Transcriptional activators are required to turn on the expression of genes in a eukaryotic cell. Activators bound to the enhancer can facilitate either the recruitment of RNA polymerase II to the promoter or its elongation. This article examines a few selected issues in understanding activator functions and activation mechanisms.
Animals ; Humans ; Trans-Activators ; genetics ; metabolism ; Transcription Factors ; genetics ; metabolism ; Transcription, Genetic ; Transcriptional Activation

To determine the feasibility of a nonradioactive electrophoresis mobility shift assay for detecting nuclear transcription factor, double-stranded oligonucleotides encoding the consensus target sequence of NF-kappa B were labelled with DIG by terminal transferase. After nuclear protein stimulated with phorbol 12-myristate 13-acetate (PMA) or PMA and pyrrolidine dithiocarbamate (PDTC) electrophoresed on 8% nondenaturing poliacrylamide gel together with oligeonucleotide probe, they were electro-blotted nylon membrane positively charged. Anti-DIG-AP antibody catalyzed chemiluminescent substrate CSPD to image on X-film. The results showed that nuclear proteins binded specifically to the NF-kappa B consensus sequence in the EMSA by chemiluminescent technique method and the activity of NF-kappa B in PMA group was more than that in PMA + PDTC group. It is suggested that detection of NF-kappa B by EMSA with chemiluminescent technique is feasible and simple, which can be performed in ordinary laboratories.
Chemiluminescent Measurements ; DNA-Binding Proteins/*analysis ; DNA-Binding Proteins/genetics ; Electrophoretic Mobility Shift Assay ; NF-kappa B/*analysis ; NF-kappa B/genetics ; NF-kappa B/metabolism ; Rats, Sprague-Dawley ; *Trans-Activation (Genetics) ; Trans-Activators/analysis ; Trans-Activators/genetics ; *Transcription, Genetic

Cell Differentiation ; Cell Line, Tumor ; metabolism ; Cell Proliferation ; Humans ; Trans-Activators ; biosynthesis ; genetics ; Transfection

OBJECTIVESTo investigate the effect of hepatitis B virus X protein (HBx) on adriamycin-induced apoptosis of hepatocellular carcinoma cells.

METHODSHBx gene fragment was amplified from subtype adr HBV plasmid by PCR, and inserted into Hind III and Kpn I sites of green fluorescent protein (GFP) eukaryotic expression vector pEGFP-C1 to construct recombinant pGFP/HBx. The pEGFP-C1 and pGFP-HBx were introduced into HepG2 cells by Lipofectamine 2000 to obtain HepG2 cells expressing GFP. GFP-HBx fusion protein was selected using G418. The expression of HBx gene was demonstrated by RT-PCR analysis. HepG2, HepG2/GFP and HepG2/GFP-HBx cells were treated with adriamycin (2.5 microg/ml), and apoptosis of the cells was determined by their morphological changes, trypan blue exclusion, and flow cytometry analysis.

RESULTSUnder a fluorescence microscope, visible expression of GFP and GFP-HBx fusion proteins were observed in HepG2/GFP and HepG2/GFP-HBx cells, even after growing over 70 generations. RT-PCR analysis showed that HBx gene was expressed in HepG2/GFP-HBx cells. Trypan blue exclusion showed adriamycin induced time-dependent cell death in HepG2 and HepG2/GFP cells while no significant cell death was observed in HepG2/GFP-HBx cells. Flow cytometry analysis showed that apoptosis rates in HepG2/GFP-HBx (3.94%) cells were significantly lower than those in HepG2 (59.03%) and HepG2/GFP cells (61.38%) at 36 hours after the adriamycin treatment (P < 0.01). No significant differences of apoptosis rates of HepG2/GFP-HBx (3.94%) and of the untreated cells (2.12%, 2.78%, 2.55%) (P > 0.05) were observed.

CONCLUSIONA HepG2 cell line expressing GFP and GFP-HBx fusion proteins was successfully established. HBV X protein blocks adriamycin-induced apoptosis of these HepG2 cells.

Apoptosis ; drug effects ; Doxorubicin ; pharmacology ; Hep G2 Cells ; Humans ; Plasmids ; Trans-Activators ; genetics

In order to study function of NAC transcription in development, hormone regulation and the stress response of Salvia miltiorrhiza, the NAC transcription was cloned and analyzed. By retrieving cDNA database of S. miltiorrhiza hairy root one NAC unigene was found, then a full length of cDNA was cloned by designing specific primers and PCR amplifying. Using ORF finder it was found that the cDNA containing a NAC-AB conserved domain in N-terminal, so the cDNA was a NAC transcription factor, named as SmNAC1 (kF006346). Bioinformatics analysis showed that SmNAC1 had an open reading frame (ORF) of 591 bp encoding 196 amino acids. The calculated protein had isoelectric point (pI) of 4.36 with molecular weight about 21.66 kDa. The transcription level of SmNAC1 after dealing with yeast extract (YE) and silver ion (Ag+) in S. miltiorrhiza hairy root was markedly stimulated up regulating. It was 1.4 fold compared with the control after induction 2 h, and maintained 2.0 fold on 4-12 h after induction. SmNAC1 may participate in regulation of stress response of YE + Ag+.
Cloning, Molecular ; Computational Biology ; Phylogeny ; Plant Proteins ; genetics ; physiology ; Plant Roots ; chemistry ; Salvia miltiorrhiza ; chemistry ; genetics ; Trans-Activators ; genetics ; physiology

OBJECTIVETo construct a retroviral vector carrying HBX gene and investigate its expression in LO2 human hepatocytes.

