ABSTRACT
Objective To investigate the gene expression of Piezo1 in four types of bone cells at different stages of osteogenic differentiation under fluid shear stress (FSS). Methods The mouse-derived mesenchymal stem cells (MSC), osteoblast-like cells MC3T3-E1, post-osteoblasts MLO-A5 and osteocytes MLO-Y4 were exposed to FSS at different magnitude (0.1, 1.1 Pa) with a custom-made cone-plate flow chamber for 0.5, 1, 3, 6, 12 h, respectively. The expression of Piezo1 mRNA was assessed by quantitative real-time polymerase chain reaction. Results Both Piezo1 and Piezo2 were expressed in four types of bone cells. The expression of Piezo1 was significantly up-regulated in all cells under FSS stimulation, and the expression level under 1.1 Pa FSS was significantly higher than that under 0.1 Pa FSS. In addition, the expression of Piezo1 in MSC, MC3T3-E1 and MLO-A5 cells increased to the highest level at 1 h under FSS stimulation. The expression of Piezo1 in MC3T3-E1 cells was much higher than that in the other three types of cells. Conclusions The expression of Piezo1 was related to the process of osteogenic differentiation, FSS level and loading time, and this research finding is of great significance to reveal the mechanism of mechanotransduction in bone tissues and to establish clinical treatment for bone diseases.
ABSTRACT
BACKGROUND:Cel co-culture can maximize the simulation ofin vivomicroenvironment. Cel scratch test and interleukin-1β can destroy the balance between matrix metaloproteinases (MMPs) and matrix metaloproteinase inhibitors (TIMPs), resulting in extracelular matrix degradation of the articular cartilage, functional disorders of chondrocytes and articular cartilage degeneration. OBJECTIVE:To study the effect of interleukin-1β on migration, MMP and TIMP expression of chondrocytes co-cultured with osteoblast supernatantin vitro. METHODS:There were three groups: chondrocyte monoculture group, osteoblast+chondrocyte group (co-culture group), osteoblast+chondrocyte+interleukin-1β group (interleukin-1β group). Cel scratch test was conducted to observe the migration of chondrocytes within 24 hours. Semi-quantitative PCR test was used to detect the changes in expressions of MMP-1, MMP-2, MMP-3, MMP-9, TIMP-1, TIMP-2, TIMP-3, TIMP-9 in chondrocytes within 24 hours. RESULTS AND CONCLUSION:Compared with the monoculture group, cel migration rate of the other two groups were increased significantly (P< 0.01). Compared with the monoculture group, the gene expressions of MMP-1, MMP-2, MMP-3 and MMP-9 were increased significantly in the coculture group (P < 0. 05); the gene expressions of MMP-1, MMP-3, MMP-9 were increased significantly in the interleukin-1β group (P< 0. 01). Compared with monoculture group, the gene expression of TIMP-1 was increased significantly (P < 0. 01), but the gene expressions of TIMP-3 and TIMP-4 were declined significantly (P < 0. 05) in the other two groups. These findings indicate that co-culture of chondrocytes with osteoblasts can promote chondrocytes migration, enhance gene expression of chondrocytes MMP-1, MMP-2, MMP-3, MMP-9 and regulate gene expression of TIMPs family. Interleukin-1β inhibitsthe migration of chondrocytes co-cultured with osteoblasts and gene expression of TIMPs family.
ABSTRACT
During the process of pathogens penetrating the plant cell, pathogens often secret some chemicals into plant cells, at the same time, they also produce mechanical signal by physical pressure on the plant cell. Here the pressure is used as the stress signal, to study its effect on phytoalexin accumulation and the induction of plant resistance in cucumber seedling. It is found that stress can induce the resistance in cucumber seedling significantly. When breaking the plant cell wall and plasma membrane adhesion by RGD peptides, the resistance induction is almost eliminated. Results from TLC and HPLC showed that stress stimulation could increase phytoalexin accumulation in cucumber seedling. This suggests that the accumulation of phytoalexin is one possible reason of the increased resistance after stress stimulation. When the adhesion between plant cell wall and plasma membrane was block by RGD, there is only small amount of phytoalexin accumulation compared with the control, suggesting that the stress induced phytoalexin accumulation and resistance is relying on the adhesion of plant cell wall and plasma membrane.