title: PKC-zeta-associated CK2 participates in the turnover of free IkappaBalpha.
abstract: The atypical PKC isoenzymes, zeta and iota, activate NF-kappaB, a mechanism thought to mediate the anti-apoptotic and proliferative features of these kinases. PKC-zeta has been shown to be associated with an IkappaBalpha kinase in resting cells. In this study, we have sought to identify the PKC-zeta associated kinase and understand how PKC-zeta mediates basal IkappaBalpha turnover in vivo. We demonstrate that the PKC-zeta-associated IkappaBalpha kinase is CK2. This kinase, previously shown to phosphorylate the PEST domain of IkappaB molecules, co-precipitates with PKC-zeta in resting cells. In vitro, PKC-zeta interacts with CK2-beta. The in vivo PKC-zeta-associated CK2 preferentially phosphorylates S293 of IkappaBalpha as compared to non-associated CK2. The functional relevance of this observation is supported by the fact that the turnover of free IkappaBalpha in resting cells is S293-dependent. Moreover, overexpressing PKC-zeta results in lower steady-state protein levels of free IkappaBalpha, which is dependent on S293. Lastly, it is shown that PKC-zeta wt but not kinase dead leads to the in vitro phosphorylation of both CK2-alpha and beta. These studies demonstrate that the association between CK2 and PKC-zeta may play a major role in the control of the basal turnover of free IkappaBalpha, in the absence of extracellular stimuli.
authors.affiliation: Department of Immunology, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: G D
authors.initials: GD
authors.lastname: Bren
authors.forename: K N
authors.initials: KN
authors.lastname: Pennington
authors.forename: C V
authors.initials: CV
authors.lastname: Paya
mesh_terms: D000818:Animals; D047390:Casein Kinase II; D020134:Catalytic Domain; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D017930:Genes, Reporter / Q000235:genetics; D006207:Half-Life; D006493:Heparin / Q000378:metabolism; D020035:Holoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D020672:I-kappa B Proteins; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D000072000:NF-KappaB Inhibitor alpha; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019893:Ribosomal Protein S6 Kinases / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D000099221:Protein Kinase C zeta
chemical_list: D047390:Casein Kinase II; D004268:DNA-Binding Proteins; D006493:Heparin; D020035:Holoenzymes; D020672:I-kappa B Proteins; D007527:Isoenzymes; D000072000:NF-KappaB Inhibitor alpha; D010768:Phosphoserine; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011993:Recombinant Fusion Proteins; D019893:Ribosomal Protein S6 Kinases; D000099221:Protein Kinase C zeta; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse