title: Improved secretion of molecular chaperone-assisted human IgG in silkworm, and no alterations in their N-linked glycan structures.
abstract: Human 29IJ6 IgG was expressed in silkworm using a Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid system. The mean amounts of 296IJ6 IgG produced in larval hemolymph and whole pupae were 30.1 microg/larva and 78.0 microg/pupa, respectively. The use of molecular chaperones including calreticulin (CRT), calnexin (CNX), and immunoglobulin heavy chain binding protein (BiP, GRP78) improved the production of 296IJ6 IgG secretion in the larvae fivefold. The total yield of recombinant 29IJ6 IgG was 239 microg/mL when coexpressed with CRT. However, the overexpression of molecular chaperones had negative effects on secretion. The N-linked glycans of secreted 296IJ6 IgG in silkworm hemolymph were dominated by paucimannose structures. Small amounts of GlcNAc residues linked to the Manalpha1,3 branch were detected. When molecular chaperones were coexpressed, the compositions of N-linked glycans in the IgG1 produced were unchanged compared with those produced without them. This suggests that N-glycosylation is controlled by a regulatory function in the Golgi apparatus even though the post-translational modification of 296IJ6 IgG was assisted by the coexpression of molecular chaperones. Therefore, if the glycosylation pathways that coexpress N-acetylglucosaminyltransferase, galactosyltransferase, and sialyltransferase could be improved, silkworm larvae might prove a useful system for producing human antibodies.
authors.affiliation: Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Dojima
authors.forename: Takuya
authors.initials: T
authors.lastname: Nishina
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kato
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Uno
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Yagi
authors.forename: Koichi
authors.initials: K
authors.lastname: Kato
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueda
authors.forename: Enoch Y
authors.initials: EY
authors.lastname: Park
mesh_terms: D000818:Animals; D012831:Bombyx / Q000737:chemistry / Q000378:metabolism*; D037281:Calnexin / Q000096:biosynthesis / Q000737:chemistry; D037282:Calreticulin / Q000096:biosynthesis / Q000737:chemistry; D000091342:Endoplasmic Reticulum Chaperone BiP; D006056:Golgi Apparatus / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000737:chemistry; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis* / Q000737:chemistry; D018832:Molecular Chaperones / Q000096:biosynthesis* / Q000737:chemistry; D017924:Nucleopolyhedroviruses / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis
chemical_list: D037282:Calreticulin; D000091342:Endoplasmic Reticulum Chaperone BiP; C000717247:HSPA5 protein, human; D006360:Heat-Shock Proteins; D007074:Immunoglobulin G; D018832:Molecular Chaperones; D011134:Polysaccharides; D011994:Recombinant Proteins; D037281:Calnexin