The integrated stress response kinase GCN2 prevents ZAKα-Dependent inflammatory hyperactivation in macrophages.

Abstract

Macrophages orchestrate inflammation through rapid and extensive proteome remodeling, yet the translational programs governing macrophage activation remain poorly defined. Here, we show that classically activated macrophages (LPS+IFNγ-treated) and alternatively activated macrophages (IL-4-treated) engage fundamentally distinct translational trajectories. Whereas alternatively activated macrophages sustain elevated protein synthesis, classically activated macrophages undergo a rapid but transient increase in translation that is subsequently restrained by the integrated stress response (ISR) kinase General Control Nonderepressible 2 (GCN2). Using puromycin incorporation, polysome profiling, and quantitative proteomics, we demonstrate that GCN2-mediated phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) limits global translation and constrains the pro-inflammatory response. Genetic loss of GCN2 results in excessive translation and hyperinflammation driven by the ribosome-associated stress sensor ZAKα (MAP3K20). Importantly, pharmacological inhibition of ZAKα in GCN2-deficient macrophages selectively normalizes tumor necrosis factor α (TNFα) secretion, establishing a functional regulatory axis in which GCN2 suppresses ZAKα-dependent inflammatory signaling. Together, these findings redefine translational control as a central checkpoint in macrophage activation, revealing how GCN2 mitigates ribosomal stress to prevent inflammatory hyperactivation, with potential therapeutic implications for TNFα-driven inflammatory diseases.