Description

Inflammation is beneficial when it is part of the innate immune response, but harmful when it occurs in an unregulated, chronic manner. We now report that IkappaB-beta, a member of the classical IkappaB family, serves a dual role of both inhibiting and facilitating the inflammatory response. IkappaB-beta degradation releases NF-kappaB dimers which upregulate proinflammatory target genes such as TNF-alpha. Suprisingly absence of IkappaB-beta results in a dramatic reduction of TNF-alpha in response to LPS even though the activation of NF-kappaB is normal. The inhibition of TNF-alpha mRNA expression can be correlated to the absence of nuclear, hypophosphorylated-IkappaB-beta bound to p65:cRel heterodimers at a specific kappaB site on the TNF-alpha promoter. Therefore IkappaB-beta acts through p65:cRel dimers to maintain prolonged expression of TNF-alpha. As a result, IkappaB-beta knockout mice are resistant to LPS induced septic shock and collagen-induced arthritis, and therefore blocking IkappaB-beta might be a promising new strategy for selectively inhibiting the chronic phase of TNF-alpha producting during the inflammatory response.

Publication Title

IkappaBbeta acts to inhibit and activate gene expression during the inflammatory response.

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