Prostaglandin E 2 maintains mouse ESC undifferentiated state through regulation of connexin31, connexin43 and connexin45 expression: Involvement of glycogen synthase kinase 3β/β-catenin

摘要

Background information: Although previous reports have examined the function of prostaglandin E 2 (PGE 2) on gap junctions and undifferentiated stem cells, its effects on the reciprocal action of connexin (Cx) isoforms and undifferentiation in embryonic stem cells (ESCs) are unclear. Therefore, we investigated the role of PGE 2 on Cx isoforms and maintenance of mouse ESC undifferentiated state. Results: We have analysed 10 Cx genes, but found nine of them. PGE 2 (50μM) stimulated Cx31, Cx32, Cx40, Cx43 and Cx45 mRNA expression. Amongst them, PGE 2 maximally stimulated the Cx43 mRNA expression and gap junction inter-cellular coupling. Therefore, we investigated the effect of PGE 2 on Cx43 expression. PGE 2 activated cAMP/protein kinase A (PKA) and phosphatidylinositol 3-kinase (PI3K)/Akt phosphorylation. In addition, treatments of adenylate cyclase activators increased Cx43 expression, but not PI3K/Akt phosphorylation. PGE 2 also inactivated GSK-3β and stimulated active-β-catenin. Furthermore, a ChiP assay demonstrated the association of β-catenin with the Cx26 (as control) and Cx43 promoter. Finally, down-regulation of PGE 2-induced Cx isoforms by AH 6809, Cx31-, Cx43-, Cx45 small interfering (si)RNA and 18α-glycyrrhetinic acid decreased levels of undifferentiated markers of ESCs, including Oct4, FoxD3, Sox2 and SSEA-1, but Nanog did not be down-regulated by Cx43 siRNA. Conclusions: PGE 2 stimulates Cx isoforms via GSK-3β/β-catenin via EP2-receptor-dependent cAMP/PKA and PI3K/Akt in mouse ESCs, thereby partially contributing to the maintenance of their undifferentiated state. Although ESCs experiments have focused on differentiation studies, only few researches about effect of extracellular factors in cellular junction and pluripotency of ESC have been performing. Therefore, we investigated the effect of PGE 2 on connexin isoforms and undifferentiated state on mouse ESCs. This result shows that PGE 2 stimulates Cx43 expression in mouse ESCs, thereby partially contributing to the maintenance of their undifferentiated state.