Development of appropriate animal models of glaucoma is a critical step for understanding the molecular mechanisms of this blinding disease. We are developing a novel mouse model of glaucoma using a transgenic approach. It is now well established that mutations in the myocilin gene may lead to juvenile open-angle glaucoma and, in some cases, to adult onset glaucoma. The most severe mutations in this gene interfere with secretion of the encoded protein, and may compromise a secretory pathway in the tissues of the eye angle. In collaboration with Dr. E. Wawrousek, we produced several lines of transgenic mice containing BAC (bacterial artificial chromosome) with a point mutation in the human (Tyr437His) or mouse (Tyr423His) myocilin gene. This mutation in human myocilin leads to severe glaucoma. One line of transgenic mice expressing the mutated mouse myocilin was characterized first. We demonstrated that expression of the mutated mouse myocilin gene in the eye trabecular meshwork leads to a moderate elevation of intraocular pressure to13.3 ? 0.4 mmHg in transgenic mice from 11 ? 0.3 mmHg in control animals. The elevation of intraocular pressure was accompanied by a 20-25% decrease in a number of ganglion cells in the peripheral retina of one year old transgenic mice compared to control animals. Changes in the gene expression pattern in the eye of transgenic animals were demonstrated using an array hybridization technique. Our data indicate that transgenic mice expressing mutated mouse and human myocilin may represent a very useful genetic model of glaucoma. We continue to study properties of a novel olfactomedin domain-containing protein, optimedin, which we previously identified. We produced several stably transfected PC12 cell lines expressing optimedin under the control of an inducible promoter. We demonstrated that expression of optimedin stimulated aggregation of PC12 cells and inhibited neurite outgrowth during cell differentiation into a neuronal cell type in the presence of the nerve growth factor. We showed that optimedin may interact with another olfactomedin domain-containing protein, olfactomedin-2. We investigated properties of a novel gene encoding a protein containing PDZ and Lim domains, which we previously identified in the rat eye angle library and named Pdlim2. We demonstrated that the Pdlim2 protein interacts with different actin-binding proteins, including alpha-actinins, filamin A and non-muscle myosin heavy chain IIA (Myh9). Our results suggest that Pdlim2 may act as an adapter that directs other proteins to the cytoskeleton.
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