Fig. 8.

Putative models of the role of sorting nexin-4 (SNX4) role in β-site amyloid precursor protein-cleaving enzyme 1 (BACE1) trafficking. a BACE1 in the plasma membrane is endocytosed and trafficked to the sorting endosomes. BACE1 is then sorted to the late endosomes and lysosomes for degradation. If BACE1 interacts with SNX4 during the sorting processes, it is recycled to the plasma membrane by SNX4 and shifted away from the lysosomal degradation pathway, resulting in a longer half-life and more chances to generate β-amyloid. b When SNX4 is upregulated, such as in the early stage in Alzheimer’s disease model mice, SNX4 recycles BACE1 and prevents its degradation. c When SNX4 is downregulated, the recycling of BACE1 is decreased, and its degradation increases