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)

Human choriocarcinoma cells of the JAR line, with no demonstrable surface CD4 receptor were infected with human immunodeficiency virus type 1 (HIV-1), strain RF. Primer-directed enzymatic DNA amplification (polymerase chain reaction, PCR) detected the presence of viral DNA when the cultures were investigated at day 5 post-infection (p.i.). The absence of cytopathic changes attributable to virus replication suggested silent infection of these malignant trophoblastic cells. Neither reverse transcriptase (RT) activity nor HIV-specific antigens were found in the culture nutrient medium during JAR cell propagation. However, when the HIV-carrier JAR cells were continuously cultured and the cocultivation was initiated with CEM-SS lymphoblastoid cells after two subsequent passages, rescue of infectious virus was observed.
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PMID:In vitro productive infection of human malignant trophoblastic cell line JAR with human immunodeficiency virus type 1 (HIV-1). 168 80

Attempts to assess human placental GH variant (hGH-V) and chorionic somatomammotropin (hCS) RNA in choriocarcinoma cell lines have been hampered by low levels of expression and limited sensitivity of RNA blotting analysis. We examined human choriocarcinoma BeWo, JAR, and JEG-3 cell lines as well as samples of complete hydatidiform moles for expression of members of the human GH (hGH) gene family using reverse transcriptase-polymerase chain reaction. A single and common set of primers was designed and used to detect products of the hGH/hCS genes as well as distinguish processed RNA from any contaminating DNA. Transcripts from the hCS genes hCS-A and -B were distinguished from placental hGH variant (hGH-V) and hCS-like (hCS-L) gene RNA by diagnostic restriction digestion of the polymerase chain reaction products. The expected pattern of hGH/hCS RNA expression was detected in term placenta, where hCS and hGH-V/hCS-L transcripts represented approximately 95% and approximately 5% of the total hGH/hCS RNA, respectively. The level of hCS RNA varied from 22-99% of the total hGH/hCS RNA in the neoplastic trophoblast samples, and variable levels of hGH-V and hCS-L RNA were also observed. In choriocarcinoma JAR cells, hGH-V RNA represented approximately 78% of the total hGH/hCS RNA compared to approximately 22% for hCS. Further, although low hCS-L RNA levels (< 1%) were found in term placenta and two of the hydatidiform moles, hCS-L transcripts represented 11% of the total hGH/hCS RNA in a third hydatidiform mole. Finally, in contrast to the detection of variable levels of hCS-L RNA in term placenta and hydatidiform mole samples, no hCS-L transcripts were detected in the three choriocarcinoma cell lines examined. These patterns reflect either deregulated hGH/hCS gene expression in neoplastic trophoblasts or differences that accompany the process of differentiation of trophoblast subpopulations. Regardless, this suggests that the control of hGH-V and hCS-L gene expression is distinct from that of the hCS-A and hCS-B genes and raises questions about the possible involvement of hGH/hCS family members in the pathology of placental abnormalities.
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PMID:Detection of placental growth hormone variant and chorionic somatomammotropin ribonucleic acid expression in human trophoblastic neoplasms by reverse transcriptase-polymerase chain reaction. 751

Particles with the characteristic shape of enveloped retroviral particles and maximal specific reverse transcriptase (RTase) activity at buoyant density of 1.15-1.17 g/ml have been isolated from human first-trimester chorionic villous tissue. Murine monoclonal antibodies (mAbs) to these isolated particles were generated. One IgM mAb (RV3-27) showed granular staining of cytoplasmic structures within syncytiotrophoblast by immunohistochemistry. Immunoelectron microscopic studies have demonstrated focal localisation to small submembranous regions of syncytiotrophoblast, as well as reaction with detergent-disrupted isolated placental retroviral-like particles. The RV3-27 mAb did not stain other human tissues in this focal manner, although increased generalised cytoplasmic staining was not uncommon; also, this mAb did not react strongly with the surface or cytoplasm of a variety of human cell lines (including choriocarcinoma cells). Immunoblotting and HPLC analyses have indicated the reactive placental antigen to be a 17-25 kDa protein. It is suggested that the RV3-27 mAb may be reactive with a syncytiotrophoblast antigen encoded by an endogenous retroviral sequence.
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PMID:A murine monoclonal antibody (RV3-27) raised against isolated human placental endogenous retroviral particles and reactive with syncytiotrophoblast. 752 69

