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)

We have previously characterized the rat pancreatitis-associated protein I (PAP I) gene by nucleotide sequencing. We describe in this paper its promoter region by analysing the regulatory functions associated with the DNA sequence comprising nt -1253 to + 10 of the gene. That sequence strongly promoted the transcription of the promotorless chloramphenicol acetyltranferase (CAT) gene in cells of pancreatic origin (AR-42J) but not in cells of non-pancreatic origin (Rat 2 and IEC 6). The influence on CAT expression of stepwise 5' deletions in the promoter sequence was monitored in the three cell lines. In pancreatic AR-42J cells, deletion down to position -926 did not affect significantly the expression of the reporter gene. Deletion to nt -685 caused about a 30% decrease in expression. Extending the deletion to nt -444 did not have any additional effect, but a further deletion to nt -180, resulted in a reduction to about 25%. Moreover, deletion from nt -180 to -118 resulted in a further reduction to about one-third of that. Finally, deletion down to nt -61 further reduced activity by a factor of 3, although it remained above background. These results suggest the presence of several positive cis-acting elements in the PAP I promoter. In non-pancreatic cells, CAT expression remained very low when the promoter was deleted down to nt -180. Yet, deletion from -180 to -118 significantly increased CAT expression, suggesting suppression of a negative cis-acting element. Further deletion down to nt -61 decreased CAT activity by a factor of 5. The region between nt -180 and -61 was subjected to footprint analysis. A similar pattern of DNase protection was obtained with AR-42J and Rat 2 nuclear extracts, the only protected region extending from nt -125 to -95. That region was further analysed by inserting the nt -180 to -81 fragment, in both orientations, upstream of thymidine kinase (TK) or simian virus 40 (SV40) promoter-CAT constructs. In all cases CAT expression was increased in pancreatic cells but reduced in Rat 2 cells. These results indicated the presence of cell-specific positive and negative elements within that region.
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PMID:Identification of a transcriptional regulatory region of the rat pancreatitis-associated protein I (PAP I) gene that confers tissue specificity. 748 8

Previous analysis of the rat PAP I promoter indicated that the region between nt -180 and -81 possessed silencer activity in cells that did not express PAP I. Based on this finding, we performed a series of experiments to characterize functionally that region and analyze the nuclear proteins interacting with it. Transient transfection assays were conducted in the fibroblast Rat2 cell line, in which PAP I is not expressed, and in the pancreatic cell line AR-42J, expressing PAP I, using the CAT gene as reporter. Experiments in Rat2 cells revealed that the sequence with silencer activity was located within the rep27 region (position -180/-153). Suppressor activity was observed when rep27 was inserted upstream from the core PAP I promoter, in both orientations. By contrast, inserting the rep27 region in front of the promoters of SV40 or thymidine kinase did not affect or weakly enhanced CAT activity. Suppressor activity is therefore position-independent and promoter-dependent. In pancreatic AR-42J cells, rep27 act as a positive element but did not alter CAT expression when inserted in front of the core PAP I promoter or heterologous promoters. Electrophoretic mobility shift assays allowed identification of specific DNA-protein complexes. The shifted complex migrated at the same position with both Rat2 and AR-42J nuclear extracts. Moreover, similar band shifts were obtained with rat nuclear extracts from healthy pancreas, pancreas with acute pancreatitis, liver, kidney, spleen, and small intestine. Results suggest that the rep27 cis-acting element contributes to the tissue specific expression of the PAP I gene. That activity could be mediated by the synergistic action of several transcription factors, one of which being present in all cells.
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PMID:Characterization of a silencer regulatory element in the rat PAP I gene which confers tissue-specific expression and is promoter-dependent. 912 83

HIP/PAP is a C-type lectin overexpressed in hepatocellular carcinoma (HCC). Pleiotropic biological activities have been ascribed to this protein, but little is known about the function of HIP/PAP in the liver. In this study, therefore, we searched for proteins interacting with HIP/PAP by screening a HCC cDNA expression library. We have identified the RII alpha regulatory subunit of cAMP-dependent protein kinase (PKA) as a partner of HIP/PAP. HIP/PAP and RII alpha were coimmunoprecipitated in HIP/PAP expressing cells. The biological relevance of the interaction between these proteins was established by demonstrating, using fractionation methods, that they are located in a same subcellular compartment. Indeed, though HIP/PAP is a protein secreted via the Golgi apparatus we showed that a fraction of HIP/PAP escaped the secretory apparatus and was recovered in the cytosol. Basal PKA activity was increased in HIP/PAP expressing cells, suggesting that HIP/PAP may alter PKA signalling. Indeed, we showed, using a thymidine kinase-luciferase reporter plasmid in which a cAMP responsive element was inserted upstream of the thymidine kinase promoter, that luciferase activity was enhanced in HIP/PAP expressing cells. Thus our findings suggest a novel mechanism for the biological activity of the HIP/PAP lectin.
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PMID:HIP/PAP, a C-type lectin overexpressed in hepatocellular carcinoma, binds the RII alpha regulatory subunit of cAMP-dependent protein kinase and alters the cAMP-dependent protein kinase signalling. 1537 27