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At least 487 records · Page 27Linked to original sources
PubMed1998

Thyroid hormone direct repeat 4 response element is a positive regulatory element for the human TR2 orphan receptor, a member of steroid receptor superfamily.

We demonstrate that TR2 orphan receptor (TR2) may induce transactivation activities via an AGGTCA-like-direct-repeat-4 consensus thyroid hormone response element (DR4-TRE) system. TR2 showed a slightly greater binding affinity than thyroid hormone receptor alpha1 (TR alpha1)/retinoid X receptor alpha (RXR alpha) heterodimer with Kds 0.5 nM and 2.3 nM, respectively. These receptors, TR2 and TR alpha1/RXR alpha heterodimer, competed with each other on binding to limited amounts of DR4-TRE. TR2 canceled the suppression effect of unliganded-TR alpha1 on CAT reporter activity in a dose-dependent fashion. Estrogen receptor (ER) and 2P2 (a mutated TR2 with P box sequence of androgen receptor) failed not only to bind to DR4-TRE but also to recover this inhibitory effect of unliganded TRalpha1. However, when T3 was supplemented, estradiol-ER competed for a full CAT activity while TR2 showed an additive effect on the transcriptional activation. These results indicate that DNA binding is essential for TR2 to take action and fully functional liganded TR alpha1 may rely on common factors shared with ER but not TR2.

Carrier Proteins↗
PubMed1996

Enhancer analysis of the mouse HNF-3 beta gene: regulatory elements for node/notochord and floor plate are independent and consist of multiple sub-elements.

BACKGROUND: Axial pattern formation in vertebrate embryos depends on signals from the node and, later, from the notochord and floor plate. Previous studies have shown that HNF-3 beta, a member of the winged-helix transcription factor family, plays key roles in the development of all three organizing centres. RESULTS: Enhancer analysis of HNF-3 beta has therefore been performed using lacZ reporter gene constructs in transgenic mouse embryos. This has led to the identification of independent node/notochord and floor plate enhancers, at positions far upstream (-15 to -14 kb) and downstream (+6 to +11 kb) of the transcription star site, respectively. The node/notochord enhancer activity has been localized to a 520 bp fragment. Floor plate gene expression requires a combination of two separate fragments of the enhancer. Deletion analysis of one of these fragments (400 bp) has identified subregions required for the initiation and the maintenance of floor plate expression, and for the suppression of ectopic expression within the neural tube. CONCLUSION: We conclude that HNF-3 beta gene expression in the node/notochord and in the floor plate are controlled through different enhancers, which consist of positive and negative elements.

Animals↗
PubMed2000

Nutritional regulation of the fatty acid synthase promoter in vivo: sterol regulatory element binding protein functions through an upstream region containing a sterol regulatory element.

The transcription of fatty acid synthase (FAS), a central enzyme in de novo lipogenesis, is dramatically induced by fasting/refeeding and insulin. We reported that upstream stimulatory factor binding to the -65 E-box is required for induction of the FAS transcription by insulin in 3T3-L1 adipocytes. On the other hand, we recently found that two upstream 5' regions are required for induction in vivo by fasting/refeeding and insulin; one at -278 to -131 albeit at a low level, and the other at -444 to -278 with an E-box at -332 where upstream stimulatory factor functions for maximal induction. Here, we generated double transgenic mice carrying the chloramphenicol acetyltransferase reporter driven by the various 5' deletions of the FAS promoter region and a truncated active form of the sterol regulatory element (SRE) binding protein (SREBP)-1a. We found that SREBP participates in the nutritional regulation of the FAS promoter and that the region between -278 and -131 bp is required for SREBP function. We demonstrate that SREBP binds the -150 canonical SRE present between -278 and -131, and SREBP can function through the -150 SRE in cultured cells. These in vivo and in vitro results indicate that SREBP is involved in the nutritional induction of the FAS promoter via the -278/-131 region and that the -150 SRE is the target sequence.

3T3 Cells↗
PubMed1998

Copy number control of a transposable element, the I factor, a LINE-like element in Drosophila.

