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:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Complementary DNA (cDNA) was prepared with RNA-dependent DNA polymerase from human globin messenger RNA (mRNA). Annealing and translation experimenta with total mRNA from circulating cells from a patient with heterozygous beta/heterozygous beta-delta-o thalassemia (beta-o/delta beta-o-thalassemia) demonstrated no detectable mRNA for beta-globin. cDNA enriched in sequences homologous to beta-globin mRNA was prepared by hydroxylapatite fractionation of hybrids formed between beta-o/delta beta-o-thalassemic mRNA and cDNA made from mRNA from a patient with alpha-thalassemia (hemoglobin H disease). The rate of annealing of this beta-enriched cDNA to normal human nuclear DNA was that of a sequence present as only a single copy per haploid genome. The beta-enriched cDNA annealed to the beta-o-delta beta-o-thalassemia total DNA with approximately the same kinetics as to normal DNA, indicating that no total gene deletion of beta-globin genes from the diploid genome has occurred, although the accuracy of the technique could not exclude with certainty a partial deletion or a deletion of a beta-globin gene from only one of the haploid genomes. This demonstrates that at least one of the beta-o- or the delta beta-o-thalassemia haploid genomes in this case contains a substantially intact beta-globin gene.
...
PMID:Human globin gene analysis for a patient with beta-o/delta beta-thalassemia. 4 57

Complementary DNA enriched in sequences hybridizing to beta-globin mRNA was prepared with viral RNA-dependent DNA polymerase and used as a probe for the presence of beta-globin mRNA in nuclear and cytoplasmic RNA from two Italian patients with beta0-thalassaemia. In both cases the beta-globin gene was present and cytoplasmic mRNAbeta was absent; however, one case appeared to transcribe mRNAbeta and to fail to process it, while the other appeared transcriptionally defective. Evidence is also presented that the low levels of hybridization usually found at high RNA/cDNAbeta ratios in beta0-thalassaemia are due to delta-globin mRNA; the melting profile of the hybrid formed has been determined and a low melting temperature relative to mRNAbeta - cDNAbeta demonstrated.
...
PMID:Transcriptional and post-transcriptional defects in beta0-thalassaemia. 92 69

The specificity of hybridization was compared between the human and rabbit alpha and beta-globin complementary DNAs (cDNAs) and the corresponding alpha and beta-globin messenger RNAs (mRNAs). The globin chain-specific mRNAs of rabbit were prepared from polysomes incubated with O-methylthreonine (alpha and beta) or from postribosomal supernatant (alpha). Enrichment for either the alpha- or beta-globin mRNA was demonstrated by cell-free protein synthesis and by RNA-cDNA hybridization. Human mRNAs, active as templates for RNA-directed DNA polymerase, were prepared from reticulocytes of patients with hemolytic anemia, alpha-thalassemia (hemoglobin H disease), and beta-thalassemia. Because there was partial cross-hybridization between human mRNA and rabbit cDNA, the rabbit alpha- and beta-globin cDNAs could be used to demonstrate that the beta-thalassemia mRNA was enriched in human alpha-globin mRNA sequences and that the alpha-thalassemia mRNA was enriched in human beta-globin mRNA sequences. These results were confirmed by preparation of thalassemia globin cDNAs and subsequent hybridization to their template mRNAs. The amount of cross-hybridization between the human and rabbit alpha-globin mRNA and the two alpha-globin cDNAs was comparable to the cross-hybridization between the two beta-globin mRNAs and the two beta-globin cDNAs, indicating a similar degree of evolutionary divergence in the nucleotide sequences of the two globin genes.
...
PMID:alpha-and beta-Globin complementary deoxyribonucleic acids of human and rabbit. Specificity of hybridization. 112 37

We have previously demonstrated that DNA can be extracted from the dried blood specimen of the type used for newborn screening. The technique presented here allows us to extract RNA from newborn screening specimens for cDNA synthesis by reverse transcriptase and amplification by the polymerase chain reaction (PCR). Products of the PCR reaction are then analyzed by restriction enzymes. This method successfully distinguishes beta A and beta S transcripts in unaffected (AA), carrier (AS), and affected (SS) individuals. The value of this approach for identification of a compound heterozygous patient with S/beta-thalassemia, using the original newborn screening specimen, is also demonstrated. This work shows that mRNA is stable in dried blood specimens and that analysis of the mRNA phenotype can be a useful adjunct in the application of molecular genetic technology to newborn screening.
...
PMID:RNA analysis from newborn screening dried blood specimens. 135 Oct 35

