Maternal Hepatocytes Heterogeneously and Dynamically Exhibit Developmental Phenotypes Partially via YAP1 during Pregnancy

Background and Aims Pregnancy induces reprogramming of maternal physiology to support fetal development and growth. Maternal hepatocytes undergo hypertrophy and hyperplasia to drive maternal liver growth and alter their gene expression profiles simultaneously. This study aimed to further understand maternal hepatocyte adaptation to pregnancy. Methods Timed pregnancies were generated in mice. Results In a non-pregnant state, most hepatocytes expressed Cd133, α-fetalprotein ( Afp ,) and epithelial cell adhesion molecule ( Epcam ) mRNAs, whereas overall, at the protein level, they exhibited a CD133 - /AFP - phenotype; however, pericentral hepatocytes were EpCAM + . As pregnancy advanced, while most maternal hepatocytes retained Cd133, Afp , and Epcam mRNA expression, they generally displayed a phenotype of CD133 + /AFP + , and EpCAM protein expression was switched from pericentral to periportal maternal hepatocytes. In addition, we found that the Hippo/yes-associated protein (YAP) pathway does not respond to pregnancy. Yap1 gene deletion specifically in maternal hepatocytes did not affect maternal liver growth or metabolic zonation. However, the absence of Yap1 gene eliminated CD133 protein expression without interfering with Cd133 transcript expression in maternal livers. Conclusions We demonstrated that maternal hepatocytes acquire heterogeneous and dynamic developmental phenotypes, resembling fetal hepatocytes, partially via YAP1 through a post-transcriptional mechanism. Moreover, maternal liver is a new source of AFP. In addition, maternal liver grows and maintains its metabolic zonation independent of the Hippo/YAP1 pathway. Our findings revealed a novel and gestation-dependent phenotypic plasticity in adult hepatocytes. Synopsis We found that maternal hepatocytes exhibit developmental phenotypes in a temporal and spatial manner, similarly to fetal hepatocytes. They acquire this new property partially via yes-associated protein 1.