Phosphorylation and ubiquitination of the IkappaB kinase complex by two distinct signaling pathways.
The IkappaB kinase (IKK) complex serves as the master regulator for the activation of NF-kappaB by various stimuli. It contains two catalytic subunits, IKKalpha and IKKbeta, and a regulatory subunit, IKKgamma/NEMO. The activation of IKK complex is dependent on the phosphorylation of IKKalpha/beta at its activation loop and the K63-linked ubiquitination of NEMO. However, the molecular mechanism by which these inducible modifications occur remains undefined. Here, we demonstrate that CARMA1, a key scaffold molecule, is essential to regulate NEMO ubiquitination upon T-cell receptor (TCR) stimulation. However, the phosphorylation of IKKalpha/beta activation loop is independent of CARMA1 or NEMO ubiquitination. Further, we provide evidence that TAK1 is activated and recruited to the synapses in a CARMA1-independent manner and mediate IKKalpha/beta phosphorylation. Thus, our study provides the biochemical and genetic evidence that phosphorylation of IKKalpha/beta and ubiquitination of NEMO are regulated by two distinct pathways upon TCR stimulation.
Shambharkar
Prashant B
PB
Department of Molecular and Cellular Oncology, University of Texas, M.D. Anderson Cancer Center, Houston, TX 77030, USA.
Blonska
Marzenna
M
Pappu
Bhanu P
BP
Li
Hongxiu
H
You
Yun
Y
Sakurai
Hiroaki
H
Darnay
Bryant G
BG
Hara
Hiromitsu
H
Penninger
Josef
J
Lin
Xin
X
D048868:Adaptor Proteins, Signal Transducing / Q000172:deficiency / Q000378:metabolism; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000172:deficiency / Q000378:metabolism; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053468:CARD Signaling Adaptor Proteins / Q000172:deficiency / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D051550:I-kappa B Kinase / Q000172:deficiency / Q000378:metabolism*; D019169:Jurkat Cells; D008239:Lysine / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism; D051379:Mice; D018448:Models, Immunological; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D021381:Protein Transport; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D013601:T-Lymphocytes / Q000201:enzymology; D025801:Ubiquitin / Q000378:metabolism*; D000099151:MAP Kinase Kinase Kinase 7
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053468:CARD Signaling Adaptor Proteins; D051550:I-kappa B Kinase; D008239:Lysine; D020930:MAP Kinase Kinase Kinases; D016328:NF-kappa B; D011493:Protein Kinase C; D011948:Receptors, Antigen, T-Cell; D025801:Ubiquitin; D000099151:MAP Kinase Kinase Kinase 7; C488088:Bcl10 protein, mouse; C496467:Card11 protein, mouse; C491731:IKBKG protein, human