Insulin-like growth factor-I (IGF-I) and transforming growth factor-beta (TGF-beta) modulate tenascin-C and fibrillin-1 in bullous keratopathy stromal cells in vitro. 2003

M Cristina Kenney, and Nadia Zorapapel, and Shari Atilano, and Marilyn Chwa, and Alexander Ljubimov, and Donald Brown
Department of Ophthalmology, College of Medicine, University of California, Irvine, 101 The City Drive, Building 55, Room 220, Orange, CA 92868, USA. mkenney@uci.edu

OBJECTIVE Pseudophakic bullous keratopathy (PBK) is a major indication for corneal transplantation. Previous studies showed that PBK corneas had increased levels of insulin-like growth factor-I (IGF-I), bone morphogenetic protein-4 (BMP-4), transforming growth factor-beta (TGF-beta), interleukin-1alpha (IL-1alpha) and IL-8. The PBK corneas also had accumulations of tenascin-C (TN-C), fibrillin-1 (Fib-1), matrix metalloproteinase-2 (MMP-2), inflammatory cells but not myofibroblasts. Our goal is to determine if the growth factors/cytokines that are elevated in PBK corneas alter the expression of extracellular matrix (ECM) and/or degradative enzymes in vitro. METHODS Stromal cell cultures from normal and PBK human corneas were established and treated for 6 days with IGF-I, BMP-4, IL-1alpha, IL-8 or TGF-beta1/beta2. Immunostaining, Western blot and dot blot analyses for TN-C, Fib-1, alpha-smooth muscle actin (alpha-SMA, a marker for myofibroblasts) or tissue inhibitor of metalloproteinase-1 (TIMP-1) were performed. RNAs were collected and analyzed with Northern blots for TN-C, Fib-1 and beta(2)-microglobulin. Culture media were analyzed using gelatin zymography with or without ethylenediaminetetraacetic acid (EDTA). Some samples were activated with p-aminophenylmercuric acetate (APMA) and reduction/alkylation, and the degradative activities were measured by the MMP-gelatinase activity assay kit. RESULTS The IGF-I and TGF-beta1/TGF-beta2 increased (a) TN-C protein deposition, and (b) Fib-1 protein and RNA levels, but (c) had no significant affect on TIMP-1, matrix metalloproteinase-2 (MMP-2) or gelatinase activities. TGF-beta1/TGF-beta2 induced alpha-SMA protein (myofibroblasts) while IGF-I did not. BMP-4, IL-1alpha and IL-8 had little affect on the cells. CONCLUSIONS Based upon our data, the fibrotic markers, TN-C and Fib-1, found in PBK corneas may be accounted for by IGF-I and TGF-beta. These growth factors promote fibrosis and ECM deposition without promoting proteolysis. While the other growth factors/cytokines are elevated in PBK corneas, their role(s) in PBK pathogenesis are not clear. In addition, exogenous IGF-I most closely elicited a response that was most similar to the characteristics of the PBK/ABK corneas, i.e. accumulation of TN-C and Fib-1 proteins in the absence of myofibroblasts.

UI MeSH Term Description Entries
D007334 Insulin-Like Growth Factor I A well-characterized basic peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like, and mitogenic activities. This growth factor has a major, but not absolute, dependence on GROWTH HORMONE. It is believed to be mainly active in adults in contrast to INSULIN-LIKE GROWTH FACTOR II, which is a major fetal growth factor. IGF-I,Somatomedin C,IGF-1,IGF-I-SmC,Insulin Like Growth Factor I,Insulin-Like Somatomedin Peptide I,Insulin Like Somatomedin Peptide I
D008840 Microfilament Proteins Monomeric subunits of primarily globular ACTIN and found in the cytoplasmic matrix of almost all cells. They are often associated with microtubules and may play a role in cytoskeletal function and/or mediate movement of the cell or the organelles within the cell. Actin Binding Protein,Actin-Binding Protein,Actin-Binding Proteins,Microfilament Protein,Actin Binding Proteins,Binding Protein, Actin,Protein, Actin Binding,Protein, Actin-Binding,Protein, Microfilament,Proteins, Actin-Binding,Proteins, Microfilament
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D003316 Corneal Diseases Diseases of the cornea. Corneal Disease,Disease, Corneal,Diseases, Corneal
D005109 Extracellular Matrix A meshwork-like substance found within the extracellular space and in association with the basement membrane of the cell surface. It promotes cellular proliferation and provides a supporting structure to which cells or cell lysates in culture dishes adhere. Matrix, Extracellular,Extracellular Matrices,Matrices, Extracellular
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000071837 Fibrillins A family of extracellular matrix glycoproteins that is structurally similar to LATENT TGF-BETA BINDING PROTEINS, but contain additional TGF-beta binding domains, in addition to unique domains at their N and C-terminals. Fibrillins assemble into 10-12 nm MICROFIBRILS that function in a variety of cell interactions with the EXTRACELLULAR MATRIX and developmental processes such as ELASTIC TISSUE maintenance and assembly, and the targeting of growth factors to the extracellular matrix. Fibrillin
D000071838 Fibrillin-1 A fibrillin (FBN1) that functions as a structural support protein for MICROFIBRILS. It also regulates the maturation of OSTEOBLASTS by controlling the availability and concentration of TGF-BETA and BONE MORPHOGENETIC PROTEINS. Mutations in the FBN1 gene are associated with MARFAN SYNDROME. Profibrillin 1,Profibrillin-1,Fibrillin 1
D015152 Blotting, Northern Detection of RNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES. Northern Blotting,Blot, Northern,Northern Blot,Blots, Northern,Blottings, Northern,Northern Blots,Northern Blottings
D015153 Blotting, Western Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes. Immunoblotting, Western,Western Blotting,Western Immunoblotting,Blot, Western,Immunoblot, Western,Western Blot,Western Immunoblot,Blots, Western,Blottings, Western,Immunoblots, Western,Immunoblottings, Western,Western Blots,Western Blottings,Western Immunoblots,Western Immunoblottings

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