Email updates

Keep up to date with the latest news and content from BMC Biophysics and BioMed Central.

Open Access Highly Accessed Research article

Probabilistic modeling and analysis of the effects of extra-cellular matrix density on the sizes, shapes, and locations of integrin clusters in adherent cells

Erik S Welf1, Ulhas P Naik12 and Babatunde A Ogunnaike1*

Author Affiliations

1 Department of Chemical Engineering, 150 Academy St, Colburn Lab, University of Delaware, Newark, Delaware 19716, USA

2 Department of Biological Sciences, 309 Wolf Hall, University of Delaware, Newark, Delaware 19716, USA

For all author emails, please log on.

BMC Biophysics 2011, 4:15  doi:10.1186/2046-1682-4-15

Published: 9 August 2011

Abstract

Background

Regulation of integrin binding to the specific complementary sites on extra-cellular matrix (ECM) proteins plays a major role in cell adhesion and migration. In addition to regulating single integrin-ligand bonds by affinity modulation, cells regulate their adhesiveness by forming integrin clusters. Although it is clear that cells exhibit different adhesion and migration behaviors on surfaces coated with different concentrations of ECM proteins, it is not clear if this response is mediated by changes in the availability of integrin binding sites or by differential intracellular signaling that may affect integrin binding and clustering.

Results

To quantify how the concentration of ECM affects integrin clustering, we seeded cells expressing the integrin αIIbβ3 on different concentrations of the complementary ECM protein fibrinogen (Fg) and measured the resulting integrin cluster properties. We observed heterogeneity in the properties of integrin clusters, and to characterize this population heterogeneity we use a probabilistic modeling approach to quantify changes to the distributions of integrin cluster size, shape, and location.

Conclusions

Our results indicate that in response to increasing ECM density cells form smaller integrin clusters that are less elongated and closer to the cell periphery. These results suggest that cells can sense the availability of ECM binding sites and consequently regulate integrin clustering as a function of ECM density.