KEAP1-NRF2-IKKβ crosstalk protects periodontal ligament fibroblasts subjected to mechanical vibratory forces

Abstract

Objectives: When cells experience acute trauma from forces, cytoprotective molecules such as NRF2 and activation of inflammatory pathways led by NFkB are synthesized and released. An action-binding protein, KEAP1, plays a central role in these activities. The present study aimed to determine the effect of differential magnitudes of vibratory mechanical force application on the KEAP1 molecule and its downstream regulators, such as NRF2 and IKKβ.

Design: A fibroblast cell culture was performed on periodontal ligament cells scraped from atraumatically extracted premolar teeth. These cells were subjected to low (50 Hz), medium, (100 Hz) high (150 Hz), and very high (200 Hz) vibratory settings for 20 min at 0, 24, and 48 h. mRNA and protein analysis of KEAP1, NRF2, and IKKβ was performed using real-time PCR, indirect ELISA test, and Western blot, respectively.

Results: The results indicated that vibratory mechanical force application interfered with cultured periodontal ligament fibroblasts' normal growth and homeostasis. While KEAP1's mRNA expression and protein activity were downregulated, NRF2's and IKKβ's were upregulated. As force magnitude increases, KEAP1's downregulation increases, while NRF2 and IKKβ's upregulation continues.

Conclusions: The study revealed an inverse relationship between KEAP1, NRF2, and IKKβ in periodontal ligament fibroblasts subjected to mechanical forces. A decrease in KEAP1 and an increase in NRF2 and IKKβ mRNA and protein levels to different vibrational frequencies can evoke cytoprotective responses in the cells.

Keywords: Cytoprotection; IKKbeta protein; KEAP1 protein; Periodontal ligament.