The Menkes disease ATPase (ATP7A) is internalized via a Rac1-regulated, clathrin- and caveolae-independent pathway

Hum Mol Genet. 2003 Jul 1;12(13):1523-33. doi: 10.1093/hmg/ddg166.

Abstract

The Menkes disease gene encodes a P-type transmembrane ATPase (ATP7A) that translocates cytosolic copper ions across intracellular membranes of compartments along the secretory pathway. ATP7A moves from the trans-Golgi network (TGN) to the cell surface in response to exogenously added copper ions and recycles back to the TGN upon copper removal. The protein contains a C-terminal di-leucine motif necessary for internalization from the cell surface. In this study we show that ATP7A is internalized by a novel pathway that is independent of clathrin-mediated endocytosis. Expression of dominant-negative mutants of the dynamin-I, dynamin-II and Eps15 proteins that block clathrin-dependent endocytosis of the transferrin receptor do not inhibit internalization of endogenous ATP7A, or an ATP7A reporter molecule (CD8-MCF1). Similarly, inhibitors of caveolae-mediated uptake do not affect ATP7A internalization whilst preventing uptake of PODIPY-ganglioside GM(1), a caveolae marker. In contrast, expression of a constitutively active mutant of the Rac1 GTPase inhibits plasma membrane internalization of both the ATP7A and transferrin receptor transmembrane proteins. These findings define a novel route required for ATP7A internalization and delivery to endosomes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / metabolism*
  • Adenosine Triphosphatases / physiology
  • Amino Acid Motifs
  • Animals
  • Boron Compounds / pharmacology
  • COS Cells
  • Cation Transport Proteins / metabolism*
  • Cation Transport Proteins / physiology
  • Caveolae / metabolism*
  • Cell Membrane / metabolism
  • Clathrin / metabolism*
  • Copper / metabolism
  • Copper-Transporting ATPases
  • Cytosol / metabolism
  • Endocytosis
  • Endosomes / metabolism
  • Genes, Dominant
  • Green Fluorescent Proteins
  • HeLa Cells
  • Humans
  • Ions
  • Leucine / chemistry
  • Luminescent Proteins / metabolism
  • Menkes Kinky Hair Syndrome / genetics*
  • Microscopy, Fluorescence
  • Models, Biological
  • Mutation
  • Protein Structure, Tertiary
  • Receptors, Transferrin / metabolism
  • Recombinant Fusion Proteins / metabolism*
  • Recombinant Fusion Proteins / physiology
  • Temperature
  • Time Factors
  • Transfection
  • rac1 GTP-Binding Protein / metabolism*
  • trans-Golgi Network / metabolism

Substances

  • 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene
  • Boron Compounds
  • Cation Transport Proteins
  • Clathrin
  • Ions
  • Luminescent Proteins
  • Receptors, Transferrin
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • Copper
  • Adenosine Triphosphatases
  • rac1 GTP-Binding Protein
  • ATP7A protein, human
  • Copper-Transporting ATPases
  • Leucine