Expression of UNCL during development of periodontaltissue and response of periodontal ligament fibroblaststo mechanical stress in vivo and in vitro

Abstract

Mutations in two genes, uncoordinated (unc) anduncoordinated-like (uncl), lead to a failure of mechanotransductionin Drosophila. UNCL, the human homolog ofunc and uncl, is preferentially expressed in periodontalligament (PDL) fibroblasts compared with gingival fibroblasts.However, the precise role of UNCL in the PDLremains unclear. The aim of the present study has been toexamine whether mechanical stimuli modulate the expressionof UNCL in the human PDL in vivo and in vitro and toexamine the roles of UNCL in the development, regeneration,and repair of the PDL. We have investigated theexpression pattern of UNCL during the development ofperiodontal tissue and the response of PDL fibroblasts tomechanical stress in vivo and in vitro. The expression ofUNCL mRNA and protein increases with PDL fibroblastdifferentiation from the confluent to multilayer stage butslightly decreases on mineralized nodule formation. UNCLhas also been localized in ameloblasts and adjacent cells,differentiating cementoblasts, and osteoblasts of the developingtooth. Strong distinct UNCL expression has furtherbeen observed in the differentiating cementoblasts of thetooth periodontium at the site of tension afterthodontictooth movement. Application of cyclic mechanical stress onPDL fibroblasts increases the expression of UNCL mRNA.These results indicate that UNCL plays important roles inthe development, differentiation, and maintenance ofperiodontal tissues and also suggest a potential role ofUNCL in the mechanotransduction of PDL fibroblasts.