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R. Metlapally, A.I. Jobling, A. Gentle, N.A. McBrien; Integrin Receptor Profile in the Mammalian Sclera and Functional Implications for Myopia . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3334.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Scleral remodelling during myopia development results in altered biomechanical properties of the sclera. Previous data have implicated major collagen–binding integrin receptors in scleral remodelling during myopia development. However, it is unknown how many of the 24 integrin receptors are present in the sclera. This study examined the integrin receptor expression profile in the mammalian sclera in vivo and in vitro and investigated their functional role in scleral fibroblasts. Methods: Tree shrew total RNA was obtained from posterior scleral tissue as well as cultured scleral fibroblasts. The presence of individual integrin subunits was investigated using RT–PCR and automated sequencing. Skin, lung, liver, kidney and heart samples were used as positive controls. Since integrins are known to influence fibroblast contractility, which contributes to the biomechanical properties of the sclera, 3D collagen matrices were used to assess the contractile properties of scleral fibroblasts. Results: Four of the eight known integrin ß subunits, ß1, ß4, ß5 and ß8 were identified in vivo and in vitro in the mammalian sclera. The subunits, α1, α2, α5, α6, α9, α10, α11 and αV were also expressed in scleral tissue as well as cultured fibroblasts while α3, α4, α7 and α8 were not detected though they are able to bind the ß1 subunit. The tree shrew integrin sequences showed high identity to their human counterparts (>84%). Primary cultures of scleral fibroblasts expressing the above integrins rapidly contracted stressed 3D collagen matrices, with matrix surface area reduced by 51% within 6 hours. Conclusions: The identified subunits have the potential to form 11 integrin receptors within the sclera. These receptors bind various extracellular matrix ligands that are important in tissue remodelling and have been reported in the sclera. Scleral fibroblasts are highly contractile and may resist ocular elongation. As integrins are involved in cell–extracellular matrix interactions, these scleral receptors may influence contractile properties of the sclera during myopia development.
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