TRPV5 Is Internalized via Clathrin-dependent Endocytosis to Enter a Ca2+-controlled Recycling Pathway.

The epithelial Ca2+ channel TRPV5 plays an essential role in transcellular Ca2+ transport and is one of the most Ca2+-selective members of the transient receptor potential superfamily. Regulation of the abundance of TRPV5 at the cell surface is critical in body Ca2+ homeostasis. However, little is known about the mechanisms underlying TRPV5 endo- and exocytosis. Here, we show that TRPV5 is constitutively internalized in a dynamin- and clathrin-dependent manner. Internalized TRPV5 first appears in small vesicular structures and then localizes to perinuclear structures positive for Rab11a. TRPV5 has a half-life of more than 8 h and is stable even after internalization from the cell surface for more than 3 h. Disruption of cell surface delivery of newly synthesized TRPV5 by brefeldin A does not reduce TRPV5-mediated Ca2+ influx in cells, suggesting the presence of a stable intracellular pool of the channel capable of recycling back to the surface. Furthermore, the endocytic recycling kinetics is decreased upon treatment with Ca2+ chelator BAPTA-AM, indicating that the channel's trafficking pathways are dynamically controlled by Ca2+. [ABSTRACT FROM AUTHOR]