The 5-hydroxytryptamine type 4 receptor (5-HT4R) regulates many physiological processes, including learning and memory, cognition, and gastrointestinal motility. Little is known about its role in angiogenesis. Using mouse hindlimb ischemia model of angiogenesis, we observed a significant reduction of limb blood flow recovery 14 days after ischemia and a decrease in density of CD31-positive vessels in adductor muscles in 5-HT4R -/- mice compared to wild type littermates. Our in vitro data indicated that 5-HT4R endogenously expressed in endothelial cells (ECs) may promote angiogenesis. Inhibition of the receptor with 5-HT 4R antagonist RS 39604 reduced EC capillary tube formation in the reconstituted basement membrane. Using Boyden chamber migration assay and wound healing "scratch" assay, we demonstrated that RS 39604 treatment significantly suppressed EC migration. Transendothelial resistance measurement and immunofluorescence analysis showed that a 5-HT4R agonist RS 67333 led to an increase in endothelial permeability, actin stress fiber and interendothelial gap formation. Importantly, we provided the evidence that 5-HT4R-regulated EC migration may be mediated by Gα13 and RhoA. Our results suggest a prominent role of 5-HT4R in promoting angiogenesis and identify 5-HT4R as a potential therapeutic target for modulating angiogenesis under pathological conditions.
- 5-hydroxytriptamine 4 receptor
- Endothelial cell migration
- Hindlimb ischemia model