. Finally, the DNA sequence of cDNAs for one of these genes predicts a protein that is similar to a human proto-oncogene involved in acute myeloid leukemias. These results illustrate potentially general rules about the homeotic control of target gene expression and suggest that subtractive hybridization can be used to isolate interesting homeotic target genes.

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The EAR Motif in the Arabidopsis MADS Transcription Factor AGAMOUS-Like 15 Is Not Necessary to Promote Somatic Embryogenesis

Plants ◽

10.3390/plants10040758 ◽

2021 ◽

Vol 10 (4) ◽

pp. 758

Author(s):

Sanjay Joshi ◽

Christian Keller ◽

Sharyn E. Perry

Keyword(s):

Gene Expression ◽

Somatic Embryogenesis ◽

Target Gene ◽

Target Genes ◽

Domain Family ◽

Binding Factor ◽

Ear Motif ◽

Carboxyl Terminal ◽

Responsive Element ◽

Carboxy Terminal

AGAMOUS-like 15 (AGL15) is a member of the MADS domain family of transcription factors (TFs) that can directly induce and repress target gene expression, and for which promotion of somatic embryogenesis (SE) is positively correlated with accumulation. An ethylene-responsive element binding factor-associated amphiphilic repression (EAR) motif of form LxLxL within the carboxyl-terminal domain of AGL15 was shown to be involved in repression of gene expression. Here, we examine whether AGL15′s ability to repress gene expression is needed to promote SE. While a form of AGL15 where the LxLxL is changed to AxAxA can still promote SE, another form with a strong transcriptional activator at the carboxy-terminal end, does not promote SE and, in fact, is detrimental to SE development. Select target genes were examined for response to the different forms of AGL15.

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On the way toward regulatable expression systems in acetic acid bacteria: target gene expression and use cases

Applied Microbiology and Biotechnology ◽

10.1007/s00253-021-11269-z ◽

2021 ◽

Author(s):

Philipp Moritz Fricke ◽

Angelika Klemm ◽

Michael Bott ◽

Tino Polen

Keyword(s):

Gene Expression ◽

Acetic Acid ◽

Literature Search ◽

Target Gene ◽

Target Genes ◽

Recombinant Dna ◽

Acetic Acid Bacteria ◽

Homoserine Lactone ◽

Expression Systems ◽

Target Gene Expression

Abstract Acetic acid bacteria (AAB) are valuable biocatalysts for which there is growing interest in understanding their basics including physiology and biochemistry. This is accompanied by growing demands for metabolic engineering of AAB to take advantage of their properties and to improve their biomanufacturing efficiencies. Controlled expression of target genes is key to fundamental and applied microbiological research. In order to get an overview of expression systems and their applications in AAB, we carried out a comprehensive literature search using the Web of Science Core Collection database. The Acetobacteraceae family currently comprises 49 genera. We found overall 6097 publications related to one or more AAB genera since 1973, when the first successful recombinant DNA experiments in Escherichia coli have been published. The use of plasmids in AAB began in 1985 and till today was reported for only nine out of the 49 AAB genera currently described. We found at least five major expression plasmid lineages and a multitude of further expression plasmids, almost all enabling only constitutive target gene expression. Only recently, two regulatable expression systems became available for AAB, an N-acyl homoserine lactone (AHL)-inducible system for Komagataeibacter rhaeticus and an l-arabinose-inducible system for Gluconobacter oxydans. Thus, after 35 years of constitutive target gene expression in AAB, we now have the first regulatable expression systems for AAB in hand and further regulatable expression systems for AAB can be expected. Key points • Literature search revealed developments and usage of expression systems in AAB. • Only recently 2 regulatable plasmid systems became available for only 2 AAB genera. • Further regulatable expression systems for AAB are in sight.

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Regulation of mouse CYP1A1 gene expression by dioxin: requirement of two cis-acting elements during induction

Molecular and Cellular Biology ◽

10.1128/mcb.9.6.2378-2386.1989 ◽

1989 ◽

Vol 9 (6) ◽

pp. 2378-2386

Author(s):

L A Neuhold ◽

Y Shirayoshi ◽

K Ozato ◽

J E Jones ◽

D W Nebert

Keyword(s):

