P406Focal adhesions: hot spots for vascular smooth muscle cell activation

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Abstract

Purpose

Vascular smooth muscle cells (VSMCs) can switch from quiescent-contractile to migratory-activated states contributing to the formation of neointima and atherosclerotic plaque. This process is responsible for the onset and progression of the principal cardiovascular proliferative disorders. In the present study, a gel-free proteomic approach was proposed to highlight factors modulated during VSMC activation.

Methods

Protein extracts from quiescent and activated VSMCs were eluted by SPE chromatography and digested with trypsin. Peptide mixtures were fractioned by HPLC and collected for MALDI TOF/TOF analysis. Differential protein expressions were analysed using spectral counts and some were validated by ELISA assay and Western blot. Immuno-fluorescence confocal microscopy was used to evidence differences in protein localization in both phenotypes.

Results

Among the 356 identified proteins, 20 were found markedly altered in activated VSMCs, many of which are directly involved in regulation of contraction and/or cell migration. Eight out of 20 differentially modulated proteins (Fibronectin, Vimentin, Vinculin, Filamin A, LASP, Talin-1, PDZ and LIM domain protein1) are directly involved in the development of focal adhesions. Immuno-fluorescence confocal microscopy was used to evidence colocalization of Vinculin and Talin-1 in activated phenotype (Fig).

Conclusion

Several of the identified and modulated proteins are related to focal adhesion pathway, indicating a pivotal role of these structures in the onset of the pathological phenotype. These proteins have been demonstrated to bind Integrins or to be involved in the Integrin signaling suggesting possible targets (Integrin firstly) for oligonucleotide-based drug cell therapy and for therapeutic application in proliferative disorders.

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