Cellular differentiation causes a selective down-regulation of interleukin (IL)-1beta-mediated NF-kappaB activation and IL-8 gene expression in intestinal epithelial cells.
Interleukin (IL)-1beta signals through various adapter proteins and kinases that lead to activation of numerous downstream targets, including the transcription factors including NF-kappaB. In this study, we analyzed and characterized the effect of the differentiation of intestinal epithelial cells on IL-1beta-mediated NF-kappaB activation and IL-8 gene expression. We report that IL-8 mRNA accumulation and protein secretion were down-regulated in IL-1beta- and lipopolysaccharide-stimulated differentiated HT-29 cells (HT-29/MTX, where MTX is methotrexate) compared with undifferentiated cells (HT-29/p), whereas no differential effects were found following tumor necrosis factor (TNF)-alpha or phorbol myristate acetate stimulation. Cross-linking and affinity binding studies reveal that IL-1beta exclusively binds the type I receptor (IL-1RI) and not IL-1RII in both HT-29/p and HT-29/MTX cells. IL-1beta-mediated IkappaB kinase and c-Jun N-terminal kinase (JNK) activity were both diminished in differentiated HT-29 cells. DNA binding activity in differentiated HT-29 cells relative to HT-29/p cells was strongly reduced following IL-1beta exposure but not after TNF-alpha stimulation. The proximal IL-1 signaling molecule IL-1 receptor-associated kinase was not degraded in IL-1beta-stimulated HT-29 cells, in contrast to Caco-2 cells. kappaB-luciferase reporter gene activity was 16-fold higher following TNF receptor-associated factor-6 transfection after IL-1beta stimulation in HT-29/MTX cells. We conclude that cellular differentiation of HT-29 cells selectively impairs the IL-1beta signaling pathway inhibiting both NF-kappaB and JNK activity in response to IL-1beta. This relative unresponsiveness to IL-1beta may represent an important regulatory mechanism of differentiated intestinal epithelial cells.
Böcker
U
U
Center for Gastrointestinal Biology and Disease, Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7080, USA.
Schottelius
A
A
Watson
J M
JM
Holt
L
L
Licato
L L
LL
Brenner
D A
DA
Sartor
R B
RB
Jobin
C
C
D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D006801:Humans; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000378:metabolism*; D053592:Interleukin-1 Receptor-Associated Kinases; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism*; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000378:metabolism; D011506:Proteins / Q000235:genetics; D017472:Receptors, Interleukin-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D012795:Sialoglycoproteins / Q000008:administration & dosage / Q000494:pharmacology; D015398:Signal Transduction; D048029:TNF Receptor-Associated Factor 6
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D011506:Proteins; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; D048029:TNF Receptor-Associated Factor 6; D011494:Protein Kinases; D053592:Interleukin-1 Receptor-Associated Kinases