Gene Expression ◽

Simian Virus 40 ◽

Class Ii ◽

Simian Virus ◽

Class I ◽

Ah Receptor ◽

Class Iii ◽

Cis Acting ◽

Cyp1a1 Gene ◽

Sv40 Dna

The mouse cytochrome P1450 (CYP1A1) gene is responsible for the metabolism of numerous carcinogens and toxic chemicals. Induction by the environmental contaminant tetrachlorodibenzo-p-dioxin (TCDD) requires a functional aromatic hydrocarbon (Ah) receptor. We examined the 5'-flanking region of the CYP1A1 gene in mouse hepatoma Hepa-1 wild-type cells and a mutant line having a defect in chromatin binding of the TCDD-receptor complex. We identified two cis-acting elements (distal, -1071 to -901 region; proximal, -245 to -50 region) required for constitutive and TCDD-inducible CYP1A1 gene expression. Three classes of DNA-protein complexes binding to the distal element were identified: class I, found only in the presence of TCDD and a functional Ah receptor, that was heat labile and not competed against by simian virus 40 (SV40) early promoter DNA; class II, consisting of at least three constitutive complexes that were heat stable and bound to SV40 DNA; and class III, composed of at least three constitutive complexes that were thermolabile and were not competed against by SV40 DNA. Essential contacts for these proteins were centered at -993 to -990 for the class I complex, -987, -986, or both for the class II complexes, and -938 to -927 for the class III complexes. The proximal element was absolutely essential for both constitutive and TCDD-inducible CYP1A1 gene expression, and at least two constitutive complexes bound to this region. These data are consistent with the proximal element that binds proteins being necessary but not sufficient for inducible gene expression; interaction of these proteins with those at the distal element was found to be required for full CYP1A1 induction by TCDD.

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Elucidation of Regulatory Modes for Five Two-Component Systems in Escherichia coli Reveals Novel Relationships

mSystems ◽

10.1128/msystems.00980-20 ◽

2020 ◽

Vol 5 (6) ◽

Author(s):

Kumari Sonal Choudhary ◽

Julia A. Kleinmanns ◽

Katherine Decker ◽

Anand V. Sastry ◽

Ye Gao ◽

...

Keyword(s):

Gene Expression ◽

Escherichia Coli ◽

Target Gene ◽

Target Genes ◽

Rna Seq ◽

Content Type ◽

E Coli ◽

Component Systems ◽

Two Component ◽

Two Component Systems

ABSTRACT Escherichia coli uses two-component systems (TCSs) to respond to environmental signals. TCSs affect gene expression and are parts of E. coli’s global transcriptional regulatory network (TRN). Here, we identified the regulons of five TCSs in E. coli MG1655: BaeSR and CpxAR, which were stimulated by ethanol stress; KdpDE and PhoRB, induced by limiting potassium and phosphate, respectively; and ZraSR, stimulated by zinc. We analyzed RNA-seq data using independent component analysis (ICA). ChIP-exo data were used to validate condition-specific target gene binding sites. Based on these data, we do the following: (i) identify the target genes for each TCS; (ii) show how the target genes are transcribed in response to stimulus; and (iii) reveal novel relationships between TCSs, which indicate noncognate inducers for various response regulators, such as BaeR to iron starvation, CpxR to phosphate limitation, and PhoB and ZraR to cell envelope stress. Our understanding of the TRN in E. coli is thus notably expanded. IMPORTANCE E. coli is a common commensal microbe found in the human gut microenvironment; however, some strains cause diseases like diarrhea, urinary tract infections, and meningitis. E. coli’s two-component systems (TCSs) modulate target gene expression, especially related to virulence, pathogenesis, and antimicrobial peptides, in response to environmental stimuli. Thus, it is of utmost importance to understand the transcriptional regulation of TCSs to infer bacterial environmental adaptation and disease pathogenicity. Utilizing a combinatorial approach integrating RNA sequencing (RNA-seq), independent component analysis, chromatin immunoprecipitation coupled with exonuclease treatment (ChIP-exo), and data mining, we suggest five different modes of TCS transcriptional regulation. Our data further highlight noncognate inducers of TCSs, which emphasizes the cross-regulatory nature of TCSs in E. coli and suggests that TCSs may have a role beyond their cognate functionalities. In summary, these results can lead to an understanding of the metabolic capabilities of bacteria and correctly predict complex phenotype under diverse conditions, especially when further incorporated with genome-scale metabolic models.

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Position β57 of I-Ag7 controls early anti-insulin responses in NOD mice, linking an MHC susceptibility allele to type 1 diabetes onset

Science Immunology ◽

10.1126/sciimmunol.aaw6329 ◽

2019 ◽

Vol 4 (38) ◽

pp. eaaw6329 ◽

Cited By ~ 9

Author(s):

Louis Gioia ◽

Marie Holt ◽

Anne Costanzo ◽

Siddhartha Sharma ◽

Brian Abe ◽

...

