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:2.7.7.6 (RNA polymerase)
34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is unclear whether the core promoter is involved in developmental regulation. To address this question, we mutated the TATA box of the human gamma-globin gene, produced transgenic mice, and examined the effect of the mutation during the course of mouse development. In our test system, the gamma-globin gene is expressed at similar levels in the embryonic and adult erythroid cells. The TATA box mutation dramatically reduced expression of the gamma-globin gene in the adult but not in embryonic erythroid cells. In addition, the disruption of the gamma TATA box significantly reduced the recruitment of TATA box-binding protein (TBP) in the adult cells, but not in embryonic cells, suggesting that the recruitment of TBP to the gamma gene promoter is developmentally specific. Similarly, the recruitment of transcription factor II B and RNA polymerase II to the gamma promoter was affected in the adult but not in embryonic cells. The distinct effects of the TATA mutation in the embryonic and adult developmental stages suggest that the basal transcription apparatus can be recruited to a core promoter in a developmental stage-dependent manner. The TATA mutation resulted in a shift of transcription initiation site 6 bp or longer upstream to the cap site both in the embryonic and adult erythrocytes. We conclude that the TATA box determines the initiation site but not the efficiency of transcription of the gamma-globin gene.
...
PMID:Developmental specificity of recruitment of TBP to the TATA box of the human gamma-globin gene. 1196 8

The classification of chronic neutrophilic leukemia (CNL) is controversial. Our purpose was to correlate clinical, pathologic, and molecular analyses in 2 cases of CNL. In both cases, the patients were referred because of a substantially increased peripheral WBC count noted during routine examination. Bone marrow biopsies and aspirate smears revealed hypercellularity with myeloid/erythroid ratios of 4:1 and 11:1, respectively. The bone marrow aspirate results were as follows: case 1: blasts, 2%; promyelocytes, 2%; myelocytes, 6%; metamyelocytes, 16%; band neutrophils, 13%; segmented neutrophils, 34%; and case 2: blasts, 1%; promyelocytes, 2%; myelocytes, 15%; metamyelocytes, 20%; band neutrophils, 24%; neutrophils, 19%. Reverse transcriptase in situ polymerase chain reaction studies demonstrated expression of mu-BCR-ABL transcripts in 13% and 25% of the bone marrow cells, respectively. In both cases, the positive signal was noted mainly in the early granulocytic precursors and was present in occasional mature neutrophils. To our knowledge, this is thefirst in situ demonstration of mu-BCR-ABL expression in CNL Ourfindings reinforce the usefulness of this messenger RNA as a molecular marker of CNL.
...
PMID:Expression of mu-BCR-ADL transcripts in chronic neutrophilic leukemia. 1247 76

To investigate the molecular basis of beta-globin gene activation, we analyzed factor recruitment and histone modification at the adult beta-globin gene in wild-type (WT)/locus control region knockout (DeltaLCR) heterozygous mice and in murine erythroleukemia (MEL) cells. Although histone acetylation and methylation (Lys 4) are high before and after MEL differentiation, recruitment of the erythroid-specific activator NF-E2 to the promoter and preinitiation complex (PIC) assembly occur only after differentiation. We reported previously that targeted deletion of the LCR reduces beta-globin gene expression to 1%-4% of WT without affecting promoter histone acetylation. Here, we report that NF-E2 is recruited equally efficiently to the adult beta-globin promoters of the DeltaLCR and WT alleles. Moreover, the LCR deletion reduces PIC assembly only twofold, but has a dramatic effect on Ser 5 phosphorylation of RNA polymerase II and transcriptional elongation. Our results suggest at least three distinct stages in beta-globin gene activation: (1) an LCR-independent chromatin opening stage prior to NF-E2 recruitment to the promoter and PIC assembly; (2) an intermediate stage in which NF-E2 binding (LCR-independent) and PIC assembly (partially LCR-dependent) occur; and (3) an LCR-dependent fully active stage characterized by efficient pol II elongation. Thus, in its native location the LCR functions primarily downstream of activator recruitment and PIC assembly.
...
PMID:The beta -globin locus control region (LCR) functions primarily by enhancing the transition from transcription initiation to elongation. 1267 91

