A miR-382-5p-PORCN axis modulates endogenous Wnt signaling during palatal development

Precise temporal regulation of Wnt signaling is required for normal palate development, but the mechanisms controlling endogenous Wnt ligand availability during palatogenesis remain poorly understood. Here, temporal microRNA profiling of mouse palatal shelves from embryonic day (E) 13.5 to E15.0 identified miR-382-5p as a dynamically regulated microRNA exhibiting a pronounced but transient decrease at E14.5, a critical stage of palatal shelf apposition. Bioinformatic analysis identified Porcn, an essential regulator of Wnt ligand maturation and secretion, as a candidate target of miR-382-5p. Direct targeting was confirmed by dual-luciferase reporter assays. Overexpression of miR-382-5p reduced PORCN protein abundance without affecting Porcn mRNA levels, indicating post-transcriptional repression. Consistent with reduced PORCN activity, miR-382-5p attenuated endogenous Wnt signaling, as evidenced by decreased Axin2 and Ccnd1 expression and reduced TOP/FOP reporter activity. Importantly, responsiveness to exogenous Wnt3a remained intact, and restoration of PORCN expression using a miRNA-insensitive Porcn coding sequence significantly rescued Wnt signaling activity. Together, these findings identify Porcn as a direct target of miR-382-5p and establish a previously unrecognized miR-382-5p-PORCN-Wnt regulatory axis. The transient decrease of miR-382-5p at E14.5 suggests that developmental relief of Porcn repression may contribute to stage-specific enhancement of endogenous Wnt signaling during palatogenesis.