HELLS Reduction Contributes to Compressive Force-Induced Functional Changes in PDLSCs

Area of Science:

• Biomedical Engineering
• Stem Cell Biology
• Epigenetics

Background:

• Orthodontic tooth movement (OTM) relies on bone remodeling, but the cellular sensing of mechanical forces is unclear.
• Periodontal ligament stem cells (PDLSCs) are key players in this process, responding to mechanical stimuli.

Purpose of the Study:

• To identify molecular mechanisms in human PDLSCs (hPDLSCs) responding to mechanical forces.
• To investigate the role of the epigenetic regulator HELLS as a mechanosensitive mediator in hPDLSCs during OTM.

Main Methods:

• Compressive force applied to hPDLSCs in vitro and in a mouse OTM model.
• HELLS expression analyzed via qPCR and Western blotting.
• Functional assays including Alizarin Red S staining and alkaline phosphatase activity.
• siRNA-mediated HELLS knockdown to assess effects on differentiation and gene expression.
• Transcriptomic analysis to identify affected pathways.
• Co-culture assays with RAW264.7 cells to evaluate osteoclastogenesis.
• E2F1 identified as a potential transcription factor.

Main Results:

• Compressive force significantly downregulated HELLS expression in hPDLSCs.
• HELLS knockdown impaired osteogenic differentiation and altered mechanotransduction pathways.
• HELLS deficiency increased YAP and RANKL expression.
• Osteoclast differentiation was enhanced in co-cultured cells upon HELLS knockdown.
• E2F1 was identified as a transcription factor involved in HELLS regulation.

Conclusions:

• HELLS acts as a mechano-epigenetic regulator in hPDLSCs.
• Force-induced HELLS downregulation contributes to alveolar bone remodeling during OTM.
• This downregulation influences OTM by reducing osteogenesis and increasing pro-osteoclastogenic signaling.