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)

We examined the effect of nerve growth factor (NGF) on the expression of low-affinity NGF receptor (LNGFR) in cultured P3 basal forebrain cholinergic neurons, on which NGF acts to promote differentiation. Based on the results of the RT-PCR (reverse transcriptase-polymerase chain reaction) method, over a 2-fold increase in the LNGFR mRNA level was found in NGF-treated cultures compared with control cultures at one day after the addition of 100 ng/ml NGF. This increase was maintained for up to 3 days after the addition of NGF. The increase in LNGFR mRNA was found even at 1 ng/ml NGF (= 40 pM), indicating that the up-regulation of the LNGFR mRNA level in cultured cholinergic neurons occurred at an NGF concentration near the Kd value for the high-affinity NGF receptor. In addition, immunohistochemical staining showed stronger staining with a monoclonal anti-LNGFR antibody of the cholinergic neurons in NGF-treated cultures than those in control cultures. Our results suggest that NGF can up-regulate LNGFR expression at the mRNA and protein levels in cultured P3 basal forebrain cholinergic neurons and that this mechanism may play an important role in potentiating the effect of NGF on these neurons.
Brain Res Mol Brain Res 1992 Dec
PMID:Nerve growth factor (NGF)-mediated up-regulation of low-affinity NGF receptor gene expression in cultured basal forebrain cholinergic neurons from postnatal 3-day-old rats. 133 36

We have isolated a bovine prolactin (bPRL) receptor cDNA from an endometrial cDNA library, which predicts a 557 amino acid transmembrane protein similar to the long forms of other characterized prolactin receptors. The predicted cytoplasmic domain is slightly truncated primarily by a stop codon located 36 codons 5' from the stop utilized in the human hepatic transcript. When expressed in COS cells, this cDNA was shown to encode a protein which bound bovine placental lactogen (bPL) and bPRL with nearly equal affinity (KD for bPL, 2.03 x 10(-10) M; bPRL, 3.07 x 10(-10) M). Northern analysis demonstrated multiple transcripts, with maternal liver, corpus luteum, intestine, endometrium and fetal liver containing a major transcript of about 3.8 kb, and maternal corpus luteum and endometrium, a second sized transcript of apparently equal abundance of 4.4 kb. This difference did not appear to be within the coding region. Primer extension analysis of maternal hepatic and endometrial transcripts revealed considerable heterogeneity. Examination of the distribution of prolactin and growth hormone receptor transcripts at mid-pregnancy by semi-quantitative reverse transcriptase polymerase chain reaction showed that both are widespread in bovine fetal and placental tissues. This isolation of bovine prolactin receptor cDNA, and description of receptor distribution will facilitate study of the action of the placental and pituitary members of this gene family during pregnancy.
Mol Cell Endocrinol 1992 Nov
PMID:Molecular cloning of the bovine prolactin receptor and distribution of prolactin and growth hormone receptor transcripts in fetal and utero-placental tissues. 133 25

Paget's disease of bone is a disease of unknown etiology. The demonstration of viral-like particles on ultrastructural examination and the putative detection of viral antibodies and nucleic acids in the tissues suggest a possible viral association. The purpose of this study was to search for nucleic acid sequences homologous to measles virus using the recently described reverse transcriptase (RT) polymerase chain reaction (PCR) in situ hybridization (ISH) technique. After performing RT PCR ISH utilizing primers specific for the nucleocapsid region of the measles virus, an intense signal was evident in most measles-infected HeLa cells compared with a weak signal in few of these cells using standard cDNA-RNA ISH analysis. Amplified measles nucleic acid was detected in tissue from a patient who died of measles infection and was not detected in any of the 11 cases of Paget's disease of bone studied or in a giant cell tumor of bone that had tubuloreticular inclusions on electron microscopy. Therefore, these data suggest that infection by the measles virus is not associated with Paget's disease of bone.
Diagn Mol Pathol 1992 Dec
PMID:In situ analysis of Paget's disease of bone for measles-specific PCR-amplified cDNA. 134 74

