Background/purpose: Human periodontal ligament consists of elastic system fibers, mainly fibrillin-1 (FBN1). Periostin (POSTN) maintains periodontal homeostasis. A previous study showed that the expression of Postn in periodontal ligament cells was decreased in mice underexpressing Fbn1. However, the relationship between FBN1 and POSTN is not fully understood in the context of mechanical stress. FBN1 contributes to transforming growth factor β1 (TGF-β1) activation; TGF-β1 upregulates the expression of POSTN in human periodontal ligament cells. This study examined whether FBN1 contributed to the maintenance of periodontal homeostasis in cultured human periodontal ligament cells.
Materials and methods: Human periodontal ligament fibroblasts (HPDLFs) were exposed to mechanical force via centrifugation. The expression of POSTN was examined by quantitative reverse transcription polymerase chain reaction. The phosphorylation of Smad2 in the TGF-β/Smad signaling pathway was monitored by western blotting.
Results: The expression levels of FBN1 and POSTN were not significantly decreased by centrifugation. However, the expression of POSTN after centrifugation significantly decreased upon knockdown of FBN1. The phosphorylation of Smad2 after centrifugation was decreased, regardless of FBN1 knockdown. Supplementation with 0.1 ng/ml recombinant human TGF-β1 rescued POSTN expression after centrifugation in HPDLFs upon knockdown of FBN1.
Conclusion: FBN1 regulates the expression of POSTN to maintain periodontal homeostasis via TGF-β/Smad signaling during centrifugation.
Keywords: Fibrillin-1; Human periodontal ligament fibroblasts; Periodontal homeostasis; Periostin; TGF-β1.
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