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)

Neurons have evolved strategies to evade immune surveillance that include an inability to synthesize the heavy chain of the class I major histocompatibility complex (MHC), proteins that are necessary for cytotoxic T lymphocyte (CTL) recognition of target cells. Multiple viruses have taken advantage of the lack of CTL-mediated recognition and killing of neurons by establishing persistent neuronal infections and thereby escaping attack by antiviral CTL. We have expressed a class I MHC molecule (Db) in neurons of transgenic mice using the neuron-specific enolase (NSE) promoter to determine the pathogenic consequences of CTL recognition of virally infected, MHC-expressing central nervous system (CNS) neurons. The NSE-Db transgene was expressed in H-2b founder mice, and transgene-derived messenger RNA was detected by reverse transcriptase-polymerase chain reaction in transgenic brains from several lines. Purified primary neurons from transgenic but not from nontransgenic mice adhered to coverslips coated with a conformation-dependent monoclonal antibody directed against the Dv molecule and presented viral peptide to CTL in an MHC-restricted manner, indicating that the Db molecule was expressed on transgenic neurons in a functional form. Transgenic mice infected with the neurotropic lymphocytic choriomeningitis virus (LCMV) and given anti-LCMV, MHC-restricted CTL displayed a high morbidity and mortality when compared with controls receiving MHC-mismatched CTL or expressing alternative transgenes. After CTL transfer, transgenic brains showed an increased number of CD8+ cells compared with nontransgenic controls as well as an increased rate of clearance of infectious virus from the CNS. Additionally, an increase in blood-brain barrier permeability was detected during viral clearance in NSE-Db transgenic mice and lasted several months after clearance of virus from neurons. In contrast, LCMV-infected, nontransgenic littermates and mice expressing other gene products from the NSE promoter showed no CNS disease, no increased intraparenchymal CTL, and no blood-brain barrier damage after the adoptive transfer of antiviral CTL. Our study indicates that viral infections and CTL-CNS interactions may induce blood-brain barrier disruptions and neurologic disease by a "hit-and-run" mechanism, triggering a cascade of pathogenic events that proceeds in the absence of continual viral stimulation.
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PMID:Consequences of cytotoxic T lymphocyte interaction with major histocompatibility complex class I-expressing neurons in vivo. 759 91

The precursor cells that form the enteric nervous system (ENS) are multipotent when they arrive in the gut from the neural crest. Their differentiation thus depends on signals from the enteric microenvironment. Crest-derived cells were isolated from the fetal rat bowel by immunoselection at E14 with NC-1/HNK-1 antibodies and secondary antibodies coupled to magnetic beads. NC-1/HNK-1-immunoreactive cells were enriched approximately 36-fold. The NC-1/HNK-1-selected population and the residual population were plated at equal cell density and maintained in a defined medium for 6-7 d. The total number of cells found in the cultures of the residual cells was three- to fourfold that in cultures of immunoselected cells. Neurotrophin-3 (NT-3), but not nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), or neurotrophin-4/5 (NT-4/5), was found to increase the proportion of neurons (neurofilament-immunoreactive or neuron-specific enolase-immunoreactive) or glia (S-100-immunoreactive) (from 6.6 +/- 0.9% to 15.2 +/- 1.4%; p < 0.001). This effect was concentration dependent (from 1 to 40 ng/ml) and observed only in the cultures of immunoselected cells. NT-3 also enhanced neurite outgrowth. NT-3 increased neither cell number nor bromodeoxyuridine incorporation and thus was not mitogenic. Exposure of immunoselected cells to NT-3 rapidly and transiently induced the appearance of nuclear Fos immunoreactivity. Transcripts coding for TrkC, the transducing receptor for NT-3, were identified in the fetal rat gut (E14-E16) and in the immunoselected population of cells using reverse transcriptase and the polymerase chain reaction. It is concluded that NT-3 specifically promotes the differentiation of enteric crest-derived cells as neurons or glia and may thus play a role in the development and/or maintenance of the ENS.
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PMID:Neurotrophin-3 induces neural crest-derived cells from fetal rat gut to develop in vitro as neurons or glia. 796 61

The presence of t(11;22)(q24;q12) is often considered diagnostic of Ewing sarcoma and peripheral primitive neuroectodermal tumor (pPNET). We report a case of a polyphenotypic tumor that possessed this translocation as detected by reverse transcriptase polymerase chain reaction (RT-PCR). This tumor was positive for vimentin, desmin, low-molecular-weight keratin, neuron-specific enolase, S-100 protein, and CD57 by immunohistochemistry. Of note, the tumor was negative for MIC2. The tumor had double-minute chromosomes with > 100 copies of the MDM2 gene. Thus, the presence of the t(11;22)(q24;q12) translocation should not be considered diagnostic of Ewing sarcoma and pPNET in the absence of supporting histologic evidence such as positive staining for MIC2. The presence of this translocation in Ewing sarcoma and pPNET has been taken as evidence that these two tumors are related. Rather than extending this relationship to include some polyphenotypic tumors, other tumors may acquire this genetic change during tumor progression. Treatment regimens for tumors may be better based on phenotype rather than genotype when these two profiles are seemingly in conflict.
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PMID:Intra-abdominal polyphenotypic tumor. 896 28

Peripheral primitive neuroectodermal tumour (pPNET or peripheral neuroepithelioma) is one of the malignant small round cell tumours of peripheral nerves, soft tissues and bones, but rarely originates in the spinal canal. We report an example of pPNET arising in the cauda equina of a 14-year-old Japanese boy. At surgery, a well-demarcated tumour measuring 2 x 4 cm in diameter and involving one of the nerve roots of the cauda equina was located within the intradural space with no evidence of extradural extension. Microscopically the tumour was made up of sheets of closely packed small round cells, associated with ganglioneuroma-like islands. Immunohistochemically, the small round tumour cells were intensely positive for neuron-specific enolase (NSE), an MIC2 gene product (O13) and beta 2-microglobulin, whereas the foci with ganglion cell-like cells reacted positively to NSE, synaptophysin and beta 2-microglobulin but were negative for O13. A chimeric transcript of the EWS/FLI-1 fusion gene detected by a nested reverse transcriptase-polymerase chain reaction using formalin-fixed paraffin-embedded tissue justified the diagnosis of pPNET. Only 6 cases of PNET in the cauda equina have been described in the literature, and this is the first case of a pPNET with ganglio-neuroma-like areas. This finding suggests that the primitive tumour cells of pPNET may respond to unknown inductive effects and express a ganglion cell-like morphology.
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PMID:Peripheral primitive neuroectodermal tumour with ganglioneuroma-like areas arising in the cauda equina. 946 79

Evidence for the existence of neuroendocrine (NE) differentiation in non-small cell lung carcinomas (NSCLCs) is at present based on histochemical, ultrastructural, and immunohistochemical data. The aim of this study was to investigate the extent of NE differentiation in NSCLCs as revealed by mRNA analysis. Different techniques including immunohistochemistry (IHC), northern blot analysis (NBA), and reverse transcriptase-polymerase chain reaction (RT-PCR) were employed in parallel to reveal the panendocrine marker chromogranin A (CgA). The data were related to pathological, immunocytochemical (PGP 9.5, synaptophysin, Leu-7 and neuron-specific enolase), and prognostic indicators. Forty surgically resected cases of NSCLC (24 squamous cell carcinomas, 12 ordinary type adenocarcinomas, 3 bronchiolo-alveolar carcinomas, and 1 anaplastic large cell carcinoma), in which fresh frozen material was available for mRNA analysis, were collected. CgA immunoreactivity was present in five cases (12.5 per cent), generally confined to a minority of the neoplastic cell population. By RT-PCR, CgA mRNA was found in 20 cases (50 per cent), including the five tumours positive by IHC. A statistically significant correlation was found between the two techniques. By NBA, no CgA mRNA expression was detected. Leu-7 immunoreactivity was present in 15 per cent of cases, NSE in 52.5 per cent, synaptophysin in 10 per cent, and PGP 9.5 in 82.5 per cent. In NSCLC, no correlations were found between CgA production, as detected by IHC or RT-PCR methods, and the histological type, stage, grade and proliferative activity of tumours, or the disease-free interval. It is concluded that CgA gene expression can be revealed in NSCLC at both mRNA and protein levels and that RT-PCR is a valuable tool for identifying NE differentiated NSCLCs. Our data suggest that NE differentiation does not represent an independent prognostic factor in surgically resected NSCLCs.
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PMID:Chromogranin A gene expression in non-small cell lung carcinomas. 992 30

Copper zinc superoxide dismutase (CuZnSOD) is an important enzyme for the detoxification of reactive oxygen species. Particularly in the central nervous system (CNS), reactive oxygen species are often associated with acute brain injuries and chronic neurodegeneration. It has been demonstrated in vivo that there is an inverse correlation between CuZnSOD activity and neuronal death after acute brain injury. To further understand the protective role of CuZnSOD upon neurons, we have generated transgenic mouse lines with targeted expression of the human CuZnSOD gene (SOD1) that is driven by a rat neuron-specific enolase gene promoter in neurons of the CNS. The transgenic SOD1 expression was restricted to the CNS identified by reverse transcriptase polymerase chain reaction and SOD gel electrophoresis assays. The CuZnSOD activity was significantly increased in the brain stem of the transgenic mice. Immunostaining of human CuZnSOD activity showed that Purkinje cells in the cerebellar cortex were the most intensely stained neurons in the CNS of the transgenic mice.
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PMID:Targeted expression of human CuZn superoxide dismutase gene in mouse central nervous system. 1047 83

