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)

Elements controlling tissue-specific expression of the human atrial natriuretic factor gene have been examined in primary cultures of neonatal rat cardiocytes. When a 68-base pair fragment from human atrial natriuretic factor (hANF) 5'-flanking sequence (positions -400 to -333) was placed upstream from the herpes simplex thymidine kinase promoter linked to a bacterial reporter gene (chloramphenicol acetyltransferase), a tissue-specific positive regulatory effect was observed in atrial as well as ventricular cardiocytes but not in nonmyocardial cells. The cis-acting element in this fragment was orientation- and position-dependent. Examination of nuclear protein extracts for the presence of factors capable of interacting with the 5'-flanking sequence of the hANF gene revealed a cardiocyte-specific factor which bound to the 68-base pair fragment. This association was both tissue- and sequence-specific. These findings indicate that a cis-acting element present in the proximal 5'-flanking sequence confers tissue-specific expression upon the hANF gene, possibly through association with a cardiac-specific nuclear protein.
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PMID:Tissue-specific determinants of human atrial natriuretic factor gene expression in cardiac tissue. 252 32

Atrial and ventricular cardiac muscle cells isolated from 14- to 18-wk old fetal human hearts were grown in culture and characterized. Once established in culture the flattened cells contracted spontaneously and possessed differentiated ultrastructural characteristics including organized sarcomeres, intercalated discs, and transverse tubules with couplings. Atrial granules were present in the cultured atrial cells. Some cultured ventricular myocytes also contained electron-dense granules associated with Golgi cisternae, which were similar in size and appearance to atrial granules. The cultured ventricular myocytes divided and expressed the genes for thymidine kinase, histone H4, myosin heavy chain, muscle-specific creatine kinase, atrial natriuretic factor, and insulin-like growth factor II. These results establish that differentiated fetal human heart muscle cells can be cultured in sufficient quantities for biochemical, molecular, and morphological analyses.
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PMID:Culture and characterization of fetal human atrial and ventricular cardiac muscle cells. 253 44

We have investigated the inhibition of DNA synthesis and cell proliferation by rat atrial natriuretic factor [rANF-(99-126)] and several synthetic peptides that bind selectively to the ANF-C-type clearance receptors in subcultured aortic smooth muscle cells. These peptides decreased serum-induced 1) [3H]thymidine incorporation, 2) cell proliferation, and 3) thymidine kinase activity without altering basal or elevated cAMP or cGMP levels. In contrast, another ANF-C-receptor-binding peptide, des[Gln116,Ser117,Gly118,Leu119,Gly120] rANF-(102-121)-NH2 (cANF), failed to decrease serum-induced mitogenesis, yet 100 nM cANF reversed the inhibition of DNA synthesis and cell proliferation and the decrease of thymidine kinase activity elicited by other C receptor-binding peptides, including rANF-(99-126), rANF-(103-125), and porcine C-type natriuretic peptide [pCNP-(1-22)]. Delayed addition experiments indicated that atrial peptides influence a relatively late event (or events) during the G1 phase of the cell cycle. The inhibition of DNA synthesis by C-receptor-binding atrial peptides appeared to be selective for aortic smooth muscle cells, inasmuch as a potent inhibitory agonist peptide, Cys116-rANF-(102-116), was without significant influence on the incorporation of thymidine in cultured rat mesangial cells or bovine pulmonary artery endothelial cells. These results indicate that atrial natriuretic peptide analogues decrease vascular smooth muscle cell mitogenesis and proliferation by a cyclic nucleotide-independent mechanism involving the C-type receptor. Moreover the inhibition of DNA synthesis by rANF-(99-126) and the neuropeptide pCNP-(1-22) appears to be mediated by the ANF-C-type receptor and is associated with inhibition of thymidine kinase activity.
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PMID:ANF-C-receptor-mediated inhibition of aortic smooth muscle cell proliferation and thymidine kinase activity. 830 41

