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Formation of adherens junctions leads to the emergence of a tissue-level tension in epithelial monolayers.

Harris AR, Daeden A, Charras GT - J. Cell. Sci. (2014)

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.

View Article: PubMed Central - PubMed

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.

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Actin remodelling by formins and myosin is not required for initial junction formation but is necessary for the emergence of monolayer tissue tension. (A,B) Localisation of E-cadherin–GFP and LifeAct–Ruby in control cells at 60 min (A) and 150 min (B) after replating. (C,D) Localisation of E-cadherin–GFP and LifeAct–Ruby in cells treated with the broad-spectrum formin inhibitor SMIFH2 at 60 min (C) and 150 min (D) after replating. (E,F) Localisation of E-cadherin–GFP and LifeAct–Ruby in cells treated with the Rho kinase inhibitor Y27632 at 60 min (E) and 150 min (F) after replating. In A–F, the upper images show a single xy confocal plane and the lower images show a single zx profile. The location of zx profiles is shown by dashed yellow lines on the xy images. Scale bars: 10 µm. (G) Temporal evolution of the apparent stiffness in control monolayers (black) and monolayers treated with SMIFH2 (green). (H) Temporal evolution of the apparent stiffness in control monolayers (black) and monolayers treated with Y27632 (purple) or blebbistatin (yellow). In G and H, the number of measurements for each condition is indicated below each box; boxes, median, 1st quartile and 3rd quartile; whiskers, maximum and minimum; dotted line, temporal evolution of monolayer apparent stiffness for each condition; *P<0.01 between control monolayers and treated monolayers at a given time-point (Student's t-test)
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f06: Actin remodelling by formins and myosin is not required for initial junction formation but is necessary for the emergence of monolayer tissue tension. (A,B) Localisation of E-cadherin–GFP and LifeAct–Ruby in control cells at 60 min (A) and 150 min (B) after replating. (C,D) Localisation of E-cadherin–GFP and LifeAct–Ruby in cells treated with the broad-spectrum formin inhibitor SMIFH2 at 60 min (C) and 150 min (D) after replating. (E,F) Localisation of E-cadherin–GFP and LifeAct–Ruby in cells treated with the Rho kinase inhibitor Y27632 at 60 min (E) and 150 min (F) after replating. In A–F, the upper images show a single xy confocal plane and the lower images show a single zx profile. The location of zx profiles is shown by dashed yellow lines on the xy images. Scale bars: 10 µm. (G) Temporal evolution of the apparent stiffness in control monolayers (black) and monolayers treated with SMIFH2 (green). (H) Temporal evolution of the apparent stiffness in control monolayers (black) and monolayers treated with Y27632 (purple) or blebbistatin (yellow). In G and H, the number of measurements for each condition is indicated below each box; boxes, median, 1st quartile and 3rd quartile; whiskers, maximum and minimum; dotted line, temporal evolution of monolayer apparent stiffness for each condition; *P<0.01 between control monolayers and treated monolayers at a given time-point (Student's t-test)

Mentions: After establishing a sufficiently broad contact, the branched dendritic network of actin is reorganised into a contractile actin belt through myosin contractility and formin-mediated polymerisation of linear F-actin arrays at intercellular junctions (Carramusa et al., 2007; Harris and Tepass, 2010; Kobielak et al., 2004; Tang and Brieher, 2012). Therefore, we investigated the contribution of formins by treatment with the broad spectrum inhibitor SMIFH2 (Rizvi et al., 2009), which has been shown to perturb junctional F-actin in MDCK monolayers (Tang and Brieher, 2012). Upon inhibition of formin activity, intercellular junctions appeared to form normally and some actin remodelling occurred (Fig. 6C,D) but the cells appeared more rounded than those under control conditions after 150 min (Fig. 6B,D). At all time-points, apparent stiffness was significantly lower than under control conditions (Fig. 6G). These results indicated that formin-mediated polymerisation of actin is required for the efficient establishment of monolayer stiffness.


