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 this paper clinical similarities between sickle cell anemia patients and zinc deficient subjects, the latter as reported from the Middle East have been presented. Zinc levels in plasma, red cells, hair and neutrophils were decreased in our adult patients with SCA. The activities of certain zinc dependent enzymes such as plasma RNase, red cell carbonic anhydrase, leucocyte alkaline phosphatase, and deoxythymidine kinase activity in freshly synthesized collagen connective tissue were consistent with the concept that indeed zinc deficiency occurred in SCA patients. Zinc supplementation under controlled conditions showed that the SCA patients gained weight, their serum testosterone level increased and plasma ammonia level decreased. Finally, we also observed abnormal dark adaptation in some SCA patients which improved following zinc supplementation. Inasmuch as we have previously reported that the number of irreversible sickle cells decrease following zinc supplementation, we would like to suggest that zinc supplementation at earlier age may be benefical in preventing organ damage. In conclusion, zinc supplementation should be prescribed for patients with SCA, particularly if they show evidences for zinc deficiency.
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PMID:Zinc deficiency and effects of zinc supplementation on sickle cell anemia subjects. 729 Dec 6

We have produced and characterized lines of transgenic mice expressing a fusion gene composed of the pituitary expression-specific promoter region of the POMC gene, driving the herpes simplex viral-1 thymidine kinase. Adult mice were treated with the antiherpes agent ganciclovir at 70 mg/kg body weight (ip, twice daily for 10-12 days). Approximately 98% of the pituitary intermediate lobe melanotropes and anterior lobe corticotropes were ablated as determined by immunocytochemistry and RIA specific for the POMC-derived peptides, ACTH, beta-endorophin, and alpha-MSH. The number of lactotropes, somatotropes, thyrotropes, and gonadotropes was not altered compared with controls, indicating that in the adult pituitary, POMC products are not required to maintain the distribution of cell types. As expected, plasma corticosterone levels were substantially decreased after POMC cell ablation. In situ hybridization studies showed that the mouse ACTH receptor was expressed uniformly throughout the adrenal cortex, and RNase protection assays revealed that the ACTH receptor mRNA decreased after pituitary POMC cell ablation. Additionally, RNase protection assays showed that pituitary POMC cell ablation resulted in the decrease of adrenal p450c11 beta transcripts while p450c11AS (aldosterone synthase) mRNA levels remained constant. These data demonstrate differential regulation of steroid pathway-specific enzymes by POMC products. Our results also suggest that the thymidine kinase cell obliteration technique may not be dependent on cell division as a prerequisite for cytotoxicity, thus supporting the idea that targeted molecular ablation using cell- and tissue-specific promoter sequences to drive viral thymidine kinase expression can be refined further to study other nonmitotic cells.
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PMID:Targeted ablation of pituitary pre-proopiomelanocortin cells by herpes simplex virus-1 thymidine kinase differentially regulates mRNAs encoding the adrenocorticotropin receptor and aldosterone synthase in the mouse adrenal gland. 747 75

The infected cell protein 4 (ICP-4), the major regulatory protein encoded by the a4 gene of the herpes simplex virus 1, binds two sites (alpha 4-1 proximal, alpha 4-1 distal) at the 5'-untranscribed domain and at the transcription initiation site (alpha 4-2) of the alpha 4 gene. Chimeric genes consisting of the 5'-untranscribed and transcribed noncoding domains of the alpha 4 gene fused to the coding sequences of the thymidine kinase gene were mutagenized to abolish binding of ICP-4 by substitution of bases, including the guanines whose methylation interferes with binding of the protein, and recombined into the viral genome. The cytoplasmic RNAs extracted from infected cells treated with cycloheximide, from untreated infected cells maintained for 4 or 8 hr, and from cells infected first with a virus deleted in the alpha 22 gene and 3 hr later with the test viruses were tested in RNase protection assay for amounts of the chimeric gene RNA relative to amounts of alpha 22 gene RNA. We report the following: (i) Mutation of the alpha 4-2 binding site resulted in a 5-to 6-fold higher accumulation of chimeric gene RNA at 4 hr and as much as 15-fold higher accumulation by 8 hr after infection. (ii) Mutations of alpha 4-1 sites by themselves had no effect on RNA accumulation. However, mutagenesis of all three sites significantly increased mRNA amounts above the levels seen in cells infected with alpha 4-2 site mutants. (iii) The mutations have no effect on accumulation of alpha 4 mRNA in the absence of ICP-4 synthesis and, therefore, the mutations had no effect on RNA stability or transcription rate. (iv) Accumulation of alpha 4 mRNA relative to that of alpha 22 mRNA is highest in the presence of cycloheximide and decreases with time after infection. We conclude that ICP-4 autoregulates the transcription of its own gene in infected cells and that binding of ICP-4 to three sites in its promoter is additive in its effects on this process.
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PMID:Repression of the herpes simplex virus 1 alpha 4 gene by its gene product occurs within the context of the viral genome and is associated with all three identified cognate sites. 838 19

