title: Cell proliferation by silk gut incorporating FGF-2 protein microcrystals.
abstract: Silk gut processed from the silk glands of the silkworm could be an ideal biodegradable carrier for cell growth factors. We previously demonstrated that polyhedra, microcrystals of Cypovirus 1 polyhedrin, can serve as versatile carrier proteins. Here, we report the generation of a transgenic silkworm that expresses polyhedrin together with human basic fibroblast growth factor (FGF-2) in its posterior silk glands to utilize silk gut as a proteinaceous carrier to protect and slowly release active cell growth factors. In the posterior silk glands, polyhedrin formed polyhedral microcrystals, and FGF-2 became encapsulated within the polyhedra due to a polyhedron-immobilization signal. Silk gut powder prepared from posterior silk glands containing polyhedron-encapsulated FGF-2 stimulated the phosphorylation of p44/p42 MAP kinase and induced the proliferation of serum-starved NIH3T3 cells by releasing bioactive FGF-2. Even after a one-week incubation at 25 °C, significantly higher biological activity of FGF-2 was observed for silk gut powder incorporating polyhedron-encapsulated FGF-2 relative to silk gut powder with non-encapsulated FGF-2. Our results demonstrate that posterior silk glands incorporating polyhedron-encapsulated FGF-2 are applicable to the preparation of biodegradable silk gut, which can protect and release FGF-2 that is produced in a virus- and serum-free expression system with significant application potential.
authors.affiliation: 1] Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan [2] Insect Biomedical Centre, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Kotani
authors.affiliation: Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Kobayashi
authors.affiliation: Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Keiro
authors.initials: K
authors.lastname: Uchino
authors.affiliation: Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Muto
authors.affiliation: Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ijiri
authors.affiliation: Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Shimabukuro
authors.affiliation: Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Tamura
authors.affiliation: Transgenic Silkworm Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Sezutsu
authors.affiliation: 1] Department of Applied Biology, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan [2] Insect Biomedical Centre, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Mori
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D012831:Bombyx / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D004337:Drug Carriers / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D015870:Gene Expression / Q000235:genetics; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D041681:NIH 3T3 Cells; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D012087:Reoviridae / Q000378:metabolism; D047011:Silk / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D004337:Drug Carriers; D010446:Peptide Fragments; D047011:Silk; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; C503486:WDR77 protein, mouse; D016222:Fibroblast Growth Factor 2; D019950:Mitogen-Activated Protein Kinase 1