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)

We investigated the effect of retinoids on fetal lung development in the rat. The concentration of retinyl palmitate increased rapidly to a peak on day 17 of gestation and decreased to a minimum on day 21 of gestation; there was a slight increase after birth. Retinoid acid receptor (RAR)-alpha and -beta mRNA were detected in all samples obtained from perinatal and adult rat lung, and only a trace of RAR-gamma mRNA was detected in the fetuses on days 15, 17 and 19 of gestation and in the adults by reverse transcriptase-polymerase chain reaction. After a maternal retinol deficiency of 28 days' duration, fetal body and lung weights were significantly lower than those of controls; the concentrations of retinyl palmitate and phosphatidylcholine (PC) in the lung after a maternal retinol deficiency of 14, 21, or 28 days were significantly lower than those of controls. Expression of RAR-beta mRNA in the group with 28-day retinol deficiency was lower than in controls, that of RAR-alpha mRNA was increased and that of RAR-gamma mRNA was not influenced by retinol deficiency. The rate of choline incorporation into PC in fetal lung explants was significantly higher in the group treated with retinoic acid (RA) than in controls. RA enhanced the effect of epidermal growth factor on choline incorporation and prevented that of dexamethasone.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of retinoids on fetal lung development in the rat. 754 61

Calcyclin gene, a Ca(2+)-binding protein with homology to S-100, has been found to be expressed at different levels in leukaemic cells and in other tumour cells. We recently reported the expression of the gene in human neuroblastoma (NB) cell lines, and suggested a possible role of calcyclin in cell differentiation. To extend our findings, we investigated the expression of the gene in NB cells induced to differentiate by retinoic acid (RA), using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. Time-course experiments employing LA-N-5 cells showed that calcyclin mRNA appeared 2 h after RA treatment, long before the cells were blocked in the G1 cell-cycle phase and before the neurite-like structures outgrew from the cell bodies. This suggests the involvement of the gene in the early phase of cell differentiation. Furthermore, we investigated mRNA expression in a series of fresh neuroblastomas. NB tumours showed a heterogeneous pattern of calcyclin expression, although calcyclin seemed to be expressed more frequently in cases with a favourable Shimada histology. We also studied the expression of the protein in formalin fixed and paraffin embedded tissues, by using a specific anticalcyclin antibody. The protein was detected in stromal cells which characterise a more mature histological type, and in nerve sheaths, whereas neuroblasts were negative. The tissue that expressed calcyclin protein showed a Schwann-like differentiation and, unlike S-100 protein, calcyclin was expressed in the perineurium.
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PMID:Gene expression and protein localisation of calcyclin, a calcium-binding protein of the S-100 family in fresh neuroblastomas. 757 53

Of 113 acute promyelocytic leukemia cases documented to have diagnostic PML-RAR alpha hybrid mRNA, 10 cases (8.8%) had fusion sites in PML gene exon 6 (V-forms) rather than in the two common hybrid mRNA configurations resulting from breaksites in either PML gene intron 6 (L-forms) or intron 3 (S-forms). In 4 V-form cases, a common break/fusion site was discovered at PML gene nucleotide (nt) 1685, abutting a 3' cryptic splice donor sequence. The fusion site was proximal to the common site in 1 case and more distal in 5 cases. The open reading frame encoding a PML-RAR alpha gene was consistently preserved, either by an in-frame fusion site or by the insertion of 3 to 127 unidentified nts. In 2 V-form cases, hybridization analysis of the reverse transcriptase-polymerase chain reaction products with a PML-RAR alpha juction probe was required for discrimination from L-form cases. Two V-form subgroups were defined by in vitro sensitivity to all-trans retinoic acid (tRA)-induced differentiation: 4 of 4 cases tested with fusion sites at or 5' to nt 1685 (subgroup E6S) had reduced sensitivity (EC50 > or = 10(-7) mol/L), whereas 4 of 4 cases with fusion sites at or 3' to nt 1709 (subgroup E6L) had high sensitivity (EC50 < 10(-8) mol/L) indistinguishable from that of L-form and S-form cases. These results provide the first link between PML-RAR alpha configuration and tRA sensitivity in vitro and support the importance of subclassifying APL cases according to PML-RAR alpha transcript type.
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PMID:Characterization of acute promyelocytic leukemia cases with PML-RAR alpha break/fusion sites in PML exon 6: identification of a subgroup with decreased in vitro responsiveness to all-trans retinoic acid. 763 62

