Cloning of gene 1 transactivated by C-terminally truncated middle surface protein of hepatitis B virus

Identification and analysis of rat homologous gene to human HBV pre-S1 protein-binding protein

AIM: To identify and analyze rat homologous gene to human hepatitis B virus (HBV) pre-S1-binding protein (PS1BP) coding gene.

METHODS: The human PS1BP was screened and identified from a hepatocyte expressive cDNA library by phage display technique with purified recombinant pre-S1 protein of HBV as the solidified matrix. The nucleotide sequence database GenBank, established by National Center for Biotechnology Information (NCBI), National Library of Medicine (NLM), National Institute of Health (NIH), was searched for rat cDNA sequence homologous to human PS1BP cDNA by BLASTn tools online. A homologous cDNA sequence was identified as the rat PS1BP cDNA. The similarity and identity of rat PS1BP cDNA and amino acid (aa) sequences to human and mouse PS1BP genes were compared. The potential functional domains were predicted by online analysis tools.

RESULTS: The human PS1BP cDNA was identified by phage display technique. The rat PS1BP cDNA was identified by bioinformatics methods. The rat PS1BP cDNA consisted of 1 455 nt, and encoded a protein of 484 aa. The identity of rat PS1BP protein to human and mouse PS1BP proteins was 80.79% (391/484) and 92.98% (450/484), respectively. In the rat PS1BP protein sequence, several potential modification domains were identified.

CONCLUSION: Rat PS1BP cDNA and protein primary sequences are identified and analyzed.

Screening and identification of genes trans-regulated by HBV pre-S2 protein with cDNA microarray

AIM: To understand the target genes up-regulated or down-regulated by HBV pre-S2 protein, we compared the differentially expressed genes between the hepatoblastoma cell line HepG2 transfected by pcDNA3.1(-) and pcDNA3.1(-)-preS2, respectively with cDNA microarray technique.

METHODS: The HBV pre-S2 coding DNA fragment was amplified with polymerase chain reaction (PCR) technique by using G376-7 plasmid containing the full length of HBV genome as the template. The expressive vector of pcDNA3.1-preS2 was constructed by routine molecular biological methods. The HepG2 cells were transfected by pcDNA3.1(-) and pcDNA3.1(-)-preS2, respectively, using FuGENE6 transfection reagent. The total RNA was isolated and reversely transcribed. The cDNAs were subjected for microarray screening with 1 152 cDNA probes.

RESULTS: The expressive vector was constructed and confirmed by restriction enzyme digestion and DNA sequencing analysis. High quality mRNA and cDNA were prepared and successful microarray screening conducted. From the scanning results, it was found 42 genes were up-regulated and 36 genes down-regulated by pre-S2 protein of HBV.

CONCLUSION: HBV pre-S2 protein is a transactivator. The expression of pre-S2 protein affects the expression spectrum of HBV infected hepatocyte.

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