The P4-ATPase ATP9A is a novel determinant of exosome release

PLoS One. 2019 Apr 4;14(4):e0213069. doi: 10.1371/journal.pone.0213069. eCollection 2019.


Extracellular vesicles (EVs) released by cells have a role in intercellular communication to regulate a wide range of biological processes. Two types of EVs can be recognized. Exosomes, which are released from multi-vesicular bodies upon fusion with the plasma membrane, and ectosomes, which directly bud from the plasma membrane. How cells regulate the quantity of EV release is largely unknown. One of the initiating events in vesicle biogenesis is the regulated transport of phospholipids from the exoplasmic to the cytosolic leaflet of biological membranes. This process is catalyzed by P4-ATPases. The role of these phospholipid transporters in intracellular vesicle transport has been established in lower eukaryotes and is slowly emerging in mammalian cells. In Caenorhabditis elegans (C. elegans), deficiency of the P4-ATPase member TAT-5 resulted in enhanced EV shedding, indicating a role in the regulation of EV release. In this study, we investigated whether the mammalian ortholog of TAT-5, ATP9A, has a similar function in mammalian cells. We show that knockdown of ATP9A expression in human hepatoma cells resulted in a significant increase in EV release that was independent of caspase-3 activation. Pharmacological blocking of exosome release in ATP9A knockdown cells did significantly reduce the total number of EVs. Our data support a role for ATP9A in the regulation of exosome release from human cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / genetics*
  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans Proteins / genetics
  • Caspase 3 / genetics
  • Cell Communication / genetics
  • Cell Membrane / genetics
  • Cell-Derived Microparticles / genetics
  • Endocytosis / genetics
  • Exosomes / genetics*
  • Extracellular Vesicles / genetics*
  • Extracellular Vesicles / metabolism
  • Gene Expression Regulation
  • Hep G2 Cells
  • Humans
  • Membrane Transport Proteins / genetics*
  • Phospholipids / metabolism
  • Protein Transport / genetics


  • Caenorhabditis elegans Proteins
  • Membrane Transport Proteins
  • Phospholipids
  • Caspase 3
  • Adenosine Triphosphatases
  • TAT-5 protein, C elegans
  • ATP9A protein, human

Grants and funding

Project was funded by Academisch Medisch centrum (AMC), Amsterdam.