MUC1 oncoprotein activates the IkappaB kinase beta complex and constitutive NF-kappaB signalling.
Nuclear factor-kappaB (NF-kappaB) is constitutively activated in diverse human malignancies by mechanisms that are not understood. The MUC1 oncoprotein is aberrantly overexpressed by most human carcinomas and, similarly to NF-kappaB, blocks apoptosis and induces transformation. This study demonstrates that overexpression of MUC1 in human carcinoma cells is associated with constitutive activation of NF-kappaB p65. We show that MUC1 interacts with the high-molecular-weight IkappaB kinase (IKK) complex in vivo and that the MUC1 cytoplasmic domain binds directly to IKKbeta and IKKgamma. Interaction of MUC1 with both IKKbeta and IKKgamma is necessary for IKKbeta activation, resulting in phosphorylation and degradation of IkappaBalpha. Studies in non-malignant epithelial cells show that MUC1 is recruited to the TNF-R1 complex and interacts with IKKbeta-IKKgamma in response to TNFalpha stimulation. TNFalpha-induced recruitment of MUC1 is dependent on TRADD and TRAF2, but not the death-domain kinase RIP1. In addition, MUC1-mediated activation of IKKbeta is dependent on TAK1 and TAB2. These findings indicate that MUC1 is important for physiological activation of IKKbeta and that overexpression of MUC1, as found in human cancers, confers sustained induction of the IKKbeta-NF-kappaB p65 pathway.
Ahmad
Rehan
R
Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA.
Raina
Deepak
D
Trivedi
Vishal
V
Ren
Jian
J
Rajabi
Hasan
H
Kharbanda
Surender
S
Kufe
Donald
D
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D002460:Cell Line; D004789:Enzyme Activation; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D018396:Mucin-1 / Q000502:physiology*; D010766:Phosphorylation; D011485:Protein Binding; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D015398:Signal Transduction; D047992:TNF Receptor-Associated Factor 2 / Q000378:metabolism; D051996:Transcription Factor RelA / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000099151:MAP Kinase Kinase Kinase 7
D048868:Adaptor Proteins, Signal Transducing; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D020930:MAP Kinase Kinase Kinases; D018396:Mucin-1; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; D047888:Receptors, Tumor Necrosis Factor, Type I; D047992:TNF Receptor-Associated Factor 2; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D000099151:MAP Kinase Kinase Kinase 7; C083487:I kappa B beta protein; C060192:MUC1 protein, human; C410585:TAB2 protein, human