title: VEGF treatment induces signaling pathways that regulate both actin polymerization and depolymerization.
abstract: The angiogenic growth factor vascular endothelial growth factor (VEGF) enhances endothelial cell migration through the activation of multiple signaling transduction pathways. Actin reorganization is an important component in VEGF-induced migration, yet the signaling pathways mediating this process remain unclear. Actin reorganization involves both actin polymerization and depolymerization, and in this study we demonstrate that VEGF-treatment regulates both of these activities. With respect to actin polymerization, our results indicate that the actin nucleation promoting factors (NPF) neural Wiskott-Aldrich syndrome protein (N-WASP) binds the SH2- plus SH3-domain containing adaptor protein Nck in both control and VEGF-treated cells. We had previously showed that VEGF treatment leads to the recruitment of Nck to activated receptor, and our current results indicate a VEGF-dependent redistribution of N-WASP to the cell surface. A Nck dominant-negative blocked Nck recruitment to receptor, blocked N-WASP cellular redistribution and attenuated actin stress fiber formation. With respect to actin depolymerization, VEGF-treatment led to the rapid phosphorylation of the actin depolymerization factor cofilin, and its upstream regulator, LIM-kinase (LIMK). Unlike what is observed in certain other cell types, the p21-activated kinase (PAK), a Nck binding protein, does not mediate VEGF-induced LIMK phosphorylation, as a PAK dominant-negative had no effect on this activity. The PAK dominant-negative also did not affect VEGF-induced actin reorganization. Pharmacological inhibitors of phosphoinositide-3 kinase (PI3-K) and the rho-activated kinase (ROCK) attenuated VEGF-induced LIMK phosphorylation, indicating a role for (PI3-K) and ROCK in the signaling pathways leading to regulation of LIMK activity.
authors.affiliation: Cardiology Division, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA.
authors.forename: Chunhong
authors.initials: C
authors.lastname: Gong
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Stoletov
authors.forename: Bruce I
authors.initials: BI
authors.lastname: Terman
mesh_terms: D000199:Actins / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D001704:Biopolymers / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D015513:Oncogene Proteins / Q000378:metabolism; D011485:Protein Binding; D015398:Signal Transduction / Q000187:drug effects*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal / Q000378:metabolism
chemical_list: D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D001704:Biopolymers; C078332:Nck protein; D015513:Oncogene Proteins; D042461:Vascular Endothelial Growth Factor A; C495771:WASL protein, human; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal