Trichloroethylene Induces Biphasic Concentration-dependent Changes in Cell Proliferation and the Expression of SET-Associated Proteins in Human Hepatic L-02 Cells

Trichloroethylene （TCE） is a major pollutant that affects both occupational and general environments. The liver is an important target organ of TCEE. Substantial efforts and remarkable progress into understanding TCE cytotoxicity have been made in cultured liver cells. However, the molecular mechanisms by which TCE induces hepatotoxicity are not well understood. SET （also known as protein phosphatase 2A inhibitor, 12PP2A, or template-activating factor-I, TAF-D is a nuclear protein that regulates histone modification, gene transcription, DNA replication, nucleosome assembly,

Expression and semi-quantification of hepatitis B virus reverse transcriptase protein in a prokaryotic system

The reverse transcriptase （RT） protein of hepatitis B virus （HBV） has been successfully expressed by recombinant technology in Eschericahia coli （ E. coli ）. In this study we aimed to develop a semi-quantitative assay for the study of HBV RT protein using this system. Complete HBV polymerase gene from a wild type virus （rt306P） and the polymerase gene from a mutant, with rt306P substituted by serine （rtP306S） were separately fused to the maltose binding protein （MBP） gene and expressed in E. coli respectively. The expression levels of HBV polymerase genes from the wild type virus and its counterpart mutant at rt306 were compared. When these proteins were semi-quantified by Westem blotting using rabbit anti-TP serum, the rtP306S mutant showed decreased expression of MBP-HBV polymerase. By this method, we have shown that the expression level of HBV RT could be affected by substitutions in its amino acid sequences, and this method could be used to study the characteristics of HBV RT protein.

STRUCTURE IN THE PRECORE REGION OF HEPATITIS B CORE GENE AFFECTING ITS EXPRESSION IN E.coil

Restriction fragments of HBV-DNA, cleaved by endonuclease HhaI,containing HBcAg gene were trimmed by BAL-31 exonuclease to remove different lengths of the precore sequence.They were inserted into plasmid pUR222 at EcoRI site through synthetic linker ligation. Transformants in E.coli BMH7118 showing different levels of HBcAg gene expression were screened and analyzed for their nucleotide sequences in the junction region both by Maxam and Gilbert's chemical degradation method and by M13 chain termination method. Results of sequence analysis of different transformants revealed a partial palindromic (loop and stem) structure, at -7 to -35 nucleotide with regard to ATG of the HBcAg gene as position +1, which has dramatic effect on the level of expression of the inserted gene using the same promoter,SD sequence and identical N-terminus.The amount of HBcAg synthesized differed from 9% in the high expressing plasmid to less than 0.01% of the total cell proteins in the low expressing transformants.The findings were compared to results obtained by other workers in studies of HBcAg expression in procaryotes and their significance in the expression of eucaryotic genes in procaryotic cells were discussed.

A microarray analysis of early activated pathways in concanavalin A-induced hepatitis

Objective:To explore the mechanisms of fulminant hepatitis(FH) in the early stages,and to determine the critical pathways in its initiation and progression.Methods:Twelve BALB/c mice were divided into four groups:one group left as negative control and sacrificed immediately after injection of phosphate-buffered saline(PBS),and another three groups with concanavalin A(Con A) administration sacrificed at 1,3,and 6 h after injection.Affymetrix GeneChip Mouse 430 2.0 Array was employed to evaluate the expression profile of each of the 12 samples.Further analysis was done on the microarray data to extract the genes that were differentially expressed.Enrichment analysis was carried out to determine relevant pathways within which regulated genes were significantly enriched.Results:A total of 393,8354 and 11 344 differentially expressed genes were found,respectively,at three time points.During 0-1 h and 1-3 h,most of the pathways enriched with regulated genes were related to immune response and inflammation,among which Toll-like receptor(TLR) signaling and mitogen-activated protein kinase(MAPK) signaling appeared during both phases,while cytokine-cytokine receptor interaction,apoptosis,T cell receptor signaling,and natural killer(NK) cell-mediated cytotoxicity pathways emerged during the second phase.Pathways found to be significant during 3-6 h were mostly related to metabolic processes.Conclusion:The TLR signaling pathway dominates the early responses of Con A-induced FH in mice.It stimulates the production of type I cytokines,therefore recruiting and activating T/NK cells.Activated T/NK cells exert their cytotoxicity on hepatocytes through inducing death receptorintermediated apoptosis,resulting in liver injury.