Human Angiomotin-Like 1 Associates With an Angiomotin Protein Complex Through Its Coiled-Coil Domain and Induces the Remodeling of the Actin Cytoskeleton

Angiostatin is a potent inhibitor of angiogenesis. One mechanism through which angiostatin inhibits angiogenesis is by binding to the cell surface protein p80-angiomotin. The p80-angiomotin protein promotes angiogenesis, in part, by conferring a hypermigratory phenotype to endothelial cells. Although p80-angiomotin is extensively characterized, less is known about the related protein angiomotin-like 1. We report that angiomotin-like 1 forms part of a protein complex containing p80-angiomotin. Structure-function studies revealed that angiomotin-like 1 associates with this p80-angiomotin-containing complex via its coiled-coil domain. Since p80-angiomotin plays a role in cell migration, a process that involves the remodeling of the actin cytoskeleton, we then addressed the hypothesis that angiomotin-like 1 may interact with the cytoskeleton. Immunofluorescence studies reveal that angiomotin-like 1 not only co-localizes with filamentous actin but also significantly modifies the architecture of the actin cytoskeleton. Regarding migration, angiomotin-like 1 increases the velocity of migration and decreases the persistence of migration directionality. Together these observations strongly suggest that angiomotin-like 1 is involved in actin-cytoskeleton-based processes, in part, via its interaction with a p80-angiomotin-containing complex and the actin cytoskeleton. These findings have important implications for angiogenesis-driven disease since angiomotin and angiomotin-like 1 are both expressed in capillaries. Cell Motil. Cytoskeleton 66: 754-768, 2009. (C) 2009 Wiley-Liss, Inc.