title: Elevated level of fibrinogen increases caveolae formation; role of matrix metalloproteinase-9.
abstract: The role of the inflammatory agent fibrinogen (Fg) in increased pial venular permeability has been shown previously. It was suggested that an activation of matrix metalloproteinase-9 (MMP-9) is involved in Fg-induced enhanced transcytosis through endothelial cells (ECs). However, direct link between Fg, caveolae formation, and MMP-9 activity has never been shown. We hypothesized that at an elevated level, Fg enhances formation of functional caveolae through activation of MMP-9. Male wild-type (WT, C57BL/6J) or MMP-9 gene knockout (MMP9-/-) mice were infused with Fg (4 mg/ml, final blood concentration) or equal volume of phosphate buffered saline (PBS). After 2 h, mice were sacrificed and brains were collected for immunohistochemical analyses. Mouse brain ECs were treated with 4 mg/ml of Fg or PBS in the presence or absence of MMP-9 activity inhibitor, tissue inhibitor of metalloproteinases-4 (TIMP-4, 12 ng/ml). Formation of functional caveolae was assessed by confocal microscopy. Fg-induced increased formation of caveolae, which was defined by an increased co-localization of caveolin-1 (Cav-1) and plasmalemmal vesicle-associated protein-1 and was associated with an increased phosphorylation of Cav-1, was ameliorated in the presence of TIMP-4. These results suggest that at high levels, Fg enhances formation of functional caveolae that may involve Cav-1 signaling and MMP-9 activation.
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University of Louisville, Bldg. A, Room 1115, 500 South Preston Street, Louisville, KY, 40202, USA.
authors.forename: Nino
authors.initials: N
authors.lastname: Muradashvili
authors.forename: Richard L
authors.initials: RL
authors.lastname: Benton
authors.forename: Reeta
authors.initials: R
authors.lastname: Tyagi
authors.forename: Suresh C
authors.initials: SC
authors.lastname: Tyagi
authors.forename: David
authors.initials: D
authors.lastname: Lominadze
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism; D001921:Brain / Q000166:cytology / Q000473:pathology; D002352:Carrier Proteins / Q000378:metabolism; D021941:Caveolae / Q000378:metabolism*; D051242:Caveolin 1 / Q000378:metabolism; D002460:Cell Line; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism* / Q000494:pharmacology; D007150:Immunohistochemistry; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010766:Phosphorylation; D019714:Tissue Inhibitor of Metalloproteinases / Q000494:pharmacology; D000097792:Tissue Inhibitor of Metalloproteinase-4
chemical_list: D002352:Carrier Proteins; D051242:Caveolin 1; D005340:Fibrinogen; D020780:Matrix Metalloproteinase 9; D008565:Membrane Proteins; D019714:Tissue Inhibitor of Metalloproteinases; D000097792:Tissue Inhibitor of Metalloproteinase-4; C486772:Plvap protein, mouse