Poly(A)+RNA composition differences for normal, fetal and cirrhotic human liver before and after retinoic acid-induced differentiation of the F9 embryonal carcinoma cell line were analyzed by a novel poly(A)+RNA patterns method. The method is based on the polyacrylamide gel electrophoretic analysis of short cDNA termination products, synthesized by reverse transcriptase using poly(A)+RNA as a template, a set of short 5'-end labeled primers, three natural and one terminator deoxyribonucleotide. A number of known differentially expressed genes and some unknown ones were then identified by direct sequencing of the differentially represented bands excised from a gel and searching a complementary mRNA target sites in Genbank database.
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PMID:Application of poly(A)+RNA patterns method for searching of differentially expressed genes. 768 93

Two new myeloid cell lines (K051 and K052) were established from a patient with multilineage CD7-positive acute leukemia. The K051 and K052 were established from the patient's bone marrow cells at diagnosis and at relapse, respectively. The K051 cell expressed myeloid-associated antigens (CD13 and CD33), a platelet-associated antigen (CD41), and an erythroid antigen (glycophorin A). The K052 cell expressed myeloid-associated antigens (CD13, CD14, and CD33), lymphoid markers (CD2, CD5, and CD7), and HLA-DR. Chromosome analysis of both cell lines showed a 17p- chromosome. Both cell lines were investigated for aberrations of the p53 gene and the N-ras gene. A p53 mutation detected in both cell lines consisted of a C-->T substitution in codon 248. An N-ras mutation detected only in the K052 cell consisted of a G-->C substitution in codon 13. Expression of the multidrug resistance gene (MDR1) was also investigated by the semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). MDR1-mRNA was more highly expressed by the K052 cell than the K051 cell, being equivalent to that in HEL cells. The functional MDR1-protein against vincristine was also observed, and its function was inhibited by verapamile and Cyclosporin A. The K052 cells were capable of phenotypic or morphologic differentiation after being incubated with granulocyte colony-stimulating factor, interleukin-2, phorbol 12-myristate 13-acetate, or 1,25-dihydroxy-vitamin D3. In contrast, the K051 cells responded phenotypically to retinoic acid. Thus, the K051 and K052 cell lines will be useful for investigating the cellular and molecular events in leukemogenesis and differentiation, and the mechanism of expression of the MDR1 gene.
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PMID:p53 and N-ras mutations in two new leukemia cell lines established from a patient with multilineage CD7-positive acute leukemia. 769 50

Minimal residual disease (MRD) was prospectively monitored at the 10(-5) level by the reverse transcriptase-polymerase chain reaction (RT-PCR) of PML-retinoic acid receptor alpha (RARA) transcripts from 27 acute promyelocytic leukemia (APL) patients who achieved complete remission (CR) with all-trans retinoic acid and chemotherapy (previously untreated patients, 15; refractory to chemotherapy or relapsed, 12). The RNA quality from bone marrow cells was firstly assessed by gel electrophoresis to avoid false negativity because of the fragility of the APL cells and the PML-RARA transcripts. In 12 of 15 untreated patients, RT-PCR became negative during consolidation and intensification therapy 4-16 months after the initiation of therapy, whereas it remained positive in nine of 12 refractory patients. At the end of therapy, RT-PCR was negative in 14 patients and positive in 13 patients. The former patients remained in CR at median follow-up of 9 months after the end of therapy. In the latter, however, 10 patients relapsed at a median of 5 months after the end of therapy. These results suggest that the RT-PCR assay can evaluate the quality of CR in APL and predict subsequent relapse.
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PMID:Prognostic significance of the RT-PCR assay of PML-RARA transcripts in acute promyelocytic leukemia. The Leukemia Study Group of the Ministry of Health and Welfare (Kouseisho). 772 89

Retinoids have been shown to influence pattern formation during development and regeneration in numerous systems such as limbs, vertebrae, and neural tube although there is little information about the effects of retinoids on pattern formation in visceral organs. We investigated the effects of exogenous retinoic acid on the in vitro pattern of airway branching and on lung epithelial cell differentiation. Histology, [3H]thymidine autoradiographies and reverse transcriptase/polymerase chain reaction (RT/PCR) amplification were used to assess the effects of retinoids and the expression of lung epithelial markers of differentiation. We found that retinoic acid interferes, in a dose-dependent fashion, with the expression of epithelial genes that are found in distal segments of the fetal lung (surfactant-associated proteins SP-A, SP-B, and SP-C). At high concentrations, retinoic acid (RA) dramatically altered the developmental pattern of the lung, favoring growth of structures that resemble proximal airways and concomitantly suppressing distal epithelial buds. We hypothesize that this in vitro "proximalizing" effect on the developing lung may be related to alterations in the expression of pattern-related genes.
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PMID:Retinoic acid induces changes in the pattern of airway branching and alters epithelial cell differentiation in the developing lung in vitro. 774 11