Formation of adherens junctions leads to the emergence of a tissue-level tension in epithelial monolayers.

Harris AR, Daeden A, Charras GT - J. Cell. Sci. (2014)

Actin remodelling by formins and myosin is not required for initial junction formation but is necessary for the emergence of monolayer tissue tension. (A,B) Localisation of E-cadherin–GFP and LifeAct–Ruby in control cells at 60 min (A) and 150 min (B) after replating. (C,D) Localisation of E-cadherin–GFP and LifeAct–Ruby in cells treated with the broad-spectrum formin inhibitor SMIFH2 at 60 min (C) and 150 min (D) after replating. (E,F) Localisation of E-cadherin–GFP and LifeAct–Ruby in cells treated with the Rho kinase inhibitor Y27632 at 60 min (E) and 150 min (F) after replating. In A–F, the upper images show a single xy confocal plane and the lower images show a single zx profile. The location of zx profiles is shown by dashed yellow lines on the xy images. Scale bars: 10 µm. (G) Temporal evolution of the apparent stiffness in control monolayers (black) and monolayers treated with SMIFH2 (green). (H) Temporal evolution of the apparent stiffness in control monolayers (black) and monolayers treated with Y27632 (purple) or blebbistatin (yellow). In G and H, the number of measurements for each condition is indicated below each box; boxes, median, 1st quartile and 3rd quartile; whiskers, maximum and minimum; dotted line, temporal evolution of monolayer apparent stiffness for each condition; *P<0.01 between control monolayers and treated monolayers at a given time-point (Student's t-test)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043320&req=5

f06: Actin remodelling by formins and myosin is not required for initial junction formation but is necessary for the emergence of monolayer tissue tension. (A,B) Localisation of E-cadherin–GFP and LifeAct–Ruby in control cells at 60 min (A) and 150 min (B) after replating. (C,D) Localisation of E-cadherin–GFP and LifeAct–Ruby in cells treated with the broad-spectrum formin inhibitor SMIFH2 at 60 min (C) and 150 min (D) after replating. (E,F) Localisation of E-cadherin–GFP and LifeAct–Ruby in cells treated with the Rho kinase inhibitor Y27632 at 60 min (E) and 150 min (F) after replating. In A–F, the upper images show a single xy confocal plane and the lower images show a single zx profile. The location of zx profiles is shown by dashed yellow lines on the xy images. Scale bars: 10 µm. (G) Temporal evolution of the apparent stiffness in control monolayers (black) and monolayers treated with SMIFH2 (green). (H) Temporal evolution of the apparent stiffness in control monolayers (black) and monolayers treated with Y27632 (purple) or blebbistatin (yellow). In G and H, the number of measurements for each condition is indicated below each box; boxes, median, 1st quartile and 3rd quartile; whiskers, maximum and minimum; dotted line, temporal evolution of monolayer apparent stiffness for each condition; *P<0.01 between control monolayers and treated monolayers at a given time-point (Student's t-test)
Mentions: After establishing a sufficiently broad contact, the branched dendritic network of actin is reorganised into a contractile actin belt through myosin contractility and formin-mediated polymerisation of linear F-actin arrays at intercellular junctions (Carramusa et al., 2007; Harris and Tepass, 2010; Kobielak et al., 2004; Tang and Brieher, 2012). Therefore, we investigated the contribution of formins by treatment with the broad spectrum inhibitor SMIFH2 (Rizvi et al., 2009), which has been shown to perturb junctional F-actin in MDCK monolayers (Tang and Brieher, 2012). Upon inhibition of formin activity, intercellular junctions appeared to form normally and some actin remodelling occurred (Fig. 6C,D) but the cells appeared more rounded than those under control conditions after 150 min (Fig. 6B,D). At all time-points, apparent stiffness was significantly lower than under control conditions (Fig. 6G). These results indicated that formin-mediated polymerisation of actin is required for the efficient establishment of monolayer stiffness.

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.

View Article: PubMed Central - PubMed

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
Related in: MedlinePlus