The haploid nucleus of a human cell contains 3 X 10(9) base pairs. Organized in linear duplex, this DNA would stretch out to a length of some 90 cm. Thus, organization of chromosomes has been a major subject for pioneer cytogenetists. Long lasting controversies on the strandedness of chromosomes, together with newly developed banding techniques, led us to molecular cytogenetics. Next, the discovery of reverse transcriptase, restriction endonucleases, and other recombinant DNA methods have enabled us to isolate and characterize genes from any organism and to determine the DNA sequences and any encoded protein sequences. These new technologies have already helped us to understand many inherited diseases at a molecular level. In sickle cell anemia, thalassemia and in other mendelian disorders we can know their molecular defects by examining the DNA from peripheral leukocytes, without the need for complex biochemical assays or biopsies. Southern blot analysis using restriction endonuclease and a probe is a basic tool for molecular diagnosis. cDNA or DNA fragments are used as probes. Recently, synthesized oligonucleotide probes are available, if the DNA sequence of a gene is determined. In addition, restriction fragment length polymorphisms (RFLPs), play a very important role in the molecular diagnosis. Linkage analysis using RFLPs linked to the gene locus of a certain disease also permits the detection of the patients and carriers within families with genetic diseases of unknown cause. Starting with the genetic map and physical map, genes for cystic fibrosis and Duchenne muscular dystrophy have recently been isolated and cloned.
...
PMID:[Recent advances in human molecular genetics]. 197 24

A hybridization assay procedure was devised that makes possible quantitation of the ratio of mRNA of alpha to mRNA of beta globin chains in an RNA sample. The assay uses the radioactive synthetic DNA copies obtained by incubation of RNA-dependent DNA polymerase of avian myeloblastosis virus with rabbit globin mRNA that is 80-90% enriched in mRNA specific for synthesis of alpha or beta globin chains. The rabbit alpha-chain mRNA is obtained from the postribosomal supernatant of rabbit reticulocyte lysates; the rabbit beta-chain mRNA is obtained from the largest polysomes of rabbit reticulocytes treated with L-O-methylthreonine. Sufficient homology exists between rabbit and human globin chains and globin mRNAs that the synthetic DNA copies of chain-specific rabbit globin mRNA hybridize with human globin mRNA. Applied to the study of globin mRNA isolated from reticulocytes of humans with alpha and beta thalassemia, the technique revealed marked quantitative deficiency of alpha-chain mRNA relative to beta-chain mRNA in alpha thalassemia and similar deficiency of beta-chain mRNA relative to alpha-chain mRNA in beta thalassemia. The thalassemia syndromes are therefore characterized by true quantitative deficiency of the mRNA specific for the affected globin chain.
...
PMID:Quantitative deficiency of chain-specific globin messenger ribonucleic acids in the thalassemia syndromes. 412 5

In previous studies of patients with beta thalassemia, mRNA extracted from reticulocytes in peripheral blood when added to cell-free systems reproduces the deficient beta-chain synthesis characteristic of intact cells. The present studies with specific probes for alpha and beta mRNA were designed to decide whether the decreased beta mRNA activity is due to the presence of abnormal or reduced beta globin mRNA in these cells. Purified alpha and beta complementary DNAs (cDNAs) have been synthesized with RNA-instructed DNA polymerase; alpha and beta mRNAs isolated from heavy (beta-producing) and light (alpha-producing) polyribosomes of rabbit reticulocytes were used as templates. Each of the cDNAs is more than 80% pure by the criterion of biological activity. The alpha cDNA labeled with [(32)P]dCTP and the beta cDNA labeled with [(3)H]dCTP have been added simultaneously to reaction mixtures containing various concentrations of mRNA from thalassemic and nonthalassemic subjects. The extent and rate of hybridization were determined, permitting a comparison of relative alpha and beta mRNA content in the same annealing mixture. In six nonthalassemic patients, relatively equal amounts of hybridizable alpha and beta mRNA appear to be present. In five of seven patients with beta-thalassemia, significantly decreased amounts of beta mRNA compared to alpha mRNA can be demonstrated. In two patients with Hemoglobin H disease, there is a decreased amount of alpha mRNA compared to beta mRNA.
...
PMID:Decreased globin messenger RNA in thalassemia detected by molecular hybridization. 412 7

