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

---

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

We previously reported that the type II secreted phospholipase A2 (sPLA2) promoter from positions (-326 to +20) ([-326;+20] promoter) is negatively regulated by two adjacent regulatory elements, C (-210 to -176) and D (-247 to -210). This study examines in greater detail the way in which this negative regulation operates. Successive 5' deletions of the [-326;+20] type II sPLA2 promoter indicated that the region upstream of position -195 inhibits the transcription activity sixfold in HepG2 cells but not in HeLa cells. Although the whole [-326;-176] region decreased the activity of a heterologous thymidine kinase promoter, this effect was orientation and position sensitive. C/EBP beta, C/EBP alpha, and C/EBP delta, which bind to element C, prevented the inhibition of promoter activity. Electrophoretic mobility shift experiments identified the binding of NF1-like proteins to the [-225;-218] site, which overlaps an insulin response-like sequence, 5'-TGTTTTG-3'. This sequence bound a factor which also recognized the promoters of the apolipoproteins C-III and A-II. Substitutions preventing the binding of this factor or the NF1-like proteins did not increase the transcription activity, but substitution in the [-217;-204] sequence blocked the transcription inhibition. This sequence did not bind any double-strand binding factor, but its antisense strand is critical for the binding of single-strand binding proteins to the [-232;-191] region. We therefore suggest that these single-strand binding proteins are involved in the inhibitory mechanism.
...
PMID:C/EBP factor suppression of inhibition of type II secreted phospholipase A2 promoter in HepG2 cells: possible role of single-strand binding proteins. 923 81

Retinyl methyl ether (RME) is known to prevent the development of mammary cancer. However, the mechanism by which RME exerts its anticancer effect is presently unclear. The diverse biological functions of retinoids, the vitamin A derivatives, are mainly mediated by their nuclear receptors, retinoic acid receptors (RARs) and retinoid X receptors (RXRs). RARs and RXRs are ligand-dependent transcriptional factors that either activate gene transcription through their binding to retinoic acid response elements or repress transactivation of genes containing the activator protein 1 (AP-1) binding site. Previous studies demonstrated that RME can modulate transcriptional activity of retinoid receptors on retinoic acid response elements, suggesting that regulation of retinoid receptor activity may mediate the anticancer effect of RME. In this study, we present evidence that RME can down-regulate AP-1 activity induced by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate, insulin, growth factors, and the nuclear proto-oncogenes c-Jun and c-Fos. Transient transfection assays demonstrate that inhibition of AP-1 activity occurs on the human collagenase promoter containing an AP-1 binding site or the thymidine kinase promoter linked with an AP-1 binding site. In HeLa cells, the inhibition is observed when RAR-alpha and/or RXR-alpha but not RAR-beta or RAR-gamma expression vectors are cotransfected, whereas the endogenous retinoid receptors in breast cancer cells T-47D and ZR-75-1 were sufficient to confer the inhibition by RME. Furthermore, using gel retardation assay, we show that 12-O-tetradecanoylphorbol-13-acetate- and epidermal growth factor-induced AP-1 binding activity in breast cancer cells is inhibited by RME. These results suggest that one of the mechanisms by which RME prevents cancer development may be due to the repression of AP-1-responsive genes.
...
PMID:Retinyl methyl ether down-regulates activator protein 1 transcriptional activation in breast cancer cells. 927 11

