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Published on: April 15, 2021
Analysis of Circadian Gene Expression in Periodontal Ligament Cells During Orthodontic Force Application
1Department of Oral and Maxillofacial Diagnostic Sciences, College of Dentistry, Taibah University, Al Madinah Al Munawara, Kingdom of Saudi Arabia.
Background:
Circadian genes regulate biological rhythms and are increasingly recognized for their role in bone remodeling. Periodontal ligament (PDL) cells respond dynamically to orthodontic forces, and the influence of circadian gene oscillations on this response remains unclear.
Methods:
Primary hPDLFs were cultured and exposed to a 2 g/cm² compressive force using a Flexcell FX-5000 system for 24 hours. Samples were collected at 0, 6, 12, 18, and 24 hours. Quantitative RT-PCR was used to assess circadian gene expression. GAPDH was used as a housekeeping gene. Expression levels were normalized and compared using one-way ANOVA with post hoc Tukey tests.
Results:
BMAL1 and CLOCK showed significant rhythmic upregulation with peak expression at 12 hours (BMAL1: 2.31 ± 0.41-fold; CLOCK: 2.10 ± 0.36-fold; P < 0.01), while PER1 and CRY1 peaked at 18 hours (PER1: 2.44 ± 0.39-fold; CRY1: 2.13 ± 0.33-fold; P < 0.01). A strong inverse correlation was observed between BMAL1 and PER1 expression (r = -0.76, P = 0.002).
Conclusion:
Circadian genes in PDL cells demonstrate time-dependent expression under orthodontic force, suggesting a regulatory role in mechanotransduction and tissue remodeling. Chronotherapy could potentially optimize orthodontic outcomes by aligning force application with biological rhythms.
