Expression of APOBEC3G induced by interferonalpha in HepG2 2.2.15 cells

Abstract:

    ObjectiveTo study the effects of interferonalpha (IFNα) on apolipoprotein B mRNAediting enzyme catalytic polypeptidelike 3G （APOBEC3G） expression by stimulating HepG2 2.2.15 cells with IFNα, and to preliminarily investigate whether Janus kinasesignal transduction and activators of transcription (JAKSTAT) signal pathway participates in the regulation of APOBEC3G gene transcription. MethodsHepG2 2.2.15 cells were treated with various concentrations of IFNα (0, 1, 101, 102, 103, 104 U/mL) for 8 hours, or with IFNα of 103 U/mL for 2, 4, 6, 8, 10, 12 hours. In the abovementioned time, cells or cultural supernatants were collected. The mRNA and protein expression levels of APOBEC3G and STAT1 in HepG2 2.2.15 cells were detected by realtime fluorescent quantitation RTPCR and Westernblot respectively. The levels of HBsAg and HBeAg in the cultural supernatant of HepG2 2.2.15 cells were detected by ELISA. The levels of HBV DNA in supernatant and HBV mRNA in cells were determined by realtime PCR and RTPCR respectively. ResultsThe expression level of APOBEC3G was very low in HepG2 2.2.15 cells untreated with IFNα (0 U/mL). With the rising of IFNα concentration, APOBEC3G mRNA and protein level rose progressively. When IFNα concentration was 104 U/mL, the expression level of APOBEC3G was the highest. Moreover, the expression level of STAT1 mRNA and protein also rose progressively, which appeared with APOBEC3G expression amount parallelly and relevantly. With the extension of time with IFNα stimulation, APOBEC3G expression level rose obviously, which reached the highest at the 8 hours, and thereafter dropped gradually. When IFNα of 104 U/mL stimulated 8 hours, the level of HBsAg, HBeAg, HBV DNA in cultural supernatant and the level of HBV mRNA in HepG2 2.2.15 cells were obviously lower than the cells untreated with IFNα. ConclusionIFNα can induce HepG2 2.2.15 cells to express APOBEC3G. Within the certain limits, APOBEC3G expression presents positive correlation with IFNα dosage and action time. The expression of APOBEC3G induced by IFNα may be one of antiviral mechanisms of IFNα. Whether JAKSTAT signal pathway participates in the expression of APOBEC3G induced by IFNα need further study.