The Preliminary Study Of The Effect And Mechanism Of Low Shear Stress On Vascular Endothelial Cells Autophagy

[Objective] To explore the effect of low shear stress on vascular endothelial cells(VECs) autophagy. [Methods] 1. apo E-/- mice were fed with high fat diet for 0, 4, 8 or 12 weeks. HE and oil red O staining were used to detect the pathological changes of aortic sinus. Immunohistochemistry and Western blot were applied to detect the protein expression of autophagy associated genes BECLIN 1, microtubule-associated protein 1 light chain 3(LC3), P62 and TET2. Immunofluorescence was applied to observe the content of 5-m C and 5-hm C. 2. Human umbilical vein endothelial cells(HUVECs) were placed in an ex vivo cell perfusion system with low shear stress(5 dyne /cm2) or normal shear stress(15 dyne /cm2) for 1h, Western blot was used to measure the protein expression of BECLIN 1, LC3, P62 and TET2. To explore the effect of low shear stress on VECs autophagy flux, HUVECs were treated with shear stress for 1 h followed with bafilomycin A1 for 2 h. 3. To explore the effect of TET2 on VECs autophagy, HUVECs were transfected with TET2 overexpression or sh RNA plasmid. The levels of BECLIN 1, LC3 and P62 were measured by Western blot. To explore the effect of TET2 on VECs autophagy and function under low shear stress, HUVECs were transfected with TET2 overexpression or sh RNA plasmid, and then treated with shear stress for 1 h. Western blot was used to measure the levels of BECLIN 1, LC3, P62, e NOS and ET-1. [Results] The contents of BECLIN 1, LC3 II and P62 were significantly increased during atherosclerotic lesions progression. However, the levels of TET2 were significantly decreased. The content of 5-m C was increased, and its increasing amplitude was significantly higher than 5-hm C. Compared to 15 dyne/cm2 treatment group, TET2, BECLIN 1 and LC3 contents were significantly decreased companying with P62 expression increased in 5 dyne/cm2 treatment group. After treatment with bafilomycin A1 for 2 h, LC3 content didn’t change obviously in 5 dyne/cm2 treatment group, but was increased in 15 dyne/cm2 treatment group. After treatment with overexpression of TET2, the protein contents of BECLIN 1 and LC3 were significantly increased and P62 expression was decreased. After treatment with overexpression of TET2 followed shear stress, BECLIN 1, LC3 and e NOS protein expression were increased and P62 and ET-1 protein expression were decreased. [Conclusion] Low shear stress inhibites VECs autophagy by decreasing the protein expression of TET2.