Department of Orthopaedics, the Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Zhejiang, Hangzhou, China.
Guangdong Provincial Key Laboratory of Orthopaedics and Traumatology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
FASEB J. 2024 May 31;38(10):e23646. doi: 10.1096/fj.202302425R.
Multiple regulatory mechanisms are in place to ensure the normal processes of bone metabolism, encompassing both bone formation and absorption. This study has identified chaperone-mediated autophagy (CMA) as a critical regulator that safeguards bone formation from the detrimental effects of excessive inflammation. By silencing LAMP2A or HSCA8, we observed a hindrance in the osteoblast differentiation of human bone marrow mesenchymal stem cells (hBMSCs) in vitro. To further elucidate the role of LAMP2A, we generated LAMP2A gene knockdown and overexpression of mouse BMSCs (mBMSCs) using adenovirus. Our results showed that LAMP2A knockdown led to a decrease in osteogenic-specific proteins, while LAMP2A overexpression favored the osteogenesis of mBMSCs. Notably, active-β-catenin levels were upregulated by LAMP2A overexpression. Furthermore, we found that LAMP2A overexpression effectively protected the osteogenesis of mBMSCs from TNF-α, through the PI3K/AKT/GSK3β/β-catenin pathway. Additionally, LAMP2A overexpression significantly inhibited osteoclast hyperactivity induced by TNF-α. Finally, in a murine bone defect model, we demonstrated that controlled release of LAMP2A overexpression adenovirus by alginate sodium capsule efficiently protected bone healing from inflammation, as confirmed by imaging and histological analyses. Collectively, our findings suggest that enhancing CMA has the potential to safeguard bone formation while mitigating hyperactivity in bone absorption.
多种调节机制被设置来确保正常的骨代谢过程，包括骨形成和吸收。本研究发现伴侣介导的自噬（CMA）是一种关键的调节因子，它可以保护骨形成免受过度炎症的不利影响。通过沉默 LAMP2A 或 HSCA8，我们观察到体外人骨髓间充质干细胞（hBMSCs）的成骨分化受到阻碍。为了进一步阐明 LAMP2A 的作用，我们使用腺病毒生成了 LAMP2A 基因敲低和过表达的小鼠 BMSCs（mBMSCs）。结果表明，LAMP2A 敲低导致成骨特异性蛋白减少，而过表达 LAMP2A 则有利于 mBMSCs 的成骨作用。值得注意的是，LAMP2A 的过表达上调了活性-β-catenin 水平。此外，我们发现 LAMP2A 的过表达通过 PI3K/AKT/GSK3β/β-catenin 通路有效地保护 mBMSCs 的成骨作用免受 TNF-α的影响。此外，LAMP2A 的过表达显著抑制了 TNF-α诱导的破骨细胞过度活跃。最后，在小鼠骨缺损模型中，我们通过藻酸钠胶囊控制释放 LAMP2A 过表达腺病毒，通过成像和组织学分析证实，有效地保护骨愈合免受炎症的影响。总之，我们的研究结果表明，增强 CMA 有可能保护骨形成，同时减轻骨吸收的过度活跃。
