Why do receptor–ligand bonds in cell adhesion cluster into discrete focal-adhesion sites?

Journal Article · Sat May 14 00:00:00 EDT 2016 · Journal of the Mechanics and Physics of Solids

DOI:https://doi.org/10.1016/j.jmps.2016.05.012· OSTI ID:1357997

Gao, Zhiwen ^[1]; Gao, Yanfei ^[2]

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1. Lanzhou Univ. (China). Key Laboratory of Mechanics on Disaster and Environment in Western China attached to the Ministry of Education of China and Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanic; Univ. of Tennessee, Knoxville, TN (United States). Department of Materials Science and Engineering
2. Univ. of Tennessee, Knoxville, TN (United States). Department of Materials Science and Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

We report that cell adhesion often exhibits the clustering of the receptor–ligand bonds into discrete focal-adhesion sites near the contact edge, thus resembling a rosette shape or a contracting membrane anchored by a small number of peripheral forces. The ligands on the extracellular matrix are immobile, and the receptors in the cell plasma membrane consist of two types: high-affinity integrins (that bond to the substrate ligands and are immobile) and low-affinity integrins (that are mobile and not bonded to the ligands). Thus the adhesion energy density is proportional to the high-affinity integrin density. This paper provides a mechanistic explanation for the clustering/assembling of the receptor–ligand bonds from two main points: (1) the cellular contractile force leads to the density evolution of these two types of integrins, and results into a large high-affinity integrin density near the contact edge and (2) the front of a propagating crack into a decreasing toughness field will be unstable and wavy. From this fracture mechanics perspective, the chemomechanical equilibrium is reached when a small number of patches with large receptor–ligand bond density are anticipated to form at the cell periphery, as opposed to a uniform distribution of bonds on the entire interface. Finally, cohesive fracture simulations show that the de-adhesion force can be significantly enhanced by this nonuniform bond density field, but the de-adhesion force anisotropy due to the substrate elastic anisotropy is significantly reduced.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1357997
• Journal Information: Journal of the Mechanics and Physics of Solids, Vol. 95, Issue C; ISSN 0022-5096
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Receptor–ligand bond
Integrin density evolution
Cohesive interface model
Unstable crack growth
De-adhesion anisotropy