RESUMO
The effects of angiotensin II (Ang II) on vascular smooth muscle cells (VSMC) are modulated by reactive oxygen species (ROS) and also involve integrin engagement. However, the potential link between alpha1beta1 integrin signaling with NOX system and their combined contribution to Ang II effects on VSMC have not been investigated. We aimed to elucidate the moslecular mechanisms underlying the activation of these two pathways in Ang II effects on VSMC. Ang II-induced VSMC migration (2-fold increase) and proliferation (2.5-fold increase) is modulated by alpha1beta1 integrin, being inhibited by obtustatin, a specific alpha1beta1 integrin blocker. Ang II also stimulates ROS production in VSMC (140%) that is NOX1 dependent, being completely inhibited in NOX1 silenced cells. The ROS production develops in two peaks, and the second peak is maintained by NOX2 activation. Apocynin and obtustatin inhibit the NOX2-associated second peak, but not the first peak of ROS production, which is related to NOX1 activation. Corroborating the involvement of alpha1beta1 integrin, the pretreatment of VSMC with obtustatin impaired Ang II-induced FAK phosphorylation, AKT activation, p21 degradation and the increase of ILK expression. Silencing of ILK blocked cell migration, AKT phosphorylation and the second peak of ROS, but partially inhibits (70%) VSMC proliferation induced by Ang II. The data demonstrate a novel role for NOX2 in Ang II effects on VSMC, and suggest alpha1beta1 integrin and ILK as target molecules to the development of more effective therapeutic interventions in cardiovascular diseases.
Assuntos
Angiotensina II/farmacologia , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Integrina alfa1beta1/metabolismo , Músculo Liso Vascular/efeitos dos fármacos , Miócitos de Músculo Liso/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/metabolismo , Acetofenonas/farmacologia , Animais , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/enzimologia , Células Cultivadas , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Inibidores Enzimáticos/farmacologia , Quinase 1 de Adesão Focal/metabolismo , Integrina alfa1beta1/antagonistas & inibidores , Masculino , Glicoproteínas de Membrana/antagonistas & inibidores , Glicoproteínas de Membrana/metabolismo , Músculo Liso Vascular/enzimologia , Miócitos de Músculo Liso/enzimologia , NADH NADPH Oxirredutases/genética , NADH NADPH Oxirredutases/metabolismo , NADPH Oxidase 1 , NADPH Oxidase 2 , NADPH Oxidases/antagonistas & inibidores , NADPH Oxidases/metabolismo , Fosforilação , Proteínas Serina-Treonina Quinases/genética , Proteólise , Proteínas Proto-Oncogênicas c-akt/metabolismo , Interferência de RNA , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fatores de Tempo , Transfecção , Venenos de Víboras/farmacologiaRESUMO
The aim of our study was to investigate the osteoinductive potential of a titanium (Ti) surface with nanotopography, using mesenchymal stem cells (MSCs) and the mechanism involved in this phenomenon. Polished Ti discs were chemically treated with H2 SO4 /H2 O2 to yield nanotopography and rat MSCs were cultured under osteogenic and non-osteogenic conditions on both nanotopography and untreated polished (control) Ti surfaces. The nanotopography increased cell proliferation and alkaline phosphatase (Alp) activity and upregulated the gene expression of key bone markers of cells grown under both osteogenic and non-osteogenic conditions. Additionally, the gene expression of α1 and ß1 integrins was higher in cells grown on Ti with nanotopography under non-osteogeneic condition compared with control Ti surface. The higher gene expression of bone markers and Alp activity induced by Ti with nanotopography was reduced by obtustatin, an α1ß1 integrin inhibitor. These results indicate that α1ß1 integrin signaling pathway determines the osteoinductive effect of nanotopography on MSCs. This finding highlights a novel mechanism involved in nanosurface-mediated MSCs fate and may contribute to the development of new surface modifications aiming to accelerate and/or enhance the process of osseointegration.