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)

The pathologic picture in ischemic tissue injury shares features with the inflammatory response, including production of proinflammatory cytokines. Hypoxia-mediated induction of interleukin-6 (IL-6), a cytokine with anti-inflammatory properties, could set in motion mechanisms limiting inflammation in ischemia. Exposure of cultured endothelial cells (ECs) to H (pO2 approximately 12-16 torr) increased transcription of IL-6, elevated levels of IL-6 mRNA, and induced elaboration of IL-6 antigen in a time-dependent manner. Exposure of mice to hypoxia increased IL-6 transcripts in the lung, and immunostaining revealed a striking increase in IL-6 antigen in pulmonary vasculature. Transfection of ECs with deletion chimeric IL-6 promoter-chloramphenicol acetyl-transferase (CAT) constructs showed hypoxia-mediated 9-11-fold induction with -1200/+13, -596/+13, and -225/+13 but no induction with -111/+13. Electrophoretic mobility shift assays (EMSAs) using -225/-111 as the labeled probe demonstrated enhanced binding activity in nuclear extracts of hypoxic ECs and lung; the appearance of the gel shift band was prevented by excess unlabeled probe (-225/-111), and hypoxia-mediated enhancement of the band was blocked by a probe corresponding to the nuclear factor (NF)-IL-6 site (-158/-145). The hypoxia-enhanced band on EMSA displayed a supershift with antibody to CCAAT-enhancer-binding protein beta (C/EBP-beta), but antibody to C/EBP-alpha or -delta was without effect. Transfection of ECs with a construct comprising thymidine kinase promoter, -225/-111 in either the 5' to 3' to 5' orientation, and the reporter CAT showed this region to be an enhancer (approximately 8-fold) under hypoxia. EMSA with the NF-IL-6 probe revealed a prominent induction of binding activity with nuclear extracts from hypoxic ECs and whole lung. Constructs with -158/-145 and the CAT reporter gene showed induction when transfected into hypoxic ECs, whereas a similar construct with the NF-IL-6 motif mutationally inactivated failed to display hypoxia-induced expression. Furthermore, the tumor necrosis factor (TNF) gene, whose product contributes to ischemic pathology and contains a putative regulatory NF-IL-6 site, demonstrated enhanced binding activity for its NF-IL-6 motif and induction of TNF mRNA based on analysis of hypoxic lung. These data indicate that hypoxia induces expression of IL-6, most likely a result of hypoxic activation at the NF-IL-6 site, and suggest that other genes with regulatory NF-IL-6 sites may also be induced by a similar mechanism.
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PMID:Induction of interleukin 6 (IL-6) by hypoxia in vascular cells. Central role of the binding site for nuclear factor-IL-6. 774 84

We have shown previously that a 500-bp region of the human insulin receptor promoter (-0.3 to -1.8 kb) was able to stimulate transcription from a heterologous thymidine kinase promoter in HepG2 hepatoma cells but not in HeLa fibroblasts. Footprint analysis localized the transcription factor binding sites to a 36-bp region at -1420. In this paper, we analyze the factors that recognize this element and show that it contains binding sites for the CAAT/enhancer binding protein C/EBP and nuclear factor 1 (NF-1). In addition we show that both C/EBP alpha and the C/EBP beta can transactivate the human insulin receptor promoter in a dose-dependent manner.
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PMID:An upstream element from the human insulin receptor gene promoter contains binding sites for C/EBP beta and NF-1. 828 55

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.
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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

We report glucocorticoid-dependent induction of transcription from the herpes simplex virus thymidine kinase gene promoter proximal regulatory region in the absence of glucocorticoid response elements and independent of the ability of glucocorticoid receptor (GR) to bind DNA. Examination of the thymidine kinase promoter localized glucocorticoid responsiveness to a binding site for CCAAT enhancer-binding proteins (C/EBPs). Further analysis indicated that GR specifically potentiated the induction of transcription by C/EBP beta, but not C/EBP alpha or delta, and that full induction could be obtained by the ligand-binding domain (LBD) of GR alone. C/EBP beta, but not C/EBP alpha or delta, reciprocally potentiated transcriptional activation by DNA-bound GR LBD. However, C/EBP beta was unable to increase activation by a GR LBD with a short C-terminal truncation, indicating that the functional interaction between the two factors was dependent upon the GR AF-2. Surprisingly, despite the specificity in functional effects, all three C/EBPs bound indistinguishably to GR in GST pull-down and immunoprecipitation assays. Indeed, several nuclear receptors, including the estrogen (ER alpha), progesterone, retinoic acid (RAR), and androgen receptors, displayed a similar potential to bind C/EBPs. Previous reports have demonstrated that ER alpha and RARs repress transcriptional activation by C/EBP beta in ways that were dependent on their related AF-2 functions. Therefore, the GR AF-2 may encode functional features that distinguish the transcriptional regulatory potential of GR from that of ER and RAR. Finally, C/EBP binding mapped to the GR DNA-binding domain, which was not required for functional interaction with C/EBP beta. Thus, the potentiation of C/EBP beta-mediated transcription by GR would appear to require the presence of an intermediary factor.
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PMID:AF-2-dependent potentiation of CCAAT enhancer binding protein beta-mediated transcriptional activation by glucocorticoid receptor. 981

