Protein Acylation by Saturated Very Long Chain Fatty Acids and Endocytosis Are Involved in Necroptosis

Necroptosis is a form of regulated cell death that is characterized by membrane permeabilization. This permeabilization is responsible for the inflammatory properties of necroptosis and is critical for disease states involving this process. We previously showed that very long chain fatty acids (VLCFAs) are functionally involved in necroptosis, potentially through protein fatty acylation. Here, we define the scope of protein acylation by saturated VLCFAs during necroptosis. We show that mixed lineage kinase like protein (MLKL) and phosphoMLKL, key proteins for membrane permeabilization, are exclusively acylated during necroptosis. Reducing the levels of VLCFAs decreases their membrane recruitment, suggesting that acylation by VLCFAs contributes to their membrane localization. Acylation of phosphoMLKL occurs downstream of phosphorylation and oligomerization and appears to be, in part, mediated by ZDHHC5 (a palmitoyl transferase). We also show that disruption of the clathrin-mediated endocytosis increases cell viability during necroptosis, likely by removing phosphoMLKL from the plasma membrane.