The developmentally regulated mammalian beta-globin genes are activated by a distant locus control region/enhancer. To understand the role of chromatin remodeling complexes in this activation, we used stably replicated chromatin templates, in which transcription activation of the human embryonic epsilon-globin gene depends on the tandem Maf-recognition elements (MAREs) within the beta-globin locus control region HS2 enhancer, to which the erythroid factor NF-E2 binds. The HS2 MAREs are required for nucleosome mobilization and histone hyperacetylation at the distant promoter. Nucleosome mobilization also requires the promoter TATA box, and is independent of histone hyperacetylation. In contrast, promoter hyperacetylation requires the promoter GATA-1, and CACC-factor activator motifs, as well as the TATA box. ChIP analysis reveals that NF-E2 is associated with the active epsilon-globin promoter, which lacks an NF-E2 binding sequence, in a TATA box and HS2/MARE-dependent fashion. NF-E2 association with the epsilon-globin promoter coincides with that of RNA polymerase II at both regulatory sites. The results emphasize MARE-TATA box interactions in the recruitment of complexes modifying promoter chromatin for transcription activation and imply close physical interaction between widely separated regulatory sequences mediated through these sites.
...
PMID:A major role for the TATA box in recruitment of chromatin modifying complexes to a globin gene promoter. 1277 26

High-level alpha-globin expression depends on cis-acting regulatory sequences located far upstream of the alpha-globin cluster. Sequences that contain the alpha-globin positive regulatory element (PRE) activate alpha-globin expression in transgenic mice. The alpha-globin PRE contains a pair of composite binding sites for the transcription factors activating protein 1 and nuclear factor erythroid 2 (AP1/NFE2). To determine the role of these binding sites in alpha-globin gene transcription, we mutated the AP1/NFE2 sites in the alpha-globin PRE in mice. We replaced the AP1/NFE2 sites with a neomycin resistance gene (neo) that is flanked by LoxP sites (floxed). Mice with this mutation exhibited increased embryonic death and alpha-thalassemia intermedia. Next, we removed the neo gene by Cre-mediated recombination, leaving a single LoxP site in place of the AP1/NFE2 sites. These mice were phenotypically normal. However, alpha-globin expression, measured by allele-specific RNA polymerase chain reaction (PCR), was decreased 25%. We examined the role of the hematopoietic-restricted transcription factor p45Nfe2 in activating expression through these sites and found that it is not required. Thus, we have demonstrated that AP1/NFE2 binding sites in the murine alpha-globin PRE contribute to long-range alpha-globin gene activation. The proteins that mediate this effect remain to be determined.
...
PMID:Role of AP1/NFE2 binding sites in endogenous alpha-globin gene transcription. 1292 35

Efficient transcription of genes requires a high local concentration of the relevant trans-acting factors. Nuclear compartmentalization can provide an effective means to locally increase the concentration of rapidly moving trans-acting factors; this may be achieved by spatial clustering of chromatin-associated binding sites for such factors. Here we analyze the structure of an erythroid-specific spatial cluster of cis-regulatory elements and active beta-globin genes, the active chromatin hub (ACH; ref. 6), at different stages of development and in erythroid progenitors. We show, in mice and humans, that a core ACH is developmentally conserved and consists of the hypersensitive sites (HS1-HS6) of the locus control region (LCR), the upstream 5' HS-60/-62 and downstream 3' HS1. Globin genes switch their interaction with this cluster during development, correlating with the switch in their transcriptional activity. In mouse erythroid progenitors that are committed to but do not yet express beta-globin, only the interactions between 5' HS-60/-62, 3' HS1 and hypersensitive sites at the 5' side of the LCR are stably present. After induction of differentiation, these sites cluster with the rest of the LCR and the gene that is activated. We conclude that during erythroid differentiation, cis-regulatory DNA elements create a developmentally conserved nuclear compartment dedicated to RNA polymerase II transcription of beta-globin genes.
...
PMID:The beta-globin nuclear compartment in development and erythroid differentiation. 1451 43

Fibronectin in general is involved in adhesion and maturation of the erythroid lineage, in megakaryopoiesis and in the differentiation of human multipotent hematopoietic progenitor cells. However, little information exists about the expression of the oncofetal fibronectin isoform containing the ED-B domain (ED-B+ fn) in adult human hematopoiesis. The study was aimed to analyze the ED-B+ fn expression in normal human bone marrow cells by immunocytochemistry, flow cytometry and reverse-transcriptase polymerase chain reaction. The in vivo results were compared to ED-B+ fn expression in human long-term bone marrow cultures (LTBMC), cytokine supported expansion cultures of CD34+ peripheral blood progenitor cells (PBPC) and in leukemic cell lines with megakaryocytic characteristics (K562, CMK). ED-B+ fn protein was immunocytochemically demonstrated in normal bone marrow megakaryocytes as well as in megakaryocytic progenitor/precursor cells generated ex vivo from PBPC but we failed to detect ED-B+ fn mRNA. It was strongly expressed in LTBMC (RNA and protein). Analysis of human bone marrow mononuclear cells by flow cytometry and confocal microscopy revealed only cytoplasmic ED-B+ fn. The SCF/TPO induced megakaryocytic differentiation of ED-B+ fn negative CMK cells is associated with an increase of large megakaryocytes followed by an intracellular accumulation of ED-B+ fn mRNA and protein. We conclude that in normal human hematopoiesis ED-B+ fn protein expression and intracellular accumulation is restricted to differentiation of megakaryocytes. Low-abundant synthesis, intracellular accumulation and failure of membrane exposure might be due to a function during early events of wound healing (formation of a platelet-rich provisional extracellular matrix).
...
PMID:Differential in vivo and in vitro expression of ED-B+ fibronectin in adult human hematopoiesis. 1461 53

