Regulators of Photoreceptor Aerobic Glycolysis in Retinal Health and Disease

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PROJECT SUMMARY/ABSTRACT The Warburg Effect (WE) is the enhanced anaerobic conversion of glucose to lactate observed in tumor and retinal cells, even in normoxia. Both tumor and retinal cells repurpose glucose for anabolic biosynthesis of lipid, protein, RNA/DNA, and antioxidant molecules. In the retina, dysregulation of anabolic processes is associated with age-related macular degeneration (AMD), which afflicts 15 million Americans with devastating effects on their vision. Anabolic processes are regulated by the glycolytic enzymes pyruvate kinase M2 (PKM2) and aldolase. Aldolase promotes anabolism by regulating PKM2 activity (conversion of phosphoenolpyruvate [PEP] to pyruvate [Pyr]), which is controlled by its phosphorylation status. Furthermore, anti-PKM2 and anti-ALDOC antibodies have been identified in AMD patient retinas, implicating their involvement in anabolic dysregulation in AMD pathogenesis. Thus, understanding the interplay between PKM2 and ALDOC - two key mediators of the WE - will help elucidate the mechanisms by which anabolic processes are regulated in healthy retinas and how they are dysregulated in pathogenic conditions. Our preliminary studies show that non-receptor tyrosine kinase Src phosphorylates PKM2 in vitro. Our earlier studies show that in the retina Src activation and PTP1B activity inhibition are light- and rhodopsin-dependent. We will test the hypothesis that cSrc and PTP1B regulate PKM2 phosphorylation, thereby determining the mechanism of light- and rhodopsin-dependent regulation of anabolism in photoreceptor (PR) cells (Aim 1). In Aim 2, we will test the hypothesis that ALDOC affects PKM2 in diverse ways in the PR and retinal pigment epithelial (RPE) cells, thereby determining the regulatory role of ALDOC in RPE and PR cells. Aim 3 will test the hypothesis that retinal aging and AMD are accompanied by a PKM2-dependent dynamic change in actively translated mRNA repertoire, thereby elucidating the role of PKM2 in regulating PR and RPE gene expression The outcome of this project will be a deeper understanding of how mediators of the WE regulate retina structure, functions, and viability. This knowledge is fundamentally important for understanding how PR and RPE cells function and stay alive in normal and pathologic conditions, and are directly relevant to the mission of the National Eye Institute, NIH. Successful completion of these studies will pave the path for developing strategies to prevent/delay retinal degeneration.