NF-kappaB-inducing kinase restores defective IkappaB kinase activity and NF-kappaB signaling in intestinal epithelial cells.
Cytokine-stimulated IkappaBalpha degradation is impaired in HT-29 and primary intestinal epithelial cells. To gain more insight into the mechanism of this defect, we dissected cytokine-induced NF-kappaB signaling pathway in HT-29 cells. IL-1beta and TNF, alone or in combination with IFNgamma, failed to induce IkappaBalpha or IkappaBbeta degradation in HT-29 cells. Despite similar 125I-IL-1beta binding, HT-29 cells displayed no IRAK degradation, a 75% reduction of IKK activity, and decreased IkappaBalpha phosphorylation, NF-kappaB DNA binding activity and IL-8 mRNA accumulation in response to IL-1beta compared to Caco-2 cells. Selective activation of NF-kappaB pathway by adenoviral delivery of NF-kappaB-inducing kinase (Ad5NIK) or IKKbeta (Ad5IKKbeta) strongly activated IKK activity (>20 fold) in HT-29 cells with concomitant endogenous IkappaBalpha serine 32 phosphorylation and total IkappaBalpha degradation. In addition, NF-kappaB DNA binding activity and IL-8 secretion is higher in Ad5NIK-infected than in IL-1beta-stimulated HT-29 cells. These data show that altered NF-kappaB signaling is associated with impaired stimulation of an upstream IKK activator.
Russo
Maria Pia
MP
Department of Medicine, Division of Gastroenterology and Hepatology, CB #7032, Medical Biomolecular Research Building, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7080, USA.
Schwabe
Robert F
RF
Sartor
R Balfour
RB
Jobin
Christian
C
D000818:Animals; D018938:Caco-2 Cells; D016207:Cytokines / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000378:metabolism; D004847:Epithelial Cells / Q000201:enzymology*; D006801:Humans; D051550:I-kappa B Kinase; D053592:Interleukin-1 Receptor-Associated Kinases; D007422:Intestines / Q000201:enzymology; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014407:Tumor Cells, Cultured; D000097782:NF-kappaB-Inducing Kinase
D016207:Cytokines; D004268:DNA-Binding Proteins; D051550:I-kappa B Kinase; D053592:Interleukin-1 Receptor-Associated Kinases; D016328:NF-kappa B; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D012694:Serine; D000097782:NF-kappaB-Inducing Kinase; C496559:CHUK protein, human; C496560:IKBKB protein, human; C496565:IKBKE protein, human