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Abstract：
Cartilage defects may lead to severe degenerative joint diseases. Tissue engineering based on type I collagen hydrogel that has chondrogenic potential is ideal for cartilage repair. However, the underlying mechanisms of chondrogenic differentiation driven by type I collagen hydrogel have not been fully clarified. Herein, we explored potential collagen receptors and chondrogenic signaling pathways through bioinformatical analysis to investigate the mechanism of collagen-induced chondrogenesis. Results showed that the super enhancer-related genes induced by collagen hydrogel were significantly enriched in the TGF-β signaling pathway, and integrin-β1 (ITGB1), a receptor of collagen, was highly expressed in bone marrow mesenchymal stem cells (BMSCs). Further analysis showed genes such as COL2A1 and Tenascin C (TNC) that interacted with ITGB1 were significantly enriched in extracellular matrix (ECM) structural constituents in the chondrogenic induction group. Knockdown of ITGB1 led to the downregulation of cartilage-specific genes (SOX9, ACAN, COL2A1), SMAD2 and TNC, as well as the downregulation of phosphorylation of SMAD2/3. Knockdown of TNC also resulted in the decrease of cartilage markers, ITGB1 and the SMAD2/3 phosphorylation but overexpression of TNC showed the opposite trend. Finally, in vitro and in vivo experiments confirmed the involvement of ITGB1 and TNC in collagen-mediated chondrogenic differentiation and cartilage regeneration. In summary, we demonstrated that ITGB1 was a crucial receptor for chondrogenic differentiation of BMSCs induced by collagen hydrogel. It can activate TGF-SMAD2/3 signaling, followed by impacting TNC expression, which in turn promotes the interaction of ITGB1 and TGF-SMAD2/3 signaling to enhance chondrogenesis. These may provide concernful support for cartilage tissue engineering and biomaterials development.
摘要：
软骨缺损可导致严重的退行性关节疾病。基于具有软骨形成潜力的I型胶原水凝胶的组织工程是软骨修复的理想选择。然而,由I型胶原水凝胶驱动的软骨分化的潜在机制尚未完全阐明。在这里，我们通过生物信息学分析探索潜在的胶原受体和软骨形成信号通路，以探讨胶原诱导软骨形成的机制。结果表明,胶原水凝胶诱导的超增强子相关基因显著富集在TGF-β信号通路,和整合素-β1（ITGB1），胶原蛋白的受体，在骨髓间充质干细胞（BMSCs）中高表达。进一步分析显示，与ITGB1相互作用的COL2A1和TenascinC（TNC）等基因在软骨形成诱导组中显着富集了细胞外基质（ECM）结构成分。敲除ITGB1导致软骨特异性基因下调（SOX9，ACAN，COL2A1),SMAD2和TNC，以及SMAD2/3磷酸化的下调。敲除TNC也导致软骨标志物的减少，ITGB1与SMAD2/3磷酸化但过表达TNC的趋向相反。最后,体外和体内实验证实了ITGB1和TNC参与胶原蛋白介导的软骨分化和软骨再生。总之,我们证明了ITGB1是胶原水凝胶诱导的BMSCs软骨分化的关键受体。它可以激活TGF-SMAD2/3信号，然后影响TNC表达，进而促进ITGB1和TGF-SMAD2/3信号的相互作用以增强软骨形成。这些可能为软骨组织工程和生物材料的开发提供了令人担忧的支持。
