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

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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)

Bovine thyroglobulin 33-S mRNA has been used as a template for the synthesis of a complementary DNA, using RNA-directed DNA polymerase from the avian myeloblastosis virus. The yield of the reaction was relatively poor and the size of the cDNA did not exceed 10 S. Nevertheless, a copy of high specific radioactivity (approximately 10(7) counts. min-1 microgram-1) could be obtained which hybridized specifically back to its template with an rot1/2 value about 5 times higher than that observed in hybridizations between hemoglobin mRNA (alpha + beta chain) and hemoglobin cDNA. This suggests that thyroglobulin mRNA does not contain extensive internal repetitive sequences. Quantification of thyroglobulin mRNA sequences among various RNA preparations from the beef thyroid was performed using cDNA/RNA hybridizations in RNA excess. The results confirmed that thyroglobulin mRNA represents the large majority of mRNA in membrane-bound polysomes and indicated the virtual absence of thyroglobulin sequences on free polyosomes. The cDNA transcribed from mRNA of bovine origin hybridized efficiently with thyroid RNA from goats, dogs and humans. Although the heterologuous hybrids exhibited the expected decrease in thermal stability, the bovine cDNA provides an appropriate probe for studies dealing with the expression of the thyroglobulin gene in various mammals including man.
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PMID:Reverse transcription of thyroglobulin 33-S mRNA. 7 91

A highly purified thyroglobulin mRNA was isolated from human nodal euthyroid goiter. A full-length cDNA was synthesized from 33S RNA by using reverse transcriptase in the presence of human placenta ribonuclease inhibitor. A DNA complementary to human Tg mRNA was used in liquid hybridization experiments to quantify Tg mRNA. The amount of Tg mRNA in euthyroid nodal and congenital goiter was reduced. In thyroid cancer Tg specific mRNA was absent. Direct correlation between Tg gene expression in thyroid cells and DNAase-I hypersensitivity of chromatin from the thyroid gland nucleus was revealed.
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PMID:[Changes in the chromatin structure of the thyroid cells related to the expression of the thyroglobulin gene]. 197 92

A highly purified thyroglobulin (Tg) mRNA was isolated from human nodal euthyroid goiter. Ultracentrifugation in a 5-20% sucrose density gradient revealed that the protein has a sedimentation coefficient of 33S. cDNA was synthesized from the 33S RNA, using reverse transcriptase in the presence of a human placental ribonuclease inhibitor. In order to detect the polymorphism of restriction fragment length, screening of high molecular weight DNA from normal human thyroid gland and from nodal euthyroid and diffuse toxic goiters was carried out, using Tg cDNA probes and plasmid DNA containing a Tg cDNA fragment. After restriction with endonuclease Hind III, three Tg-containing fragments were identified both in the normal and nodal euthyroid goiters, whereas restriction with endonuclease Bam HI revealed two Tg-containing fragments in nodal euthyroid and diffuse toxic goiters.
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PMID:[Mapping of the thyroglobulin gene in high molecular weight DNA from the human thyroid in normal conditions and in thyroid pathology]. 256 30

Highly purified thyroglobulin mRNA was isolated from human nodal euthyroid goiter. Full length cDNA was synthesized from 33S RNA by using reverse transcriptase in the presence of human placenta ribonuclease inhibitor. DNA complementary to human Tg mRNA was used in liquid hybridization experiments to determine the quantity of Tg mRNA. The amount of Tg mRNA in euthyroid nodal and congenital goiter was reduced. Tg specific mRNA was absent in thyroid cancer cells.
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PMID:[Thyroglobulin gene expression in human thyroid cells in various types of thyroid pathology]. 258 2

