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)

The herpes simplex virus genome consists of at least three groups of genes--alpha, beta, and gamma--whose expression is coordinately regulated and sequentially ordered in a cascade fashion. We have established that the elements involved in regulation of alpha genes are a sequence that promotes gene expression and a sequence that confers alpha regulation on the gene by responding to trans-acting regulatory signals. The domains of these sequences were mapped by determining the regulation of thymidine kinase (TK) in L cells converted to TK+ phenotype by chimeric TK indicator genes. The chimeric genes were constructed from appropriate portions of the TK gene fused to donor sequences derived from the 5' nontranscribed and nontranslated leader portions of the viral alpha gene 4. The results were as follows. (i) The natural beta TK indicator extending 5' up to -80 and the chimeric alpha TK extending 5' up to -110 both converted cells to TK+ phenotype but were not regulated. (ii) A segment of the regulator region of the alpha gene 4, extending 5' from position -110, confers inducible alpha-type regulation when fused to the nonregulated but expressible beta TK indicator described above. (iii) The extent of gene induction appears to hinge on the size of the regulatory region inserted into the chimeric gene and correlates with the presence of repeated consensus sequences and G+C-rich inverted repeats in the regulatory region of the alpha gene 4 and other alpha genes.
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PMID:Differentiation between alpha promoter and regulator regions of herpes simplex virus 1: the functional domains and sequence of a movable alpha regulator. 628 23

Previous studies have shown that herpes simplex virus genes form three groups, alpha, beta, and gamma, whose expression is coordinately regulated and sequentially ordered in a cascade fashion. Chimeric genes constructed by fusion of the coding and 5' nontranslated leader sequences of the thymidine kinase (TK) gene to the sequences upstream from the site of initiation of transcription of alpha genes 4 and 27 are regulated as alpha genes and are induced in cells converted to TK+ phenotype by infection with TK- virus. In alpha gene 4 (S. Mackem and B. Roizman, Proc. Natl. Acad. Sci. U.S.A. 79:4917-4921, 1982), both the promoter and the regulatory region are separable and movable. The promoter permits expression but not induction when fused to TK in the noncoding leader region of the gene. The regulator, when fused to the promoter of an expressible but noninducible portion of the natural beta TK, renders the gene inducible as an alpha gene; it consists of multiple regulatory units acting cumulatively. In this paper, we report on the precise site of initiation of transcription of alpha gene 0 within the inverted b sequences of the L component of viral DNA. We also report the following. (i) The chimeric gene consisting of the coding and 5' nontranslated leader regions of the TK gene fused to portions of the domain of alpha gene 0 extending largely upstream from the site of initiation of transcription of alpha gene 0 was regulated in the same fashion as the alpha 4- and alpha 27-TK chimeras. The regulatory region in the alpha gene 0 is largely upstream from nucleotide - 140. (ii) The promoter-regulatory regions of alpha genes 0, 4, and 27 share TATA sequences, A + T-rich (consensus) sequences occurring in regulating regions of alpha genes 0 and 4 in more than one copy, and multiple G + C-rich inverted repeats. The relation of these sequences to the function of the promoter-regulatory regions of the alpha genes is discussed.
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PMID:Structural features of the herpes simplex virus alpha gene 4, 0, and 27 promoter-regulatory sequences which confer alpha regulation on chimeric thymidine kinase genes. 629 41

Herpes simplex virus (HSV) genes form three groups, alpha, beta, and gamma, whose synthesis is coordinately regulated and sequentially ordered in a cascade fashion. Earlier studies by Post et al. (Cell 24:555-565, 1981) have shown that chimeric genes constructed by fusion of 5' noncoding leader and upstream sequences of alpha genes to the 5' noncoding leader and structural sequences of the viral thymidine kinase (TK), a beta gene, are regulated as alpha genes upon recombination into the viral genome. In cells converted from TK- to TK+ phenotype, these chimeric genes are induced by infection with homologous TK- virus. The induction of the resident chimeric gene does not require viral protein synthesis and is independent of the presence of functional alpha gene 4 product required for the expression of beta genes. In this paper, we report on the properties of the alpha-TK gene chimera resident in converted TK+ murine (L316) and human (I316) cells. Our results were as follows. (i) The pattern of induction of L316 cells exposed to 0.1, 1.0, and 10 PFU per cell suggested that exposure to competent virus is required for induction and that in untreated preparations this virus corresponds to infectious virus. (ii) UV light-irradiated virus was just as effective as untreated virus in inducing alpha-TK chimeras. (iii) HSV-1(HFEM)tsB7 induced the alpha-TK gene chimeras at the nonpermissive (39 degrees C) temperature; at 39 degrees C the parental HSV-1(HFEM)tsB7 capsids accumulate at nuclear pores and do not release viral DNA. (iv) The alpha-TK gene chimeras were not induced by infection with spontaneous TK- mutants of pseudorabies virus and bovine mammillitis virus or with human cytomegalovirus or adenovirus type 2 or by exposure to lysates of HSV-1-infected cells from which the virus was removed by centrifugation. These results indicate that the alpha gene inducer is a virion component located outside the capsid and that its function might be to stimulate the transcription of alpha genes by recognizing regulatory sites on viral DNAs or host cell products or both.
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PMID:Characterization of the herpes simplex virion-associated factor responsible for the induction of alpha genes. 630 8

