scholarly journals Sp1-Mediated Transcription of the Werner Helicase Gene Is Modulated by Rb and p53

1998 ◽  
Vol 18 (11) ◽  
pp. 6191-6200 ◽  
Author(s):  
Yukako Yamabe ◽  
Akira Shimamoto ◽  
Makoto Goto ◽  
Jun Yokota ◽  
Minoru Sugawara ◽  
...  

ABSTRACT The regulation of Werner’s syndrome gene (WRN) expression was studied by characterizing the cis-regulatory elements in the promoter region and the trans-activating factors that bind to them. First, we defined the transcription initiation sites and the sequence of the 5′ upstream region (2.8 kb) ofWRN that contains a number of cis-regulatory elements, including 7 Sp1, 9 retinoblastoma control element (RCE), and 14 AP2 motifs. A region consisting of nucleotides −67 to +160 was identified as the principal promoter of WRN by reporter gene assays in HeLa cells, using a series of WRNpromoter-luciferase reporter (WRN-Luc) plasmids that contained the 5′-truncated or mutated WRN upstream regions. In particular, two Sp1 elements proximal to the transcription initiation site are indispensable for WRN promoter activity and bind specifically to Sp1 proteins. The RCE enhances WRN promoter activity. Coexpression of the WRN-Luc plasmids with various dosages of plasmids expressing Rb or p53 in Saos2 cells lacking active Rb and p53 proteins showed that the introduced Rb upregulates WRN promoter activity a maximum of 2.5-fold, while p53 downregulates it a maximum of 7-fold, both dose dependently. Consistently, the overexpressed Rb and p53 proteins also affected the endogenous WRN mRNA levels in Saos2 cells, resulting in an increase with Rb and a decrease with p53. These findings suggest that WRN expression, like that of other housekeeping genes, is directed mainly by the Sp1 transcriptional control system but is also further modulated by transcription factors, including Rb and p53, that are implicated in the cell cycle, cell senescence, and genomic instability.

2000 ◽  
Vol 347 (2) ◽  
pp. 485-490
Author(s):  
Clara AMEIXA ◽  
Paul M. BRICKELL

Development of the cellular complexity of the vertebrate neural retina relies on an intricate interplay between extracellular signals and intracellular factors. In particular, transcription factors play a key role in determining the competence of cells to respond to extracellular signals. We have previously shown that, in the developing chick neural retina, expression of the retinoid X receptor-γ (RXR-γ2) nuclear receptor gene is restricted to photoreceptors. To characterize the mechanisms that regulate expression of this gene in the neural retina, we isolated a chicken RXR-γ genomic clone containing the RXR-γ2 promoter and mapped the transcription initiation site by means of ribonuclease protection. We analysed promoter activity by transient transfection of luciferase reporter gene constructs into cultured cells isolated from embryonic-chick neural retina or facial mesenchyme, which does not normally express detectable RXR-γ2 transcripts. The DNA fragment lying between nucleotides -657 and +37 with respect to the transcription initiation site had basal promoter activity in both cell types. The fragment lying between nucleotides -1198 and -991 directed 10-20-fold higher levels of luciferase activity in neural retina cells, but only basal levels in facial mesenchyme cells. This 208 bp fragment also enhanced the activity of the simian-virus-40 promoter, when placed upstream in either orientation. Electrophoretic-mobility-shift assays using this 208 bp fragment demonstrated the formation of four neural retina-specific protein-DNA complexes. These results indicate that regulation of RXR-γ2 transcription in the developing chick neural retina involves the binding of one or more neural retina-specific protein factors to an enhancer element located approx. 1 kbp upstream of the transcription initiation site.


