Proteasome inhibition blocks necroptosis by attenuating death complex aggregation

• Type of Material: Article
• Authors: Mohammed K Ali, Emory University; Edward S Mocarski, Emory University
• Language: English
• Date: 2018-03-01
• Publisher: Nature Publishing Group: Open Access Journals - Option C
• Publication Version: Final Published Version
• Copyright Statement: © The Author(s) 2018.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1038/s41419-018-0371-x
• Title of Journal or Parent Work: Cell Death and Disease
• ISSN: 2041-4889
• Volume: 9
• Issue: 3
• Start Page: 346
• End Page: 346
• Grant/Funding Information: This work by supported by an Emory-Onyx (Amgen) Alliance Fund Award and PHS grant AI118853.
• Keywords: ACTIVATION; DOMAIN-LIKE PROTEIN; MULTIPLE-MYELOMA; Life Sciences & Biomedicine; NF-KAPPA-B; TNF-ALPHA; CELL-DEATH; PROGRAMMED NECROSIS; INFLAMMATION; MIXED LINEAGE KINASE; Cell Biology; Science & Technology; T-CELLS
• Research Categories: Health Sciences, Medicine and Surgery; Health Sciences, Immunology; Biology, Microbiology

Abstract

Proteasome inhibitors have achieved clinical success because they trigger intrinsic and extrinsic cell death to eliminate susceptible human cancers. The ubiquitin-proteasome protein degradation system regulates signaling pathways by controlling levels of components such as cellular inhibitor of apoptosis (cIAP)1 and cIAP2 in TNF-mediated cell death. Here, we sought to evaluate the contribution of necroptosis to the cell death pattern induced by the specific proteasome inhibitor Carfilzomib (Cf). Proteasome inhibitor-sensitive multiple myeloma cell lines die in response to Cf by apoptosis in combination with serine protease-dependent death, without any contribution of RIPK3-dependent necroptosis. Proteasome inhibition leads to the induction of apoptotic markers such as activated caspase-3 rather than necroptotic markers such as phosphorylated-MLKL in all cell lines tested. In HT-29 cells, Cf attenuates the late RIPK1 interaction with TNFR1 during TNF-induced necroptosis without altering the sensitivity of cIAP antagonists. Cf treatment results in decreased translocation of death signaling components RIPK1, FADD, caspase-8, cFLIP, and RIPK3 to detergent insoluble fractions. Our results show that proteasome inhibition with Cf impairs necroptosis and favors apoptosis even in cells with intact necroptotic machinery. Following the induction of TNFR1-mediated necroptosis, proteasome activity stabilizes effective aggregation and activation of ripoptosome/necrosome complexes.