METHODSHBX gene was amplified by PCR and subcloned into the retroviral vector pSEB-Flag to construct a retroviral plasmid (pSEB-Flag-HBX) expressing HBX. The HBX gene insert was confirmed by restriction enzyme digestion, PCR and DNA sequencing. The recombinant retroviruses carrying HBX gene were generated in 293T cells co-transfected with pSEB-Flag-HBX and the packaging plasmids pAmpho, and used to infect LO2 human hepatocyte. After selection with blasticidin, the mRNA and protein expressions of HBx were determined by the reverse transcription-PCR and Western blotting, respectively.

RESULTSThe retroviral plasmid (pSEB-Flag-HBX) carrying HBX was constructed successfully. The recombinant retrovirus efficiently delivered HBX gene into LO2 human hepatocyte, resulting in stable expression of HBX mRNA and HBx protein as shown by RT-PCR and Western blotting, respectively.

CONCLUSIONThe recombinant retrovirus pSEB-Flag-HBX has been successfully constructed, which is capable of delivering the target gene HBX into LO2 human hepatocytes and results in stable expression of HBx to serve as an ideal model to study the effect of HBx on the development of hepatocellular carcinoma.

Cell Line ; Gene Expression ; Genetic Vectors ; Hepatocytes ; cytology ; Humans ; Plasmids ; RNA, Messenger ; genetics ; Retroviridae ; genetics ; Trans-Activators ; biosynthesis ; genetics ; Transfection

Tripterygium wilfordii multiglycoside (GTW) is a commonly used compound for the treatment of rheumatoid arthritis (RA) and immune diseases in clinical practice. However, it can induce liver injury and the mechanism of hepatotoxicity is still not clear. This study was designed to investigate GTW-induced hepatotoxicity in zebrafish larvae and explore the mechanism involved. The 72 hpf (hours post fertilization) zebrafish larvae were administered with different concentrations of GTW for three days and their mortality, malformation rate, morphological changes in the liver, transaminase levels, and histopathological changes in the liver of zebrafish larvae were detected. The reverse transcription-polymerase chain reaction (RT-PCR) was used to examine the levels of microRNA-122 (miR-122) and genes related to inflammation, apoptosis, cell proliferation and liver function. The results showed that GTW increased the mortality of zebrafish larvae, while significant malformations and liver damage occurred. The main manifestations were elevated levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), significant liver atrophy, vacuoles in liver tissue, sparse cytoplasm, and unclear hepatocyte contours. RT-PCR results showed that the expression of miR-122 significantly decreased by GTW; the mRNA levels of inflammation-related genes il1β, il6, tnfα, il10, cox2 and ptges significantly increased; the mRNA level of tgfβ significantly decreased; the mRNA levels of apoptosis-related genes, caspase-8 and caspase-9, significantly increased; the mRNA level of bcl2 significantly decreased; the mRNA levels of cell proliferation-related genes, top2α and uhrf1, significantly reduced; the mRNA levels of liver function-related genes, alr and cyp3c1, significantly increased; and the mRNA level of cyp3a65 significantly decreased. In zebrafish, GTW can cause increased inflammation, enhanced apoptosis, decreased cell proliferation, and abnormal expression of liver function-related genes, leading to abnormal liver structure and function and resulting in hepatotoxicity.
Animals ; Apoptosis ; Chemical and Drug Induced Liver Injury/genetics* ; Inflammation/genetics* ; Trans-Activators ; Tripterygium ; Zebrafish/genetics* ; Zebrafish Proteins

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in China, which is mainly caused by hepatitis B virus (HBV) infection. The X gene product (HBx) of HBV has extensive trans-activating functions. HBx affects the signal transduction, apoptotic cell death and cell cycle through interaction with variety intracellular proteins in infected hepatocytes. In view of the importance of HBx in HBV replication and in hepatic cell functions, the role of HBx in HCC development has been attracting great attention.
Carcinoma, Hepatocellular ; pathology ; Hepatitis B virus ; genetics ; physiology ; Humans ; Liver Neoplasms ; pathology ; Trans-Activators ; genetics ; physiology ; Virus Replication ; physiology

Carcinoma, Hepatocellular ; virology ; Hepatitis B virus ; genetics ; isolation & purification ; Humans ; Liver Neoplasms ; virology ; Mutation ; Trans-Activators ; genetics

Apoptosis ; Cell Line ; Cell Line, Tumor ; Genes, Viral ; Hepatitis B virus ; genetics ; Hepatocytes ; cytology ; Humans ; Trans-Activators ; genetics