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The conditional inactivation of the beta-catenin gene in endothelial cells causes a defective vascular pattern and increased vascular fragility.

Cattelino A, Liebner S, Gallini R, Zanetti A, Balconi G, Corsi A, Bianco P, Wolburg H, Moore R, Oreda B, Kemler R, Dejana E - J. Cell Biol. (2003)

Bottom Line: We found that early phases of vasculogenesis and angiogenesis were not affected in mutant embryos; however, vascular patterning in the head, vitelline, umbilical vessels, and the placenta was altered.These changes paralleled a decrease in cell-cell adhesion strength and an increase in paracellular permeability.We conclude that in vivo, the absence of beta-catenin significantly reduces the capacity of endothelial cells to maintain intercellular contacts.

View Article: PubMed Central - PubMed

Affiliation: FIRC Institute of Molecular Oncology, 16-20139, Milan, Italy.

ABSTRACT
Using the Cre/loxP system we conditionally inactivated beta-catenin in endothelial cells. We found that early phases of vasculogenesis and angiogenesis were not affected in mutant embryos; however, vascular patterning in the head, vitelline, umbilical vessels, and the placenta was altered. In addition, in many regions, the vascular lumen was irregular with the formation of lacunae at bifurcations, vessels were frequently hemorrhagic, and fluid extravasation in the pericardial cavity was observed. Cultured beta-catenin -/- endothelial cells showed a different organization of intercellular junctions with a decrease in alpha-catenin in favor of desmoplakin and marked changes in actin cytoskeleton. These changes paralleled a decrease in cell-cell adhesion strength and an increase in paracellular permeability. We conclude that in vivo, the absence of beta-catenin significantly reduces the capacity of endothelial cells to maintain intercellular contacts. This may become more marked when the vessels are exposed to high or turbulent flow, such as at bifurcations or in the beating heart, leading to fluid leakage or hemorrhages.

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Cell–cell adhesion strength in control and mutant endothelial cells. (A–C) Analysis of endothelial cell migration into a wound. Crystal violet staining of control (A) and β-catenin −/− (B) endothelial cells 8 h after mechanical wounding of the monolayer. C reports the number of migrating single cells into the wound at 8 h. (D) Permeability across endothelial cell monolayers. β-Catenin −/− confluent endothelial cells show a higher passage of FITC-dextran as compared with the control cells. In C and D, columns represent means ± SEM of quadruplicates of a typical experiments out of three performed. (E–H) β-catenin– endothelial cells (−/−) form only small, disorganized aggregates interconnected with thin, single-cell elongations on Matrigel™ matrix (G and H), whereas control endothelial cells are able to organize into aggregates and bundles and show a typical cordlike structure on Matrigel™ matrix (E and F).
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fig10: Cell–cell adhesion strength in control and mutant endothelial cells. (A–C) Analysis of endothelial cell migration into a wound. Crystal violet staining of control (A) and β-catenin −/− (B) endothelial cells 8 h after mechanical wounding of the monolayer. C reports the number of migrating single cells into the wound at 8 h. (D) Permeability across endothelial cell monolayers. β-Catenin −/− confluent endothelial cells show a higher passage of FITC-dextran as compared with the control cells. In C and D, columns represent means ± SEM of quadruplicates of a typical experiments out of three performed. (E–H) β-catenin– endothelial cells (−/−) form only small, disorganized aggregates interconnected with thin, single-cell elongations on Matrigel™ matrix (G and H), whereas control endothelial cells are able to organize into aggregates and bundles and show a typical cordlike structure on Matrigel™ matrix (E and F).

Mentions: When intercellular junctions are affected, cells tend to detach from the monolayer and migrate as single cells (Corada et al., 2002). As reported in Fig. 10 (A–C), single migrating cells were very few in control monolayers, whereas cells lacking β-catenin detached from the monolayer and migrated into the wound much more efficiently. Differences in cell migration velocity or cell proliferation at the cell front among β-catenin +/+ and −/− cells were excluded by the phagokinetic track assay and BrdU incorporation respectively (see supplemental Materials and methods section, Fig. S5; available at http://www.jcb.org/cgi/content/full/jcb.200212157/DC1).


