title: BETA2/NeuroD protein can be transduced into cells due to an arginine- and lysine-rich sequence.
abstract: BETA2/NeuroD, a basic helix-loop-helix transcription factor, is a key regulator of pancreatic islet morphogenesis and insulin gene transcription. Here we report for the first time that the BETA2/NeuroD protein can permeate several cells, including pancreatic islets, due to an arginine- and lysine-rich protein transduction domain sequence in its structure. The BETA2/NeuroD protein was transduced in a dose-dependent manner up to 1 micromol/l. Transduced BETA2/NeuroD functions similarly to endogenous BETA2/NeuroD: it binds to the insulin promoter and activates its expression. We also investigated the mechanism of BETA2/NeuroD protein transduction. The BETA2/NeuroD protein penetrated cells by macropinocytosis and was released from endosomes homogeneously in cytoplasm and nuclei. These data suggest that BETA2/NeuroD protein transduction could be a safe and valuable strategy for enhancing insulin gene transcription without requiring gene transfer technology.
authors.affiliation: Dept. of Transplantation and Immunology, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto 606-8507, Japan. noguchih@kuhp.kyoto-u.ac.jp
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Noguchi
authors.forename: Susan
authors.initials: S
authors.lastname: Bonner-Weir
authors.forename: Fan-Yan
authors.initials: FY
authors.lastname: Wei
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsushita
authors.forename: Shinichi
authors.initials: S
authors.lastname: Matsumoto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine; D051792:Basic Helix-Loop-Helix Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004705:Endocytosis; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007515:Islets of Langerhans / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008239:Lysine; D008297:Male; D021962:Membrane Microdomains / Q000502:physiology; D008969:Molecular Sequence Data; D010587:Phagocytosis; D010873:Pinocytosis; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D014162:Transfection
chemical_list: D001120:Arginine; D051792:Basic Helix-Loop-Helix Proteins; D049452:Green Fluorescent Proteins; D008239:Lysine; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; C093970:NEUROD1 protein, human; C485184:enhanced green fluorescent protein