Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:2.7.7.48 (transcriptase)
9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human intercellular adhesion molecule-1 (ICAM-1), a specific ligand for the lymphocyte function-associated Ag-1 (LFA-1), plays an important role in leukocyte-endothelial cell interactions. It is induced by proinflammatory cytokines such as IL-1, TNF-alpha, or IFN-gamma. However, little is known concerning the intracellular regulatory mechanisms which trigger ICAM-1 up-regulation. In order to study potential regulatory elements involved in ICAM-1 induction we have cloned the human ICAM-1 gene and 5 kb of its 5'-regulatory region. The sequence of the cDNA was found to be distributed over seven exons separated by six introns, whereby each of the five extracellular Ig-like domains of ICAM-1 is encoded by its own exon. The upstream sequence harbors a number of sequence motifs implicated in the regulation and expression of eukaryotic genes, including binding sites for the transcription factors SP-1, AP-1, and NF-kB. Primer extension and S1 nuclease analysis revealed two transcription initiation sites 319 bp and 41 bp upstream of the translation start site. Consensus TATA boxes were found at the expected positions about 25 bp upstream of both start sites. Reverse transcriptase polymerase chain reaction showed differential use of the two TATA boxes in A549 and HS913T cells. Both RNA seem to code for the same for of ICAM-1 protein. For regulation studies a 1.3-kb EcoRI/SalI fragment of the 5'-flanking region was used to promote transcription of a linked luciferase reporter gene in transient-transfection assays in A549 and HS913T cells. Treatment of A549 cells with IL-1 or TNF-alpha resulted in a two- or fourfold increase in luciferase activity. Furthermore, a sixfold induction could be achieved after treatment with the phorbol ester PMA. In contrast, agents that increase intracellular cAMP levels did not induce luciferase activity. Northern blot analysis was used to investigate the kinetics of ICAM-1 mRNA synthesis upon induction with TNF-alpha and PMA. These data suggest that the up-regulation of ICAM-1 by cytokines occurs at least partly at the transcriptional level. Deletion analysis of the 1.3-kb fragment of the 5'-flanking region revealed sequences responsible for promotion and inhibition of transcription. In particular, two functionally distinct regions have been characterized: a short fragment containing an NF-kB binding site has been shown to function as an activator, followed immediately downstream by a sequence acting as a silencer element. Therefore, ICAM-1 gene expression seems to be modulated by multiple cis-acting elements.
...
PMID:Cloning of the human gene for intercellular adhesion molecule 1 and analysis of its 5'-regulatory region. Induction by cytokines and phorbol ester. 168 Sep 19

Giardia lamblia, a prevalent human pathogen and one of the lineages that branched earliest from prokaryotes, can be infected with a double-stranded RNA virus, giardiavirus (GLV). The 6,277-bp viral genome has been previously cloned (A.L. Wang, H.-M. Yang, K.A. Shen, and C.C. Wang, Proc. Natl. Acad. Sci. USA 90:8595-8599, 1993; C.-H. Wu, C.C. Wang, H.M. Yang, and A.L. Wang, Gene, in press) and was converted to a transfection vector for G. lamblia in the present study. By flanking the firefly luciferase gene with the 5' and 3' untranslated regions (UTRs) of the GLV genome, transcript of the construct was synthesized in vitro with T7 polymerase and used to transfect G. lamblia WB trophozoites already infected with GLV (WBI). Optimal electroporation conditions used for the transfection were set at 1,000 V/cm and 500 microF, which resulted in expression of significant luciferase activity up to 120 h after electroporation. Furthermore, the mRNA and the antisense RNA of the luciferase gene were both detected by reverse transcription and PCR from 6 to 120 h postelectroporation, whereas no antisense RNA of luciferase was observed in the electroporated virus-free Giardia WB trophozoites. The mRNA of luciferase was detectable in the virus-free trophozoites by reverse transcription and PCR only up to 20 h after the electroporation, indicating that the introduced mRNA was replicated only by the viral RNA-dependent RNA polymerase inside the WBI cells. This expression of luciferase was dependent on the presence of UTRs on both ends of the viral genome transcript, including a putative packaging site that was apparently indispensable for luciferase expression. This is the first time that a viral vector in the form of mRNA URTs has been successfully used in transfecting a protozoan.
...
PMID:Virus-mediated expression of firefly luciferase in the parasitic protozoan Giardia lamblia. 765 5

