Transfection of N-acetylglucosaminyltransferase III gene suppresses expression of hepatitis B virus in a human hepatoma cell line, HB611.
beta-D-mannoside beta-1,4-N-acetylglucosaminyltransferase III (GnT-III) catalyzes the addition of N-acetylglucosamine in beta 1-4 linkage to the beta-linked mannose of the trimannosyl core of N-linked oligosaccharides and forms a bisecting GlcNAc structure. Although the biological meaning of the bisecting GlcNAc structure remains unclear, it is known that the attachment of a bisecting GlcNAc inhibits further processing of oligosaccharides by other glycosyltransferases. To investigate whether or not structural changes of oligosaccharides affect secretion and gene expression of hepatitis B virus (HBV), we introduced the GnT-III gene into a human hepatoma cell line, HB611, which secreted HBV-related proteins into the medium. Positive transfectants were cloned by hygromycin resistant selection. Three clones have high activities of GnT-III and secreted lower levels of HBV-related proteins into the medium in comparison with other clones. These clones showed marked suppression of HBV-related mRNAs and an increased binding with E-PHA as judged by lectin blot. Expression of beta actin, alpha fetoprotein, albumin, and prealubmin was not correlated with GnT-III activity in all the seven clones. Treatment of these cells with tunicamycin or swainsonine resulted in enhanced expression of HBV-related mRNA. These results indicate that some glycoproteins whose oligosaccharide structures are changed by over-expression of GnT-III suppress HBV gene expression.
D015152:Blotting, Northern; D006528:Carcinoma, Hepatocellular; D002460:Cell Line; D005434:Flow Cytometry; D016695:Glycosyltransferases / Q000378:metabolism*; D006515:Hepatitis B virus / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D037102:Lectins; D008113:Liver Neoplasms; D017351:N-Acetylglucosaminyltransferases / Q000096:biosynthesis / Q000378:metabolism*; D009844:Oligosaccharides / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D012367:RNA, Viral / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014764:Viral Proteins / Q000096:biosynthesis*
D037102:Lectins; D009844:Oligosaccharides; D012333:RNA, Messenger; D012367:RNA, Viral; D011994:Recombinant Proteins; D014764:Viral Proteins; D016695:Glycosyltransferases; D017351:N-Acetylglucosaminyltransferases; C054599:beta-1,4-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase