title: Intracellular trafficking of bio-nanocapsule-liposome complex: Identification of fusogenic activity in the pre-S1 region of hepatitis B virus surface antigen L protein.
abstract: Bio-nanocapsules (BNCs) are a hollow nanoparticle consisting of about 100-nm liposome (LP) embedding about 110 molecules of hepatitis B virus (HBV) surface antigen (HBsAg) L protein as a transmembrane protein. Owing to the human hepatocyte-recognizing domains on the N-terminal region (pre-S1 region), BNCs have recently been shown to attach and enter into human hepatic cells using the early infection mechanism of HBV. Since BNCs could form a complex with an LP containing various drugs and genes, BNC-LP complexes have been used as a human hepatic cell-specific drug and gene-delivery system in vitro and in vivo. However, the role of BNCs in cell entry and intracellular trafficking of payloads in BNC-LP complexes has not been fully elucidated. In this study, we demonstrate that low pH-dependent fusogenic activity resides in the N-terminal part of pre-S1 region (NPLGFFPDHQLDPAFG), of which the first FF residues are essential for the activity, and which facilitates membrane fusion between LPs in vitro. Moreover, BNC-LP complexes can bind human hepatic cells specifically, enter into the cells via clathrin-mediated endocytosis, and release their payloads mostly into the cytoplasm. Taken together, the BNC portion of BNC-LP complexes can induce membrane fusion between LPs and endosomal membranes under low pH conditions, and thereby facilitate the endosomal escape of payloads. Furthermore, the fusogenic domain of the pre-S1 region of HBsAg L protein may play a pivotal role in the intracellular trafficking of not only BNC-LP complexes but also of HBV.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; Japan Society for the Promotion of Science, Tokyo 102-0083, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Somiya
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Sasaki
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsuzaki
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; The Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan.
authors.forename: Qiushi
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Iijima
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Nobuo
authors.initials: N
authors.lastname: Yoshimoto
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Niimi
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
authors.forename: Andrés Daniel
authors.initials: AD
authors.lastname: Maturana
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; The Institute of Scientific and Industrial Research, Osaka University, Osaka 567-0047, Japan. Electronic address: skuroda@sanken.osaka-u.ac.jp.
authors.forename: Shun'ichi
authors.initials: S
authors.lastname: Kuroda
mesh_terms: D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D004705:Endocytosis; D006801:Humans; D008081:Liposomes; D051379:Mice; D053769:Nanocapsules / Q000008:administration & dosage*; D012441:Saccharomyces cerevisiae; D014759:Viral Envelope Proteins / Q000737:chemistry*
chemical_list: C096362:L protein, hepatitis B virus; D008081:Liposomes; D053769:Nanocapsules; D014759:Viral Envelope Proteins
keywords: Bio-nanocapsules; Drug delivery; Endosomal escape; Fusogenic activity; Hepatitis B virus surface antigen; Liposomes