APOE4 drives widespread changes to the hepatic proteome and alters metabolic function

Abstract

Apolipoprotein E (APOE) is essential for lipid homeostasis and has been extensively studied in the central nervous system, particularly in the context of Alzheimer's disease (AD). Individuals carrying an APOE4 allele have an increased risk of AD and exhibit deficits in energy metabolism, including glucose utilization and mitochondrial dysfunction. While the role of APOE in the liver is well characterized, the impact of APOE genetic variation on hepatic health and metabolism remains poorly understood. We sought to investigate this using young female and male APOE3 and APOE4 targeted replacement mice. We also used APOE isogenic induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (iHLCs) to examine specific effects in a human-relevant cell model. Proteomic and functional assays show that APOE4 causes extensive changes to liver mitochondrial function in a sex-specific manner in mice and alters glucose and lipid metabolism. APOE4 also impairs mitochondrial function in iHLCs and shifts metabolism towards glycolysis while modifying expression of extracellular matrix proteins. Additionally, APOE4 iHLCs display a greater reliance on fatty acids as an energy source and show increased lipid accumulation. Taken together, our findings show that APOE genetic variation causes mitochondrial dysfunction and rewires hepatic metabolism.