Alpha1beta1 and integrin-linked kinase interact and modulate angiotensin II effects in vascular smooth muscle cells

Abstract

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.

Integrin signaling in atherosclerosis

“…However, integrin signaling may also contribute to vasoconstriction, as treatment with the integrin inhibitor RGDS reduced vasoconstriction to AngII but not other vasoconstrictors [198]. While α1β1 has largely been implicated in maintaining the contractile phenotype in atherosclerosis, smooth muscle hypertrophy to chronic AngII stimulation is reduced in α1 knockout mice [199], and inhibiting α1β1 using siRNA knockdown or peptide inhibitors blunts AngII-induced ERK activation and proliferation [195, 200]. Consistent with this association, AngII promotes α1 integrin expression [199] along with the expression of multiple provisional matrix-binding integrins, such as α8, β1, and β3 [201, 202].…”

Metalloproteases Affecting Blood Coagulation, Fibrinolysis and Platelet Aggregation from Snake Venoms: Definition and Nomenclature of Interaction Sites

“…In addition, they also exhibit uniquely exclusive effects on smooth muscle cells [191,192], fibroblast-like cells [193,194], chondrocytes [195], osteoblasts [196], and neuronal progenitors [197]. Recent studies using obtustatin has shown that α 1 β 1 integrin and integrin-linked kinase modulate angiotensin II effects in vascular smooth muscle cells and thus, are potential targets to the development of more effective therapeutic interventions in cardiovascular diseases [198,199]. Thus, D and C domains selectively target specific integrins and play critical role in our understanding of cell biology.…”

A novel role for integrin‐linked kinase in periodic mechanical stress‐mediated ERK1/2 mitogenic signaling in rat chondrocytes

“…Periodic mechanical stress enhances ILK activity ILK is widely considered to be an intracellular adaptor that couples integrins modulating multiple cellular responses (Bhattacharya et al, 2015;Moraes et al, 2015). Hsu et al (2007) reported that ultrasound stimulation significantly enhanced the catalytic activity of ILK, leading to increased COX-2 expression in chondrocytes.…”