Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.13.12.7 (firefly luciferase)
 2,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

B19 parvovirus is absolutely tropic for human erythroid progenitor cells. Among the untested mechanisms underlying this tropism is the possibility of cell-specific positive regulation of the promoter in permissive cells. Using the bacterial chloramphenicol acetyltransferase and firefly luciferase reporter genes, we detected strong activity from the B19 P6 promoter in transfected nonpermissive cells. Very high-level expression was seen in a T lymphoblastoid cell line, CEM. No transcriptional enhancement occurred in an erythropoietin-dependent semipermissive cell line. A putative second B19 promoter at map unit 44 (P44) was nonfunctional and unable to confer tissue specificity. Thus, tropism is unlikely to be regulated at the level of transcriptional initiation from either the P6 or P44 promoter.
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PMID:Indiscriminate activity from the B19 parvovirus p6 promoter in nonpermissive cells. 202 72

The pathogenic human parvovirus B19 contains a promoter at map unit 6 (B19p6) of the viral genome, expression from which is largely restricted to human cells in the erythroid lineage, whereas a putative promoter at map unit 44 (B19p44) is inactive during a natural viral infection. Although nonerythroid human cells, such as HeLa and KB, allow expression from the B19p6 promoter but not from the B19p44 promoter following DNA-mediated transfection, little expression from the B19p6 promoter occurs following recombinant virus infection (S. Ponnazhagan, X.-S. Wang, M.J. Woody, F. Luo, L.Y. Kang, M.L. Nallari, N.C. Munshi, S.Z. Zhou, and A. Srivastava, submitted for publication). However, significant expression from the B19p6 promoter as well as the B19p44 promoter could be detected in a human 293 cells line that expresses the adenovirus early gene products, suggesting that coinfection with adenovirus might mediate transcriptional transactivation of the B19 promoters in nonpermissive cells. Expression of the firefly luciferase reporter gene from the B19 promoters was evaluated either following plasmid transfection or following infection with the recombinant adeno-associated virus type 2 vectors. Both B19p6 and B19p44 promoters could be transactivated by coinfection with adenovirus in nonpermissive human cells, although the extent of transactivation of the B19p44 promoter was significantly lower than that of the B19p6 promoter. Expression of the adenovirus E1A proteins was necessary and sufficient for the observed transactivation of the B19 promoters. These studies further illustrate that the underlying molecular mechanisms of transactivation of parvovirus promoters in general by the adenovirus early proteins have similarities with those of the well-documented transactivation of the adeno-associated virus type 2 promoters.
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PMID:Transcriptional transactivation of parvovirus B19 promoters in nonpermissive human cells by adenovirus type 2. 749 29

We reported previously that an NS2 null mutant of parvovirus H-1 (H-1SA) was capable of lytic growth in human and hamster cells, but not in rat cells (Li and Rhode, 1991). The host-range phenotype of H-1SA was also manifested in newborn rats and was associated with a reduction of viral protein synthesis to about 10% of wild-type virus and an absence of virions in cultured rat fibroblasts. However, the H-1SA mRNAs for NS1 and capsid proteins, R1 and R3, accumulated to wild-type levels and translated well with a cell free rabbit reticulocyte lysate. These results indicate that NS2 plays an important role in the regulation of viral protein synthesis in rat cells in vivo and in vitro, but NS2 is largely dispensable in other types of cells, such as human and hamster cells. To analyze whether the 5' and 3' untranslated regions (UTR) of viral RNA are involved in the regulation by NS2, the viral VP2 gene was replaced by a reporter gene, firefly luciferase, in a plasmid clone of viral sequences and the protein synthesis under the control of P38 was evaluated by luciferase assay. Cells were transfected with luciferase expressing plasmids and subsequently infected with wild-type H-1 or H-1SA. We were able to mimic the defect in expression that we observed in cultured cells and animals with virus infection. Luciferase activity in H- 1SA-infected rat cells was about 10-fold lower than that in H-1-infected rat cells, but only 2-fold lower or less in H-1SA-infected human cells and hamster cells compared to wild-type H-1. These results are consistent with our previous data that NS2 has a host-range phenotype in the natural host of H-1, the rat. Deletion of 5' UTR sequences from P38 transcripts reduced the overall P38-luc expression but expression was NS2 independent, whereas deletion of the terminal 3' UTR sequences of viral RNA reduced NS2-dependent expression in rat cells. These results suggest that the regulation of viral protein synthesis by NS2 depends on RNA sequences in the 3' UTR.
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PMID:The parvovirus H-1 NS2 protein affects viral gene expression through sequences in the 3' untranslated region. 848 Apr 14

Expression from the human parvovirus B19p6 promoter fused to the firefly luciferase ('Luc') reporter gene was evaluated in a non-erythroid human nasopharyngeal carcinoma cell line, KB, and a human megakaryocytic leukaemia cell line, MB-02, known to become permissive for B19 replication following erythroid-differentiation. The B19p6-Luc construct was introduced into KB and MB-02 cells, both in undifferentiated and differentiated states, either via DNA-mediated transfection, or via infection with recombinant adeno-associated virus 2 (AAV), a non-pathogenic human parvovirus known to possess a broad host-range. Although Luc activity was readily detected in KB cells following transfection of the B19p6-Luc plasmid DNA, no expression from the B19p6 promoter was observed following infection with recombinant virus. In addition, transfection of the reporter plasmid resulted in high-level expression of Luc in differentiated but not in undifferentiated MB-02 cells. However, no Luc activity was detected, even in differentiated MB-02 cells, following infection with recombinant virus. Further studies with an additional recombinant as well as wild-type (wt) AAV revealed that MB-02 cells were non-permissive for AAV infection. A second human megakaryocytic leukaemia cell line, M07e, was likewise resistant to infection by recombinant as well as wt AAV. Taken together, these studies identify the first human cell type that cannot be infected by AAV. They indicate that expression from the B19p6 promoter, in the context of an AAV genome, is restricted to primary human haematopoietic cells, perhaps because parvoviral DNA replication and transcription are intrinsically coupled.
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PMID:Differential expression in human cells from the p6 promoter of human parvovirus B19 following plasmid transfection and recombinant adeno-associated virus 2 (AAV) infection: human megakaryocytic leukaemia cells are non-permissive for AAV infection. 868 95