title: PDGF-BB enhances alpha1beta1 integrin-mediated activation of the ERK/AP-1 pathway involved in collagen matrix remodeling by rat mesangial cells.
abstract: Platelet-derived growth factor-BB (PDGF-BB) has been implicated in the pathogenesis of progressive glomerulonephritis (GN). Previous studies have reported that PDGF-BB stimulates mesangial cells (MCs)-induced collagen matrix remodeling through enhancement of alpha1beta1 integrin-dependent migratory activity. To determine the cell signaling pathway responsible for abnormal MC-related mesangial matrix remodeling in progressive GN, we studied the involvement of the extracellular signal-regulated kinase (ERK)/activator protein-1 (AP-1) pathway in PDGF-BB-enhanced collagen gel contraction. Western blotting and gel shift assay revealed that MC-induced gel contraction resulted in ERK activation in parallel with that of AP-1 binding, peaking at 4 h and lasting at least for 24 h. Application of the MEK inhibitor, U0126, and the c-jun/AP-1 inhibitor, curcumin, inhibited gel contraction and AP-1 activity, respectively, dose dependently. PDGF-BB enhanced not only gel contraction but ERK phosphorylation and AP-1 activity by MCs. Marked inhibitory effects on PDGF-BB-induced gel contraction and ERK/AP-1 activity were observed in the presence of either function blocking anti-alpha1- or anti-beta1-integrin antibody or U0126. Consistently, AP-1-inactive MCs expressing a dominant-negative mutant of c-jun showed a significant decrease of PDGF-BB-induced gel contraction as compared with mock-transfected MCs. Finally, migration assay showed that ERK/AP-1 activity is required for PDGF-BB-stimulated alpha1beta1 integrin-dependent MC migration to collagen I. These results indicated that PDGF-BB enhances alpha1beta1 integrin-mediated collagen matrix reorganization through the activation of the ERK/AP-1 pathway that is crucial for MC migration. We conclude that the ERK/AP-1 pathway plays an important role in PDGF-BB-induced alpha1beta1 integrin-dependent collagen matrix remodeling; therefore, the inhibition of its pathway may provide a novel approach to regulate abnormal collagen matrix remodeling in progressive GN.
authors.affiliation: Department of Pediatrics, School of Medicine, University of Tokushima, Tokushima, Japan. kagami@clin.med.tokushima-u.ac.jp
authors.forename: Shoji
authors.initials: S
authors.lastname: Kagami
authors.forename: Maki
authors.initials: M
authors.lastname: Urushihara
authors.forename: Akiko
authors.initials: A
authors.lastname: Kitamura
authors.forename: Shuji
authors.initials: S
authors.lastname: Kondo
authors.forename: Tetsuhiro
authors.initials: T
authors.lastname: Hisayama
authors.forename: Masanori
authors.initials: M
authors.lastname: Kitamura
authors.forename: Klemens
authors.initials: K
authors.lastname: Löster
authors.forename: Werner
authors.initials: W
authors.lastname: Reutter
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kuroda
mesh_terms: D000818:Animals; D000077214:Becaplermin; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D002465:Cell Movement / Q000502:physiology; D003094:Collagen / Q000187:drug effects / Q000378:metabolism*; D003474:Curcumin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism*; D016758:Genes, jun; D005920:Glomerular Mesangium / Q000166:cytology* / Q000378:metabolism; D005921:Glomerulonephritis / Q000503:physiopathology; D039222:Integrin alpha1beta1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D009154:Mutation; D009570:Nitriles / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000502:physiology; D018808:Transcription Factor AP-1 / Q000187:drug effects / Q000378:metabolism; D014162:Transfection
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D039222:Integrin alpha1beta1; D009570:Nitriles; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D018808:Transcription Factor AP-1; C113580:U 0126; D000077214:Becaplermin; D003094:Collagen; D020928:Mitogen-Activated Protein Kinases; D003474:Curcumin