title: Protective cross talk between activated protein C and TNF signaling in vascular endothelial cells: implication of EPCR, noncanonical NF-κB, and ERK1/2 MAP kinases.
abstract: Activated protein C (APC) is a natural anticoagulant protease that displays cytoprotective and antiinflammatory activities and has been demonstrated to reduce mortality of patients with severe sepsis. However, APC signaling is not fully understood. This study further investigated the antiinflammatory effects of APC in vascular endothelial cells (EC) and examined the cross talk between APC and TNF signaling. Analysis of the regulatory mechanisms mediated by APC on vascular human EC shows that APC impairs TNF signaling by triggering a preemptive activation of intracellular pathways. We found that APC signaling causes a moderate but significant induction of cell adhesion molecules (CAMs) including VCAM-1 at mRNA and protein levels. Activation of the noncanonical NF-κB and ERK1/2 are both pivotal to APC signaling leading to VCAM-1 expression. APC upregulates TNF receptor-associated factor 2 (TRAF2) and phosphorylates NF-κB p65 at Ser276 and Ser536 independently of IκB degradation. The ultimate protective antiinflammatory effect of APC in response to TNF is associated with a sustained activation of ERK1/2 and Akt while phosphorylation of NF-κB p65 is precluded. Inhibitors of ERK (PD98059 and U0126) abolish the antiinflammatory signal mediated by APC. Blocking antibodies and silencing assays also suggest that, in EC, protease-activated receptor 1 and endothelial protein C receptor (EPCR) both conduct ERK activation and VCAM-1 induction in response to APC. To conclude, APC protects EC by attenuating CAM expression during inflammation. APC engages a regulatory cross talk involving EPCR, ERK, and NF-κB that impairs TNF signaling.
authors.affiliation: Institut national de la santé et de la recherche médicale, Nantes, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Guitton
authors.forename: Alice
authors.initials: A
authors.lastname: Cottereau
authors.forename: Nathalie
authors.initials: N
authors.lastname: Gérard
authors.forename: Thibaut
authors.initials: T
authors.lastname: Quillard
authors.forename: Annabelle
authors.initials: A
authors.lastname: Chauveau
authors.forename: Julie
authors.initials: J
authors.lastname: Devallière
authors.forename: Pierre
authors.initials: P
authors.lastname: Tonnerre
authors.forename: Béatrice
authors.initials: B
authors.lastname: Charreau
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D019040:E-Selectin / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology*; D000074283:Endothelial Protein C Receptor; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D011486:Protein C / Q000378:metabolism*; D044463:Receptor, PAR-1 / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism
chemical_list: D015703:Antigens, CD; D019040:E-Selectin; D000074283:Endothelial Protein C Receptor; D016328:NF-kappa B; C478370:PROCR protein, human; D011486:Protein C; D044463:Receptor, PAR-1; D011956:Receptors, Cell Surface; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3