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T. Rezaie, M.B. Wax, D.P. Edward, M. Sarfarazi; Expression of Optineurin Protein in Human Normal and Glaucomatous Eyes . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1260.
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© ARVO (1962-2015); The Authors (2016-present)
Our previous studies showed that mutations in the Optineurin (OPTN) gene are involved in etiology of the GLC1E–linked adult–onset primary open–angle glaucoma (Science 295:1077; 2002). In this study we aimed to examine distribution and cellular localization of the human optineurin protein in ocular tissues of normal, normal–pressure glaucoma (NPG), and eyes with chronic inflammation.
Ocular paraffin sections were used for immunohistochemistry analyses. A peptide antibody against the C–terminus of optineurin was developed and its specificity was confirmed by various experimental methods. Immunofluorescence labeling was performed to investigate expression and localization of the optineurin protein in human eyes. Control experiments for nonspecific staining included replacement of the primary anti–OPTN antibody with preimmune serum. Confocal microscope was used to visualize the slides.
By immunohistochemistry, positive optineurin labeling was observed in corneal epi– and endothelium. Iris stroma and smooth muscle cells of the constrictor muscle as well as vascular endothelium of the iris vessels also found to be immunoreactive. In the anterior segment, predominant staining was detected in non–pigmented ciliary epithelium, ciliary muscle, Schlemm’s canal endothelium as well as trabecular meshwork and collagen bundles of the adjacent sclera. In retina, axons of the optic nerve ganglion cells, inner and outer plexiform layers as well as rods and cones stained for OPTN. Immunoreactivity of vascular endothelium cells for optineurin protein was very prominent in the ocular tissues. No labeling was observed in any of the control sections tested.
Optineurin is a glaucoma–causing gene that encodes for a protein with unknown function. This protein is intracellularly localized to the Golgi apparatus. In this study, cytoplasmic expression of OPTN in almost every ocular tissue was established. This expression was relatively more prominent in retina, iris, ciliary body and trabecular meshwork. Previously, we showed high expression of OPTN protein in human normal and glaucomatous optic nerve head astrocytes (Ophthalmol Clin North Am. 16:529; 2003) but this study further revealed a high degree of similarity between expression and localization of OPTN with our previous observations in ocular tissues and optic nerves in Rhesus Monkey (IOVS 46:2404; 2005) and Mouse (Genomics 85:131; 2005).
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