EBNA 1 is the only antigen expressed in both Epstein-Barr virus (EBV)-infected nasopharyngeal carcinoma (NPC) and Burkitt's lymphoma cells. Previous studies showed that the mRNA of EBNA 1 in these two tumor tissues was initiated from a promoter located in the Bam HI F fragment (Fp) on the viral genome. Two regulatory elements located in the downstream Bam HI Q region include an EBNA 1 binding site and a positive regulatory region between the Fp and the EBNA1 binding site. This data strongly suggested that a cellular factor(s) may modulate the usage of the Fp. To locate the shortest responsible viral sequence, we constructed a series of luciferase gene and chloramphenicol acetyltransferase (CAT) gene plasmids that contained various portions of the Bam HI F/Q region. Plasmid DNA was then introduced into cells to examine the promoter activity of each construct. By this method, we identified a 186-bp fragment within the Bam HI Q region that possessed the highest activity. This promoter was designated as Qp and found to be orientation-dependent and down-regulated by EBNA 1 in both the type I BL cells and human epithelial cells. Furthermore, RNase protection assay showed that a transcription initiation site was located at nucleotide 62,416 of the EBV genome. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis further confirmed that the transcript was initiated from the Qp, and not the Fp. Therefore, our data suggested that a novel promoter, Qp, located within the Bam HI Q existed for the EBNA 1 expression in the latently infected type 1 BL cells. The biological significance of the selection of the Qp needs further investigation.
...
PMID:Identification of a novel promoter located within the Bam HI Q region of the Epstein-Barr virus genome for the EBNA 1 gene. 766 54

Higher-order RNA structures in the 3' untranslated region (3'UTR) of enteroviruses are thought to play a pivotal role in viral negative-strand RNA synthesis. The structure of the 3'UTR was predicted by thermodynamic calculations using the STAR (structural analysis of RNA) computer program and experimentally verified using chemical and enzymatic probing of in vitro-synthesized RNA. A possible pseudoknot interaction between the 3D polymerase coding sequence and domain Y and a "kissing" interaction between domains X and Y was further studied by mutational analysis, using an infectious coxsackie B3 virus cDNA clone (domain designation as proposed by E. V. Pilipenko, S. V. Maslova, A. N. Sinyakov, and V.I. Agol (Nucleic Acids Res. 20:1739-1745, 1992). The higher-order RNA structure of the 3'UTR appeared to be maintained by an intramolecular kissing interaction between the loops of the two predominant hairpin structures (X and Y) within the 3'UTR. Disturbing this interaction had no effect on viral translation and processing of the polyprotein but exerted a primary effect on viral replication, as was demonstrated in a subgenomic coxsackie B3 viral replicon, in which the capsid P1 region was replaced by the luciferase gene. Mutational analysis did not support the existence of the pseudoknot interaction between hairpin loop Y and the 3D polymerase coding sequence. Based on these experiments, we constructed a three-dimensional model of the 3'UTR of coxsackie B virus that shows the kissing interaction as the essential structural feature of the origin of replication required for its functional competence.
...
PMID:Kissing of the two predominant hairpin loops in the coxsackie B virus 3' untranslated region is the essential structural feature of the origin of replication required for negative-strand RNA synthesis. 898