We have cloned the rat fibroblast growth factor-2 (FGF-2) promoter region including 1058 base pairs (bp) of 5'-flanking DNA. Complete sequencing of this promoter region revealed a 74 bp domain between nucleotides-793 and-720 that was greater than 97% A/G-rich. A repeat of the sequence 5'-AGGGAGGG-3' separated by 11 bp was located at the core of this domain. A 37 bp A/G-rich oligonucleotide containing these AGGG-repeat sequences was synthesised, and tested for function on a minimal herpes simplex virus thymidine kinase (TK) promoter, fused to the firefly luciferase gene (TKp.luc), in transiently transfected neonatal rat cardiac myocytes. Promoter activity was stimulated approximately 3 fold in the presence of AGGG-repeat sequences. This effect was neither tissue or species-specific since TK promoter activity was increased approximately 11 fold in both rat and human glial tumor cells. Four specific complexes (Cl-4) were detected between neonatal rat heart nuclear proteins and the 37 bp A/G-rich oligonucleotide by gel mobility shift assay. Competition with excess unlabelled 37 bp A/G-rich oligonucleotide revealed that two complexes represented very high affinity/specificity interactions (C2 > C4) while Cl and C3 were of lower affinity. As a result, competition with up to a 25 fold molar excess of 37 bp A/G-rich oligonucleotide led to the loss of C2 and C4, and a corresponding and transient increase in the levels of Cl and C3, which themselves were reduced with more competitor oligonucleotide. The AGGG-repeat resembles the 5'-gGGGAGGG-3' sequence previously implicated in the response of the atrial natriuretic factor promoter to the alpha-adrenergic agonist, phenylephrine. Although an additional 1.5 fold increase in TK promoter activity was detected in the presence of the 37 bp A/G-rich oligonucleotide with phenylephrine treatment of transfected myocytes, this effect was not statistically significant. Furthermore, there was no difference in the gel mobility shift (Cl-4) pattern obtained with the 37 bp A/G-rich oligonucleotide and nuclear protein isolated from neonatal rat cardiac myocytes grown in the presence or absence of norepinephrine. These data suggest that the A/G rich sequences in the rat FGF-2 gene 5'-flanking DNA, including the AGGG-repeat, are able to confer stimulatory activity on a promoter in a tissue- and species-independent manner, but alone are not able to induce a significant phenylephrine response in neonatal rat cardiac myocytes.
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PMID:An A/G-rich motif in the rat fibroblast growth factor-2 gene confers enhancer activity on a heterologous promoter in neonatal rat cardiac myocytes. 982 22

1,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) and transforming growth factor beta (TGFbeta) potently induce 5-lipoxygenase (5-LO) in myeloid cells. We analyzed vitamin D receptor (VDR) binding to putative vitamin D response elements within the 5-LO promoter and analyzed its function by reporter gene analysis. Binding of VDR and retinoid X receptor to the promoter region was shown in DNase I footprinting, electrophoretic mobility shift and chromatin immunoprecipitation assays. However, the identified VDR binding region did not mediate induction of reporter gene activity by 1,25(OH)(2)D(3)/TGFbeta, neither in the 5-LO promoter context nor with the thymidine kinase (tk) promoter. Insertion of the rat atrial natriuretic factor VDRE in reporter plasmids containing the 5-LO promoter diminished induction by 1,25(OH)(2)D(3)/TGFbeta as compared with the tk promoter. Similarly, low inductions were obtained when cells were transiently or stably transfected with constructs containing various 5-LO promoter regions. Concerning basal promoter activity, we identified a positive regulatory region (-779 to -229), which includes the VDR binding region, in 5-LO-positive MonoMac6 cells. In summary, the VDR/RXR complex binds to putative VDREs in the 5-LO promoter, but other sequences outside the 5-LO promoter seem to be responsible or additionally required for the prominent induction of 5-LO mRNA expression by 1,25(OH)(2)D(3) and TGFbeta.
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PMID:Analysis of the 5-lipoxygenase promoter and characterization of a vitamin D receptor binding site. 1675 Apr 18