title: CD44 regulation of endothelial cell proliferation and apoptosis via modulation of CD31 and VE-cadherin expression.
abstract: CD44 has been implicated in a diverse array of cell behaviors and in a diverse range of signaling pathway activations under physiological and pathophysiological conditions. We have documented a role for CD44 in mediating vascular barrier integrity via regulation of PECAM-1 (CD31) expression. We now report our findings on the roles of CD44 in modulating proliferation and apoptosis of microvascular endothelial cells via its modulation of CD31 and VE-cadherin expression and the Hippo pathway. In this report, we demonstrate persistent increased proliferation and reduced activations of both effector and initiator caspases in high cell density, postconfluent CD44 knock-out (CD44KO), and CD31KO cultures. We found that reconstitution with murine CD44 or CD31 restored the proliferative and caspase activation rates to WT levels. Moreover, we have confirmed that the CD31 ecto-domain plays a key role in specific caspase cascades as well as cell adhesion-mediated cell growth and found that CD31 deficiency results in a reduction in VE-cadherin expression. Last, we have shown that both CD44KO and CD31KO endothelial cells exhibit a reduced VE-cadherin expression correlating with increased survivin expression and YAP nuclear localization, consistent with inactivation of the Hippo pathway, resulting in increased proliferation and decreased apoptosis. These findings support the concept that CD44 mediates several of its effects on endothelia through modulation of adhesion protein expression, which, in addition to its known modulation of junctional integrity, matrix metalloproteinase levels and activation, interactions with cortical membrane proteins, and selected signaling pathways, plays a key role as a critical regulator of vascular function.
authors.affiliation: From the Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Tsuneki
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Madri
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis*; D017209:Apoptosis / Q000502:physiology*; D015820:Cadherins / Q000096:biosynthesis*; D002448:Cell Adhesion / Q000502:physiology; D049109:Cell Proliferation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D000090683:Hippo Signaling Pathway; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism*; D051034:Inhibitor of Apoptosis Proteins / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000096:biosynthesis / Q000235:genetics; D000077022:Survivin; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015820:Cadherins; D018960:Hyaluronan Receptors; D051034:Inhibitor of Apoptosis Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D017346:Protein Serine-Threonine Kinases; D012097:Repressor Proteins; D000077022:Survivin; D000099152:Cadherin 5; C117749:Birc5 protein, mouse; C476399:Cd44 protein, mouse
keywords: Apoptosis; Caspase; Cd31; Cd44; Cell Proliferation; Endothelial Cell; Survivin; Vascular Biology; Western Blotting