Wnt signalling is a highly conserved signalling pathway that plays an important role in a variety of biological processes. Frizzled (Fzd) family proteins are receptors for Wnt ligands. The physiological processes involved in mature trafficking of Fzd proteins remain elusive. Here, we identified asparagine residues 59 and 144 as the N-glycosylation modification sites of Fzd4. Sequence analysis of Fzd4 in different species showed that the two asparagine residues were highly conserved. N-glycosylation modification of Fzd4 is indispensable for its maturation and transport to the plasma membrane. N-glycosylation modification enhances the stability of Fzd4 and is also necessary for Fzd4 activity, which promotes Fzd4 interaction with Wnt ligands and co-receptor Norrin. Knockout of Fzd4 in the non-small cell lung cancer (NSCLC) cell line A549 followed by replenishment of Fzd4 glycosylation site mutants inhibited the growth and migration ability of A549 cells in vitro and in vivo. In summary, we identified N-glycosylation modification sites of Fzd4. N-glycosylation modification of Fzd4 is necessary for its stability and activity. When N-glycosylation modification is absent, Fzd4 cannot mediate the Wnt/β-catenin signalling pathway, which can inhibit the proliferation and migration of NSCLC and provide new targets and strategies for the treatment of NSCLC.
Xiaocen Zhang,Maolin Chang,Beike Wang,Xiaoyu Liu,Zhen Zhang,Guangli Han
Objective To verify the role of YAP/WNT5A/FZD4 axis in stretch-induced osteogenic differentiation of hPDLCs. Background During orthodontic tooth movement, differentiation of human periodontal ligament cells (hPDLCs) at the tension side of the periodontal ligament mediates new bone formation. WNT5A promotes osteogenesis and its regulator Yes-associated protein (YAP) is responsive to mechanical stimulation in hPDLCs. However, the mechanisms of YAP and WNT5A in alveolar bone remodeling remain unclear. Methods Cyclic stretch was applied to hPDLCs to mimic the orthodontic stretching force. Osteogenic differentiation was determined by alkaline phosphatase (ALP) activity, Alizarin Red staining, qRT-PCR and western blotting. To detect activation of YAP and expression of WNT5A and its receptor Frizzled-4 (FZD4), western blotting, immunofluorescence, qRT-PCR and ELISA were performed. Verteporfin, Lats-IN-1, small interfering RNAs and recombinant protein were used to explore the relationship of YAP, WNT5A and FZD4, and the effect of their relationship on stretch-induced osteogenesis of hPDLCs. Results WNT5A, FZD4 and nuclear localization of YAP were upregulated by cyclic stretch. YAP positively regulated WNT5A and FZD4 expression and osteogenic differentiation of hPDLCs under cyclic stretch by YAP inhibition or activation assay. Knockdown of WNT5A and FZD4 attenuated YAP-induced and stretch-induced osteogenic differentiation. Recombinant WNT5A rescued the suppressed osteogenic differentiation by YAP inhibitor in hPDLCs, whereas knockdown of FZD4 weakened the effect of WNT5A and amplified the suppression. Conclusions WNT5A/FZD4 could be positively regulated by YAP and the YAP/WNT5A/FZD4 axis mediated osteogenic differentiation of hPDLCs under cyclic stretch. This study provided further insight into the biological mechanism of orthodontic tooth movement.
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