scholarly journals Regulation of differential proton-coupled folate transporter gene expression in human tumors: transactivation by KLF15 with NRF-1 and the role of Sp1

2019 ◽  
Vol 476 (8) ◽  
pp. 1247-1266
Author(s):  
Zhanjun Hou ◽  
Carrie O'Connor ◽  
Josephine Frühauf ◽  
Steve Orr ◽  
Seongho Kim ◽  
...  
Keyword(s):  
Reporter Gene ◽  
Transcriptional Control ◽  
Consensus Sequence ◽  
Minimal Promoter ◽  
Mobility Shift ◽  
Nuclear Extracts ◽  
Ht1080 Cells ◽  
Promoter Construct ◽  
Mobility Shift Assay ◽  
Reporter Gene Assays

Abstract Tumors can be therapeutically targeted with novel antifolates (e.g. AGF94) that are selectively transported by the human proton-coupled folate transporter (hPCFT). Studies were performed to determine the transcription regulation of hPCFT in tumors and identify possible mechanisms that contribute to the highly disparate levels of hPCFT in HepG2 versus HT1080 tumor cells. Transfection of hPCFT-null HT1080 cells with hPCFT restored transport and sensitivity to AGF94. Progressive deletions of the hPCFT promoter construct (−2005 to +96) and reporter gene assays in HepG2 and HT1080 cells confirmed differences in hPCFT transactivation and localized a minimal promoter to between positions −50 and +96. The minimal promoter included KLF15, GC-Box and NRF-1 cis-binding elements whose functional importance was confirmed by promoter deletions and mutations of core consensus sequences and reporter gene assays. In HepG2 cells, NRF-1, KLF15 and Sp1 transcripts were increased over HT1080 cells by ∼5.1-, ∼44-, and ∼2.4-fold, respectively. In Drosophila SL2 cells, transfection with KLF15 and NRF-1 synergistically activated the hPCFT promoter; Sp1 was modestly activating or inhibitory. Chromatin immunoprecipitation and electrophoretic mobility shift assay (EMSA) and supershifts confirmed differential binding of KLF15, Sp1, and NRF-1 to the hPCFT promoter in HepG2 and HT1080 cells that paralleled hPCFT levels. Treatment of HT1080 nuclear extracts (NE) with protein kinase A increased Sp1 binding to its consensus sequence by EMSA, suggesting a role for Sp1 phosphorylation in regulating hPCFT transcription. A better understanding of determinants of hPCFT transcriptional control may identify new therapeutic strategies for cancer by modulating hPCFT levels in combination with hPCFT-targeted antifolates.

Olf-1-binding site: characterization of an olfactory neuron-specific promoter motif

1993 ◽  
Vol 13 (5) ◽  
pp. 3002-3014
Author(s):  
K Kudrycki ◽  
C Stein-Izsak ◽  
C Behn ◽  
M Grillo ◽  
R Akeson ◽  
...  
Keyword(s):  
Nuclear Protein ◽  
Consensus Sequence ◽  
Binding Motif ◽  
Sequence Motif ◽  
Olfactory Neuron ◽  
Sequence Motifs ◽  
Mobility Shift ◽  
Specific Expression ◽  
Mobility Shift Assay

We report characterization of several domains within the 5' flanking region of the olfactory marker protein (OMP) gene that may participate in regulating transcription of this and other olfactory neuron-specific genes. Analysis by electrophoretic mobility shift assay and DNase I footprinting identifies two regions that contain a novel sequence motif. Interactions between this motif and nuclear proteins were detected only with nuclear protein extracts derived from olfactory neuroepithelium, and this activity is more abundant in olfactory epithelium enriched in immature neurons. We have designated a factor(s) involved in this binding as Olf-1. The Olf-1-binding motif consensus sequence was defined as TCCCC(A/T)NGGAG. Studies with transgenic mice indicate that a 0.3-kb fragment of the OMP gene containing one Olf-1 motif is sufficient for olfactory tissue-specific expression of the reporter gene. Some of the other identified sequence motifs also interact specifically with olfactory nuclear protein extracts. We propose that Olf-1 is a novel, olfactory neuron-specific trans-acting factor involved in the cell-specific expression of OMP.

