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Recycling of E-cadherin: a potential mechanism for regulating cadherin dynamics.

Le TL, Yap AS, Stow JL - J. Cell Biol. (1999)

Bottom Line: The reformation of cell junctions after replacement of Ca2+ was then found to be inhibited when recycling of endocytosed E-cadherin was disrupted by bafilomycin treatment.The endocytosis and recycling of E-cadherin and of the transferrin receptor were similarly inhibited by potassium depletion and by bafilomycin treatment, and both proteins were accumulated in intracellular compartments by an 18 degrees C temperature block, suggesting that endocytosis may occur via a clathrin-mediated pathway.We conclude that a pool of surface E-cadherin is constantly trafficked through an endocytic, recycling pathway and that this may provide a mechanism for regulating the availability of E-cadherin for junction formation in development, tissue remodeling, and tumorigenesis.

View Article: PubMed Central - PubMed

Affiliation: Centre for Molecular and Cellular Biology, The University of Queensland, Brisbane, 4072 Queensland, Australia.

ABSTRACT
E-Cadherin plays critical roles in many aspects of cell adhesion, epithelial development, and the establishment and maintenance of epithelial polarity. The fate of E-cadherin once it is delivered to the basolateral cell surface, and the mechanisms which govern its participation in adherens junctions, are not well understood. Using surface biotinylation and recycling assays, we observed that some of the cell surface E-cadherin is actively internalized and is then recycled back to the plasma membrane. The pool of E-cadherin undergoing endocytosis and recycling was markedly increased in cells without stable cell-cell contacts, i.e., in preconfluent cells and after cell contacts were disrupted by depletion of extracellular Ca2+, suggesting that endocytic trafficking of E-cadherin is regulated by cell-cell contact. The reformation of cell junctions after replacement of Ca2+ was then found to be inhibited when recycling of endocytosed E-cadherin was disrupted by bafilomycin treatment. The endocytosis and recycling of E-cadherin and of the transferrin receptor were similarly inhibited by potassium depletion and by bafilomycin treatment, and both proteins were accumulated in intracellular compartments by an 18 degrees C temperature block, suggesting that endocytosis may occur via a clathrin-mediated pathway. We conclude that a pool of surface E-cadherin is constantly trafficked through an endocytic, recycling pathway and that this may provide a mechanism for regulating the availability of E-cadherin for junction formation in development, tissue remodeling, and tumorigenesis.

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Double labeling of E-cadherin and rab proteins. MDCK cells were incubated at 18°C, fixed, and double labeled by immunofluorescence with antibodies to E-cadherin (b and d) and rab 5 (a) or E-cadherin and rab 7 (c). Vesicular staining of rab 5 (a) is consistent with its presence on early endosomes. E-Cadherin is colocalized with rab 5 in some endosomes (a and b). Punctate staining of rab 7 on late endosomes in the perinuclear area (c) did not coincide with any of the vesicles labeled for E-cadherin (d). Representative fields of cells were photographed.
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Figure 10: Double labeling of E-cadherin and rab proteins. MDCK cells were incubated at 18°C, fixed, and double labeled by immunofluorescence with antibodies to E-cadherin (b and d) and rab 5 (a) or E-cadherin and rab 7 (c). Vesicular staining of rab 5 (a) is consistent with its presence on early endosomes. E-Cadherin is colocalized with rab 5 in some endosomes (a and b). Punctate staining of rab 7 on late endosomes in the perinuclear area (c) did not coincide with any of the vesicles labeled for E-cadherin (d). Representative fields of cells were photographed.

Mentions: Double labeling was also carried out by immunofluorescence staining to colocalize internalized E-cadherin with known markers of compartments in clathrin-mediated pathways. Confluent cell monolayers were temperature-blocked at 18°C in order to accumulate intracellular E-cadherin. In cells at 18°C, internalized E-cadherin was colocalized in some, but not all, vesicles stained for the early endosomal marker, rab 5 (Fig. 10, a and b). In contrast, internalized E-cadherin did not colocalize with the late endosomal protein, rab 7 (Fig. 10c and Fig. d). The vesicular staining pattern of E-cadherin and its partial overlap with rab 5 shows that at 18°C endocytosed E-cadherin accumulates in early endosomal or recycling compartments. The lack of colocalization with rab 7 in late endosomes is further evidence that this pool of endocytosed E-cadherin is not destined for lysosomal degradation.


