title: Fibroblast growth factor receptor-1 signaling in pancreatic islet beta-cells is modulated by the extracellular matrix.
abstract: Maintenance of pancreatic beta-cell mass depends on extracellular stimuli that promote survival and proliferation. In the islet, these stimuli come from the beta-cell microenvironment and include extracellular matrix deposited by associated vascular endothelial cells. Fibroblast growth factor receptor-1 (FGFR1) has recently been implicated as a signaling pathway that is important for normal beta-cell function. We would like to understand how extracellular matrix and FGFR1 signaling interact to promote beta-cell survival and proliferation. To examine beta-cell-specific receptor responses, we created lentiviral vectors with rat insulin promoter-driven expression of Venus fluorescent protein-tagged full-length (R1betav) and kinase-deficient (KDR1betav) FGFR1. Significant FGF-1-dependent activation of ERK1/2 was observed in betaTC3 cells, dispersed beta-cells, and beta-cells in intact islets. This response was enhanced by R1betav expression and reduced by KDR1betav expression. Plating-dispersed beta-cells on collagen type IV resulted in enhanced expression of endogenous FGFR1 that was associated with sustained activation of ERK1/2. Conversely, plating cells on laminin reduced expression of FGFR1, and this reduction was associated with transient activation of ERK1/2. Addition of neutralizing antibodies to inhibit beta-cell attachment to laminin via alpha(6)-integrin increased high-affinity FGF-1-binding at the plasma membrane and resulted in sustained ERK1/2 activity similar to cells plated on collagen type IV. These data show that the FGF-stimulated beta-cell response is negatively affected by alpha(6)-integrin binding to laminin and suggest regulation associated with vascular endothelial cell remodeling.
authors.affiliation: Cell Imaging Shared Resource, Vanderbilt University Medical Center, Nashville, Tennessee 37232-0615, USA.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Kilkenny
authors.forename: Jonathan V
authors.initials: JV
authors.lastname: Rocheleau
mesh_terms: D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000378:metabolism / Q000502:physiology*; D016220:Fibroblast Growth Factor 1 / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000378:metabolism; D039503:Integrin alpha6 / Q000378:metabolism; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: D039503:Integrin alpha6; D007797:Laminin; D020033:Protein Isoforms; D016220:Fibroblast Growth Factor 1; D051496:Receptor, Fibroblast Growth Factor, Type 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3