A Thromboxane A₂ Receptor-Driven COX-2-Dependent Feedback Loop That Affects Endothelial Homeostasis and Angiogenesis

Area of Science:

• Vascular Biology
• Endothelial Cell Biology
• Cardiovascular Research

Background:

• Thromboxane A2 receptor (TP) is implicated in endothelial dysfunction and cardiovascular disease.
• TP expression increases in blood vessels of high-risk individuals, but its direct impact on endothelial homeostasis is unknown.

Purpose of the Study:

• To investigate the effects of endothelial TP overexpression or knockdown/knockout on endothelial cell angiogenic capacity.
• To elucidate the molecular mechanisms linking TP signaling to endothelial function.

Main Methods:

• Global transcriptome analysis
• Lipid mediator profiling
• Functional cell assays
• In vivo angiogenesis assays
• Endothelial TP overexpression, knockdown, and knockout models

Main Results:

• Endothelial TP expression induces COX-2 via G(i/o) and G(q/11) signaling, creating an auto/paracrine TP agonist feedback loop.
• TP overexpression leads to endothelial cell tension, aberrant morphology, altered focal adhesion dynamics, and inhibited angiogenesis in vitro and in vivo.
• TP knockdown or knockout reverses these effects.

Conclusions:

• A TP-driven COX-2-dependent feedback loop links TP upregulation to angiostatic signaling in endothelial cells.
• Pathological TP upregulation can directly cause endothelial dysfunction, microvascular rarefaction, and hypertension.
• Targeting this feedback loop offers a novel therapeutic strategy for cardiovascular diseases.