Apoptotic Caspases Suppress Type I Interferon Production via the Cleavage of cGAS, MAVS, and IRF3.

Viral infection triggers host defenses through pattern-recognition receptor-mediated cytokine production, inflammasome activation, and apoptosis of the infected cells. Inflammasome-activated caspases are known to cleave cyclic GMP-AMP synthase (cGAS). Here, we found that apoptotic caspases are critically involved in regulating both DNA and RNA virus-triggered host defenses, in which activated caspase-3 cleaved cGAS, MAVS, and IRF3 to prevent cytokine overproduction. Caspase-3 was exclusively required in human cells, whereas caspase-7 was involved only in murine cells to inactivate cGAS, reflecting distinct regulatory mechanisms in different species. Caspase-mediated cGAS cleavage was enhanced in the presence of dsDNA. Alternative MAVS cleavage sites were used to ensure the inactivation of this critical protein. Elevated type I IFNs were detected in caspase-3-deficient cells without any infection. Casp3-/- mice consistently showed increased resistance to viral infection and experimental autoimmune encephalomyelitis. Our results demonstrate that apoptotic caspases control innate immunity and maintain immune homeostasis against viral infection. Copyright © 2019 Elsevier Inc. All rights reserved.

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Xiaohan Ning, Yutao Wang, Miao Jing, Mengyin Sha, Mengze Lv, Pengfei Gao, Rui Zhang, Xiaojun Huang, Ji-Ming Feng, Zhengfan Jiang. Apoptotic Caspases Suppress Type I Interferon Production via the Cleavage of cGAS, MAVS, and IRF3. Molecular cell. 2019 Apr 04;74(1):19-31.e7

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PMID: 30878284

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