Recombinant adeno-associated virus 2 (AAV) virions were constructed that contained the genomic copy of a normal human beta-globin gene marked with a 4-bp Clal linker, and the herpesvirus thymidine kinase (TK) promoter-driven bacterial gene for resistance to neomycin (v beta m-globin), as well as those containing the DNase l-hypersensitive site 2 (HS-2) from the locus control region (LCR) of the human beta-globin gene cluster (vHS2-beta m-globin). These recombinant virions were used to infect a human erythroleukemia cell line which normally does not express the beta-globin gene (K562), or a human nasopharyngeal carcinoma cell line (KB). Cell populations resistant to G418, a neomycin analogue, were obtained following infections with the recombinant virions, indicating high-efficiency transduction of the chimeric gene as well as functional activity of the transduced neo gene in both cell types. Southern blot analysis using a human beta-globin DNA probe substantiated stable integration of the exogenous beta-globin allele in these cells. There was no expression of the transduced beta-globin gene in K562 or KB cells infected with the v beta m-globin virus. High-level expression of the transduced beta-globin gene occurred only in the vHS2-beta m-globin virus-infected K562 cells, but not in KB cells, as determined by Northern blot as well as RNase protection analyses. Expression of the human beta-globin protein could also be detected in approximately 10-20% of the vHS2-beta m-globin virus-infected K562 cells. These studies suggest that the AAV-based vector system may prove useful for high-efficiency globin gene transfer in human hematopoietic cells.
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PMID:Adeno-associated virus 2-mediated transduction and erythroid cell-specific expression of a human beta-globin gene. 864 53

Multiple variant alleles of the human arylamine N-acetyltransferase genes, NAT1* and NAT2*, alter the capacity of individuals to metabolize arylamines by N-acetylation. Although biochemical and genetic studies have improved our understanding of the molecular basis of the acetylation polymorphism in humans and other mammals, regulation of NAT* gene expression is not understood. In the present study, a segment of the 5'-untranslated region of mouse Nat2* was sequenced and characterized. Primer extension analysis and RNase protection assays exposed multiple transcription initiation sites located 112 to 151 bases upstream of the translational start site. Computer sequence analysis revealed a promoter-like region located within the region 530 bases upstream of the translational start site consisting of TATA boxes, upstream promoter elements such as a CAAT box and Sp1 binding site, regulatory elements such as a palindromic hormone response element (HRE), and enhancer regions such as an AP-1 transcription factor binding site. Transient expression of CAT reporter constructs of the mouse Nat2*-palindromic HRE demonstrated positive regulation of the HSV-thymidine kinase 1 (tk1) promoter and induced the expression of chloramphenicol acetyltransferase (CAT). This induction was initiated by the addition of hormones such as 5alpha-dihydrotestosterone (DHT) or dexamethasone and was entirely dependent on the presence of androgen or glucocorticoid receptors, respectively. Together with recent discoveries regarding the effects of testosterone on the expression of Nat2* in mouse kidney during development, the findings reported in this article suggest that the HRE found in the promoter region of Nat2* is a potential candidate for the mediation of androgenic regulation of Nat2* in mouse kidney.
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PMID:Characterization of a hormone response element in the mouse N-acetyltransferase 2 (Nat2*) promoter. 957 94

The retinoblastoma tumor suppressor gene product (pRb) is involved in controlling cell cycle progression from G1 into S. pRb functions, in part, by regulating the activities of several transcription factors, making pRb involved in the transcriptional control of cellular genes. Transient-transfection assays have implicated pRb in the transcription of several genes, including c-fos, the interleukin-6 gene, c-myc, cdc-2, c-neu, and the transforming growth factor beta2 gene. However, these assays place the promoter in an artificial context and exclude the effects of far 5' upstream regions and chromosomal architecture on gene transcription. In these experiments, we have studied the role of pRb in the control of cell cycle-related genes within a chromosomal context and within the context of the G1 phase of the cell cycle. We have used adenovirus vectors to overexpress pRb in human osteosarcoma cells and breast cells synchronized in early G1. By RNase protection assays, we have assayed the effects of this virus-produced pRb on gene expression in these cells. These results indicate that pRb is involved in the transcriptional downregulation of the E2F-1, E2F-2, dihydrofolate reductase, thymidine kinase, c-myc, proliferating-cell nuclear antigen, p107, and p21/Cip1 genes. However, it has no effect on the transcription of the E2F-3, E2F-4, E2F-5, DP-1, DP-2, or p16/Ink4 genes. The results are consistent with the notion that pRb controls the transcription of genes involved in S-phase promotion. They also suggest that pRb negatively regulates the transcription of two of the transcription factors whose activity it also represses, E2F-1 and E2F-2, and that it plays a role in downregulating the immediate-early gene response to serum stimulation.
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PMID:Regulation of cellular genes in a chromosomal context by the retinoblastoma tumor suppressor protein. 967 66

Sodium butyrate causes alteration of colon cancer cell morphology and biology towards that of a more differentiated phenotype. The retinoblastoma gene encodes a nuclear phosphoprotein (pRb) present in a wide range of human cancer cell lines including colon cancer cell lines. pRB is synthesized throughout the cell cycle and phosphorylated in a phase specific manner: the predominant proteins in G0/G1 are the unphosphorylated species (110 kD) whereas phosphorylated pRb (112-114 kD) are in S and G2. 110 kD pRb binds transcription factors and prevents transcription of responsive genes such as the gene for thymidine kinase, which are expressed in late G1. The precise mechanisms controlling cell arrest are unknown, but recent data suggest that cyclin-dependent kinase inhibitors such as p16 may play a role. The aim of the present study was to assess the effect of sodium butyrate on cell cycle staging, thymidine kinase activity, phosphorylation of the pRb protein and expression of p16. We show that sodium butyrate treatment induces differentiation of LS174T colon cancer cells, inhibits thymidine kinase activity concomitantly with induction of pRb dephosphorylation, p16 transcription and cell cycle arrest at G0/G1. Initial dephosphorylation was observed 24 h after treatment of LS174T cells with sodium butyrate, whereas complete shift to the dephosphorylated form was observed 3 days after treatment. Induction of pRb dephosphorylation by sodium butyrate preceded inhibition of growth and the specific cell cycle arrest. RNase protection assay with a p16 specific riboprobe showed undetectable levels in proliferating cells to several fold increase in differentiated colonocytes. In conclusion, the results provide evidence for a specific cellular mechanism of butyrate induced growth arrest and differentiation of a colon cancer cell line.
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PMID:Sodium butyrate induces retinoblastoma protein dephosphorylation, p16 expression and growth arrest of colon cancer cells. 982 7