scholarly journals Analysis of nuclear glucocorticoid receptor-DNA interaction in aged rat liver

2005 ◽  
Vol 70 (5) ◽  
pp. 705-712 ◽  
Author(s):  
Miroslava Vujcic ◽  
Natasa Terzic ◽  
Aleksandra Ristic-Fira ◽  
Dusan Kanazir ◽  
Sabera Ruzdijic
Keyword(s):  
Dna Interaction ◽  
Binding Activity ◽  
Regulatory Proteins ◽  
Nuclear Proteins ◽  
Middle Aged ◽  
Mobility Shift ◽  
Nuclear Extracts ◽  
Supershift Assay ◽  
Mobility Shift Assay ◽  
Oligonucleotide Analogues

Abstract: In order to contribute to the understanding of mechanisms by which regulatory proteins recognize genetic information stored in DNA, analyses of their interaction with specific nucleotides are usually performed. In this study, the electrophoretic mobility shift assay (EMSA) was applied to analyze the interaction of nuclear proteins from the liver of rats of different age i.e., young (3-month-old), middle- aged (12-month-old) and aged (24-month-old), with radioactively labelled synthetic oligonucleotide analogues, corresponding to GRE. The levels of GRE binding activity were assessed by quantitative densitometric scanning of the autoradiograms. The results showed statistically significant decreasing values of up to 78% and 49% in middle aged and old animals, respectively, compared to young animals (p < 0.05). The specificity of the nuclear proteins-GRE interaction was demonstrated by competition experiments with unlabelled GRE. In a supershift assay, using the antibody BuGR2, it was shown that the GR proteins present in nuclear extracts have a high affinity for the GRE probe. The stabilities of the protein-DNA complexes were analysed and it was concluded that they changed during ageing. .

scholarly journals A Sequence of the CIS Gene Promoter Interacts Preferentially with Two Associated STAT5A Dimers: a Distinct Biochemical Difference between STAT5A and STAT5B

1998 ◽  
Vol 18 (10) ◽  
pp. 5852-5860 ◽  
Author(s):  
Frédérique Verdier ◽  
Raquel Rabionet ◽  
Fabrice Gouilleux ◽  
Christian Beisenherz-Huss ◽  
Paule Varlet ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Target Genes ◽  
Prolactin Receptor ◽  
Gene Promoter ◽  
Expression Vectors ◽  
Mobility Shift ◽  
Nuclear Extracts ◽  
Mobility Shift Assay ◽  
Binding Sequence ◽  
Biochemical Difference

ABSTRACT Two distinct genes encode the closely related signal transducer and activator of transcription proteins STAT5A and STAT5B. The molecular mechanisms of gene regulation by STAT5 and, particularly, the requirement for both STAT5 isoforms are still undetermined. Only a few STAT5 target genes, among them the CIS (cytokine-inducible SH2-containing protein) gene, have been identified. We cloned the human CIS gene and studied the human CIS gene promoter. This promoter contains four STAT binding elements organized in two pairs. By electrophoretic mobility shift assay studies using nuclear extracts of UT7 cells stimulated with erythropoietin, we showed that these four sequences bound to STAT5-containing complexes that exhibited different patterns and affinities: the three upstream STAT binding sequences bound to two distinct STAT5-containing complexes (C0 and C1) and the downstream STAT box bound only to the slower-migrating C1 band. Using nuclear extracts from COS-7 cells transfected with expression vectors for the prolactin receptor, STAT5A, and/or STAT5B, we showed that the C1 complex was composed of a STAT5 tetramer and was dependent on the presence of STAT5A. STAT5B lacked this property and bound with a stronger affinity than did STAT5A to the four STAT sequences as a homodimer (C0 complex). This distinct biochemical difference between STAT5A and STAT5B was confirmed with purified activated STAT5 recombinant proteins. Moreover, we showed that the presence on the same side of the DNA helix of a second STAT sequence increased STAT5 binding and that only half of the palindromic STAT binding sequence was sufficient for the formation of a STAT5 tetramer. Again, STAT5A was essential for this cooperative tetrameric association. This property distinguishes STAT5A from STAT5B and could be essential to explain the transcriptional regulation diversity of STAT5.