An oxidant stress has been shown to prevail in experimental and clinical nephrotic syndrome. Such oxidant stress may be induced by a reduced activity of antioxidant systems. We examined the altered expression of manganese-superoxide dismutase (Mn-SOD), an antioxidant enzyme, in patients with idiopathic nephrotic syndrome, in whom an increased oxidant stress had been demonstrated. The Mn-SOD activities in peripheral blood mononuclear cells obtained from 12 patients with active nephrotic syndrome (6.0 +/- 1.1 years of age, mean +/- SE) and hypoproteinemia were 42% lower (p < 0.05) than in 12 control subjects (5.5 +/- 0.5 years of age) with normal serum total protein concentrations. Reverse-transcriptase polymerase chain reaction also demonstrated that Mn-SOD messenger RNA expression in the patients with nephrotic syndrome was, on average, 59% lower than in control subjects. Because expressions of some genes are sensitive to serum, the serum dependency of Mn-SOD gene transcription was studied in glomerular endothelial cells transfected with a luciferase reporter gene fused with a rat Mn-SOD DNA fragment of -806 to +22 bp of the transcription initiation site (-806:+22). When these cells were exposed to different concentrations of fetal bovine serum (0.5% to 15%), the transcriptional activities determined by luciferase activities were proportional to serum concentrations. This serum-dependent transcriptional activation was also demonstrated by the fragment (-220:+22) but not by the fragment (-220:-20). When glomerular endothelial cells transfected with the fragment (-220:+22) were treated with 5% serum from patients with active nephrotic syndrome, transcriptional activation was more than 80% less than that by 5% serum from control subjects without nephrosis. These results indicate that Mn-SOD gene transcription is regulated at least in part by serum, and that the serum-dependent transcription of the gene is diminished in patients with idiopathic nephrotic syndrome. The regulatory region of serum-dependent gene transcription resides within its early promoter region. Our findings suggest that down-regulation of antioxidant enzyme transcription may contribute increased oxidant stress in idiopathic nephrotic syndrome.
...
PMID:Down-regulation of manganese-superoxide dismutase gene expression in idiopathic nephrotic syndrome. 915 91

The growth-promoting activity of GH, the principal hormonal determinant of body size, is mediated by insulin-like growth factor I (IGF-I). Most of the IGF-I in plasma circulates in a 150-kDa complex that contains IGF-binding protein-3 (IGFBP-3) and an acid-labile subunit (ALS). The 150-kDa complex serves as a reservoir of IGF-I and determines its bioavailability to the tissues. Formation of the 150-kDa complex depends upon the synthesis of ALS, which is synthesized primarily in liver and is regulated by GH. The present study demonstrates that GH stimulates ALS gene transcription in rat liver and ALS promoter activity in a rat hepatoma cell line. ALS messenger RNA (mRNA) and ALS nuclear transcripts were decreased to similar extents in the livers of GH-deficient hypophysectomized rats. GH increased hepatic ALS mRNA within 3-4 h to about 65% of the levels seen in sham-operated control rats. To confirm that GH stimulated ALS gene transcription, we transiently transfected an ALS promoter-luciferase reporter gene construct into H4-II-E rat hepatoma cells and primary rat hepatocytes. Recombinant human GH (hGH) stimulated promoter activity about 3-fold. In contrast, basal promoter activity was lower, and GH stimulation was absent when the ALS reporter construct was transfected into GH-responsive 3T3-F442A mouse preadipocyte fibroblasts. GH stimulation of ALS promoter activity in H4-II-E cells was mediated by functional GH receptors; nonprimate (rat and bovine) GH gave identical stimulation to hGH, and stimulation by hGH occurred at physiological concentrations. Reverse transcriptase-PCR analysis indicated that GH receptor mRNA was present in H4-II-E cells at approximately 40% of the level seen in rat liver. GH also induced the expression of the endogenous c-fos gene, indicating that the signaling pathway necessary for the activation of gene expression by GH was intact in H4-II-E cells. Thus, H4-II-E cells are a GH-responsive liver cell line that should provide a useful system in which to study the molecular mechanism of transcriptional regulation by GH of ALS and other hepatic genes.
...
PMID:Growth hormone stimulates transcription of the gene encoding the acid-labile subunit (ALS) of the circulating insulin-like growth factor-binding protein complex and ALS promoter activity in rat liver. 917 59

