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Mechanisms of epithelial cell-cell adhesion and cell compaction revealed by high-resolution tracking of E-cadherin-green fluorescent protein.

Adams CL, Chen YT, Smith SJ, Nelson WJ - J. Cell Biol. (1998)

Bottom Line: This reorganization results in the formation of a circumferential actin cable that circumscribes both cells, and is embedded into each E-cadherin plaque at the contact margin.The reorganization of E-cadherin and actin results in the condensation of cells into colonies.We propose a model to explain how, through strengthening and compaction, E-cadherin and actin cables coordinate to remodel initial cell-cell contacts to the final condensation of cells into colonies.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305-5345, USA.

ABSTRACT
Cadherin-mediated adhesion initiates cell reorganization into tissues, but the mechanisms and dynamics of such adhesion are poorly understood. Using time-lapse imaging and photobleach recovery analyses of a fully functional E-cadherin/GFP fusion protein, we define three sequential stages in cell-cell adhesion and provide evidence for mechanisms involving E-cadherin and the actin cytoskeleton in transitions between these stages. In the first stage, membrane contacts between two cells initiate coalescence of a highly mobile, diffuse pool of cell surface E-cadherin into immobile punctate aggregates along contacting membranes. These E-cadherin aggregates are spatially coincident with membrane attachment sites for actin filaments branching off from circumferential actin cables that circumscribe each cell. In the second stage, circumferential actin cables near cell-cell contact sites separate, and the resulting two ends of the cable swing outwards to the perimeter of the contact. Concomitantly, subsets of E-cadherin puncta are also swept to the margins of the contact where they coalesce into large E-cadherin plaques. This reorganization results in the formation of a circumferential actin cable that circumscribes both cells, and is embedded into each E-cadherin plaque at the contact margin. At this stage, the two cells achieve maximum contact, a process referred to as compaction. These changes in E-cadherin and actin distributions are repeated when additional single cells adhere to large groups of cells. The third stage of adhesion occurs as additional cells are added to groups of >3 cells; circumferential actin cables linked to E-cadherin plaques on adjacent cells appear to constrict in a purse-string action, resulting in the further coalescence of individual plaques into the vertices of multicell contacts. The reorganization of E-cadherin and actin results in the condensation of cells into colonies. We propose a model to explain how, through strengthening and compaction, E-cadherin and actin cables coordinate to remodel initial cell-cell contacts to the final condensation of cells into colonies.

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Distribution of EcadGFP during monolayer formation.  A single confocal image was collected from EcadGFP expressing  cells every 10 min for 12 h at 0.12 μm/pixel at 12 sites. Five representative images from each time-lapse are shown. Elapsed time is  indicated on top of each column in h (0, 2, 4, 6, and 8, respectively). The circles in A highlight the edges of a cell–cell contact  that have developed large aggregates of EcadGFP plaques. The  arrows in B–F, columns 0 or 2 h point to the well-separated  plaques at the edges of developing cell–cell contacts that reorganize into a multicellular vertex by 8 h. Note that the 0-h designation is arbitrarily set as the first time point shown. Bar, 15 μm.
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Figure 2: Distribution of EcadGFP during monolayer formation. A single confocal image was collected from EcadGFP expressing cells every 10 min for 12 h at 0.12 μm/pixel at 12 sites. Five representative images from each time-lapse are shown. Elapsed time is indicated on top of each column in h (0, 2, 4, 6, and 8, respectively). The circles in A highlight the edges of a cell–cell contact that have developed large aggregates of EcadGFP plaques. The arrows in B–F, columns 0 or 2 h point to the well-separated plaques at the edges of developing cell–cell contacts that reorganize into a multicellular vertex by 8 h. Note that the 0-h designation is arbitrarily set as the first time point shown. Bar, 15 μm.

Mentions: EcadGFP expressing MDCK cells were imaged for 10 h to observe the dynamics of the localization of EcadGFP during formation of contacts between single cells, and during formation of small multicell colonies (Fig. 2). Expression of EcadGFP in single cells was relatively uniform over the plasma membrane with some increased intensity in a circumferential ring at the cell periphery (Fig. 2, A and B, 0 h). During the formation of cell–cell contacts between two (Fig. 2 A) or three (Fig. 2 B) cells, or single cells and larger cell clusters (Fig. 2 C), EcadGFP fluorescence became significantly more intense at the cell–cell contact during the first 2 h. After at least 2 h, the largest and brightest regions of EcadGFP fluorescence were at the edges of cell–cell contacts; we call these structures plaques (Fig. 2, circles). The fluorescence intensity of EcadGFP plaques was 6–10 times greater than that of EcadGFP in noncontacting membranes, and 2–4 times greater than that of EcadGFP in areas of the membrane in the middle of the contact (Fig. 2, A–C; 8 h).


