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Min Hyung Kang, Dong-Jin Oh, Douglas J Rhee; Overexpression of thrombospondin-1 (TSP1) in Human Trabecular Meshwork Alters Extracellular Matrix. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3281.
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© ARVO (1962-2015); The Authors (2016-present)
Thrombospondins-1 (TSP1) is a matricellular protein which has been shown to regulate cytoskeleton, cell adhesion, and extracellular matrix remodeling. TSP-1 is found in the trabecular meshwork (TM) and is increased in one third of patients with primary open-angle glaucoma (POAG). As TSP1-null mice demonstrated a lower IOP resulting from increased outflow, we hypothesized that TSP1 overexpression would alter IOP by affecting extracellular matrix (ECM) synthesis and/or turnover in the trabecular meshwork (TM).
An adenoviral vector including the cDNA of human TSP1 (Ad-TSP1) was constructed using the Ad5 vector system. Ad-TSP1 was then used to overexpress TSP1 in human TM endothelial cells at the multiplicity of infections (MOI) 50. ECM proteins from cell lysates and conditioned media were analyzed by immunoblotting.
By infecting human TM endothelial cells in culture with Ad-TSP1, we observed that TSP1 was overexpressed (3.5 ± 3.2 fold, p=0.17, n=5), compared to Ad-cont. Overexpressed TSP1 induced the elevation of collagen IV (2.3 ± 0.88 fold, p=0.03, n=5). Collagen I (1.9 ± 2.7 fold, p=0.48, n=5) was not affected. Fibronectin (2.2 ± 1.7 fold, p=0.17, n=5) showed a trend of elevation, but was not significant.
TSP1 overexpression elevated the level of ECM proteins. Combined together with lowering IOP in TSP-1 null mice, TSP1 could be a regulatory node for IOP by altering ECM proteins in the human TM.
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