title: Programmed cell clearance: From nematodes to humans.
abstract: Programmed cell clearance is a highly regulated physiological process of elimination of dying cells that occurs rapidly and efficiently in healthy organisms. It thus ensures proper development as well as homeostasis. Recent studies have disclosed a considerable degree of conservation of cell clearance pathways between nematodes and higher organisms. The externalization of the anionic phospholipid phosphatidylserine (PS) has emerged as an important "eat-me" signal for phagocytes and its exposition on apoptotic cells is controlled by phospholipid translocases and scramblases. However, there is mounting evidence that PS exposure occurs not only in apoptosis, but may also be actively expressed on the surface of cells undergoing other forms of cell death including necrosis; PS is also expressed on the surface of engulfing cells. Additionally, PS may act as a "save-me" signal during axonal regeneration. Here we discuss mechanisms of PS exposure and its recognition by phagocytes as well as the consequences of PS signaling in nematodes and in mammals.
authors.affiliation: Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, 17177, Stockholm, Sweden.
authors.forename: Katharina
authors.initials: K
authors.lastname: Klöditz
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA.
authors.forename: Yu-Zen
authors.initials: YZ
authors.lastname: Chen
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, 80309, USA.
authors.forename: Ding
authors.initials: D
authors.lastname: Xue
authors.affiliation: Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, 17177, Stockholm, Sweden. Electronic address: Bengt.Fadeel@ki.se.
authors.forename: Bengt
authors.initials: B
authors.lastname: Fadeel
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D017173:Caenorhabditis elegans / Q000166:cytology / Q000378:metabolism; D016923:Cell Death / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D010586:Phagocytes / Q000502:physiology*; D010587:Phagocytosis / Q000502:physiology; D010718:Phosphatidylserines / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: D010718:Phosphatidylserines
keywords: Axonal fusion; C. elegans; Engulfment; Phosphatidylserine; Scramblases; Translocases