Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.14.14.3 (luciferase)
 38,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence indicates DNA methylation as a part of the regulatory machinery controlling mammalian gene expression. The human melanoma cell line HA-A expresses low levels of transforming growth factor alpha (TGF-alpha). TGF-alpha mRNA accumulated, however, in response to DNA demethylation induced by a nucleoside analog, 5-azacytidine (5-azaC). The importance of DNA methylation in the TGF-alpha promoter region was examined by a transient transfection assay with luciferase reporter plasmids containing a portion of the TGF-alpha promoter. 5-azaC treatment of HA-A cells before the transfection caused a significant increase in the luciferase activity. Since input plasmids were confirmed to remain unmethylated, DNA demethylation of the TGF-alpha promoter itself does not account for the observed increase in TGF-alpha mRNA. Using an electrophoretic mobility shift assay, enhanced formation of protein-TGF-alpha promoter complex was detected in response to 5-azaC treatment. This 5-azaC-induced complex was shown to contain the transcription factor Sp1 by the following criteria: the protein-DNA complex formed on the TGF-alpha promoter contained immunoreactive Sp1; the mobility of the complex in an electrophoretic mobility shift assay was similar to that formed by recombinant Sp1; and DNase I footprinting analysis demonstrated that the 5-azaC-induced complex produced a footprint on the TGF-alpha promoter identical to that of authentic Sp1. These observations suggest that 5-azaC induces TGF-alpha expression by augmenting the Sp1 activity. However, neither the Sp1 mRNA nor its protein was induced by 5-azaC. These results suggest that in HA-A cells, TGF-alpha expression is down-modulated by DNA methylation. In addition, this process may involve the specific regulation of Sp1 activity without altering the amount of the transcription factor.
 ...
PMID:5-Azacytidine treatment of HA-A melanoma cells induces Sp1 activity and concomitant transforming growth factor alpha expression. 138 Jun 48

The insulin-like growth factor I receptor (IGF-I-R) gene is expressed in most body tissues. The levels of IGF-I-R mRNA, however, are regulated by a number of physiological conditions (development, differentiation, and hormonal milieu) as well as in certain pathological states (diabetes and tumors). To understand the molecular mechanisms which control the transcription of the IGF-I-R gene, we have cloned the promoter of the rat receptor gene and have characterized its activity by transient expression assays. Different fragments of the 5'-flanking region (subcloned upstream of a luciferase reporter gene) were transfected into buffalo rat liver 3A cells (a cell line with a low number of IGF-I binding sites) and Chinese hamster ovary cells (a cell line with a higher number of cell-surface receptors). In both cell lines, most of the promoter activity was located in the proximal 416 base pairs of 5'-flanking region. However, further dissection of this proximal fragment revealed a cell type-specific pattern of promoter activity. Thus, in buffalo rat liver 3A cells, subfragments of this region each contributed to total activity, suggesting that contiguous cis-elements can act together to activate transcription. In Chinese hamster ovary cells, on the other hand, subfragments of the proximal promoter region partially substituted for the proximal 416 base pairs of 5'-flanking region. Coexpression studies using an IGF-I-R promoter reporter construct together with an Sp1 expression vector (under the control of an ADH promoter) were performed in SL2 cells, a Drosophila cell line which lacks endogenous Sp1. The results obtained showed that Sp1 can trans-activate the IGF-I-R promoter in vivo. Transient transfection assays were complemented with gel-retardation assays and DNase I footprinting experiments, which showed that transcription factor Sp1 is potentially an important regulator of IGF-I-R gene expression.
 ...
PMID:Structural and functional analysis of the insulin-like growth factor I receptor gene promoter. 144 10

