[Study on a putative, proprotein convertase-cleaved product of HBV core protein in vitro].
OBJECTIVE
To investigate the cleavage of HBV core protein in vivo by proprotein convertase furin or its family members and observe the intracellular localization of the putative cleaved product.


METHODS
Recombinant HBV core protein was incubated with furin under different conditions in vitro, and the reaction was checked with Western blotting. The recombinant vectors expressed the putative cleaved fragment and intact core protein (serves as control) were constructed. The stable expression cell lines were established by transfecting constructs into HepG2 cell line, for which indirect immunofluorescence staining was used by monoclonal anti-HBc against the region shared by core protein and its cleaved product .The confocal microscopy was carried out to observe the intracellular distribution.


RESULTS
HBV core protein was cleaved by furin in vitro under different tested conditions. The molecular weight of the major cleaved product just about 15,000 was in concordance with the expectation. The expressed cleaved fragment could react to the monoclonal antibody against core protein, and mainly located in cytosol in particle style just like the intact core protein.


CONCLUSIONS
HBV core protein can be cleaved by furin in vitro. The major cleaved product has similar antigenicity and subcellular distribution to core protein. These data suggest that proprotein convertase furin or its family members play important roles in HBV replication regulation, and the cleaved product may be involved in antiviral immunity of HBV infection. Further investigations are imperative.
Cheng
Jie
J
Guangzhou NO.8 Peoples Hospital, and Sun Yat-Sen University, Guangzhou 510060, China.
Shi
Hong
H
Lei
Rui-xiang
RX
Peng
Xiao-mou
XM
D045683:Furin / Q000378:metabolism*; D005822:Genetic Vectors; D056945:Hep G2 Cells; D006512:Hepatitis B Core Antigens / Q000378:metabolism*; D006515:Hepatitis B virus / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D042282:Microdissection; D018613:Microscopy, Confocal; D043484:Proprotein Convertases / Q000378:metabolism*; D014162:Transfection; D014779:Virus Replication
D006512:Hepatitis B Core Antigens; D043484:Proprotein Convertases; D045683:Furin