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PubMed1997

A novel proximal element mediates the regulation of mouse Ren-1C promoter by retinoblastoma protein in cultured cells.

The protein product of the retinoblastoma susceptibility gene, RB, is a nuclear phosphoprotein that modulates transcription of genes involved in growth control via interactions with transcription factors. Renin is a rate-limiting enzyme of the renin-angiotensin system that regulates blood pressure and water-electrolyte balance. Renin gene expression is regulated in a tissue-specific and developmentally linked manner. Similarly, the expression of RB is controlled in a differentiation-linked manner. Thus, to investigate whether RB is involved in the regulation of renin gene expression, we examined the effects of RB on transcriptional activity of the mouse renin (Ren-1C) promoter. The Ren-1C promoter contains two transcriptionally important elements; the RU-1 (-224 to -138) and RP-2 (-75 to -47) elements. RB activated the Ren-1C promoter in human embryonic kidney cells. The promoter element responsible for RB-mediated transcriptional regulation was the RP-2 element. The results of DNA-protein binding experiments showed that RB increased nuclear binding activity to the RP-2 element, and site-directed mutation which disrupted binding of nuclear factors to the RP-2 element markedly reduced RB-mediated activation of Ren-1C promoter in human embryonic kidney cells. These results indicate that the RP-2 element plays an important role in RB-mediated transcriptional regulation of Ren-1C promoter activity in human embryonic kidney cells, thereby suggesting an interesting mechanism by which RB may modulate the renin-angiotensin system.

Activating Transcription Factors↗
PubMed1998

Apolipoprotein(a) gene enhancer resides within a LINE element.

Apolipoprotein(a), (apo(a)), is the distinguishing protein portion of the lipoprotein(a) particle, elevated plasma levels of which are a major risk factor for cardiovascular disease. A search for enhancer elements that control the transcription of the apo(a) gene led to the identification of an upstream element that contains target binding sites for members of the Ets and Sp1 nuclear protein families. The enhancer element functions in either orientation to confer a greater than 10-fold increase in the activity of the apo(a) minimal promoter in cultured hepatocyte cells. Unexpectedly, the enhancer element is located within a LINE retrotransposon element, suggesting that LINE elements may function as mobile regulatory elements to control the expression of nearby genes.

Apolipoproteins↗
PubMed1998

Chondrocyte-specific enhancer elements in the Col11a2 gene resemble the Col2a1 tissue-specific enhancer.

Type XI collagen and type II collagen are coexpressed in all cartilage, and both are essential for normal cartilage differentiation and skeletal morphogenesis. This laboratory has recently identified a 48-base pair (bp) enhancer element in the type II collagen gene Col2a1 that contains several HMG-type protein-binding sites and that can direct chondrocyte-specific expression in transient transfection and in transgenic mice. The present study has identified two short chondrocyte-specific enhancer elements within a region in the 5' portion of the type XI collagen gene Col11a2 that has previously been shown to influence chondrocyte-specific expression in transgenic mice. These Col11a2 enhancer elements, like the Col2a1 enhancer, contain several sites with homology to the high mobility group (HMG) protein-binding consensus sequence. In electrophoretic mobility shift assays, the Col11a2 elements formed a DNA-protein complex that was dependent on the presence of the HMG-like sites. It had the same mobility as the complex formed with the Col2a1 48-bp enhancer and appeared to contain the same or similar proteins, including SOX9. The Col11a2 elements directed gene expression in transient transfections of chondrocytes but not fibroblasts, and their activity was abolished by mutation of the HMG-like sites. Ectopically expressed SOX9 activated these enhancers in non-chondrocytic cells, as it also activates the Col2a1 enhancer. Finally, the Col11a2 enhancer elements both directed transgene expression to cartilage in developing mouse embryos. Overall, our results indicate that the two Col11a2 chondrocyte-specific enhancer elements share many similarities with the Col2a1 48-bp enhancer. These similarities suggest the existence of a genetic program designed to coordinately regulate the expression of these and perhaps other genes involved in the chondrocyte differentiation pathway.

