NF-κB Protects Cells from Gamma Interferon-Induced RIP1-Dependent Necroptosis

Abstract

Interferons (IFNs) are cytokines with well-described immunomodulatory and antiviral properties, but less is known about the mechanisms by which they promote cell survival or cell death. Here, we show that IFN-γ induces RIP1 kinase-dependent necroptosis in mammalian cells deficient in NF-κB signaling. Induction of necroptosis by IFN-γ was found to depend on Jak1 and partially on STAT1. We also demonstrate that IFN-γ activates IκB kinase β (IKKβ)-dependent NF-κB to regulate a transcriptional program that protects cells from necroptosis. IFN-γ induced progressive accumulation of reactive oxygen species (ROS) and eventual loss of mitochondrial membrane potential in cells lacking the NF-κB subunit RelA. Whole-genome microarray analyses identified sod2, encoding the antioxidant enzyme manganese superoxide dismutase (MnSOD), as a RelA target and potential antinecroptotic gene. Overexpression of MnSOD inhibited IFN-γ-mediated ROS accumulation and partially rescued RelA-deficient cells from necroptosis, while RNA interference (RNAi)-mediated silencing of sod2 expression increased susceptibility to IFN-γ-induced cell death. Together, these studies demonstrate that NF-κB protects cells from IFN-γ-mediated necroptosis by transcriptionally activating a survival response that quenches ROS to preserve mitochondrial integrity.

ACKNOWLEDGMENTS

We thank Yutaro Kumagai, Taro Kawai, and Shizuo Akira for myd88^−/−/trif^−/− cells. We also thank Yuesheng Li for generating microarray data. We are grateful to Glenn Rall and Christoph Seeger for valuable comments.

This work was supported by an ACS Research Scholar Grant (RSG-09-195-01-MPC) to S.B. and National Institutes of Health grant (RO1-HL086699) to M.M. Additional funds were provided by the Fox Chase Cancer Center via institutional support of the Kidney Cancer Keystone Program.

R.J.T. and S.H.B. performed most of the experiments and participated in writing the manuscript. K.I. and K.M. carried out all experiments relating to mitochondrial ROS and Δψm measurements. S.N. performed chromatin immunoprecipitation experiments. M.J.S. analyzed microarray data. A.A.B. generated rela^−/− and ikkβ^−/− MEFs and littermate control MEFs and edited the manuscript. M.M. oversaw work performed by K.I. and K.M. and edited the manuscript. S.B. designed the experiments, interpreted data, and wrote the manuscript.

We declare that we have no conflicts of interest.