Journal of Dental Research, Vol 80, 1984-1989, Copyright © 2001 by International & American Associations for Dental Research Online Journals
Topographic changes of focal adhesion components and modulation of p125FAK activation in stretched human periodontal ligament fibroblasts
T. Molina, K. Kabsch, A. Alonso, A. Kohl, G. Komposch and P. Tomakidi
Department of Orthodontics and Dentofacial Orthopedics, Dental School, University of Heidelberg, Germany.
Mechanical stress has been shown in vitro to modulate
integrin-beta1-mediated activation of p125FAK/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 p125FAK activation by quantitative immunoprecipitation of
p125FAK 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-beta1, p125FAK, 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 p125FAK was monitored up to 72 hours
under stretch. While the amount of p125FAK remained essentially constant,
the activation of p125FAK was clearly modulated. Tyrosine phosphorylation
of p125FAK 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 redistribution of focal adhesion components and
a modulation of p125FAK activation, suggesting alterations in focal
adhesions and their associated signal cascade.
