Mesenchymal β-catenin signaling affects palatogenesis by regulating α-actinin-4 and F-actin

Objective: Our previous research have found that mesenchymal beta-catenin may be involved in palatal shelf (PS) elevation by regulating F-actin. Here, we further investigated the exact mechanism of beta-catenin/F-actin in the PS mesenchyme to regulate palatal reorientation. Materials and Methods: (1) Firstly, Ctnnb1(ex3f)(beta-catenin) mice were conditionally overexpressed in the palatal mesenchyme by crossing with the Sox9-creER(T2) mice (induced by Tamoxifen injections); (2) Subsequently, histology and immunohistochemistry were used to characterize the variations of PS morphology and expression of key molecules associated with developmental process; (3) Finally, experiments in vivo and ex vivo were employed to identify the critical mechanisms in beta-catenin silenced and overexpressed models. Results: We found that the Sox9CreER; Ctnnb1(ex3f) mice exhibited failed palatal elevation and visible cleft palate, and overexpression of beta-catenin disturbed the F-actin responsible for cytoskeletal remodeling in palatal mesenchymal cells. qRT-PCR results showed mRNA levels of alpha-actinin4, a gene involved in F-actin cross-linking, were associated with knockdown or overexpression of beta-catenin in ex vivo, respectively. Experiments in vivo revealed that mesenchymal specific inactivation or overexpression of beta-catenin exhibited decreased or increased alpha-actinin-4 expression. Conclusions: Mesenchymal beta-catenin/F-actin plays an essential role in PS reorientation, which mediate alpha-actinin-4 to regulate F-actin cytoskeleton reorganization.

Automated summary

In this study, we investigated the exact mechanism of beta-catenin/F-actin in regulating palatal reorientation. We found that overexpression of beta-catenin disrupted F-actin responsible for cytoskeletal remodeling in palatal mesenchymal cells, leading to failed palatal elevation and visible cleft palate. Furthermore, we identified alpha-actinin-4 as a key mediator in the regulation of F-actin cytoskeleton reorganization by beta-catenin.