Abstract
Neuronal loss in neurodegenerative disease is driven in part by maladaptive stress signaling and impaired adaptation to proteotoxic challenges. ENL and AF9 are YEATS-domain acyl-lysine reader proteins best characterized in leukemia, but their functions in neurons remains unclear. Here, we defined the role of the ENL/AF9 YEATS domain using complementary chemical and genetic perturbations. We applied the selective YEATS inhibitor SR-0813 in differentiated human neurons and modulated ENL/AF9 activity in Drosophila using either SR-0813 or ENL/AF9 knockdown. In flies, SR-0813 phenocopied ENL/AF9 knockdown by extending lifespan and enhancing stress tolerance. To test disease-context specificity, we performed a Drosophila genetic modifier screen across neurodegeneration models. ENL/AF9 reduction was beneficial in UBQLN2P497H and SOD1G94A but showed reduced efficacy or became detrimental in chronic aggregation or mitochondrial stress models such as (GGGGCC)49 and polyQ disease. In human neurons, SR-0813 improved survival across multiple stress conditions, with the strongest protection during endoplasmic reticulum stress. Mechanistically, ENL/AF9 YEATS inhibition dampened PERK-dependent integrated stress response signaling and reduced apoptotic commitment without broadly enhancing proteostasis capacity. Together, these findings identified ENL/AF9 as modulators of neuronal stress-response dynamics and established ENL/AF9 YEATS-domain inhibition as a context-dependent strategy to enhance neuronal resilience with relevance to ALS and related proteotoxic disorders.