title: Identification and characterization of PKCγ, a kinase associated with SCA14, as an amyloidogenic protein.
abstract: Amyloid assemblies are associated with a wide range of human disorders, including Alzheimer's and Parkinson's diseases. Here, we identify protein kinase C (PKC) γ, a serine/threonine kinase mutated in the neurodegenerative disease spinocerebellar ataxia type 14 (SCA14), as a novel amyloidogenic protein with no previously characterized amyloid-prone domains. We found that overexpression of PKCγ in cultured cells, as well as in vitro incubation of PKCγ without heat or chemical denaturants, causes amyloid-like fibril formation of this protein. We also observed that SCA14-associated mutations in PKCγ accelerate the amyloid-like fibril formation both in cultured cells and in vitro. We show that the C1A and kinase domains of PKCγ are involved in its soluble dimer and aggregate formation and that SCA14-associated mutations in the C1 domain cause its misfolding and aggregation. Furthermore, long-term time-lapse imaging indicates that aggregates of mutant PKCγ are highly toxic to neuronal cells. Based on these findings, we propose that PKCγ could form amyloid-like fibrils in physiological and/or pathophysiological conditions such as SCA14. More generally, our results provide novel insights into the mechanism of amyloid-like fibril formation by multi-domain proteins.
authors.affiliation: Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Takahashi
authors.affiliation: Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Adachi
authors.affiliation: Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Shirafuji
authors.affiliation: Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
authors.forename: Sally
authors.initials: S
authors.lastname: Danno
authors.affiliation: Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
authors.forename: Takehiko
authors.initials: T
authors.lastname: Ueyama
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
authors.forename: Michele
authors.initials: M
authors.lastname: Vendruscolo
authors.affiliation: Department of Neurophysiology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Anton N
authors.initials: AN
authors.lastname: Shuvaev
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Sugimoto
authors.affiliation: Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto 862-0973, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Seki
authors.affiliation: Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Kobe University, Kobe 650-0017, Japan and.
authors.forename: Daizo
authors.initials: D
authors.lastname: Hamada
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Irie
authors.affiliation: Department of Neurophysiology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Hirai
authors.affiliation: Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical Science, Hiroshima University, Hiroshima 734-8551, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Sakai
authors.affiliation: Biosignal Research Center, Kobe University, Kobe 657-8501, Japan naosaito@kobe-u.ac.jp.
authors.forename: Naoaki
authors.initials: N
authors.lastname: Saito
mesh_terms: D000682:Amyloid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D011485:Protein Binding; D011493:Protein Kinase C / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D020754:Spinocerebellar Ataxias; D013132:Spinocerebellar Degenerations / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D000682:Amyloid; C087857:protein kinase C gamma; D011493:Protein Kinase C