The I factor is a LINE-like transposable element in Drosophila. Most strains of Drosophila melanogaster, inducer strains, contain 10-15 copies of the I factor per haploid genome located in the euchromatic regions of the chromosome arms. These are not present in a few strains known as reactive strains. I factors transpose at low frequency in inducer strains but at high frequency in the female progeny of crosses between reactive and inducer flies. We have found that the activity of the I factor promoter is sensitive to the number of copies of the first 186 nucleotides of the I factor sequence, which constitutes the 5'-untranslated region. The activity of the I factor decreases as the copy number of this sequence increases.

Animals↗
PubMed1995

The rat quinone reductase antioxidant response element. Identification of the nucleotide sequence required for basal and inducible activity and detection of antioxidant response element-binding proteins in hepatoma and non-hepatoma cell lines.

The antioxidant response element (ARE) found in the 5'-flanking region of the rat quinone reductase gene has been further characterized by mutational and deletion analysis. The results indicate that the 31-base pair ARE, which contains a 13-base pair palindromic sequence, can be further separated into three regions, all three of which are required for elevated basal level gene expression. These three regions include the proximal and distal half-sites as well as a 3'-flanking region consisting of 4 adenine nucleotides. Neither the proximal nor the distal half-site alone mediates transcriptional activation by beta-naphthoflavone. However, when placed together the two half-sites restore responsiveness to the inducer. Interestingly, the presence of only 1 of the 4 adenine nucleotides in the 3'-flanking region of the proximal half-site is required for responsiveness to the inducer. Point mutations within the ARE indicate that several nucleotides in both the proximal and distal half-sites are required for basal level gene expression. Electrophoretic mobility shift analysis using the ARE as the probe indicates that enhancers found in the glutathione S-transferase Ya and P genes recognize a similar trans-acting factor(s) found in crude nuclear extracts from human Hep G2 cells. Further, this complex can be detected in nuclear extracts from rat liver and rat hepatoma cells but not in mouse Hepa 1c1c7 cells or in human HeLa cells. The ARE-nucleoprotein complex can also be detected in F9 cells which lack significant levels of Jun/Fos proteins. Although the rat ARE resembles the human quinone reductase ARE which contains a consensus TRE, the 2-nucleotide change in the core sequence (TGACTCA versus TGACTTG) eliminates the high affinity TRE motif in the rat ARE. The rat ARE forms a nucleoprotein complex in Hep G2 and other cells with different properties than AP-1.

Animals↗
PubMed1998

Gene-specific transcriptional activity of the insulin cAMP-responsive element is conferred by NF-Y in combination with cAMP response element-binding protein.

Cyclic AMP stimulates insulin gene transcription through a cAMP response element (CRE). In the present study the insulin CRE-binding proteins and their functions were investigated. A mutational analysis of nuclear protein binding in electrophoretic mobility shift assays in combination with specific antisera showed that in the CRE of the rat insulin I gene the imperfect CRE octamer-like sequence TGACGTCC interacts weakly with CREB and overlaps with two sequence motifs (TTGTTGAC and CCAAT) that bind winged helix-like proteins and the transcription factor NF-Y, respectively. Transient transfection of wild-type and mutant insulin CRE-reporter fusion genes and the inactivation of cellular CREB or NF-Y by overexpression of the dominant negative mutants KCREB or NF-YA29, respectively, indicate that cAMP inducibility of the insulin CRE is mediated by CREB or closely related proteins; however, NF-Y binding to the insulin CRE confers constitutive, basal activity and decreases the ability of CREB to mediate cAMP-stimulated transcription and calcium responsiveness. Results from these studies demonstrate that NF-Y binds to the insulin CRE and modulates the function of CREB. Together with the nonpalindromic sequence of the CRE octamer motif, the interaction of NF-Y with CREB may be responsible for the gene-specific transcriptional activity of the insulin CRE and explain why it has considerable basal activity but is less responsive to cAMP stimulation than others.

Animals↗
PubMed2000

Validation of inductively coupled plasma atomic emission spectrometry technique (ICP-AES) for multi-element analysis of trace elements in human serum.

