EFF-1 fusogen promotes phagosome sealing during cell process clearance in Caenorhabditis elegans

Nat Cell Biol. 2018 Apr;20(4):393-399. doi: 10.1038/s41556-018-0068-5. Epub 2018 Mar 19.


Phagocytosis of dying cells is critical in development and immunity1-3. Although proteins for recognition and engulfment of cellular debris following cell death are known4,5, proteins that directly mediate phagosome sealing are uncharacterized. Furthermore, whether all phagocytic targets are cleared using the same machinery is unclear. Degeneration of morphologically complex cells, such as neurons, glia and melanocytes, produces phagocytic targets of various shapes and sizes located in different microenvironments6,7. Thus, such cells offer unique settings to explore engulfment programme mechanisms and specificity. Here, we report that dismantling and clearance of a morphologically complex Caenorhabditis elegans epithelial cell requires separate cell soma, proximal and distal process programmes. Similar compartment-specific events govern the elimination of a C. elegans neuron. Although canonical engulfment proteins drive cell soma clearance, these are not required for process removal. We find that EFF-1, a protein previously implicated in cell-cell fusion 8 , specifically promotes distal process phagocytosis. EFF-1 localizes to phagocyte pseudopod tips and acts exoplasmically to drive phagosome sealing. eff-1 mutations result in phagocytosis arrest with unsealed phagosomes. Our studies suggest universal mechanisms for dismantling morphologically complex cells and uncover a phagosome-sealing component that promotes cell process clearance.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Video-Audio Media

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans / ultrastructure
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Death
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Mutation
  • Neurons / metabolism*
  • Neurons / pathology
  • Phagocytes / metabolism*
  • Phagocytes / ultrastructure
  • Phagocytosis*
  • Phagosomes / genetics
  • Phagosomes / metabolism*
  • Phagosomes / ultrastructure
  • Pseudopodia / genetics
  • Pseudopodia / metabolism*
  • Pseudopodia / ultrastructure
  • Signal Transduction


  • Caenorhabditis elegans Proteins
  • EFF-1 protein, C elegans
  • Membrane Glycoproteins