Straight A's: protein acylation in the S-activation and autophagic degradation of NOD-like receptors.

Abstract

Over the past decade, S-acylation has emerged as a crucial regulator of several innate immune signaling pathways, with new insights continually being gained. S-acylation, a reversible post-translational modification, involves the attachment of fatty acyl chains to cysteine residues, influencing protein localization, function, and stability. In this mini-review, we examine the accumulating evidence of the role of S-acylation in regulating nucleotide oligomerization domain (NOD)-like receptors. NOD-like receptor subfamily P3 (NLRP3), a key player in inflammasome formation, undergoes S-acylation at specific cysteine residues, which are essential for its localization to the trans-Golgi network and other organelles. Various zinc finger Asp-His-His-Cys motif-containing (zDHHC) enzymes mediate this modification, with zDHHC5 being particularly important for activation and the ability of NLRP3 to interact with never in mitosis gene A (NIMA)-related protein kinase 7 (NEK7), promoting inflammasome assembly, caspase-1 activation, and pyroptosis. Alternatively, S-acylation by zDHHC12 targets NLRP3 for chaperone-mediated autophagy, preventing excessive inflammation. NOD2, another NLR, requires S-acylation for membrane localization and effective signaling via the NF-κB and mitogen-activated protein kinase pathways in response to peptidoglycan components. Dysregulation of S-acylation in NOD2 is associated with Crohn's Disease (hypo-acylated) and Blau syndrome/early-onset sarcoidosis (hyper-acylated). Soluble NOD2 lacking S-acylation is ubiquitinated and eliminated by the autophagic pathway. This review highlights the significance of understanding the S-acylation cycle and its regulatory mechanisms in developing potential therapeutic interventions for related inflammatory diseases. We also discuss unresolved questions regarding the S-acylation of NOD2 and NLRP3, as well as the regulation of S-acylation in general.