The cytosolic adaptor AP-1A is essential for the trafficking and function of Niemann-Pick type C proteins.
Niemann-Pick type C (NPC) disease is a fatal neurodegenerative disorder characterized by over-accumulation of low-density lipoprotein-derived cholesterol and glycosphingolipids in late endosomes/lysosomes (LE/L) throughout the body. Human mutations in either NPC1 or NPC2 genes have been directly associated with impaired cholesterol efflux from LE/L. Independent from its role in cholesterol homeostasis and its NPC2 partner, NPC1 was unexpectedly identified as a critical player controlling intracellular entry of filoviruses such as Ebola. In this study, a yeast three-hybrid system revealed that the NPC1 cytoplasmic tail directly interacts with the clathrin adaptor protein AP-1 via its acidic/di-leucine motif. Consequently, a nonfunctional AP-1A cytosolic complex resulted in a typical NPC-like phenotype mainly due to a direct impairment of NPC1 trafficking to LE/L and a partial secretion of NPC2. Furthermore, the mislocalization of NPC1 was not due to cholesterol accumulation in LE/L, as it was not rescued upon treatment with Mβ-cyclodextrin, which almost completely eliminated intracellular free cholesterol. Our cumulative data demonstrate that the cytosolic clathrin adaptor AP-1A is essential for the lysosomal targeting and function of NPC1 and NPC2.
Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montréal, QC, Canada.
Steve
S
Poirier
Gaétan
G
Mayer
Stephanie R
SR
Murphy
William S
WS
Garver
Ta Yuan
TY
Chang
Peter
P
Schu
Nabil G
NG
Seidah
D033961:Adaptor Protein Complex 1 / Q000378:metabolism*; D020816:Amino Acid Motifs; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism; D005089:Exocytosis; D047908:Intracellular Signaling Peptides and Proteins; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D000077296:Niemann-Pick C1 Protein; D054730:Protein Interaction Domains and Motifs; D021381:Protein Transport; D020798:Two-Hybrid System Techniques; D033921:Vesicular Transport Proteins / Q000378:metabolism*; D047392:beta-Cyclodextrins / Q000494:pharmacology
D033961:Adaptor Protein Complex 1; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; C106881:NPC1 protein, human; D000077296:Niemann-Pick C1 Protein; C497045:Npc2 protein, mouse; D033921:Vesicular Transport Proteins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol