Apomorphine is a novel necroptosis inhibitor targeting mixed lineage kinase domain-like protein oligomerization

Abstract

Necroptosis, a form of programmed cell death, has emerged as a promising therapeutic target. Although several RIPK1 inhibitors have demonstrated favorable safety profiles in clinical trials, clinical translation of necroptosis-targeted therapies remains limited by modest efficacy, limited specificity, and species-specific activity of compounds such as necrosulfonamide (NSA). To resolve these challenges, this study identified a potential necroptosis inhibitor from a clinical drug library. Apomorphine (APO), a non-addictive morphine derivative used to treat Parkinson's disease, was found to inhibit necroptosis by sterically blocking key residues involved in mixed lineage kinase domain-like protein (MLKL) activation and oligomerization, as confirmed by nuclear magnetic resonance analysis. APO is redox sensitive and prone to auto-oxidation. The oxidized form of APO (Ox-APO) showed stronger binding to MLKL than the reduced form of APO (Re-APO), as demonstrated by surface plasmon resonance analysis. Ox-APO significantly ameliorated tissue damage in two murine necroptosis models: dextran sulfate sodium (DSS)-induced colitis and acetaminophen (APAP)-induced liver injury. Collectively, these data highlight the therapeutic potential of APO as a necroptosis-specific inhibitor in necroptosis-related diseases in both humans and mice.