The conditional inactivation of the beta-catenin gene in endothelial cells causes a defective vascular pattern and increased vascular fragility.

Cattelino A, Liebner S, Gallini R, Zanetti A, Balconi G, Corsi A, Bianco P, Wolburg H, Moore R, Oreda B, Kemler R, Dejana E - J. Cell Biol. (2003)

Cell–cell adhesion strength in control and mutant endothelial cells. (A–C) Analysis of endothelial cell migration into a wound. Crystal violet staining of control (A) and β-catenin −/− (B) endothelial cells 8 h after mechanical wounding of the monolayer. C reports the number of migrating single cells into the wound at 8 h. (D) Permeability across endothelial cell monolayers. β-Catenin −/− confluent endothelial cells show a higher passage of FITC-dextran as compared with the control cells. In C and D, columns represent means ± SEM of quadruplicates of a typical experiments out of three performed. (E–H) β-catenin– endothelial cells (−/−) form only small, disorganized aggregates interconnected with thin, single-cell elongations on Matrigel™ matrix (G and H), whereas control endothelial cells are able to organize into aggregates and bundles and show a typical cordlike structure on Matrigel™ matrix (E and F).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172846&req=5

fig10: Cell–cell adhesion strength in control and mutant endothelial cells. (A–C) Analysis of endothelial cell migration into a wound. Crystal violet staining of control (A) and β-catenin −/− (B) endothelial cells 8 h after mechanical wounding of the monolayer. C reports the number of migrating single cells into the wound at 8 h. (D) Permeability across endothelial cell monolayers. β-Catenin −/− confluent endothelial cells show a higher passage of FITC-dextran as compared with the control cells. In C and D, columns represent means ± SEM of quadruplicates of a typical experiments out of three performed. (E–H) β-catenin– endothelial cells (−/−) form only small, disorganized aggregates interconnected with thin, single-cell elongations on Matrigel™ matrix (G and H), whereas control endothelial cells are able to organize into aggregates and bundles and show a typical cordlike structure on Matrigel™ matrix (E and F).
Mentions: When intercellular junctions are affected, cells tend to detach from the monolayer and migrate as single cells (Corada et al., 2002). As reported in Fig. 10 (A–C), single migrating cells were very few in control monolayers, whereas cells lacking β-catenin detached from the monolayer and migrated into the wound much more efficiently. Differences in cell migration velocity or cell proliferation at the cell front among β-catenin +/+ and −/− cells were excluded by the phagokinetic track assay and BrdU incorporation respectively (see supplemental Materials and methods section, Fig. S5; available at http://www.jcb.org/cgi/content/full/jcb.200212157/DC1).

Bottom Line: We found that early phases of vasculogenesis and angiogenesis were not affected in mutant embryos; however, vascular patterning in the head, vitelline, umbilical vessels, and the placenta was altered.These changes paralleled a decrease in cell-cell adhesion strength and an increase in paracellular permeability.We conclude that in vivo, the absence of beta-catenin significantly reduces the capacity of endothelial cells to maintain intercellular contacts.

View Article: PubMed Central - PubMed

Affiliation: FIRC Institute of Molecular Oncology, 16-20139, Milan, Italy.

ABSTRACT
Using the Cre/loxP system we conditionally inactivated beta-catenin in endothelial cells. We found that early phases of vasculogenesis and angiogenesis were not affected in mutant embryos; however, vascular patterning in the head, vitelline, umbilical vessels, and the placenta was altered. In addition, in many regions, the vascular lumen was irregular with the formation of lacunae at bifurcations, vessels were frequently hemorrhagic, and fluid extravasation in the pericardial cavity was observed. Cultured beta-catenin -/- endothelial cells showed a different organization of intercellular junctions with a decrease in alpha-catenin in favor of desmoplakin and marked changes in actin cytoskeleton. These changes paralleled a decrease in cell-cell adhesion strength and an increase in paracellular permeability. We conclude that in vivo, the absence of beta-catenin significantly reduces the capacity of endothelial cells to maintain intercellular contacts. This may become more marked when the vessels are exposed to high or turbulent flow, such as at bifurcations or in the beating heart, leading to fluid leakage or hemorrhages.

Show MeSH
Related in: MedlinePlus