We have investigated the regulation of the expression of two growth factors found in vascular smooth muscle, transforming growth factor alpha (TGF alpha) and basic fibroblast growth factor (bFGF). Cells cultured in medium containing 30 mM glucose exhibited a 2-fold increase in TGF alpha mRNA and a 3-fold increase in bFGF mRNA compared with cells grown in normal (5.5 mM) glucose. Glucosamine was more potent than glucose, leading to a 6-fold increase in TGF alpha mRNA. TGF alpha protein levels were also increased by glucosamine treatment, and the predominant species present was the membrane-bound precursor form of TGF alpha. To examine further the regulation of growth factors by sugars, cultured rat aortic smooth muscle cells were transfected with a plasmid construct consisting of a 1.2-kilobase-pair fragment of the TGF alpha promoter linked to a luciferase reporter gene. Increasing the concentration of glucose in the culture medium from 5.5 mM to 30 mM led to a rapid, 1.7-fold increase in the activity of the TGF alpha promoter. Glucosamine was much more potent than glucose in this stimulation, with 2 mM glucosamine causing a 12-fold increase in TGF alpha promoter activity. Insulin had no effect on luciferase activity in either the presence or the absence of added sugars. The glucose response element of the TGF alpha gene maps to a 130-base-pair segment that includes three potential binding sites for the transcription factor Sp1. We conclude that high glucose concentrations such as are reached in diabetes mellitus can stimulate the transcription of the genes for growth factors in vascular smooth muscle cells. This signaling pathway apparently involves the metabolism of glucose to glucosamine. This effect could be representative of nutritional regulation of a family of genes and could contribute to the toxicity of hyperglycemia and the vascular complications of diabetes.
 ...
PMID:Glucose and glucosamine regulate growth factor gene expression in vascular smooth muscle cells. 151 40

The gene encoding fatty acid synthase, the essential multi-functional enzyme of fatty acid biosynthesis, is shown to be regulated by cellular sterol levels similar to genes that encode important proteins of cholesterol metabolism. We show that expression of the endogenous FAS gene is repressed when regulatory sterols are included in the culture medium of HepG2 cells and that the FAS promoter is subject to similar regulation when fused to the luciferase reporter gene. Mutational studies demonstrate that sterol regulation is mediated by binding sites for the sterol regulatory element-binding protein (SREBP) and transcription factor Sp1, making it mechanistically similar to sterol regulation of the low density lipoprotein receptor gene. It is also demonstrated that SREBP and Sp1 synergistically activate the FAS promoter in Drosophila tissue culture cells, which lack endogenous Sp1. These experiments provide key molecular evidence that directly links the metabolism of fatty acids and cholesterol together.
 ...
PMID:Sterol regulation of fatty acid synthase promoter. Coordinate feedback regulation of two major lipid pathways. 759 29

Insulin-like growth factor-binding protein-2 (IGF-BP-2) transcription in rat liver varies with developmental age and fasting. To define the DNA elements required for efficient expression of the TATA-less rat IGFBP-2 gene, the native or mutated promoter was fused to a promoterless luciferase reporter gene and transfected into BRL-3A rat liver and 293 human embryonic kidney cell lines. Luciferase activity decreased approximately 25-fold with progressive 5' promoter deletions from nucleotide (nt) -581 to nt -189 (relative to ATG, +1). The smallest construct, however, still had > 21-fold greater luciferase activity than the promoterless construct. In DNase I foot-printing assays using native nt -276 to -36 promoter fragments or fragments containing block substitution mutations, BRL-3A nuclear extract and purified human transcription factor Sp1 protected a region from nt -234 to -215 containing one GC box and a broad region from nt -189 to -125 that contained three clustered but independent GC boxes. In gel retardation assays using an Sp1 oligonucleotide probe, BRL-3A extract formed two closely migrating complexes that were immunologically related to Sp1; Sp1 gave a single complex that co-migrated with the more retarded BRL-3A complex. Binding was competitively inhibited by oligonucleotides corresponding to each of the four GC boxes. The proximal three GC boxes were sufficient to allow trans-activation of the IGFBP-2 promoter by Sp1 in Drosophila SL2 cells. Independent block mutations indicated that all three of the GC boxes are required for promoter activity and are equally important. Thus, binding of Sp1 or Sp1-related proteins to three clustered GC boxes in the proximal IGFBP-2 promoter is essential for promoter activity. Multiple upstream regions also contribute to the full expression of the IGFBP-2 gene.
 ...
PMID:Three clustered Sp1 sites are required for efficient transcription of the TATA-less promoter of the gene for insulin-like growth factor-binding protein-2 from the rat. 769 8

We have investigated the genetic basis of the transcriptional regulation of the rat connexin32 gene which encodes the major gap junction protein in rat liver. Primer extension analysis of RNA isolated from adult rat liver identified multiple initiation sites clustered between -110 bp and -50 bp upstream from the translation start codon. An approx. 760 bp genomic DNA fragment upstream of the first exon which included the mRNA start sites was cloned 5' to the luciferase reporter cassette in p19LUC to yield pCx32-800/-33-LUC. Transfection of pCx32-800/-33-LUC resulted in a 200-fold increase in luciferase activity above p19LUC in the human hepatoma cell line HuH-7. Using a series of vectors containing 5' deletions of the 760 bp fragment, a basal promoter was localized between -179 bp and -134 bp. Three DNA:protein complexes were identified with the basal promoter fragment by DNA mobility shift assay using nuclear extracts from HuH-7 cells. Two of the DNA-binding complexes appeared to be related to the transcription factor Sp1. In addition, three DNase hypersensitive (HS) sites were identified within the genomic locus of connexin32 in adult rat liver. Two of the DNase HS regions behaved as silencer elements with both the native promoter and a heterologous promoter in HuH-7 cells. These data demonstrate that (1) the active promoter responsible for rat connexin32 mRNA transcription is located upstream of the first exon, (2) a basal promoter region was localized to a 50 bp region which formed multiple DNA:protein complexes, and (3) multiple proximal and distant regulatory elements are involved in the expression of connexin32.
 ...
PMID:Identification of proximal and distal regulatory elements of the rat connexin32 gene. 824 Dec 60

Gene expression of the cancer-associated human papillomavirus (HPV) type 18 is modulated by cis-regulatory elements located within the viral upstream regulatory region (URR). All cellular factors identified so far involved in viral gene control bind to the 3' portion of the HPV-18 URR. In contrast, very little is known about regulatory elements within the 5' portion of the URR. We therefore analysed this region of unknown function to delineate potential cis-regulatory elements contained therein. By utilizing transient expression assays, an 84 bp fragment could be identified in the 5' portion of the URR that exhibits orientation-independent cis-stimulatory activity in HeLa cervical carcinoma cells and primary human fibroblasts. Gel retardation assays and competition experiments indicated specific binding of cellular proteins to the 84 bp fragment. By functional dissection, a regulatory element with intrinsic cis-stimulatory activity could be mapped within the 84 bp fragment. Binding studies indicate that this cis-stimulatory element contains a sequence-aberrant Sp1 recognition site. Transient luciferase assays performed with mutated templates demonstrate that this Sp1 binding site behaves as a functional Sp1 element in vivo and is a main determinant of the cis-stimulatory activity exerted by the 84 bp fragment. These data show that the 5' portion of the HPV-18 URR contains cis-activating elements and indicate an important functional role for the cellular transcription factor Sp1 in their regulation.
 ...
PMID:A novel cis-stimulatory element maps to the 5' portion of the human papillomavirus type 18 upstream regulatory region and is functionally dependent on a sequence-aberrant Sp1 binding site. 838 69

The authors have identified two types of hippocampal cDNAs for the rat mineralocorticoid receptor (rMR) which are identical in the protein coding domain but differ in their 5'-untranslated sequences. One of these clones encodes a novel type of rMR cDNA with a high homology to a previously described human MR cDNA isolated from the kidney. A genomic clone containing the 5'-end of the rat MR gene was isolated. The 12.7 kb genomic region contains the 5'-coding exon with the translational start site and contiguous DNA sequences encoding the N-terminal domain of the rMR. A 240 bp region homologous to the 5'-untranslated sequences of the novel rMR cDNA was located 5.2 kb upstream the protein coding region. Characterization of the nucleotide sequence preceding this exon revealed several features characteristic for promoters of so-called 'housekeeping genes'. The sequence analyzed is 635 bp in length, is rich in G+C nucleotides (63%) and lacks TATA or CAAT regulatory elements. It contains three putative binding sites for transcription factor Sp1 as well as several short sequences that are similar to known cis-acting enhancers or binding sites for transcription factors. In transient transfection experiments employing the luciferase reporter gene and the CV1 cell line this region exhibits substantial promoter activity. These experiments demonstrate that expression of the rat MR gene in the hippocampus results in at least two transcripts with different 5'-untranslated exons.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:A functional promoter directing expression of a novel type of rat mineralocorticoid receptor mRNA in brain. 840 70

