title: Involvement of kinase PKC-zeta in the p62/p62(P392L)-driven activation of NF-κB in human osteoclasts.
abstract: Mutations of the gene encoding sequestosome1 (SQSTM1/p62), clustering in or near the UBA domain, have been described in Paget's disease of bone (PDB); among these the P392L substitution is the most prevalent. Protein p62 mediates several cell functions, including the control of NF-κB signaling, and autophagy. This scaffolding protein interacts with atypical PKCζ in the RANKL-induced signaling complex. We have previously shown that osteoclasts (OCs) overexpressing the p62(P392L) variant were in a constitutively activated state, presenting activated kinase p-PKCζ/λ and activated NF-κB prior to RANKL stimulation. In the present study, we investigated the relationships between PKCζ and NF-κB activation in human OCs transfected with p62 variants. We showed that PKCζ and p-PKCζ/λ co-localize with p62, and that PKCζ is involved in the RANKL-induced NF-κB activation and in the RANKL-independent activation of NF-κB observed in p62(P392L)-transfected cells. We also observed a basal and RANKL-induced increase in IκBα levels in the presence of the p62(P392L) mutation that contrasted with the NF-κB activation. In this study we propose that PKCζ plays a role in the activation of NF-κB by acting as a p65 (RelA) kinase at Ser(536), independently of IκBα; this alternative pathway could be used preferentially in the presence of the p62(P392L) mutation, which may hinder the ubiquitin-proteasome pathway. Overall, our results highlight the importance of p62-associated PKCζ in the overactive state of pagetic OCs and in the activation of NF-κB, particularly in the presence of the p62(P392L) mutation.
authors.affiliation: University of Sherbrooke, Sherbrooke, PQ, Canada.
authors.forename: Estelle
authors.initials: E
authors.lastname: Chamoux
authors.forename: Stephen
authors.initials: S
authors.lastname: McManus
authors.forename: Gino
authors.initials: G
authors.lastname: Laberge
authors.forename: Martine
authors.initials: M
authors.lastname: Bisson
authors.forename: Sophie
authors.initials: S
authors.lastname: Roux
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D020672:I-kappa B Proteins / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D053245:RANK Ligand / Q000494:pharmacology; D000071456:Sequestosome-1 Protein; D014162:Transfection; D019892:eIF-2 Kinase / Q000378:metabolism; D000099293:Protein Kinase C-lambda; D000099221:Protein Kinase C zeta
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D007527:Isoenzymes; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D011493:Protein Kinase C; D053245:RANK Ligand; D000071456:Sequestosome-1 Protein; D019892:eIF-2 Kinase; D000099293:Protein Kinase C-lambda; D000099221:Protein Kinase C zeta; C000606204:NFKBIA protein, human; C099718:SQSTM1 protein, human