A paeonol derivative, YPH-PA3 promotes the differentiation of monocyte/macrophage lineage precursor cells into osteoblasts and enhances their autophagy.

Previous studies have indicated that paeonol inhibits RANKL-induced osteoclastogenesis by inhibiting the ERK, p38, and NF-κB pathway. We modified paeonol to form a new compound, YPH-PA3, and found that it promoted osteoclastogenesis rather than inhibited it the way paeonol does. The aim of this study is to investigate the mechanisms involved in YPH-PA3-promoted osteoclastogenesis. YPH-PA3-promoted differentiation of RAW264.7 cells (human monocytes) into osteoclasts is activated through ERK/p38/JNK phosphorylation, affecting c-FOS, NF-κB, and NFATc2. Real-time quantitative PCR and western blot revealed an increased expression of autophagy-related markers during YPH-PA3-induced osteoclastogenesis. We also demonstrated the relationship between p62/LC3 localization and F-actin ring formation by double-labeling immunofluorescence. Knockdown of p62 small-interfering RNA (siRNA) attenuated YPH-PA3-induced expression of autophagy-related genes. Our study results indicated that p62 may play a role in YPH-PA3-induced autophagy and osteoclastogenesis, which may help to develop a novel therapeutic strategy against osteoclastogenesis-related diseases.