Keyword(s):

T Cells ◽

Type 1 Diabetes ◽

Disease Onset ◽

Insulin Response ◽

Nod Mice ◽

Class Ii ◽

Single Amino Acid ◽

Specific Gene ◽

Single Amino Acid Change

The class II region of the major histocompatibility complex (MHC) locus is the main contributor to the genetic susceptibility to type 1 diabetes (T1D). The loss of an aspartic acid at position 57 of diabetogenic HLA-DQβ chains supports this association; this single amino acid change influences how TCRs recognize peptides in the context of HLA-DQ8 and I-Ag7 using a mechanism termed the P9 switch. Here, we built register-specific insulin peptide MHC tetramers to examine CD4+ T cell responses to Ins12–20 and Ins13–21 peptides during the early prediabetic phase of disease in nonobese diabetic (NOD) mice. A single-cell analysis of anti-insulin CD4+ T cells performed in 6- and 12-week-old NOD mice revealed tissue-specific gene expression signatures. TCR signaling and clonal expansion were found only in the islets of Langerhans and produced either classical TH1 differentiation or an unusual Treg phenotype, independent of TCR usage. The early phase of the anti-insulin response was dominated by T cells specific for Ins12–20, the register that supports a P9 switch mode of recognition. The presence of the P9 switch was demonstrated by TCR sequencing, reexpression, mutagenesis, and functional testing of TCRαβ pairs in vitro. Genetic correction of the I-Aβ57 mutation in NOD mice resulted in the disappearance of D/E residues in the CDR3β of anti-Ins12–20 T cells. These results provide a mechanistic molecular explanation that links the characteristic MHC class II polymorphism of T1D with the recognition of islet autoantigens and disease onset.

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The Interaction Between DOT1L and AF10 Is Required for H3K79 Dimethylation and MLL-AF9 Leukemia

Blood ◽

10.1182/blood.v120.21.401.401 ◽

2012 ◽

Vol 120 (21) ◽

pp. 401-401

Author(s):

Aniruddha J Deshpande ◽

Liying Chen ◽

Kathrin M Bernt ◽

Stuart Dias ◽

Deepti Banka ◽

...

Keyword(s):

