Sustained α-catenin Activation at E-cadherin Junctions in the Absence of Mechanical Force.
Mechanotransduction at E-cadherin junctions has been postulated to be mediated in part by a force-dependent conformational activation of α-catenin. Activation of α-catenin allows it to interact with vinculin in addition to F-actin, resulting in a strengthening of junctions. Here, using E-cadherin adhesions reconstituted on synthetic, nanopatterned membranes, we show that activation of α-catenin is dependent on E-cadherin clustering, and is sustained in the absence of mechanical force or association with F-actin or vinculin. Adhesions were formed by filopodia-mediated nucleation and micron-scale assembly of E-cadherin clusters, which could be distinguished as either peripheral or central assemblies depending on their relative location at the cell-bilayer adhesion. Whereas F-actin, vinculin, and phosphorylated myosin light chain associated only with the peripheral assemblies, activated α-catenin was present in both peripheral and central assemblies, and persisted in the central assemblies in the absence of actomyosin tension. Impeding filopodia-mediated nucleation and micron-scale assembly of E-cadherin adhesion complexes by confining the movement of bilayer-bound E-cadherin on nanopatterned substrates reduced the levels of activated α-catenin. Taken together, these results indicate that although the initial activation of α-catenin requires micron-scale clustering that may allow the development of mechanical forces, sustained force is not required for maintaining α-catenin in the active state.
Mechanobiology Institute, National University of Singapore, Singapore, Singapore. Electronic address: mbikhb@nus.edu.sg.
Kabir H
KH
Biswas
Mechanobiology Institute, National University of Singapore, Singapore, Singapore; Department of Chemistry, University of California, Berkeley, Berkeley, California.
Kevin L
KL
Hartman
Mechanobiology Institute, National University of Singapore, Singapore, Singapore; Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore. Electronic address: zaidelbar@gmail.com.
Ronen
R
Zaidel-Bar
Mechanobiology Institute, National University of Singapore, Singapore, Singapore; Department of Chemistry, University of California, Berkeley, Berkeley, California; Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore. Electronic address: jtgroves@lbl.gov.
Jay T
JT
Groves
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D015703:Antigens, CD; D015820:Cadherins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry; D040542:Mechanotransduction, Cellular / Q000187:drug effects / Q000502:physiology*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D018994:Myosin Light Chains / Q000737:chemistry / Q000378:metabolism; D013314:Stress, Mechanical; D016596:Vinculin / Q000737:chemistry / Q000378:metabolism; D051178:alpha Catenin / Q000737:chemistry / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism
D000199:Actins; D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D008051:Lipid Bilayers; D018994:Myosin Light Chains; D051178:alpha Catenin; D016596:Vinculin; D049452:Green Fluorescent Proteins; D054460:rho-Associated Kinases