切应力对内皮细胞组织因子表达上调的影响及其作用机制

The Effect and Its Mechanism of the Fluid Shear Stress on Expression of Tissue Factor in Endothelial Cells

研究切应力对内皮细胞组织因子表达的影响及其作用机制。利用原位杂交和免疫组织化学观察组织因子基因、Sp1和Egr 1的mRNA转录及蛋白表达。切应力作用采用平行板流动腔系统给予。结果发现 ,在静置培养内皮细胞中 ,组织因子基因mRNA及蛋白表达极低 ,促凝活性也低。Sp1蛋白表达在胞核较高 ,Sp1mRNA表达在胞浆较高。Egr 1在胞核和胞浆均无表达或表达极低。在切应力 (1.2、2 .4及 4 .8Pa)作用后 ,内皮细胞胞浆组织因子基因mRNA转录和蛋白合成及组织因子促凝活性升高 ,与对照组比较均有显著性差异 (P <0 .0 5 )。Sp1和Egr 1基因mRNA转录和蛋白合成均有增加 (P <0 .0 5 ) ,但以Egr 1增加更显著 (P <0 .0 5 ) ,其变化趋势与组织因子基因mRNA转录、组织因子基因蛋白合成、组织因子促凝活性的变化趋势相同。结果提示 ,切应力是内皮细胞组织因子基因表达上调的触发因素之一 ,其触发机制与转录因子Egr 1和Sp1介导有关。

Aim to investigate the effect of fluid shear stress on tissue factor (TF) high expression in endothelial cells and discuss its possible mechanism. Methods mRNA expression of TF, transcription factors nuclear factor Sp1 and Egr-1 and their relative antigen were analyzed by in sito hybridization and immunohistochemistry staining, respectviely. Functional TF activity was assessed by one-step recalcification clotting time assay, meanwhile, a simple parallel flow chamber system, which can produce 0～4.8 Pa steady laminar flow shear stress, was established in order to study the effect of blood flow shear stress on endothelial cells (EC). Results In hUVEC, TF functional activity, antigen and mRNA are very low; Sp1 protein expression increased in karyon, but the transcriptional activity of Sp1 is high in cytoplasm; Egr-1 mRNA and protein expresion is absent or fewer in karyon and cytoplasm. After 6 h exposed to 1.2, 2.4, 4.8 Pa shear stress, mRNA, protein expresion, the procoagulant activity of TF markedly increased comparing with control group (P<0.05). The mRNA and protein expresion of Egr-1 and Sp1 increased (P<0.05). However, the change of Egr-1 was more significant than that of Sp1 (P<0.05). The change trend of Egr-1 and Sp1 expresion were similar to that of TF. Conclusion The shear is one of a starting regulator of TF expression in endothelium. Their effect is mediated by transcription factors nuclear factor Egr-1 and Sp1.