The use of inductively coupled plasma atomic emission spectrometry (ICP-AES) for the simultaneous determination of Al, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Se, Sr and Zn in human serum in a clinical laboratory was validated. Samples were digested and then analysed using yttrium as an internal standard and a serum-matched calibration standard. The criteria used to assess the analytical performance of the ICP-AES were detection and quantification limits, linearity, sensitivity, recovery, interference from alkali and acid, trueness and precision. Detection limits were 0.002-0.003 micromol/L for Mn, Sr, Ba, and Cd; 0.014-0.07 micromol/L for Co, Zn, Fe, Be, Li, Pb, Cu, Ni, and Cr; and 0.2-0.9 micromol/L for B, Se, and Al. Trueness, as controlled by analysis of bovine serum certified reference material, was acceptable for Co, Cu, Se and Zn, while Fe was 5.1% and Mn 6.2% below the lowest limit of the certified material interval. We conclude that ICP-AES can be used for multi-element analysis of B, Ba, Cu, Fe, Li, Se, Sr and Zn in serum. Serum levels of Al, Be and Co were below the detection limits while serum levels of Cd, Cr, Ni and Pb were below the quantification limits of the ICP-AES. These trace metals cannot be analysed as routine by the ICP-AES. However, in cases of intoxication with elevated serum concentrations mean recovery of 100+/-10% was obtained at an addition of 2.22 micromol/L for Al, 0.11 micromol/L for Be, 0.03 micromol/L for Co, 0.39 micromol/L for Cr, 0.14 micromol/L for Ni, and 0.12 micromol/L for Pb.

Calibration↗
PubMed2001

Cofactor requirements for nuclear export of Rev response element (RRE)- and constitutive transport element (CTE)-containing retroviral RNAs. An unexpected role for actin.

Nuclear export of proteins containing leucine-rich nuclear export signals (NESs) is mediated by the export receptor CRM1/exportin1. However, additional protein factors interacting with leucine-rich NESs have been described. Here, we investigate human immunodeficiency virus type 1 (HIV-1) Rev-mediated nuclear export and Mason-Pfizer monkey virus (MPMV) constitutive transport element (CTE)-mediated nuclear export in microinjected Xenopus laevis oocytes. We show that eukaryotic initiation factor 5A (eIF-5A) is essential for Rev and Rev-mediated viral RNA export, but not for nuclear export of CTE RNA. In vitro binding studies demonstrate that eIF-5A is required for efficient interaction of Rev-NES with CRM1/exportin1 and that eIF-5A interacts with the nucleoporins CAN/nup214, nup153, nup98, and nup62. Quite unexpectedly, nuclear actin was also identified as an eIF-5A binding protein. We show that actin is associated with the nucleoplasmic filaments of nuclear pore complexes and is critically involved in export processes. Finally, actin- and energy-dependent nuclear export of HIV-1 Rev is reconstituted by using a novel in vitro egg extract system. In summary, our data provide evidence that actin plays an important functional role in nuclear export not only of retroviral RNAs but also of host proteins such as protein kinase inhibitor (PKI).

Actins↗
PubMed1989

Recent developments in trace element metabolism and function: trace elements, disease resistance and immune responsiveness in ruminants.

Evidence for the influence of trace elements on disease resistance in ruminants is reviewed with emphasis on susceptibility to infection in vivo during the more common deficiencies (copper, selenium and cobalt). Copper deficiency associated with increases in pasture molybdenum increased the susceptibility of lambs to microbial infections. Under experimental conditions, dietary molybdenum decreased the establishment of abomasal and intestinal nematodes but not their pathogenicity to lambs. Molybdenum may enhance inflammatory responses leading to parasite rejection by the host. Decreased incidence of metritis in selenium-treated dairy cows provides a rare example of an association between selenium deficiency and decreased disease resistance. Improved antibody responses following selenium administration have also been found in sheep. Cobalt deficiency has reduced lamb survival and increased susceptibility to parasitic infection transiently in cattle and lastingly in sheep. In copper-, selenium- or cobalt-deficient sheep and cattle, there are many reports of impaired leucocyte and lymphocyte responses to in vitro challenges, but their relevance to disease resistance in vivo is unproven. Disease resistance may have priority for limited micronutrient supplies, leaving other processes vulnerable.

