Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transgenic mice carrying a cDNA to the polyoma virus middle T (mT) antigen linked to the thymidine kinase promoter were generated to study the consequences of deregulated expression of mT-associated tyrosine kinase activity in a wide variety of tissues. Four independent transgenic founder animals were obtained, from one of which was established a transgenic line. This mouse and all its offspring developed multiple neuroblastomas between 2 and 3 months of age. Expression of the transgene (assayed by tyrosine kinase assay and in situ hybridization) was restricted to the neurons of the central and peripheral nervous tissue, probably because of a positional effect of the transgene integration. Characteristic preneoplastic lesions in the sympathetic ganglia and in the adrenal medulla were identified from which the neuroblastomas originated. The tumors arising in these mice show striking analogies to human neuroblastomas, including the sites of development of the tumors, their histological and ultrastructural appearance, and the expression of diagnostic markers, such as synaptophysin, and high expression of the N-myc oncogene. This animal model thus provides a unique tool for studying growth control in sympathetic neuroblasts and the pathogenesis of neuroblastoma.
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PMID:Sympathetic hyperplasia and neuroblastomas in transgenic mice expressing polyoma middle T antigen. 208 3

Using a neural transplantation model, we have studied the effect of polyoma virus middle T antigen and of the viral src oncogene on the developing rat brain. For this purpose, single-cell suspensions of fetal rat brain were prepared on day 14 of gestation (E14), infected with a replication-defective retroviral vector which carries the middle T oncogene driven by an internal thymidine kinase promoter, and stereotaxically injected into the caudoputamen of adult host rats. With mock-infected donor cells, the transplants developed into an organotypically differentiated population of neurons, astrocytes, oligodendrocytes and other central nervous system cell types and expressed marker proteins of mature neuroectodermal cells, including neuron-specific enolase, synaptophysin, neurofilament protein, glial fibrillary acidic protein and S-100 protein. A high percentage of rats carrying transplants infected with the middle T-encoding vector died within two to six weeks from massive haemorrhage into the transplant. Upon microscopic examination, gross abnormalities of the microvasculature were seen, with formation of large blood-filled spaces lined by a thin layer of proliferating endothelial cells. This effect of middle T was apparently cell type-specific, since the differentiation of neuroectodermal cells within the graft proceeded in a regular fashion. In order to assess further the cell-specificity of the oncogene, analogous experiments were carried out with a retroviral construct in which the middle T cDNA had been replaced by the viral src gene (v-src). Transplants infected with the v-src vector developed astrocytomas, but no vascular abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Tumour induction in fetal brain transplants exposed to the viral oncogenes polyoma middle T and v-src. 280 88

In vivo transplantation of undifferentiated embryonic stem (ES) cells can produce teratomas with uncontrolled cell proliferation. Although ES cells may be attractive candidates for human cell-replacement therapy in the future, the major limitation of its application to the therapy is teratoma formation. In the present study, ES cells containing herpes simplex virus-thymidine kinase (HSV-tk) transgene for a suicide gene expression under the control of the Oct-4 promoter was used for ablation of undifferentiated ES cells, which may produce teratomas, using three-dimensional cell culture system allowing a multilayer cell construct. Selective ablation of undifferentiated ES cells expressing HSV-tk gene under the control of Oct-4 promoter was achieved by ganciclovir treatment. Surviving ES cells after ganciclovir treatment expressed several neuron-associated markers such as synaptophysin, beta-tubulin, vesicular glutamate transporter 1, syntaxin, protein kinase C and glial fibrillary acidic protein (GFAP) but not Oct-4. Coexpression of synaptophysin as a marker of neuronal synapse and GFAP as that of glial fibers in the surviving ES cells revealed finely structured neuronal network. Furthermore, decrease of Ki-67 proliferative index was detected in the surviving ES cells. In conclusion, selective ablation of undifferentiated ES cells by a suicide gene decreases proliferative activity and induces neuron-like differentiation in ES cells.
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PMID:Neuron-like differentiation and selective ablation of undifferentiated embryonic stem cells containing suicide gene with Oct-4 promoter. 1839 36