title: The C-terminal domain of A1/Bfl-1 regulates its anti-inflammatory function in human endothelial cells.
abstract: A1/Bfl-1 is a NF-κB dependent, anti-apoptotic Bcl-2 family member that contains four Bcl-2 homology domains (BH) and an amphipathic C-terminal domain, and is expressed in endothelial cells (EC). Based on NF-κB reporter assays in bovine aortic EC, we have previously demonstrated that A1, like Bcl-2 and Bcl-xL, inhibits NF-κB activation. These results, however, do not fully translate when evaluating the cell's own NF-κB machinery in human EC overexpressing A1 by means of recombinant adenovirus (rAd.) mediated gene transfer. Indeed, overexpression of full-length A1 in human umbilical vein EC (HUVEC), and human dermal microvascular EC (HDMEC) failed to inhibit NF-κB activation. However, overexpression of a mutant lacking the C-terminal domain of A1 (A1ΔC) demonstrated a potent NF-κB inhibitory effect in these cells. Disparate effects of A1 and A1ΔC on NF-κB inhibition in human EC correlated with mitochondrial (A1) versus non-mitochondrial (A1ΔC) localization. In contrast, both full-length A1 and A1ΔC protected EC from staurosporine (STS)-induced cell death, indicating that mitochondrial localization was not necessary for A1's cytoprotective function in human EC. In conclusion, our data uncover a regulatory role for the C-terminal domain of A1 in human EC: anchoring A1 to the mitochondrion, which conserves but is not necessary for its cytoprotective function, or by its absence freeing A1 from the mitochondrion and uncovering an additional anti-inflammatory effect.
authors.affiliation: Department of Surgery, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Renata P
authors.initials: RP
authors.lastname: Guedes
authors.forename: Eduardo
authors.initials: E
authors.lastname: Rocha
authors.forename: Jerome
authors.initials: J
authors.lastname: Mahiou
authors.forename: Herwig P
authors.initials: HP
authors.lastname: Moll
authors.forename: Maria B
authors.initials: MB
authors.lastname: Arvelo
authors.forename: Janis M
authors.initials: JM
authors.lastname: Taube
authors.forename: Clayton R
authors.initials: CR
authors.lastname: Peterson
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Kaczmarek
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Longo
authors.forename: Cleide G
authors.initials: CG
authors.lastname: da Silva
authors.forename: Christiane
authors.initials: C
authors.lastname: Ferran
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000378:metabolism*; D017209:Apoptosis; D015153:Blotting, Western; D002417:Cattle; D049109:Cell Proliferation; D020405:Dermis / Q000166:cytology / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D015778:Minor Histocompatibility Antigens; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*
chemical_list: D000893:Anti-Inflammatory Agents; C096816:BCL2-related protein A1; D015778:Minor Histocompatibility Antigens; D016328:NF-kappa B; D019253:Proto-Oncogene Proteins c-bcl-2; D018799:Intercellular Adhesion Molecule-1; D008156:Luciferases