Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
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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.
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PMID:Decreased globin messenger RNA in thalassemia detected by molecular hybridization. 412 7

Gliomas are a heterogeneous group of tumors with evolving classification based on genotype. Isocitrate dehydrogenase (IDH) mutation is an early event in the formation of some diffuse gliomas, and is the best understood mechanism of their epigenetic dysregulation. Glioblastoma may evolve from lower-grade lesions with IDH mutations, or arise independently from copy number changes in platelet-derived growth factor receptor alpha (PDGFRA) and phosphatase and tensin homolog (PTEN). Several molecular subtypes of glioblastoma arise from a common proneural precursor with a tendency toward transition to a mesenchymal subtype. Following oncogenic transformation, gliomas escape growth arrest through a distinct step of aberrant telomere reverse transcriptase (TERT) expression, or mutations in either alpha thalassemia/mental retardation syndrome (ATRX) or death-domain associated protein (DAXX) genes. Metabolic reprogramming allows gliomas to thrive in harsh microenvironments such as hypoxia, acidity, and nutrient depletion, which contribute to tumor initiation, maintenance, and treatment resistance.
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PMID:Brain Tumors of Glial Origin. 3176 Jun 51