Animals↗
PubMed2006

FAIRE (Formaldehyde-Assisted Isolation of Regulatory Elements) isolates active regulatory elements from human chromatin.

DNA segments that actively regulate transcription in vivo are typically characterized by eviction of nucleosomes from chromatin and are experimentally identified by their hypersensitivity to nucleases. Here we demonstrate a simple procedure for the isolation of nucleosome-depleted DNA from human chromatin, termed FAIRE (Formaldehyde-Assisted Isolation of Regulatory Elements). To perform FAIRE, chromatin is crosslinked with formaldehyde in vivo, sheared by sonication, and phenol-chloroform extracted. The DNA recovered in the aqueous phase is fluorescently labeled and hybridized to a DNA microarray. FAIRE performed in human cells strongly enriches DNA coincident with the location of DNaseI hypersensitive sites, transcriptional start sites, and active promoters. Evidence for cell-type-specific patterns of FAIRE enrichment is also presented. FAIRE has utility as a positive selection for genomic regions associated with regulatory activity, including regions traditionally detected by nuclease hypersensitivity assays.

Cells, Cultured↗
PubMed1995

Homeotic response elements are tightly linked to tissue-specific elements in a transcriptional enhancer of the teashirt gene.

Along the anterior-posterior axis of animal embryos, the choice of cell fates, and the organization of morphogenesis, is regulated by transcription factors encoded by clustered homeotic or 'Hox' genes. Hox genes function in both epidermis and internal tissues by regulating the transcription of target genes in a position- and tissue-specific manner. Hox proteins can have distinct targets in different tissues; the mechanisms underlying tissue and homeotic protein specificity are unknown. Light may be shed by studying the organization of target gene enhancers. In flies, one of the target genes is teashirt (tsh), which encodes a zinc finger protein. tsh itself is a homeotic gene that controls trunk versus head development. We identified a tsh gene enhancer that is differentially activated by Hox proteins in epidermis and mesoderm. Sites where Antennapedia (Antp) and Ultrabithorax (Ubx) proteins bind in vitro were mapped within evolutionarily conserved sequences. Although Antp and Ubx bind to identical sites in vitro, Antp activates the tsh enhancer only in epidermis while Ubx activates the tsh enhancer in both epidermis and in somatic mesoderm. We show that the DNA elements driving tissue-specific transcriptional activation by Antp and Ubx are separable. Next to the homeotic protein-binding sites are extensive conserved sequences likely to control tissue activation by different homeodomain proteins. We propose that local interactions between homeotic proteins and other factors effect activation of targets in proper cell types.

Animals↗
PubMed1989

[Changes in trace-element concentrations after intravenous injection of an essential trace-element preparation for parenteral use in rats].

This experiment was carried out to investigate the effects of intravenous injection of an essential trace-element preparation (TE-5) on iron, zinc, copper and manganese concentrations, and blood biochemical and hematological parameters in rats. The rats were treated by intravenous injection of TE-5 for 7 days and the following results were obtained: 1) Neither a 0.04 nor a 0.4 ml/kg/day injection of TE-5 affected the iron, zinc, copper and manganese concentrations in tissues. 2) At a higher dose (1.2 ml/kg/day), iron concentrations in liver and spleen, zinc concentrations in liver, kidney, tibia and plasma, copper concentrations in heart, kidney and whole blood, and manganese concentrations in brain, heart, spleen, kidney, femoral muscle, tibia and whole blood increased. 3) At the highest does (4 ml/kg/day), all rats died and iron, zinc, copper and manganese concentrations in tissues increased remarkably. 4) With injections of TE-5 (0.04-1.2 ml/kg/day), hemoglobin, hematocrit, alkaline phosphatase activity and blood urea nitrogen decreased slightly. These results suggest that iron, zinc, copper and manganese concentrations, and blood biochemical and hematological parameters are maintained at doses up to 0.4 ml/kg/day of TE-5, but that doses higher than that destroy homeostasis.

