Basolateral sorting and transcytosis define the Cu+-regulated translocation of ATP7B to the bile canaliculus

• Published in: Journal of cell science Vol. 129; no. 11; pp. 2190 - 2201
• Main Authors: Lalioti, Vasiliki, Peiró, Ramón, Pérez-Berlanga, Manuela, Tsuchiya, Yo, Muñoz, Angeles, Villalba, Teresa, Sanchez, Carlos, Sandoval, Ignacio V.
• Format: Journal Article
• Language: English
• Published: England 01.06.2016
• Subjects: Adenosine Triphosphatases - metabolism; Animals; Bile Canaliculi - drug effects; Bile Canaliculi - metabolism; Brefeldin A - pharmacology; Cation Transport Proteins - metabolism; Cell Compartmentation - drug effects; Cell Membrane - drug effects; Cell Membrane - metabolism; Copper - pharmacology; Copper-transporting ATPases; Guanine Nucleotide Exchange Factors - metabolism; Hep G2 Cells; Humans; Hydrazones - pharmacology; Lysosomes - drug effects; Lysosomes - metabolism; Macrolides - pharmacology; Microtubules - drug effects; Microtubules - metabolism; Protein Transport - drug effects; Rats; Secretory Vesicles - drug effects; Secretory Vesicles - metabolism; trans-Golgi Network - drug effects; trans-Golgi Network - metabolism; Transcytosis - drug effects; TGN; Transcytosis; ATP7B; Copper; Bile canaliculus; Trafficking
• ISSN: 0021-9533; 1477-9137; 1477-9137
• DOI: 10.1242/jcs.184663

The Cu+ pump ATP7B plays an irreplaceable role in the elimination of excess Cu+ by the hepatocyte into the bile. The trafficking and site of action of ATP7B are subjects of controversy. One current proposal is that an increase in intracellular Cu+ results in the translocation of ATP7B to the lysosomes and excretion of excess Cu+ through lysosomal-mediated exocytosis at the bile canaliculus. Here, we show that ATP7B is transported from the trans-Golgi network (TGN) to the bile canaliculus by basolateral sorting and endocytosis, and microtubule-mediated transcytosis through the subapical compartment. Trafficking ATP7B is not incorporated into lysosomes, and addition of Cu+ does not cause relocalization of lysosomes and the appearance of lysosome markers in the bile canaliculus. Our data reveal the pathway of the Cu+-mediated transport of ATP7B from the TGN to the bile canaliculus and indicates that the bile canaliculus is the primary site of ATP7B action in the elimination of excess Cu+.