CARP2 deficiency does not alter induction of NF-κB by TNFα

Abstract

SummaryTNFα can activate pathways leading to caspase-8-mediated apoptosis, as well as inflammatory pathways signaled by transcription factors. The adaptor protein RIP1 is a critical component for TNF receptor 1 (TNFR1)-mediated activation of NF-κB, because deletion of the gene encoding RIP1 in mice prevents induction of NF-κB by TNFα and causes severe runting with early postnatal lethality [1]. Recently, it has been proposed that caspase 8 and 10 associated RING protein-2 (CARP2, also named RIFIFYLIN/SAKURA) binds to the TNFR1 complex, leading to ubiquitylation and proteasome-mediated degradation of RIP1, thereby limiting the level of NF-κB activated by TNFα [2]. However, our experiments in mice lacking the Rififylin/Carp2 gene question this conclusion, because levels of RIP1 and induction of NF-κB by TNFα are normal in the absence of CARP2