scholarly journals Mechanism of Regulatory Target Selection by the SOX High-Mobility-Group Domain Proteins as Revealed by Comparison of SOX1/2/3 and SOX9

1999 ◽  
Vol 19 (1) ◽  
pp. 107-120 ◽  
Author(s):  
Yusuke Kamachi ◽  
Kathryn S. E. Cheah ◽  
Hisato Kondoh
Keyword(s):  
Binding Site ◽  
Target Genes ◽  
Target Selection ◽  
High Mobility ◽  
High Mobility Group ◽  
Dependent Manner ◽  
Activation Domains ◽  
Terminal Domain ◽  
Vp16 Fusion ◽  
Sox Proteins

ABSTRACT SOX proteins bind similar DNA motifs through their high-mobility-group (HMG) domains, but their action is highly specific with respect to target genes and cell type. We investigated the mechanism of target selection by comparing SOX1/2/3, which activate δ-crystallin minimal enhancer DC5, with SOX9, which activates Col2a1 minimal enhancer COL2C2. These enhancers depend on both the SOX binding site and the binding site of a putative partner factor. The DC5 site was equally bound and bent by the HMG domains of SOX1/2 and SOX9. The activation domains of these SOX proteins mapped at the distal portions of the C-terminal domains were not cell specific and were independent of the partner factor. Chimeric proteins produced between SOX1 and SOX9 showed that to activate the DC5 enhancer, the C-terminal domain must be that of SOX1, although the HMG domains were replaceable. The SOX2-VP16 fusion protein, in which the activation domain of SOX2 was replaced by that of VP16, activated the DC5 enhancer still in a partner factor-dependent manner. The results argue that the proximal portion of the C-terminal domain of SOX1/2 specifically interacts with the partner factor, and this interaction determines the specificity of the SOX1/2 action. Essentially the same results were obtained in the converse experiments in which COL2C2 activation by SOX9 was analyzed, except that specificity of SOX9-partner factor interaction also involved the SOX9 HMG domain. The highly selective SOX-partner factor interactions presumably stabilize the DNA binding of the SOX proteins and provide the mechanism for regulatory target selection.

scholarly journals SirR, a Novel Iron-Dependent Repressor inStaphylococcus epidermidis

1998 ◽  
Vol 66 (9) ◽  
pp. 4123-4129 ◽  
Author(s):  
Philip J. Hill ◽  
Alan Cockayne ◽  
Patrick Landers ◽  
Julie A. Morrissey ◽  
Catriona M. Sims ◽  
...  
Keyword(s):  
Binding Site ◽  
Dna Sequences ◽  
Blot Analysis ◽  
Target Genes ◽  
Consensus Sequence ◽  
Dependent Manner ◽  
Chromosomal Dna ◽  
Iron Starvation ◽  
Mobility Shift ◽  
Western Blots

ABSTRACT In Staphylococcus epidermidis and Staphylococcus aureus, a number of cell wall- and cytoplasmic membrane-associated lipoproteins are induced in response to iron starvation. To gain insights into the molecular basis of iron-dependent gene regulation in the staphylococci, we sequenced the DNA upstream of the 3-kb S. epidermidis sitABC operon, which Northern blot analysis indicates is transcriptionally regulated by the growth medium iron content. We identified two DNA sequences which are homologous to elements of the Corynebacterium diphtheriae DtxR regulon, which controls, in response to iron stress, for example, production of diphtheria toxin, siderophore, and a heme oxygenase. Upstream of thesitABC operon and divergently transcribed lies a 645-bp open reading frame (ORF), which codes for a polypeptide of approximately 25 kDa with homology to the DtxR family of metal-dependent repressor proteins. This ORF has been designated SirR (staphylococcal iron regulator repressor). Within thesitABC promoter/operator region, we also located a region of dyad symmetry overlapping the transcriptional start ofsitABC which shows high homology to the DtxR operator consensus sequence, suggesting that this region, termed the Sir box, is the SirR-binding site. The SirR protein was overexpressed, purified, and used in DNA mobility shift assays; SirR retarded the migration of a synthetic oligonucleotide based on the Sir box in a metal (Fe2+ or Mn2+)-dependent manner, providing confirmatory evidence that this motif is the SirR-binding site. Furthermore, Southern blot analysis of staphylococcal chromosomal DNA with the synthetic Sir box as a probe confirmed that there are at least five Sir boxes in the S. epidermidis genome and at least three in the genome of S. aureus, suggesting that SirR controls the expression of multiple target genes. Using a monospecific polyclonal antibody raised against SirR to probe Western blots of whole-cell lysates of S. aureus, S. carnosus,S. epidermidis, S. hominis, S. cohnii, S. lugdunensis, and S. haemolyticus, we identified an approximately 25-kDa cross-reactive protein in each of the staphylococcal species examined. Taken together, these data suggest that SirR functions as a divalent metal cation-dependent transcriptional repressor which is widespread among the staphylococci.