Recycling of E-cadherin: a potential mechanism for regulating cadherin dynamics.

Le TL, Yap AS, Stow JL - J. Cell Biol. (1999)

Double labeling of E-cadherin and rab proteins. MDCK cells were incubated at 18°C, fixed, and double labeled by immunofluorescence with antibodies to E-cadherin (b and d) and rab 5 (a) or E-cadherin and rab 7 (c). Vesicular staining of rab 5 (a) is consistent with its presence on early endosomes. E-Cadherin is colocalized with rab 5 in some endosomes (a and b). Punctate staining of rab 7 on late endosomes in the perinuclear area (c) did not coincide with any of the vesicles labeled for E-cadherin (d). Representative fields of cells were photographed.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199726&req=5

Figure 10: Double labeling of E-cadherin and rab proteins. MDCK cells were incubated at 18°C, fixed, and double labeled by immunofluorescence with antibodies to E-cadherin (b and d) and rab 5 (a) or E-cadherin and rab 7 (c). Vesicular staining of rab 5 (a) is consistent with its presence on early endosomes. E-Cadherin is colocalized with rab 5 in some endosomes (a and b). Punctate staining of rab 7 on late endosomes in the perinuclear area (c) did not coincide with any of the vesicles labeled for E-cadherin (d). Representative fields of cells were photographed.
Mentions: Double labeling was also carried out by immunofluorescence staining to colocalize internalized E-cadherin with known markers of compartments in clathrin-mediated pathways. Confluent cell monolayers were temperature-blocked at 18°C in order to accumulate intracellular E-cadherin. In cells at 18°C, internalized E-cadherin was colocalized in some, but not all, vesicles stained for the early endosomal marker, rab 5 (Fig. 10, a and b). In contrast, internalized E-cadherin did not colocalize with the late endosomal protein, rab 7 (Fig. 10c and Fig. d). The vesicular staining pattern of E-cadherin and its partial overlap with rab 5 shows that at 18°C endocytosed E-cadherin accumulates in early endosomal or recycling compartments. The lack of colocalization with rab 7 in late endosomes is further evidence that this pool of endocytosed E-cadherin is not destined for lysosomal degradation.

Bottom Line: The reformation of cell junctions after replacement of Ca2+ was then found to be inhibited when recycling of endocytosed E-cadherin was disrupted by bafilomycin treatment.The endocytosis and recycling of E-cadherin and of the transferrin receptor were similarly inhibited by potassium depletion and by bafilomycin treatment, and both proteins were accumulated in intracellular compartments by an 18 degrees C temperature block, suggesting that endocytosis may occur via a clathrin-mediated pathway.We conclude that a pool of surface E-cadherin is constantly trafficked through an endocytic, recycling pathway and that this may provide a mechanism for regulating the availability of E-cadherin for junction formation in development, tissue remodeling, and tumorigenesis.

View Article: PubMed Central - PubMed

Affiliation: Centre for Molecular and Cellular Biology, The University of Queensland, Brisbane, 4072 Queensland, Australia.

ABSTRACT
E-Cadherin plays critical roles in many aspects of cell adhesion, epithelial development, and the establishment and maintenance of epithelial polarity. The fate of E-cadherin once it is delivered to the basolateral cell surface, and the mechanisms which govern its participation in adherens junctions, are not well understood. Using surface biotinylation and recycling assays, we observed that some of the cell surface E-cadherin is actively internalized and is then recycled back to the plasma membrane. The pool of E-cadherin undergoing endocytosis and recycling was markedly increased in cells without stable cell-cell contacts, i.e., in preconfluent cells and after cell contacts were disrupted by depletion of extracellular Ca2+, suggesting that endocytic trafficking of E-cadherin is regulated by cell-cell contact. The reformation of cell junctions after replacement of Ca2+ was then found to be inhibited when recycling of endocytosed E-cadherin was disrupted by bafilomycin treatment. The endocytosis and recycling of E-cadherin and of the transferrin receptor were similarly inhibited by potassium depletion and by bafilomycin treatment, and both proteins were accumulated in intracellular compartments by an 18 degrees C temperature block, suggesting that endocytosis may occur via a clathrin-mediated pathway. We conclude that a pool of surface E-cadherin is constantly trafficked through an endocytic, recycling pathway and that this may provide a mechanism for regulating the availability of E-cadherin for junction formation in development, tissue remodeling, and tumorigenesis.

Show MeSH
Related in: MedlinePlus