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

Area of Science:

• Cardiovascular Biology
• Cellular Mechanobiology
• Molecular Signaling

Background:

• Endothelial cells (ECs) respond to blood flow shear stress (SS) via mechanotransduction.
• Extracellular ATP released by SS regulates vascular dynamics.
• Cyclooxygenase-2 (COX-2) in ECs has antithrombotic and vasodilatory roles, but its regulation by SS-induced ATP is unclear.

Purpose of the Study:

• To investigate if extracellular ATP released by SS under disturbed flow promotes COX-2 expression in mouse brain microvascular ECs.
• To elucidate the signaling pathway involved in SS-induced COX-2 regulation.

Main Methods:

• Utilized mouse brain microvascular EC line bEnd.3 subjected to disturbed flow via orbital shaking.
• Measured ATP release and COX-2 expression.
• Administered exogenous ATP, uridine 5'-triphosphate (UTP), and P2Y2 receptor antagonist AR-C118925XX.
• Investigated the Gq/protein kinase C/extracellular signal-regulated kinases 1/2 signaling cascade.

Main Results:

• Disturbed flow-induced SS triggered ATP release and upregulated COX-2 expression in ECs.
• Exogenous ATP and UTP increased COX-2 expression, suppressed by P2Y2 receptor antagonist.
• P2Y2 receptor antagonist attenuated disturbed flow-induced COX-2 expression.
• P2Y2 receptor-mediated COX-2 upregulation depended on Gq/PKC/ERK1/2 signaling.

Conclusions:

• SS-induced ATP release from ECs contributes to maintaining endothelial COX-2 expression.
• P2Y2 receptor signaling is a key component of endothelial mechanotransduction in response to disturbed flow.
• This pathway highlights a mechanism for regulating vascular function under altered flow conditions.