The mammalian homeobox gene pdx-1 is expressed in pluripotent precursor cells in the dorsal and ventral pancreatic bud and duodenal endoderm, which will produce the pancreas and the rostral duodenum. In the adult, pdr-1 is expressed principally within insulin-secreting pancreatic islet beta cells and cells of the duodenal epithelium. Our objective in this study was to localize sequences within the mouse pdx-1 gene mediating selective expression within the islet. Studies of transgenic mice in which a genomic fragment of the mouse pdx-1 gene from kb -4.5 to +8.2 was used to drive a beta-galactosidase reporter showed that the control sequences sufficient for appropriate developmental and adult specific expression were contained within this region. Three nuclease-hypersensitive sites, located between bp -2560 and -1880 (site 1), bp -1330 and -800 (site 2), and bp -260 and +180 (site 3), were identified within the 5'-flanking region of the endogenous pdx-1 gene. Pancreatic beta-cell-specific expression was shown to be controlled by sequences within site 1 from an analysis of the expression pattern of various pdr-1-herpes simplex virus thymidine kinase promoter expression constructs in transfected beta-cell and non-beta-cell lines. Furthermore, we also established that this region was important in vivo by demonstrating that expression from a site 1-driven beta-galactosidase reporter construct was directed to islet beta-cells in transgenic mice. The activity of the site 1-driven constructs was reduced substantially in beta-cell lines by mutating a hepatocyte nuclear factor 3 (HNF3)-like site located between nucleotides -2007 and -1996. Gel shift analysis indicated that HNF3beta present in islet beta cells binds to this element. Immunohistochemical studies revealed that HNF3beta was present within the nuclei of almost all islet beta cells and subsets of pancreatic acinar cells. Together, these results suggest that HNF3beta, a key regulator of endodermal cell lineage development, plays an essential role in the cell-type-specific transcription of the pdx-1 gene in the pancreas.
...
PMID:Hepatocyte nuclear factor 3beta is involved in pancreatic beta-cell-specific transcription of the pdx-1 gene. 931 59

Insulin stimulates cellular oncogenic activators such as c-jun, c-fos, and c-myc; and hepatitis B virus (HBV) X, a viral transactivator, is known to induce liver cancer in transgenic mice. In this respect, the effect of insulin on the expression of HBx protein was investigated in HepG2 cells. Insulin-stimulated transcription from the HBV X promoter in a dose-dependent manner was assessed by chloramphenicol acetyltransferase (CAT) assay. A mutation preventing AP-1 binding to the E element abolished the activation of the HBV X promoter by insulin. In addition, insulin stimulated the minimal thymidine kinase (tk) gene promoter activity through both the HBV E element and the consensus AP-1 binding site in HepG2 cells. An electrophoretic mobility shift assay (EMSA) using insulin-treated HepG2 nuclear extracts showed that insulin actually enhanced the binding of nuclear proteins to the HBV E element as well as to the consensus AP-1 binding site. Both HBV E and AP-1 oligonucleotides were effective competitors for this binding. These results showed that insulin elevated the expression of HBx protein through the AP-1 binding site of HBV EnI. We suggest that insulin can augment the role of HBx in the development of hepatocellular carcinoma (HCC) in HBV-infected liver, probably through interaction with other cellular oncogenes.
...
PMID:Insulin activates the hepatitis B virus X gene through the activating protein-1 binding site in HepG2 cells. 983 4

Confluent 3T3-L1 preadipocytes differentiate to adipocytes in the presence of insulin, dexamethasone, and isobutylmethylxanthine (IDI). A transient increase of DNA synthesis is induced in 3T3-L1 cells 18 h after addition of IDI, followed by an arrest in the G1 phase of the cell cycle. Growth arrested cells express the proto-oncogene c-myc and the gene for the CCAAT/enhancer binding protein (C/EBPalpha) between day 2 and 5. While c-Myc is strongly implicated in cell proliferation, C/EBPalpha: is a differentiation-specific transcription factor with antiproliferative activity. Here we have characterized the cell cycle arrest in differentiating 3T3-L1 cells. Arrested cells express the Cdk inhibitors p21 and p27, but, at the same time, show hyperphosphorylation of Rb and expression of the E2F-regulated thymidine kinase gene. The addition of new serum to arrested cells resulted in cyclin A expression and Cdk2 activity, but not in DNA synthesis. Simian virus 40 large tumor antigen (LTAg) is a potent mitogen. The mutant LTAg-K1, deficient in binding of pocket proteins and unable to induce DNA synthesis in serum-starved 3T3-L1 cells, efficiently induced DNA synthesis in differentiating 3T3-L1 cells. This indicates that pocket proteins are probably not involved in the control of the cell cycle arrest during 3T3-L1 cell differentiation. Our data suggest that the differentiation-specific cell cycle block in 3T3-L1 cells is resistant to high levels of c-Myc, inactivation of pocket proteins, upregulation of cyclin A levels, and Cdk2 activation, but can be abolished by a function of LTAg that is independent of binding to pocket proteins.
...
PMID:Analysis of cell cycle arrest in adipocyte differentiation. 992 2

