Galectin-9 induces osteoblast differentiation through the CD44/Smad signaling pathway

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• 作者：Rena Tanikawa ; Takahisa Tanikawa ; Mitsuomi Hirashima ; Akira Yamauchi ; Yoshiya Tanaka
• 关键词：Galectin-9 ; Osteoblast ; CD44 ; Smad
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2010
• 出版时间：2 April 2010
• 年：2010
• 卷：394
• 期：2
• 页码：317-322
• 全文大小：1173 K

文摘

Galectin-9 is a β-galactoside-binding lectin expressed in various tissues. It binds various glycoconjugates and modulates a variety of biological functions in various cell types. Although galectin-9 is expressed in bone, its function in human osteoblasts remains unclear. We demonstrate that galectin-9 induces osteoblast differentiation through the CD44/Smad signaling pathway in the absence of bone morphogenetic proteins (BMPs). Galectin-9 increases alkaline phosphatase activities in human osteoblasts and induces the phosphorylation of Smad1/5/8 and translocation of Smad4 to the nucleus in the absence of BMPs. Galectin-9 also induces binding of Smad4 to the Id1 promoter and increases its activity. Anti-CD44 antibody inhibits Smad1/5/8 phosphorylation by galectin-9. Galectin-9 binds to CD44 and induces the formation of a CD44/BMP receptor complex. Because Smad1 is phosphorylated by BMP receptors, we propose that formation of the CD44/BMP receptor complex induced by galectin-9 may provide a trigger for the activation of Smads.