Animals↗
PubMed1999

One mechanism for cell type-specific regulation of the bax promoter by the tumor suppressor p53 is dictated by the p53 response element.

Key to the function of the tumor suppressor p53 is its ability to activate the transcription of its target genes, including those that encode the cyclin-dependent kinase inhibitor p21 and the proapoptotic Bax protein. In contrast to Saos-2 cells in which p53 activated both the p21 and bax promoters, in MDA-MB-453 cells p53 activated the p21 promoter, but failed to activate the bax promoter. Neither phosphorylation of p53 on serines 315 or 392 nor an intact C terminus was required for p53-dependent activation of the bax promoter, demonstrating that this differential regulation of bax could not be explained solely by modifications of these residues. Further, this effect was not due to either p73 or other identified cellular factors competing with p53 for binding to its response element in the bax promoter. p53 expressed in MDA-MB-453 cells also failed to activate transcription through the p53 response element of the bax promoter in isolation, demonstrating that the defect is at the level of the interaction between p53 and its response element. In contrast to other p53 target genes, like p21, in which p53-dependent transcriptional activation is mediated by a response element containing two consensus p53 half-sites, activation by p53 of the bax element was mediated by a cooperative interaction of three adjacent half-sites. In addition, the interaction of p53 with its response element from the bax promoter, as compared with its interaction with its element from the p21 promoter, involves a conformationally distinct form of the protein. Together, these data suggest a potential mechanism for the differential regulation of p53-dependent transactivation of the bax and p21 genes.

Base Sequence↗
PubMed2000

Insulin responsiveness of the glucagon gene conferred by interactions between proximal promoter and more distal enhancer-like elements involving the paired-domain transcription factor Pax6.

Regulation of gene transcription is an important aspect of insulin's action. However, the mechanisms involved are poorly understood. Insulin inhibits glucagon gene transcription, and insulin deficiency is associated with hyperglucagonemia that contributes to hyperglycemia in diabetes mellitus. Transfecting glucagon-reporter fusion genes into a glucagon-producing pancreatic islet cell line, a 5'-, 3'-, and internal deletion analysis, and oligonucleotide cassette insertions failed in the present study to identify a single insulin-responsive element in the glucagon gene. They rather indicate that insulin responsiveness depends on the presence of both proximal promoter elements and more distal enhancer-like elements. When the paired domain transcription factor Pax6 binding sites within the proximal promoter element G1 and the enhancer-like element G3 were mutated into GAL4 binding sites, the expression of GAL4-Pax6 and GAL4-VP16 restored basal activity, whereas only GAL4-Pax6 restored also insulin responsiveness. Likewise, GAL4-CBP activity was inhibited by insulin within the glucagon promoter context. The results suggest that insulin responsiveness is conferred to the glucagon gene by the synergistic interaction of proximal promoter and more distal enhancer-like elements, with Pax6 and its potential coactivator the CREB-binding protein being critical components. These data thereby support concepts of insulin-responsive element-independent mechanisms of insulin action to inhibit gene transcription.

Adenovirus E1B Proteins↗
PubMed1977

Balance study of twenty trace elements during total parenteral nutrition in man.

1. Balances of twenty trace elements (silver, arsenic, gold, bromine, cadmium, cobalt, chromium, caesium, copper, iron, mercury, lanthanum, molybdenum, rubidium, antimony, scandium, selenium, samarium, tungsten and zinc) have been determined in four male patients during total parenteral nutrition incliding fat emulsion and a special solution for addition of Fe, Zn, manganese, Cu, fluorine and iodine, besides calcium and magnesium, to the infusion solutions. 2. The analyses for trace elements were made with the aid of an ion-exchange technique based on neutron activation, and combined with subsequent gamma spectrometry. 3. The intended intravenous supply of trace elements correspond approximately to the analysed supply. However, all the other trace elements determined were found to be unintentionally administered in small amounts. 4. There was a substantial retention of Fe. Other elements retained were Ag, Co, Cr, Cu, Sb, Sc, and W. 5. Particularly Br and Rb were lost by the patients, but negative balances were also found for As, Au, Cd, Cs, Mo, Se and Zn. However, Zn was retained by one patient with short bowel syndrome. 6. The serum concentrations of thirteen (Ag, Br, Co, Cs, Cu, Fe, Hg, Mo, Rb, Sc, Se, W and Zn) of the trace elements were found to have some decrease during the period of total parenteral nutrition, mostly in accordance with the corresponding balance values, Fe, in particular, was found to have the derectional change in concentration. 7. The administration of trace elements is recommended in long-term total parenteral nutrition.