Mechanisms of epithelial cell-cell adhesion and cell compaction revealed by high-resolution tracking of E-cadherin-green fluorescent protein.

Adams CL, Chen YT, Smith SJ, Nelson WJ - J. Cell Biol. (1998)

Distribution of EcadGFP during monolayer formation.  A single confocal image was collected from EcadGFP expressing  cells every 10 min for 12 h at 0.12 μm/pixel at 12 sites. Five representative images from each time-lapse are shown. Elapsed time is  indicated on top of each column in h (0, 2, 4, 6, and 8, respectively). The circles in A highlight the edges of a cell–cell contact  that have developed large aggregates of EcadGFP plaques. The  arrows in B–F, columns 0 or 2 h point to the well-separated  plaques at the edges of developing cell–cell contacts that reorganize into a multicellular vertex by 8 h. Note that the 0-h designation is arbitrarily set as the first time point shown. Bar, 15 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2132880&req=5

Figure 2: Distribution of EcadGFP during monolayer formation. A single confocal image was collected from EcadGFP expressing cells every 10 min for 12 h at 0.12 μm/pixel at 12 sites. Five representative images from each time-lapse are shown. Elapsed time is indicated on top of each column in h (0, 2, 4, 6, and 8, respectively). The circles in A highlight the edges of a cell–cell contact that have developed large aggregates of EcadGFP plaques. The arrows in B–F, columns 0 or 2 h point to the well-separated plaques at the edges of developing cell–cell contacts that reorganize into a multicellular vertex by 8 h. Note that the 0-h designation is arbitrarily set as the first time point shown. Bar, 15 μm.
Mentions: EcadGFP expressing MDCK cells were imaged for 10 h to observe the dynamics of the localization of EcadGFP during formation of contacts between single cells, and during formation of small multicell colonies (Fig. 2). Expression of EcadGFP in single cells was relatively uniform over the plasma membrane with some increased intensity in a circumferential ring at the cell periphery (Fig. 2, A and B, 0 h). During the formation of cell–cell contacts between two (Fig. 2 A) or three (Fig. 2 B) cells, or single cells and larger cell clusters (Fig. 2 C), EcadGFP fluorescence became significantly more intense at the cell–cell contact during the first 2 h. After at least 2 h, the largest and brightest regions of EcadGFP fluorescence were at the edges of cell–cell contacts; we call these structures plaques (Fig. 2, circles). The fluorescence intensity of EcadGFP plaques was 6–10 times greater than that of EcadGFP in noncontacting membranes, and 2–4 times greater than that of EcadGFP in areas of the membrane in the middle of the contact (Fig. 2, A–C; 8 h).

Bottom Line: This reorganization results in the formation of a circumferential actin cable that circumscribes both cells, and is embedded into each E-cadherin plaque at the contact margin.The reorganization of E-cadherin and actin results in the condensation of cells into colonies.We propose a model to explain how, through strengthening and compaction, E-cadherin and actin cables coordinate to remodel initial cell-cell contacts to the final condensation of cells into colonies.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California 94305-5345, USA.

ABSTRACT
Cadherin-mediated adhesion initiates cell reorganization into tissues, but the mechanisms and dynamics of such adhesion are poorly understood. Using time-lapse imaging and photobleach recovery analyses of a fully functional E-cadherin/GFP fusion protein, we define three sequential stages in cell-cell adhesion and provide evidence for mechanisms involving E-cadherin and the actin cytoskeleton in transitions between these stages. In the first stage, membrane contacts between two cells initiate coalescence of a highly mobile, diffuse pool of cell surface E-cadherin into immobile punctate aggregates along contacting membranes. These E-cadherin aggregates are spatially coincident with membrane attachment sites for actin filaments branching off from circumferential actin cables that circumscribe each cell. In the second stage, circumferential actin cables near cell-cell contact sites separate, and the resulting two ends of the cable swing outwards to the perimeter of the contact. Concomitantly, subsets of E-cadherin puncta are also swept to the margins of the contact where they coalesce into large E-cadherin plaques. This reorganization results in the formation of a circumferential actin cable that circumscribes both cells, and is embedded into each E-cadherin plaque at the contact margin. At this stage, the two cells achieve maximum contact, a process referred to as compaction. These changes in E-cadherin and actin distributions are repeated when additional single cells adhere to large groups of cells. The third stage of adhesion occurs as additional cells are added to groups of >3 cells; circumferential actin cables linked to E-cadherin plaques on adjacent cells appear to constrict in a purse-string action, resulting in the further coalescence of individual plaques into the vertices of multicell contacts. The reorganization of E-cadherin and actin results in the condensation of cells into colonies. We propose a model to explain how, through strengthening and compaction, E-cadherin and actin cables coordinate to remodel initial cell-cell contacts to the final condensation of cells into colonies.

Show MeSH
Related in: MedlinePlus