As is the case for most metazoans, C. elegans cells have the potential to undergo developmental cell death (programmed cell death) or a necrotic-like death in response to cell injury. Analysis of mutations that disrupt the reproducible pattern of cell death that occurs during C. elegans development has defined a genetic pathway for programmed cell death. This program involves the activities of certain genes, such as
ces-1 and the
ces-2 bZIP transcription factor, which regulate the life/death decision in specific subsets of cells.
ced-9, a Bcl-2 family member, acts globally to negatively regulate the activities of
ced-4S (which promotes cell death) and
ced-4L, which promotes cell life.
ced-3 encodes a member of the ICE cysteine protease family that is essential for execution of all programmed cell deaths. Once cells die, corpses are phagocytized and consumed in what appear to be at least two parallel pathways that require the activities of
ced-1,
ced-6,
ced-7 and
ced-2,
ced-5,
ced-10. Degradation of corpse DNA requires the product of the
nuc-1 gene. Degenerative cell death, characterized by cell swelling, can be induced by different cell injuries including that conferred by mutant degenerin ion channels (encoded by
deg-1,
mec-4,
mec-10 and
unc-8) and by expression of human beta-amyloid peptide. Remarkable parallels between nematode and mammalian death programs have advanced understanding of human cell death mechanisms.