scholarly journals High Mobility Group Box 1: a Novel Host Restriction Factor in Zika Virus Replication

2021 ◽  
Author(s):  
Kim-Ling Chin ◽  
Nurhafiza binti Zainal ◽  
Sing-Sin Sam ◽  
Pouya Hassandarvish ◽  
Rafidah Lani ◽  
...  
Keyword(s):  
Zika Virus ◽  
Severe Disease ◽  
High Mobility ◽  
High Mobility Group ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Zikv Infection ◽  
Hmgb1 Level ◽  
Antiviral Effects ◽  
Huh7 Cells

Abstract Neonatal microcephaly and adult Guillain-Barré syndrome are severe complications of Zika virus (ZIKV) infection. The robustly induced inflammatory cytokine expressions in ZIKV-infected patients may constitute a hallmark for severe disease. In the present study, the potential role of high mobility group box 1 protein (HMGB1) in ZIKV infection was investigated. HMGB1 protein expression was determined by the enzyme-linked immunosorbent assay (ELISA) and immunoblot assay. HMGB1’s role in ZIKV infection was also explored using treatment with dexamethasone, an immunomodulatory drug. Antiviral effects of dexamethasone treatment on both wild-typed (WT) and HMGB1-knockdown (shHMGB1) Huh7 cells were determined by the focus-forming assay. Results showed that the Huh7 cells were highly susceptible to ZIKV infection. The infection was found to induce HMGB1 nuclear-to-cytoplasmic translocation, resulting in a >99% increase in the cytosolic HMGB1 expression at 72h.p.i. The extracellular HMGB1 level was elevated in a time- and multiplicity of infection (MOI)- dependent manner. Dexamethasone 150 µM treatment of the ZIKV-infected cells reduced HMGB1 extracellular release in a dose-dependent manner, with a maximum reduction of 71 ± 5.84% (p < 0.01). The treatment also reduced virus titers by over 83 ± 0.50% (p < 0.01). The antiviral effects, however, was not observed in the dexamethasone-treated HMGB1-knockdown cells, suggesting the importance of the intracellular HMGB1 in ZIKV infection. Overall, these results suggest that translocation of HMGB1 occurred during ZIKV infection and inhibition of the translocation reduced ZIKV replication. These findings highlight the potential of developing therapeutics against ZIKV infection by affecting the translocation of HMGB1 from the nucleus to the cytoplasm.

scholarly journals New Insights into the Pleiotropic Drug Resistance Network from Genome-Wide Characterization of the YRR1 Transcription Factor Regulation System

2002 ◽  
Vol 22 (8) ◽  
pp. 2642-2649 ◽  
Author(s):  
Stéphane Le Crom ◽  
Frédéric Devaux ◽  
Philippe Marc ◽  
Xiaoting Zhang ◽  
W. Scott Moye-Rowley ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Transcription Factor ◽  
Binding Site ◽  
Time Course ◽  
Target Genes ◽  
Regulation System ◽  
Dependent Manner ◽  
Pleiotropic Drug Resistance ◽  
Genome Wide

