Palmitoylation is required for TNF-R1 signaling

BACKGROUND: Binding of tumor necrosis factor (TNF) to TNF-receptor 1 (TNF-R1) can induce either cell survival or cell death. The selection between these diametrically opposed effects depends on the subcellular location of TNF-R1: plasma membrane retention leads to survival, while endocytosis leads to cell death. How the respective TNF-R1 associated signaling complexes are recruited to the distinct subcellular location is not known. Here, we identify palmitoylation of TNF-R1 as a molecular mechanism to achieve signal diversification. METHODS: Human monocytic U937 cells were analyzed. Palmitoylated proteins were enriched by acyl resin assisted capture (AcylRAC) and analyzed by western blot and mass spectrometry. Palmitoylation of TNF-R1 was validated by metabolic labeling. TNF induced depalmitoylation and involvement of APT2 was analyzed by enzyme activity assays, pharmacological inhibition and shRNA mediated knock-down. TNF-R1 palmitoylation site analysis was done by mutated TNF-R1 expression in TNF-R1 knock-out cells. Apoptosis (nuclear DNA fragmentation, caspase 3 assays), NF-κB activation and TNF-R1 internalization were used as biological readouts. RESULTS: We identify dynamic S-palmitoylation as a new mechanism that controls selective TNF signaling. TNF-R1 itself is constitutively palmitoylated and depalmitoylated upon ligand binding. We identified the palmitoyl thioesterase APT2 to be involved in TNF-R1 depalmitoylation and TNF induced NF-κB activation. Mutation of the putative palmitoylation site C248 interferes with TNF-R1 localization to the plasma membrane and thus, proper signal transduction. CONCLUSIONS: Our results introduce palmitoylation as a new layer of dynamic regulation of TNF-R1 induced signal transduction at a very early step of the TNF induced signaling cascade. Understanding the underlying mechanism may allow novel therapeutic options for disease treatment in future. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12964-019-0405-8) contains supplementary material, which is available to authorized users.