Gene Expression ◽

Mass Spectrometry ◽

Target Gene ◽

Leucine Zipper ◽

Target Genes ◽

Fusion Gene ◽

Transformed Cells ◽

Target Gene Expression ◽

Transforming Activity ◽

H3k79 Methylation

Abstract Abstract 401 MLL-fusion proteins induce changes in histone modifications that result in the abnormal and sustained expression of downstream oncogenic target genes. A number of recent studies have identified aberrant histone 3 lysine 79 (H3K79) methylation by the chromatin modifying enzyme DOT1L as an important epigenetic modification that sustains MLL-target gene expression. Aberrant H3K79 methylation has been shown to be necessary for oncogenic transformation mediated by a number of MLL-fusions. These recent findings have generated tremendous interest in H3K79 methylation as a therapeutic target in the MLL rearranged leukemias. The plant-homeodomain (PHD) and leucine zipper-containing protein AF10 biochemically interacts with DOT1L and is believed to influence H3K79 methylation. We generated conditional knockout mice in which the Dot1l-interacting octapeptide-motif leucine zipper (OM-LZ) domain of Af10 was flanked by LoxP sites. Deletion of the Af10OM-LZ domain with the Cre recombinase is predicted to abrogate the Af10-Dot1l interaction. Deletion of the Af10OM-LZ domain greatly reduced global H3K79 dimethylation as assessed by immunoblotting as well as mass spectrometry in Af10OM-LZ deleted HoxA9/Meis1a transformed cells. Given the importance of H3K79 methylation in MLL-rearranged leukemias, we sought to assess whether the transforming activity of the MLL-AF9 fusion gene was dependent on the Af10-Dot1l interaction. Using an MLL-AF9-IRES-GFP encoding retrovirus, we established immortalized blast-colony forming cultures from mouse lineage negative Sca-1 positive/Kit positive (LSK) bone marrow cells bearing floxed Af10OM-LZ alleles. Deletion of the Af10OM-LZ domain with Cre-recombinase dramatically reduced H3K79me2 on the MLL-target genes Hoxa5-10 and Meis1, leading to downregulation of these transcripts. We performed colony-forming cell (CFC) assays from MLL-AF9 transformed cells in the presence or absence of the Af10OM-LZ allele. In the first week, Af10OM-LZ deletion profoundly impaired the blast-colony forming potential of MLL-AF9 transformed LSKs and the only clones that could serially replate in subsequent passages had escaped Af10OM-LZ excision. Af10OM-LZ deleted colonies were very small and spread-out and showed morphological features of terminal myeloid differentiation. In contrast, HoxA9/Meis1 transformed LSK cells expanded normally in the absence of the Af10OM-LZ domain. These results demonstrate that the Af10OM-LZ, much like Dot1l, is critical for the in vitro transforming activity of the MLL-AF9 fusion gene, but does not non-specifically inhibit cellular proliferation. We then sought to investigate the potential role of the Af10OM-LZ domain in the in vivo leukemogenic activity of MLL-AF9. We generated primary MLL-AF9 leukemias from LSKs harboring floxed Af10OM-LZ alleles. Deletion of the Af10OM-LZ domain in cells explanted from the MLL-AF9 primary leukemias led to a significant increase in the disease latency in secondary recipient mice. Moreover, limiting dilution analysis of MLL-AF9 leukemias with or without the Af10OM-LZ domain demonstrated a >100 fold decrease in the frequency of leukemia initiating cells in the absence of the Af10OM-LZ domain. Microarray analysis showed that a vast majority of MLL-AF9 target genes were significantly downregulated in Af10OM-LZ deleted as compared to Af10OM-LZ wildtype MLL-AF9 leukemias. However, the Af10OM-LZ deleted cells could still eventually cause leukemia. This is intriguing given that Af10OM-LZ deletion, similar to Dot1l deletion, leads to a significant reduction in H3K79 dimethylation as well as MLL-target gene expression. A more detailed analysis of H3K79 methylation using mass spectrometry revealed that in contrast to H3K79 dimethylation, global levels of H3K79 mono-methylation were largely unchanged in Af10OM-LZ deleted cells. This suggests the residual MLL-AF9 target gene expression seen in Af10OM-LZ deleted cells is maintained by H3K79 monomethylation. Our results demonstrate a surprising role for Af10 in the conversion of H3K79 monomethylation to dimethylation and reveal the AF10-DOT1L interaction as an attractive therapeutic target in MLL-rearranged leukemias. Disclosures: Armstrong: Epizyme: Consultancy.

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E2f1, E2f2, and E2f3 Control E2F Target Expression and Cellular Proliferation via a p53-Dependent Negative Feedback Loop

Molecular and Cellular Biology ◽

10.1128/mcb.02147-05 ◽

2007 ◽

Vol 27 (1) ◽

pp. 65-78 ◽

Cited By ~ 59

Author(s):

Cynthia Timmers ◽

Nidhi Sharma ◽

Rene Opavsky ◽

Baidehi Maiti ◽

Lizhao Wu ◽

...

Keyword(s):

Gene Expression ◽

Target Gene ◽

Target Genes ◽

Cellular Proliferation ◽

Kinase Activity ◽

Cyclin Dependent Kinase ◽

Control Of Gene Expression ◽

Target Gene Expression ◽

Rb Phosphorylation ◽

P53 Target Genes

ABSTRACT E2F-mediated control of gene expression is believed to have an essential role in the control of cellular proliferation. Using a conditional gene-targeting approach, we show that the targeted disruption of the entire E2F activator subclass composed of E2f1, E2f2, and E2f3 in mouse embryonic fibroblasts leads to the activation of p53 and the induction of p53 target genes, including p21 CIP1 . Consequently, cyclin-dependent kinase activity and retinoblastoma (Rb) phosphorylation are dramatically inhibited, leading to Rb/E2F-mediated repression of E2F target gene expression and a severe block in cellular proliferation. Inactivation of p53 in E2f1-, E2f2-, and E2f3-deficient cells, either by spontaneous mutation or by conditional gene ablation, prevented the induction of p21 CIP1 and many other p53 target genes. As a result, cyclin-dependent kinase activity, Rb phosphorylation, and E2F target gene expression were restored to nearly normal levels, rendering cells responsive to normal growth signals. These findings suggest that a critical function of the E2F1, E2F2, and E2F3 activators is in the control of a p53-dependent axis that indirectly regulates E2F-mediated transcriptional repression and cellular proliferation.

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