title: Increased endothelial cell permeability in endoglin-deficient cells.
abstract: Endoglin (ENG) is a TGF-β superfamily coreceptor essential for vascular endothelium integrity. ENG mutations lead to a vascular dysplasia associated with frequent hemorrhages in multiple organs, whereas ENG null mouse embryos die at midgestation with impaired heart development and leaky vasculature. ENG interacts with several proteins involved in cell adhesion, and we postulated that it regulates vascular permeability. The current study assessed the permeability of ENG homozygous null (Eng(-/-)), heterozygous (Eng(+/-)), and normal (Eng(+/+)) mouse embryonic endothelial cell (EC) lines. Permeability, measured by passage of fluorescent dextran through EC monolayers, was increased 2.9- and 1.7-fold for Eng(-/-) and Eng(+/-) ECs, respectively, compared to control ECs and was not increased by TGF-β1 or VEGF. Prolonged starvation increased Eng(-/-) EC permeability by 3.7-fold with no effect on control ECs; neutrophils transmigrated faster through Eng(-/-) than Eng(+/+) monolayers. Using a pull-down assay, we demonstrate that Ras homolog gene family (Rho) A is constitutively active in Eng(-/-) and Eng(+/-) ECs. We show that the endothelial barrier destabilizing factor thrombospondin-1 and its receptor-like protein tyrosine phosphatase are increased, whereas stabilizing factors VEGF receptor 2, vascular endothelial-cadherin, p21-activated kinase, and Ras-related C3 botulinum toxin substrate 2 are decreased in Eng(-/-) cells. Our findings indicate that ENG deficiency leads to EC hyperpermeability through constitutive activation of RhoA and destabilization of endothelial barrier function.
authors.affiliation: *Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Immunology and Keenan Research Centre for Biomedical Science, Anesthesia Research, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada jerkicm@smh.ca.
authors.forename: Mirjana
authors.initials: M
authors.lastname: Jerkic
authors.affiliation: *Molecular Structure and Function Program, The Hospital for Sick Children, Toronto, Ontario, Canada; and Department of Immunology and Keenan Research Centre for Biomedical Science, Anesthesia Research, St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: Letarte
mesh_terms: D000818:Animals; D002199:Capillary Permeability; D002460:Cell Line; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism*; D000071063:Endoglin; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000172:deficiency* / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D019700:Thrombospondin 1 / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein
chemical_list: D000071063:Endoglin; C502004:Eng protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; C508961:Tgfb1 protein, mouse; D019700:Thrombospondin 1; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C000592875:Kdr protein, mouse; D040301:Vascular Endothelial Growth Factor Receptor-2; C526380:RhoA protein, mouse; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein
keywords: RhoA; TGF-β1; TSP-1; VEGF