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:2.7.1.21 (thymidine kinase)
7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Y1 mouse adrenocortical tumor cells, expression of steroid 11 beta-hydroxylase (11 beta-OHase) is stimulated by cAMP following a delay of 4-6 h. Our results demonstrate that a cAMP-responsive element (CRE) within the 11 beta-OHase promoter region is a major determinant of this induction. The 5'-flanking sequences from the mouse 11 beta-OHase gene were placed in front of a human growth hormone reporter gene and transfected into Y1 cells. Treatment of transfected cells with 8-bromo-cAMP increased expression directed by the 11 beta-OHase 5'-flanking region by 3.8-fold. In 5'-deletion analyses, 123 base pairs of 5'-flanking sequences were sufficient for cAMP induction, whereas cAMP treatment did not affect expression of a plasmid with only 40 base pairs of 5'-flanking sequence. Within these 123 base pairs, a region from -56 to -49 matched 7 of 8 bases comprising the consensus sequence for the CRE. 11 beta-OHase 5'-flanking sequences from -65 to -42, including the CRE-like sequence, conferred cAMP inducibility to promoters from the thymidine kinase and chorionic gonadotropin alpha-subunit genes. DNase I footprinting and Southwestern blotting analyses demonstrated that the protein which interacted with the CRE in the 11 beta-OHase promoter region was similar to the CRE-binding protein associated with other cAMP-regulated genes. Together, these results suggest that an interaction between the 11 beta-OHase CRE and CRE-binding protein mediates cAMP induction of the 11 beta-OHase gene.
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PMID:A cAMP-responsive element regulates expression of the mouse steroid 11 beta-hydroxylase gene. 254 79

The upstream regulatory region of the human papilloma virus-16 (HPV-16) genomic DNA contains a sequence element with a large degree of homology to the partially palindromic sequence GGTACANNNTGTTCT, which is the consensus sequence of the glucocorticoid responsive elements of known genes regulated by this steroid hormone. DNase I and dimethylsulfate protection experiments reveal the binding of this sequence by rat glucocorticoid receptor protein. A 400-bp DNA segment centrally containing this sequence confers strong inducibility by dexamethasone to the promoter p97 of HPV-16 and to the Herpes simplex virus thymidine kinase promoter, as judged by chloramphenicol acetyltransferase activity and RNase protection assays. The same DNA segment, that does not contain the consensus sequences of all papilloma viruses relevant for E2 protein-mediated transcription enhancement, functions in an enhancer-like fashion in addition to its glucocorticoid responsive action. This hormone-independent transcription enhancement is absent in human MCF7 cells, but is strong in human HeLa cells where the combined activity of the constitutive and the steroid hormone-dependent enhancer elements stimulate transcription by a factor of 500. This cell type specificity of the HPV-16 enhancer may be responsible for the tissue tropism of the virus. These observations and the presence of numerous homologies to known enhancers of cellular and viral genes suggest a complex pattern of activation of the human papilloma virus-16 promoters.
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PMID:The upstream regulatory region of the human papilloma virus-16 contains an E2 protein-independent enhancer which is specific for cervical carcinoma cells and regulated by glucocorticoid hormones. 282 35

High affinity mouse HMG-I binding sites have been distinguished from other (A+T)-rich sequences using band competition assays. These sites have been found 3' to the coding regions of a variety of genes. For the herpes simplex virus thymidine kinase and minute virus of mice genes, high affinity HMG-1 binding sites were further localized to the functional polyadenylation signal by DNase I footprinting. These results suggest that HMG-I may function at the 3' ends of genes in vivo.
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PMID:Interaction of the mouse chromosomal protein HMG-I with the 3' ends of genes in vitro. 283 77

