Abstract 16436: A Dual Role of Cell Adhesion Molecule Necl-4 in Endothelial Cells: Promotion of Migration Under Sparse Conditions and Inhibition of Proliferation Under Confluent Conditions
Background: Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis, and VEGF receptor 2 (VEGFR2) mainly mediates pro-angiogenic activities of vascular endothelial cells (ECs). Recently we have reported that nectin-like molecule (Necl)-5, a member of the immunoglobulin-like cell adhesion molecules Necls, interacts with VEGFR2 and enhances VEGFR2-mediated signaling, leading to increasing pro-angiogenic activities. Here we show that Necl-4, also known as cell adhesion molecule 4 (CADM4), also regulates VEGFR2-mediated pro-angiogenic activities and signaling by a mechanism different form Necl-5, and contact inhibition of proliferation of ECs.
Results: Under sparse conditions, Necl-4 was localized at the leading edge of migrating human umbilical vein ECs in culture, and knockdown of Necl-4 increased Rho-associated protein kinase (ROCK) activity and reduced VEGF-induced migration, capillary-like network formation, and activation of Rac1 small GTPase. These reductions were partly restored by specific ROCK inhibitors Y-27632 and fasudil or by additional knockdown of tyrosine-protein phosphatase non-receptor type 13 (PTPN13) that interacts with Necl-4. On the other hand, under confluent conditions, Necl-4 was up-regulated and localized at the cell-cell contact sites, and knockdown of Necl-4 or PTPN13 increased, whereas overexpression of Necl-4 decreased, VEGF-induced phosphorylation of VEGFR2. Overexpression of Necl-4 reduced VEGF-induced proliferation.
Conclusions: We first revealed that Necl-4 has a dual role in migration and proliferation of ECs depending on cell density and localization of Necl-4. Necl-4 localized at the leading edge enhanced the VEGF-induced migration and network formation by facilitating Rac1 activation through inhibiting the PTPN13-ROCK pathway, whereas when ECs reach confluence up-regulated Necl-4 was localized at the cell-cell contact sites where it contributes to contact inhibition of proliferation by inhibiting VEGFR2 phosphorylation through PTPN13.
Author Disclosures: S. Yamana: None. A. Tokiyama: None. Y. Terao: None. K. Hirata: None. Y. Rikitake: None.
- © 2014 by American Heart Association, Inc.