Advanced Glycation End Product 3 (AGE3) Increases Apoptosis and the Expression of Sclerostin by Stimulating TGF-beta Expression and Secretion in Osteocyte-Like MLO-Y4-A2 Cells

作者：Notsu Masakazu; Kanazawa Ippei^*; Takeno Ayumu; Yokomoto Umakoshi Maki; Tanaka Ken ichiro; Yamaguchi Toru; Sugimoto Toshitsugu

来源：Calcified Tissue International, 2017, 100(4): 402-411.

DOI：10.1007/s00223-017-0243-x

• Advanced Glycation End Products
• TGF-beta
• Osteocyte
• Bone quality
• Diabetes mellitus

Advanced glycation end products (AGEs) cause bone fragility due to deterioration in bone quality. We previously reported that AGE3 induced apoptosis and inhibited differentiation via increased transforming growth factor (TGF)-beta signaling in osteoblastic cells. Additionally, we demonstrated that AGE3 increased apoptosis and sclerostin expression and decreased receptor activator of nuclear factor-kappa B ligand (RANKL) expression in osteocyte-like cells. However, it remains unclear whether TGF-beta signaling is involved in the effects of AGEs on apoptosis and the expression of sclerostin and RANKL in osteocytes. Effects of AGE3 on apoptosis of mouse osteocyte-like MLO-Y4-A2 cells were examined by DNA fragmentation ELISA. Expression of TGF-beta, sclerostin, and RANKL was evaluated using real-time PCR, Western blotting, and ELISA kits. To block TGF-beta signaling, we used SD208, a TGF-beta type I receptor kinase inhibitor. AGE3 (200 A mu g/mL) significantly increased apoptosis and mRNA expression of Sost, the gene encoding sclerostin, and decreased Rankl mRNA expression in MLO-Y4-A2 cells. AGE3 significantly increased the expression of TGF-beta. Co-incubation of SD208 with AGE3 significantly rescued AGE3-induced apoptosis in a dose-dependent manner. Moreover, SD208 restored AGE3-increased mRNA and protein expression of sclerostin. In contrast, SD208 did not affect AGE3-decreased mRNA and protein expression of RANKL. These findings suggest that AGE3 increases apoptosis and sclerostin expression through increasing TGF-beta expression in osteocytes, and that AGE3 decreases RANKL expression independent of TGF-beta signaling.

• 出版日期2017-4