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N. Vij, L. Roberts, S. Joyce, S. Chakravarti; Lumican Binds Fasl and Modulates Fas–Fasl Signaling in the Cornea . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2806.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Our ongoing studies suggest that Fas–FasL signaling is disrupted in the lumican–null mouse cornea. Here we investigated the underlying mechanism in lumican–mediated regulation of Fas–FasL signaling. Methods: Fas levels were measured in tissues by western blotting. A polyclonal anti–lumican (Chakravarti 1998, JCB 141:1277) was used to immunoprecipitate lumican and co–immunoprecipitation of FasL was detected using a polyclonal antibody. Recombinant lumican was synthesized using pSecTag2 (Invitrogen) as described earlier (Vij et al., 2004, Exp. Eye Res., 78:957). Binding between recombinant lumican and Fas L was confirmed by a solid–state binding assay. Results: Immunoblotting showed a dramatic reduction in Fas in the Lum–/– cornea and corneal fibroblasts in culture. Exposure of fibroblasts to FasL or bacterial lipopolysaccharide resulted in poor induction of Fas in lumican–deficient cells compared to wildtype cells. In a solid state–binding assay, recombinant lumican was able to bind to FasL in a dose–dependent manner (0.2 12.8 ∝g/ml of bound FasL). Conclusions: Our results indicate binding of lumican to FasL. Lumican may have a novel role in binding FasL and presenting it to Fas, or stabilizing Fas–FasL complexes at the cell surface in Fas mediated signaling in apoptosis and innate immune response in the cornea.
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