635nm LED irradiation may prevent endoplasmic reticulum stress in MC3T3-E1 cells.

Abstract

Although endoplasmic reticulum (ER) stress is thought to be involved in various diseases such as cancer, metabolic, and inflammatory disorders, the relationship between ER stress and bone diseases, are remains unclear. Tunicamycin-treated MC3T3-E1 osteoblasts were used as the ER stress model in this study. 635nm light-emitting diode irradiation (635nm-IR) was carried out for 1h before and after inducing ER stress. To investigate the effects of 635nm-IR on ER stress-induced MC3T3-E1 osteoblasts and the underlying mechanism, western blot, reverse transcription polymerase chain reaction, alkaline phosphatase and Alizarin red staining, 2',7'-dichlorodyhydrofluorescein diacetate assay, Fluo-3AM and immunocytochemistry were performed. Pretreatment with 635nm-IR effectively prevented intracellular reactive oxygen species production and alleviated ER stress through the pancreatic ER kinase (PERK)-eukaryotic initiation factor 2 (eIF2)-activating transcription factor 4 (ATF4)-nuclear factor-like 2 (Nrf2) signaling pathway. Hence, 635nm-IR may serve a protective role in the treatment of ER stress-related bone diseases.