Dictyostelium cell death: early emergence and demise of highly polarized paddle cells.
Cell death in the stalk of Dictyostelium discoideum, a prototypic vacuolar cell death, can be studied in vitro using cells differentiating as a monolayer. To identify early events, we examined potentially dying cells at a time when the classical signs of Dictyostelium cell death, such as heavy vacuolization and membrane lesions, were not yet apparent. We observed that most cells proceeded through a stereotyped series of differentiation stages, including the emergence of "paddle" cells showing high motility and strikingly marked subcellular compartmentalization with actin segregation. Paddle cell emergence and subsequent demise with paddle-to-round cell transition may be critical to the cell death process, as they were contemporary with irreversibility assessed through time-lapse videos and clonogenicity tests. Paddle cell demise was not related to formation of the cellulose shell because cells where the cellulose-synthase gene had been inactivated underwent death indistinguishable from that of parental cells. A major subcellular alteration at the paddle-to-round cell transition was the disappearance of F-actin. The Dictyostelium vacuolar cell death pathway thus does not require cellulose synthesis and includes early actin rearrangements (F-actin segregation, then depolymerization), contemporary with irreversibility, corresponding to the emergence and demise of highly polarized paddle cells.
Levraud
Jean-Pierre
JP
Centre d'Immunologie de Marseille-Luminy, INSERM/CNRS, Case 906, Parc Scientifique de Luminy, 13288 Marseille Cedex 9, France.
Adam
Myriam
M
Luciani
Marie-Françoise
MF
de Chastellier
Chantal
C
Blanton
Richard L
RL
Golstein
Pierre
P
D000199:Actins / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins / Q000494:pharmacology; D002451:Cell Compartmentation; D002465:Cell Movement / Q000187:drug effects; D016764:Cell Polarity; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D004023:Dictyostelium / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D015801:Helminth Proteins / Q000494:pharmacology; D006588:Hexanones; D006843:Hydrocarbons, Chlorinated; D007425:Intracellular Membranes / Q000648:ultrastructure; D011506:Proteins; D015800:Protozoan Proteins / Q000494:pharmacology; D011554:Pseudopodia / Q000187:drug effects; D013217:Starvation / Q000378:metabolism
D000199:Actins; D029742:Caenorhabditis elegans Proteins; D002352:Carrier Proteins; C490570:Differentiation-inducing factor-1, Dictyostelium; D015801:Helminth Proteins; D006588:Hexanones; D006843:Hydrocarbons, Chlorinated; D011506:Proteins; D015800:Protozoan Proteins