Research

“Live the questions now. Perhaps then, someday…you will gradually, without even noticing it, live your way into the answer.”  ~  Rainer Maria Rilke

Research in the Lakkaraju laboratory aims to harness the power of translational cell biology to develop effective therapies for devastating retinal diseases that cause irreversible vision loss. We focus on the retinal pigment epithelium (RPE), a key site of injury in inherited and age-related macular degenerations (AMD), which affect millions of people worldwide and have few therapeutic options. To gain insight into disease pathogenesis, my research team investigates mechanisms that regulate critical pathways such as cellular clearance, inflammation and immune privilege in the retina.

We have shown that as the RPE ages, it becomes less efficient at digesting and recycling ingested outer segments and other cellular waste (Toops et al., Mol Biol Cell, 2015).  This is because over a lifetime, vitamin A metabolites formed as by-products of the visual cycle trap cholesterol within RPE degradative compartments.  Excess cholesterol causes traffic jams within the cell by activating acid sphingomyelinase (ASMase), which interferes with microtubule-based organelle transport.  This interferes with autophagy and lysosome function and also makes the RPE more susceptible to pro-inflammatory stimuli.

Fig4 mitochondria_Nov20 We recently identified two critical mechanisms – rapid recycling of the complement-regulatory protein CD59 and membrane repair by lysosome exocytosis – that are essential for limiting complement-induced inflammation in the RPE (Tan et al., PNAS, 2016). These studies build on earlier work from the lab where we identified the molecular machinery required for polarized lysosome exocytosis in epithelial monolayers (Xu et al., J Cell Sci, 2012). In models of macular degeneration, cholesterol-mediated activation of ASMase derails organelle traffic and inhibits both protective responses, leading to mitochondrial injury after complement attack.

These studies helped identify FDA-approved ASMase inhibitors as promising drugs for macular degenerations (Lakkaraju et al., US Patent P140282US01).

broad conclusions and ASMase inhibitors_simplified

Our laboratory uses high-speed, high-resolution live imaging of fully differentiated adult primary RPE to visualize intricate cellular processes with unprecedented detail (Toops et al., Exp Eye Res, 2014), cellular and molecular techniques and mouse models of disease.

Current areas of research:

1. Mechanisms that regulate organelle biogenesis, autophagy and lysosome function in the RPE (funded by grants from the NIH and the Retina Research Foundation).

2. Mitochondria, oxidative stress and inflammation (funded by grants from the Macular Society UK and the Research to Prevent Blindness foundations).

3. Inter-retinal communication and ocular immune privilege in drusen formation/regression (funded by grants from the BrightFocus Foundation and the NIH).

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