Different modes of NF-kappaB/Rel activation in pancreatic lobules

The eukaryotic transcription factor nuclear factor-kappaB (NF-kappaB)/Rel is activated by a large variety of stimuli. It has been demonstrated that NF-kappaB/Rel is induced during the course of cerulein pancreatitis. Here, we show that NF-kappaB/Rel is differentially activated in pancreatic lobules. Cerulein induces NF-kappaB/Rel via activation of IkappaB kinase (IKK), which causes degradation of IkappaBalpha but not IkappaBbeta. Tumor necrosis factor-alpha-mediated IKK activation leads to IkappaBalpha and IkappaBbeta degradation. In contrast, oxidative stress induced by H(2)O(2) activates NF-kappaB/Rel independent of IKK activation and IkappaBalpha degradation; instead IkappaBalpha is phosphorylated on tyrosine. H(2)O(2) but not cerulein-mediated NF-kappaB/Rel activation can be blocked by stabilizing microtubules with Taxol. Inhibition of tubulin polymerization with nocodazole causes NF-kappaB/Rel activation in pancreatic lobules. These results propose three different pathways of NF-kappaB/Rel activation in pancreatic acinar cells. Furthermore, these data demonstrate that microtubules play a key role in IKK-independent NF-kappaB/Rel activation following oxidative stress.