Dynamics of Beta1-Integrins in Living Fibroblasts - Effect of Substratum Wettability

Abstract

The dynamics of integrin receptors mobility was studied in living human fibroblasts using fluorescence-labeled b1-integrin monoclonal antibodies. Time-lapse image series were obtained by confocal laser scanning microscopy when cells were adhering on model hydrophilic (clean glass) and hydrophobic (octadecyl-silanized; i.e., ODS) surfaces coated with fibronectin. Direct measurements showed approximately twice-higher velocity of integrins on glass compared to ODS, and these velocities varied in different zones of the cells. A kinetic model and algorithm for quantification of images was developed, and the analysis identified three receptor populations on glass: immobilized (82.76% of all), slow (4.16%), and fast (13.08%), while, on ODS, only two were identified: immobilized (83.36%) and fast (16.64%). Fast integrins in the peripheral zone of cells have maximal velocities of 0.35360.02 mm/min (n¼48, four cells) on hydrophilic and 0.21860.02 mm/min (n¼30, three cells) on hydrophobic substrata. The slow population has a velocity of 0.114 mm/min (n ¼ 48, four cells). Further analyses show that these velocities also differ significantly in the peripheral and middle zones of cells in a substrate-dependent fashion.Awell-defined circular motion of receptors around the cell center expressed mainly on hydrophobic substrata was monitored and quantified as well.