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Autophagosomal IkappaB alpha degradation plays a role in the long term control of tumor necrosis factor-alpha-induced nuclear factor-kappaB (NF-kappaB) activity.

ABSTRACT: Transcription factor NF-?B is persistently activated in many chronic inflammatory diseases and cancers. The short term regulation of NF-?B is well understood, but little is known about the mechanisms of its long term activation. We studied the effect of a single application of TNF-? on NF-?B activity for up to 48 h in intestinal epithelial cells. Results show that NF-?B remained persistently activated up to 48 h after TNF-? and that the long term activation of NF-?B was accompanied by a biphasic degradation of I?B?. The first phase of I?B? degradation was proteasome-dependent, but the second was not. Further investigation showed that TNF-? stimulated formation of autophagosomes in intestinal epithelial cells and that I?B? co-localized with autophagosomal vesicles. Pharmacological or genetic blockade of autophagosome formation or the inhibition of lysosomal proteases decreased TNF-?-induced degradation of I?B? and lowered NF-?B target gene expression. Together, these findings indicate a role of autophagy in the control of long term NF-?B activity. Because abnormalities in autophagy have been linked to ineffective innate immunity, we propose that alterations in NF-?B may mediate this effect.

SUBMITTER: Colleran A

PROVIDER: S-EPMC3123056 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature

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Autophagosomal IkappaB alpha degradation plays a role in the long term control of tumor necrosis factor-alpha-induced nuclear factor-kappaB (NF-kappaB) activity.

Colleran Amy A Ryan Aideen A O'Gorman Angela A Mureau Coralie C Liptrot Catherine C Dockery Peter P Fearnhead Howard H Egan Laurence J LJ

The Journal of biological chemistry 20110331 26

Transcription factor NF-κB is persistently activated in many chronic inflammatory diseases and cancers. The short term regulation of NF-κB is well understood, but little is known about the mechanisms of its long term activation. We studied the effect of a single application of TNF-α on NF-κB activity for up to 48 h in intestinal epithelial cells. Results show that NF-κB remained persistently activated up to 48 h after TNF-α and that the long term activation of NF-κB was accompanied by a biphasic ...[more]

PMID: 21454695

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Project description:Nuclear factor-kappaB (NF-kappaB) is a ubiquitous transcription factor that regulates various kinds of genes including inflammatory molecules, macrophage infiltration factors, cell adhesion molecules, and so forth, in various disease processes including cardiac hypertrophy and heart failure. Previously, we have demonstrated that activation of NF-kappaB was required in myotrophin-induced cardiac hypertrophy, in spontaneously hypertensive rats, and in dilated cardiomyopathy human hearts. Moreover, our recent study using the myotrophin-overexpressed transgenic mouse (Myo-Tg) model showed that short hairpin RNA-mediated knockdown of NF-kappaB significantly attenuated cardiac mass associated with improved cardiac function. Although it has been shown that NF-kappaB is substantially involved in cardiovascular remodeling, it is not clear whether the continuous blockade of NF-kappaB is effective in cardiovascular remodeling. To address this question, we took a genetic approach using IkappaB alpha triple mutant mice (3M) bred with Myo-Tg mice (a progressive hypertrophy/heart failure model). The double transgenic mice (Myo-3M) displayed an attenuated cardiac hypertrophy (9.8+/-0.62 versus 5.4+/-0.34, p<0.001) and improved cardiac function associated with significant inhibition of the NF-kappaB signaling cascade, hypertrophy marker gene expression, and inflammatory and macrophage gene expression at 24 weeks of age compared to Myo-Tg mice. NF-kappaB-targeted gene array profiling displayed several important genes that were significantly downregulated in Myo-3M mice compared to Myo-Tg mice. Furthermore, Myo-3M did not show any changes of apoptotic gene expression, indicating that significant inhibition of NF-kappaB activation reduces further proinflammatory reactions without affecting susceptibility to apoptosis. Therefore, development of therapeutic strategies targeting NF-kappaB may provide an effective approach to prevent adverse cardiac pathophysiological consequences.

Dataset Information

Autophagosomal IkappaB alpha degradation plays a role in the long term control of tumor necrosis factor-alpha-induced nuclear factor-kappaB (NF-kappaB) activity.

Publications

Autophagosomal IkappaB alpha degradation plays a role in the long term control of tumor necrosis factor-alpha-induced nuclear factor-kappaB (NF-kappaB) activity.

Similar Datasets

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