The ubiquitin-modifying enzyme A20 restricts ubiquitination of the kinase RIPK3 and protects cells from necroptosis

• DOI: 10.1038/ni.3172
• Publication Date: 2015-05-04T17:20:04Z
• Authors: Michio Onizawa; Shigeru Oshima; Ulf Schulze-Topphoff; Juan A Oses-Prieto; Timothy Lu; Rita Tavares; Thomas Prodhomme; Bao Duong; Michael I Whang; Rommel Advincula; Alex Agelidis; Julio Barrera; Hao Wu; Alma Burlingame; Barbara A Malynn; Scott S Zamvil; Averil Ma
• Keywords: 0301 basic medicine; 572; Knockout; T-Lymphocytes; Immunology; Apoptosis; Inbred C57BL; Jurkat Cells; Mice; Necrosis; 03 medical and health sciences; Catalytic Domain; Animals; Humans; Ubiquitins; Tumor Necrosis Factor alpha-Induced Protein 3; Mice, Knockout; Intracellular Signaling Peptides and Proteins; Ubiquitination; Biological Sciences; Fibroblasts; 3. Good health; Mice, Inbred C57BL; Cysteine Endopeptidases; Biochemistry and cell biology; Multiprotein Complexes; Receptor-Interacting Protein Serine-Threonine Kinases; Biochemistry and Cell Biology; Protein Binding

A20 is an anti-inflammatory protein linked to multiple human diseases; however, the mechanisms by which A20 prevents inflammatory disease are incompletely defined. We found that A20-deficient T cells and fibroblasts were susceptible to caspase-independent and kinase RIPK3-dependent necroptosis. Global deficiency in RIPK3 significantly restored the survival of A20-deficient mice. A20-deficient cells exhibited exaggerated formation of RIPK1-RIPK3 complexes. RIPK3 underwent physiological ubiquitination at Lys5 (K5), and this ubiquitination event supported the formation of RIPK1-RIPK3 complexes. Both the ubiquitination of RIPK3 and formation of the RIPK1-RIPK3 complex required the catalytic cysteine of A20's deubiquitinating motif. Our studies link A20 and the ubiquitination of RIPK3 to necroptotic cell death and suggest additional mechanisms by which A20 might prevent inflammatory disease.