A study for role of small GTPases in mechanical stress response of chondocytes

软骨是对机械刺激做出反应的主要骨骼元件之一，其不仅支持颞下颌关节功能，而且支持身体、气管、耳朵和鼻中隔中的关节。所有这些软骨在骨骼的生长以及抵抗身体中的机械负荷中起着重要作用。阐明软骨细胞的分化机制以及软骨细胞如何产生其特异性大分子并降解它们，对于阐明面部生长和关节疾病的发生发展机制至关重要。特别是阐明软骨细胞增殖、分化和代谢的调控机制和调控因子，对软骨细胞学的发展具有重要意义。在我们以前的研究中，我们发现共享应力和/或张应力抑制胚胎干细胞来源的软骨细胞的分化和次级软骨如下颌髁状软骨和软骨细胞的成熟。 ...更多信息 d腭中缝软骨。同时，张应力也诱导软骨细胞的去分化。相反，压力促进软骨细胞的分化。本研究从细胞外信号调节激酶（extracellular signal regulated kinase，ERK）-1/2的磷酸化和小G蛋白Rho的激活两个方面，验证了细胞内酪氨酸激酶途径在软骨细胞机械应力反应中的作用。本研究采用大鼠胚胎肢芽间充质细胞。采用Flexcer细胞培养板的微团培养系统和机械应力加载系统，定量分析ERK-1/2和Rho的激活和基因表达。力负荷后（30 min内），Rho立即被激活，60 min时达到高峰，基因表达上调。同时，在不刺激ERK-1/2基因表达的情况下，压力负荷60 min后ERK-1/2被磷酸化，这种机械刺激导致软骨形成受到抑制。因此，这些分子在分化软骨细胞的机械应力中起关键作用。少

Cartilage is one of the major skeletal elements responding to mechanical stimulations that support not only temporomandibular joint function but also joints in the body, trachea, ear and nasal septurn. All these cartilages play major roles in the growth of skeletons as well as resisting to mechanical loading in the body. It is extremely important to clarify the mechanisms how chondrocytes differentiate and how chondrocytes produce their specific macromolecules and degrade them to clarify the mechanisms of facial growth and development of joint diseases. Especially, verifying the mechanisms and factors that regulates chondrocyte proliferation, differentiation and metabolismis critical for the development of the field of orthodontics. In our previous studies, we discovered that the sharing stress and/or tensile stress inhibited differentiation of chondrocytes derived from embryonic stem cells and maturation of chondrocytes in secondary cartilages such as mandibular condylar cartilages an … More d midpalatal suture cartilages. At the same time, tensile stress induced de-differentiation of chondrocytes as well. Contrary, compressive force enhanced the differentiation of chondrocytes. These revealed that the quantitative and qualitative difference of mechanical stress loaded on chondrocytes induces different responses of chondrogenic mesenchymal cells.In the present study, we verified the role of itnracellular tyrosine kinase pathway in mechanical stress response of chondrocytes focusing on the phospholyration of extracellular signal-regulated kinase (ERK)-1/2 and activation of small GTPase, Rho. Mesenchymal cells derived from embryonic rat limb bud was used for the present study. By using micromass culture system and mechanical stress loading system utilizing Flexcer Cell plate, activation and gene expression of ERK-1/2 and Rho was quatitated. Immediately after force loading (in 30 min), Rho was activated and peaked at 60min with up-regulation of gene expression. At the same time, ERK-1/2 was phospholyrated in 60 min after force loading while gene expression was not stimulated This mechanical stimulation resulted in the inhibition of chondrogenesis. Thus, these molecules play pivotal roles in the mechanical stress of differentiating chondrocytes. Less