2010 ◽  
Vol 84 (21) ◽  
pp. 11470-11478 ◽  
Author(s):  
Baoling Ying ◽  
Ann E. Tollefson ◽  
William S. M. Wold

ABSTRACT We previously identified an adenovirus (Ad) protein named U exon protein (UXP) encoded by a leftward-strand (l-strand) transcription unit. Here we identify and characterize the UXP promoter. Primer extension and RNase protection assays mapped the transcription initiation site at 32 nucleotides upstream of the UXP gene initiation codon. A series of viral mutants with mutations at two putative inverted CCAAT (I-CCAAT) boxes and two E2F sites were generated. With mutants lacking the proximal I-CCAAT box, the UXP mRNA level decreased significantly to 30% of the Ad type 5 (Ad5) mRNA level as measured by quantitative reverse transcription-PCR. Decreased UXP was also observed by immunoblotting and immunofluorescence. UXP mRNA and protein levels were similar to those of Ad5 for mutants lacking the distal I-CCAAT box or both putative E2F sites. Ad DNA levels were similar in mutant- and wild-type Ad5-infected cells during the late stage of infection, strongly suggesting that the decreased UXP mRNA and protein from mutants lacking the proximal I-CCAAT box was due to decreased promoter activity. Electrophoretic mobility shift assays (EMSA) indicated that a cellular factor binds specifically to the proximal I-CCAAT box of the UXP promoter. An in vitro luciferase reporter assay demonstrated that basal promoter activity lies between bp −158 and +30 of the transcription initiation site. No E1A-mediated promoter transactivation was observed in 293 cells compared with A549 cells. Thus, we propose that there is a previously unidentified Ad5 promoter that drives expression of the UXP transcription unit. This promoter is embedded within the gene for fiber, and it contains a proximal I-CCAAT box critical for UXP mRNA transcription.


2005 ◽  
Vol 393 (1) ◽  
pp. 321-329 ◽  
Author(s):  
Antonella De Luca ◽  
Paolo Sacchetta ◽  
Carmine Di Ilio ◽  
Bartolo Favaloro

MsrA (methionine sulphoxide reductase A) is an antioxidant repair enzyme that reduces oxidized methionine to methionine. Moreover, the oxidation of methionine residues in proteins is considered to be an important consequence of oxidative damage to cells. To understand mechanisms of human msrA gene expression and regulation, we cloned and characterized the 5′ promoter region of the human msrA gene. Using 5′-RACE (rapid amplification of cDNA ends) analysis of purified mRNA from human cells, we located the transcription initiation site 59 nt upstream of the reference MsrA mRNA sequence, GenBank® accession number BC 054033. The 1.3 kb of sequence located upstream of the first exon of msrA gene was placed upstream of the luciferase reporter gene in a pGL3-Basic vector and transfected into different cell lines. Sequentially smaller fragments of the msrA promoter region were generated by PCR, and expression levels were monitored from these constructs within HEK-293 and MCF7 human cell lines. Analysis of deletion constructs revealed differences in promoter activity in these cell lines. In HEK-293 cells, the promoter activity was constant from the minimal promoter region to the longest fragment obtained. On the other hand, in MCF7 cells we detected a down-regulation in the longest fragment. Mutation of a putative negative regulatory region that is located between −209 and −212 bp (the CCAA box) restored promoter activity in MCF7 cells. The location of the msrA promoter will facilitate analysis of the transcriptional regulation of this gene in a variety of pathological contexts.


2007 ◽  
Vol 407 (1) ◽  
pp. 101-111 ◽  
Author(s):  
Ian Pearse ◽  
Ying X. Zhu ◽  
Eleanor J. Murray ◽  
Pradeep K. Dudeja ◽  
Krishnamurthy Ramaswamy ◽  
...  

We have previously cloned the human Na+/H+ exchanger NHE2 gene and its promoter region. In the present study, the regulatory elements responsible for the constitutive expression of NHE2 were studied. Transient transfection assays revealed that the −40/+150 promoter region contains the core promoter responsible for the optimal promoter activity. A smaller fragment, −10/+40, containing the TIS (transcription initiation site) showed minimal activity. We identified a palindrome that overlaps the TIS and binds to the transcription factors Sp1 and Sp3. Mutations in the 5′ flank of the palindrome abolished the Sp1/Sp3 interaction and reduced promoter activity by approx. 45%. In addition, a conserved GC-box centered at −25 was found to play a critical role in basal promoter activity and also interacted with Sp1 and Sp3. An internal deletion in the GC-box severely reduced the promoter activity. Sp1/Sp3 binding to these elements was established using gel-mobility shift assays, confirmed by chromatin immunoprecipitation and co-transfections in Drosophila SL2 cells. Furthermore, we identified two positive regulatory elements in the DNA region corresponding to the 5′-UTR (5′-untranslated region). The results in the present study indicate that Sp1 and Sp3 are required for constitutive NHE2 expression and that the positive regulatory elements of the 5′-UTR may co-operate with the 5′-flanking region to achieve the optimal promoter activity.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1603-1603 ◽  
Author(s):  
Xingwu Zheng ◽  
Masami Niiya ◽  
X. Long Zheng ◽  
Eleanor S. Pollak

