Wnt5a Induces Collagen Production by Human Periodontal Ligament Cells Through TGFβ1‐Mediated Upregulation of Periostin Expression

Abstract

Wnt5a, a member of the noncanonical Wnt proteins, is known to play important roles in the development of various organs and in postnatal cell functions. However, little is known about the effects of Wnt5a on human periodontal ligament (PDL) cells. In this study, we examined the localization and potential function of Wnt5a in PDL tissue. Immunohistochemical analysis revealed that Wnt5a was expressed predominantly in rat PDL tissue. Semi-quantitative reverse-transcription polymerase chain reaction and Western blotting analysis demonstrated that human PDL cells (HPDLCs) expressed Wnt5a and its receptors (Ror2, Fzd2, Fzd4, and Fzd5). Removal of occlusal pressure by extraction of opposing teeth decreased Wnt5a expression in rat PDL tissue, and the expression of Wnt5a and its receptors in HPDLCs was upregulated by exposure to mechanical stress. Stimulation with Wnt5a significantly enhanced the proliferation and migration of HPDLCs. Furthermore, Wnt5a suppressed osteoblastic differentiation of HPDLCs cultivated in osteogenic induction medium, while it significantly enhanced the expression of PDL-related genes, such as periostin, type-I collagen, and fibrillin-1 genes, and the production of collagen in HPDLCs cultivated in normal medium. Both knockdown of periostin gene expression by siRNA and inhibition of TGFβ1 function by neutralizing antibody suppressed the Wnt5a-induced PDL-related gene expression and collagen production in HPDLCs. Interestingly, in HPDLCs cultured with Wnt5a, TGFβ1 neutralizing antibody significantly suppressed periostin expression, while periostin siRNA had no effect on TGFβ1 expression. These results suggest that Wnt5a expressed in PDL tissue plays specific roles in inducing collagen production by PDL cells through TGFβ1-mediated upregulation of periostin expression.

Promotion of periostin expression contributes to the migration of Schwann cells

“…From our results, it is very possible that these effects are mediated through periostin. In recent experiments, it has been shown that Wnt5a can also upregulate periostin expression but seems to exert this upregulation solely through augmentation of TGFβ-1 levels (Hasegawa et al, 2015). The connection between neuregulins and the expression level of periostin, as well as our preliminary data on nerve regeneration, are exciting as a recent paper shows that re-expression of neuregulins after injury to Schwann cells is highly important for regeneration and remyelination (Stassart et al, 2013).…”

Role of the Wnt signaling molecules in the tooth

“…Other reports have suggested a similar function for Wnt5a because knockdown of Wnt5a in human PDL stem cells enhanced the ALP activity induced by osteoinductive medium, in which canonical Wnt signaling may be activated [76]. Wnt5a reportedly suppresses osteogenic-related markers of human PDL cells cultured by osteogenic induction medium [77]. Conversely, Wnt5a signaling functions as a positive regulator in dental follicle cell differentiation triggered by BMP-2 [78], suggesting that the function of Wnt5a may depend on the state of the cell.…”

Transgelin mediates transforming growth factor‐β1‐induced proliferation of human periodontal ligament cells

“…In addition, HPDLCs from all three donors expressed TGFB1 mRNA, and phosphorylation of Smad2/3 was slightly detected in HPDLCs without stimulation, demonstrating that endogenous TGF‐β1 activates TGF‐β/Smad signaling in autocrine or paracrine manners. TGF‐β1 enhances various PDL cellular processes including proliferation, migration and collagen expression . In this study, because TGF‐β1 treatment enhanced proliferation and collagen production of HPDLCs (data not shown), we examined whether transgelin expression is involved in such TGF‐β1 effects on PDL cells.…”