In rats, gamma-glutamyl transpeptidase (gamma GT) exists as a single-copy gene, and three distinct species of RNA (types I, II, and III) that differ in their 5' untranslated regions have been identified. To compare steady-state levels of these gamma GT RNAs in rat tissues, hepatic carcinomas, and cultured cells, we used RNA dot-blot hybridization and a reverse transcriptase-polymerase chain reaction (RT-PCR) technique with oligonucleotides specifically designed for each type of RNA. Fetal liver, hepatic carcinomas, rasT24-transformed rat liver epithelial (RLE) cells and pancreas make only type III RNA. Liver and untransformed RLE cells do not make detectable levels of gamma GT RNA. We found that both fetal and adult kidneys synthesize all three types of RNA, indicating that increases in gamma GT RNA known to occur after birth do not result from recruitment of additional RNA species. When we increased the sensitivity of the assay approximately 1000 fold by sequencing the RT-PCR product directly after an additional round of amplification, we found that very low levels of types I and II RNA were present in fetal liver, rasT24-transformed RLE cells, and pancreas, and that adult liver and untransformed RLE cells synthesized very low levels of all three RNA species. Rat-1 fibroblasts did not make levels of gamma GT RNA detectable by this method. These results demonstrate that different gamma GT RNA species are regulated differently during development and neoplastic transformation and that there is a commitment in some cell types to very-low-level expression of gamma GT RNAs.
Mol Carcinog 1992
PMID:The same gamma-glutamyl transpeptidase RNA species is expressed in fetal liver, hepatic carcinomas, and rasT24-transformed rat liver epithelial cells. 134 50

Luteinizing hormone/chorionic gonadotropin (LH/CG) receptor complementary DNA (cDNA) isoforms were amplified using pseudopregnant rat ovarian total RNA as a template and the primers reaching over the coding regions at both ends in a reverse transcriptase-polymerase chain reaction (RT-PCR). Agarose gel electrophoresis of the PCR products revealed three bands corresponding to about 2.1, 2.0 and 1.8 kilobases (kb). Subcloning of pooled PCR products into EcoRI site of pUCBM20 resulted in 167 clones, from which five different restriction patterns were obtained by digestion with EcoRI and HaeIII. One clone of each was further characterized. It could be predicted from the nucleotide sequences that the clone rLHR2100 encoded a full-length receptor (a 674 amino acid mature protein), the clone rLHR2075 lacked part of exon IX (nucleotides 693-717) and encoded a truncated 225 amino acid mature protein, the clone rLHR1950 lacked exons III and IV (nucleotides 246-395) and encoded a nearly full-length protein (a 624 amino acid mature protein), and the clones rLHR1834 and rLHR1759 lacked the same part of exon XI (nucleotides 960-1225), with exon V (nucleotides 396-470) also absent in the latter, the deletion in exon XI leading both these clones to premature termination. The clone rLHR1834 encoded a 316 amino acid mature protein and rLHR1759 a 291 amino acid mature protein, respectively. The sequence data suggest that all of these isoforms contain the putative signal sequence and are derived from a single copy gene via alternative splicing. These results point further to the fact that the expression of the 90 kDa LH/CG receptor is regulated via an extensive alternative splicing of the receptor gene primary transcript.
Mol Cell Endocrinol 1992 Mar
PMID:Expression of the LH/CG receptor gene in rat ovarian tissue is regulated by an extensive alternative splicing of the primary transcript. 135 63

The reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) is present in virions and infected cells as an heterodimer (p66/p51). A new class of potent and selective HIV-1 inhibitors, the tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-one and -thione (TIBO) derivatives, were found to exert their antiviral activity by interacting with monomeric HIV-1 RT (p66) in a way different from that of previously studied RT inhibitors such as azidothymidine 5'-triphosphate. Upon examination of the kinetic properties of the heterodimeric HIV-1 RT and its inhibition by TIBO compounds, a positive cooperativity between the subunits of the enzyme with regard to the 2'-deoxynucleoside 5'-triphosphates and the template/primer was observed. The cooperativity with respect to the template/primer may result from a progressive dimerization in the presence of increasing concentrations of the template/primer, a process referred to as polysteric linkage. Because the cooperativity of p66/p51 was abolished in the presence of TIBO, these compounds behave as allosteric inhibitors.
Mol Pharmacol 1992 Jan
PMID:Allosteric inhibition of human immunodeficiency virus type 1 reverse transcriptase by tetrahydroimidazo[4,5,1-jk][1,4]benzodiazepin-2(1H)-one and -thione compounds. 137 Jul 7

We have used the polymerase chain reaction to analyse Ty1-copia group retrotransposons of flowering plants. All eight species studied contain reverse transcriptase fragments from Ty1-copia group retrotransposons. Sequence analysis of 31 subcloned fragments from potato reveals that each is different from the others, with predicted amino acid diversities between individual fragments varying between 5% and 75%. Such sequence heterogeneity within a single species contrasts strongly with the limited diversity seen in such retrotransposons in yeast and Drosophila. The fragments from the other seven plant species examined are also heterogeneous, both within and between species, showing that this is a general property of this transposon group in plants. Phylogenetic analysis of all these sequences reveals that many of them fall into subgroups which span species boundaries, such that the closest homologue of one sequence is often from a different species. We suggest that both vertical transmission of Ty1-copia group retrotransposons within plant lineages and horizontal transmission between different species have played roles in the evolution of Ty1-copia group retrotransposons in flowering plants.
Mol Gen Genet 1992 Jan
PMID:Extreme heterogeneity of Ty1-copia group retrotransposons in plants. 137 Sep 76

