Title : Distribution of sialic acids and junctional cell adhesion molecules in endothelial cells in situ and in culture
Abstract :
- Based on the glycosylation data described above, the localization of sialic acids and Ca2 +-dependent VE-cadherin was studied in endothelial cells of the human umbilical vein and arteries in situ as well as in culture (Figures 6, 7)
- As a control, Ca2 +-independent PECAM-1 was also localized (Figure 8)
- Digoxigenin labeled MAA- and SNA-lectins, used together or individually (MAA binds to α2,3-linked and SNA binds to α2,6-linked sialic acids), stained the intercellular junctions as well as surface proteins of endothelial cells in situ (Figure 6) and in culture (Figures 7, 8)
- Sialic acids, found at interendothelial junctions, largely colocalized with VE-cadherin in a not interrupted continuous pattern in endothelial cells of human umbilical vein and arteries in situ (Figure 6) and in culture (Figure 7)
- In addition, at overlapping junctional areas of adjacent highly confluent endothelial cells a netlike distribution of VE-cadherin was observed (Figure 7A,B,D,E) that, again, largely colocalized with MAA/SNA-staining (Figure 7B1,D1,E1)
- This netlike structure has not been described before and represents a highly ordered VE-cadherin organization only observable in confluent endothelial cell cultures
- Therefore, we termed it VE-cadherin superstructure
- Double labeling of VE-cadherin and catenins also displayed a codistribution of this highly organized structure (not shown)
- PECAM-1 , labeled with a monoclonal antibody, partially colo-calized with MAA/SNA but to a lesser extent than VE-cadherin (Figure 8C,D)
- This was further confirmed by serial optical z-sections using confocal laser microscopy
- Whereas sialic acids and VE-cadherin were primarily localized within the apical area of intercellular junctions, PECAM-1 appears to reside predominantly at the basal side (data not shown)
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