Adult↗
PubMed1996

Use of a food composition database to estimate daily dietary intake of nutrient or trace elements in Japan, with reference to its limitation.

Daily dietary intake of 28 trace elements (Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Ga, Ge, Li, Mg, Mn, Mo, Ni, Pb, Sb, Sc, Se, Si, Sn, Sr, Ti, Tl, V and Zn) were estimated from the food intake records (collected by the 24-h total food duplicate method), taking advantage of recently published trace element composition tables for foods in Japan. Because the number of food items listed in the tables was not sufficient, the calculation was made with not all foods recorded, and the results should be taken as semi-quantitative. The estimated intake was high (i.e. > 1 mg/day as a median) for Al, Cu, Mg, Mn, Si, Sr and Zn, medium (i.e. 2-985 micrograms/day) for As, B, Ba, Be, Cr, Ge, Mo, Ni, Sb, Sc, Se, Sn and Ti, and low (i.e. < 1 microgram/day) for Cd, Co, Li, Pb and V. Comparison of the present estimates with the reported values in the literature on 15 elements showed that close agreements were observed in the cases of 10 elements (i.e. Al, B, Cr, Cu, Mg, Mn, Mo, Ni, Se and Zn) for which the present estimates are above 1 microgram/day, whereas the discrepancies were significant for four elements (i.e. Cd, Co, Pb and V) with < 1 microgram/day intake. When the expected dietary uptake was compared with that by respiration in the cases of the 16 elements for which the atmospheric concentration data in Japan are available, the uptake was exclusively attributable to the dietary route for all 16 elements with the possible exception of vanadium.

Adult↗
PubMedDate not supplied

Phylogenetic relationships of a class of hominoid-specific retro-elements (SINE-R) on human chromosomes 7 and 17.

SINE-R elements are a class of retroposon derived from the human endogenous retrovirus HERV-K that has been active in hominoid evolution and may include some members that are Homo sapiens specific. Both SINE-R elements and the HERV-K class of element have potential relevance to recent genome change. Here we report on sequences in the SINE-R class that can be detected on human chromosomes 7 and 17 and compare them with sequences that we have previously reported on the X chromosome and in hominoid primates. The retroposons on chromosomes 7 and 17 showed a high degree of sequence homology (88-96%) with other human retroposons (SINE-R.C2, 11, 14, 19, and HS307/HS408). Phylogenetic analysis using the neighbour-joining method revealed that SINE-R-type retroposons on chromosomes 7 and 17 were inter-related with those of hominoid primates, suggesting that various sub-classes of these retroposons have been evolving independently during hominoid evolution. One element (17-11) on chromosome 17 shares one hundred per cent identity with a 7-11 element on chromosome 7 which suggests either recent transposition or a chromosomal translocation. Thus further investigation of the chromosomal locations of SINE-R elements that together with the HERV-K LTR sequence from which they are derived have the capacity to influence the function of neighbouring cellular genes may be expected to clarify the potential role of these elements in recent hominoid evolution.

Animals↗
PubMed2000

Investigation of the transport of trace elements across barriers in humans: studies of placental and mammary transfer.

