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

## TL;DR

This study shows how a protein called paracingulin helps position a muscle-related protein at cell junctions in blood vessel cells.

## Contribution

The study demonstrates that paracingulin is essential for the junctional localization of nonmuscle myosin-2 in endothelial cells in vivo.

## Key findings

- NM2A and NM2B are found at junctions in mouse aortic endothelial cells in vivo.
- Paracingulin knockout removes NM2 localization at endothelial junctions in both in vivo and cultured cells.
- The findings confirm previous in vitro results and suggest a regulatory mechanism for NM2 localization.

## Abstract

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.