title: IGF-1 Regulates the Extracellular Level of Active MMP-2 and Promotes Müller Glial Cell Motility.
abstract: OBJECTIVE
  In ischemic proliferative retinopathies, Müller glial cells (MGCs) acquire migratory abilities. However, the mechanisms that regulate this migration remain poorly understood. In addition, proliferative disorders associated with enhanced activities of matrix metalloproteinases (MMPs) also involve insulin-like growth factor (IGF)-1 participation. Therefore, the main interest of this work was to investigate the IGF-1 effect on the extracellular proteolytic activity in MGCs.
  
  
  METHODS
  Cell culture supernatants and cell lysates of the human MGC line MIO-M1 stimulated with IGF-1 were analyzed for MMP-2 by zymographic and Western blot analysis. The MGCs' motility was evaluated by scratch wound assay. The MMP-2, β1-integrin, and focal adhesions were detected by confocal microscopy. The localization of active MMPs and actin cytoskeleton were evaluated by in situ zymography.
  
  
  RESULTS
  The IGF-1 induced the activation of canonical signaling pathways through the IGF-1R phosphorylation. Culture supernatants showed a relative decrease in the active form of MMP-2, correlating with an increased accumulation of MMP-2 protein in the MGCs' lysate. The IGF-1 effect on MMP-2 was abolished by an IGF-1R blocking antibody, αIR3, as well as by the PI3-kinase inhibitor, LY294002. The IGF-1 increased the migratory capacity of MGCs, which was blocked by the GM6001 MMP inhibitor, LY294002 and αIR3. Finally, IGF-1 induced the intracellular distribution of MMP-2 toward cellular protrusions and the partial colocalization with β1-integrin and phospo-focal adhesion kinase signals. Gelatinase activity was concentrated along F-actin filaments.
  
  
  CONCLUSIONS
  Taken together, these data indicate that IGF-1, through its receptor activation, regulates MGCs' motility by a mechanism that involves the MMP-2 and PI3K signaling pathway.
authors.affiliation: Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET) Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: Valeria E
authors.initials: VE
authors.lastname: Lorenc
authors.affiliation: Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET) Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: Javier R
authors.initials: JR
authors.lastname: Jaldín-Fincati
authors.affiliation: Departamento de Vítreo-Retina, Centro Privado de Ojos Romagosa-Fundación VER, Córdoba, Argentina.
authors.forename: José D
authors.initials: JD
authors.lastname: Luna
authors.affiliation: Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET) Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Chiabrando
authors.affiliation: Centro de Investigaciones en Bioquímica Clínica e Inmunología (CIBICI-CONICET) Departamento de Bioquímica Clínica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
authors.forename: María C
authors.initials: MC
authors.lastname: Sánchez
mesh_terms: D015153:Blotting, Western; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D063928:Ependymoglial Cells / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D019012:Integrin beta1 / Q000502:physiology; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism* / Q000502:physiology; D018613:Microscopy, Confocal; D015398:Signal Transduction / Q000502:physiology
chemical_list: D019012:Integrin beta1; D007334:Insulin-Like Growth Factor I; D020778:Matrix Metalloproteinase 2