Drug metabolizing enzymes, particularly those involved in the metabolism of carcinogenic chemicals, were characterized in cultured human keratinocytes. Using immunoblotting experiments, we analysed the expression of phase I enzymes, cytochrome P4501A1 (CYP1A1) and NADPH reductase, and phase II enzymes, phenol UDP-glucuronosyltransferase (UGT) and glutathione S-transferase (GST) isoform pi, in the presence of either classical inducers (i.e. 3-methylcholanthrene, dimethylbenz[a]anthracene, phenobarbital, and clofibrate) or all-trans retinoic acid (RA). This study has shown that the expression of CYP1A1 and UGT is concomitantly induced by 3-methylcholanthrene, dimethylbenz[a]anthracene, and RA, and that of NADPH reductase is only enhanced by phenobarbital and RA. In contrast, the expression of GST pi was not affected by the inducers. Using the reverse transcriptase-polymerase chain reaction, we have demonstrated that the effects of 3-methylcholanthrene, dimethylbenz[a]anthracene and RA on CYP1A1 expression correlate with an increase of CYP1A1 mRNA level. Our results indicate that, with the exception of clofibrate, xenobiotics and RA differentially modulate the expression of drug metabolizing enzymes.
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PMID:Constitutive and inducible expression of drug metabolizing enzymes in cultured human keratinocytes. 775 27

To determine cis-acting elements controlling the rat B-50/GAP-43 gene expression, the genomic DNA encoding exon 1 and the 5' flanking sequence was isolated. Sequence analysis of 1 kb 5' untranslated region (UTR) revealed the presence of a (GA)-repeat and a (GT)-repeat. The size of the (GA)-repeat varied due to both an instability of phage lambda lambda DNA in E. coli and genomic variation between rats. Transcription initiation sites were mapped in 8-day-old rat brain poly(A)+ mRNA. Primer extension indicated multiple transcription start sites at -159 and -339/-342 nt upstream of the translation start site; reverse transcriptase coupled PCR showed that the most 5' transcription start site is located between -465 and -440. Northern blotting demonstrated that approximately 90% of the B-50 mRNAs initiates at approximately -50. Promoter analysis by transient transfection assays in undifferentiated and retinoic acid-differentiated P19-EC cells revealed that the rat B-50 gene contains two promoters. P1 (located between -750 and -407) contains commonly observed promoter elements such as a TATA box and CCAAT boxes. P2 (located between -233 and -1) neither contains TATA boxes, CCAAT boxes nor consensus sequences of house-keeping gene promoters like GC-boxes. The activity of P1 is inhibited at neuroectodermal differentiation of P19-EC cells whereas the activity of P2 is stimulated. In 8 day old rat brain the majority of the B-50 mRNA transcripts are derived from P2. It is concluded that at this developmental stage P2 is the most important promoter.
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PMID:Identification of two promoter regions in the rat B-50/GAP-43 gene. 805 79

The effects of retinoids are mediated by two types of receptors, the retinoic acid receptors (RARs) and the retinoid-X-receptors (RXRs). The physiological ligand of the RARs is all-trans-retinoic acid whereas RXRs have high affinity for 9-cis-retinoic acid, a naturally occurring retinoid isomer. RXRs are broadly expressed in embryonic and adult tissues, and they are capable of forming homodimers as well as heterodimers with RARs and other nuclear hormone receptors. The role of 9-cis-retinoic acid in regulating the activity of RXR homodimers and RXR-containing heterodimers is poorly understood in vivo. To begin to explore the function of 9-cis-retinoic acid in morphogenesis, we have examined the activity of this isomer in the chick wing. Using reverse transcriptase polymerase chain reaction analyses, we show that RXR gamma is expressed in stage 20 wing buds. Similar to all-trans-retinoic acid, the 9-cis-isomer induces pattern duplications when locally applied to chick wing buds, but the 9-cis isomer is about 25 times more potent than the all-trans form. Furthermore, applied all-trans-retinoic acid is converted to the 9-cis isomer in the wing bud. The ratio of 9-cis to all-trans-retinoic acid established in the tissue is approximately 1:25. This quantitative agreement between the degree of conversion and the 25-fold higher efficacy of the 9-cis isomer, raises the possibility that, at least in part, the effects of all-trans-retinoic acid on the wing pattern result from a conversion to the 9-cis isomer.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:9-cis-retinoic acid, a potent inducer of digit pattern duplications in the chick wing bud. 807 28


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