Diacylglycerol kinase-alpha mediates hepatocyte growth factor-induced epithelial cell scatter by regulating Rac activation and membrane ruffling

• Published in: Molecular biology of the cell 2007-12, Vol.18 (12), p.4859-4871
• Main Authors: Chianale, Federica, Cutrupi, Santina, Rainero, Elena, Baldanzi, Gianluca, Porporato, Paolo E, Traini, Sara, Filigheddu, Nicoletta, Gnocchi, Viola F, Santoro, Massimo M, Parolini, Ornella, van Blitterswijk, Wim J, Sinigaglia, Fabiola, Graziani, Andrea
• Format: Article
• Language: English
• Subjects: Animals; Cadherins - metabolism; Cell Adhesion - drug effects; Cell Differentiation - drug effects; Cell Line; Cell Membrane - drug effects; Cell Membrane - enzymology; Cell Movement - drug effects; Cytoskeleton - drug effects; Cytoskeleton - metabolism; Diacylglycerol Kinase - genetics; Diacylglycerol Kinase - metabolism; Down-Regulation - drug effects; Enzyme Activation - drug effects; Epithelial Cells - cytology; Epithelial Cells - drug effects; Epithelial Cells - enzymology; Hepatocyte Growth Factor - pharmacology; Humans; Protein Binding; rac GTP-Binding Proteins - metabolism
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.E07-02-0177

Diacylglycerol kinases (Dgk) phosphorylate diacylglycerol (DG) to phosphatidic acid (PA), thus turning off and on, respectively, DG-mediated and PA-mediated signaling pathways. We previously showed that hepatocyte growth factor (HGF), vascular endothelial growth factor, and anaplastic lymphoma kinase activate Dgkalpha in endothelial and leukemia cells through a Src-mediated mechanism and that activation of Dgkalpha is required for chemotactic, proliferative, and angiogenic signaling in vitro. Here, we investigate the downstream events and signaling pathways regulated by Dgkalpha, leading to cell scatter and migration upon HGF treatment and v-Src expression in epithelial cells. We report that specific inhibition of Dgkalpha, obtained either pharmacologically by R59949 treatment, or by expression of Dgkalpha dominant-negative mutant, or by small interfering RNA-mediated down-regulation of endogenous Dgkalpha, impairs 1) HGF- and v-Src-induced cell scatter and migration, without affecting the loss of intercellular adhesions; 2) HGF-induced cell spreading, lamellipodia formation, membrane ruffling, and focal adhesions remodeling; and 3) HGF-induced Rac activation and membrane targeting. In summary, we provide evidence that Dgkalpha, activated downstream of tyrosine kinase receptors and Src, regulates crucial steps directing Rac activation and Rac-dependent remodeling of actin cytoskeleton and focal contacts in migrating epithelial cells.