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Updated: Jun 3, 2026

Laser Capture Microdissection of Mouse Embryonic Cartilage and Bone for Gene Expression Analysis
Published on: December 18, 2019
The IRE1α-XBP1 pathway is essential for osteoblast differentiation through promoting transcription of Osterix
Takahide Tohmonda1, Yoshiteru Miyauchi, Rajarshi Ghosh
1Department of Anti-aging Orthopedic Research, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
Abstract:
During skeletal development, osteoblasts produce large amounts of extracellular matrix proteins and must therefore increase their secretory machinery to handle the deposition. The accumulation of unfolded protein in the endoplasmic reticulum induces an adoptive mechanism called the unfolded protein response (UPR). We show that one of the most crucial UPR mediators, inositol-requiring protein 1α (IRE1α), and its target transcription factor X-box binding protein 1 (XBP1), are essential for bone morphogenic protein 2-induced osteoblast differentiation. Furthermore, we identify Osterix (Osx, a transcription factor that is indispensible for bone formation) as a target gene of XBP1. The promoter region of the Osx gene encodes two potential binding motifs for XBP1, and we show that XBP1 binds to these regions. Thus, the IRE1α-XBP1 pathway is involved in osteoblast differentiation through promoting Osx transcription.
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