Pregnane X receptor, constitutive androstane receptor, or peroxisome proliferator-activated receptor α activation does not affect yes-associated protein phase separation under physiological and hyperosmotic conditions.

Yes-associated protein (YAP) is a critical factor of the Hippo pathway, which plays a key role in regulating organ size. Pregnane X receptor (PXR), constitutive androstane receptor (CAR), and peroxisome proliferator-activated receptor α (PPARα) are key members of the nuclear receptor superfamily, known for mediating diverse physiological and biological processes. Previous studies have demonstrated that activation of PXR, CAR, or PPARα promotes hepatomegaly and liver regeneration via YAP signaling. YAP has been reported to undergo phase separation under hyperosmotic stress, leading to enhanced expression of downstream target genes. However, it remains unknown whether PXR, CAR, or PPARα activation affects the phase separation of YAP. Therefore, this study aimed to investigate the potential effects of PXR, CAR, and PPARα activation on YAP phase separation using live-cell imaging and fluorescence recovery after photobleaching assay. The results suggested that YAP underwent phase separation under hyperosmotic stress in cells, which was associated with increased mRNA and protein expression of YAP target genes. Further live-cell imaging revealed that neither PXR, CAR, nor PPARα activation induced YAP phase separation under physiological conditions or affected its phase separation under hyperosmotic stress. In conclusion, these findings demonstrate that activation of PXR, CAR, or PPARα does not induce YAP phase separation under physiological conditions or under hyperosmotic stress. SIGNIFICANCE STATEMENT: Yes-associated protein (YAP) plays a crucial role in regulating organ size. Activation of pregnane X receptor, constitutive androstane receptor, or peroxisome proliferator-activated receptor α promotes hepatomegaly and liver regeneration via YAP signaling. This study demonstrates that activation of pregnane X receptor, constitutive androstane receptor, and peroxisome proliferator-activated receptor α does not induce YAP phase separation under either physiological conditions or hyperosmotic stress, which contributes to further understanding of the regulatory mechanisms involving pregnane X receptor, constitutive androstane receptor, peroxisome proliferator-activated receptor α, and YAP, providing new insights into their physiological functions.