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J Biol Chem. 2017 Oct 20;292(42):17514-17524. doi: 10.1074/jbc.M117.799353. Epub 2017 Sep 6.

Thioredoxin-1 actively maintains the pseudokinase MLKL in a reduced state to suppress disulfide bond-dependent MLKL polymer formation and necroptosis.

Author information

1
From the Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390.
2
School of Pharmacy, Jiangxi University of Traditional Chinese Medicine, Nanchang, Jiangxi 330006, China, and.
3
Proteomics Facility, National Institute of Biological Sciences, Beijing 102206, China.
4
From the Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, Zhigao.wang@utsouthwestern.edu.

Abstract

Necroptosis is an immunogenic cell death program that is associated with a host of human diseases, including inflammation, infections, and cancer. Receptor-interacting protein kinase 3 (RIPK3) and its substrate mixed lineage kinase domain-like protein (MLKL) are required for necroptosis activation. Specifically, RIPK3-dependent MLKL phosphorylation promotes the assembly of disulfide bond-dependent MLKL polymers that drive the execution of necroptosis. However, how MLKL disulfide bond formation is regulated is not clear. In this study we discovered that the MLKL-modifying compound necrosulfonamide cross-links cysteine 86 of human MLKL to cysteine 32 of the thiol oxidoreductase thioredoxin-1 (Trx1). Recombinant Trx1 preferentially binds to monomeric MLKL and blocks MLKL disulfide bond formation and polymerization in vitro Inhibition of MLKL polymer formation requires the reducing activity of Trx1. Importantly, shRNA-mediated knockdown of Trx1 promotes MLKL polymerization and sensitizes cells to necroptosis. Furthermore, pharmacological inhibition of Trx1 with compound PX-12 induces necroptosis in multiple cancer cell lines. Altogether, these findings demonstrate that Trx1 is a critical regulator of necroptosis that suppresses cell death by maintaining MLKL in a reduced inactive state. Our results further suggest new directions for targeted cancer therapy in which thioredoxin inhibitors like PX-12 could potentially be used to specifically target cancers expressing high levels of MLKL or MLKL short isoforms.

KEYWORDS:

necrosis (necrotic death); serine/threonine protein kinase; thioredoxin; tumor necrosis factor (TNF); tumor therapy

PMID:
28878015
PMCID:
PMC5655526
DOI:
10.1074/jbc.M117.799353
[Indexed for MEDLINE]
Free PMC Article

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