UNLABELLED: The barrier function of the human mammary gland for selected trace elements was evaluated by analysing 27 maternal sera and corresponding colostrum samples for 14 trace elements. To investigate the impact of the human placenta at the end of gestation on the transfer of 17 trace elements from the mother to the baby, 29 maternal and corresponding umbilical cord sera (UCS) were studied. The uptake of trace elements from the UCS by the fetus was investigated in nine pairs of arterial and venous UCS. In colostrum, the concentration of Cu was 19%, of Se 47%, of Co 80%, of Mg 146%, of Ca 222%, of Sn 228%, of Mn 275%, of Mo 814%, and of Zn 1470% of that of the maternal sera. For Cd and Pb the corresponding values were 200% and 325%, respectively. These data show that the mammary gland can exert an activating as well as an inhibiting effect on the trace element transfer. A concentration gradient mode of action for the transfer of Li, Mo and Sr could be found. In UCS the concentration of Cu was 20%, of Se 55%, of Co 60%, of Sn 85%, of Mo 100%, of Mg 105%, of Ca 120%, of Zn 148%, and of Mn 150% of that of the maternal sera. The corresponding values for Cd were 66% and for Pb 50%. CONCLUSIONS: These findings indicate that the placenta can exhibit an activation or inhibition on transfer as well as a gradient mode of action as for Mo, Cs, Li and Sr. The uptake of essential trace elements from venous UCS by the unborn ranged from 2.5% for Ca to 16.7% for Mo. Both the placenta and the mammary gland can exert an activating, inhibiting or gradient mode of action for selected trace elements, the biological impact of which needs to be further elucidated.

Adult↗
PubMed1980

Elemental content of predigested liquid protein products.

Eight commercially available partially digested gelatin liquid products that have been used as a source of protein in dietary regimens for weight reduction and for protein supplementation were analyzed for their elemental composition. These products were prepared either by dry ashing or wet digestion techniques that were suitable for the analysis of individual elements by their respective analytical methods. Analytical methods used to assess the elemental content included inductively coupled argon plasma emission spectrometry for Ca, Mg, P, Fe, Zn, Cu, Mn, Ni, Mo, V, Be, Co, Cr, Tl, Al, Te, Sn and Sb; atomic absorption spectrophotometry for Na and K; hybride generation with atomic absorption spectrophotometry for Se and As; anodic stripping voltammetry for Cd and Pb; and ion selective electrode for F. The content of almost all of the elements in these products was extremely low compared with the amounts supplied daily for normal individuals by usual sources of dietary protein, the adult United States Recommended Daily Allowances, and typical intakes from the Total Diet Study. The following elements were not detectable in significant amounts in these products by inductively coupled argon plasma emission spectrometry: Mo, V, Be, Co, Cr, Tl, Al, Te, Sn, and Sb. The results suggest that use of these predigested liquid protein products as a sole source of nutriment will result in an inadequate intake of all of the essential elements. These products contained insignificant amounts of Ce and Pb, nonessential toxic elements.

Adult↗
PubMed1998

Trace element supplementation modulates pulmonary infection rates after major burns: a double-blind, placebo-controlled trial.

Infections remain the leading cause of death after major burns. Trace elements are involved in immunity and burn patients suffer acute trace element depletion after injury. In a previous nonrandomized study, trace element supplementation was associated with increased leukocyte counts and shortened hospital stays. This randomized, placebo-controlled trial studied clinical and immune effects of trace element supplements. Twenty patients, aged 40 +/- 16 y (mean +/- SD), burned on 48 +/- 17% of their body surfaces, were studied for 30 d after injury. They consumed either standard trace element intakes plus supplements (40.4 micromol Cu, 2.9 micromol Se, and 406 micromol Zn; group TE) or standard trace element intakes plus placebo (20 micromol Cu, 0.4 micromol Se, and 100 micromol Zn; group C) for 8 d. Demographic data were similar for both groups. Mean plasma copper and zinc concentrations were below normal until days 20 and 15, respectively (NS). Plasma selenium remained normal for group TE but decreased for group C (P < 0.05 on days 1 and 5). Total leukocyte counts tended to be higher in group TE because of higher neutrophil counts. Proliferation to mitogens was depressed compared with healthy control subjects (NS). The number of infections per patient was significantly (P < 0.05) lower in group TE (1.9 +/- 0.9) than in group C (3.1 +/- 1.1) because of fewer pulmonary infections. Early trace element supplementation appears beneficial after major burns; it was associated with a significant decrease in the number of bronchopneumonia infections and with a shorter hospital stay when data were normalized for burn size.

