T cell receptor-induced lipid raft recruitment of the I kappa B kinase complex is necessary and sufficient for NF-kappa B activation occurring in the cytosol.
TCR-induced NF-kappa B activation is necessary for the innate immune response and involves induced lipid raft recruitment of the I kappa B kinase (IKK) complex. In this study, we systematically investigated lipid raft recruitment of members of the NF-kappa B activation pathway in human T cells. All upstream components leading to IKK activation were found constitutively or inducibly in lipid rafts, while the NF-kappa B/I kappa B complex and phosphorylated forms of IKK alpha/beta, I kappa B alpha and p65 are exclusively found in the cytosolic fraction. Disruption of raft organization precluded NF-kappaB activation induced by T cell costimulation, but IL-1-triggered NF-kappa B activation remained unaffected. Targeting of the IKK complex to lipid rafts caused constitutive IKK activation and NF-kappa B DNA binding, which was further triggered upon T cell costimulation. Various experimental approaches revealed that costimulation-induced IKK alpha/beta activation loop phosphorylation is independent from IKK beta-mediated transautophosphorylation, but rather involves phosphorylation by the IKK-interacting protein NIK and its upstream activator COT.
Sebald
Andrea
A
University of Bern, Department of Chemistry and Biochemistry, Bern, Switzerland.
Mattioli
Ivan
I
Schmitz
M Lienhard
ML
D018106:CD28 Antigens / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D003600:Cytosol / Q000276:immunology / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D051550:I-kappa B Kinase; D007113:Immunity, Innate; D019169:Jurkat Cells; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D021962:Membrane Microdomains / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D000097782:NF-kappaB-Inducing Kinase
D018106:CD28 Antigens; D017252:CD3 Complex; D051550:I-kappa B Kinase; D020930:MAP Kinase Kinase Kinases; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D011948:Receptors, Antigen, T-Cell; D000097782:NF-kappaB-Inducing Kinase; C496559:CHUK protein, human; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C069937:MAP3K8 protein, human