Ubiquitin C-terminal hydrolase L1 activation in periodontal ligament cells mediates orthodontic tooth movement via the MAPK signaling pathway

Abstract

ABSTRACT Purpose Periodontal ligament cells (PDLCs) play a significant role in orthodontic force induced bone remodeling. However, the molecular mechanisms by which PDLCs respond to mechanical stimuli and influence osteoclastic activities remain unclear. This study aims to investigate the role of UCHL1, a key deubiquitinating enzyme involved in protein degradation and cellular responses, in force-treated PDLCs during orthodontic tooth movement (OTM). Materials and Methods In this study, we conducted in vivo and in vitro experiments using human PDLCs and a rat model of OTM. Mechanical stress was applied to PDLCs, and UCHL1 expression was analyzed through quantitative real-time polymerase chain reaction (qPCR), Western blot, and immunofluorescence staining. UCHL1 knockdown was achieved using siRNA, and its effects on osteoclast differentiation were assessed. The role of the MAPK/ERK pathway was investigated using the MEK-specific inhibitor U0126. An animal model of OTM was established, and the impact of UCHL1 inhibitor-LDN57444 on OTM and osteoclastic activity was evaluated through micro-CT analysis, histological staining, and immunohistochemistry. Results Mechanical force induced UCHL1 expression in PDLCs during OTM. UCHL1 knockdown downregulated the RANKL/OPG ratio in PDLCs, affecting osteoclast differentiation. LDN57444 inhibited OTM and osteoclastic activity. UCHL1 activation correlated with ERK1/2 phosphorylation in force-treated PDLCs. Conclusions Mechanical force mediated UCHL1 activation in PDLCs promotes osteoclast differentiation via the ERK1/2 signaling pathway during OTM.