Pyrosequencing is a tool based on bioluminescence reaction for real-time analyzing DNA sequences. The sensitivity of pyrosequencing mainly depends on luciferase in reaction mixture. However, the instability of pyrosequencing reagents caused by fragile wild Photinus pyralis luciferase (PpL) in conventional pyrosequencing usually leads to unsatisfied results, which limits the application of pyrosequencing. In order to improve the stability of pyrosequencing reagents, the coding sequences of mutant thermostable Luciola lateralis luciferase (rt-LlL) was synthesized, and inserted into the plasmid of pET28a(+) to express the thermostable rt-LlL with a 6 x His-tag in the N terminal. The purified rt-LlL with the molecular mass of 60 kDa was obtained by Ni-affinity chromatography. The specific activity of rt-LlL was determined as 4.29 x 10(10) RLU/mg. Moreover, the thermostability of rt-LlL was investigated, and the results showed that rt-LlL had activity at 50 degrees C, and remained 90% of activity after incubated at 40 degrees C for 25 min. Finally, rt-LlL was used to substitute commercial Photinus pyralis luciferase in conventional pyrosequencing reagent to get thermostable pyrosequencing reagent. Comparing with conventional pyrosequencing reagent, the thermostable pyrosequencing reagent is more stable, and it's activity would not lose when incubated at 37 degrees C for 1 h. This study laid foundation of establishing reliable and stable pyrosequencing system which would be applied in Point-of-Care Testing.
Animals ; Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Fireflies ; enzymology ; Luciferases ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Sequence Analysis, DNA ; methods

OBJECTIVETo investigate the roles of Domain I and Domain II of hepatitis C virus (HCV) 5' untranslated region (UTR) in the translation initiation activity of HCV 5'UTR in different host cell lines.

METHODSThe eukaryotic expression plasmid pCMVNCRLuc (pCN1), in which full-length HCV 5'UTR regulates firefly luciferase expression, was modified by deleting Domain I and the downstream single-stranded sequence (43 bp in total) from the UTR (pCNl-d2), Domain I with the downstream single-stranded sequence and Domain II (118 bp in total) from the UTR (pCNl-d3), or the total UTR (pCNl-d5). The modified plasmids were transfected via liposome into different cell lines with pRL-TK plasmid co-transfected as the normalization control. At 36 h after the transfection, the total cellular RNA was harvested for semi-quantitative RT-PCR, and the relative expression activities of luciferase were assayed with a dual luciferase reporter gene assay system. The translation initiation activities of the truncated HCV 5'UTRs in different translation systems were analyzed.

RESULTSDeletion of Domain I and the downstream single-stranded sequence caused no significant changes of the translational activity of HCV 5'UTR in Hela or C6 cells, but decreased the translational activity by 46% in L-02 cells and increased the translational activity by 46% in 293T cells. Deletion of both Domain I and Domain II resulted in decreased translational activity of HCV 5'UTR by 51% in HeLa cells, but increased the translational activity by 40% in L-02 cells, 60% in C6 cells and 135% in 293T cells.

CONCLUSIONSDomain I and Domain II of HCV 5'UTR perform cell type-specific roles in HCV IRES-driven translation initiation.

5' Untranslated Regions ; Genes, Reporter ; HeLa Cells ; Hepacivirus ; genetics ; Humans ; Luciferases ; Plasmids ; Protein Biosynthesis ; genetics ; RNA, Viral ; genetics ; Transfection

OBJECTIVEConstructing a plasmid containing the shRNA of luciferase to suppress the expression of luciferase in BHK-21 cell.

METHODSA 334 bp human U6 snRNA promoter was amplified from human genomic DNA by PCR and ligated to a 21 bp reverse repeated motif of luciferase target sequence with 9 bp spacer and AAV plasmid pSNAV. The recombinant pSNAV/U6/Luc plasmid cotransfected with pMAMneoLuc or transfected luciferase cell line to detect the effect of luciferase expression separately.

RESULTSpSNAV/U6/luc suppresses the luciferase expression from pMAMneoLuc by 50% and luciferase cell line by 70%.

CONCLUSIONSThe results showed that the short hairpin RNA of luciferase can efficiently suppress its expression in BHK-21.