The in vitro fidelity of reverse transcriptase from human immunodeficiency virus type I (HIV-1 RT) upon copying an RNA template was measured using the phi Xam 16 reversion assay. A phi X174 sequence harboring the amber 16 codon was cloned into a transcription vector. RNA obtained from transcription by bacteriophage T7 RNA polymerase was used as a template for RNA-directed DNA synthesis by HIV-1 RT. An imbalance of dNTP concentrations during the reverse transcription step served to distinguish between errors that arose from the transcription step and errors from reverse transcription. The frequency of dGTP.U mismatches was determined to be 1/360, while dGTP.rA mismatches formed at a rate of 1/4600. These are 20-fold and sevenfold higher, respectively, than the error rates determined for the same sequence with a DNA template. Due to a high background of errors in the RNA template originating from the transcription step only upper limits for the frequency of three other mismatches can be given. The data indicate that the reverse transcription step of the HIV-1 replication cycle contributes significantly to the generation of mutant viruses.
J Mol Biol 1992 Feb 05
PMID:Fidelity of human immunodeficiency virus type I reverse transcriptase in copying natural RNA. 137 12

The modulation of the rat cortical m1 muscarinic receptor mRNA was studied with a method of quantitation using the polymerase chain reaction after conversion to complementary DNA (cDNA) with AMV reverse transcriptase (RT/PCR). Primers specific to the C3 region of the m1 mRNA were employed. The y-intercepts from the linear regions of semilogarithmic plots of PCR product versus cycle number were used as measures of the levels of m1 muscarinic mRNA-measured relative to that of glyceraldehyde phosphate dehydrogenase (GAPDH) mRNA (the 'ratio' method). Alternatively, m1 mRNA in total cortical RNA samples was quantitated from the increase in product elicited by adding a known amount of exogenous m1 muscarinic cDNA sequence (the 'spiking' method). This allowed calculation of absolute level of m1 mRNA, which was 4.1 pg/micrograms total RNA. We measured the level of the rat cortical m1 mRNA after 1 week of chronic receptor blockade with atropine, showing upregulation of 154% by the GAPDH/m1 ratio method and 145% by the spiking method. That this transcriptional alteration was specific was indicated by the finding that the level of GAP-43 mRNA was not affected by atropine treatment.
Brain Res Mol Brain Res 1992 Jan
PMID:Chronic atropine administration up-regulates rat cortical muscarinic m1 receptor mRNA molecules: assessment with the RT/PCR. 137 72

2',3'-Dideoxyuridine (ddU) is ineffective at controlling human immunodeficiency virus type 1 (HIV-1) infection in human T cells, because it is not biotransformed to the active 5'-triphosphate. The metabolic block resides in the poor substrate affinity of ddU for cellular nucleoside kinases. This problem cannot be overcome by supplying the preformed nucleotides, because such compounds are unable to penetrate cells. To circumvent the requirement of ddU for enzymic phosphorylation, we have prepared bis(pivaloyloxymethyl) 2',3'-dideoxyuridine 5'-monophosphate (piv2 ddUMP), as a potential membrane-permeable prodrug of ddUMP, and investigated its metabolism and anti-HIV activity in two human T cell lines, one with wild-type thymidine kinase activity (MT-4) and the other deficient in thymidine kinase activity (CEM-tk-). The 5'-mono-, di-, and triphosphates of ddU were formed in both cell lines after exposure to piv2-ddUMP. In contrast, phosphorylated metabolites were not observed in cells treated with ddU or ddUMP alone. piv2-ddUMP also reduced the cytopathic effects of HIV-1 in MT-4 cells (ED50, 4.75 microM) and inhibited virus production in culture fluid (ED50, 20 microM). In addition, piv2-ddUMP protected CEM-tk- cells from HIV-1 infection, as demonstrated by inhibition of intracellular p24 antigen levels (ED50, 3 microM) and reverse transcriptase activity in culture medium (Ed50, 2.5 microM). Based on these findings, we propose that the "masked nucleotide" strategy may make available for development nucleoside analogues hitherto considered inactive because of failure to undergo biotransformation to the corresponding 5'-monophosphates. Moreover, by circumventing metabolic dependency on nucleoside kinases, the strategy may overcome acquired resistance to nucleoside analogues caused by the loss or depletion of nucleoside kinases.
Mol Pharmacol 1992 Mar
PMID:Membrane-permeable dideoxyuridine 5'-monophosphate analogue inhibits human immunodeficiency virus infection. 137 82


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