Next Generation Sequencing to analyse regulators of constitutive VWF secretion

Constitutive VWF secretion can be increased by a range of factors; changes in VWF expression, levels of TNF-alpha or other environmental cues. An RNAseq analysis revealed that expression of RGS4 (Regulator of G protein signalling 4) was reduced in endothelial cells (HUVECs) grown under these conditions. si-RGS4 treatment of HUVECs increased constitutive basolateral secretion of VWF, probably by affecting the anterograde secretory pathway. In a simple model of endothelial damage we show that RGS4-silenced cells increased platelet recruitment onto the subendothelial matrix under flow. These results show that changes in RGS4 expression alter levels of subendothelial VWF, affecting platelet recruitment. This introduces a novel control over VWF function. mRNA profiles of conditions (si-VWF, EBM2 medium, TNFalpha and their controls) known to increase VWF constitutive secretion in HUVECs