ABSTRACT Yrr1p is a recently described Zn2Cys6 transcription factor involved in the pleiotropic drug resistance (PDR) phenomenon. It is controlled in a Pdr1p-dependent manner and is autoregulated. We describe here a new genome-wide approach to characterization of the set of genes directly regulated by Yrr1p. We found that the time-course production of an artificial chimera protein containing the DNA-binding domain of Yrr1p activated the 15 genes that are also up-regulated by a gain-of-function mutant of Yrr1p. Gel mobility shift assays showed that the promoters of the genes AZR1, FLR1, SNG1, YLL056C, YLR346C, and YPL088W interacted with Yrr1p. The putative consensus Yrr1p binding site deduced from these experiments, (T/A)CCG(C/T)(G/T)(G/T)(A/T)(A/T), is strikingly similar to the PDR element binding site sequence recognized by Pdr1p and Pdr3p. The minor differences between these sequences are consistent with Yrr1p and Pdr1p and Pdr3p having different sets of target genes. According to these data, some target genes are directly regulated by Pdr1p and Pdr3p or by Yrr1p, whereas some genes are indirectly regulated by the activation of Yrr1p. Some genes, such as YOR1, SNQ2, and FLR1, are clearly directly controlled by both classes of transcription factor, suggesting an important role for the corresponding membrane proteins.

scholarly journals Salvianolic acid B protects against myocardial ischaemia-reperfusion injury in rats via inhibiting high mobility group box 1 protein expression through the PI3K/Akt signalling pathway

2019 ◽  
Vol 393 (8) ◽  
pp. 1527-1539 ◽  
Author(s):  
Hanqing Liu ◽  
Wei Liu ◽  
Huiliang Qiu ◽  
Dezhi Zou ◽  
Huayang Cai ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Myocardial Ischaemia ◽  
Myocardial Injury ◽  
High Mobility ◽  
Salvianolic Acid B ◽  
High Mobility Group ◽  
High Dose ◽  
Dependent Manner ◽  
Salvianolic Acid ◽  
Ischaemia Reperfusion

AbstractSalvianolic acid B (Sal B) has a significant protective effect on myocardial ischaemia-reperfusion (I/R) injury. Therefore, the aims of this study were to determine the effects of Sal B on myocardial ischaemic-reperfusion (I/R) injury in rats and to explore whether its underlying mechanism of cardioprotection occurs through activating the expression of the phosphoinositide 3-kinase/protein, kinase B (PI3K/Akt) and inhibiting the expression of high mobility group protein 1 (HMGB1). Ninety Sprague-Dawley rats were randomized into five groups: group 1 (sham-operated), group 2 (myocardial I/R), group 3 (low dose of Sal B+I/R), group 4 (high dose of Sal B+I/R), and group 5 (high dose of Sal B+I/R+LY294002, which is a specific PI3k inhibitor). All I/R rats received 30 min myocardial ischaemia followed by 24-h reperfusion. Cardiac function, infarct size, myocardial injury marker levels, inflammatory response and cardiomyocyte apoptosis as well as Bcl-2, Bax, P-Akt, HMGB1 and TLR4 expression were measured. In the current study, Sal B significantly ameliorated myocardial I/R injury in a dose-dependent manner, ameliorated cardiac function, reduced myocardial infarction size, decreased myocardial injury marker expression, decreased inflammatory responses, reduced apoptosis, activated PI3K/Akt expression and inhibited HMGB1 expression. However, all effects of Sal B were significantly reversed by LY294002. Overall, the present study indicated that Sal B attenuated myocardial I/R injury by activating PI3K/Akt and inhibiting the release of HMGB1 in rats.

scholarly journals High-mobility group box-1 as an autocrine trophic factor in white matter stroke

2017 ◽  
Vol 114 (25) ◽  
pp. E4987-E4995 ◽  
Author(s):  
Jun Young Choi ◽  
Yuexian Cui ◽  
Samma Tasneem Chowdhury ◽  
Byung Gon Kim
Keyword(s):  
White Matter ◽  
Signaling Pathways ◽  
High Mobility ◽  
Glucose Deprivation ◽  
High Mobility Group ◽  
Dependent Manner ◽  
Protective Effects ◽  
Tlr2 Ligand ◽  
Health And Disease ◽  
Trophic Signaling

