α8 Integrin overexpression in de-differentiated vascular smooth muscle cells attenuates migratory activity and restores the characteristics of the differentiated phenotype

Loss of the differentiated (contractile) phenotype of vascular smooth muscle cells (VSMCs) heightens their migratory activity. Integrins, as the main integrators of cell-extracellular matrix, regulate different aspects of cell behavior including migration and differentiation. α8β1 Integrin being expressed in cell types with contractile abilities is downregulated during VSMC phenotype modulation. In this report the ability of α8β1 integrin to induce the characteristics of the contractile phenotype as well as suppression of VSMC migratory activity was investigated. Forced expression of α8 integrin in passage-5 rat VSMCs resulted in lower migratory activity. Western blot and immunoconfocal studies revealed that α8 integrin overexpression was associated with the reappearance of VSMC contractile hallmarks including upregulation of contractile markers, assembly of stress fibres, and increased number of focal adhesions. α8 Integrin overexpression in fibroblast-like Rat1 cells also induced SMC-like characteristics. α8 Integrin-induced reappearance of the contractile hallmarks in de-differentiated VSMCs was impaired by RhoA inhibitors. These results provide evidences that α8 integrin overexpression may assist phenotype-modulated VSMCs to revert to the contractile phenotype possibly via RhoA signaling pathway. Our findings suggest a dynamic role for α8β1 integrin to induce contractile phenotype as well as suppression of VSMC migration, a key player during arterial stenosis.