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Mechanobiology of Disease
Thursday Speaker Abstracts
34
Single Molecule Force Measurements in Living Cells Reveal a Minimally Tensioned
Integrin State
Alexander Dunn
.
Stanford University, Stanford, CA, USA.
Integrins mediate cell adhesion to the extracellular matrix and enable the construction of
complex, multicellular organisms, yet fundamental aspects of integrin-based adhesion remain
poorly understood. Notably, the magnitude of the mechanical load experienced by individual
integrins within living cells is unclear, due principally to limitations inherent in existing
techniques. Here we use FRET-based molecular tension sensors (MTSs) to directly measure the
distribution of loads experienced by individual integrins in primary dermal fibroblasts. We find
that the majority of integrins transmit relatively modest forces of less than 11 pN, and that a large
minority bear loads of less than 3 pN. Our data also indicate that interactions with the fibronectin
synergy site, a secondary binding site specifically for α5β1 integrin, lead to increased recruitment
of α5β1 integrin to adhesions but not to an increase in overall cellular traction generation.
Engagement with the synergy site does, however, increase cells’ resistance to detachment by
externally applied loads. In total, these observations suggest that a substantial population of
bound but minimally tensioned integrins may provide cells and tissues with physical resiliency in
the presence of widely varying mechanical loads.