title: Integrin Molecular Tension within Motile Focal Adhesions.
abstract: Forces transmitted by integrins regulate many important cellular functions. Previously, we developed tension gauge tether (TGT) as a molecular force sensor and determined the threshold tension across a single integrin-ligand bond, termed integrin tension, required for initial cell adhesion. Here, we used fluorescently labeled TGTs to study the magnitude and spatial distribution of integrin tension on the cell-substratum interface. We observed two distinct levels of integrin tension. A >54 pN molecular tension is transmitted by clustered integrins in motile focal adhesions (FAs) and such force is generated by actomyosin, whereas the previously reported ∼40 pN integrin tension is transmitted by integrins before FA formation and is independent of actomyosin. We then studied FA motility using a TGT-coated surface as a fluorescent canvas, which records the history of integrin force activity. Our data suggest that the region of the strongest integrin force overlaps with the center of a motile FA within 0.2 μm resolution. We also found that FAs move in pairs and that the asymmetry in the motility of an FA pair is dependent on the initial FA locations on the cell-substratum interface.
authors.affiliation: Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Department of Physics and Astronomy, Iowa State University, Ames, Iowa. Electronic address: xuefeng@iastate.edu.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Wang
authors.affiliation: Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Jie
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Qian
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Farhan
authors.initials: F
authors.lastname: Chowdhury
authors.affiliation: Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Roein-Peikar
authors.affiliation: Bioengineering Department, University of California San Diego, La Jolla, California.
authors.forename: Yingxiao
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Physics and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois; Howard Hughes Medical Institute, Johns Hopkins University, Baltimore, Maryland; Department of Biophysics & Biophysical Chemistry, Department of Biophysics, and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Taekjip
authors.initials: T
authors.lastname: Ha
mesh_terms: D000205:Actomyosin / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D001696:Biomechanical Phenomena; D016466:CHO Cells; D002448:Cell Adhesion; D006224:Cricetinae; D003412:Cricetulus; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism*; D022001:Focal Adhesions / Q000378:metabolism*; D055767:Immobilized Proteins / Q000378:metabolism; D016023:Integrins / Q000378:metabolism; D008024:Ligands; D055595:Mechanical Phenomena
chemical_list: D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D055767:Immobilized Proteins; D016023:Integrins; D008024:Ligands; D000205:Actomyosin