Dual mechanism of human ATG10S in suppressing MEF2A-Driven pro-inflammatory responses

Cytokine storm, characterized by excessive release of pro-inflammatory cytokines, contributes to the severity and exacerbation of various diseases. Current therapies targeting individual cytokines prove inadequate due to the complex and multifactorial nature of inflammatory cascades. Here, we report human ATG10S, a novel isoform of the autophagy-related protein ATG10, as a potential inhibitor of cytokine storms. Using SARS-CoV-2 Spike (S) protein- or LPS-induced pro-inflammatory zebrafish and co-cultured human cell models, we found that ATG10S significantly reduced the expression of key pro-inflammatory cytokines (IFNA, IFNG, IL1B, IL6, TNF/TNFA, IL8, and CCL2), all transcriptionally regulated by MEF2A (myocyte enhancer factor 2A). Mechanistically, ATG10S bound directly to MEF2A at residues D61/D63, facilitating its selective autolysosomal degradation through MAP1LC3B/LC3B interaction, while it also competed with MAPK7/ERK5 for MEF2A binding to disrupt the TLR4-MAPK7-MEF2A signaling axis. This dual mechanism reduced both MEF2A protein levels and transcriptional activity, thereby attenuating cytokine overproduction. Importantly, ATG10S restored autophagic flux impaired by inflammatory stimuli and exhibited high specificity, sparing unrelated transcription factors. These findings established MEF2A as a critical regulator of the cytokine storm and revealed ATG10S as a distinctive macroautophagy/autophagy-linked immunomodulator that integrated selective autophagic degradation and transcriptional interference. Our study provides mechanistic insight into autophagy-mediated inflammatory regulation and highlights ATG10S as a promising therapeutic candidate for cytokine storm-associated diseases.Abbreviations: ATG: autophagy related; co-IP: co-immunoprecipitation; CQ: chloroquine; dpf: days post-fertilization; ELISA: enzyme-linked immunosorbent assay; hpi: hours post-injection; LC3B: microtubule-associated protein 1 light chain 3 beta; LIR: LC3-interacting region; LPS: lipopolysaccharide; MAPK7/ERK5: mitogen-activated protein kinase 7; MDMs: macrophages; MEF2A: myocyte enhancer factor 2A; MO: morpholino; S: spike protein; SQSTM1: sequestosome 1; TLR4: toll like receptor 4.