Sorting nexin 17 accelerates internalization yet retards degradation of P-selectin

The transient appearance of P-Selectin on the surface of endothelial cells helps recruit leukocytes into sites of inflammation. The tight control of cell surface P-Selectin on these cells depends on regulated exocytosis of Weibel-Palade bodies where the protein is stored and on its rapid endocytosis. After endocytosis, P-Selectin is either sorted via endosomes and the Golgi apparatus for storage in Weibel-Palade bodies or targeted to lysosomes for degradation. A potential player in this complex endocytic itinerary is SNX17, a member of the sorting nexin family, which has been shown in a yeast two-hybrid assay to bind P-Selectin. Here, we show that overexpression of SNX17 in mammalian cells can influence two key steps in the endocytic trafficking of P-Selectin. First, it promotes the endocytosis of P-Selectin from the plasma membrane. Second, it inhibits the movement of P-Selectin into lysosomes, thereby reducing its degradation.