Identification of two evolutionarily conserved genes regulating processing of engulfed apoptotic cells

Nature. 2010 Apr 1;464(7289):778-82. doi: 10.1038/nature08853. Epub 2010 Mar 21.


Engulfment of apoptotic cells occurs throughout life in multicellular organisms. Impaired apoptotic cell clearance (due to defective recognition, internalization or degradation) results in autoimmune disease. One fundamental challenge in understanding how defects in corpse removal translate into diseased states is the identification of critical components orchestrating the different stages of engulfment. Here we use genetic, cell biological and molecular studies in Caenorhabditis elegans and mammalian cells to identify SAND-1 and its partner CCZ-1 as new factors in corpse removal. In worms deficient in either sand-1 or ccz-1, apoptotic cells are internalized and the phagosomes recruit the small GTPase RAB-5 but fail to progress to the subsequent RAB-7(+) stage. The mammalian orthologues of SAND-1, namely Mon1a and Mon1b, were similarly required for phagosome maturation. Mechanistically, Mon1 interacts with GTP-bound Rab5, identifying Mon1 as a previously unrecognized Rab5 effector. Moreover, a Mon1-Ccz1 complex (but not either protein alone) could bind Rab7 and could also influence Rab7 activation, suggesting Mon1-Ccz1 as an important link in progression from the Rab5-positive stage to the Rab7-positive stage of phagosome maturation. Taken together, these data identify SAND-1 (Mon1) and CCZ-1 (Ccz1) as critical and evolutionarily conserved components regulating the processing of ingested apoptotic cell corpses.

Publication types

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

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Apoptosis / genetics*
  • Caenorhabditis elegans / cytology
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cell Line
  • Conserved Sequence / genetics*
  • Disorders of Sex Development
  • Evolution, Molecular*
  • Gonads / cytology
  • Gonads / metabolism
  • Guanine Nucleotide Dissociation Inhibitors / metabolism
  • Hydrogen-Ion Concentration
  • Intracellular Signaling Peptides and Proteins
  • Mice
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / metabolism
  • NIH 3T3 Cells
  • Phagocytosis / genetics*
  • Phagosomes / genetics
  • Phagosomes / metabolism
  • Protein Binding
  • Thymus Gland / cytology
  • Two-Hybrid System Techniques
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism*
  • rab GTP-Binding Proteins / metabolism
  • rab5 GTP-Binding Proteins / metabolism
  • rab7 GTP-Binding Proteins


  • CCZ-1 protein, C elegans
  • Caenorhabditis elegans Proteins
  • Carrier Proteins
  • Guanine Nucleotide Dissociation Inhibitors
  • Intracellular Signaling Peptides and Proteins
  • Mon1a protein, mouse
  • Mon1b protein, mouse
  • Multiprotein Complexes
  • SAND-1 protein, C elegans
  • Vesicular Transport Proteins
  • rab7 GTP-Binding Proteins
  • rab7 GTP-binding proteins, mouse
  • rab GTP-Binding Proteins
  • rab5 GTP-Binding Proteins