miR-20b-5p inhibits inflammation-induced endoplasmic reticulum stress through EIF2S1 and promotes osteogenic differentiation of bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs) play crucial roles in bone tissue regeneration and repair due to their self-renewal ability and multidifferentiation potential. Additionally, miRNAs play crucial roles in controlling osteogenic differentiation. The purpose of this study was to investigate the impact of miR-20b-5p on the osteogenic differentiation of BMSCs under inflammatory conditions. Human BMSCs were treated with 1 µg/mL lipopolysaccharide (LPS) for 24 h to establish an in vitro inflammatory model simulating inflammation in bone injury. The levels of miR-20b-5p, proteins, and inflammatory cytokines were detected via RT-qPCR, Western blotting, and ELISA, and osteogenic differentiation of the BMSCs was evaluated via ALP and alizarin red staining. Consistent with previous findings, LPS downregulated osteogenic markers (RUNX2, OCN, OPN) and upregulated inflammatory cytokines (TNF-α, IL-6, and IL-1β) in BMSCs. Furthermore, the levels of miR-20b-5p were decreased, and the levels of endoplasmic reticulum stress-related proteins (p-EIF2S1, ATF4, CHOP, and GRP78) were increased in LPS-induced BMSCs. However, overexpression of miR-20b-5p weakened the effect of LPS and promoted osteogenic differentiation. Mechanistically, miR-20b-5p overexpression alleviated ER stress caused by LPS-induced inflammation by decreasing EIF2S1 levels, thereby promoting the osteogenic differentiation of BMSCs. Our research indicates that increasing miR-20b-5p expression could be an innovative approach to promote osteogenic differentiation of BMSCs.