GnRH receptors belong to the family of G protein-coupled receptor proteins and have been localized to the anterior pituitary, brain and reproductive organs as well as many steroid-dependent tumor tissues. Recently, cDNAs for the GnRH receptors of several species including the human have been cloned. To determine the structure of the gene encoding the human GnRH receptor, we isolated the receptor gene clones from the human genomic libraries. Comparison of the genomic and cDNA sequences revealed that the human GnRH receptor gene is composed of three exons and two introns and spans over 20 kb in size. Exon 1 encodes the 5' untranslated sequence and nucleotide +1 to +522 in the open reading frame, exon 2 encodes nucleotide +523 to +742 and exon 3 encodes nucleotide +743 to +987 in the open reading frame as well as the 3' untranslated sequence. Southern blot analysis of genomic DNA and localization of the GnRH receptor gene to a single site on human chromosome 4 (4q13) indicate the presence of a single copy of the gene in the human genome. Several regulatory sequences for various hormones and other regulatory factors were identified, including PEA-3, AP-1, AP-2, and Pit-1 sites. In addition, glucocorticoid/progesterone response element thyroid hormone response element, and cAMP response element sequences were identified. Reverse transcriptase-primer extension and 5' RACE analysis of the human pituitary RNA demonstrated the presence of multiple transcriptional start sites upstream of the translational start site. Analysis of the 5' flanking region of the gene also revealed the presence of multiple TATA and CAAT sequences. The finding of multiple transcriptional start sites raises the possibility of tissue-specific regulation and the existence of variable size transcripts. Chimeras containing 1.26 kb (-534 to 728) of the 5' flanking region of the receptor gene and the luciferase (Luc) gene expressed a significant luciferase activity when transfected into a human endometrial tumor cell line (HEC-1A) and a breast tumor cell line (MCF-7) but not in a mouse pituitary gonadotrope cell line (alpha T3-1), suggesting the existence of multiple promoter elements in the gene. These findings indicate a multiplicity of regulation of expression of the GnRH receptor and provide the substrate for detailed investigation in the reproductive system.
...
PMID:Molecular structure of the human gonadotropin-releasing hormone receptor gene. 1102 3

Elucidation of the regulation of human sodium-iodide symporter (hNIS) gene expression is critical to understanding its effects on iodide concentration abilities of thyroid and thyroid carcinomas. To explore this issue, a 1.2-kb portion of the 5'-flanking region of the hNIS gene was isolated and characterized. Transient transfections with chimeric luciferase-reporter constructs into a differentiated human thyroid cell line, KAT-50, as well as non-thyroidal cells, defined an active promoter with tissue-specificity. Reverse-transcriptase polymerase chain reaction analysis for hNIS mRNA expression in normal human tissues was positive in thyroid, salivary gland, omentum, and gallbladder. KAT-50 cells expressed hNIS mRNA and were capable of thyrotropin-responsive iodide uptake in vitro. Despite the failure to exhibit iodide concentration in clinical anaplastic carcinoma tumors, 4 of 5 cell lines from this cancer phenotype expressed hNIS mRNA. Definition of the active promoter provides further insights and tools to uncover new approaches to use of radioiodine for therapy of thyroid carcinomas.
...
PMID:Cloning of the human sodium-iodide symporter promoter and characterization in a differentiated human thyroid cell line, KAT-50. 949 56