scholarly journals A novel cis-acting element controlling the rat CYP2D5 gene and requiring cooperativity between C/EBP beta and an Sp1 factor.

1994 ◽  
Vol 14 (2) ◽  
pp. 1383-1394 ◽  
Author(s):  
Y H Lee ◽  
M Yano ◽  
S Y Liu ◽  
E Matsunaga ◽  
P F Johnson ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Ternary Complex ◽  
Sequence Similarity ◽  
Consensus Sequence ◽  
Regulatory Region ◽  
Mrna Levels ◽  
Binding Studies ◽  
Mobility Shift ◽  
Specific Expression ◽  
Nuclear Extracts

The rat CYP2D5 gene encodes a cytochrome P450 and is expressed in liver cells. Its expression commences a few days after birth, and maximal mRNA levels are achieved when animals reach puberty. Transfection and DNA binding studies were performed to investigate the mechanism controlling developmentally programmed, liver-specific expression of CYP2D5. Transfection studies using a series of CYP2D5 upstream DNA chloramphenicol acetyltransferase gene fusion constructs identified a segment of DNA between nucleotides -55 and -156 that conferred transcriptional activity in HepG2 cells. Activity was markedly increased by cotransfection with a vector expressing C/EBP beta but was unaffected by vectors producing other liver-enriched transcription factors (C/EBP alpha, HNF-1 alpha, and DBP). DNase I footprinting revealed a region protected by both HepG2 and liver cell nuclear extracts between nucleotides -83 and -112. This region displayed some sequence similarity to the Sp1 consensus sequence and was able to bind the Sp1 protein, as assessed by a gel mobility shift assay. The role of Sp1 in CYP2D5 transcription was confirmed by trans activation of the 2D5-CAT construct in Drosophila melanogaster cells by using an Sp1 expression vector. C/EBP beta alone was unable to directly bind the -83 to -112 region of the promoter but was able to produce a ternary complex when combined with HepG2 nuclear extracts or recombinant human Sp1. C/EBP alpha was unable to substitute for C/EBP beta in forming this ternary complex. A poor C/EBP binding site is present adjacent to the Sp1 site, and mutagenesis of this site abolished formation of the ternary complex with the CYP2D5 regulatory region. These result establish that two transcription factors can work in conjunction, possibly by protein-protein interaction, to activate the CYP2D5 gene.

scholarly journals The NF-κB p50 Subunit Is Protective during Intestinal Entamoeba histolytica Infection of 129 and C57BL/6 Mice

2010 ◽  
Vol 78 (4) ◽  
pp. 1475-1481 ◽  
Author(s):  
Kyou-Nam Cho ◽  
Stephen M. Becker ◽  
Eric R. Houpt
Keyword(s):  
Entamoeba Histolytica ◽  
Electrical Resistance ◽  
Transepithelial Electrical Resistance ◽  
Enzyme Linked Immunosorbent Assay ◽  
Mobility Shift ◽  
Protective Function ◽  
Targeted Deletion ◽  
Nuclear Extracts ◽  
Histolytica Infection ◽  
Mobility Shift Assay

