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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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Mobility of E-cadherin puncta within the cell–cell contact interface. Fig. 9 shows a TIP scan of an entire contact during  a photobleach-recovery experiment. A newly developing plaque  in a 1.5-h-old contact was photobleached with a 2.8-μm-diameter  bleach circle (0 mins, 0 μm) on the TIP scan (arrow). Images  were collected every 16 s for 24 min at 0.11 μm/pixel. The fluorescence intensity scale bar ranges from 0–255 units divided into 15  colors.
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Figure 9: Mobility of E-cadherin puncta within the cell–cell contact interface. Fig. 9 shows a TIP scan of an entire contact during a photobleach-recovery experiment. A newly developing plaque in a 1.5-h-old contact was photobleached with a 2.8-μm-diameter bleach circle (0 mins, 0 μm) on the TIP scan (arrow). Images were collected every 16 s for 24 min at 0.11 μm/pixel. The fluorescence intensity scale bar ranges from 0–255 units divided into 15 colors.

Mentions: where r is the radius of the bleached region. Mobile fraction constants were calculated according to equation in Axelrod (1976; equation 9) at indicated times after recovery. Measurements of the slower photobleach recovery timecourses were subject to potential errors due to gradual redistribution motions of puncta and plaques during recovery phases. TIP scans of photobleach recoveries were generated (see Fig. 9) and used to reject data from any experiment where such errors might have been significant.


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)

Mobility of E-cadherin puncta within the cell–cell contact interface. Fig. 9 shows a TIP scan of an entire contact during  a photobleach-recovery experiment. A newly developing plaque  in a 1.5-h-old contact was photobleached with a 2.8-μm-diameter  bleach circle (0 mins, 0 μm) on the TIP scan (arrow). Images  were collected every 16 s for 24 min at 0.11 μm/pixel. The fluorescence intensity scale bar ranges from 0–255 units divided into 15  colors.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 9: Mobility of E-cadherin puncta within the cell–cell contact interface. Fig. 9 shows a TIP scan of an entire contact during a photobleach-recovery experiment. A newly developing plaque in a 1.5-h-old contact was photobleached with a 2.8-μm-diameter bleach circle (0 mins, 0 μm) on the TIP scan (arrow). Images were collected every 16 s for 24 min at 0.11 μm/pixel. The fluorescence intensity scale bar ranges from 0–255 units divided into 15 colors.
Mentions: where r is the radius of the bleached region. Mobile fraction constants were calculated according to equation in Axelrod (1976; equation 9) at indicated times after recovery. Measurements of the slower photobleach recovery timecourses were subject to potential errors due to gradual redistribution motions of puncta and plaques during recovery phases. TIP scans of photobleach recoveries were generated (see Fig. 9) and used to reject data from any experiment where such errors might have been significant.

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