Niemann-Pick C1 protein transports copper to the secretory compartment from late endosomes where ATP7B resides.
Wilson disease is a genetic disorder characterized by the accumulation of copper in the body by defective biliary copper excretion. Wilson disease gene product (ATP7B) functions in copper incorporation to ceruloplasmin (Cp) and biliary copper excretion. However, copper metabolism in hepatocytes has been still unclear. Niemann-Pick disease type C (NPC) is a lipid storage disorder and the most commonly mutated gene is NPC1 and its gene product NPC1 is a late endosome protein and regulates intracellular vesicle traffic. In the present study, we induced NPC phenotype and examined the localization of ATP7B and secretion of holo-Cp, a copper-binding mature form of Cp. The vesicle traffic was modulated using U18666A, which induces NPC phenotype, and knock down of NPC1 by RNA interference. ATP7B colocalized with the late endosome markers, but not with the trans-Golgi network markers. U18666A and NPC1 knock down decreased holo-Cp secretion to culture medium, but did not affect the secretion of other secretory proteins. Copper accumulated in the cells after the treatment with U18666A. These findings suggest that ATP7B localizes in the late endosomes and that copper in the late endosomes is transported to the secretory compartment via NPC1-dependent pathway and incorporated into apo-Cp to form holo-Cp.
Yanagimoto
Chikatoshi
C
Division of Gastroenterology, Department of Medicine and Research Center for Innovative Cancer Therapy of the 21st Century COE Program for Medical Science, Kurume University School of Medicine, Kurume, Japan. yanagimoto_chikatoshi@kurume-u.ac.jp
Harada
Masaru
M
Kumemura
Hiroto
H
Koga
Hironori
H
Kawaguchi
Takumi
T
Terada
Kunihiko
K
Hanada
Shinichiro
S
Taniguchi
Eitaro
E
Koizumi
Yukio
Y
Koyota
Souichi
S
Ninomiya
Haruaki
H
Ueno
Takato
T
Sugiyama
Toshihiro
T
Sata
Michio
M
D033982:Adaptor Protein Complex gamma Subunits / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000736:Androstenes / Q000494:pharmacology; D000924:Anticholesteremic Agents / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002570:Ceruloplasmin / Q000378:metabolism; D003300:Copper / Q000378:metabolism*; D000073840:Copper-Transporting ATPases; D011992:Endosomes / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D000077296:Niemann-Pick C1 Protein; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000090802:rab7 GTP-Binding Proteins
D033982:Adaptor Protein Complex gamma Subunits; D000736:Androstenes; D000924:Anticholesteremic Agents; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D047908:Intracellular Signaling Peptides and Proteins; C497811:LAMP2 protein, human; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; C106881:NPC1 protein, human; D000077296:Niemann-Pick C1 Protein; D034741:RNA, Small Interfering; D000090802:rab7 GTP-Binding Proteins; C006261:3-beta-(2-(diethylamino)ethoxy)androst-5-en-17-one; D003300:Copper; D002570:Ceruloplasmin; D000251:Adenosine Triphosphatases; D020691:rab GTP-Binding Proteins; C000612464:ATP7B protein, human; D000073840:Copper-Transporting ATPases