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DH Jung; Expression of Wild Type and Truncated Myocilins in Trabecular Meshwork Cells: their Cytotoxicities and Subcellular Localizations . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1047.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:To investigate the cytotoxicities and subcellular localizations of wild type and truncated (Q368X) myocilin in cultured human trabecular meshwork (TM) cells. Methods:GFP and GFP tagged truncated myocilin, full-length myocilin, and stromelysin were expressed in TM cells using adenoviral vectors and their secretory properties and the cytopathic effects in the cells were examined by western blotting and WST-1 cell proliferation assay, respectively. To determine the subcellular localizations of myocilins, cellular organelles of the infected TM cells were stained with antibodies or organelle specific fluorescent indicators and examined under confocal microscope. Results:Truncated myocilin inhibited the secretion of normal myocilin as previously described, but not that of stromelysin. The protein was found to be accumulated as aggregates in ER instead of secretion and its accumulation was found to be toxic to cells, leading to deformed cellular morphology and diminished cell proliferation. Wild type myocilin was expressed as discrete fine vesicles in the perinuclear region of TM cells and was also localized in ER, but not in microtubules or mitochondria. Colocalization of wild type and truncated myocilin, indicative of in vivo interaction of the proteins, was also observed in cells co-expressing the proteins. Conclusion:TM cells participate in the turnover of trabecular extracellular matrix (ECM) components by synthesizing and degrading them continuously. The intracellular accumulation of truncated myocilin is believed to cause a dysfunction of the cells, resulting in alterations in structural compartmentalization of trabecular ECM and obstruction of aqueous outflow.
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