How the worm removes corpses: the nematode C. elegans as a model system to study engulfment

Abstract

Apoptotic cell death in the nematode C. elegans culminates with the removal of the dying cells from the organism. This removal is brought forth through a rapid and specific engulfment of the doomed cell by one of its neighbors. Over half a dozen genes have been identified that function in this process in the worm. Many of these engulfment genes have functional homologs in Drosophila and higher vertebrates. Indeed, there is growing evidence supporting the hypothesis that the pathways that mediate the removal of apoptotic cells might be, at least in part, conserved through evolution. Cell Death and Differentiation (2001) 8, 564 ± 568.

The Presumptive Phosphatidylserine Receptor Is Dispensable for Innate Anti-inflammatory Recognition and Clearance of Apoptotic Cells

“…These gene products function in redundant pathways for the clearance of dead cells (23), and their orthologues have been implicated in the clearance of dead cells in mammals (24). Significantly, these pathways converge to activate the small GTPase Rac1, the mammalian Ced10 equivalent, involved in cytoskeletal rearrangement and process extension (25,26).…”

Draper-mediated and Phosphatidylserine-independent Phagocytosis of Apoptotic Cells by Drosophila Hemocytes/Macrophages

“…However, the nature of receptors that exist farthest upstream of these pathways has been unknown until recently. In C. elegans, CED-1 has been suggested to serve as a receptor for one pathway that involves CED-6, CED-7, and CED-10, although the cognate ligand remains to be identified (14,23). Surface receptors responsible for the other pathway (which involves CED-2, CED-5, CED-10, and CED-12) may include PSR-1, which is encoded by psr-1, the C. elegans homologue of the gene coding for the macrophage PS receptor (25).…”

The c-Jun kinase signaling cascade promotes glial engulfment activity through activation of draper and phagocytic function

“…The presence of cell corpses and cellular debris triggers rapid responses from neighboring professional or non-professional phagocytes, ultimately promoting corpse engulfment. [1][2][3] In the central nervous system (CNS) glial cells are the primary immune cell type, constantly surveying the neural environment for signs of cell death or injury. Neural injury results in rapid changes in glial cellular phenotypes -glia become 'reactive' whereby they exhibit dramatic changes in morphology and patterns of gene expression and they ultimately phagocytose degenerating neuronal debris.…”