title: The co-chaperone BAG3 interacts with the cytosolic chaperonin CCT: new hints for actin folding.
abstract: It has been recently hypothesized that BAG3 protein, a co-chaperone of Hsp70/Hsc70, is involved in the regulation of several cell processes, such as apoptosis, autophagy and cell motility. Following the identification of Hsc70/Hsp70, further BAG3 molecular partners such as PLC-gamma and HspB8 were likewise identified, thus contributing to the characterization of the mechanisms and the biological roles carried out by this versatile protein. By using a His-tagged BAG3 protein as bait, we fished out and identified the cytosolic chaperonin CCT, a new unreported BAG3 partner. The interaction between BAG3 and CCT was confirmed and characterized by co-immunoprecipitation experiments and surface plasmon resonance techniques. Furthermore, our analyses showed a slower CCT association and a faster dissociation with a truncated form of BAG3 containing the BAG domain, thus indicating that other protein regions are essential for a high-affinity interaction. ATP or ADP does not seem to significantly influence the chaperonin binding to BAG3 protein. On the other hand, our experiments showed that BAG3 silencing by small interfering RNA slowed down cell migration and influence the availability of correctly folded monomeric actin, analyzed by DNAse I binding assays and latrunculin A depolymerization studies. To our knowledge, this is the first report showing a biologically relevant interaction between the chaperonin CCT and BAG3 protein, thus suggesting interesting involvement in the folding processes regulated by CCT.
authors.affiliation: Department of Pharmaceutical Sciences, Division of Biomedicine Arturo Leone, University of Salerno, Salerno, Italy.
authors.forename: Bianca
authors.initials: B
authors.lastname: Fontanella
authors.forename: Leila
authors.initials: L
authors.lastname: Birolo
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Infusini
authors.forename: Claudia
authors.initials: C
authors.lastname: Cirulli
authors.forename: Liberato
authors.initials: L
authors.lastname: Marzullo
authors.forename: Pietro
authors.initials: P
authors.lastname: Pucci
authors.forename: Maria Caterina
authors.initials: MC
authors.lastname: Turco
authors.forename: Alessandra
authors.initials: A
authors.lastname: Tosco
mesh_terms: D000199:Actins / Q000737:chemistry*; D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins; D045744:Cell Line, Tumor; D002465:Cell Movement; D056404:Chaperonin Containing TCP-1 / Q000378:metabolism*; D003599:Cytoskeleton / Q000187:drug effects; D003850:Deoxyribonuclease I / Q000378:metabolism; D050883:HSC70 Heat-Shock Proteins / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D017510:Protein Folding; D054730:Protein Interaction Domains and Motifs; D034622:RNA Interference; D034741:RNA, Small Interfering; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D020349:Surface Plasmon Resonance; D053719:Tandem Mass Spectrometry
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C414431:BAG3 protein, human; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D003850:Deoxyribonuclease I; D056404:Chaperonin Containing TCP-1