Effect of endoplasmic reticulum stress on the osteogenic differentiation of periodontal ligament cells under continuous static pressure

To study the effect of continuous static pressure on the endoplasmic reticulum of human periodontal ligament cells (hPDLCs) and the mechanism of osteogenic differentiation.

hPDLCs cultured in vitro were subjected to 1 g/cm² of continuous compressive pressure (CCP) by custom-made, round, glass panes for 0, 2, 4, and 6 h, respectively. Alkaline phosphatase staining was used to detect osteogenic differentiation, and real-time quantitative PCR was used to detect the expression of protein kinase receptor-like ER kinase (PERK), eukaryotic translation initiation factor 2α (eIF2α), and transcription activation factor 4 (ATF-4). The 0 h loading group was the control group.

After CCP treatment, the alkaline phosphatase staining of hPDLCs was blue-violet and significantly stronger than that of cells in the control group. The expression levels of PERK and ATF4 in the hPDLCs after CCP treatment were higher than those of cells in the control group (P < 0.05) and increased over time (P < 0.05). The expression of eIF2α was lower in the experimental groups than in the control group (P < 0.05) and decreased over time (P < 0.05).

Mechanical stimulation can activate ERS in hPDLCs, leading to enhanced PERK-eIF2α-ATF4 signaling and inducing osteogenic differentiation.