Several lines of evidence indicate that the number of GnRH receptors (GnRH-R) and therefore, gonadotrope responsiveness to GnRH, is highly dependent upon the level of GnRH-R mRNA. To explore this aspect of regulation, we have isolated a 3.3 kb fragment encompassing the promoter region of the rat GnRH-R gene. Primer extension and RNase protection assays allowed the identification of five major transcriptional start sites located within the 110 bp region upstream of the translation start codon. Transfection experiments using the CAT reporter gene demonstrated that the 1261 bp 5' flanking region is required to direct high efficient expression in the gonadotrope-derived alphaT3-1 cell line thus contrasting with mouse in which the only 500 bp proximal sequence appeared to be sufficient. Another difference between rat and mouse was apparent in the 183 bp region of the rat promoter which induced a 3-fold stimulation of thymidine kinase promoter activity in both alphaT3-1 and CHO cells. Subsequent deletion analysis of the region residing between -1261 and -519 revealed the presence of multiple regulatory domains that contributed to the cell-specific activity. However, despite this efficiency in the context of the wild-type promoter, they failed to induce the activity of the minimal thymidine kinase (TK) promoter in the absence of the proximal 600 bp promoter region. Accordingly, a composite TK promoter containing the entire 1.2 kb promoter induced a 10-fold increase in the activity of the TK promoter in alphaT3-1 cells. Taken together these data suggest that distal regulatory regions are critical and require cooperation with proximal specific-promoter elements for activating basal R-GnRH gene expression in gonadotrope cells.
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PMID:Multiple elements in the distal part of the 1.2 kb 5'-flanking region of the rat GnRH receptor gene regulate gonadotrope-specific expression conferred by proximal domain. 986 30

An open reading frame (ORF) situated between the U(L)20 and U(L)21 genes encodes a protein designated as U(L)20.5. The U(L)20.5 ORF lies 5' and in the same orientation as the U(L)20 ORF. The expression of the U(L)20.5 ORF was verified by RNase protection assays and by in-frame insertion of an amino acid sequence encoding an epitope of an available monoclonal antibody. The tagged U(L)20.5 protein colocalized in small dense nuclear structures with products of the alpha22/U(S)1.5, U(L)3, and U(L)4 genes. Expression of the U(L)20.5 gene was blocked in cells infected and maintained in the presence of phosphonoacetate, indicating that it belongs to the late, or gamma(2), kinetic class. U(L)20.5 is not essential for viral replication inasmuch as a recombinant virus made by insertion of the thymidine kinase gene into the U(L)20.5 ORF replicates in all cell lines tested [J. D. Baines, P. L. Ward, G. Campadelli-Fiume, and B. Roizman (1991) J. Virol. 65, 6414-6424]. The genomic location of the recently discovered genes illustrates the compact nature of the viral genome.
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PMID:Identification of a novel expressed open reading frame situated between genes U(L)20 and U(L)21 of the herpes simplex virus 1 genome. 1063 14

A human immunodeficiency virus type 1 (HIV-1)-based retroviral vector pseudotyped with HIV envelope containing the herpes simplex virus-thymidine kinase (HSV-TK) gene under the control of the HIV LTR promoter (pHXTKN) was constructed and stably transferred into human CD4(+) H9, CEM, and U937 cells. RNase protection assays did not initially detect expression of the HSV-TK gene in HXTKN-transduced CD4(+) cells (HXTKN/CD4), but expression was then efficiently induced by infection with HIV-1. MTT assays showed that after HIV-1 infection, the susceptibility of HXTKN/CD4 cells to ganciclovir (GCV) was 1000-fold higher than prior to infection. This enabled HIV-1-infected cells to be selectively killed by transduction with HXTKN followed by exposure to GCV. Because the HSV-TK gene is specifically transferred into HIV-1-permissive cells and expressed only after HIV-1 infection, the frequency of unwanted cell death should be low. Elimination of the HIV-1-infected cells effectively inhibited further spread of infectious virus. In addition, the integrated HIV vector sequences were repackaged on infection with HIV-1 and transferred to surrounding untransduced cells. These results are indicative of the potential benefits of using HIV vectors in gene therapies for the treatment of HIV-1 infection.
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PMID:Selective killing of human immunodeficiency virus-infected cells by targeted gene transfer and inducible gene expression using a recombinant human immunodeficiency virus vector. 1117 60


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