Transglutaminase 1 stabilizes beta-actin in endothelial cells correlating with a stabilization of intercellular junctions.

Microvascular endothelial monolayers from mouse myocardium become resistant to various barrier-compromising stimuli correlating with the expression of transglutaminase 1 (TGase1) and its translocation towards cellular junctions. In contrast, endothelial monolayers from mouse lung microvessels do not express TGase1 and remain sensitive to barrier-compromising stimuli corresponding to the known in vivo sensitivity of the lung microvasculature. Using the TGase-substrate 5-(biotinamido)-pentylamine, specific TGase inhibitors and RNAi, one target protein of TGase1 in endothelial cells was found to be beta-actin, suggesting that tissue-specific stabilization of the cortical actin filament network by intracellular TGase1 activity may play a role in controlling barrier properties of endothelial monolayers.