Abstract ADAMTS13 (A Disintegrin And Metalloprotease with ThromboSpondin type 1 repeats-13) controls von Willebrand factor multimer sizes by cleaving the Tyr1605-Met1606 bond in the central A2 domain. Deficiency of plasma ADAMTS13 activity can result in a lethal syndrome, thrombotic thrombocytopenic purpura (TTP). ADAMTS13 is primarily synthesized in hepatic stellate cells (HSCs), endothelial cells and megakaryocytes. We determined the transcription initiation site, the core region for promoter activity, the putative transcription factor binding sites as well as the influence of inflammatory cytokines on ADAMTS13 promoter activity. To explore the transcriptional control of ADAMTS13 gene expression, we constructed reporter genes containing 991 base pairs (bp) of the ADAMTS13 5′ untranslated (UT) region. We showed by deletion mutagenesis and luciferase reporter expression that the proximal-most 197 bp region was required for maximal luciferase activity in transfected cells in the human hepatic stellate cell line (LX-2) and in the human hepatocyte-like cell line (HepG2); the major transcription initiation site determined by 5′ - RACE was found at 77 bp upstream from the translation start site (ATG). However, the minimal sequences that were required for the promoter activity varied depending on the cells, with required sequences of approximately 147 and 127 bp in LX-2 and HepG2 cells, respectively. The proximal ADAMTS13 promoter region is evolutionally conserved between humans, mice and rats. This region is rich in GC content (72%) and contains putative binding sites for the transcription factors heat shock factor-2 (HSF2), FOXa2 [also named hepatocyte nuclear factor 3beta (HNF-3b)] and AP-1. A footprint assay demonstrated that the region between −116 and −126, containing the putative FOXa2 binding site, was largely protected by Dnase I digestion. The luciferase reporter activity was suppressed in cells transfected with the plasmid containing the proximal 314 bp human 5′ UT ADAMTS13 sequence in parallel with the inflammatory cytokines found to be elevated in patients with TTP: IL-4, TNF-alpha and INF-gamma. These inflammatory cytokines inhibited the Adamts13 mRNA and protein expression in rat primary HSCs in culture in a dose dependent manner. Approximately 70%, 71% and 80% of Adamts13 mRNA (by real time RT-PCR) and 77%, 78% and 92% of Adamts13 proteolytic activity (by FRETS-VWF73) were suppressed at 48 hours by IL-4 (10 ng/ml), TNF-alpha (10 ng/ml) and INF-gamma (100 ng/ml), respectively. We conclude that under physiological conditions ADAMTS13 synthesis may be strictly maintained at relatively low levels by binding transcription factors, whereas under pathological conditions inflammatory cytokines, released due to systemic inflammation, may further suppress ADAMTS13 gene expression, which may result in thrombotic complications. However, the mechanism regarding how the inflammatory cytokines negatively regulate ADAMTS13 (or Adamts13) synthesis remains to be determined.


Genes ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 977 ◽  
Author(s):  
Lanyue Hu ◽  
Quanmei Chen ◽  
Yitao Wang ◽  
Na Zhang ◽  
Peixin Meng ◽  
...  

