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Nadia benabbou, Alexandre Berthaut, Pezhman Mirshahi, Amu Therwath, Massoud Mirshahi, Jean Marc Legeais; Insulin Growth Factor Promotes Human Corneal Fibroblast Network Formation In Vitro. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2529.
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© ARVO (1962-2015); The Authors (2016-present)
Keratocyte reticulation is involved in the structural development of corneal stroma and in wound healing. Previously, we have reported that the expression of VEGFR-1 by corneal fibroblasts is related to their reticulogenic properties in vitro and decreased with the age of donors. Presently, we have focused our interest on the non-reticulogenic corneal fibroblast population and have investigated whether these cells can be induced to form cell-network, in vitro, under experimental conditions.
The network formation was analyzed using an array of signaling pathway inhibitors wortmannin for PI3 kinase, UO126 for MEK-1/2 kinase, Rottlerin for PkC, Farneysl transferase inhibitor (FTI-277) for Ras and picropodophyllin an IGFR-1 inhibitor. Among several growth factors studied, we came upon IGF which seemed also to be crucial to cell network formation. The presence of IGF signaling was demonstrated using gene array analaysis, confirmed by RT-PCR as well as by immunocytochemistry and cell network formation on reduced matrigel. Pleiotropic effect of IGF-1 on the cells was analyzed by protein cytokines array.
We identified that the genesis of reticulation occurred via MEK-1/2 and IGFR pathways since inhibitors of these signaling pathways were able to reduce or prevent cell network formation. The addition of exogenous IGF-1 was able to generate cell network structure in corneal fibroblasts obtained from healthy donors indicating the involvement of IGF-1.
IGF signaling and MEK-1/2 pathway is involved in the cell network formation of corneal fibroblasts cells from aged donors. However, the exogenous IGF increase also adhesion molecule expressions (Tie-1, Tie-2, L-selectine, Siglec-5 and IL 13 beta) and seems to orient them via the TGF beta axis, towards differentiation of fibroblasts into myofibroblasts.
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