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Screening of binding protein of hepatitis B virus pre-pre-s promoter by phage display technique

AIM: To screen the binding protein gene of hepatitis B virus pre-pre-s promoter using phage display technique.

METHODS: Taking HBV pre-pre-S promoter as a solidified selective molecule, the phage-human liver cDNA library was biopanned and the positive clones were selected. The positive plaques were amplified and then cloned into pGEM-Teasy vector. The selected positive plaques were analyzed using bioinformatics and DNA sequencing.

RESULTS: Twenty positive clones were obtained, which included 17 clones with known function and 3 with unknown function.

CONCLUSION: The binding protein genes of HBV pre-pre-s promoter can be obtained by phage display technique, which may be helpful for further study of the pathogenesis of HBV infection.

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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Identification and characterization of retinol dehydrogenase 11 as a hepatitis C virus core protein-binding protein by yeast-two hybrid technique

AIM: To screen the hepatocyte protein interacting with HCV core protein.

METHODS: By using HCV core protein as a bait, yeast-two hybrid system 3 was employed for screening and identification of HCV core protein-binding proteins from a hepatocyte cDNA library expressed in yeast cells. The protein-protein interaction was confirmed by back-cross experiment, and the inserts of the expressive vectors were sequenced and analyzed by bioinformatics methods.

RESULTS: Among them we identified retinol dehydrogenase 11(RDH11/androgen- regulated short-chain dehydrogenase/reductase 1 (ARSDR1) as a HCV core protein-interacting protein. This is the first time, to the best of our knowledge, to know the fact that there are interactions of HCV core protein-retinol dehydrogenase 11.

CONCLUSION: The identification of retinol dehydrogenase 11 as the HCV core protein binding partner paves a new way for further understanding of the pathogenesis of HCV infection.

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Cloning of the gene of preS1 promoter of hepatitis B virus specific DNA-binding protein 1

AIM: To identify the protein which has unknown function binding with the preS1 promoter of hepatitis B virus, and to clone its coding sequence.

METHODS: Yeast one-hybrid system was employed to screen a human liver cDNA library using 3 copies of SP I core sequence as a bait, and one unknown gene was obtained. The coding sequence of the preS1 promoter of hepatitis B virus specific DNA-binding protein 1 (SBP I) was cloned by bioinformatics methods.

RESULTS: The coding sequence of SBP1 was cloned successfully.

CONCLUSION: SBP1 has a complete open reading frame, and biological functions by binding with SP I. The sequence similarity results indicate that the human SBP1 is a new member of transcription factor C/EBP.