title: Hyperglycemia stimulates p62/PKCζ interaction, which mediates NF-κB activation, increased Nox4 expression, and inflammatory cytokine activation in vascular smooth muscle.
abstract: Hyperglycemia leads to vascular smooth muscle cell (VSMC) dedifferentiation and enhances responses to IGF-I. Prior studies showed that hyperglycemia stimulated NADPH oxidase 4 (Nox4) synthesis, and IGF-I facilitated its recruitment to a signaling complex where it oxidized src, leading to AKT and MAPK activation. To determine the mechanism that led to these changes, we analyzed the roles of p62 (sequestrosome1) and PKCζ. Hyperglycemia induced a 4.9 ± 1.0-fold increase in p62/PKCζ association, and disruption of PKCζ/p62 using a peptide inhibitor or p62 knockdown reduced PKCζ activation (78 ± 6%). 3-Phosphoinoside-dependent protein kinase 1 was also recruited to the p62 complex and directly phosphorylated PKCζ, leading to its activation (3.1 ± 0.4-fold). Subsequently, activated PKCζ phosphorylated p65 rel, which led to increased Nox4 synthesis. Studies in diabetic mice confirmed these findings (6.0 ± 0.4-fold increase in p62/PKCζ) and their disruption of attenuated Nox4 synthesis (76 ± 9% reduction). PKCζ/p62 activation stimulated inflammatory cytokine production and enhanced IGF-I-stimulated VSMC proliferation. These results define the molecular mechanism by which PKCζ is activated in response to hyperglycemia and suggest that this could be a mechanism by which other stimuli such as cytokines or metabolic stress function to stimulate NF-κB activation, thereby altering VSMC sensitivity to IGF-I.
authors.affiliation: *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Xi
authors.affiliation: *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China.
authors.forename: Xinchun
authors.initials: X
authors.lastname: Shen
authors.affiliation: *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China.
authors.forename: Christine
authors.initials: C
authors.lastname: Wai
authors.affiliation: *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China.
authors.forename: Caroline K
authors.initials: CK
authors.lastname: Vilas
authors.affiliation: *Department of Medicine, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA; and College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, China david_clemmons@med.unc.edu.
authors.forename: David R
authors.initials: DR
authors.lastname: Clemmons
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D004789:Enzyme Activation; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006943:Hyperglycemia / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D000071456:Sequestosome-1 Protein; D013552:Swine; D000099221:Protein Kinase C zeta
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016207:Cytokines; D006360:Heat-Shock Proteins; D018836:Inflammation Mediators; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; D016328:NF-kappa B; D011493:Protein Kinase C; D000071456:Sequestosome-1 Protein; D000099221:Protein Kinase C zeta; C101343:Sqstm1 protein, mouse; C422943:Nox4 protein, mouse
keywords: IGF-I; PDK1; TNF-α; diabetes; p65 rel