Sprouty2 expression controls endothelial monolayer integrity and quiescence

Area of Science:

• Endothelial biology
• Vascular development
• Cell signaling

Background:

• Vascular integrity relies on quiescent endothelial cells, but mechanisms maintaining quiescence amid angiogenic factors are unclear.
• Endothelial cells form a barrier essential for mature blood vessel formation.

Purpose of the Study:

• To investigate the role of Sprouty2 (Spry2) in mediating endothelial quiescence and barrier integrity.
• To understand how Spry2 influences endothelial cell proliferation and morphology in response to fibroblast growth factor 2 (FGF2).

Main Methods:

• Utilized mouse aortic endothelial cells (MAECs) with and without Sprouty2 (Spry2) knockout.
• Assessed cell morphology, proliferation, and monolayer formation in the presence of FGF2.
• Analyzed Spry2 expression levels in relation to cell density and cell-cell contact.
• Measured extracellular signal-regulated kinase 1/2 (Erk1/2) phosphorylation.

Main Results:

• Spry2 knockout MAECs exhibited spindle-like shapes and failed to form impermeable monolayers.
• Spry2 knockout MAECs proliferated excessively even at high densities, unlike wild-type cells exhibiting contact inhibition.
• Spry2 expression increased with cell density and intact cell-cell contacts, and correlated with decreased Erk1/2 phosphorylation.
• Inhibiting Erk1/2 in Spry2 knockout cells restored normal monolayer morphology.

Conclusions:

• Sprouty2 (Spry2) is a key mediator of endothelial contact inhibition and barrier integrity.
• Spry2's function is cell density-dependent and linked to the regulation of Erk1/2 signaling.
• This study reveals a novel role for Spry2 in maintaining vascular health.