title: MMP-9 controls Schwann cell proliferation and phenotypic remodeling via IGF-1 and ErbB receptor-mediated activation of MEK/ERK pathway.
abstract: Phenotypic remodeling of Schwann cells is required to ensure successful regeneration of damaged peripheral axons. After nerve damage, Schwann cells produce an over 100-fold increase in metalloproteinase-9 (MMP-9), and therapy with an MMP inhibitor increases the number of resident (but not infiltrating) cells in injured nerve. Here, we demonstrate that MMP-9 regulates proliferation and trophic signaling of Schwann cells. Using in vivo BrdU incorporation studies of axotomized sciatic nerves of MMP-9-/- mice, we found increased Schwann cell mitosis in regenerating (proximal) stump relative to wild-type mice. Treatment of cultured primary Schwann cells with recombinant MMP-9 suppressed their growth, mitogenic activity, and produced a dose-dependent, biphasic, and selective activation of ERK1/2, but not JNK and p38 MAPK. MMP-9 induced ERK1/2 signaling in both undifferentiated and differentiated (using dbcAMP) Schwann cells. Using inhibitors to MEK and trophic tyrosine kinase receptors, we established that MMP-9 regulates Ras/Raf/MEK-ERK pathways through IGF-1, ErbB, and PDGF receptors. We also report on the early changes of MMP-9 mRNA expression (within 24 h) after axotomy. These studies establish that MMP-9 controls critical trophic signal transduction pathways and phenotypic remodeling of Schwann cells.
authors.affiliation: Department of Anesthesiology, University of California, San Diego, California 92093-0629, USA.
authors.forename: Sharmila
authors.initials: S
authors.lastname: Chattopadhyay
authors.forename: Veronica I
authors.initials: VI
authors.lastname: Shubayev
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D020935:MAP Kinase Signaling System; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D012583:Schwann Cells / Q000166:cytology* / Q000502:physiology*; D012584:Sciatic Nerve / Q000293:injuries / Q000502:physiology
chemical_list: D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D020794:Receptor Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse