This study aimed to elucidate the molecular mechanisms, whereby hyaluronic acid, a main extracellular matrix component of articular cartilage, promotes the chondrogenic differentiation of human amniotic mesenchymal stem cells (hAMSCs). Our previous findings indicated that hyaluronic acid combined with hAMSCs showed a marked therapeutic effect against rat osteoarthritis. In the present study, hyaluronic acid markedly enhanced the expression of chondrocyte-specific markers including Col2α1, Acan, and Sox9 in hAMSCs, with strong synergistic effects on chondrogenic differentiation, in combination with the commonly used inducer, transforming growth factor β3 (TGF-β3). Microarray analysis showed that Ras-like protein family member 11B (RASL11B) played a pivotal role in the process of hyaluronic acid-mediated chondrogenesis of hAMSCs. This directional differentiation was significantly inhibited by RASL11B knockdown, but RASL11B overexpression dramatically promoted the expression of Sox9, a master chondrogenesis transcriptional factor, at the levels of transcription and translation. Increased Sox9 expression subsequently resulted in high expression levels of Col2α1 and Acan and the accumulation of cartilage-specific matrix components, such as type 2 collagen and glycosaminoglycans. Moreover, we observed that RASL11B activated the signal molecules such as ERK1/2, and Smad2/3 in the presence of hyaluronic acid during TGF-β3-induced chondrogenesis of hAMSCs. Taken together, these findings suggest that hyaluronic acid activates the RASL11B gene to potentiate the chondrogenic differentiation of hAMSCs via the activation of Sox9 and ERK/Smad signaling, thus providing a new strategy for cartilage defect repairing by hyaluronic acid-based stem cell therapy.

Impact statement

RASL11B, a member of the small GTPase superfamily, has high similarity to RAS proteins, and involves some pathophysiological processes, such as inflammation, arteriosclerosis, and cancer. However, there is no available information regarding the role of RASL11B in chondrogenic differentiation. We show that RASL11B is activated in the process of HA-mediated chondrogenesis of hAMSCs, and RASL11B regulates the differentiation of hAMSCs into chondrocytes through the activation of Sox9 and ERK/Smad signals. The results of this study support that RASL11B may be used as a target in the chondroinductive differentiation of hAMSCs in the presence of HA and even in the cartilage defect repairing by HA-based stem cell therapy.

中文翻译：

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RASL11B 基因通过激活 Sox9/ERK/smad 信号增强人羊膜间充质干细胞中透明质酸介导的软骨形成分化。

本研究旨在阐明分子机制，即关节软骨的主要细胞外基质成分透明质酸促进人羊膜间充质干细胞 (hAMSCs) 的软骨分化。我们之前的研究结果表明，透明质酸联合 hAMSCs 对大鼠骨关节炎显示出显着的治疗效果。在本研究中，透明质酸显着增强了软骨细胞特异性标志物的表达，包括Col2α1、Acan, 和 hAMSCs 中的 Sox9, 与常用的诱导剂, 转化生长因子 β3 (TGF-β3) 结合, 对软骨分化有很强的协同作用。微阵列分析表明，Ras 样蛋白家族成员 11B (RASL11B) 在透明质酸介导的 hAMSCs 软骨形成过程中起关键作用。这种定向分化受到RASL11B敲低的显着抑制，但RASL11B过表达在转录和翻译水平上显着促进了 Sox9（一种主要的软骨形成转录因子）的表达。Sox9 表达的增加随后导致Col2α1和Acan 的高表达水平以及软骨特异性基质成分的积累，例如 2 型胶原蛋白和糖胺聚糖。此外，我们观察到RASL11B在 TGF-β3 诱导的 hAMSCs 软骨形成过程中，在透明质酸存在下激活信号分子，如 ERK1/2 和 Smad2/3。综上所述，这些发现表明透明质酸通过激活 Sox9 和 ERK/Smad 信号传导激活RASL11B基因以增强hAMSCs的软骨形成分化，从而为通过基于透明质酸的干细胞疗法修复软骨缺损提供了新策略。

影响陈述

RASL11B是 GTPase 小超家族的成员，与 RAS 蛋白具有高度相似性，并涉及炎症、动脉硬化和癌症等一些病理生理过程。然而，没有关于RASL11B在软骨分化中的作用的可用信息。我们表明，RASL11B在hAMSCs的HA介导的软骨的方法活化，并RASL11B通过Sox9的和ERK / Smad蛋白信号的激活调节hAMSCs分化成软骨细胞。这项研究的结果支持RASL11B可以用作在 HA 存在下 hAMSCs 的软骨诱导分化中的靶标，甚至可以用作基于 HA 的干细胞疗法修复软骨缺损的靶标。