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 TNF). 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.
Bibliographical noteFunding Information:
We thank S. Murata for the Chip−/− mice and V. M. Dixit for the Ripk3−/− mice. We thank the Cancer Metabolism Interest Group (cMIG) led by NCC Korea for discussion and advice. This research was supported by a grant from the National R&D Program for Cancer Control, Ministry of Health & Welfare, Republic of Korea (NCC-1420300) (to J.Song) and by a grant from the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2012R1A6A3A04040105) (to E.-W.L.) and by the Ministry of Science, ICT and Future Planning (NRF-2015R1A3A2066581) (to J.Song). Research in the Vandenabeele group is supported by Flemish grants (Research Foundation Flanders: FWO G.0875.11, FWO G.0973.11, FWO G.0A45.12N, FWO G.0787.13N, FWO G0E04.16N), a Methusalem grant (BOF16/MET_V/007), Ghent University grants (MRP, GROUP-ID consortium), a grant from the Foundation against Cancer (F94), and grants from VIB. Additionally, this research was partly supported by the BK21 Plus project of the National Research Foundation of Korea Grant (to J.Seo, M.J., H.-K.L., D.S., J.-H.K. and S.Y.H.) and by the grants for KMPC (Korea Mouse Phenotype Center) (to J.K.S.) from National Research Foundation of Korea (NRF), and C.L. acknowledges institutional support by KIST.
© 2016 Macmillan Publishers Limited.
All Science Journal Classification (ASJC) codes
- Cell Biology