ABSTRACT Entamoeba histolytica is the agent of amebic colitis. In this work we examined the intestinal NF-κB response to this parasite. Using an enzyme-linked immunosorbent assay (ELISA) and an electrophoretic mobility shift assay, we found that the NF-κB subunit p50 predominated in nuclear extracts of whole cecal tissue and of isolated crypts from mice inoculated with E. histolytica. p50 was protective, since C57BL/6 and 129 mice in which there was targeted deletion of this subunit were more susceptible to E. histolytica infection as measured by culture results, cecal parasite ELISA results, and/or histologic scores. The transepithelial electrical resistance of cecal explants from C57BL/6 and 129 p50 knockout mice decreased markedly in response to the parasite compared with the transepithelial electrical resistance of their wild-type counterparts, suggesting that a protective function of p50 was present in the epithelium itself. This work shows that NF-κB activity, particularly activity of the p50 subunit, is one factor that contributes to resistance of the gut to E. histolytica infection.

scholarly journals Olf-1-binding site: characterization of an olfactory neuron-specific promoter motif.

1993 ◽  
Vol 13 (5) ◽  
pp. 3002-3014 ◽  
Author(s):  
K Kudrycki ◽  
C Stein-Izsak ◽  
C Behn ◽  
M Grillo ◽  
R Akeson ◽  
...  
Keyword(s):  
Nuclear Protein ◽  
Consensus Sequence ◽  
Binding Motif ◽  
Sequence Motif ◽  
Olfactory Neuron ◽  
Sequence Motifs ◽  
Mobility Shift ◽  
Specific Expression ◽  
Mobility Shift Assay

We report characterization of several domains within the 5' flanking region of the olfactory marker protein (OMP) gene that may participate in regulating transcription of this and other olfactory neuron-specific genes. Analysis by electrophoretic mobility shift assay and DNase I footprinting identifies two regions that contain a novel sequence motif. Interactions between this motif and nuclear proteins were detected only with nuclear protein extracts derived from olfactory neuroepithelium, and this activity is more abundant in olfactory epithelium enriched in immature neurons. We have designated a factor(s) involved in this binding as Olf-1. The Olf-1-binding motif consensus sequence was defined as TCCCC(A/T)NGGAG. Studies with transgenic mice indicate that a 0.3-kb fragment of the OMP gene containing one Olf-1 motif is sufficient for olfactory tissue-specific expression of the reporter gene. Some of the other identified sequence motifs also interact specifically with olfactory nuclear protein extracts. We propose that Olf-1 is a novel, olfactory neuron-specific trans-acting factor involved in the cell-specific expression of OMP.

scholarly journals Transcriptional and Functional Analysis of the Neisseria gonorrhoeae Fur Regulon

2009 ◽  
Vol 192 (1) ◽  
pp. 77-85 ◽  
Author(s):  
Lydgia A. Jackson ◽  
Thomas F. Ducey ◽  
Michael W. Day ◽  
Jeremy B. Zaitshik ◽  
Joshua Orvis ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Transcriptional Control ◽  
Cell Communication ◽  
Essential Element ◽  
Open Reading Frames ◽  
Promoter Regions ◽  
Mobility Shift ◽  
Sequence Logos ◽  
Mobility Shift Assay

ABSTRACT To ensure survival in the host, bacteria have evolved strategies to acquire the essential element iron. In Neisseria gonorrhoeae, the ferric uptake regulator Fur regulates metabolism through transcriptional control of iron-responsive genes by binding conserved Fur box (FB) sequences in promoters during iron-replete growth. Our previous studies showed that Fur also controls the transcription of secondary regulators that may, in turn, control pathways important to pathogenesis, indicating an indirect role for Fur in controlling these downstream genes. To better define the iron-regulated cascade of transcriptional control, we combined three global strategies—temporal transcriptome analysis, genomewide in silico FB prediction, and Fur titration assays (FURTA)—to detect genomic regions able to bind Fur in vivo. The majority of the 300 iron-repressed genes were predicted to be of unknown function, followed by genes involved in iron metabolism, cell communication, and intermediary metabolism. The 107 iron-induced genes encoded hypothetical proteins or energy metabolism functions. We found 28 predicted FBs in FURTA-positive clones in the promoters and within the open reading frames of iron-repressed genes. We found lower levels of conservation at critical thymidine residues involved in Fur binding in the FB sequence logos of FURTA-positive clones with intragenic FBs than in the sequence logos generated from FURTA-positive promoter regions. In electrophoretic mobility shift assay studies, intragenic FBs bound Fur with a lower affinity than intergenic FBs. Our findings further indicate that transcription under iron stress is indirectly controlled by Fur through 12 potential secondary regulators.

