Analysis of Circadian Gene Expression in Periodontal Ligament Cells During Orthodontic Force Application

No SJR dataJan 12, 2026Journal of pharmacy & bioallied sciences

Daily Patterns of Gene Activity in Ligament Cells During Orthodontic Pressure

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Abstract

Circadian genes in periodontal ligament cells show significant rhythmic upregulation, with peak expression at 12 hours under compressive force.

Peak expression of BMAL1 and CLOCK occurred at 12 hours, showing a 2.31 ± 0.41-fold increase.
PER1 and CRY1 exhibited peak expression at 18 hours, with increases of 2.44 ± 0.39-fold.
An inverse correlation of -0.76 was found between BMAL1 and PER1 expression levels.
The findings indicate that circadian gene expression in PDL cells is time-dependent when subjected to orthodontic forces.
may play a role in and tissue remodeling processes in bone.

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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 withTukey tests. post hoc

RESULTS: andshowed significant rhythmic upregulation with peak expression at 12 hours (2.31 ± 0.41-fold;: 2.10 ± 0.36-fold;< 0.01), whileandpeaked at 18 hours (2.44 ± 0.39-fold;2.13 ± 0.33-fold;< 0.01). A strong inverse correlation was observed betweenandexpression (= -0.76,= 0.002). BMAL1CLOCK BMAL1: CLOCK P PER1CRY1PER1: CRY1: P BMAL1PER1r P

CONCLUSION: Circadian genes in PDL cells demonstrate time-dependent expression under orthodontic force, suggesting a regulatory role in and tissue remodeling. Chronotherapy could potentially optimize orthodontic outcomes by aligning force application with biological rhythms.