Genomic clones containing the gene for the glutathione peroxidase-like androgen-regulated murine epididymal protein of 24 kilodaltons (arMEP24) were isolated. A 9-kilobase DNA fragment was sequenced and found to contain the entire coding region of the gene, which is divided into five exons. The exact sizes and boundaries of the exon blocks were deduced by comparison with the cDNA sequence. One major and four weak transcription initiation sites in the epididymis were localized by primer extension. The promoter of the gene does not contain a conventional TATA box immediately up-stream of the start site; rather, the sequence TATCA occurs at residue -35. Two CAAT boxes in opposite orientation and two putative binding sites for the transcription factor Sp1 were identified up-stream of the TATA-like box. To localize the cis-acting sequences responsible for androgen regulation of expression, fragments of the arMEP24 gene promoter region were cloned in front of the luciferase (LUC) reporter gene and cotransfected with an androgen receptor expression vector into CV-1 cells in a transient assay. LUC activities of CV-1 cells grown in the presence of various concentrations of 5 alpha-dihydrotestosterone were compared to LUC activities of untreated controls. The DNA fragment containing up to 200 nucleotides up-stream from the major transcription start site was sufficient for the full promoter activity, but not for the responsiveness to androgen induction. Depending on the 5 alpha-dihydrotestosterone concentration, a 2- to 4-fold induction of LUC activity was found if a -1797 to -167 arMEP24 gene fragment was used linked to the reporter gene driven by either the homologous promoter or the heterologous thymidine kinase promoter. Two or three copies of the imperfect palindromic sequence TGTTGAgagAGAACA, found at position -896 to -882 in the gene and resembling the consensus steroid hormone-responsive element, are able to confer androgen regulation to the thymidine kinase promoter independently of their orientation. These findings support evidence that transcriptional regulation of the arMEP24 gene occurs via the sequence TGTTGAgagAGAACA. Homologies found in the sequence up-stream of the promoter with several putative binding sites for erythroid-specific trans-acting regulatory proteins are discussed. Finally, the arMEP24 gene is located by in situ hybridization in the [A2-A4] region of mouse chromosome 13.
 ...
PMID:Structural organization and regulation of the gene for the androgen-dependent glutathione peroxidase-like protein specific to the mouse epididymis. 846 39

We have identified a rare mutation (T-45C) in the low density lipoprotein (LDL)-receptor gene in a Welsh patient with a clinical diagnosis of heterozygous familial hypercholesterolaemia (FH). The mutation is in the proximal Sp1 binding site in repeat 3 of the 42 bp region of the promoter required for sterol-dependent regulation of transcription, but the substituted nucleotide is not a strongly conserved base in the consensus sequence for Sp1 binding. Normal and mutant promoter fragments (from base -600 to -5) were linked to a luciferase reporter gene, and transient expression in COS cells showed that the mutation reduced transcriptional activity to approximately 43% of normal in the presence, and 25% in the absence of sterols in the medium. Competitive gel-shift mobility assays showed that the mutation reduced the binding affinity for transcription factor Sp1. Analysis of a neutral polymorphism in the LDL-receptor mRNA from the patient's lymphoblasts showed that expression of one allele was reduced. Since Southern blotting of genomic DNA and sequencing of the entire coding region of the LDL-R gene did not reveal any other potential defects, we infer that the T-45 C mutation is the underlying cause of hypercholesterolaemia in the proband.
 ...
PMID:A mutation (T-45C) in the promoter region of the low-density-lipoprotein (LDL)-receptor gene is associated with a mild clinical phenotype in a patient with heterozygous familial hypercholesterolaemia (FH). 858 90


1 2 3 4 5 6 7 8 Next >>