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J Clin Invest. 2004 Mar;113(5):746-55.

IkappaBalpha and IkappaBbeta possess injury context-specific functions that uniquely influence hepatic NF-kappaB induction and inflammation.

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1
Molecular Biology Program, College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA.

Abstract

IkappaB proteins play an important role in regulating NF-kappaB induction following a diverse range of environmental injuries. Studies evaluating IkappaBbeta knock-in mice (AKBI), in which the IkappaBalpha gene is replaced by the IkappaBbeta cDNA, have uncovered divergent properties of IkappaBalpha and IkappaBbeta that influence their ability to activate hepatic NF-kappaB and subsequent downstream proinflammatory processes in a stimulus-specific manner. While AKBI mice demonstrated identical levels of hepatic NF-kappaB activation in response to endotoxin, a significantly reduced level of hepatic NF-kappaB activation was observed in AKBI mice after liver ischemia/reperfusion (I/R) injury. This reduced level of NF-kappaB activation in AKBI mice after liver I/R also correlated with decreased induction of serum TNF-alpha, reduced hepatic inflammation, and increased survival. In contrast, no differences in any of these indicators were observed between AKBI mice and WT littermates after a lethal injection of LPS. Molecular studies suggest that the specificity of IkappaBalpha, but not IkappaBbeta, to properly regulate NF-kappaB induction during the acute phase of I/R injury is due to injury context-specific activation of c-Src and subsequent tyrosine phosphorylation of IkappaBalpha on Tyr42. These results demonstrate that IkappaBalpha and IkappaBbeta play unique injury context-specific roles in activating NF-kappaB-mediated proinflammatory responses and suggest that strategies aimed at inhibiting IkappaBalpha gene expression may be of potential therapeutic benefit in hepatic I/R injury.

PMID:
14991073
PMCID:
PMC351311
DOI:
10.1172/JCI17337
[Indexed for MEDLINE]
Free PMC Article
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