Human thyroglobulin mRNA was isolated from Graves' goitres by size selection of total poly(A)-rich RNA in a sucrose gradient. It sedimented at 33 S, as in other mammalian species, and showed a single component of approximately 8500 bases by gel electrophoresis. cDNA was synthesized from the 33-S RNA by using reverse transcriptase in the presence of human placenta ribonuclease inhibitor and in conditions allowing the formation of long transcripts. The latter was made double-stranded using reverse transcriptase and blunt-ended with nuclease S1. After tailing with dCTP and terminal transferase, the double-stranded cDNA was annealed to pBR322 DNA that had been cleaved at the endonuclease PstI site and tailed with dGTP. The resulting plasmids were used to transform Escherichia coli C600 cells and four cloned recombinants were selected. Each plasmid DNA was shown to contain a sequence complementary to human thyroglobulin mRNA by hybridization with a labeled 33-S mRNA, visualization of cDNA . mRNA hybrids by electron microscopy and filter hybridization selection of mRNA directing the synthesis of immunologically related thyroglobulin peptides in the reticulocyte lysate. The four inserted DNA sequences were 1400 - 1800 base pairs long, two of them showing an homologous sequence of 1100 base pairs. Together, the four cloned DNA fragments represented 63% of the 8500 bases of human thyroglobulin mRNA.
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PMID:Cloning of four DNA fragments complementary to human thyroglobulin messenger RNA. 617 25

The thyroid gland is a highly vascular tissue, and its blood flow changes dramatically in various pathological conditions. Although the mechanisms regulating these changes in vascularity and blood flow are not well understood, candidate mediators include endothelin-1 (ET-1) and nitric oxide (NO). In the present study, we used a reverse transcriptase-polymerase chain reaction assay to determine which components of these vasoregulatory pathways are present in the thyroid and to analyze changes in gene expression in an experimental model of goiter formation and involution. Expression of messenger RNAs (mRNAs) encoding ET-1, ET receptors (ETA and ETB), ET-converting enzyme, and the three nitric oxide synthase (NOS) isoforms (NOS I, NOS II, and NOS III) was readily detected in the rat thyroid. After goiter formation was induced by thiouracil and a low iodine diet, there was increased expression of the genes encoding ET-related proteins (ET-1, 3.2-fold; ETA, 2.9-fold; ETB, 3.5-fold) as well as two of the three NOS isoforms (NOS I, 2.7-fold; NOS III, 4.9-fold). During iodide-induced involution, the ET-related mRNA levels remained elevated, whereas those of the two NOS isoforms returned to basal values. ET-converting enzyme, NOS II, and thyroglobulin mRNAs were minimally affected in this model, providing evidence for selective regulation of these genes. To assess whether NO plays a role in vascular changes during goiter formation, animals were treated with a NOS inhibitor, N-nitro-L-arginine methyl ester (NAME). NOS activity in the thyroid was inhibited by more than 75% after treatment with NAME. Thyroid hormone and TSH levels were unchanged. Although NAME had little effect on overall thyroid size, vascular expansion during goiter formation was decreased by 36%. We conclude that the thyroid gland expresses a complex network of vasoactive genes whose expression is regulated dynamically during thyroid goiter formation and involution. NO production and probably other locally produced vasoactive substances are involved in changes in thyroid vascularization.
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PMID:Expression of nitric oxide synthase isoforms in the thyroid gland: evidence for a role of nitric oxide in vascular control during goiter formation. 758 72

TTF-1 and Pax-8 are thyroid-specific transcription factors, from homeo and paired box genes, respectively, that are responsible for thyroid development and for thyroglobulin and thyroperoxidase gene expression. However, TTF-1 and Pax-8 preferentially bind to the thyroglobulin and thyroperoxidase promoters, respectively. Here, we have studied a patient with defective thyroglobulin synthesis. Thyroglobulin mRNA was found at very low levels while the mRNA for thyroperoxidase was found to be more abundant compared with control tissue. The low levels of thyroglobulin mRNA are caused by a transcriptional defect due to the virtual absence of TTF-1 expression as determined by Northern blot analysis, reverse transcriptase-PCR, and electrophoretic mobility shift assays. The level of Pax-8 mRNA was the same in the goiter and in the control thyroid. These results are the first reported evidence of a congenital goiter with a thyroglobulin synthesis defect due to the low expression of the thyroid-specific transcription factor TTF-1. Moreover, these data suggest that TTF-1 and Pax-8 would be differentially regulating thyroglobulin and thyroperoxidase gene transcription.
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PMID:Congenital human thyroglobulin defect due to low expression of the thyroid-specific transcription factor TTF-1. 763 72