We investigated permissiveness of the malignantly transformed trophoblast (choriocarcinoma) cell lines JAR, BeWo and JEG-3 to the human T cell lymphotropic virus type I (HTLV-I). After co-culture with the productively infected cell line MT-2 the choriocarcinoma cell lines were analysed for infection over a period of three months. The presence of HTLV-I viral DNA was examined by PCR using primers targeting the gag, pol, env and pX specific sequences. All amplified segments were found consistently in the cell cultures throughout the period of study. Further analysis that aimed to characterize the size variation of the integrated proviral DNA by Southern blotting revealed the presence of integrated proviral sequences which consisted, for the most part, of incomplete genomes. The presence of the full-length HTLV-I genome, however, was unequivocally confirmed in clonally expanded cell cultures derived from the originally infected parental cells. In order to analyse virus expression at the transcriptional level, we used reverse transcriptase (RT)-mediated PCR that was targeted at intra-exon regions (gag, pol, env and pX), and the splicing sites of the env and pX-tax/rex mRNAs. When compared with MT-2 cells, substantially lower levels of all transcripts were found in all the cell lines analysed. We were unsuccessful in attempts to detect viral protein expression using polyvalent or Tax- and Gag-specific monoclonal antibodies by Western blot analysis or immunoprecipitation, and we could not detect any RT activity released into the supernatant of the infected cells either. Collectively, these data suggest that the trophoblastic cells may become persistently but essentially non-productively infected with HTLV-I.
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PMID:Cell-mediated transmission of human T cell lymphotropic virus type I to human malignant trophoblastic cells results in long-term persistent infection. 784 28

An in vitro model of placental infection by human immunodeficiency virus type 1 (HIV-1) was established using human choriocarcinoma-derived trophoblast lines exposed to free HIV-1 or HIV-1-infected lymphocytic and monocytic cells. Virus infectivity was evaluated by measuring both the levels of p24 HIV-1 antigen and reverse transcriptase activity either from indicator MT-4 lymphocytes after co-cultivation with infected trophoblasts or directly from trophoblast cultures. None of the tested trophoblast lines were permissive, in a detectable manner, to infection by cell-free virus. Furthermore, there were no signs of infection when trophoblasts were exposed to HIV-1-carrying ACH-2 and U1 cells with impaired adhesion capacity. However, the exposure to MOLT-4/IIIB lymphocytes or U937/YH5 monocytes that adhere to substrate cells resulted invariably in productive infection. The ultrastructure of the trophoblasts suggests endocytosis of HIV-1. It appears that the infection of the host cell results from the escape of virions from degradation in lysosomes. Alternatively, HIV-1 may enter by budding directly from the lymphocyte surface into the cytoplasm of trophoblasts. These results confirm previous studies and suggest that CD4-negative placental trophoblasts--the only foetal cells in direct contact with maternal blood--can be susceptible to HIV-1 infection.
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PMID:Human immunodeficiency virus type 1 infection of choriocarcinoma-derived trophoblasts. 810 49

Because the fetus is semiallogenic to the mother, considerable modulation of the maternal immune response must occur in order for pregnancy to be successfully carried to term. Some authors have hypothesized that the immunomodulation of pregnancy includes an adjustment of cytokine responses away from the Th1 paradigm and toward the Th2 pattern. In vivo data from murine pregnancy support this hypothesis. However, in humans, the Th1/Th2 model appears to be more complex than that in mice, and cytokine expression of mRNA in human decidual tissue does not reflect a clear-cut Th2 bias. The experiments described here were undertaken to determine whether and how trophoblastic cells modulate cytokine expression in activated lymphocytes, and whether there is a trend toward the use of the Th2 pattern in an experimental model of the maternal-fetal interface. We used reverse transcriptase polymerase chain reaction (rtPCR) to detect cytokine mRNA expression in human peripheral blood mononuclear cells cocultivated with human choriocarcinoma JAR cells. We found that although IL-2 (a paradigmatic Th1 cytokine) was significantly down-regulated by JAR cells at the mRNA level, similar decreases were also seen in IL-10, which participates in the Th2 paradigm. We were unable to detect changes in either interferon-gamma (IFN-gamma, a Th1 cytokine) or IL-4 (a Th2 cytokine) mRNA's or in IL-2R expression by fluorescence-activated cell sorting. These studies indicate that human choriocarcinoma JAR cells are capable of modifying cytokines in activated lymphocytes other than those involved in the Th1 paradigm. While it may be useful to view human responses against the background of these patterns established from murine systems, it is reasonable to conclude that human pregnancy may not involve regulation of Th1 immune responses exclusively.
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PMID:Regulation of cytokine mRNA expression in activated lymphocytes by human choriocarcinoma JAR cells. 864 Aug 72

The growth of tumor cells can be regulated by a variety of cytokines. To investigate the pathogenesis of choriocarcinoma and explore a new therapeutic approach for the carcinoma, we examined the role of IL-6 in the growth of a human choriocarcinoma cell line (JEG-3). IL-6 was identified in the supernatant of the cell culture medium by enzyme-linked immunosorbent assay, indicating that this cell secreted IL-6. The mRNAs of IL-6, IL-6 receptor and gP130, the IL-6 signal transducer, in this cell were shown to be present by reverse transcriptase polymerase chain reaction assay and confirmed by Southern blot hybridization and direct sequencing. The addition of hrIL-6 to the cell culture failed to stimulate cell growth. Monoclonal antibodies against IL-6, IL-6 receptor, and gP130 were also unable to inhibit the proliferation of this cell line. The antisense oligonucleotides targeting IL-6 mRNA, however, inhibited both cell growth and IL-6 production. Taken together, these findings indicate that endogenous IL-6 plays an important role in the growth of the JEG-3 cell line, and it exerts its action by an intracellular autocrine growth mechanism. The results also suggest that the therapeutic trials with monoclonal antibodies designed to neutralize IL-6 or block its receptor will likely fail, whereas the antisense oligonucleotides targeted to IL-6 mRNA may have some value for the treatment of choriocarcinoma and other cancers with intracellular autocrine growth fashion mediated by IL-6.
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PMID:IL-6 antisense-mediated growth inhibition of a choriocarcinoma cell line: an intracellular autocrine growth mechanism. 889 73