Glucose-dependent insulinotropic polypeptide (GIP) plays an important role in stimulating insulin release in the pancreas as well as inhibiting gastric acid secretion in the stomach. GIP has been found in specific endocrine cells located in the mucosal layer of the small intestine and in the submandibular salivary gland. In this study, the tissue-specific expression of GIP guided by 1.2 kb of the human GIP (hGIP) gene 5' flanking region was investigated by a transgenic mouse approach. A chimeric promoter-reporter gene construct linking the 5'-flanking region of the hGIP gene with the thymidine kinase gene of the herpes simplex virus was introduced into the genomes of mice by microinjection. By reverse transcriptase-PCR (RT-PCR) and thymidine kinase assays, transgene expression was found in the stomach and pancreas. The enzyme activity detected in the stomach was about 6-fold higher than that found in the pancreas, suggesting that GIP may be expressed in the stomach. This observation is supported by RT-PCR studies since both human and mouse GIP transcripts are detected in the stomach and small intestine. In addition, distinct GIP-producing cells were identified in both tissues in mouse by in situ hybridization and immunohistochemical staining. Taken together, our data demonstrate for the first time that GIP is expressed in human and mouse stomach.
...
PMID:Glucose-dependent insulinotropic polypeptide gene expression in the stomach: revealed by a transgenic mouse study, in situ hybridization and immunohistochemical staining. 1050 10

Using a human growth hormone reporter system, the introduced mutations in GG1 alone or both GG elements of GG1 and GG2 in the human insulin promoter abolished 94 or 96% of the beta-cell-specific transcriptional activity in a pancreatic islet beta-cell line of MIN6, while the mutations in GG2 or its total deletion abolished 85 or 86% of the transcriptional activity. When linked to the thymidine kinase promoter, mutations in GG1 or both GG elements abolished 74% of the transcriptional activity in MIN6 cells, while the mutations in GG2 or its total deletion abolished 55 or 54%. In the electrophoretic mobility shift assay (EMSA), one nuclear factor was shown to interact with two GG elements, and another C1-binding factor with GG1 and C1. The differential effects of deletions or selective mutations in the GG2 or GG1 sequence in the oligonucleotide probes on the binding activity of GG- or C1-binding factors in EMSA proved the requirement of both GG1 and GG2 or both GG1 and C1, respectively, for the transaction of these two factors. The molecular size of the GG-binding factor was estimated about 30 kDa. Based on these, we conclude that two GG elements contribute, with GG1 more critically than GG2, to the beta-cell-specific transcription of the human insulin gene through transaction with the GG- and C1-binding factors.
...
PMID:Differential regulation of the human insulin gene transcription by GG1 and GG2 elements with GG- and C1-binding factors. 1052 98

Expression of the rat cytosolic aspartate aminotransferase gene is stimulated by glucocorticoids and repressed by insulin in the liver. The regulation by insulin and part of the glucocorticoid effect are mediated by a distal region in the promoter. A 142 bp fragment (-1844 to -1702) confers hormonal sensitivity to the heterologous thymidine kinase promoter in transient-transfection assays in H4IIEC3 hepatoma cells. Footprinting and gel-shift assays showed that several nuclear proteins bind to this region at conserved CCAAT-enhancer binding protein (C/EBP), activator protein (AP-1) and E-box sequences. Hepatocyte nuclear factor-3alpha (HNF-3)alpha and beta bind to sequences upstream of a glucocorticoid-responsive element (GRE) half-site as demonstrated by supershift experiments. Nuclear factor I (NFI)-like proteins bind downstream of the GRE half-site. These sites around the GRE motif overlap with five insulin responsive element (IRE) -like sequences (TG/ATTT). The effect of insulin was not prevented by any single mutation in the IRE-like sites. However, mutation of two IRE sites (namely IREc and d) prevented the insulin effect although only marginally affecting the glucocorticoid effect. The results suggest that the effect of insulin is due to a complex interplay of factors requiring the synergistic contribution of at least two sites and underline the contribution of HNF-3 and NFI-like proteins.
...
PMID:Delineation of the insulin-responsive sequence in the rat cytosolic aspartate aminotransferase gene: binding sites for hepatocyte nuclear factor-3 and nuclear factor I. 1052 50

The extracellular matrix-associated glycoprotein secreted protein acidic and rich in cysteine (SPARC) has been implicated in the control of cell proliferation during tissue remodeling, wound healing, and malignant development. Here, we describe a novel mechanism through which SPARC influences cell cycle progression in embryonic fibroblasts derived from Sparc-nullizygous (-/-) mice. SPARC-deficient cells were indistinguishable from wild-type cells in their ability to initiate DNA synthesis after treatment with either fetal bovine serum or platelet-derived growth factor. In contrast, Sparc -/- cells responded poorly to activation of the insulin-like growth factor receptor (IGFI-R) by insulin. This defect was traced to reduced expression of the IGFI-R in Sparc -/- cells. Consistent with impaired cell cycle progression through S-phase, insulin-stimulated Sparc -/- cells also revealed reduced expression of two key regulators of S phase progression (cyclin A and thymidine kinase), whereas expression of the G1 phase progression regulators cmyc or cyclin D1 was unaffected. An examination of the status of retinoblastoma family pocket proteins in Sparc -/- cells revealed a selective and dramatic reduction in levels of the retinoblastoma-related protein p107. Exogenous platelet-derived growth factor restored expression of the IGFI-R and IGFI-R dependent DNA synthesis as well as induction of cyclin A, thymidine kinase, and p107 in insulin-stimulated Sparc -/- cells. These results suggest that SPARC-dependent matrix to cell interactions contribute to the regulation of p107 and cyclin A through IGFI-R dependent pathway(s).
...
PMID:Loss of insulin-like growth factor I receptor-dependent expression of p107 and cyclin A in cells that lack the extracellular matrix protein secreted protein acidic and rich in cysteine. 1059 48

The omega-agatoxin-IVA-sensitive P/Q-type Ca(2+) channel plays a role in insulin release from the pancreatic islets of beta cells. To dissect the molecular mechanisms underlying beta cell expression of the P/Q-type channel, we characterized the 5'-upstream region of the mouse alpha(1A) subunit gene using transgenic mice and HIT insulinoma cells. The E. coli lacZ reporter gene was expressed in pancreatic acini and islets in transgenic mice carrying the 6.3 kb or 3.0 kb of the 5'-upstream region, although those with 1.5 kb or 0. 5 kb of the 5'-upstream region failed to show reporter expression on histological examination. As the expression of alpha(1A)subunit gene could not be detected in acini using RT-PCR analysis, the reporter expression in acini might have been ectopic expression. When linked to the placental alkaline phosphatase reporter gene to examine promoter activity for beta cell expression, the 6.3 kb and 3.0 kb fragment of the 5'-upstream region, but not the smaller 1.5 kb fragment, were able to drive reporter gene expression in HIT cells. The sequence between 3.0 and 1.5 kb upstream of the start codon enhanced thymidine kinase promoter activity in HIT cells, but not in fibroblast NIH3T3 cells. These results suggested that the beta cell-specific elements of the alpha(1A) subunit gene are likely to be located in the distal upstream region (-3021 to-1563) of the 5'-upstream sequence and that the 6.3 kb fragment of the 5'-upstream region alone might be a lack of a negative cis-regulatory element(s) to suppress the alpha(1A) subunit gene expression in acini.
...
PMID:Analysis of the 5'-upstream region of mouse P/Q-type Ca2+ channel alpha1A subunit gene for expression in pancreatic islet beta cells using transgenic mice and HIT-T15 cells. 1075 23


<< Previous 1 2 3 4 5 6 7 Next >>

---