Localization of Apolipoprotein E on lipid droplets across various genotypes in astrocytes

Alzheimer’s Disease (AD) is characterized by 3 main histopathological markers: tau neurofibrillary tangles, amyloid beta plaques, and lipid droplet (LD) accumulation. Apolipoprotein E (APOE) plays a role in lipid transfer among cells and has 3 variants: APOE2, APOE3, and APOE4. APOE4 has the greatest risk for AD and is shown to increase the accumulation of LDs in neuroglial cells. The Cohen Lab has discovered that APOE can traffic to the surface of LDs, regulating LD size and composition. Since APOE plays a role as an LD surface protein, our goal is to profile the composition of APOE on LDs across the 3 APOE genotypes in astrocytes using mouse brain tissue. To quantify the composition of APOE on LD, we performed immunohistochemistry on 5X FAD mouse tissue and stained for APOE, LDs, and amyloid beta plaques, measuring protein expression of APOE, LD volume, and percent colocalization of APOE on LD. Our work is the first to demonstrate the recruitment of APOE on LD in vivo. We found that E2 and E4 predominantly express APOE, and E4 shows an increase in LD levels, demonstrating altered lipid metabolism.