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J. S. Crabb, K. E. Bollinger, X. Yuan, X. Yue, A. F. Clark, J. W. Crabb; Quantitative Proteomic Analysis of Dexamethasone-Treated Human Trabecular Meshwork Cells. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3206.
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© ARVO (1962-2015); The Authors (2016-present)
Corticosteroids are commonly used anti-inflammatory drugs that can increase intraocular pressure and cause secondary glaucoma. Toward better understanding the mechanisms underlying steroid-induced glaucoma, we evaluated quantitative proteomic changes in cultured trabecular meshwork (TM) cells following dexamethasone-treatment.
Primary cultures of human TM cells from 2 glaucomatous and 2 non-glaucomatous donors were treated with or without dexamethasone (100 nM) for 10 days. Protein was extracted, digested with trypsin, peptides labeled with iTRAQ tags, and dexamethasone-treated TM samples were combined with their corresponding untreated samples. Following strong cation exchange chromatography, peptides were analyzed by LC MS/MS and proteins were identified using the Mascot search engine and the Swiss-Protein database. Relative protein quantification from iTRAQ labeling utilized code written in R. Immunoblotting was used to corroborate differential expression of select proteins.
A total of 718 proteins were quantified with 2 or more peptides from dexamethasone-treated TM cells. No definitive proteomic differences were detected between glaucomatous and control TM cells. Among proteins quantified in at least 3 of the 4 TM samples, the abundance of 20 proteins increased and 20 proteins decreased significantly with dexamethasone-treatment. Sorbin and SH3 domain-containing protein 2, nexilin, and CD166 antigen were the most significantly elevated, while collagen α-1(I), serpin H1, and UDP-glucose 6-dehydrogenase were the most significantly decreased proteins.
Dexamethasone-induced increased protein expression could alter TM cell adhesion, cell migration and cytoskelatal organization while reduced protein expression could compromise the structural integrity of the ECM associated with the TM. These results suggest that such proteomic changes could contribute to aqueous outflow resistance in the TM and may play a role in the molecular mechanisms of glaucoma pathology.
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