title: PKCα binds G3BP2 and regulates stress granule formation following cellular stress.
abstract: Protein kinase C (PKC) isoforms regulate a number of processes crucial for the fate of a cell. In this study we identify previously unrecognized interaction partners of PKCα and a novel role for PKCα in the regulation of stress granule formation during cellular stress. Three RNA-binding proteins, cytoplasmic poly(A)(+) binding protein (PABPC1), IGF-II mRNA binding protein 3 (IGF2BP3), and RasGAP binding protein 2 (G3BP2) all co-precipitate with PKCα. RNase treatment abolished the association with IGF2BP3 and PABPC1 whereas the PKCα-G3BP2 interaction was largely resistant to this. Furthermore, interactions between recombinant PKCα and G3BP2 indicated that the interaction is direct and PKCα can phosphorylate G3BP2 in vitro. The binding is mediated via the regulatory domain of PKCα and the C-terminal RNA-binding domain of G3BP2. Both proteins relocate to and co-localize in stress granules, but not to P-bodies, when cells are subjected to stress. Heat shock-induced stress granule assembly and phosphorylation of eIF2α are suppressed following downregulation of PKCα by siRNA. In conclusion this study identifies novel interaction partners of PKCα and a novel role for PKCα in regulation of stress granules.
authors.affiliation: Center for Molecular Pathology, Lund University, Malmö, Sweden.
authors.forename: Tamae
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Sofia
authors.initials: S
authors.lastname: Winslow
authors.forename: Lovisa
authors.initials: L
authors.lastname: Sunesson
authors.forename: Ulf
authors.initials: U
authors.lastname: Hellman
authors.forename: Christer
authors.initials: C
authors.lastname: Larsson
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D003594:Cytoplasmic Granules / Q000201:enzymology* / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D055785:Gene Knockdown Techniques; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018869:Heat-Shock Response; D006801:Humans; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D039122:Poly(A)-Binding Protein I / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D051571:Protein Kinase C-alpha / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D034622:RNA Interference; D016601:RNA-Binding Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013312:Stress, Physiological
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D015852:Eukaryotic Initiation Factor-2; C574606:G3BP2 protein, human; C498780:IGF2BP3 protein, human; D010446:Peptide Fragments; D039122:Poly(A)-Binding Protein I; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D051571:Protein Kinase C-alpha