Lycorine alleviates intrahepatic cholestasis by regulating bile acid metabolism via TKT/ATF3/BSEP pathway

Cholestatic liver disease (CLD) is defined by impaired bile synthesis and excretion, which in turn results in progressive liver injury or fibrosis, however, there are currently no effective therapeutic drugs. Lycorine is an alkaloid isolated from Lycoris bulbs, exhibiting antiviral, anti-inflammatory, analgesic, and cardioprotective properties. However, there has been no reports concerning its effects on CLD so far. We assessed the hepatoprotective potential of lycorine on intrahepatic cholestasis mouse models induced by α-naphthyl isothiocyanate (ANIT) and multidrug resistance protein 2 knockout (Mdr2^-/-). RNA-sequencing (RNA-Seq), cellular thermal shift assay (CETSA) and mass spectrometry (MS) analysis were used to investigate the underlying molecular mechanisms. Lycorine mitigated intrahepatic cholestasis by downregulating the expression of activating transcription factor 3 (ATF3), a transcriptional repressor of the bile salt export pump (BSEP) that mediates bile acid (BA) secretion. Lycorine directly bound with transketolase (TKT) protein and facilitated its ubiquitin-dependent degradation, thereby disrupting the TKT-ATF3 interaction and subsequently relieved the transcriptional repression of Bsep. Conclusively, our results clarify the protective effects of lycorine against CLD as well as its underlying mechanisms, laying a foundation for the development of novel clinical therapeutic approaches.