Background: In our previous study, a novel liver-targeting interferon (IFN-CSP) combining
IFN α2b with plasmodium region I-plus peptide was successfully designed and prepared with Escherichia
coli expression systems. The purified IFN-CSP showed anti-HBV activity and liver-targeting
potentiality. The present investigation was designed to investigate the molecular mechanisms responsible
for liver-targeting of IFN-CSP.
Methods: The binding site of IFN-CSP in hepatocytes was assayed by immunofluorescent staining. The correspondence
of HSPG distribution and the pattern of IFN-CSP binding in liver tissue were determined using a confocal laser scanning
microscope. Both the hepatocytes and liver tissue were using as model to investigate the effect of enzyme and soluble glycosaminoglycan
on IFN-CSP binding using flow cytometry and fluorescence microscope.
Results: Studies of hepatocytes demonstrated that the localization of IFN-CSP in hepatocytes was the plasma membrane.
Studies of liver tissue slices showed that IFN-CSP bound to liver tissue in a pattern similar to the distribution of heparan
sulfate proteoglycan (HSPG) immunoreactivity. Pretreatment of hepatocytes and liver slices with heparinase reduced the
binding of IFN-CSP to HepG2.2.15 cells and liver slices. Coincubation of IFN-CSP with heparin markedly inhibited IFNCSP
binding to HepG2.2.15 cells and liver slices.
Conclusion: These results indicate that the molecular mechanisms responsible for IFN-CSP targeting involve binding to
HSPG of hepatocytes and liver.