Effective gene therapy for the severe hemoglobin (Hb) disorders, sickle-cell anemia and thalassemia, will require an efficient method to transfer, integrate, and express a globin gene in primary erythroid cells. To evaluate recombinant adeno-associated virus (rAAV) for this purpose, we constructed a rAAV vector encoding a human gamma-globin gene (pJM24/vHS432A gamma). Its 4725-nucleotide genome consists of two 180-bp AAV inverted terminal repeats flanking the core elements of hypersensitive sites 2, 3, and 4 from the locus control region of the beta-globin gene cluster, linked to a mutationally marked A gamma-globin gene (A gamma) containing native promoter and RNA processing signals. CD34+ human hematopoietic cells were exposed to rAAV particles at a multiplicity of infection of 500-1000 and cultured in semisolid medium containing several cytokines. A reverse transcriptase polymerase chain reaction assay distinguished mRNA signals derived from transduced and endogenous human gamma-globin genes. Twenty to 40% of human erythroid burst-forming unit-derived colonies expressed the rAAV-transduced A gamma-globin gene at levels 4-71% that of the endogenous gamma-globin genes. The HbF content of pooled control colonies was 26%, whereas HbF was 40% of the total in pooled colonies derived from rAAV transduced progenitors. These data establish that rAAV containing elements from the locus control region linked to a gamma-globin gene are capable of transferring and expressing that gene in primary human hematopoietic cells resulting in a substantial increase in HbF content.
...
PMID:Recombinant adeno-associated virus (rAAV)-mediated expression of a human gamma-globin gene in human progenitor-derived erythroid cells. 752 85

We present in vivo evidence that there is no reduction in beta-mRNA accumulation in patients with nonsense codons in the terminal exon of the beta-globin gene. Using reverse transcriptase/polymerase chain reaction (RT-PCR), beta-globin cDNA was isolated from the reticulocytes of individuals heterozygous for nonsense codon mutations in exons II and III of the beta-globin gene. Clinically asymptomatic individuals heterozygous for mutations causing premature termination of translation in exon II [beta(0)39(C-T) and F/S71/72(+A)] were found to have almost no mutant beta-cDNA, whereas patients with nonsense codon mutations in exon III [beta 121(G-T) and beta 127(C-T)] with the clinical phenotype of thalassemia intermedia had comparable levels of mutant and normal beta-cDNA. Translation of the mutant beta-mRNA from patients with nonsense codon mutations in exon III would give rise to truncated beta-globin chains, which could explain the more severe phenotype seen in these individuals.
...
PMID:Nonsense codon mutations in the terminal exon of the beta-globin gene are not associated with a reduction in beta-mRNA accumulation: a mechanism for the phenotype of dominant beta-thalassemia. 816 74

We are interested in the genetic mechanisms whereby several classes of drugs increase fetal hemoglobin (HbF) in patients with sickle-cell anemia or beta-thalassemia. Recently, we have shown (Kollia et al., Proc. Natl. Acad. Sci. U.S.A. 93: 5693, 1996) that cultured primary human adult erythroid cells (hAEC) offer a useful model for the study of transcriptional and posttranscriptional regulation of globin gene expression. We have found also that hemin markedly increases HbF levels in these cells. We report here the effect of hemin on globin gene transcription and RNA processing in hAEC. Quantitative reverse transcriptase-polymerase chain reaction analysis showed that the gamma-globin message levels in the cytoplasm and nucleus were increased two-fold by hemin. In the untreated cells, only spliced gamma-transcripts were detected in the cytoplasm, indicating that only completely processed gamma-RNA is transported to the cytoplasm, whereas approximately half of the nuclear gamma-globin RNA transcripts were unspliced. After treatment with hemin, correctly spliced gamma-transcripts increased in the cytoplasm and nucleus, while the unprocessed gamma-transcripts decreased in number in the nucleus. We also studied epsilon-globin RNA transcripts; in the cytoplasm of untreated cells, only correctly processed transcripts were present, whereas the nuclear epsilon-globin RNA transcripts were unspliced. In hemin-induced cells, unspliced nuclear epsilon-transcripts decreased in number. In contrast to the gamma- and epsilon-globin genes, the levels of full-length, correctly spliced beta-globin message are not affected by hemin. Nuclear run-on transcription assays confirmed the increase in the rate of transcription of gamma- and epsilon-globin genes in hemin-treated versus untreated hAEC. These results indicate that hemin affects the expression of embryonic and fetal globin genes by acting both at the transcriptional and posttranscriptional levels. These results may be relevant to the action of other agents that affect the hemoglobin phenotype of human erythroid cells.
...
PMID:Modulation of globin gene expression in cultured erythroid precursors derived from normal individuals: transcriptional and posttranscriptional regulation by hemin. 922 May 39


1 2 Next >>

---