Jinho Seo1,6, Eun-Woo Lee1,6, Hyerim Sung2, Daehyeon Seong1, Yves Dondelinger3,4, Jihye Shin1,5, Manhyung Jeong1, Hae-Kyung Lee1, Jung-Hoon Kim1, Su Yeon Han1, Cheolju Lee5, Je Kyung Seong2, Peter Vandenabeele3,4 and Jaewhan Song1,7
1Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea. 2Laboratory of Developmental Biology and Genetics, College of Veterinary Medicine, BK21Plus Program for Creative Veterinary Science Research, Interdisciplinary Program for Bioinformatics, BIO-MAX institute, Korea Mouse Phenotyping Center, Seoul National University, Seoul 151-742, South Korea. 3Department of Biomedical Molecular Biology, Ghent University, Technologiepark 927, 9052 Zwijnaarde-Ghent, Belgium. 4Inflammation Research Center, VIB, Technologiepark 927, 9052 Zwijnaarde-Ghent, Belgium. 5BRI, Korea Institute of Science and Technology, Seoul 136-791, Korea. 6These authors contributed equally to this work.
7Correspondence to : Jaewhan Song
Receptor-interacting protein kinase 3 (RIPK3) functions as a key regulator of necroptosis. Here, we report that the RIPK3 expression level is negatively regulated by CHIP (carboxyl terminus of Hsp70-interacting protein; also known as STUB1) E3 ligase-mediated ubiquitylation. Chip-/- mouse embryonic fibroblasts and CHIP-depleted L929 and HT-29 cells exhibited higher levels of RIPK3 expression, resulting in increased sensitivity to necroptosis induced by TNF (also known as TNFα). These phenomena are due to the CHIP-mediated ubiquitylation of RIPK3, which leads to its lysosomal degradation. Interestingly, RIPK1 expression is also negatively regulated by CHIP-mediated ubiquitylation, validating the major role of CHIP in necrosome formation and sensitivity to TNF-mediated necroptosis. Chip-/- mice (C57BL/6) exhibit inflammation in the thymus and massive cell death and disintegration in the small intestinal tract, and die within a few weeks after birth. These phenotypes are rescued by crossing with Ripk3-/- mice. These results imply that CHIP is a bona fide negative regulator of the RIPK1-RIPK3 necrosome formation leading to desensitization of TNF-mediated necroptosis.