MANF attenuates cholestatic liver injury by altering GRP78-PERK association.

Cholestatic liver injury (CLI) arises from hepatic bile acid overload due to impaired bile flow, often progressing to liver fibrosis and even failure. While endoplasmic reticulum (ER) stress activation is a key driver for CLI pathogenesis, its regulatory mechanisms remain incompletely understood. In this study, we identify that mesencephalic astrocyte-derived neurotrophic factor (MANF), as an ER-resident protein, was markedly upregulated within the livers of both CLI patients and murine models. In rodents with bile duct ligation (BDL)-triggered cholestasis, hepatic-specific MANF knockout aggravated bile acid overload, liver injury, and inflammation by hyperactivating ER stress. Furthermore, hepatic-specific MANF deletion exacerbated tunicamycin-induced ER stress and hepatocyte damage, whereas hepatic MANF overexpression conferred protection against ER stress and liver injury. Mechanistically, MANF directly interacts with GRP78, altering the association between GRP78 and PERK and thereby inhibiting PERK-eIF2α-ATF4 pathway activation. Disruption of the GRP78-PERK axis abolished MANF-mediated ER stress attenuation. Hepatic MANF overexpression mitigated BDL-induced liver damage via deactivating PERK-ATF4 signaling. Our studies unveil MANF serving as a pivotal regulator of ER stress in CLI, functioning through the GRP78-PERK-ATF4 axis. These results not only provide novel mechanistic insights into cholestatic liver injury but also position MANF as a potential candidate therapeutic target for CLI.