title: PECAM-1 modulates thrombin-induced tissue factor expression on endothelial cells.
abstract: Platelet endothelial cell adhesion molecule-1 (PECAM-1) (CD31) is known to inhibit platelet function and thrombus formation. The mechanisms involved in PECAM-1's roles as a modulator of hemostasis are still not completely understood. We examined the role of PECAM-1 as a regulator of tissue factor (TF) expression, a known important inducer of thrombosis. Wildtype and CD31KO mice underwent transient (30 min) renal ischemia followed by 24 h re-perfusion and their kidneys assessed for apoptosis, fibrin formation, and tissue factor expression. CD31KO mice exhibited increased tubular epithelial and endothelial apoptosis, increased fibrin deposition, and tissue factor expression. Human umbilical vein endothelial cells (HUVEC) transfected with antisense (AS) PECAM-1 oligonucleotides to downregulate PECAM-1 expression, exhibited greater induction of TF mRNA and protein expression as well as increased expression and nuclear localization of the transcription factor Egr-1 compared to scrambled AS PECAM-1 (Scr)-treated HUVEC following thrombin stimulation. TF induction was found to be mediated through thrombin receptor PAR-1 and the Galphai/o subunit of G-protein, confirmed by PAR-1 antagonist and pertussis toxin inhibition respectively. Thrombin-mediated TF induction was dependent on Rho Kinase activity, phosphorylation of p38(MAPK) and p85 & Akt dephosphorylation. The inverse correlation of PI3K-Akt phosphorylation with p38 (MAPK) phosphorylation was confirmed by pharmacological inhibition. These studies suggest that PECAM-1 is involved in regulating a signaling pathway, affecting PI3K and Akt activation, p38 (MAPK) phosphorylation, which in turn, affects Egr-1 expression and nuclear translocation, ultimately affecting TF expression. These findings provide new insights into the action of PECAM-1 as a modulator of thrombosis.
authors.affiliation: Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06520, USA.
authors.forename: Jenny J
authors.initials: JJ
authors.lastname: Zhang
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kelm
authors.forename: Purba
authors.initials: P
authors.lastname: Biswas
authors.forename: Michael
authors.initials: M
authors.lastname: Kashgarian
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Madri
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001777:Blood Coagulation / Q000502:physiology*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics; D051766:Early Growth Response Protein 1 / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005337:Fibrin / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D044463:Receptor, PAR-1 / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology; D013917:Thrombin / Q000378:metabolism* / Q000494:pharmacology; D013925:Thromboplastin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013927:Thrombosis / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D020319:Oligodeoxyribonucleotides, Antisense; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D012333:RNA, Messenger; D044463:Receptor, PAR-1; D005337:Fibrin; D013925:Thromboplastin; D013917:Thrombin