Rapid activation of NF-kappaB and AP-1 and target gene expression in postischemic rat intestine.
OBJECTIVE
The molecular mechanisms underlying intestinal mucosal damage-repair processes induced by ischemia-reperfusion (IR) remain unknown. We determined nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1) activities and the expression of potential target genes relevant to damage-repair events.


METHODS
Rat jejunal segment was subjected to ischemia for 30 minutes followed by reperfusion for defined times. NF-kappaB and AP-1 activities; mucosal p105, p50, and inhibitor kappaB-alpha (IkappaB-alpha) levels; and c-fos, neurotensin, and ferritin H expression were determined by electrophoretic mobility shift assay and Western and Northern analyses, respectively.


RESULTS
NF-kappaB and AP-1 activities were significantly elevated from 1 to 12 hours after reperfusion. The activated NF-kappaB in the nuclear extract consisted of solely p50 homodimers. Activation of p50 was associated with a decrease of p105, generation of p50, and increased phosphorylation and degradation of IkappaB-alpha. The activated AP-1 contained c-fos but not c-jun, fosB, and Fra-1. Reperfusion induced a transient elevation of c-fos, prolonged increase of neurotensin, and early reduction followed by recovery of ferritin H messenger RNA.


CONCLUSIONS
The intestine shows organ-specific responses to IR, characterized by prolonged NF-kappaB and AP-1 activation involving NF-kappaB p50 dimers and excluding AP-1 c-jun protein. Degradation of the IkappaB-gamma component of p105 and partial reduction IkappaB-alpha selectively activate p50/p50 dimers. Temporal patterns of target gene expression reflect functional relevance to mucosal damage-repair processes after IR.
Yeh
K Y
KY
Department of Medicine, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130, USA.
Yeh
M
M
Glass
J
J
Granger
D N
DN
D000818:Animals; D004247:DNA / Q000378:metabolism; D005293:Ferritins / Q000235:genetics; D005786:Gene Expression Regulation; D007413:Intestinal Mucosa / Q000378:metabolism; D007511:Ischemia / Q000235:genetics* / Q000378:metabolism; D007583:Jejunum / Q000098:blood supply*; D016328:NF-kappa B / Q000235:genetics* / Q000378:metabolism; D009496:Neurotensin / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000235:genetics* / Q000378:metabolism; D014018:Tissue Distribution; D018808:Transcription Factor AP-1 / Q000235:genetics* / Q000378:metabolism
D016328:NF-kappa B; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D009496:Neurotensin; D004247:DNA; D005293:Ferritins