The hepatitis B viral X protein (HBx) is known to exert its transactivation activity by the interaction with several cellular transcription factors. Here we report the interaction of HBx and CCAAT/enhancer-binding protein alpha (C/EBPalpha) and their effects on the enhancer/promoters of hepatitis B virus (HBV). A chloramphenicol acetyltransferase assay showed that the cotransfection of HBx and C/EBPalpha strongly activated the enhancer II/pregenomic promoter of HBV in a synergistic manner. This effect was also observed in the heterologous expression system with promoters of SV40 and herpes simplex virus thymidine kinase genes. Serial deletion analysis of the enhancer II/pregenomic promoter identified the responsible region (nucleotides 1639-1679), in which two C/EBP-binding sites are located. An in vitro interaction assay and electrophoretic mobility shift assay showed that HBx augmented the DNA binding activity of C/EBPalpha by direct interaction with it, and its basic leucine zipper domain was responsible for the interaction with HBx. Domain analysis of HBx showed that the central region (amino acids 78-103) was necessary for direct interaction with C/EBPalpha. However, the complete form of HBx was necessary for the synergistic activation of the HBV pregenomic promoter. These results suggest that the interaction of HBx and C/EBPalpha enhances the transcription of the HBV pregenomic promoter for the effective life cycle of HBV in hepatocytes.
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PMID:Interaction of hepatitis B viral X protein and CCAAT/ enhancer-binding protein alpha synergistically activates the hepatitis B viral enhancer II/pregenomic promoter. 991 21

The beta(3)-adrenergic receptor (beta(3)AR) is expressed predominantly in adipocytes, and it plays a major role in regulating lipolysis and adaptive thermogenesis. Its expression in a variety of adipocyte cell models is preceded by the appearance of CCAAT/enhancer-binding protein alpha (C/EBP alpha), which has been shown to regulate a number of other adipocyte-specific genes. Importantly, it has been demonstrated that several adipocyte cell lines that fail to express C/EBP alpha exhibit reduced insulin sensitivity, despite an apparent adipogenic phenotype. Here we show that transcription and function of the beta(3)AR correlates with C/EBP alpha expression in these adipocyte models. A 5.13-kilobase pair fragment of the mouse beta(3)AR promoter was isolated and sequenced. This fragment conferred a 50-fold increase in luciferase reporter gene expression in adipocytes. Two putative C/EBP binding sites exist at -3306 to -3298 and at -1462 to -1454, but only the more distal site is functional. Oligonucleotides corresponding to both the wild-type and mutated -3306 element were inserted upstream of a thymidine kinase luciferase construct. When cotransfected in fibroblasts with a C/EBP alpha expression vector, reporter gene expression increased 3-fold only in the wild-type constructs. The same mutation, when placed into the intact 5.13-kilobase pair promoter, reduced promoter activity in adipocytes from 50-fold to <10-fold. Electrophoretic mobility shift analysis demonstrated that the site at -3306 generated a specific protein-oligonucleotide complex that was supershifted by C/EBP alpha antibody, while a probe corresponding to a putative site at -1462 did not. These results define C/EBP alpha as a key transcriptional regulator of the mouse beta(3)AR gene during adipogenesis.
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PMID:CCAAT/enhancer-binding protein alpha is required for transcription of the beta 3-adrenergic receptor gene during adipogenesis. 1102 36

Induction of CYP3A genes by the ligand-activated pregnane-X-receptor (PXR) involves the interaction of other as yet unidentified liver transcription factors. Here we show that the CYP3A1 promoter contains two active sites controlled by the CCAAT/enhancer-binding protein alpha (C/EBPalpha), previously shown to regulate a number of liver stress response genes. We have identified two functional C/EBP binding sites at the CYP3A1 promoter that confer luciferase activity to C/EBPalpha cotransfected CHO cells. When inserted upstream of a thymidine kinase promoter, oligonucleotides corresponding to these elements (-350/-311 and -628/-608), increase reporter gene expression when cotransfected with a C/EBPalpha expression vector. Point mutations in the most conserved nucleotides in either element prevent binding of C/EBPalpha and abolish transactivation of the CYP3A1 promoter. Moreover, we demonstrate that C/EBPalpha accumulates in the rat liver nuclei in response to dexamethasone, and that under these conditions C/EBPalpha binds to the CYP3A1 promoter elements. Our results suggest a correlation between transcription of C/EBPalpha, nuclear protein function and induction of CYP3A1 by dexamethasone in the liver. They also support the notion that C/EBPalpha participates in the up-regulation of the CYP3A1 gene in response to synthetic glucocorticoids.
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PMID:Two CCAAT/enhancer binding protein sites in the cytochrome P4503A1 locus. Potential role in the glucocorticoid response. 1254 5