Previous studies have shown that nuclear binding protein 2 (NUCB2) is expressed in the human placenta and increases with an increase in the syncytialization of trophoblast cells. This study aimed to investigate the role of NUCB2 in the differentiation and fusion of trophectoderm cells. In this study, the expression levels of NUCB2 and E-cadherin in the placentas of rats at different gestation stages were investigated. The results showed that there was an opposite trend between the expression of placental NUCB2 and E-cadherin in rat placentas in different trimesters. When primary human trophoblast (PHT) and BeWo cells were treated with high concentrations of Nesfatin-1, the trophoblast cell syncytialization was significantly inhibited. The effects of NUCB2 knockdown in BeWo cells and Forskolin-induced syncytialization were investigated. These cells showed a significantly decreased cell fusion rate. The mechanism underlying NUCB2-regulated trophoblast cell syncytialization was explored using RNA-Seq and the results indicated that the epidermal growth factor receptor (EGFR)-phospholipase C gamma 1 (PLCG1)-calmodulin-dependent protein kinase IV (CAMK4) pathway might be involved. The results suggested that the placental expression of NUCB2 plays an important role in the fusion of trophoblasts during differentiation via the EGFR-PLCG1-CAMK4 pathway.
Keywords: EGFR/PLCG1/CAMK4; NUCB2/Nesfatin-1; embryonic development; placenta; trophoblast fusion.