P372Early shear stress effects on vascular endothelium by a modified partial carotid ligation model

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Abstract

Introduction

Partial carotid ligation is characterized as the most representative method for studying shear stress effects related to endothelial dysfunction. The molecular events through which mechanical forces trigger this signaling pathway remain elusive. Previous studies have demonstrated that the mechanosensor proteins Polycystin 1 (PC-1) and Polycystin 2 (PC-2) are required for endothelial fluid shear stress responses in vitro.

Methods

We developed a sufficient partial ligation technique with a new and simple modification and explored in vivo the expression/activation of PC-1 and PC-2 in association with p53 status. Flow velocity of Left and Right Common Carotid Artery (LCCA and RCCA, respectively) was determined by high-resolution ultrasonography (Vivid 7, GE). The validity of the technique was further confirmed by investigating the expression profile of eNOS pathway.

Results

Wall shear stress level was significantly reduced in LCCA after ligation (p < 0.05) and decreased further five days later (p < 0.05). Immunohistochemical analysis revealed decreased phospho(p)-eNOS immunoreactivity in the endothelial cells of low shear stress region (5-10%) compared to RCCA (80-100%, p=0.042). Increased PC-1 immunoreactivity was observed in the cytoplasm of endothelial cells of low shear stress region (LCCA, 60%) compared to RCCA (10%, p=0.043). A similar pattern was also obtained for PC-2 (80% vs 10%, p=0.043). Western immunobloting analysis of phospho(p)-p53, a known effector/modulator of polycystin signaling/expression revealed increased levels of activated p53 in the LCCA vs RCCA.

Conclusions

This partial carotid ligation model provides a simple and reliable method to study flow-dependent endothelial dysfunction in vivo. Moreover, our study demonstrates the low shear stress effects on endogenous PC-1 and PC-2 expression pattern in vascular endothelial cells. Finally, our data reveal a similar expression pattern between p53 activation and polycystins' low shear stress responsive changes in vivo.

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