Formation of adherens junctions leads to the emergence of a tissue-level tension in epithelial monolayers.
Bottom Line: Adherens junctions and desmosomes integrate the cytoskeletons of adjacent cells into a mechanical syncitium.Though much is known about the biological mechanisms underlying junction formation, little is known about how tissue-scale mechanical properties are established.As a consequence, inhibition of any of the molecular mechanisms participating in adherens junction initiation, remodelling and maturation significantly impeded the emergence of tissue-level tension in monolayers.
Affiliation: London Centre for Nanotechnology, University College London, London WC1H 0AH, UK Department of Physics, University College London, London WC1E 6BT, UK Engineering Doctorate Program, Department of Chemistry, University College London, London WC1H 0AJ, UK.Show MeSH
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Mentions: Next, we sought to correlate the initial observed increase in apparent stiffness with the formation of adherens junctions and desmosomes. The two main components of adherens junctions, E-cadherin and F-actin, localised to cell–cell contacts even at the earliest time-point investigated (Fig. 3A,B, arrowheads). E-cadherin and F-actin localisation was initially limited to the basal side of intercellular contacts (Fig. 3A,B, zx profile, 60 min) but from 150 min the height of intercellular junctions increased (Fig. 3A,B, zx profile, 150 min) and cell morphology changed from spread to cuboidal (Fig. 3A,B, zx profile). The desmosomal plaque component desmoplakin was absent from intercellular contacts at 60 min but gradually localised to junctions over the course of the next 4 h (Fig. 3C, arrowheads), consistent with previous studies (Mattey et al., 1990). Keratin 18 intermediate filaments displayed a perinuclear pattern of localisation, with little or no junctional localisation, for the first 150 min after plating, before gradually acquiring their mature localisation between 150 min and 300 min (Fig. 3D, compare 150 min, 300 min and 18 h). Taken together, these data showed that adherens junctions formed within the first 150 min after plating, coincident with the observed increase in the apparent stiffness of the monolayer. By contrast, the formation of desmosomes and a mature intermediate filament network took significantly longer. Taken together, these mechanical and protein localisation data suggested that the assembly of adherens junctions during monolayer formation led to the observed increase in monolayer apparent stiffness.
Affiliation: London Centre for Nanotechnology, University College London, London WC1H 0AH, UK Department of Physics, University College London, London WC1E 6BT, UK Engineering Doctorate Program, Department of Chemistry, University College London, London WC1H 0AJ, UK.