A recent report has identified a new autoantigen called D1 that appears to be associated with Graves' ophthalmopathy and is expressed in the thyroid and eye muscle. To better characterize the tissue specificity and disease relevance of this antigen, we evaluated the expression of D1 RNA in various human tissues using a reverse transcriptase polymerase chain reaction assay. These studies indicate a wide tissue distribution of the messenger RNA for this antigen, including the thyroid, eye muscle, parathyroid, spleen, skeletal muscle, and uterus. There were variations in the relative amounts of specific message for D1 in the different tissues, with the uterus, thyroid, and eye muscle having the greatest amount of product per microgram of total RNA. A maltose binding protein-D1 fusion protein was expressed in Escherichia coli, purified, and used to assess serologic reactivity to D1 by Western blot. Autoantibodies to this antigen were noted in 19 of 24 (78%) of Hashimoto's disease patients, 26 of 41 (63%) of Graves' disease patients, and in 9 of 17 (53%) of normal controls. Sixty percent of Graves' disease patients with clinical ophthalmopathy had antibodies to D1, as did 63% of Graves' patients without signs or symptoms of clinical ophthalmopathy. There was no correlation between reactivity to D1 and either clinical measures of hyperthyroidism or antibody titers to thyroid peroxidase or thyroglobulin. The presence of autoantibodies to this antigen in patients with Hashimoto's disease, in Graves' disease patients without ophthalmopathy and in normal controls indicate that serologic recognition of this antigen is not restricted to patients with ophthalmopathy. In addition, the expression of messenger RNA for this antigen in multiple types of cells questions the tissue specificity of this autoantigen.
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PMID:Tissue specificity and serologic reactivity of an autoantigen associated with autoimmune thyroid disease. 834 48

Thyroglobulin is used to induce in mice experimental autoimmune thyroiditis (EAT), a model for Hashimoto thyroiditis. Because murine thyroglobulin is a more potent inducer of EAT than heterologous thyroglobulins, it has been hypothesized that it contains unique pathogenic epitopes. The validation of this hypothesis has been hampered by the lack of the murine thyroglobulin sequence. To identify murine-specific areas in thyroglobulin, we cloned, by reverse transcriptase PCR, and sequenced the complete murine thyroglobulin cDNA. This encodes a polypeptide of 2748 amino acids that is 73.5 and 71.8% identical to bovine and human thyroglobulin, respectively. Six regions are unique to each species. We also analyzed through EpiMer the sequences able to bind to the I-Ek major histocompatibility allele and, therefore, function as T cell epitopes. EpiMer analysis showed seven murine-specific T cell epitopes in thyroglobulin. The availability of the complete murine thyroglobulin sequence should promote the understanding of the pathogenesis and immunoregulation of EAT.
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PMID:Cloning and characterization of murine thyroglobulin cDNA. 934 6

A novel lectin has been purified from the fruiting bodies as well as cultured mycelia of the edible mushroom Volvariella volvacea. The lectin, designated as VVL, was a homodimeric protein with a molecular weight of 32 kDa as demonstrated by gel filtration and SDS-PAGE. VVL had no carbohydrate moiety, and its hemagglutinating activity was inhibited by thyroglobulin but not by simple carbohydrates such as monomeric or dimeric sugars. The immunomodulatory activity of VVL was demonstrated by its potent stimulatory activity toward murine splenic lymphocytes. VVL was also found to markedly enhance the transcriptional expression of interleukin-2 and interferon-gamma by reverse transcriptase-polymerase chain reaction. As revealed by its N-terminal amino acid sequence, VVL possessed a molecular structure distinct from other immunomodulatory proteins previously reported in the same fungus.
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PMID:A novel lectin with potent immunomodulatory activity isolated from both fruiting bodies and cultured mycelia of the edible mushroom Volvariella volvacea. 963 63


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