CARP-2 is an endosome-associated ubiquitin ligase for RIP and regulates TNF-induced NF-kappaB activation.

BACKGROUND: The proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) elicits cellular responses by signaling through a receptor complex that includes the essential adaptor molecule RIP. One important consequence of signaling is activation of the transcription factor NF-kappaB, and failure to downregulate TNF-induced NF-kappaB transcriptional activity results in chronic inflammation and death. ...
Internalization of the receptor complex plays an important regulatory role in TNF signaling. RESULTS: We report that CARP-2, a RING domain-containing ubiquitin protein ligase (E3), is a negative regulator of TNF-induced NF-kappaB activation. By virtue of its phospholipid-binding FYVE domain, CARP-2 localized to endocytic vesicles, where it interacted with internalized TNF-receptor complex, resulting in RIP ubiquitination and degradation. Knockdown of CARP-2 stabilized TNFR1-associated polyubiquitinated RIP levels after TNF simulation and enhanced activation of NF-kappaB. CONCLUSIONS: CARP-2 acts at the level of endocytic vesicles to limit the intensity of TNF-induced NF-kappaB activation by the regulated elimination of a necessary signaling component within the receptor complex.
Mesh Terms:
Cell Line, Endocytosis, Humans, NF-kappa B, Receptor-Interacting Protein Serine-Threonine Kinases, Transport Vesicles, Tumor Necrosis Factor-alpha, Ubiquitin-Protein Ligases
Curr. Biol.
Date: May. 06, 2008
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