Paracingulin controls the junctional accumulation of nonmuscle myosin-2 in endothelial cells in vivo

The localization of nonmuscle myosin-2 (NM2) isoforms in endothelial cells and the mechanisms that regulate their localizations are poorly understood. Here we show that NM2A and NM2B are localized at junctions of mouse aortic endothelial cells in vivo, whereas only NM2B is detectable at junctions of cultured bEnd.3 endothelial cells. In both models, the knockout of the junctional protein paracingulin results in the loss of the junctional localization of NM2s. These results demonstrate the physiological relevance of our previous in vitro observations on epithelial cells, provide a mechanism for the localization of NM2s at endothelial junctions, and raise new questions for future studies.