Dynamics of b1-Integrins in Living Fibroblasts - Effect of Substratum Wettability

¹ Bulgarian Academy of Sciences, Institute of Biophysics
² GKSS Research Center, Institute of Chemistry
³ Martin-Luther University, Institute of Biomedical Materials Bioengineering

^* To whom correspondence should be addressed. E-mail: altankov{at}obzor.bio21.bas.bg.

Submitted on February 14, 2005
Revised on April 4, 2005
Accepted on 6 July 2005

	Abstract

The dynamics of integrin receptors mobility was studied in living human fibroblasts using fluorescence-labeled 1 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, 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 0.353 0.02 µm/min (n=48, 4cells) on hydrophilic and 0.218 0.02 µm/min (n=30, 3 cells) on hydrophobic substrata. The "slow" population has a velocity of 0.114 µm/min (n=48, 4 cells). Further analyses shows that these velocities differ significantly in the peripheral and middle zones of cells also in a substrate-dependent fashion. A well defined circular motion of receptors around the cell center expressed mainly on hydrophobic substrata was monitored and quantified as well.

Key Words: hydrophilic and hydrophobic substrata, image analysis, integrin velocity and density, kinetic model