Disturbed Flow-Induced ATP Release Upregulates COX-2 Expression via P2Y₂ Receptor in bEnd.3 Endothelial Cells

Shear stress (SS) generated by blood flow elicits endothelial cell (EC) responses through mechanotransduction pathways. In particular, ATP released by SS is instrumental in regulating vascular dynamics. Cyclooxygenase-2 (COX-2), typically induced by inflammatory responses, is also constitutively expressed in vascular ECs under SS and exerts antithrombotic and vasodilatory effects. However, the mechanism whereby SS-induced ATP release regulates COX-2 expression remains incompletely understood. In this study, we investigated whether extracellular ATP released by SS under disturbed flow conditions promotes COX-2 expression in the mouse brain microvascular EC line bEnd.3. SS applied by disturbed flow via orbital shaking triggered ATP release and upregulated COX-2 expression. Moreover, stimulation by exogenous ATP and uridine 5'-triphosphate (UTP) increased COX-2 expression, which was suppressed by the P2Y₂ receptor antagonist AR-C118925XX. Disturbed flow-induced COX-2 expression was consistently attenuated by AR-C118925XX. Mechanistically, P2Y₂ receptor-mediated upregulation of COX-2 was dependent on the Gq/protein kinase C/extracellular signal-regulated kinases 1/2 signaling cascade. These findings suggest that SS-induced ATP released from ECs contributes to maintaining the expression of endothelial COX-2, highlighting the role of P2Y₂ receptor signaling in endothelial mechanotransduction.