Hippo-YAP signaling pathway regulates autophagy of human periodontal ligament cells under cyclic tensile stress.

Objectives: This work aimed to investigate the molecular mechanism of cyclic tensile stress (CTS) stimulating autophagy in human periodontal ligament cells (hPDLCs).

Methods: hPDLCs were isolated and cultured from normal periodontal tissues. hPDLCs were loaded with tensile stress by force four-point bending extender to simulate the autophagy of hPDLCs induced by orthodontic force du-ring orthodontic tooth movement. XMU-MP-1 was used to inhibit the Hippo signaling pathway to explore the role of the Hippo-YAP signaling pathway in activating hPDLC autophagy by tensile stress. The expression levels of autophagy-related genes (Beclin-1, LC3, and p62) in hPDLCs were detected by real-time quantitative polymerase chain reaction. Western blot was used to detect the expression levels of autophagy-related proteins (Beclin-1, LC3-Ⅱ/LC3-Ⅰ, and p62) and Hippo-YAP pathway proteins (active-YAP and p-YAP) in hPDLCs. Immunofluorescence was used to locate autophagy-related proteins (LC3-Ⅱand p62) and Hippo-YAP pathway proteins (active-YAP) of hPDLCs.

Results: CTS-activated autophagy in hPDLCs and expression of autophagy-related proteins initially increased and then decreased; it began to increase at 30 min, peaked at 3 h, and decreased (P<0.05). CTS increased the expression of active-YAP protein and decreased the expression of p-YAP protein (P<0.05). When XMU-MP-1 inhibited the Hippo-YAP signaling pathway (P<0.05), active-YAP protein was promoted to enter the nucleus and autophagy expression was enhanced (P<0.05).

Conclusions: The Hippo-YAP signaling pathway is involved in the regulation of autophagy activation in hPDLCs under CTS.