Prenyl diphosphate synthase subunit 2 (PDSS2) is the first key enzyme in the CoQ10 biosynthesis pathway, and contributes to various metabolic and nephritic diseases. It has been reported that PDSS2 is downregulated in several types of tumors and acts as a potential tumor suppressor gene to inhibit the proliferation and migration of cancer cells. However, the regulatory mechanism of PDSS2 expression remains elusive. In the present study, we first identified and characterized the PDSS2 promoter region. We established four different luciferase reporter constructs which mainly cover the 2 kb region upstream of the PDSS2 gene transcription initiation site. Series luciferase reporter assay demonstrated that all four constructs have prominent promoter activity, and the core promoter of PDSS2 is mainly located within the 202 bp region near its transcription initiation site. Transcription factor binding site analysis revealed that the PDSS2 promoter contains binding sites for canonical transcription factors such as Sp1 and GATA-1. Overexpression of Sp1 significantly inhibited PDSS2 promoter activity, as well as its endogenous expression, at both mRNA and protein levels in lung cancer cells. Site-directed mutagenesis assay further confirmed that the Sp1 binding sites are essential for proximal prompter activity of PDSS2. Consistently, a selective Sp1 inhibitor, mithramycin A, treatment repressed the PDSS2 promoter activity, as well as its endogenous expression. Chromatin immunoprecipitation (ChIP) assay revealed that Sp1 binds to the PDSS2 promoter in vivo. Of note, the expression of Sp1 and PDSS2 are negatively correlated, and higher Sp1 expression with low PDSS2 expression is significantly associated with poor prognosis in lung cancer. Taken together, our results strongly suggest the essential role of Sp1 in maintaining the basic constitutive expression of PDSS2, and the pathogenic implication of Sp1-mediated PDSS2 transcriptional repression in lung cancer cells.


1993 ◽  
Vol 296 (3) ◽  
pp. 663-670 ◽  
Author(s):  
M F Wilkemeyer ◽  
E R Andrews ◽  
F D Ledley

Methylmalonyl-CoA mutase (MCM) is a nuclear-encoded mitochondrial matrix enzyme. We have reported characterization of murine MCM and cloning of a murine MCM cDNA and now describe the murine Mut locus, its promoter and evidence for tissue-specific variation in MCM mRNA, enzyme and holo-enzyme levels. The Mut locus spans 30 kb and contains 13 exons constituting a unique transcription unit. A B1 repeat element was found in the 3′ untranslated region (exon 13). The transcription initiation site was identified and upstream sequences were shown to direct expression of a reporter gene in cultured cells. The promoter contains sequence motifs characteristic of: (1) TATA-less housekeeping promoters; (2) enhancer elements purportedly involved in co-ordinating expression of nuclear-encoded mitochondrial proteins; and (3) regulatory elements including CCAAT boxes, cyclic AMP-response elements and potential AP-2-binding sites. Northern blots demonstrate a greater than 10-fold variation in steady-state mRNA levels, which correlate with tissue levels of enzyme activity. However, the ratio of holoenzyme to total enzyme varies among different tissues, and there is no correlation between steady-state mRNA levels and holoenzyme activity. These results suggest that, although there may be regulation of MCM activity at the level of mRNA, the significance of genetic regulation is unclear owning to the presence of epigenetic regulation of holoenzyme formation.


1988 ◽  
Vol 8 (7) ◽  
pp. 2896-2909 ◽  
Author(s):  
E A Sternberg ◽  
G Spizz ◽  
W M Perry ◽  
D Vizard ◽  
T Weil ◽  
...  

Terminal differentiation of skeletal myoblasts is accompanied by induction of a series of tissue-specific gene products, which includes the muscle isoenzyme of creatine kinase (MCK). To begin to define the sequences and signals involved in MCK regulation in developing muscle cells, the mouse MCK gene has been isolated. Sequence analysis of 4,147 bases of DNA surrounding the transcription initiation site revealed several interesting structural features, some of which are common to other muscle-specific genes and to cellular and viral enhancers. To test for sequences required for regulated expression, a region upstream of the MCK gene from -4800 to +1 base pairs, relative to the transcription initiation site, was linked to the coding sequences of the bacterial chloramphenicol acetyltransferase (CAT) gene. Introduction of this MCK-CAT fusion gene into C2 muscle cells resulted in high-level expression of CAT activity in differentiated myotubes and no detectable expression in proliferating undifferentiated myoblasts or in nonmyogenic cell lines. Deletion mutagenesis of sequences between -4800 and the transcription start site showed that the region between -1351 and -1050 was sufficient to confer cell type-specific and developmentally regulated expression on the MCK promoter. This upstream regulatory element functioned independently of position, orientation, or distance from the promoter and therefore exhibited the properties of a classical enhancer. This upstream enhancer also was able to confer muscle-specific regulation on the simian virus 40 promoter, although it exhibited a 3- to 5-fold preference for its own promoter. In contrast to the cell type- and differentiation-specific expression of the upstream enhancer, the MCK promoter was able to function in myoblasts and myotubes and in nonmyogenic cell lines when combined with the simian virus 40 enhancer. An additional positive regulatory element was identified within the first intron of the MCK gene. Like the upstream enhancer, this intragenic element functioned independently of position, orientation, and distance with respect to the MCK promoter and was active in differentiated myotubes but not in myoblasts. These results demonstrate that expression of the MCK gene in developing muscle cells is controlled by complex interactions among multiple upstream and intragenic regulatory elements that are functional only in the appropriate cellular context.


Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 3067-3077 ◽  
Author(s):  
J.S. Margolis ◽  
M.L. Borowsky ◽  
E. Steingrimsson ◽  
C.W. Shim ◽  
J.A. Lengyel ◽  
...  

The gap gene hunchback (hb) is required for the formation and segmentation of two regions of the Drosophila embryo, a broad anterior domain and a narrow posterior domain. Accumulation of hb transcript in the posterior of the embryo occurs in two phases, an initial cap covering the terminal 15% of the embryo followed by a stripe at the anterior edge of this region. By in situ hybridization with transcript-specific probes, we show that the cap is composed only of mRNA from the distal transcription initiation site (P1), while the later posterior stripe is composed of mRNA from both the distal and proximal (P2) transcription initiation sites. Using a series of genomic rescue constructs and promoter-lacZ fusion genes, we define a 1.4 kb fragment of the hb upstream region that is both necessary and sufficient for posterior expression. Sequences within this fragment mediate regulation by the terminal gap genes tailless (tll) and a huckebein, which direct the formation of the posterior hb stripe. We show that the tll protein binds in vitro to specific sites within the 1.4 kb posterior enhancer region, providing the first direct evidence for activation of gene expression by tll. We propose a model in which the anterior border of the posterior hb stripe is determined by tll concentration in a manner analogous to the activation of anterior hb expression by bicoid.


1999 ◽  
Vol 276 (3) ◽  
pp. H826-H833 ◽  
Author(s):  
Karen A. Detillieux ◽  
Johanna T. A. Meij ◽  
Elissavet Kardami ◽  
Peter A. Cattini

Fibroblast growth factor (FGF-2), a mitogenic, angiogenic, and cardioprotective agent, is reported to be released from the postnatal heart by a mechanism of transient remodeling of the sarcolemma during contraction. This release can be increased with adrenergic stimulation. RNA blotting was used to assess whether FGF-2 synthesis in neonatal rat cardiomyocytes might also be regulated by adrenergic stimulation. FGF-2 RNA levels were increased after treatment with norepinephrine for 6 h or with the α-adrenergic agonist phenylephrine for 48 h. To assess an effect on transcription, neonatal rat cardiomyocytes were transfected with a hybrid rat FGF-2 promoter/luciferase gene (−1058FGFp. luc) and treated with norepinephrine or phenylephrine for 6 or 48 h, respectively. FGF-2 promoter activity was increased two- to sevenfold in an α1-specific manner. Putative phenylephrine-responsive elements (PEREs) were identified at positions −780 and −761 relative to a major transcription initiation site. However, deletion analysis of −1058FGFp. luc showed that the phenylephrine response was independent of the putative PEREs, cell contraction, and Ca2+ influx. In transgenic mice expressing −1058FGFp. luc, a significant three- to sevenfold stimulation of FGF-2 promoter activity was detected in the hearts of two independent lines 6 h after intraperitoneal administration of phenylephrine (50 mg/kg). This increase was still apparent at 24 h but was not detected at 48 h posttreatment. Analysis of FGF-2 mRNA in normal mouse hearts revealed accumulation of the 6.1-kb transcript at 24 h. Control of local FGF-2 synthesis at the transcriptional level through adrenergic stimulation may be important in the response to injury as well as in the maintenance of a healthy myocardium.


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