Effects of 625 nm light-emitting diode irradiation on preventing ER stress-induced apoptosis via GSK-3β phosphorylation in MC3T3-E1

Prolonged endoplasmic reticulum (ER) stress contributes to cell apoptosis and interferes with bone homeostasis. Although photobiomodulation (PBM) might be used for ER stress-induced diseases, the role of PBM in relieving cell apoptosis remains unknown. During ER stress, glycogen synthase kinase-3 beta (GSK-3 beta) is critical; however, its functions in PBM remain uncertain. Thus, this study aimed to investigate the role of GSK-3 beta in 625 nm light-emitting diode irradiation (LEDI) relieving tunicamycin (TM)-induced apoptosis. Based on the results, pre-625 nm LEDI (Pre-IR) phosphorylated GSK-3 beta via ROS production. Compared with the TM group, Pre-IR + TM group reduced the phosphorylation of the alpha-subunit of eukaryotic translation initiation factor 2 (eIF-2 alpha) and B-cell lymphoma protein 2 (Bcl-2)-associated X (Bax)/Bcl-2 ratio through regulating GSK-3 beta. Furthermore, a similar tendency was observed between Pre-IR + TM and Pre-LiCl+TM groups in preventing TM-induced early and late apoptosis. In summary, this study suggests that the Pre-IR treatment in TM-induced ER stress is beneficial for preventing cell apoptosis via GSK-3 beta phosphorylation.