title: Dynamic visualization of α-catenin reveals rapid, reversible conformation switching between tension states.
abstract: The cytosolic protein α-catenin is a postulated force transducer at cadherin complexes. The demonstration of force activation, identification of consequent downstream events in live cells, and development of tools to study these dynamic processes in living cells are central to elucidating the role of α-catenin in cellular mechanics and tissue function. Here we demonstrate that α-catenin is a force-activatable mechanotransducer at cell-cell junctions by using an engineered α-catenin conformation sensor based on fluorescence resonance energy transfer (FRET). This sensor reconstitutes α-catenin-dependent functions in α-catenin-depleted cells and recapitulates the behavior of the endogenous protein. Dynamic imaging of cells expressing the sensor demonstrated that α-catenin undergoes immediate, reversible conformation switching in direct response to different mechanical perturbations of cadherin adhesions. Combined magnetic twisting cytometry with dynamic FRET imaging revealed rapid, local conformation switching upon the mechanical stimulation of specific cadherin bonds. At acutely stretched cell-cell junctions, the immediate, reversible conformation change further reveals that α-catenin behaves like an elastic spring in series with cadherin and actin. The force-dependent recruitment of vinculin—a principal α-catenin effector—to junctions requires the vinculin binding site of the α-catenin sensor. In cells, the relative rates of force-dependent α-catenin conformation switching and vinculin recruitment reveal that α-catenin activation and vinculin recruitment occur sequentially, rather than in a concerted process, with vinculin accumulation being significantly slower. This engineered α-catenin sensor revealed that α-catenin is a reversible, stretch-activatable sensor that mechanically links cadherin complexes and actin and is an indispensable player in cadherin-specific mechanotransduction at intercellular junctions.
authors.affiliation: Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Tae-Jin
authors.initials: TJ
authors.lastname: Kim
authors.affiliation: Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Shuai
authors.initials: S
authors.lastname: Zheng
authors.affiliation: Department of Integrative and Molecular Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Ismaeel
authors.initials: I
authors.lastname: Muhamed
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Wu
authors.affiliation: Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Lei
authors.affiliation: Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Kong
authors.affiliation: Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. Electronic address: leckband@illinois.edu.
authors.forename: Deborah E
authors.initials: DE
authors.lastname: Leckband
authors.affiliation: Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Bioengineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Integrative and Molecular Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Bioengineering and Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA 92093, USA. Electronic address: yiw015@eng.ucsd.edu.
authors.forename: Yingxiao
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000199:Actins / Q000378:metabolism; D015820:Cadherins / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D005786:Gene Expression Regulation; D006801:Humans; D007365:Intercellular Junctions; D040542:Mechanotransduction, Cellular; D011485:Protein Binding; D051178:alpha Catenin / Q000235:genetics* / Q000378:metabolism
chemical_list: D000199:Actins; C495273:CTNNA1 protein, human; D015820:Cadherins; D051178:alpha Catenin