title: A gradient of matrix-bound FGF-2 and perlecan is available to lens epithelial cells.
abstract: Fibroblast growth factors play a key role in regulating lens epithelial cell proliferation and differentiation via an anteroposterior gradient that exists between the aqueous and vitreous humours. FGF-2 is the most important for lens epithelial cell proliferation and differentiation. It has been proposed that the presentation of FGF-2 to the lens epithelial cells involves the lens capsule as a source of matrix-bound FGF-2. Here we used immunogold labelling to measure the matrix-bound FGF-2 gradient on the inner surface of the lens capsule in flat-mounted preparations to visualize the FGF-2 available to lens epithelial cells. We also correlated FGF-2 levels with levels of its matrix-binding partner perlecan, a heparan sulphate proteoglycan (HSPG) and found the levels of both to be highest at the lens equator. These also coincided with increased levels of phosphorylated extracellular signal-regulated kinase 1 and 2 (pERK1/2) in lens epithelial cells that localised to condensed chromosomes of epithelial cells that were Ki-67 positive. The gradient of matrix-bound FGF-2 (anterior pole: 3.7 ± 1.3 particles/μm2; equator: 8.2 ± 1.9 particles/μm2; posterior pole: 4 ± 0.9 particles/μm2) and perlecan (anterior pole: 2.1 ± 0.4 particles/μm2; equator: 5 ± 2 particles/μm2; posterior pole: 1.9 ± 0.7 particles/μm2) available at the inner lens capsule surface was measured for the bovine lens. These data support the anteroposterior gradient hypothesis and provide the first measurement of the gradient for an important morphogen and its HSPG partner, perlecan, at the epithelial cell-lens capsule interface.
authors.affiliation: Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, United Kingdom.
authors.forename: Weiju
authors.initials: W
authors.lastname: Wu
authors.affiliation: NETPark Incubator, Thomas Wright Way, Sedgefield, Durham TS21 3FD, United Kingdom.
authors.forename: Frederique M
authors.initials: FM
authors.lastname: Tholozan
authors.affiliation: Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, United Kingdom.
authors.forename: Martin W
authors.initials: MW
authors.lastname: Goldberg
authors.affiliation: Biophysical Sciences Institute, Department of Physics, Durham University, Durham DH1 3LE, United Kingdom.
authors.forename: Leon
authors.initials: L
authors.lastname: Bowen
authors.affiliation: Biophysical Sciences Institute, School of Engineering and Computing Sciences, Durham University, Durham DH1 3LE, United Kingdom.
authors.forename: Junjie
authors.initials: J
authors.lastname: Wu
authors.affiliation: Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, United Kingdom. Electronic address: r.a.quinlan@dur.ac.uk.
authors.forename: Roy A
authors.initials: RA
authors.lastname: Quinlan
mesh_terms: D000818:Animals; D002417:Cattle; D024141:Collagen Type IV / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism*; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism*; D007150:Immunohistochemistry; D007903:Lens Capsule, Crystalline / Q000378:metabolism* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010766:Phosphorylation
chemical_list: D024141:Collagen Type IV; D019812:Heparan Sulfate Proteoglycans; D016222:Fibroblast Growth Factor 2; C071927:perlecan; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3
keywords: ERK1/2; FGF-2; lens capsule; perlecan