Neurotensin stimulates interleukin-8 expression through modulation of I kappa B alpha phosphorylation and p65 transcriptional activity: involvement of protein kinase C alpha.
Neurotensin (NT) is released in the gastrointestinal tract and participates in the pathophysiology of colonic inflammation. We have shown that NT mediates acute intestinal inflammation in vivo and stimulates nuclear factor-kappaB-dependent interleukin (IL)-8 expression in nontransformed human colonocytes in vitro. However, the exact mechanisms by which NT induces IL-8 expression have not been elucidated. In this study, we first show that NT stimulates IkappaBalpha phosphorylation and degradation and p65 phosphorylation and transcriptional activity. Inhibition of protein kinase C (PKC) activation significantly attenuates NT-induced IL-8 expression. This effect seems to be mediated through inhibition of IkappaBalpha phosphorylation and degradation and by p65 phosphorylation and transcriptional activity. We also show that intracellular calcium mobilization is necessary for NT-induced phosphorylation of IkappaBalpha and p65, suggesting that a conventional PKC is involved. Furthermore, transfection of a dominant-negative form of PKCalpha significantly reduces NT-induced IL-8 promoter activity. These results indicate that the conventional PKCalpha is an important mediator in the proinflammatory signaling pathway elicited by NT at the colonocyte level.
Zhao
Dezheng
D
Gastrointestinal Neuropeptide Center, Division of Gastroenterology, Beth Israel Deaconess Medical Center, Dana 601, 330 Brookline Avenue, Boston, MA 02215, USA.
Zhan
Yanai
Y
Zeng
Huiyan
H
Koon
Hon-Wai
HW
Moyer
Mary P
MP
Pothoulakis
Charalabos
C
D000818:Animals; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000378:metabolism*; D007313:Insecta; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009496:Neurotensin / Q000502:physiology*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D051571:Protein Kinase C-alpha; D051996:Transcription Factor RelA
D020672:I-kappa B Proteins; D016209:Interleukin-8; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D051996:Transcription Factor RelA; D000072000:NF-KappaB Inhibitor alpha; D009496:Neurotensin; C496628:PRKCA protein, human; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha