Role of an auxilliary subunit of voltage-gated Na+ channels in endothelial functions: Is Navβ3, a novel actor of vascular mechanosignaling?

Abstract

The endothelial cell (EC) is a central actor to maintain vascular tone and homeostasis. Endothelial dysfunction is responsible for the development of many cardiovascular diseases including atherosclerosis. The endothelial function is mainly stimulated by the shear stress generated by blood flow. The physical forces produced by flow are detected by many mechanosensors in EC, which trigger intracellular signaling pathways influencing endothelial physiology. Among these mechanosensors, several ion channels have been identified. Voltage-gated Na+ (Nav) channels have been shown to be mechanosensitive in cardiac and intestinal cells. These ion channels are also expressed in EC and then we aim to investigate their role in EC responses to shear stress. Confluent Human Umbilical Vein EC (HUVEC) and Human Aorta EC (teloHAEC) were exposed to laminar (LSS, 20 dynes/cm 2 ) or oscillatory shear stress (OSS, 20 dynes/cm 2 , 0.5 Hz frequency) using the Ibidi® pump system. Cell orientation was quantified by local gradient orientation method with Fiji software. RTqPCR and western blot were used to characterize Nav channel subunits at both transcriptional and protein levels. Exposition of HUVEC and TeloHAEC to a LSS for 24 hours and 4 days induced cell orientation in the direction of flow and activated the atheroprotective signaling pathway (KLF2/KLF4, eNOS). Interestingly, shear stress deep changes in several Nav channels subunits expression level. Notably, SCN3B expression, encoding the Ig-CAM Navβ3 protein, was increased with a 2.1 fold increase at 24 hours, 3.9 at 4 days and 12.6 at 7 days in HUVEC and 2.9 at 4 days in teloHAEC. Moreover, trans-resveratrol-induced KLF2 expression led to increase SCN3B expression, suggesting that this atheroprotective transcription factor might be involved in SCN3B regulation. Indeed, OSS, corresponding to an atherogenic flow, did not induce HUVEC alignment in the direction of flow neither activation of atheroprotective signaling pathway nor a significant increase of SCN3B expression. Taken together, our results suggest that Navβ3 could be a putative novel actor in the mechanotransduction of flow and thus in vasculoprotection.