Phosphoinositide signaling in glaucoma: rescue strategies for Lowe syndrome

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ABSTRACT Glaucoma is a leading cause of irreversible blindness. Lowering intraocular pressure (IOP) is the only modifiable target for intervention, but the mechanisms causing elevated IOP remain poorly understood. This proposal builds on our studies of oculocerebrorenal syndrome of Lowe, a rare X-linked disease that presents with congenital glaucoma, the major cause of blindness in these children. OCRL is an inositol phosphatase mutated in Lowe syndrome. This application seeks to restore the phosphoinositide imbalance that underlies Lowe syndrome by targeting inositol-signaling pathways. We have found evidence that restoring phosphoinositide levels in trabecular meshwork cells can rescue the disease in a Lowe mouse model. We have identified patients with Lowe syndrome who are born with congenital glaucoma and have characterized their mutations. We also discovered mTOR signaling defects in these patients. Thus, we hypothesize that modulation of phosphoinositide signaling in the trabecular meshwork will restore aqueous outflow. Our aims are to (1) restore aqueous outflow by viral delivery of OCRL, (2) balance excess PI(4,5)P2 by inhibiting upstream kinase, (3) modulate mTOR signaling in both the mouse model and a human iPSC model of Lowe syndrome. Our work should help determine the role of OCRL in aqueous outflow regulation. Since phosphoinositide signaling is a novel area of IOP control, the experiments should facilitate discovery of new glaucoma therapies that can reduce the burden of blindness.