Screening and identification of genes trans-regulated by a novel HBeAg binding protein E-18 with microarray assay

AIM: To investigate the biological functions of a novel hepatitis B virus e antigen (HBeAg) binding protein E-18, and to use cDNA microarray technique to screen genes regulated by E-18. METHODS: A novel gene E-18 coding for HBeAg was screened and identified by using yeast two-hybrid system 3 and co-immunoprecipitation technique. The E-18 coding DNA fragment was amplified by reverse transcription polymerase chain reaction (RT-PCR) technique from HepG2 cell. The expressive vector of pcDNA3.1-E-18 was constructed by routine molecular biological methods. The HepG2 cells were transfected with pcDNA3.1(-) and pcDNA3.1-E-18, respectively by using lipofectamine. The total RNA was isolated and reverse transcribed. The cDNA of each sample were subjected to microarray screening with 1 152 cDNA probes and analyzed by bioinformatics. RESULTS: E-18 cDNA sequence was obtained and identified by yeast two-hybrid screening and bioinformatics analysis. The expressive vector was constructed and confirmed by DNA sequencing analysis and restriction enzyme digestion. High quality mRNA and cDNA of transfected HepG2 cells had been prepared and successful microarray screening conducted. From the scanning results, there were 52 differential expression genes, of which 36 genes were down-regulated, and 16 genes were up-regulated. CONCLUSION: Microarray technique is successfully used to screen the genes trans-regulated by E-18. The expression of E-18 protein affects the expression spectrum of HepG2 cell.