Liu Xuhui, Zhang Xiaoliu, Luo Zong-Ping
Sport Medicine Research Center, Department of Orthopedic Surgery, Baylor College of Medicine, Houston, TX 77030, USA.
Cell Tissue Res. 2005 Nov;322(2):331-4. doi: 10.1007/s00441-005-0029-8. Epub 2005 Nov 3.
The gene expression of cells in the musculoskeletal system, such as in bone, cartilage, ligament and tendon, is profoundly affected by mechanical loading. Previous studies have demonstrated that the expression of many genes, including collagen types I and III, are affected by mechanical strain in diverse cell types, such as human osteoblast-like SaOs-2 cells. However, whether the effect of mechanical loading on collagen gene expression is strain-related remains unclear. The goal of this study was to determine the relationship between mechanical strain and the gene expression of collagen types I and III in SaOs-2 cells. A Flexercell cellular mechanical loading system was used to subject SaOs-2 cells to equibiaxial cyclic tensile stress at a rate of 0.5 Hz with various strains of 5%, 7.5%, 10%, and 12.5% for 24 h. The relative amount of mRNA of both collagen I and collagen III increased at 5% strain compared with that of the control. As the strain increased, the relative amount of mRNA of collagen I remained stable at strain levels up to 12.5%. However, the mRNA for collagen III began to drop when the strain was greater than 5%, until a 10% strain was reached. From the application of a 10% strain through the maximum loading of a 12.5% strain, the relative amount of collagen III mRNA remained stable at amounts lower than that of the control. Thus, the gene expression of collagen types I and III responds differentially to mechanical strain at various magnitudes.
肌肉骨骼系统中的细胞，如骨骼、软骨、韧带和肌腱中的细胞，其基因表达会受到机械负荷的深刻影响。先前的研究表明，包括I型和III型胶原蛋白在内的许多基因的表达，在多种细胞类型中，如人成骨样SaOs-2细胞，会受到机械应变的影响。然而，机械负荷对胶原蛋白基因表达的影响是否与应变相关仍不清楚。本研究的目的是确定机械应变与SaOs-2细胞中I型和III型胶原蛋白基因表达之间的关系。使用Flexercell细胞机械加载系统，以0.5 Hz的频率对SaOs-2细胞施加等双轴循环拉伸应力，应变分别为5%、7.5%、10%和12.5%，持续24小时。与对照组相比，在5%应变时，I型胶原蛋白和III型胶原蛋白的mRNA相对量均增加。随着应变增加，在高达12.5%的应变水平下，I型胶原蛋白的mRNA相对量保持稳定。然而，当应变大于5%时，III型胶原蛋白的mRNA开始下降，直到达到10%应变。从施加10%应变到最大加载12.5%应变，III型胶原蛋白mRNA的相对量保持稳定，但低于对照组。因此，I型和III型胶原蛋白的基因表达对不同程度的机械应变有不同的反应。
