Negative Functional Interaction of Retinoic Acid and TGF-beta Signaling Mediated by TG-interacting Factor During Chondrogenesis

作者：Zhang Hang; Li Ning; Tang Yunan; Wu Weidong; Zhang Qi; Yu Zengli^*

来源：Cellular Physiology and Biochemistry, 2009, 23(1-3): 157-164.

DOI：10.1159/000204104

• RAR
• TGF-beta
• Chondrogenesis
• All-trans retinoic acid (atRA)
• Palatal mesenchyme
• TGIF

We previously showed that atRA (all-trans Retinoic Acid, atRA) inhibites chondrogenesis by downregulation of TGF-beta/Smad signaling. However, the molecular link between RA and TGF-beta signaling is unknown. Using a mouse embryo palate mesenchyme micomass cultures (MMCs) system, we explored interactions of RA and TGF-beta signaling during chondrogenesis. We found that atRA suppressed chondrogenesis and Smad2/3 phosphorylation regardless of the presence of TGF-beta 3. Functional assays indicated that TGF-beta 3 treatment or co-transfection of expressing Smad2/3 vectors suppressed atRA-induced RARE-tk-Luc activity. Conversely, atRA or RAR-overexpression repressed TGF-beta 3-induced transactivation of the TGF-beta-responsive reporter, p3TP-Lux. ChIP assay revealed the binding of the Smad transcriptional corepressor TGIF (TG-interacting factor, TGIF) to RAR beta promoter in control MMCs, but this association was decreased by the addition of RA and increased by TGF-beta 3, respectively. Further examinations revealed that TGIF exerted a pivotal role in regulating crosstalk of RA and TGF-beta signaling, since siRNA knockdown of TGIF partially abolished the ability of atRA to suppress TGF-beta 3-induced chondrogenesis, whereas forced expression of TGIF blocked the ability of TGF-beta 3 to relieve atRA-mediated the suppression of chondrogenesis. Furthermore, we demonstrated that the effects of atRA on TGF-beta-dependent gene activation and of TGF-beta on RA-dependent gene activation are mediated by TGIF with siRNA to downregulate TGIF. Collectively, these findings indicated a negative functional interplay of RA and TGF-beta signaling mediated by TGIF to modulate chondrogenesis in MMCs.

• 出版日期2009
• 单位郑州大学