Palmitoylation of TNF alpha is involved in the regulation of TNF receptor 1 signalling

Abstract

The pleiotropic pro-inflammatory cytokine tumour necrosis factor alpha (TNF) is synthesised as a transmembrane protein that is subject to palmitoylation. In this study, the roles of this acylation on TNF-mediated biological effects were investigated. We found that the lipid raft partitioning of TNF is regulated by its palmitoylation. Furthermore, we demonstrated that this palmitoylation process interferes with the cleavage/degradation of TNF intracellular fragments but is not involved in the regulation of its ectodomain shedding. Moreover, we found that the palmitoylation of TNF hinders the binding of soluble TNF to TNFR1 and regulates the integration/retention of TNFR1 into lipid rafts. Finally, we demonstrate that the transmembrane forms of wild-type and palmitoylation-defective TNF interact differently with TNFR1 and regulate NFκB activity, Erk1/2 phosphorylation and interleukin-6 synthesis differently, strongly suggesting that palmitoylation of TNF is involved in the regulation of TNFR1 signalling. An evidence for the physiological intervention of this regulation is provided by the fact that, in macrophages, the binding of endogenous soluble TNF to TNFR1 is enhanced by inhibition of palmitoylation. Therefore, our data introduce the new concept that palmitoylation of TNF is one of the means by which TNF-producing cells regulate their sensitivity to soluble TNF.

Identification of SH3 Domain Proteins Interacting with the Cytoplasmic Tail of the A Disintegrin and Metalloprotease 10 (ADAM10)

“…For example, palmitoylation of the Fas ligand (FasL, CD95L) is essential for its killing capacity and also for its proteolytic processing by ADAM10 and SPPL2a [46]. In contrast, palmitoylation of TNF-α is involved in lipid raft positioning of the cytokine and seems to interfere with the cleavage/degradation of TNF intracellular fragments, but is not involved in the regulation of its ectodomain shedding by ADAM17 [47]. Also, the shedding of the NKG2D ligands MICA/B (MHC-class-I-related chain A/B) was shown to be regulated by their localization in cholesterol-enriched domains, while inhibition of palmitoylation by 2-bromopalmitate led to reduced shedding [48], [49].…”

Multifactorial Regulation of G Protein-Coupled Receptor Endocytosis

“…By contrast, palmitoylation is not required for normal signaling by some GPCRs, such as α 2A AR (Kennedy and Limbird, 1993; Eason et al ., 1994) and thyrotropin receptor (Kosugi and Mori, 1996). In the case of tumor necrosis factor (TNF)α receptor, a member of the cytokinereceptor family, the affinity of the receptor for TNF decreases when the TNF ligand is palmitoylated (Poggi et al ., 2013), suggesting that palmitoylation of ligand rather than receptor could regulate signaling. Palmitoylation-mediated redistribution of GPCRs between lipid raft and non-raft microdomains on the plasma membrane indirectly implicates palmitoylation in biased signaling (Zheng et al ., 2008, 2013).…”

The Deleterious Effects of Oxidative and Nitrosative Stress on Palmitoylation, Membrane Lipid Rafts and Lipid-Based Cellular Signalling: New Drug Targets in Neuroimmune Disorders

“…The essential role of S-palmitoylation and lipid raft activity • B cell CD20 and CD23 function[26] • TLR-4, TLR-2 and NOD-like receptor function [30-32] • TNF receptor signaling[293] …”