scholarly journals Molecular regulation of the human IL-3 gene: inducible T cell-restricted expression requires intact AP-1 and Elf-1 nuclear protein binding sites.

1993 ◽  
Vol 178 (5) ◽  
pp. 1681-1692 ◽  
Author(s):  
L R Gottschalk ◽  
D M Giannola ◽  
S G Emerson
Keyword(s):  
T Cells ◽  
Transcription Factors ◽  
T Cell ◽  
Protein Binding ◽  
Binding Site ◽  
Binding Sites ◽  
Nuclear Protein ◽  
Mobility Shift ◽  
Nuclear Extracts ◽  
Mobility Shift Assay

Interleukin 3 (IL-3) is a hematopoietic stem-cell growth and differentiation factor that is expressed solely in activated T and NK cells. Studies to date have identified elements 5' to the IL-3 coding sequences that regulate its transcription, but the sequences that confer T cell-specific expression remain to be clearly defined. We have now identified DNA sequences that are required for T cell-restricted IL-3 gene transcription. A series of transient transfections performed with human IL-3-chloramphenicol acetyltransferase (CAT) reporter plasmids in T and non-T cells revealed that a plasmid containing 319 bp of 5' flanking sequences was active exclusively in T cells. Deletion analysis revealed that T cell specificity was conferred by a 49-bp fragment (bp -319 to -270) that included a potential binding site for AP-1 transcription factors 6 bp upstream of a binding site for Elf-1, a member of the Ets family of transcription factors. DNaseI footprint and electrophoretic mobility shift assay analyses performed with MLA-144 T cell nuclear extracts demonstrated that this 49-bp region contains a nuclear protein binding region that includes consensus AP-1 and Elf-1 binding sites. In addition, extracts prepared from purified human T cells contained proteins that bound to synthetic oligonucleotides corresponding to the AP-1 and Elf-1 binding sites. In vitro-transcribed and -translated Elf-1 protein bound specifically to the Elf-1 site, and Elf-1 antisera competed and super shifted nuclear protein complexes present in MLA-144 nuclear extracts. Moreover, addition of anti-Jun family antiserum in electrophoretic mobility shift assay reactions completely blocked formation of the AP-1-related complexes. Transient transfection studies in MLA-144 T cells revealed that constructs containing mutations in the AP-1 site almost completely abolished CAT activity while mutation of the Elf-1 site or the NF-IL-3 site, a previously described nuclear protein binding site (bp. -155 to -148) in the IL-3 promoter, reduced CAT activity to &lt; 25% of the activity given by wild-type constructs. We conclude that expression of the human IL-3 gene requires the AP-1 and Elf-1 binding sites; however, unlike other previously characterized cytokine genes such as IL-2, the AP-1 and Elf-1 factors can bind independently in the IL-3 gene.(ABSTRACT TRUNCATED AT 400 WORDS)

A requirement for thioredoxin in redox-sensitive modulation of T-cadherin expression in endothelial cells

2008 ◽  
Vol 416 (2) ◽  
pp. 271-280 ◽  
Author(s):  
Manjunath B. Joshi ◽  
Danila Ivanov ◽  
Maria Philippova ◽  
Emmanouil Kyriakakis ◽  
Paul Erne ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endothelial Cells ◽  
Nuclear Extract ◽  
Mobility Shift ◽  
Protein Levels ◽  
Nuclear Extracts ◽  
Nucleoprotein Complex ◽  
Thioredoxin 1 ◽  
Mobility Shift Assay ◽  
Reporter Gene Analysis

