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

Analysis of the DNA sequence of the human mu-opioid receptor gene (MOR) revealed that a region overlapping the start codon was substantially homologous to a DNA element named the neurorestrictive suppressor element (NRSE) or restrictive element 1 (RE-1). Transient transfection experiments in the L929 and HEK non-neural cell lines showed that expression of a MOR promoter/reporter gene construct was suppressed in non-neural cell lines by inclusion of this MOR NRSE. Expression from a thymidine kinase promoter was also suppressed when the MOR NRSE was inserted upstream or downstream of the reporter gene. The MOR NRSE did not suppress expression of the reporter gene in neural derived cell lines, IMR-32 and Neuro 2a. The transcription factor REST which binds NRSE thereby enacting the suppression of transcription, was encoded in a plasmid and co-transfected into the IMR-32 cells. The REST co-transfected neuronal derived (IMR-32) cells became sensitive to the MOR NRSE mediated suppression of reporter gene expression. Electrophoretic mobility shift experiments revealed that oligonucleotides containing the MOR NRSE were bound by a factor from nuclear extracts of non-neural cell lines, HeLa and Jurkat. This binding was specifically competed by oligonucleotides containing NRSE sequences previously shown to suppress transcription through REST. Thus an NRSE element overlapping the human MOR start codon suppresses gene expression in non-neural cell lines and may help direct neural tissue specific expression of MOR.
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PMID:Identification of a neurorestrictive suppressor element (NRSE) in the human mu-opioid receptor gene. 1145 94

An iodine-123 labeled bicyclic nucleoside analogue ([(123)I]-4) has been synthesized and evaluated as a potential single photon emission tomography (SPECT) reporter probe for the non-invasive imaging of expression of the varicella zoster virus thymidine kinase (VZV-tk) reporter gene. In vitro enzymatic assays revealed that the non-radioactive mono-iodo derivative 4 has good affinity for VZV-TK (IC(50): 4.2 microM). Biodistribution of [(123)I]-4 was examined in normal mice. Evaluation of [(123)I]-4 in HEK-293T cells showed 1.74-fold higher accumulation in VZV-TK-expressing cells compared to control cells.
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PMID:Synthesis and biological evaluation of an 123I-labeled bicyclic nucleoside analogue (BCNA) as potential SPECT tracer for VZV-tk reporter gene imaging. 1744 73

Tissue-engineered constructs offer a new hope to patients suffering from functional impairment after nerve injury. An effort has been made to focus on delivery, regulation, and "molecular shutoff" of nerve growth factor (NGF) in tissue-engineered constructs. We have previously demonstrated that human embryonic kidney (HEK-293) cells can be genetically modified to secrete NGF at varying time points upon up regulation with Ponasterone A (PonA) both in vitro and in vivo. In the present study, HEK-293 cells that stably and inducibly produce NGF were further stably transfected with herpes simplex virus-thymidine kinase gene as a suicide gene (hNGF-EcR-293-TK) in order to shut off the NGF secretion and kill the cells upon treatment with ganciclovir (GCV). These cells following induction with PonA secreted NGF levels of 6659.2 +/- 489.4 pg/mL at day 10 postbooster dose at day 5, which was significantly higher than the control noninduced cells. The NGF secreted by these cells was bioactive as determined by a rat adrenal pheochromocytoma (PC-12) cell bioassay. Treatment of these cells with GCV significantly reduced the NGF levels to 645.3 +/- 16.2 pg/mL at day 10 and live cell numbers dropped to 7.95 x 10(3) +/- 278 compared to 2.73 x 10(5) +/- 6.1 x 10(4). GCV-treated cell media when transferred to the PC-12 cell bioassay demonstrated less than 10% cells differentiating into neurite-like extensions. We conclude that hNGF-EcR-293-TK cells can inducibly secrete bioactive NGF when treated with the inducing agent and can also be killed upon treatment with GCV. This double-gene transfection for gene expression and molecular shutoff mechanism will be a useful tool in tissue-engineered nerve constructs.
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PMID:Herpes simplex virus-thymidine kinase-based suicide gene therapy as a "molecular switch off" for nerve growth factor production in vitro. 1762 31

The limitations of the ganciclovir (GCV)/herpes simplex virus thymidine kinase (HSV1 TK: EC 2.7.1.21) system as a suicide gene therapy approach have been extensively studied over the years. In our study, we focused on improving the cytotoxic profile of the GCV/equine herpes virus-4 thymidine kinase (EHV4 TK: EC 2.7.1.21) system. Our approach involved the structure-guided mutagenesis of EHV4 TK in order to switch its ability to preferentially phosphorylate the natural substrate deoxythymidine (dT) to that of GCV. We performed steady-state kinetic analysis, genetic complementation in a thymidine kinase-deficient Escherichia coli strain, isothermal titration calorimetry, and analysis of GCV-induced cell killing through generation of HEK 293 stable cell-lines expressing EHV4 TK mutants and wild-type EHV4 TK. We found that the EHV4 TK S144H-GFP mutant preferentially phosphorylates GCV and confers increased GCV-induced cytotoxicity compared to wild-type EHV4 TK.
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PMID:A designed equine herpes thymidine kinase (EHV4 TK) variant improves ganciclovir-induced cell-killing. 2431 33

Uterine leiomyoma (UL) is the most common benign tumor in women of reproductive age. Gene therapy using suicidal genes appears to be a promising approach for UL treatment. One of key factors for success of gene therapy is the right choice of genetic construct carrier. A promising group of non-viral carriers for cell delivery of expression vectors is cationic Cys-flanked peptides which form tight complexes with DNA due to electrostatic interactions and the presence of interpeptide disulfide bonds. The paper reports a comparative study of the physico-chemical, toxic, and transfectional properties of the DNA-peptide complexes obtained by matrix polymerization or oxidative polycondensation of Cys-flanked peptides using the chain growth terminator 2-amino ethanethiol. We have demonstrated the therapeutic effect of the delivery of the pPTK-1 plasmid carrying the herpes simplex virus type 1 (HSV-1) thymidine kinase gene into PANC-1, and HEK-293T cell culture as well as into primary UL cells. It has been shown that the carriers obtained by oxidative polycondensation transform primary UL cells more efficiently than those produced by matrix polymerization. Treatment with ganciclovir resulted in the death of up to 40% of UL cells transfected with the pPTK-1 plasmid. The perspectives of use of the polyR6 carrier produced by oxidative polycondensation as a tool for the development of modular peptide carriers for the purposes of UL gene therapy were discussed.
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PMID:[Cys-Flanked Cationic Peptides For Cell Delivery of the Herpes Simplex Virus Thymidine Kinase Gene for Suicide Gene Therapy of Uterine Leiomyoma]. 3249 14