Live-cell imaging in Caenorhabditis elegans reveals the distinct roles of dynamin self-assembly and guanosine triphosphate hydrolysis in the removal of apoptotic cells

Mol Biol Cell. 2010 Feb 15;21(4):610-29. doi: 10.1091/mbc.e09-05-0440. Epub 2009 Dec 16.

Abstract

Dynamins are large GTPases that oligomerize along membranes. Dynamin's membrane fission activity is believed to underlie many of its physiological functions in membrane trafficking. Previously, we reported that DYN-1 (Caenorhabditis elegans dynamin) drove the engulfment and degradation of apoptotic cells through promoting the recruitment and fusion of intracellular vesicles to phagocytic cups and phagosomes, an activity distinct from dynamin's well-known membrane fission activity. Here, we have detected the oligomerization of DYN-1 in living C. elegans embryos and identified DYN-1 mutations that abolish DYN-1's oligomerization or GTPase activities. Specifically, abolishing self-assembly destroys DYN-1's association with the surfaces of extending pseudopods and maturing phagosomes, whereas inactivating guanosine triphosphate (GTP) binding blocks the dissociation of DYN-1 from these membranes. Abolishing the self-assembly or GTPase activities of DYN-1 leads to common as well as differential phagosomal maturation defects. Whereas both types of mutations cause delays in the transient enrichment of the RAB-5 GTPase to phagosomal surfaces, only the self-assembly mutation but not GTP binding mutation causes failure in recruiting the RAB-7 GTPase to phagosomal surfaces. We propose that during cell corpse removal, dynamin's self-assembly and GTP hydrolysis activities establish a precise dynamic control of DYN-1's transient association to its target membranes and that this control mechanism underlies the dynamic recruitment of downstream effectors to target membranes.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Animals, Genetically Modified
  • Apoptosis / physiology*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Caenorhabditis elegans* / cytology
  • Caenorhabditis elegans* / embryology
  • Caenorhabditis elegans* / physiology
  • Cell Membrane / metabolism
  • Dynamins / chemistry
  • Dynamins / genetics
  • Dynamins / metabolism*
  • Guanosine Triphosphate / metabolism*
  • Humans
  • Molecular Sequence Data
  • Mutation
  • Phagosomes / metabolism
  • Phagosomes / ultrastructure
  • Protein Structure, Tertiary
  • Rats
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism
  • rab5 GTP-Binding Proteins / genetics
  • rab5 GTP-Binding Proteins / metabolism

Substances

  • Caenorhabditis elegans Proteins
  • Recombinant Fusion Proteins
  • rab7 protein
  • Guanosine Triphosphate
  • rab GTP-Binding Proteins
  • rab5 GTP-Binding Proteins
  • Dynamins