The recent discovery of chemokine receptors as coreceptors for human immunodeficiency virus-type 1 (HIV-1) entry offers new avenues for investigating the pathogenesis of acquired immunodeficiency syndrome (AIDS)-related cytopenias. To this end, we sought to (1) phenotype human hematopoietic cells for CD4 and the HIV-1 coreceptors CXCR4, CCR5, CCR3, and CCR2b; (2) correlate CD4 and chemokine receptor expression with their susceptibility to HIV-1 infection; and (3) examine any potential interplay between inflammatory cytokines released during HIV-1 infection and regulation of chemokine receptor expression. Fluorescence-activated cell sorting (FACS) analysis of bone marrow mononuclear cells (BMMNC), cells derived from serum-free expanded hematopoietic lineages (colony-forming unit-granulocyte-macrophage [CFU-GM], colony-forming unit-megakaryocyte [CFU-Meg], and burst-forming unit-erythroid [BFU-E]), and CD34(+) cells showed differential expression of chemokine receptors and CD4 with some lineage specificity. Significantly, FACS-sorted CXCR4(+)/CD34(+) cells had the same clonogeneic potential as CXCR4(-)/CD34(+) cells. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of FACS-sorted human candidate stem cells (HSC; CD34(+), c-kit+, Rho123(low)) showed the presence of CXCR4 mRNA but not CD4 mRNA. Infection studies with HIV-1 Env-pseudotyped luciferase reporter viruses indicated that X4 Env (CXCR4-using) pseudotypes infected megakaryocytic cells, whereas R5 Env (CCR5-using) pseudotypes did not. Similarly, R5 but not X4 Env-pseudotyped viruses infected granulocyte-macrophage cells in a CD4/CCR5-dependent manner. Erythroid cells were resistant to R5 or X4 viral infection. Finally, we found that gamma-interferon treatment upregulated CXCR4 expression on primary hematopoietic cells. In summary, the delineation of chemokine receptor expression on primary hematopoietic cells is a first step towards dissecting the chemokine-chemokine receptor axes that may play a role in hematopoietic cell proliferation and homing. Furthermore, susceptibility of hematopoietic cells to HIV-1 infection is likely to be more complicated than the mere physical presence of CD4 and the cognate chemokine receptor. Lastly, our results suggest a potential interplay between gamma-interferon secretion and CXCR4 expression.
...
PMID:Coreceptor/chemokine receptor expression on human hematopoietic cells: biological implications for human immunodeficiency virus-type 1 infection. 994 56

To investigate mechanisms of human angiotensin II type 2 receptor (hAT2) gene regulation we functionally characterized the promoter and downstream regions of the gene. 5'-Terminal deletion mutants from -1417/+100 to -46/+100 elicited significant but low functional activity in luciferase reporter gene assays with PC12W cells. Inclusion into the promoter constructs of intron 1 and the transcribed region of the hAT2 gene up to the translation start enhanced luciferase activity 6.7+/-1.6-fold and 11.6+/-1.7-fold (means+/-S.E.M.) respectively, whereas fusion of the promoter to the spliced 5' untranslated region of hAT2 cDNA did not, which indicated an enhancement caused by intronic sequence elements. Reverse transcriptase-mediated PCR confirmed that the chimaeric hAT2-luciferase mRNA was regularly spliced in PC12W cells. A Northern blot analysis of transfected cells showed levels of luciferase mRNA expression consistent with the respective enzyme activities. Mapping of intron 1 revealed that a 12 bp sequence in the centre of the intron was required for the increase in promoter activity, whereas the 5' adjacent intronic region mediated a decrease in luciferase activity. Mutation of the 12 bp region led to altered protein binding and markedly decreased luciferase activity. Cloned into a promoterless luciferase vector, a 123 bp intron 1 fragment was able to direct reporter gene expression to the same activity as occurred in conjunction with the 5' flanking region. These results indicate that sequence elements in intron 1 are necessary for efficient transcription of hAT2. In reporter gene assays, intron 1 might by itself function as a promoter and initiate transcription from an alternative start point.
...
PMID:Efficient transcription of the human angiotensin II type 2 receptor gene requires intronic sequence elements. 1022 54


1 2 3 4 5 6 7 8 9 Next >>

---