The genes of herpes simplex virus 1 form three major groups--alpha, beta, and gamma--whose expression is coordinately regulated and sequentially ordered in a cascade fashion. To determine how the infected cell differentiates between these gene groups, alpha-regulated chimeric genes were constructed in earlier studies by fusing the structural sequences of the thymidine kinase (TK) gene, a beta gene, to the 5' noncoding sequences of alpha genes. These studies showed that (i) one or more structural components of the virion act in trans to increase alpha gene expression and (ii) the 5' noncoding sequences of alpha genes contain cis-acting domains that promote gene expression and confer alpha-gene regulation. These two domains could be moved independently, but the regulatory domain required a promoter for its function. We report here the properties of three sequences containing features common to the regulatory regions of all alpha genes. Sequence 1, containing (G + C)-rich inverted repeats, increased the basal level of TK expression when fused 5' to either the alpha gene 4 promoter or the truncated beta TK promoter. The effect was to some extent orientation dependent. Moreover, sequence 1 restored beta regulation to the truncated beta TK promoter but did not confer alpha-specific regulation on any of the chimeric genes tested. Sequences 2 (49 base pairs) and 3 (29 base pairs), containing an (A + T)-rich homolog from alpha gene 27 and alpha gene 0, respectively, restored alpha-specific regulation to the alpha promoter gene but only sequence 2 conferred alpha regulation on the truncated beta promoter gene. Our results indicate that (i) in natural beta TK the promoter and regulatory domains overlap, (ii) sequence 1 determines basal level of expression and substitutes for a promoter component that is essential for beta but not alpha regulation, and (iii) conversion of a gene with a promoter into an alpha gene requires two elements. Sequence 2 may contain both whereas sequence 3 contains only one.
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PMID:Separation of sequences defining basal expression from those conferring alpha gene recognition within the regulatory domains of herpes simplex virus 1 alpha genes. 633 Jul 37

Herpes simplex virus thymidine kinase (HSV tk) gene therapy combined with ganciclovir (GCV) medication is a potential new method for the treatment of malignant glioma. We have used both retrovirus-packaging cells (PA317/tk) and adenoviruses (Adv/tk) for gene therapy for malignant glioma. Retrovirus-packaging cells were used for eight tumors in seven patients and adenoviruses were used for seven tumors in seven patients. As a control group, seven tumors in seven patients were transduced with lacZ marker gene 4-5 days before tumor resection. Safety and efficacy of the gene therapy were studied with clinical evaluation, blood and urine samples, MRI follow-up, and survival of the patients. Four patients with adenovirus injections had a significant increase in anti-adenovirus antibodies and two of them had a short-term fever reaction. Frequency of epileptic seizures increased in two patients. No other adverse events possibly related to gene therapy were detected. In the retrovirus group, all treated gliomas showed progression by MRI at the 3-month time point, whereas three of the seven patients treated with Adv/tk remained stable (p < 0.05). Mean survival times for retrovirus, adenovirus, and control groups were 7.4, 15.0, and 8. 3 months, respectively. The difference in the survival times between the adenovirus and retrovirus groups was significant (p < 0.012). It is concluded that HSV tk gene therapy is safe and well tolerated. On the basis of these results further trials are justified, especially with adenovirus vectors.
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PMID:Thymidine kinase gene therapy for human malignant glioma, using replication-deficient retroviruses or adenoviruses. 1108 77