Fig. 3
From: Apolipoprotein E in Alzheimer’s disease: molecular insights and therapeutic opportunities
ApoE biology in the brain. ApoE is mainly expressed by astrocytes in the brain. Upon expression, apoE is lipidated mainly by the ABCA1 transporter, which is located at the plasma membrane of astrocytes and ABCG1, which is present on the plasma membrane of astrocytes and neurons. Secreted apoE binds to different receptors expressed on neurons (and other cells) that are involved in endocytosis (LDLR, LRP1, HSPG) or signaling (apoER2, VLDLR) and affects endosomal trafficking and receptor recycling to the plasma membrane. ApoE is also required for the transport of excess oxidized fatty acids that are generated during neuronal activity to astrocytes, which are either stored in lipid droplets or used for energy production via β-oxidation