Enhancer of Zeste homolog 2-mediated histone H3 lysine 27 trimethylation silences LIM domain-containing protein 1 and activates hippo signaling in Mycoplasma pathogenesis

Mycoplasma gallisepticum (MG), a leading cause of chronic respiratory disease in poultry, provokes sustained inflammation and immune dysregulation; however, its molecular pathogenesis remains incompletely defined. Here, we identify EZH2-mediated trimethylation of histone H3 lysine 27 (H3K27me3) as a critical host epigenetic modification upregulated during MG Infection, both in vitro and in vivo. This repressive histone MARK facilitates MG pathogenesis by promoting Bacterial adhesion, elevating pro-inflammatory cytokines, and inducing macrophage Apoptosis. Pharmacological blockade of EZH2 with GSK343 significantly reduced MG burden, highlighting the pathogenic role of H3K27me3. Integrative transcriptomic and CUT&Tag profiling revealed LIMD1 as a direct epigenetic target silenced by H3K27me3. Functional assays demonstrated that LIMD1 overexpression restores cytokine homeostasis, limits MG replication, and protects against Apoptosis, while LIMD1 knockdown reverses these effects. Mechanistically, LIMD1 suppresses Hippo pathway activation, preserving nuclear YAP1 and its downstream anti-inflammatory and pro-survival functions. Notably, LIMD1 was required for the protective effects of EZH2 inhibition, and its function was dependent on intact YAP1 signaling. Collectively, our findings uncover a novel EZH2-H3K27me3-LIMD1-Hippo-YAP1 axis that governs host susceptibility to MG Infection. Targeting this epigenetic circuit may offer novel strategies for host-directed therapy against avian mycoplasmosis.

Epigenetic regulation; H3K27me3; Hippo-YAP1 signaling; LIMD1; Mycoplasma gallisepticum.