Abstract
in English, Chinese Somatic cell nuclear transfer (SCNT) has been successfully employed across various mammalian species, yet cloned animals consistently exhibit low pregnancy rates, primarily due to placental abnormalities such as hyperplasia and hypertrophy. This study investigated the involvement of the Hippo signaling pathway in aberrant placental development in SCNT-induced bovine pregnancies. SCNT-derived cattle exhibited placental hypertrophy, including enlarged abdominal circumference and altered placental cotyledon morphology. RNA sequencing analysis indicated significant dysregulation of Hippo signaling pathway genes in SCNT placentas. Co-expression of YAP1 and CCND1 was observed in cloned blastocysts, placental tissues, and bovine placental mesenchymal stem cells (bPMSCs). Manipulation of YAP1 expression demonstrated the capacity to regulate bPMSC proliferation. Experimental assays confirmed the direct binding of YAP1 to CCND1, which subsequently promoted CCND1 expression in bPMSCs. Furthermore, inhibition of CDK6, a downstream target of CCND1, attenuated SCNT bPMSC proliferation. This study identified YAP1 as a key regulatory component within the Hippo signaling pathway that drives placental hyperplasia in cloned cattle through up-regulation of CCND1-CDK6 expression, facilitating cell cycle progression. These findings offer potential avenues for enhancing cloning efficiency, with implications for evolutionary biology and the conservation of valuable germplasm resources. 体细胞核移植（SCNT）已成功应用于多种哺乳动物，克隆动物的低妊娠率与胎盘增生和肥大密切相关。该研究以克隆牛和对照牛胎盘为研究对象，探讨了Hippo信号通路调控因子YAP1在SCNT牛胎盘中的调控机制。研究发现，SCNT牛妊娠期间表现出胎盘肥大现象，包括腹围增大和胎盘子叶体积增大等方面的改变。通过对克隆牛和对照牛胎盘组织的RNA-seq分析显示，SCNT胎盘中的Hippo信号通路基因YAP1存在表达异常。进一步研究发现，YAP1和CCND1在克隆囊胚、胎盘组织和牛胎盘间充质干细胞（bPMSCs）中共表达。并且，调控YAP1的表达可影响bPMSCs的增殖。进一步研究证实了YAP1与CCND1直接结合，进而促进CCND1在bPMSCs中的表达，抑制CDK6（CCND1的下游靶标）可降低SCNT bPMSCs的增殖能力和细胞周期。综上所述，该研究发现Hippo信号通路中的YAP1通过调控CCND1-CDK6的表达影响胎盘细胞增殖和细胞周期，进而调控克隆牛的胎盘增生。这项研究系统揭示了克隆牛胎盘肥大的调控机制，为提高动物克隆效率提供了提供参考。.