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Abstract

Mechanical stress has been shown in vitro to modulate integrin-β1-mediated activation of p125^FAK/FAK. To test the hypothesis whether this also applies to periodontal ligament fibroblasts (PDLs), we subjected human PDLs to mechanical stretch and analyzed stress-induced changes of p125^FAK activation by quantitative immunoprecipitation of p125^FAK and changes in the topography of molecules localizing in focal adhesions by indirect immunofluorescence. Generally, all components of focal contacts under study-including detection of phosphotyrosine, i.e., integrin-β1, p125^FAK, and paxillin-revealed a relative co-localization during stretch application. Under stretch, we observed a re-distribution of all components from the cell periphery to the cytoplasm following the main axes. Tyrosine phosphorylation of p125^FAK was monitored up to 72 hours under stretch. While the amount of p125^FAK remained essentially constant, the activation of p125^FAK was clearly modulated. Tyrosine phosphorylation of p125^FAK increased from 15 minutes up to 1 hour and declined after stretching periods of 24, 48, and 72 hours. The analysis of our data indicated a stretch-induced re-distribution of focal adhesion components and a modulation of p125^FAK activation, suggesting alterations in focal adhesions and their associated signal cascade.

Keywords

integrins p125FAK/FAK paxillin PDL fibroblasts stretching

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Topographic Changes of Focal Adhesion Components and Modulation of p125FAK Activation in Stretched Human Periodontal Ligament Fibroblasts

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