Mechanism Of HBV Inhibiting SIAH1 Regulation Of PEG10 Expression

Hepatitis B virus(HBV)is a double-stranded hepadnavirus.Long-term infection with HBV will lead to cirrhosis,hepatitis and even the development of liver cancer.Although there are vaccines and drugs for HBV,which have certain preventive and therapeutic effects on HBV infection and diseases,the pathogenesis of HBV is still unclear,and the existing antiviral drugs against HBV are highly toxic.It is expensive or has a long treatment period.Therefore,the specific pathogenesis of HBV remains to be discovered.PEG10(Paternally Expressed 10)is a paternal imprinted gene that is highly expressed in a variety of cancer cells.It has been shown that HBV significantly upregulates the expression of PEG10 in hepatoma cells,and PEG10 promotes the proliferation and migration of hepatoma cells by activating NF-?B signaling pathway.The specific mechanism of HBV regulation of PEG10 is still unclear.Previous studies have shown that PEG10 interacts with SIAH1(Seven In Absentia Homolog 1),thereby inhibiting the proapoptotic effect of SIAH1 in hepatoma cells.SIAH1 is an E3 ubiquitin ligase that binds to a variety of proteins and mediates their degradation by the ubiquitin-proteasome pathway,thereby regulating cell proliferation,apoptosis,DNA damage repair,hypoxia,hormone regulation,etc.In the present study,we transiently transduced the HBV plasmid in the hepatoma cell line Huh7 and found that the protein and mRNA levels of SIAH1 were significantly decreased.In the hepatoma cell line HepG2 and HepG2.2.15 cells containing the HBV genome,SIAH1 was in the cell with HBV genome.Significantly lower than that without HBV;SIAH1 interacted with the PRALVLP motif of PEG10 RF1 without interaction with PEG10 RF2 by immunoprecipitation experiments;and overexpression of SIAH1 significantly inhibited the expression of PEG10,knocking down SIAH1 The expression level of PEG10 was significantly increased;we found that SIAH1 acts as an E3 ubiquitin ligase of PEG10,which mainly promotes the ubiquitination of K48 type,mediating its entry into the proteasome degradation pathway,thereby reducing PEG10.The expression level,the 249 lysine next to the binding motif is the site where PEG10 is ubiquitinated by SIAH1;while the SIAH1 enzyme active site is mutated,this inhibition is clearly restored;in vitro ubiquitination In experiments,the ubiquitination of PEG10 by SIAH1 was further verified.Our results provide clues to further understanding the relationship between HBV and host proteins,and to find potential drug targets for the corresponding clinical drugs SIAH1.