AKT-mediated phosphorylation of ZDHHC5 promotes NOD1 palmitoylation and innate immune signaling

Nucleotide-binding oligomerization domain 1 (NOD1) is an intracellular pattern recognition receptor that detects bacterial peptidoglycan and initiates innate immune responses through membrane-associated signaling complexes. NOD1 activation depends on ZDHHC5-mediated palmitoylation, which promotes its membrane recruitment. However, whether growth factors and insulin modulate this NOD1 activation remains poorly defined.

We investigated the effects of growth factors and insulin on NOD1 signaling using biochemical and cell-based approaches. Protein phosphorylation and interactions were analyzed by immunoblotting, co-immunoprecipitation, and mutagenesis assays. NOD1 palmitoylation, membrane localization, and downstream signaling activities were evaluated following modulation of AKT signaling and ZDHHC5 phosphorylation.

We found that growth factors and insulin positively regulate NOD1 activation through an AKT-ZDHHC5-NOD1 signaling axis. Mechanistically, AKT directly phosphorylated the palmitoyltransferase ZDHHC5 at Ser345 and Ser380, promoting its retention at the plasma membrane and enhancing its enzymatic activity toward NOD1. AKT-dependent phosphorylation increased NOD1 palmitoylation and membrane recruitment, thereby facilitating activation of downstream innate immune signaling pathways.

These findings identify a previously unrecognized mechanism linking growth factor- and insulin-mediated AKT activation to innate immune signaling. AKT-dependent phosphorylation of ZDHHC5 promotes NOD1 palmitoylation and activation, revealing a positive regulatory axis that integrates metabolic cues with innate immune responses. The AKT-ZDHHC5 pathway may therefore represent a potential target for modulating NOD1- driven inflammatory diseases.