The trabecular meshwork of the eye is the principal site of outflow resistance to the aqueous humor. Our long-term goal is to develop selective gene transfer systems to assist cells in reducing resistance to aqueous humor outflow and thereby stopping visual field loss. We looked at the effects of two prostaglandin derivatives, latanoprost acid and prostamide, that cause reductions in intraocular pressure. The effects of these drugs on both trabecular meshwork cells and on ciliary muscle cells was investigated since both cell types populate areas of the eye where outflow of aqueous is possible. Using gene array analysis we were able to see alterations in gene expression of components related to the extracellular matrix. We verified the results of the gene arrays with real time polymerase chain reactions and with relative quantitative polymerase chain reactions. These results have led us to two components from the trabecular meshwork that might be important in regulating outflow both in normal and diseased conditions. These proteins are migration inhibitory factor, MIF, and SPARC. These proteins influence extracellular matrix turnover. We believe that over expression of either of these proteins might be beneficial in the trabecular meshwork in reducing intraocular pressure. We are studying the effects of these two proteins on human trabecular meshwork cells as well as ciliary muscle cells. These candidates should be useful in gene therapy of glaucoma. We are also studying the protein myocilin. Mutations in this protein have been shown to be associated with some forms of glaucoma. We are attempting to over express normal myocilin in mouse eyes to determine if the intraocular pressure is altered. In addition, we are expressing mutated myocilin to determine how this protein might be altering trabecular meshwork cells and thereby causing glaucoma. Our hypothesis is that the mutated myocilin is interfering with cellular functions and ultimately causing trabecular meshwork cell death. We are currently working on ways to silence mutated myocilin. Silencing this protein should ultimately help the cells in regaining normal function and thereby cause an increase in outflow. This would have the effect of reducing the damage to the retinal ganglion cells.
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