title: Characterization of Novel Insulin Fibrils That Show Strong Cytotoxicity Under Physiological pH.
abstract: Amyloid fibrils are β-sheet-rich protein aggregates that are associated with more than 20 diseases. Insulin is known to form amyloid fibrils under a variety of conditions in vitro. Insulin fibrillations have been generally performed under acidic conditions, which are conducive to the formation of fibrils. As insulin is found almost exclusively as a monomer in acidic solutions, insulin fibrillation under acidic conditions is proposed to occur via its monomer. However, insulin fibrils, which cause injection-localized amyloidosis, form under neutral pH conditions in vivo, because both subcutaneous tissue and almost all insulin formulations maintain a neutral pH. In this study, we induced fibrillation under conditions more closely resembling physiological conditions than those used in previous studies with the aim of better understanding the nature of injection-localized amyloidosis in vivo. The results of transmission electron microscopy, structural analyses, and MTT assay show that the fibrils formed under conditions more closely resembling physiological conditions have different properties from the fibrils described to date. The results of this study indicate that fibrils formed under conditions more closely resembling physiological conditions have different properties from insulin fibrils induced under the conditions reported in previous studies.
authors.affiliation: Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata, 956-8603, Japan.
authors.forename: Hiromu
authors.initials: H
authors.lastname: Yoshihara
authors.affiliation: Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata, 956-8603, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Saito
authors.affiliation: Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata, 956-8603, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Tanabe
authors.affiliation: Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata, 956-8603, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Amada
authors.affiliation: Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata, 956-8603, Japan.
authors.forename: Toshinari
authors.initials: T
authors.lastname: Asakura
authors.affiliation: Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata, 956-8603, Japan.
authors.forename: Kouki
authors.initials: K
authors.lastname: Kitagawa
authors.affiliation: Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata, 956-8603, Japan. Electronic address: asada@nupals.ac.jp.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Asada
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry* / Q000633:toxicity* / Q000648:ultrastructure; D000818:Animals; D002470:Cell Survival; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000737:chemistry* / Q000633:toxicity*; D016716:PC12 Cells; D066329:Protein Aggregates; D011487:Protein Conformation; D051381:Rats; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000682:Amyloid; D007328:Insulin; D066329:Protein Aggregates
keywords: FTIR; morphology; peptide; protein; protein aggregation; protein formulation; protein structure; self-assembly; stability; toxicity