RESUMO
Disabled-2 (DAB2) is an adaptor protein implicated in signal transduction pathways and in protein traffic regulation. Here, we show that DAB2 is highly expressed in human endothelial cells. DAB2 silencing in endothelial cells by lentiviral-mediated small hairpin RNA expression affects cell migration and differentiation into capillary-like structures while increasing cell proliferation and viability. DAB2 knockdown causes activation of the Src-FAK signal pathway, extracellular-signal regulated kinase and c-Jun NH2-terminal kinase activation, and inhibition of p38 phosphorylation. In DAB2 silenced endothelial cells, pharmacological inhibition of Src with its specific inhibitor PP2 abolishes focal adhesion kinase activation and restores differentiation of endothelial cells. These results suggest that DAB2, via Src and focal adhesion signaling, plays a role in human endothelial cell function.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/fisiologia , Diferenciação Celular , Endotélio Vascular/crescimento & desenvolvimento , Neovascularização Fisiológica , Quinases da Família src/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Proteínas Reguladoras de Apoptose , Diferenciação Celular/genética , Movimento Celular/genética , Células Cultivadas , Endotélio Vascular/metabolismo , Quinase 1 de Adesão Focal/genética , Quinase 1 de Adesão Focal/metabolismo , Inativação Gênica , Humanos , Camundongos , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Morfogênese , Neovascularização Fisiológica/genética , RNA Interferente Pequeno/genética , Proteínas Supressoras de Tumor , Quinases da Família src/antagonistas & inibidoresRESUMO
Vascular endothelial growth factor (VEGF)-D is a member of the VEGF family of angiogenic growth factors that recognizes and activates the vascular endothelial growth factor receptor (VEGFR)-2 and VEGFR-3 on blood and/or lymphatic vessels. We show that in the long bones of newborn mice, VEGF-D and VEGFR-3 are expressed in the osteoblasts of the growing plate. The treatment of primary human osteoblasts with recombinant VEGF-D induces the expression of osteocalcin and the formation of mineralized nodules in a dose-dependent manner. A monoclonal neutralizing antibody, anti-VEGF-D, or silencing of VEGFR-3 by lentiviral-mediated expression of VEGFR-3 small hairpin RNA affects VEGF-D-dependent osteocalcin expression and nodule formation. Moreover, in primary human osteoblasts, VEGF-D expression is under the control of VEGF, and inhibition of VEGF-D/VEGFR-3 signaling, by monoclonal antibodies or VEGFR-3 silencing, affects VEGF-dependent osteoblast differentiation. These experiments establish that VEGF-D/VEGFR-3 signaling plays a critical role in osteoblast maturation and suggest that VEGF-D is a downstream effector of VEGF in osteogenesis.