Cell Line ; Gene Expression ; Genetic Vectors ; Humans ; Luciferases ; biosynthesis ; genetics ; Plasmids ; genetics ; Promoter Regions, Genetic ; RNA ; genetics ; Transfection

We developed a method for monitoring of miRNA activity in live cells by a secreted luciferase gene based plasmid sensor named as Gsensor. Firstly, we constructed pAAV2neo-Gluc-MCS-polyA as "empty Gsensor", which contained multiple cloning sites (MCS) for miRNA target inserted. To detect miR142-3p activity, miR142-3p Gsensor and miR142-3p Gsensor-3 were constructed by inserting one or three complementary miR142-3p targets into pAAV2neo-Gluc-MCS-ployA. Subsequently, miR142-3p Gsensor and miR142-3p Gsensor-3 were respectively transfected into U937 cells and Gluc activity was assayed in the supernatant 48 h post transfection. Results showed that both of them effectively indicated miR142-3p activity of inhibiting Gluc expression compared with empty Gsensor. Simultaneously, miR142-3p Gsensor also demonstrated the inhibition of miR142-3p activity by Anti-miR142 when they were cotransfected into U937 cells. This implied one copy of miRNA target in Gsensor was sensitive enough for investigation of miRNA activity. We further analyzed factors affecting Gsensor function including time and dose, and found that miR142-3p activity sensed by miR142-3p Gsensor rose within 48 h post transfection and approached stable thereafter. Transfected dose varying among 0.001-0.05 pg/cell had little effect on its function. Using miR142-3p Gsensor, we further detected miR142-3p activity in HEK293, U937, K562, SP2/0 and P815 cells. Results suggested that miR142-3p activity was high in U937, K562, SP2/0 and P815 cells and almost negative in HEK293. miR142-3p activity was positively correlated with its relative copies in HEK293, U937 and K562 detected by QRT-PCR. In conclusion, Gsensor proved to be an effective tool for monitoring of miRNA activity in live cells, and provide a new method for monitoring miRNA activity in vitro.
Genes, Reporter ; genetics ; Genetic Vectors ; HEK293 Cells ; Humans ; K562 Cells ; Luciferases ; biosynthesis ; genetics ; MicroRNAs ; metabolism ; Transfection ; U937 Cells

OBJECTIVEConstructing a plasmid containing tRNAVal promoter to express shRNA which mediates RNA interference.

METHODSA tRNAVal gene was amplified from human genomic DNA by PCR and replaced the last several bases of 3' end by a linker. The tRNAVal promoter after artificial mutation followed a shRNA sequence to luciferase was cloned into pUC18, Puc-tRNAVal, lucRi Cotransfected with pMAMneoLuc into BHK-21 cell to detect the effect of luciferase expression.

RESULTSpUC-tRNAVallucRi suppressed the luciferase expression from pMAMneoLuc by 97.9%-9.5%.

CONCLUSIONThe results showed that the tRNAVal shRNA plasmid could efficiently suppress luciferase expression in BHK-21.

Animals ; Cell Line ; Genetic Vectors ; Humans ; Luciferases ; biosynthesis ; genetics ; Plasmids ; genetics ; Promoter Regions, Genetic ; RNA Interference ; RNA, Transfer ; genetics

Lentiviral vectors were powerful gene delivery tools for gene therapy. We developed a new lentiviral vector pBobi-MIL that constitutively expressed O6-methylguanine-DNAmethyltransferase (MGMT) and Luciferase, linked by the internal ribosomal entry site (IRES), to realize drug tolerance and real time monitoring in vivo. All results from RT-PCR, drug treating clones forming, immunofluorometric assay and chemiluminescence detection showed that cells infected by recombinant lentivirus L-MIL simultaneously expressed these two genes. This lays the foundation for the further research in gene therapy and can also help identify lentivirus titer.
DNA Modification Methylases ; biosynthesis ; genetics ; DNA Repair Enzymes ; biosynthesis ; genetics ; Drug Resistance ; genetics ; Genetic Therapy ; methods ; Genetic Vectors ; genetics ; Humans ; Lentivirus ; genetics ; metabolism ; Luciferases ; biosynthesis ; genetics ; Tumor Suppressor Proteins ; biosynthesis ; genetics

The study was aimed to analyze the characteristics of LRP16 gene promoter and its activity in order to explore the possible regulation mechanism of LRP16 gene expression. A 2.6 kb genomic DNA sequence of LRP16 5'-end was obtained from NCBI by BLAST software. The 7 target sequences between 0.2 - 2.6 kb from a healthy blood donor DNA sample were amplified by PCR, then identified by DNA sequencing and semi-nest PCR. The verified sequences were analyzed on-line. The results showed that the 7 target sequences were about 400 bp different from each other. All 7 sequences were the same to these GenBank described. At last, all 7 promoter sequences were ligated with luciferase vector, and then the luciferase activity was analyzed in HeLa cells. A known gene promoter sequence can be freely obtained from NCBI database. It is concluded that LRP16 promoter is a standard type II promoter and its activity is strongest in the region from -200 to -600 bp.
Base Sequence ; Chromosomes, Human, Pair 11 ; Gene Expression ; Humans ; Luciferases ; metabolism ; Molecular Sequence Data ; Neoplasm Proteins ; biosynthesis ; genetics ; Promoter Regions, Genetic ; genetics ; Sequence Analysis, DNA

The luminous intensity of dark variant (S1) separated from photobacterium phosphoreum (A2) was 1/10,000 less than that of wild-type. Ethidium bromide (EB) (0.6 mg/L), Mytomycin C (MC, 0.05 mg/L), 2-amino fluorene (2-AF, 1.0 mg/L) all could strongly induce reversion mutation for S1 within 24 h and increase reversion ratio significantly. The results of experiments indicated that these revertants had stable genetic characteristic and the mutation may take place at gene levels. The mutagenesis to S1 caused by EB, MC and 2-AF was detected and it may be used as a new rapid, simple and sensitive method for gene toxicant monitoring.
Ethidium ; pharmacology ; toxicity ; Genetic Variation ; Luciferases ; biosynthesis ; Luminescent Measurements ; Mitomycins ; pharmacology ; toxicity ; Mutagens ; Mutation ; drug effects ; Photobacterium ; genetics ; Toxicology ; methods ; Transcription, Genetic ; drug effects

The luminous intensity of dark variant (S1) separated from photobacterium phosphoreum (A2) was 1/10,000 less than that of wild-type. Ethidium bromide (EB) (0.6 mg/L), Mytomycin C (MC, 0.05 mg/L), 2-amino fluorene (2-AF, 1.0 mg/L) all could strongly induce reversion mutation for S1 within 24 h and increase reversion ratio significantly. The results of experiments indicated that these revertants had stable genetic characteristic and the mutation may take place at gene levels. The mutagenesis to S1 caused by EB, MC and 2-AF was detected and it may be used as a new rapid, simple and sensitive method for gene toxicant monitoring.
*Chemiluminescent Measurements ; Ethidium/pharmacology ; Ethidium/toxicity ; Luciferases/biosynthesis ; Mitomycins/pharmacology ; Mitomycins/toxicity ; Mutagens ; Mutation/*drug effects ; Photobacterium/*genetics ; Toxicology/methods ; Transcription, Genetic/drug effects ; Variation (Genetics)

OBJECTIVETo improve the chemically-activated luciferase expression (CALUX) bioassay for detection of dioxin-like chemicals (DLCs) based on the toxicity mechanisms of DLCs.

METHODSA recombinant vector was constructed and used to transfect human hepatoma (HepG2). The expression of this vector was 10-100 folds higher than that of pGL2 used in previous experiments. The transfected cells showed aromatic hydrocarbon receptor (AhR)-meditated luciferase gene expression. The reliability of luciferase induction in this cell line as a reporter of AhR-mediated toxicity was evaluated, the optimal detection time was examined and a comparison was made by using the commonly used ethoxyresoufin-O-deethylase (EROD) activity induction assay.

RESULTSThe results suggested that the luciferase activity in recombinant cells was peaked at about 4 h and then decreased to a stable activity by 14 h after TCDD treatment. The detection limit of this cell line was 0.11 pmol/L, or 10-fold lower than in previous studies, with a linear range from 1 to 100 pmol/L, related coefficient of 0.997, and the coefficient of variability (CV) of 15-30%.

CONCLUSIONThe luciferase induction is 30-fold more sensitive than EROD induction, the detection time is 68 h shorter and the detection procedure is also simpler.

Biological Assay ; methods ; Carcinoma, Hepatocellular ; pathology ; Cytochrome P-450 CYP1A1 ; biosynthesis ; Environmental Pollutants ; adverse effects ; pharmacology ; Enzyme Induction ; Gene Expression Regulation ; Humans ; Luciferases ; biosynthesis ; Polychlorinated Dibenzodioxins ; adverse effects ; pharmacology ; Sensitivity and Specificity ; Transfection ; Tumor Cells, Cultured