The chicken vitellogenin II gene is transcriptionally activated by estrogens. In transient transfection experiments in human T47D cells that contain receptors for various steroids, we showed estradiol, progestin, and androgen responses of a chimeric chicken vitellogenin II construct. This construct consists of DNA sequences from -626 to -590 upstream of the start of transcription of the chicken vitellogenin gene linked to the herpes simplex virus thymidine kinase promoter driving the transcription of the bacterial chloramphenicol acetyltransferase gene. Treatment of the transfected T47D cells with a combination of estradiol and the progestin R5020 led to a superinduction of chloramphenicol acetyltransferase activity, showing a synergistic action of these two steroids. This synergism was not observed upon treatment of the transfected cells with estradiol and the androgen dihydrotestosterone. Using point mutations in the vitellogenin gene fragment, we showed in functional and in in vitro DNase I footprinting assays with a purified progesterone receptor that, for the synergistic action of estradiol and R5020 to occur, the progesterone receptor must be bound to the vitellogenin gene fragment. The progesterone receptor-binding site was localized at -610 to -590, close to the consensus sequence (-626 to -613) for estrogen receptor binding and function. We therefore demonstrate here that two different steroid hormones can be functionally synergistic through the interaction of their corresponding receptors with two different binding sites adjacent to one another.
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PMID:Estrogen and progesterone receptor-binding sites on the chicken vitellogenin II gene: synergism of steroid hormone action. 324 57

The human 4F2 cell surface antigen is a 120-kilodalton (kDa) disulfide-linked heterodimer which is composed of an 80- to 90-kDa glycosylated heavy chain (4F2HC) and a 35- to 40-kDa nonglycosylated light chain (4F2LC). 4F2 belongs to a family of inducible cell surface molecules which are involved in T-lymphocyte activation and growth. To better understand the molecular mechanism(s) that controls 4F2HC gene expression in both resting and activated T cells, a 4F2HC human genomic clone was isolated and structurally characterized. The 4F2HC gene spans 8 kilobases of chromosome 11 and is composed of nine exons. The 5' upstream region of the gene displays several properties which are characteristic of housekeeping genes. It is G+C rich and hypomethylated in peripheral blood lymphocyte DNA and contains multiple binding sites for the Sp1 transcription factor while lacking TATA or CCAAT sequences. This region of the gene also displays sequence homologies with several other inducible T-cell genes, including the interleukin-2, interleukin-2 receptor alpha chain, dihydrofolate reductase, thymidine kinase, and transferrin receptor genes. A 255-base-pair fragment of the 4F2HC gene which contains 154 base pairs of the 5' flanking sequence was able to efficiently promote expression of the bacterial chloramphenicol acetyltransferase gene in human Jurkat T cells, indicating that it contains promoter or enhancer (or both) sequences. Analyses of chromatin structure in resting and lectin-activated T cells revealed the presence of stable DNase I-hypersensitive sites within both the 5' flanking and intron 1 regions of the 4F2HC gene. Although the 4F2HC gene displayed many of the structural features characteristic of a constitutively expressed gene, lectin-mediated activation of resting peripheral blood T lymphocytes resulted in a dramatic increase in steady-state levels of 4F2HC mRNA.
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PMID:Isolation and structural characterization of the human 4F2 heavy-chain gene, an inducible gene involved in T-lymphocyte activation. 326 70

We mapped cis-acting regulatory elements in the HLA-DR alpha gene, which encodes the monomorphic subunit of the HLA-DR heterodimer. Genomic fragments of HLA-DR alpha were placed 5' or 3' to the chloramphenicol acetyltransferase reporter gene, the transcription of which was initiated from the Herpes simplex thymidine kinase promoter. In transient expression assays, fragments from the body of the HLA-DR alpha gene were able to increase chloramphenicol acetyltransferase activity in a position-, orientation-, and promoter-independent yet tissue-specific fashion. These HLA-DR alpha cis-acting regulatory elements contain previously identified DNase I-hypersensitive sites and DNA sequences homologous to those found in other eukaryotic transcriptional enhancers.
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PMID:A tissue-specific transcriptional enhancer is found in the body of the HLA-DR alpha gene. 347 84

We characterized the activity of a human hsp70 gene promoter by in vitro transcription. Analysis of 5' deletion and substitution mutants in HeLa nuclear extracts showed that the basal activity of the promoter depends primarily on a CCAAT-box sequence located at -65. A protein factor, CCAAT-box-binding transcription factor (CTF), was isolated from HeLa nuclear extracts and shown to be responsible for stimulation of transcription in a reconstituted in vitro system. DNase I footprinting revealed that CTF interacts with two CCAAT-box elements located at -65 and -147 of the human hsp70 promoter. An additional binding activity, heat shock transcription factor (HSTF), which interacted with the heat shock element, was also identified in HeLa extract fractions. This demonstrates that the promoter of this human hsp70 gene interacts with at least two positive transcriptional activators, CTF, which is required for CCAAT-box-dependent transcription as in other promoters such as those of globin and herpes simplex virus thymidine kinase genes, and HSTF, which is involved in heat inducibility.
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PMID:Two transcriptional activators, CCAAT-box-binding transcription factor and heat shock transcription factor, interact with a human hsp70 gene promoter. 356 11