Adult↗
PubMed2003

Transposable elements as tools for genomics and genetics in Drosophila.

The P-element has been the workhorse of Drosophila genetics since it was developed as a tool for transgenesis in 1982; the subsequent development of a variety of systems based on the transposon have provided a range of powerful and flexible tools for genetics and genomics applications. P-element insertions are frequently used as starting-points for generating chromosomal deletions to remove flanking genes, either by screening for imprecise excision events or by selecting for male recombination events. Elements that utilise the yeast FLP/FLP recombination target (FRT) site-specific recombination system have been widely used to generate molecularly marked mitotic clones for mosaic analysis, extending the reach of this powerful genetic tool to virtually all areas of developmental biology. P-elements are still widely used as traditional mutagenesis reagents and form the backbone of projects aimed at generating insertions in every predicted gene in the fly genome. In addition, vectors based on the FLP/FRT system are being used for genome-wide applications, including the development of molecularly-mapped deletion and duplication kits. In addition to these 'traditional' genetic approaches, a variety of engineered elements have been developed for a wide range of transgenic applications, including enhancer trapping, gene-tagging, targeted misexpression, RNA interference (RNAi) delivery and homologous recombination/gene replacement. To complement the use of P-elements, alternative transposon vectors have been developed. The most widely used of these are the lepidopteran element piggyBac and a Drosophila hydei transposon, Minos. In total, a range of transposon vectors offers the Drosophila biologist considerable flexibility and sophistication in manipulating the genome of the fly and has allowed rapid advances in all areas of developmental biology and genome science.

Animals↗
PubMed2004

Synergy of human Pol II core promoter elements revealed by statistical sequence analysis.

MOTIVATION: The subject of our paper is bioinformatics analysis of the distinguishing features of human promoter DNA sequences, in particular of synergetic combinations of core promoter elements therein. We suppose that specific scenarios of transcription initiation are essentially related to various particular implementations of the interaction of basal transcription machinery with promoter DNA, depending on the presence and mutual positioning of core promoter elements. RESULTS: In addition to the combinations of core promoter elements previously experimentally confirmed [TATA box and Initiator (Inr), Downstream Promoter Element (DPE) and Inr, and TFIIB recognition element (BRE) and TATA box] we propose other alternate synergetic combinations: BRE and Inr, BRE and DPE, and TATA and DPE with respective models. The suggestion is based on a high statistical significance of the alternate combinations in promoters, comparable with the significance of the known combinations. We also present arguments that the BRE element is statistically more important than previously thought, and suggest possible mechanisms of action of the core elements in the promoters with multiple transcription start sites. CONTACT: ioschikhes-1@medctr.osu.edu SUPPLEMENTARY INFORMATION: Supplementary information is available at http://bmi.osu.edu/~ilya/synergy/Gershenzon_SuppMat-R.pdf.

DNA Polymerase II↗
PubMed1986

Stable non-mutator stocks of maize have sequences homologous to the Mu1 transposable element.

Mutator stocks of maize produce mutants at many loci at rates 20- to 50-fold above spontaneous levels. Current evidence suggests that this high mutation rate is mediated by an active transposable element system, Mu. Members of this transposable element family are found in approximately 10-60 copies in Mutator stocks. We report here an initial characterization of previously undetected sequences homologous to Mu elements in eight non-Mutator inbred lines and varieties of maize that have a normal low mutation rate. All stocks have approximately 40 copies of sequences homologous only to the terminal repeat and show weak homology to an internal probe. In addition, several of the stocks contain an intact Mu element. One intact Mu element and two terminal-specific clones have been isolated from one non-Mutator line, B37. The cloned sequences have been used to demonstrate that in genomic DNA the intact element, termed Mu1.4B37, is modified, such that restriction sites in its termini are not accessible to cleavage by the HinfI restriction enzyme. This modification is similar to that observed in Mutator lines that have lost activity. We hypothesize that the DNA modification of the Mu-like element may contribute to the lack of Mutator activity in B37.

