IRE1α inhibits osteogenic differentiation of mouse embryonic fibroblasts by limiting Shh signaling

• Published in: Oral diseases 2024-10, Vol.30 (7), p.4504-4517
• Main Authors: Zhang, Zhixiang, Zhang, Xuan, Wei, Xiangzhen, Yu, Chengbo, Xiao, Li, Liu, Jianmiao, Liu, Yong, Cao, Yingguang, Song, Ke
• Format: Article
• Language: English
• Subjects: Alkaline phosphatase; Alkaline Phosphatase - metabolism; Animals; Ankylosis; Cell Differentiation; Cells, Cultured; Embryo fibroblasts; Endoplasmic reticulum; Endoplasmic Reticulum Stress; Endoribonucleases - genetics; Endoribonucleases - metabolism; ER stress; Fibroblasts; Fibroblasts - metabolism; Hedgehog protein; Hedgehog Proteins - metabolism; Inositol; IRE1α; Mice; Mineralization; mouse embryonic fibroblasts; Ossification; Osteogenesis; Protein folding; Protein Serine-Threonine Kinases - genetics; Protein Serine-Threonine Kinases - metabolism; Signal Transduction; sonic hedgehog; Unfolded Protein Response
• ISSN: 1354-523X; 1601-0825; 1601-0825
• DOI: 10.1111/odi.14919

Objectives This study aimed to investigate the effect of endoplasmic reticulum (ER) stress sensor inositol‐requiring enzyme 1α (IRE1α) on the sonic hedgehog N‐terminus (N‐Shh)‐enhanced‐osteogenic differentiation process in mouse embryonic fibroblasts (MEFs). Materials and Methods Osteogenesis of MEFs was observed by alkaline phosphatase (ALP) staining, alizarin red staining, and Von Kossa staining assays. Activation of unfolded protein response and Shh signaling were examined using real‐time quantitative PCR and western blot assays. IRE1α‐deficient MEFs were used to explore the effect of IRE1α on N‐Shh‐driven osteogenesis. Results N‐Shh increased ALP activity, matrix mineralization, and the expression of Alp and Col‐I in MEFs under osteogenic conditions; notably, this was reversed when combined with the ER stress activator Tm treatment. Interestingly, the administration of N‐Shh decreased the expression of IRE1α. Abrogation of IRE1α increased the expression of Shh pathway factors in osteogenesis‐induced MEFs, contributing to the osteogenic effect of N‐Shh. Moreover, IRE1α‐deficient MEFs exhibited elevated levels of osteogenic markers. Conclusions Our findings suggest that the IRE1α‐mediated unfolded protein response may alleviate the ossification of MEFs by attenuating Shh signaling. Our research has identified a strategy to inhibit excessive ossification, which may have clinical significance in preventing temporomandibular joint bony ankylosis.