T-cad (T-cadherin), a glycosylphosphatidylinositol-anchored cadherin superfamily member, is expressed widely in the brain and cardiovascular system, and absent, decreased, or even increased, in cancers. Mechanisms controlling T-cad expression are poorly understood. The present study investigated transcriptional regulation of T-cad in ECs (endothelial cells). Conditions of oxidative stress (serum-deprivation or presence of H2O2) elevate T-cad mRNA and protein levels in ECs. Reporter gene analysis, using serially deleted T-cad promoter stretches ranging from −99 to −2304 bp, located the minimal promoter region of T-cad within −285 bp from the translation start site. Reporter activity in ECs transfected with the −285 bp construct increased under conditions of oxidative stress, and this was normalized by antioxidant N-acetylcysteine. An electrophoretic-mobility-shift assay revealed a specific nucleoprotein complex unique to −156 to −203 bp, which increased when nuclear extracts from oxidatively stressed ECs were used, suggesting the presence of redox-sensitive binding element(s). MS analysis of the nucleoprotein complex unique to −156 to −203 bp after streptavidin–agarose pull-down detected the presence of the redox-active protein thioredoxin. The presence of thioredoxin-1 in a nuclear extract from oxidatively stressed ECs was demonstrated after immunoprecipitation and immunoblotting. Transfection of ECs with thioredoxin-1 small interfering RNA abrogated oxidative-stress-induced up-regulation of T-cad transcripts and protein. We conclude that thioredoxin-1 is an important determinant of redox-sensitive transcriptional up-regulation of T-cad in ECs.

scholarly journals Role of the IE62 Consensus Binding Site in Transactivation by the Varicella-Zoster Virus IE62 Protein

2010 ◽  
Vol 84 (8) ◽  
pp. 3767-3779 ◽  
Author(s):  
Kris White ◽  
Hua Peng ◽  
John Hay ◽  
William T. Ruyechan
Keyword(s):  
Dna Binding ◽  
Varicella Zoster Virus ◽  
Binding Site ◽  
Consensus Sequence ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Consensus Binding Site ◽  
Mobility Shift ◽  
Varicella Zoster ◽  
Mobility Shift Assay

ABSTRACT The varicella-zoster virus (VZV) IE62 protein is the major transcriptional activator. IE62 is capable of associating with DNA both nonspecifically and in a sequence-specific manner via a consensus binding site (5′-ATCGT-3′). However, the function of the consensus site is poorly understood, since IE62 efficiently transactivates promoter elements lacking this sequence. In the work presented here, sequence analysis of the VZV genome revealed the presence of 245 IE62 consensus sites throughout the genome. Some 54 sites were found to be present within putative VZV promoters. Electrophoretic mobility shift assay (EMSA) experiments using an IE62 fragment containing the IE62 DNA-binding domain and duplex oligonucleotides that did or did not contain the IE62 consensus binding sequence yielded KD (equilibrium dissociation constant) values in the nanomolar range. Further, the IE62 DNA binding domain was shown to have a 5-fold-increased affinity for its consensus site compared to nonconsensus sequences. The effect of consensus site presence and position on IE62-mediated activation of native VZV and model promoters was examined using site-specific mutagenesis and transfection and superinfection reporter assays. In all promoters examined, the consensus sequence functioned as a distance-dependent repressive element. Protein recruitment assays utilizing the VZV gI promoter indicated that the presence of the consensus site increased the recruitment of IE62 but not Sp1. These data suggest a model where the IE62 consensus site functions to down-modulate IE62 activation, and interaction of IE62 with this sequence may result in loss or decrease of the ability of IE62 to recruit cellular factors needed for full promoter activation.

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