DNA Restriction Enzymes↗
PubMed1988

Is the Suppressor-mutator element controlled by a basic developmental regulatory mechanism?

We report the results of genetic studies on derivatives of two different alleles of the maize a locus with an insertion of the Suppressor-mutator (Spm) transposable element in which the element is inactive, but can be reactivated readily. We present evidence that the mechanism that determines whether the element is in an active or inactive phase has two genetically distinguishable components. One determines whether or not the element is genetically active (the phase setting) and the other determines the stability of the setting in development, its heritability, and its phase in the next generation (the phase program). We show that the element's phase can be reset in a reproducible pattern during plant development. We also show that the Spm element can be reprogrammed to undergo a subsequent phase change without a concomitant phase change. The capacity to reset and reprogram the Spm element is differentially expressed within the plant in a pattern that is correlated with the developmental fate of apical and lateral meristems, suggesting the involvement of a basic developmental determination mechanism.

Alleles↗
PubMed1989

Modified P elements that mimic the P cytotype in Drosophila melanogaster.

Activity of the P family of transposable elements in Drosophila melanogaster is regulated primarily by a cellular condition known as P cytotype. It has been hypothesized that P cytotype depends on a P element-encoded repressor of transposition and excision. We provide evidence in support of this idea by showing that two modified P elements, each with lesions affecting the fourth transposase exon, mimic most of the P cytotype effects. These elements were identified by means of two sensitive assays capable of detecting repression by a single P element. One assay makes use of cytotype-dependent gene expression of certain P element insertion mutations at the singed bristle locus. The other measures suppression of transposase activity from the unusually stable genomic P element, delta 2-3(99B), that normally produces transposase in both germinal and somatic tissues. The P cytotype-like effects include suppression of snw germline hypermutability, snw somatic mosaicism, pupal lethality, and gonadal dysgenic sterility. Unlike P cytotype, however, there was no reciprocal cross effect in the inheritance of repression.

Alleles↗
PubMed1990

The relationship between P elements and male recombination in Drosophila melanogaster.

P element dysgenesis associated male recombination in Drosophila was examined with a selective system focused upon 5% of the standard female genetic map divided into eight recombination segments. We found no correspondence between P element mobilization events and recombination in males in the intervals monitored. We defined two adjacent short genetic and molecular regions, one devoid of male recombination and the other acting as a "hot spot" for exchange in the absence of supporting P element insertion and excision activity. These data suggest that, even in the presence of mobilizing P elements, transposase may be active at non-P element sites, and that the genome may harbor sequences ranging from highly responsive to completely unresponsive to transposase action. A viewpoint is presented wherein P elements, with sequences that bind transposase, serve to focus the recombination action of transposase to encompass a region of DNA radiating outward from the initial binding site. We suggest that this region is measured in terms of chromosomal segments rather than limited to P element sequences.

Animals↗
PubMed1990

Germ-line and somatic recombination induced by in vitro modified P elements in Drosophila melanogaster.

The P element insertion delta 2-3(99B) has previously been shown to activate incomplete P elements elsewhere in the genome. We show that this element, in conjunction with a second incomplete P element, P[CaSpeR], also induces recombination in the male germ line. The recombination is induced preferentially in the region of the P[CaSpeR] element. Recombinant chromosomes contain the P[CaSpeR] element in more than 50% of cases, and alternative models of transposon replication and preferential chromosome breakage are put forward to explain this finding. As is the case with male recombination induced by P-M dysgenic crosses, recombination appears to be premeiotic in a high proportion of cases. The delta 2-3(99B) element is known to act in somatic cells. Correspondingly, we show that the delta 2-3(99B)-P[CaSpeR] combination elevates the incidence of somatic recombination.

Animals↗