Title: EGF enhances the mitogenic effects of IGF-I in intestinal epithelial cells by regulating multiple steps in the IGF-I signaling pathway
Abstract: of IL-8 mRNA.This synergy was IL-8 specific, since TNF-oLinduced claudin-2 mRNA expression was inhibited in the presence of MG-132.Neither MG-132 nor lactacystin decreased NF-KB binding activity induced by TNF-o~.In contrast, MG-132, but not lactacystin induced a caspase-3 dependent activation of NF-KB, which correlated with an increase of p65 and IKB/~, but decrease of IKB~ expression.In addition, MG-132 induced the strong activation of ERK1/2-, p38-and JNK1/2-MAP-Kinases.However, prevention of NF-KB activation with the caspase-3 inhibitor zDEVD-FMK, inhibition of p38 with SB203580 or ERK activation with PD98059, did not prevent MG-132 induced IL-8 mRNA expression.Instead, the activation of JNK1/2 by MG-132 resulted in the phosphorylation of c-Jun and the subsequent activation AP-1 consensus binding activity.Conclusions: IL-8 mRNA expression can be regulated independently of NF-KB, ERK-, and p38-MAP-Kinases in T-84 cells.MG-132 can act as a strong inducer of IL-8 mRNA expression, independent of its function as proteosome inhibitor or activator of caspase-3.MG-132 induced IL-8 mRNA expression may involve JNK1/2 dependent AP-1 activation and mRNA stabilization by a p38 independent pathway.
Publication Year: 2001
Publication Date: 2001-04-01
Language: en
Type: article
Indexed In: ['crossref']
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