miR-27b-5p inhibits BeWo cells fusion by regulating WNT2B and enzyme involved in progesterone synthesis

Problem: The miRNAs show placenta-specific expression patterns, which alter during pregnancy-related complications. In present study, the role of miR-27b-5p during forskolin-mediated BeWo cells fusion has been investigated. Method of Study: The fusion of BeWo cells in response to forskolin treatment (25 µM) was studied by desmoplakin I+II staining. Expression profile of miR-27b-5p by qRT-PCR and its targets HSD3β1 and WNT2B by qRT-PCR and in Western blot were studied. The effect of overexpression of miR-27b-5p and silencing of HSD3β1 & WNT2B by siRNA on forskolin-mediated BeWo cells fusion and secretion of hCG and progesterone by ELISA was investigated. Results: Time-dependent down-regulation in the expression of miR-27b-5p in forskolin-treated BeWo cells has been confirmed by qRT-PCR. Overexpression of miR-27b-5p significantly inhibits forskolin-mediated BeWo cells fusion as well as hCG & progesterone secretion. HSD3β1 and WNT2B were identified as targets of miR-27b-5p and are up-regulated in forskolin-treated BeWo cells. Overexpression of miR-27b-5p in BeWo cells downregulates their expression. Further, luciferase reporter assay revealed that miR-27b-5p directly target expression of both HSD3β1 and WNT2B. Silencing of both HSD3β1 and WNT2B leads to a significant reduction in forskolin-mediated BeWo cells fusion with concomitant decrease in the secretion of progesterone or/and hCG. Decrease in forskolin-mediated cells fusion observed in miR-27b-5p mimic transfected BeWo cells could be rescued by the overexpression of both HSD3β1 and WNT2B. Conclusion: These observations suggest that reduced miR-27b-5p in forskolin-treated BeWo cells leads to increased secretion of progesterone and hCG due to loss of repressional control on HSD3β1 and WNT2B.