The aims of this study were to establish whether both the cystic fibrosis (CF) and multidrug resistance (MDR1) genes are expressed in the human placenta during development and differentiation. To study their pattern of expression during development, RNA was extracted from first, second and third trimester human placentas. To investigate differentiation, RNA was extracted from cytotrophoblast cells isolated from human term placentas and maintained in culture for 18, 66, 90 and 114 h and from the undifferentiated choriocarcinoma cell line JAr. Using the reverse transcriptase-polymerase chain reaction (RT-PCR) with gene specific, intron spanning primers, a cDNA product of 1 kb, as expected for CF expression, was detectable following 35 cycles of PCR from all RNA samples except those from JAr; in the latter a product was only detected in one sample out of four separate passages and this was only just detectable after 40 cycles of PCR. RT-PCR using MDR1 specific primers resulted in a product from all samples at 0.34 kb as expected if this gene is expressed. These results demonstrate that both the CF and MDR1 genes are expressed in the human placenta at all stages of development and differentiation, although the expression of the CF, but not the MDR1, gene appears to be much weaker in the undifferentiated JAr cells in comparison with cytotrophoblast cells.
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PMID:Expression of the cystic fibrosis (CF) and multidrug resistance (MDR1) genes during development and differentiation in the human placenta. 923 84

Endoglin is an integral membrane glycoprotein that binds transforming growth factor-beta1 (TGF-beta1) with high affinity and it is strongly expressed on syncytiotrophoblasts throughout pregnancy. Here, we describe the expression of endoglin by the choriocarcinoma cell line JAR as evidenced by flow cytometry, immunoprecipitation, Western blot and reverse transcriptase polymerase chain reaction analyses. Cross-linking experiments of [125I]-labeled TGF-beta1 to JAR cells indicated that endoglin expressed at the surface of these cells binds TGF-beta. Furthermore, staining of human choriocarcinoma tissue sections with a polyclonal antibody to endoglin demonstrated a high expression of endoglin in syncytiotrophoblast-like areas, as opposed to a negative staining of cytotrophoblast-like cells. This pattern of endoglin expression was confirmed by experiments with methotrexate, an inducer of giant, multinucleated, non-proliferative cells, morphologically indistinguishable from the naturally occurring syncytiotrophoblasts. Thus, treatment of the JAR and JEG-3 choriocarcinoma cell lines with methotrexate led to an increase in endoglin expression, as demonstrated by Western and Northern blot analyses. Taken together, our results suggest that endoglin, in addition to being involved in placental development, may also be a cellular differentiation marker.
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PMID:Endoglin, a component of the TGF-beta receptor system, is a differentiation marker of human choriocarcinoma cells. 959 Jan 31

BeWo is a choriocarcinoma cell line that generates an extracellular matrix (ECM) rich in laminin and is a useful model for human trophoblast. Immunofluorescence with monoclonal antibodies demonstrates that BeWo ECM contains laminin subunits beta1 and gamma1. Immunoprecipitation from conditioned medium shows that the cells secrete two distinct laminin trimers both containing beta1 and gamma1 but with alpha subunits of approx. 400 and 450 kDa. The culture medium also contains a species thought to be beta1 gamma1 dimer. Immunoprecipitation with monoclonal antibody 4C7, previously thought to recognize the alpha1 subunit, isolates complexes containing only the smaller alpha subunit. A second complex containing the larger alpha subunit along with beta1, gamma1 and a 150 kDa polypeptide is precipitated from 4C7-depleted medium with an anti-(laminin 1) polyclonal antibody. Peptide sequencing demonstrates that the 4C7-reactive species is alpha5, which is present as two similarly sized polypeptides. mRNA species encoding laminin subunits alpha1, alpha5, beta1, beta2 and gamma1 are all present in the cells. These results demonstrate the secretion of a novel laminin isoform, laminin 10, the subunit composition of which is alpha5 beta1 gamma1. Laminin 1 is also produced. No evidence for the secretion of beta2-containing laminin isoforms could be derived despite the presence of beta2 mRNA. Analysis with reverse transcriptase-mediated PCR also showed the presence of laminin alpha5 in first-trimester placenta and decidua.
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PMID:BeWo choriocarcinoma cells produce laminin 10. 960 Oct 79


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