Autophagy promotes excessive trophoblast differentiation via YAP nuclear localization in a BiCHM patient-specific iPSC model

Biparental complete hydatidiform mole (BiCHM) is the autosomal-recessive familial subtype of complete hydatidiform mole caused by homozygous or complex heterozygous mutations of particular maternal-effect genes. NLRP7 mutations are the major cause and are detected in 48%–80% of BiCHM patients. Since mice lack the NLRP7 gene, studying pathogenic mechanisms during embryogenesis is largely hampered by the lack of disease models. Here, we conducted trophoblast differentiation on BiCHM patient-derived human induced pluripotent stem cells (hiPSCs) carrying the NLRP7 homozygous mutation (Gln421Ter) to establish a human-based BiCHM model in vitro . RNA sequencing analysis revealed that BiCHM patient-specific hiPSC-derived trophoblasts exhibit a distinct transcriptome profile. Notably, BiCHM patient-specific hiPSC-derived trophoblasts recapitulated pathogenic phenotypes of hydatidiform mole, including excessive trophoblast differentiation, enhanced capacity of β-human chorionic gonadotropin (β-HCG) secretion, and differential expression of imprinted genes. Mechanistically, aberrant activation of autophagy occurs in BiCHM undifferentiated hiPSCs, which promotes nuclear translocation of yes-associated protein (YAP) and excessive trophoblast differentiation. Pharmacological activation of autophagy in control undifferentiated hiPSCs caused increased nuclear translocation of YAP and excessive trophoblast differentiation. Pharmacological inhibition of YAP in BiCHM undifferentiated hiPSCs effectively rescued the excessive trophoblast differentiation phenotype. Moreover, immunohistochemistry analysis revealed markedly increased expression of the autophagy marker p62 in molar tissues compared with first-trimester villous tissues, thus enhancing the clinical relevance of our study. In conclusion, our study establishes the previously undescribed autophagy–YAP–excessive trophoblast differentiation axis in BiCHM and sheds light on the application of targeting YAP for BiCHM therapeutics.