Animals↗
PubMedDate not supplied

[The structure of the transposable genetic element ISBsu2 in the cryptic plasmid p1516 from a soil Bacillus subtilis strain and the presence of homologues of this element in the chromosomes of various Bacillus subtilis strains].

A cryptic plasmid from a soil strain of Bacillus subtilis was found to contain a sequence having features of IS element. Homologous sequences were also found in the chromosome of this strain and in the chromosomes of some other B. subtilis strains.

Bacillus subtilis↗
PubMed1991

[Trace element deficiency in healthy subjects based on multi-element analysis of serum and plasma].

Among other elements (manganese, molybdenum, cadmium, mercury, lead, nickel), the levels of selenium in healthy human sera (n = 56) and plasma (n = 15) were measured by ICP spectrometry. It was ascertained by the multielement analysis that of 40 nineteen year-old males (from 28 different villages in one county 15 showed lower than detectable levels of selenium in their sera (n = 25) and plasma (n = 15) samples. For this reason, the selenium contents of the sera of 31 blood donors were determined by the ICP spectrometry, with hybrid generation. By this same technique the selenium in sera of 16 men aged between 24-60 years (mean = 43.3 years) was measured as 24.06 micrograms/l (13-42 micrograms/l), while in 15 women between the ages of 19-64 years (mean 39.3 years) it amounted to 20.86 micrograms/l (11-31 micrograms/l). In 28 cases from 40 samples (25 sera and 15 plasma) the concentration of molybdenum was smaller than the detectable limit (less than 0.0011 mg/l). Firstly, these results prove that amongst healthy individuals, in Hungary, molybdenum and selenium deficiency states exist. The authors conclude that there is a relationship between these deficiency states, as risk factors, and the frequently occurring diseases (malignant tumours, cardiovascular diseases, etc.) in Hungary.

Humans↗
PubMed1986

A study of seasonal trace element intakes and hair trace element concentrations in selected households from the Wosera, Papua New Guinea.

The trace element status of nine households from the Wosera subdistrict of Papua New Guinea was assessed. Individual weighed three-day dietary intakes were carried out in April during the hungry season when yams were not eaten and in July when yams were available. Representative staple food items analyzed 'as eaten' for energy, protein, Ca, Mn, Cu and Zn and mean daily energy and nutrient intakes calculated. Hair samples were also collected in July, washed, and analyzed for Zn, Cu and Mn by INAA. Seasonal differences in energy, protein, Ca, Fe and Mn intakes were related to changes in yam consumption. The Zn status of the male (M) and female (F) adults and children (Ch) was sub-optimal based on low median hair Zn levels (microgram/g): -F = 78, n = 8; M = 108, n = 8; Ch2-4yrs = 79, n = 8; Ch5-10yrs = 94, n = 7 and inadequate intakes of readily available Zn (mean + SD): - April M + F = 7.0 + 1.6 mg/day; July M + F = 8.2 + 1.5 mg/day; less than three percent Zn from animal products. In contrast their Mn status, as indicated by elevated median hair Mn levels (microgram/g) (F = 25.1; M = 26.3; Ch2-4yrs = 21.5; Ch5-10yrs = 15.2) was high, attributed to elevated Mn intakes (April M + F = 11.0 + 2.2 mg/day; July M + F = 7.5 + 1.4 mg/day). Median hair Cu levels (microgram/g) (F = 7.6; M = 7.5; Ch2-4yrs = 8.6; Ch5-10yrs = 7.8) and mean Cu intakes (April M + F = 2.2 + 0.4 mg/day; July M + F = 3.0 + 0.6 mg/day) were within the range noted for persons consuming predominantly plant-based diets.

Adult↗
PubMed1995

Inhibition by antidepressant drugs of cyclic AMP response element-binding protein/cyclic AMP response element-directed gene transcription.