The CCAAT box is a widespread motif in eukaryotic promoters. In this study we demonstrate that the effects of the CCAAT box on gamma-globin gene activation are developmentally distinct. Although this promoter element is essential for high level gamma gene expression in adult erythropoiesis, it plays little role in embryonic erythroid cells. The CCAAT mutation in the human gamma-globin gene promoter impairs recruitment of TATA-binding protein (TBP), TFIIB, and RNA polymerase II in adult splenic erythroblasts but not in embryonic erythroid cells. We also show that the efficiency of gamma gene transcription is correlated with recruitment of TBP on the TATA box but that the level of TBP recruitment is not nuclear factor Y (NF-Y)-dependent. Our data also suggest that it is unlikely that transcriptional stimulation by the CCAAT box is exerted through direct protein-protein interaction between NF-Y and TBP.
...
PMID:Developmentally specific role of the CCAAT box in regulation of human gamma-globin gene expression. 1464 37

The mammalian beta-globin loci each contain a family of developmentally expressed genes, and a far upstream regulatory element, the locus control region (LCR). In adult murine erythroid cells, the LCR and the transcribed beta-globin genes exist within domains of histone acetylation and RNA polymerase II (pol II) is associated with them. In contrast, the silent embryonic genes lie between these domains within hypoacetylated chromatin, and pol II is not found there. We used chromatin immunoprecipitation and real-time PCR to analyze histone modification and pol II recruitment to the globin locus in human erythroid K562 cells that express the embryonic epsilon-globin gene but not the adult beta-globin gene. H3 and H4 acetylation and H3 K4 methylation were continuous over a 17-kb region including the LCR and the active epsilon-globin gene. The level of modification varied directly with the transcription of the epsilon-globin gene. In contrast, this region in nonerythroid HeLa cells lacked these modifications and displayed instead widespread H3 K9 methylation. pol II was also detected continuously from the LCR to the epsilon-globin gene. These studies reveal several aspects of chromatin structure and pol II distribution that distinguish the globin locus at embryonic and adult stages and suggest that both enhancer looping and tracking mechanisms may contribute to LCR-promoter communication at different developmental stages.
...
PMID:Developmental stage differences in chromatin subdomains of the beta-globin locus. 1510 44

Analysis of cell-free fetal DNA (fDNA) and RNA in maternal plasma could be useful in the diagnosis and management of complications of pregnancy. In this review, we discuss our studies to investigate the potential of fetal nucleic acid measurement in maternal plasma as a marker of fetomaternal hemorrhage (FMH) after elective first-trimester termination of pregnancy (TOP). Using quantitative real-time PCR amplification of the DYS1 sequence, elevation of plasma fDNA levels after TOP was observed, especially in the late first trimester. This corresponds with the functional development of the placental vascular structure and fetal hematopoiesis. This Y sequence-based PCR amplification assay, however, limits the analysis to pregnant women carrying male fetuses. Therefore, we also developed a real-time quantitative reverse-transcriptase PCR assay of the gamma-globin transcript as a marker of fetal erythroid cells. Although plasma gamma-globin mRNA levels were decreased after TOP in many patients, an elevation was observed in some patients at greater than 9 weeks' gestation, which is consistent with the increase in plasma fDNA levels. Our data suggest that fetal hematopoietic cells contribute to the pool of fetal nucleic acids in the maternal circulation. Measurement of cell-free fetal nucleic acid levels in maternal plasma may have clinical application as a novel marker of FMH after 9 weeks of gestation.
...
PMID:Circulating cell-free fetal nucleic acid analysis may be a novel marker of fetomaternal hemorrhage after elective first-trimester termination of pregnancy. 1525 51


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---