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Functional analysis of mutants of the optineurin gene, associated with some forms of glaucoma
Author(s) -
BALASUBRAMANIAN D,
CHALASANI M,
SWARUP G,
AGARWAL N
Publication year - 2008
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2008.244.x
Subject(s) - optineurin , microbiology and biotechnology , biology , programmed cell death , retinal ganglion cell , mutant , transfection , cell culture , retinal , mutation , gene , genetics , apoptosis , biochemistry
Purpose Mutations in the gene OPTN are associated with normal tension and open angle glaucomas. We have studied the effects of some of these mutations on the cellular biology of retinal ganglion cells, and tried to infer the role of the protein optineurin. Methods We transfected plasmids expressing normal or wild‐type (WT) and E50K, R545Q, H26D, and H486R mutant optineurin into a variety of cells such as HeLa, COS‐1, retinal pigment epithelial (RPE), and the rat retinal ganglion cell (RGC) line RGC‐5, and followed their effects on cell survival by morphologic observation of cells. Expression of optineurin and its mutants was monitored by immunofluorescence staining of cells and by Western blotting. Results The E50K mutant of optineurin, which is associated with the severest phenotype, was seen to selectively induce the death of retinal ganglion cells but not of the other cell lines tested. Neither the wild type cDNA nor the other mutants have any such effect. This cell death induced by E50K OPTN was inhibited by the antioxidants N‐acetylcysteine and Trolox. E50K was seen to generate reactive oxygen species (ROS), which were reduced by antioxidants. Coexpression of manganese superoxide dismutase with the E50K mutant abolished ROS production and inhibited cell death. Conclusion E50K optineurin is a gain of function mutant, which has acquired the ability to induce cell death selectively in retinal ganglion cells. This cell death was mediated by oxidative stress. The present findings suggest the possibility of antioxidant use for delaying or controlling some forms of glaucoma.