Novel strategies for mitigating hepatic ischemia-reperfusion injury: targeting MICU1 and calcium-glycolytic homeostasis with acteoside.

Hepatic ischemia-reperfusion injury (HIRI) contributes to metabolic disorders within hepatic sinusoid and frequently occurs during liver transplantation, yet its underlying mechanisms and intervention strategies remain obscure. This study aimed to elucidate whether acteoside (ACT) improved HIRI by repairing mitochondrial calcium uptake 1 (MICU1)-mediated Ca2+ dysregulation and facilitating glycolytic reprogramming. Using RNA sequencing, cleavage under targets & tagmentation (CUT&Tag) analysis, liver sinusoidal endothelial cells (LSECs)-specific overexpression virus or siMicu1 lipid nanoparticles and ACT derivatives, we explored the hepatoprotective mechanisms of ACT in vivo in HIRI mice and in vitro in hypoxia-reoxygenation or lactate-stimulated LSECs. ACT enhanced endoplasmic reticulum function and restored mitochondrial homeostasis, thereby alleviating LSECs damage and HIRI. Mechanistically, ACT directly bound to MICU1 and inhibited the overflow of Ca2+ from endoplasmic reticulum (ER) to mitochondria and subsequent mitochondrial Ca2+ overload. This competitive binding mode also suppressed MICU1-dependent glycolysis by blocking Ca2+-stimulated lactate production and histone H3K18 lactylation, which epigenetically regulated MICU1 transcription. Notably, ACT synergized with lactate inhibitors or siMicu1 lipid nanoparticles to enhance its anti-HIRI effects, while LSECs-specific Micu1 overexpression abolished these benefits. Structural analysis revealed that the C26/C27/C40/C41 hydroxyl groups determined ACT's MICU1-binding and hepatoprotective activities. This study identifies MICU1 as a central regulator of HIRI and reveals ACT as a targeted therapy by restoring Ca2+ balance and metabolic homeostasis.