Constitutive androstane receptor activation modulates YAP expression and activity through ubiquitination and...

Constitutive Androstane Receptor (CAR) is a member of the nuclear receptor superfamily that significantly contributes to the metabolism of endogenous and exogenous substances and the homeostatic regulation of the body. Yes-associated protein (YAP) is a core component of the Hippo signaling pathway. We have previously demonstrated that CAR activation interacts with YAP and induces the nuclear translocation of YAP, although the specific binding site and regulatory mechanism remain unclear. In this study, we identified the ligand-binding domain (LBD) of CAR as essential for its interaction with YAP, while the WW domain (Tryptophan- Tryptophan domain) of YAP was found to be crucial for CAR binding. We further explored the impact of CAR activation on YAP post-translational modifications. CAR agonism inhibited YAP ubiquitination but promoted its SUMO1 modification, and had no effect on acetylation, glycosylation, and methylation. Notably, CAR activation enhanced the K63-linked ubiquitination of YAP, facilitating its nuclear translocation, and this effect was dependent on the E3 ligase TRAF6. Furthermore, PIAS4 was identified as a key SUMO E3 ligase, promoting YAP SUMO1 modification upon CAR activation. These findings provide new insights into how CAR regulates YAP activity through post-translational modifications, contributing to the understanding of CAR's role in liver regeneration.