title: EGF-R regulates MMP function in fibroblasts through MAPK and AP-1 pathways.
abstract: EGF-R regulates cell proliferation, migration, and invasion in fibroblasts. However, the connection of EGF-R with downstream signaling pathways mediating these responses has remained elusive. Here we provide genetic and biochemical evidence that EGF-R- and AP-1-mediated signals are required for MMP expression and collagen contraction in fibroblasts. In EGF-R (-/-) mouse embryonal fibroblasts, basal and inducible expression of several MMPs, including MMP-2, -3, and -14 is impaired in comparison to wild-type counterparts. The loss of MMP expression is associated with a suppression of EGF-induced Erk and Jnk activities, and AP-1 DNA-binding and transactivation capacities. While inhibition of Jnk mainly prevents EGF-induced phosphorylation of c-Jun, inhibition of Erk pathway suppresses both the expression and phosphorylation of c-Jun and c-Fos proteins. Moreover, the expression of MMP-3 and -14, and collagen contraction is partially prevented by Mek/Erk and Jnk inhibitors. However, Jnk inhibitor also suppresses cell growth independently of EGF-R activity. The central role of AP-1 as a mediator of EGF-R signaling in fibroblasts is emphasized by the finding that expression of a dominant negative c-Jun downregulates the expression of MMP-3. Conversely, expression of a constitutively active Mek1 can induce MMP-3 expression independently of upstream signals. The results indicate that ERK pathway and AP-1 are downstream effectors of the EGF-R-mediated MMP-3 expression and collagen contraction in fibroblasts.
authors.affiliation: Molecular Cancer Biology Research Program, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Kajanne
authors.forename: Päivi
authors.initials: P
authors.lastname: Miettinen
authors.forename: Annika
authors.initials: A
authors.lastname: Mehlem
authors.forename: Suvi-Katri
authors.initials: SK
authors.lastname: Leivonen
authors.forename: Michael
authors.initials: M
authors.lastname: Birrer
authors.forename: Marco
authors.initials: M
authors.lastname: Foschi
authors.forename: Veli-Matti
authors.initials: VM
authors.lastname: Kähäri
authors.forename: Sirpa
authors.initials: S
authors.lastname: Leppä
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D003094:Collagen / Q000378:metabolism; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D066246:ErbB Receptors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005347:Fibroblasts / Q000201:enzymology / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D003094:Collagen; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020782:Matrix Metalloproteinases; D019278:Matrix Metalloproteinase 3; D020778:Matrix Metalloproteinase 2; D053511:Matrix Metalloproteinase 14