Abstract 20232: Cdc42 Inhibits Tail Retraction in Migrating Endothelial Cells by Stabilizing Microtubules
During vascular branch morphogenesis, the leading tip cell must precisely control its tail retraction speed during migration in order to maintain its contact with stalk cells to prevent branch disintegration. To explore the molecular mechanisms underlying this fundamental process, we isolated endothelial cells from primitive capillaries formed during the differentiation of embryonic stem (ES) cells into embryoid bodies. These ES cell-derived endothelial cells are highly migratory and possess prominent lamellipodia/filopodia and a trailing edge. Our immunofluorescence study revealed for the first time that the polarity proteins Cdc42, Par-6, and protein kinase Ciota (PKCiota) are expressed in a bipolar pattern, accumulating at the trailing edge as well as the front protrusion of migrating cells. The trailing edge is also enriched with microtubule filaments. Expression of dominant negative Cdc42 or inhibition of PKCiota disassembles the microtubule filaments and causes tail retraction. Similarly, treatment of the cells with the microtubule-disrupting agent nocodazole also leads to the release of the trailing edge. By contrast, inhibition of Rho kinase (ROCK), a RhoA effector, with Y27632 prevents tail retraction. These results suggest that Cdc42-mediated microtubule stabilization antagonizes RhoA-dependent actomyosin contractions to inhibit tail retraction in migrating endothelial cells. This regulated tail retention may facilitate the formation of cell-cell junctions between tips cells and stalk cells, and thereby promote endothelial branch morphogenesis.
- © 2010 by American Heart Association, Inc.