Latent-Transforming growth factor - β Binding protein 1 (LTBP1) in corneal stroma.

We aim to determine the presence and function of LTBP1 in the corneal stroma. We investigated the temporal and spatial corneal expression of LTBP1, and microfibril-associated glycoprotein 1 (MAGP1), known components of the elastic system and regulators of TGF-β storage and latency. Protein quantification -blotting and proteomics-, immunofluorescence microscopy, mRNA analysis and a luciferase assay were used to study the regulation of transforming growth factor β (TGF-β) by LTBP1 in cornea derived fibroblasts and myofibroblasts. Expression of LTBP1 and MAGP1 was found in adult corneas, and absent or minimal in the scleral stroma. Quantitative polymerase chain reaction and protein blotting analyses showed upregulation of these proteins during early postnatal development and deposition in the corneal matrix with tissue maturation. In vitro, LTBP1 regulated the conversion of fibroblasts to myofibroblasts and maintained TGF-β latent in the matrix. This study shows that LTBP1 and MAGP1, regulators of TGF-β activation and elastic fiber components, are found in adult stroma. LTBP1 is a regulator of TGF-β storage and latency and controls conversion of fibroblast to myofibroblast.