Abstract TP283: Histone Lactylation and Neuronal Autophagy: Insights Into the Penumbra-Core Transition and Potential Biomarker in Ischemic Stroke

Abstract

Objectives: The dynamic evolution of ischemic penumbra to core has implications for stroke outcomes. Optimizing outcomes remains challenging despite advanced recanalization. We examined the intricate molecular interplay between lactylation and RNA m6A modifications, to unravel the H3K18la-Tfeb m6A-autophagy-neuron-injury pathway, understanding mechanisms underlying penumbra-core transition and investigating potential biomarkers indicative of injury severity. Method: Adult SD rats underwent 2, 6, and 24 h of middle cerebral artery occlusion (MCAO) and subsequent reperfusion. The penumbra-core transition-induced brain damage was quantified by infarct volume post 48 h of reperfusion. Employing CUT&Tag and ChIP, H3K18la enrichment in promoter regions was identified. The mRNA and protein levels of lactylation, methyltransferase like 3 (METTL3), transcription factor EB (TFEB) and autophagy-related molecules (LC3, P62, LAMP1) were examined. METTL3 and TFEB localization was determined using immunofluorescence, while serum H3K18la levels were analyzed. Result: Ischemia duration was directly linked to elevated neuronal lactylation, particularly H3K18la, and autophagy. Increased H3K18la enrichment was observed in Mettl3 promoter regions, promoting Mettl3 gene transcription. This leads to METTL3-induced tfeb m6A modifications, enhancing TFEB expression and its nuclear translocation. Administering C646 (lactylation writer inhibitor) suppressed METTL3, TFEB, LC3, P62, and LAMP1 expressions, which mitigated brain injuries, underlining lactylation's key role in excessive neuronal autophagy initiation. All molecular alterations were strongly tied to the penumbra-core transition. Markedly, ischemic rats presented elevated serum H3K18la levels, which correlated with dynamic neurological damage. Conclusion: Our study elucidates molecular dynamics driving the penumbra-core transition in ischemic stroke. H3K18la initiatives METTL3-associated tfeb m6A modifications, activating the autophagy-lysosome pathway, thus enhancing autophagy and neuronal death. Serum H3K18la variations emerge as potential indicators of neuronal damage severity, suggesting effective biomarkers for assessing post-stroke prognosis.