The Cytosolic Adaptor AP-1A Is Essential for the Trafficking and Function of Niemann-Pick Type C Proteins

Authors

  • Steve Poirier,

    1. Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montréal, QC, Canada
    2. Laboratory of Molecular Cell Biology, Montreal Heart Institute, Montréal, QC, Canada
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    • These authors contributed equally to this work.

  • Gaétan Mayer,

    1. Laboratory of Molecular Cell Biology, Montreal Heart Institute, Montréal, QC, Canada
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    • These authors contributed equally to this work.

  • Stephanie R. Murphy,

    1. Department of Biochemistry, Dartmouth Medical School, Hanover, NH, USA
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    • These authors contributed equally to this work.

  • William S. Garver,

    1. Department of Biochemistry and Molecular Biology, The University of New Mexico, Albuquerque, NM, USA
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  • Ta Yuan Chang,

    1. Department of Biochemistry, Dartmouth Medical School, Hanover, NH, USA
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  • Peter Schu,

    Corresponding author
    1. Center for Biochemistry and Molecular Cell Biology, Georg-August-Universität Göttingen, Göttingen, Germany
    • Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montréal, QC, Canada
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  • Nabil G. Seidah

    Corresponding author
    • Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal, Montréal, QC, Canada
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Corresponding author: Nabil G. Seidah, seidahn@ircm.qc.ca and Peter Schu, pschu@gwdg.de

Abstract

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.

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