Abstract 5556: Immunoglobulin-like Cell Adhesion Molecule Necl-5 Regulates Vascular Endothelial Growth Factor-Induced Angiogenesis by Controlling the Interaction Between VEGFR2 and Integrin αvβ3
Background Peripheral arterial disease (PAD) is highly prevalent worldwide. PAD is a major cause of lower limb amputation, which is associated with a poor quality of life and prognosis. Vascular endothelial growth factor (VEGF) is a key pro-angiogenic cytokine proposed as therapeutic angiogenesis for PAD. However, more investigation is needed to better understand VEGF-induced angiogenesis and its application to PAD. The activity of VEGF receptor 2 (VEGFR2) is regulated by direct interactions with VEGF and other cell surface proteins, including integrin αvβ3. However, the regulation mechanism of VEGFR2 and integrin αvβ3 interaction has not been established. Nectin-like molecules (Necls) are immunoglobulin-like cell adhesion molecules (CAMs) that regulate cell movement, proliferation and survival. Here we show that Necl-5, a member of Necls that binds integrin αvβ3, regulates the interaction between VEGFR2 and integrin αvβ3 in vascular endothelial cells (ECs) and that this CAM plays an important role in angiogenesis.
Methods and Results Immunohistochemistry revealed that Necl-5 was preferentially expressed in ECs including mouse hind limb capillary endothelium. Flow cytometry showed that Necl-5 was expressed in various cultured ECs. Although Necl-5-knockout mice displayed no obvious defect in vascular development, these mice exhibited impaired adaptive angiogenesis following hind limb ischemia. To clarify the regulation mechanism of angiogenesis by Necl-5, we knocked down Necl-5 by siRNA and studied the role of Necl-5 in angiogenesis in vitro. VEGF-induced tube formation on Matrigel, migration, and proliferation were significantly inhibited in Necl-5-knockdown ECs. Conversely, serum deprivation-induced apoptosis was enhanced in Necl-5-knockdown ECs. Knockdown of Necl-5 prevented VEGF-induced interaction of integrin αvβ3 with VEGFR2, and then suppressed the VEGFR2-mediated activation of Akt, a critical signal for angiogenesis and cell survival.
Conclusions These findings indicate that Necl-5 regulates VEGF-induced angiogenesis by controlling the interaction between VEGFR2 and integrin αvβ3, and the VEGFR2-mediated signaling. Therapeutic intervention of Necl-5 may represent a novel strategy in the patients with PAD.