Clinical observations agree that antidepressant drugs are effective only after a lag phase of 1-3 weeks. This delay could be explained at the molecular level by an action on gene transcription. Transcription of many genes is directed by the cAMP/Ca(2+)-responsive element (CRE) and its cognate transcription factor CRE-binding protein (CREB). Membrane depolarization and cAMP induce the phosphorylation of CREB at Ser-119 and thereby stimulate the transcriptional activity of CREB. The effect of antidepressant drugs on CREB/CRE-directed gene transcription was investigated using transient transfections of reporter fusion genes in HIT and PC-12 cells. Clomipramine, imipramine, fluoxetine, doxepin, desipramine, amitriptyline, maprotiline, mianserin, and trazodone inhibited CRE-directed gene transcription that was stimulated by membrane depolarization, with IC50 values between 70 nM and 1.73 microM. Desipramine had no effect on transcription after stimulation by cAMP but blocked the synergistic effect of cAMP and membrane depolarization to the level of stimulation by cAMP alone. Upon membrane depolarization, desipramine reduced the phosphorylation of CREB at Ser-119 and also blocked the depolarization-induced increase in the intracellular free Ca2+ concentration in HIT cells. Thus, by interfering with the depolarization-induced activation of the transcription factor CREB, antidepressant drugs can inhibit CRE-directed gene transcription, which could underlie the pharmacological effects of these clinically important drugs.

Animals↗
PubMed1985

Transcriptional antitermination activity of the synthetic nut elements of coliphage lambda. I. Assembly of the nutR recognition site from boxA and nut core elements.

An active nutR antiterminator was reconstructed from two synthetic modules, one containing the 8-bp boxA (5'-CGCTCTTA) and the other the 17-bp nutR core (5'-AGCCCTGAAAAAGGGCA) sequence. The modules were synthesized with HindIII cohesive ends, which upon annealing and ligation created an 8-bp spacer (5'-CAAAGCTT) between the boxA and nutR core. The 8-bp length was the same as in the native nutR (5'-CACATTCC), but the sequence showed less than 38% homology. The antitermination mediated by the synthetic nutR, was 68-80% efficient when tested in the pp-nutR-N-tL1-galK expression plasmid, analogous to that used by Drahos and Szybalski [Gene, 16 (1981) 261-274]. The cloned boxA by itself has no activity, while the nutR core alone shows only marginal (5-10%) antiterminator function. Increasing the distance between boxA and the nutR core from 8 bp to 20-28 bp, i.e., by one to two turns of the DNA helix (about 10 bp per turn), has little effect on the antiterminator function, whereas use of spacers with length about halfway between 8 and 20 bp results in reduced antitermination. It appears that both the sequences and spacial arrangement of the boxA and nut elements are important for efficient antiterminator function.

Bacterial Proteins↗
PubMed1986

Transcriptional antitermination activity of the synthetic nut elements of coliphage lambda. I. Assembly of the nutR recognition site from boxA and nut core elements.

An active nutR antiterminator was reconstructed from two synthetic modules, one containing the 8-bp boxA (5'-CGCTCTTA) and the other the 17-bp nutR core (5'-AGCCCTGAAAAAGGGCA) sequence. The modules were synthesized with HindIII cohesive ends, which upon annealing and ligation created an 8-bp spacer (5'-CAAAGCTT) between the boxA and nutR core. The 8-bp length was the same as in the native nutR (5'-CACATTCC), but the sequence showed less than 38% homology. The antitermination mediated by the synthetic nutR was 68-80% efficient when tested in the pp-nutR-N-tL1-galK expression plasmid, analogous to that used by Drahos and Szybalski [Gene, 16 (1981) 261-274]. The cloned boxA by itself has no activity, while the nutR core alone shows only marginal (5-10%) antiterminator function. Increasing the distance between boxA and the nutR core from 8 bp to 20-28 bp, i.e., by one to two turns of the DNA helix (about 10 bp per turn), has little effect on the antiterminator function, whereas use of spacers with length about halfway between 8 and 20 bp results in reduced antitermination. It appears that both the sequences and spacial arrangement of the boxA and nut elements are important for efficient antiterminator function.

Bacteriophage lambda↗