Chicken glyceraldehyde-3-phosphate dehydrogenase gene (GAPD) and thymidine kinase gene (TK) were co-transfected into mouse LMTK- cells by the calcium phosphate precipitation technique. Four of the eight hypoxanthine/aminopterin/thymidine-containing medium-resistant, TK+ transfectants were shown to produce different amounts of chicken glyceraldehyde-3-phosphate dehydrogenase by zymogram analysis. Subcloning and further analysis revealed that the chicken GAPD was stably inherited and that its enzyme subunits randomly combined with mouse subunits in heterotetramers. Although the contribution of chicken enzyme varied from approximately 30 to approximately 90% of the total glyceraldehyde-3-phosphate dehydrogenase activity with a proportional increase in total activity in the different subclones, it did not appear to affect the expression of mouse endogenous glycolytic enzymes since there was no distinct change in the levels of either mouse glyceraldehyde-3-phosphate dehydrogenase mRNA nor mouse phosphoglycerate kinase enzyme activity. The levels of chicken GAPD copy number, mRNA, and enzyme apparently were generally correlated in the different subclones, suggesting that the chicken GAPD in the mouse cells were expressed constitutively. In situ hybridization revealed that the transfected genes were integrated into mouse chromosomes in one cluster, and the locations of these clusters were different in different clones. Chromatin structure analyses of the chicken GAPD in four different transfectants revealed three DNase I-hypersensitive sites located around 0.2, 2.0, and 3.4 kilobases upstream from the 5' side of the gene. These sites are also present in the same locations in chicken lymphoblastoid cells (Kuo, M. T., Iyer, B., and Schwartz, R. J. (1982) Nucleic Acids Res 10, 4565-4579), indicating the dominant transmission of DNase I-hypersensitive cleavage sites in the transfected gene.
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PMID:The expression and chromatin structure of the chicken glyceraldehyde-3-phosphate dehydrogenase gene in mouse cells. 397 17

Stimulation of in vitro transcription mediated by the upstream element of the adenovirus-2 major late promoter (Ad2MLP) involves its recognition by a specific trans-acting factor present in a HeLa whole-cell extract. DNase I footprinting and dimethylsulfate methylation protection experiments were used to determine, at the nucleotide level, upstream sequences which interact with this transcription factor. The ability of upstream element mutants to bind the transcription factor correlates directly with the efficiency of transcription from the corresponding Ad2ML promoters in vivo and in vitro. Competition footprinting experiments show that the transcription factor, which binds to the upstream element of the Ad2MLP, can also interact, but with a lower affinity, with the upstream elements of the Ad2E2a and rabbit beta-globin promoters, both of which display some sequence homology to the 'interacting' region of the Ad2MLP upstream element. The transcription factor does not, however, interact with the upstream elements of either the Ad2E2L, Ad5E3, SV40 early, herpes virus thymidine kinase or chicken conalbumin promoters.
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PMID:Specific interaction between a transcription factor and the upstream element of the adenovirus-2 major late promoter. 409 88

The DNase I (EC 3.1.21.1) sensitivities of the simian virus 40 (SV40) genome, the pBR322 genome, and the herpes simplex virus type 1 thymidine kinase (HSV-1 tk) gene have been compared in teratocarcinoma-derived stem (12-1) and differentiated (12-1a) cell lines established by transfection of thymidine kinase (ATP:thymidine 5'-phosphotransferase, EC 2.7.1.21)-deficient F9 cells with DNA from a tripartite plasmid genome consisting of the pBR322 genome, the SV40 genome, and the HSV-1 tk gene. HSV-1 tk is present in both stem and differentiated cells; SV40 early proteins are present in differentiated cells but not in stem cells; the pBR322 genome is not expressed in either cell type. The SV40 and pBR322 genomes are more sensitive to DNase I digestion in stem cells than in differentiated cells, reflecting the DNase I-hypersensitivity of total stem-cell chromatin. The HSV-1 tk gene is the least sensitive to DNase I digestion in both cell types.
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PMID:Deoxyribonuclease I sensitivity of plasmid genomes in teratocarcinoma-derived stem and differentiated cells. 627 88


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