Maintenance of white matter integrity in health and disease is critical for a variety of neural functions. Ischemic stroke in the white matter frequently results in degeneration of oligodendrocytes (OLs) and myelin. Previously, we found that toll-like receptor 2 (TLR2) expressed in OLs provides cell-autonomous protective effects on ischemic OL death and demyelination in white matter stroke. Here, we identified high-mobility group box-1 (HMGB1) as an endogenous TLR2 ligand that promotes survival of OLs under ischemic stress. HMGB1 rapidly accumulated in the culture medium of OLs exposed to oxygen–glucose deprivation (OGD). This conditioned medium exhibited a protective activity against ischemic OL death that was completely abolished by immunodepletion of HMGB1. Knockdown of HMGB1 or application of glycyrrhizin, a specific HMGB1 inhibitor, aggravated OGD-induced OL death, and recombinant HMGB1 application reduced the extent of OL death in a TLR2-dependent manner. We confirmed that cytosolic translocation of HMGB1 and activation of TLR2-mediated signaling pathways occurred in a focal white matter stroke model induced by endothelin-1 injection. Animals with glycyrrhizin coinjection showed an expansion of the demyelinating lesion in a TLR2-dependent manner, accompanied by aggravation of sensorimotor behavioral deficits. These results indicate that HMGB1/TLR2 activates an autocrine trophic signaling pathways in OLs and myelin to maintain structural and functional integrity of the white matter under ischemic conditions.

scholarly journals High-mobility group box 1 protein induces tissue factor expression in vascular endothelial cells via activation of NF-κB and Egr-1

2009 ◽  
Vol 102 (08) ◽  
pp. 352-359 ◽  
Author(s):  
Haichao Wang ◽  
Yiting Tang ◽  
Zhang Fan ◽  
Ben Lv ◽  
Xianzhong Xiao ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Surface ◽  
Tissue Factor ◽  
Vascular Endothelial Cells ◽  
High Mobility ◽  
High Mobility Group ◽  
Cell Surface Receptors ◽  
Dependent Manner ◽  
Vascular Endothelial ◽  
Surface Receptors

SummaryHigh-mobility group box 1 protein (HMGB1), an abundant nuclear protein, was recently established as a proinflammatory mediator of experimental sepsis.Although extracellular HMGB1 has been found in atherosclerotic plaques, its potential role in the pathogenesis of atherothrombosis remains elusive. In the present study, we determined whether HMGB1 induces tissue factor (TF) expression in vascular endothelial cells (ECs) and macrophages. Our data showed that HMGB1 stimulated ECs to express TF (but not TF pathway inhibitor) mRNA and protein in a concentration and time-dependent manner. Blockade of cell surface receptors (including TLR4, TLR2, and RAGE) with specific neutralising antibodies partially reduced HMGB1-induced TF expression. Moreover, HMGB1 increased expression of Egr-1 and nuclear translocation of NF-κB (c-Rel/p65) in ECs. Taken together, our data suggest that HMGB1 induces TF expression in vascular endothelial cells via cell surface receptors (TLR4, TLR2, and RAGE), and through activation of transcription factors (NF-κB and Egr-1).

scholarly journals The Myc Transactivation Domain Promotes Global Phosphorylation of the RNA Polymerase II Carboxy-Terminal Domain Independently of Direct DNA Binding

2007 ◽  
Vol 27 (6) ◽  
pp. 2059-2073 ◽  
Author(s):  
Victoria H. Cowling ◽  
Michael D. Cole
Keyword(s):  
Dna Binding ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcription Initiation ◽  
Target Genes ◽  
Dependent Manner ◽  
Transactivation Domain ◽  
Pol Ii ◽  
Terminal Domain ◽  
Ctd Phosphorylation

ABSTRACT Myc is a transcription factor which is dependent on its DNA binding domain for transcriptional regulation of target genes. Here, we report the surprising finding that Myc mutants devoid of direct DNA binding activity and Myc target gene regulation can rescue a substantial fraction of the growth defect in myc −/− fibroblasts. Expression of the Myc transactivation domain alone induces a transcription-independent elevation of the RNA polymerase II (Pol II) C-terminal domain (CTD) kinases cyclin-dependent kinase 7 (CDK7) and CDK9 and a global increase in CTD phosphorylation. The Myc transactivation domain binds to the transcription initiation sites of these promoters and stimulates TFIIH binding in an MBII-dependent manner. Expression of the Myc transactivation domain increases CDK mRNA cap methylation, polysome loading, and the rate of translation. We find that some traditional Myc transcriptional target genes are also regulated by this Myc-driven translation mechanism. We propose that Myc transactivation domain-driven RNA Pol II CTD phosphorylation has broad effects on both transcription and mRNA metabolism.

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