| As one of the most main cells in vascular wall, endothelial cells (ECs) structure and functional integrity are important in homeostasis of the vessel wall. Previous studies has suggested that vascular endothelial structure and function disorder will cause a series cascade reaction, which play crucial roles in the development of cardiovascular disease,such as atherosclerosis,coronary heart disease,myocardial infarction and stroke. Hemodynamics play vital role of in vascular remodeling as well as modulate the differentiation, migration, proliferation, and apoptosis of vascular cells. ECs are permanently exposed to the blood flow shear stress and cyclic tensile strain for pulsatile blood flow in vivo. The sduty on the effect and mechanism of cyclic strain on ECs proliferation will contribute a lot to illustrate the mechanobiological mechanism in vascular remodeling.The cultured human umbilical vein endothelial cells(HUVECs) were subjected to 10%-1.25Hz-cyclic strain using FX-4000T Flexercell system for 12 h,24 h,48 h and 72 h respectively. HUVECs without strain were used as a static control. HUVEC proliferation was examined with CCK-8 methods. The expression of various related proteins in HUVECs was examined by Western blotting. The inhibitor or RNA interference were applied to activate or block the expression and activity of possible message molecules including SIRT6,IGF-1,p-NFκB and p-Akt in order to investage the regulatory role and mechanism of SIRT6,IGF-1,p-NFκB and p-Akt in the HUVEC proliferation induced by physiological cyclic strain.The results are as follows:①The proliferation of HUVECs was hanced by 10%-1.25Hz-cyclic strain for 12 h or 24 h.②the expression of SIRT6 was decreased by 24 h cyclic strain, whereas IGF-1,p-NFκB and p-Akt protein levels were up-regulated.③SIRT6 RNA interference promoted HUVEC proliferation as well as upregulated p-Akt levels,however,the expression of IGF-1 and p-NFκB was not affected.④IGF-1 induced HUVEC proliferation as well as increased the expression of p-NFκB and p-Akt, but there was not a marked change with SIRT6 protein levels.⑤IGF-1 RNA interference decreased HUVEC proliferation, the expression of p-NFκB and p-Akt, but SIRT6 levels were no significant differences.⑥When the expression of p-NFκB in HUVECs was inhibited by Bay 11-7082, SIRT6 and p-Akt levels were downregulated,but the expression of IGF-1 had no notable variation. Wortmannin inhibited p-AKt expression,but there was no effect on the expression of SIRT6,IGF-1 and p-NFκB.Our data indicate that physiological cyclic strain promotes the proliferation of HUVECs, which may be mediated by up-regulating the secretion of IGF-1 in HUVECs. The down-regulation of the expression of SIRT6 activates PI3K/Akt signaling pathways to modulate HUVEC proliferation. |