Primitive neuroectodermal tumor (PNET) is a small round cell sarcoma that mainly develops in the central nervous system and soft tissues of childhood; however recently, primary occurrence of this tumor in the kidney has been reported. We experienced one case of PNET primarily arose in the kidney without metastasis. The patient was a 28-year-old man whose chief complaint was abdominal pain, especially on exercise. On computed tomography scan and magnetic resonance imaging, a solid lesion was found in the left kidney, and a left nephrectomy was performed based on the diagnosis of a tumor in the left kidney. The tumor was within the parenchyma of lower end of left kidney protruding into the abdominal cavity. Histologically, diffuse proliferation of primitive small round cells with rosette formation was found. Immunohistochemically, MIC2 gene product, neuron-specific enolase and S-100 protein were positive. No metastasis to the regional lymph nodes was found. From these observations, the tumor was diagnosed as PNET primarily arising in the left kidney. Although chromosome analysis was not performed, EWS-FLI1 chimera gene was identified by reverse transcriptase-polymerase chain reaction on the freshly frozen specimen and fluorescence in situ hybridization on paraffin sections.
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PMID:Primary primitive neuroectodermal tumor of the kidney. 1112 63

Central nervous system (CNS) stem cells require epidermal growth factor (EGF) to survive and express glial-specific proteins (GSPs) under its influence. EGF and its receptor (EGF-R) therefore are involved in gliogenesis. We hypothesize that EGF selectively modulates GSP expression in pluripotential CNS cells and this effect is dependent on the degree of EGF-R activation (i.e., the amount of both EGF and the EGF-R present). In order to explore this, we investigated the effects of EGF on the expression of glial- and neuronal-specific proteins in the pluripotential human neuroectodermal cell line, DAOY. DAOY clones expressing different EGF-R levels were treated with EGF. The expression of glial fibrillary acid protein (GFAP), glutamine synthetase (GS) and neuron-specific enolase (NSE) were measured by ELISA. In a clone with low EGF-R levels (clone DAOY-YS-15), EGF selectively stimulated GSPs. In cells which express twice the EGF-R level, EGF (10(-8) M) stimulated both glial and neuronal proteins nonspecifically. In cells with higher EGF-R numbers, EGF suppressed both glial and neuronal proteins. These effects were not due to the negligible growth influences of EGF on the cells. In clone DAOY-YS-15, selective GSP expression was observed as early as 2 days after exposure to EGF (10(-9) M). In these cells, GFAP induction was also shown at the transcriptional level using a quantitative reverse transcriptase-polymerase chain reaction. This suggests one mechanism for EGF action. Our findings are therefore consistent with the hypothesis that the selective induction of GSPs in pluripotent cells is dependent on the EGF-R level and the degree of EGF-R activation.
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PMID:Stimulation of the epidermal growth factor receptor induces glial-specific protein expression in the human DAOY neuroectodermal cell line. 1117 30

The primary neuroendocrine carcinoma of the skin or Merkel cell carcinoma (MCC) is a skin tumor with aggressive biological behaviour. Experimental models for investigating the biological properties of the tumor are prerequisite for developing new therapeutic approaches. In this study, we report the establishment and characterisation of a cell line derived from the lymph-node metastasis of a patient with highly aggressive MCC. Merkel carcinoma cells (MCC-1) grew as floating aggregates in suspension cultures for more than two years and over 70 subcultures. The proliferation rate in suspension cultures was rather moderate with a population doubling time of 69 h. The immunocytochemical pattern of the cultured MCC-1 was similar to that of the original tumor with expression of cytokeratin 18, neuron-specific enolase, neurofilaments, and synaptophysin. In addition, reverse transcriptase polymerase chain reaction (RT-PCR) revealed presence of chromogranin A mRNA in the MCC-1 cell line. Furthermore, electron microscopy yielded the rare finding of neuroendocrine granules in the cytoplasm of the cultured cells. The cell line MCC-1 was able to form colonies in soft agar. Nude mice developed solid tumors with similar histology to the original tumor after subcutaneous and intravenous injections of cultured MCC-1, and malignant ascites was seen after intraperitoneal injection. Also, two MCC-1 sublines were established by reculturing cells from the xenografts grown in vivo and immunocytochemistry confirmed their neuroendocrine origin. The MCC-1 line may thus serve as a model for studying the biology and the metastatic potential of Merkel cell carcinoma.
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PMID:Growth and characterization of a cell line from a human primary neuroendocrine carcinoma of the skin (Merkel cell carcinoma) in culture and as xenograft. 1131 62

Three (propositus) cases of basal cell carcinoma (BCC) showing endocrine differentiation at the immunohistochemical level were studied using reverse transcriptase-polymerase chain reaction (RT-PCR) to determine the presence of mRNA of chromogranin A. Moreover, 20 (consecutive) cases of BCC were studied with immunohistochemistry alone using chromogranin A, synaptophysin, S100 protein, cytokeratin 20, and neuron-specific enolase antibodies (NSE). The three propositus cases of BCC showed positive results when RT-PCR for mRNA of chromogranin A was performed. Eleven out of 20 consecutive cases of BCC were focally positive for chromogranin A antibody. These results confirm the presence of endocrine differentiation in BCC, demonstrated both with immunohistochemistry and with RT-PCR.
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PMID:[Endocrine differentiation in basocellular carcinoma]. 1143 14


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