IκB-Mediated Inhibition of Virus-Induced Beta Interferon Transcription

Abstract

We have examined the consequences of overexpression of the IκBα and IκBβ inhibitory proteins on the regulation of NF-κB-dependent beta interferon (IFN-β) gene transcription in human cells after Sendai virus infection. In transient coexpression studies or in cell lines engineered to express different forms of IκB under tetracycline-inducible control, the IFN-β promoter (−281 to +19) linked to the chloramphenicol acetyltransferase reporter gene was differentially inhibited in response to virus infection. IκBα exhibited a strong inhibitory effect on virus-induced IFN-β expression, whereas IκBβ exerted an inhibitory effect only at a high concentration. Despite activation of the IκB kinase complex by Sendai virus infection, overexpression of the double-point-mutated (S32A/S36A) dominant repressors of IκBα (TD-IκBα) completely blocked IFN-β gene activation by Sendai virus. Endogenous IFN-β RNA production was also inhibited in Tet-inducible TD-IκBα-expressing cells. Inhibition of IFN-β expression directly correlated with a reduction in the binding of NF-κB (p50-RelA) complex to PRDII after Sendai virus infection in IκBα-expressing cells, whereas IFN-β expression and NF-κB binding were only slightly reduced in IκBβ-expressing cells. These experiments demonstrate a major role for IκBα in the regulation of NF-κB-induced IFN-β gene activation and a minor role for IκBβ in the activation process.

Interleukin‐4 and interleukin‐10 modulate nuclear factor κB activity and nitric oxide synthase‐2 expression in Theiler's virus‐infected brain astrocytes

“…The degradation and resynthesis of IjBa occurs rapidly and parallels the initial NF-jB activation, whereas the persistent IjBb degradation correlates with a sustained NF-jB activation (Thompson et al 1995). Similarly, in response to Sendai virus infection it was demonstrated a major role for IjBa in the regulation of NF-jB-induced IFN-b expression, and a minor role for IjBb in the activation process (Algarté et al 1999). By contrast, the African swine fever virus encodes a protein with homology to the ankyrin repeats of IjB, which behaves as an inhibitor of NF-jB activity (Revilla et al 1998), likely representing a mechanism to evade the immune response.…”

NF‐κB‐dependent regulation of brain‐derived neurotrophic factor in hippocampal neurons by X‐linked inhibitor of apoptosis protein

“…To control for transfection efficiency, 0.02 μg Renilla luciferase pRL‐TK was used. To inhibit NF‐κB, we used 1 μg of the expression plasmid encoding inhibitor of NF‐κB (I‐κB) (a kind gift from Dr J. Hiscott, McGill University, Canada) (Algarté et al. , 1999).…”

Regulation of Sox9 activity by crosstalk with nuclear factor-κB and retinoic acid receptors

“…Previous studies have shown that multiple repeats of the minimal enhancer are required for optimal output [ 29 ]. For some experiments, chondrocytes were co-transfected with reporter constructs and expression constructs for constitutively active mitogen-activated protein kinase kinase kinase (caMEKK)1 (Clontech, Mountain View, CA, USA), a phosphorylation site-deficient IκB (IκB-2N; pSVK3-IκB-2NΔ4) [ 30 ], or p300. In all experiments, chondrocytes were co-transfected with a 0.002 μg renilla luciferase plasmid (pRL-SV40; Promega), which was used in most cases to control for transfection efficiency.…”