Project Summary: Glaucoma is a disease of the optic nerve causing irreversible blindness and important public health concern with around 76.9 million glaucoma patients, which is set to increase to 111.8 million in 2040. Primary open-angle glaucoma (POAG) is a form of glaucoma characterized by elevated intraocular pressure (IOP). A rise in IOP above normal is a major risk for glaucoma with significant consequences on vision and quality of life. Lowering IOP by 20% significantly decreases the risk of developing glaucoma in patients with elevated IOP. High IOP in the eye is due to the decreased removal of aqueous humor through the trabecular meshwork (TM). Changes in the lipid composition of the TM can modify the actin cytoskeleton interactions can with extracellular structural and biochemical support called the extracellular matrix (ECM) in the drainage pathway. This process can increase the stiffness of the drainage pathway tissue attributing to an increase in the IOP. However, the contributions of TM lipids to stiffness as well as the process of reversing this stiffness have not yet been understood. This is due to the lack of information on the control of lipid signaling events leading to altered stiffness. In our serendipitous and novel observation, we have identified that a transcriptional factor called sterol regulatory element binding protein (SREBP) is activated under constant mechanical stretch and elevated pressure. Inactivating SREBP lowers the actin tension, ECM deposition, enzymes involved in lipid biosynthesis, and most significantly lowers IOP. However, this leaves us with many unanswered questions on how SREBP integrates the biophysical and biochemical entities including TM lipids, membrane tension, actin cytoskeleton, ECM, and TM stiffness to modulate IOP. Towards this, we aim to test the hypothesis that – 1. transcriptional control of lipogenesis by SREBP in the TM outflow pathway is a critical regulator of IOP by A. assessing the correlation between SREBP activation on IOP changes, B. characterizing the SREBP-dependent temporal changes in lipogenic genes and enzymes and the ECM distribution in the TM outflow pathway and C. evaluating the role of IOP in activation of SREBPs, and 2. SREBP activation regulates TM tissue biomechanics by changing the TM cholesterol and phospholipid contents by A. identifying the contributions of major lipogenic rate-limiting enzymes like acetyl CoA carboxylase (ACC) for fatty acid biosynthesis and HMGCoA reductase (HMGCR) for cholesterol biogenesis on ECM remodeling, B. investigating the real- time changes in TM membrane tension, actin and microtubule architecture, and C. defining the cooperative signals between ECM and cellular lipids on the contractile forces generated by the TM under conditions of tuned SREBP activation. Together, this work will uncover the new biology of lipids in TM to modulate IOP and identify novel targets to reduce the disease burden of elevated IOP.