Abstract
Abstract: :
Purpose: To study cellular localization and tissue distribution of Optineurin, a newly identified Glaucoma-causing protein in human, Rhesus monkey and mouse eyes. Methods: Aqueous humor samples from human and 7 other species together with cell lysates and supernatants from various cell lines were investigated by Western blotting. Immunohistochemistry was performed on human, monkey and mouse eye sections. Results: Cloning of mouse and monkey genes revealed proteins with 584 and 571 a.a. and with 78% and 96% identity to human, respectively. Western blotting showed a 68-kDa band in all aqueous humor samples, trabecular meshwork (TM), non-pigmented ciliary epithelium (NPCE), lymphocytes and dermal fibroblast cell lines. By immunohistochemistry, Optineurin was localized with the Golgi apparatus. Immunohistochemistry study of anterior segments showed positive staining with NPCE, ciliary muscle, lens epithelium, iris constrictor muscle and endothelial cells of iris vessels. No immunoreactivity was observed in TM site by immunohistochemistry even though previously we showed presence of both transcript and protein in cultured human TM cells. An intense labeling was seen in Schlemm's canals of all eyes. Positive staining was observed in all parts of retina, nerve fiber layers, ganglion cells, inner and outer nuclear layers, rods and cones cell bodies and most intensely in pigmented epithelium. Immunocytochemistry showed intense labeling in human optic nerve head astrocytes cell lines from normal and glaucomatous eyes. In monkey and mouse axons of optic nerve ganglion cells, glial cells and endothelial cells of optic nerve blood vessels were also stained. Conclusions: This study provides the first report of ocular localization for Optineurin. This protein expressed in most of ocular tissues with relatively strong immunoreactivity in ciliary body, ciliary muscle, retina and optic nerve. We obtained very similar tissue distribution in human, monkey and mouse eyes. These findings are consistent with role of this protein in our previously reported low-pressure glaucoma patients with Optineurin mutations. Supported by EY-09947 and M01RR-06192.
Keywords: proteins encoded by disease genes • immunohistochemistry • ganglion cells