The myocilin (MYOC) gene expression in the human trabecular meshwork

Purpose. We previously reported a novel cytoskeletal protein with a myosin-like domain which is localized in the ciliary rootlet and basal body of connecting cilium of photoreceptor and hence we named it 'myocilin'. It was soon realized that myocilin is identical to a protein called TIGR (trabecular meshwork inducible glucocorticoid response protein) which was found to be responsible for the pathogenesis of juvenile open angle glaucoma. In this study, we employed in situ RNA hybridization to examine the myocilin (MYOC)/TIGR gene expression in the trabecular meshworks of glaucomatous and nonglaucomatous eyes. Methods. The glaucomatous specimens were obtained by trabeculectomy from the patients with primary open angle glaucoma (POAG), chronic angle closure glaucoma (CACG) and steroid glaucoma, respectively, and the nonglaucomatous specimens were obtained from a victim of traffic accident at autopsy and from a patient with maxillary sinus carcinoma at enucleation for the operation. The in situ RNA hybridization was carried out with digoxigenin-labeled sense and antisense RNA probes. Results. In all cases, hybridization signals were detected primarily in the trabecular meshwork cells and secondarily in the fibroblast-like cells of corneoscleral wall. Conclusions. Myocilin gene is expressed clearly in the trabecular meshwork cells of both glaucomatous and nonglaucomatous eyes.