Limits...
Dictyostelium cell death: early emergence and demise of highly polarized paddle cells.

Levraud JP, Adam M, Luciani MF, de Chastellier C, Blanton RL, Golstein P - J. Cell Biol. (2003)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Centre d'Immunologie de Marseille-Luminy, INSERM/CNRS, Case 906, Parc Scientifique de Luminy, 13288 Marseille Cedex 9, France.

ABSTRACT
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.

Show MeSH
Paddle cells, social behavior, and parapodia. (a) A paddle cell on the move 13 h after addition of DIF-1; six images taken 15 s apart. The paddle cell is first moving upwards, then turning to the right. Propodium at the upper part of the cell, then moving to the right. Parapodium first barely visible, then becoming evident, here at the posterior part of the cell. (b) Several paddle cells forming a transient rosette 13 h after addition of DIF-1; three images taken 30 s apart. The third image shows departing paddle cells, with barely visible posterior parapodia. (c) Several paddle cells moving in single line 15 h after addition of DIF-1; five images taken 5 s apart. Parapodia can be seen, first between the upper cell and the second one, then between the second and the third one.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2172757&req=5

fig3: Paddle cells, social behavior, and parapodia. (a) A paddle cell on the move 13 h after addition of DIF-1; six images taken 15 s apart. The paddle cell is first moving upwards, then turning to the right. Propodium at the upper part of the cell, then moving to the right. Parapodium first barely visible, then becoming evident, here at the posterior part of the cell. (b) Several paddle cells forming a transient rosette 13 h after addition of DIF-1; three images taken 30 s apart. The third image shows departing paddle cells, with barely visible posterior parapodia. (c) Several paddle cells moving in single line 15 h after addition of DIF-1; five images taken 5 s apart. Parapodia can be seen, first between the upper cell and the second one, then between the second and the third one.

Mentions: Paddle cells exhibit a marked social behavior, i.e., they often associate in (labile) rosettes (Fig. 3 b and Video 4) and in (less labile) cell chains (Fig. 3 c and Videos 5 and 6). This behavior is due at least in part to the existence in each paddle cell of an adhesive lateral or posterior “hook” that we call parapodium. The parapodium can be seen trailing behind some moving paddle cells (Fig. 3 a and Videos 2–4) or linking cells in chains (Fig. 3 c and Videos 5 and 6) or to the substrate (Video 7). From the examination of paddle cells in a number of videos, we feel that the social behavior of paddle cells may also entail a degree of cytotropism: paddle cells seem to head for, collide, and associate with other cells perhaps more readily than one would expect from chance alone. Whether this is related to chemotactism, and for what, is not known.


Dictyostelium cell death: early emergence and demise of highly polarized paddle cells.

Levraud JP, Adam M, Luciani MF, de Chastellier C, Blanton RL, Golstein P - J. Cell Biol. (2003)

Paddle cells, social behavior, and parapodia. (a) A paddle cell on the move 13 h after addition of DIF-1; six images taken 15 s apart. The paddle cell is first moving upwards, then turning to the right. Propodium at the upper part of the cell, then moving to the right. Parapodium first barely visible, then becoming evident, here at the posterior part of the cell. (b) Several paddle cells forming a transient rosette 13 h after addition of DIF-1; three images taken 30 s apart. The third image shows departing paddle cells, with barely visible posterior parapodia. (c) Several paddle cells moving in single line 15 h after addition of DIF-1; five images taken 5 s apart. Parapodia can be seen, first between the upper cell and the second one, then between the second and the third one.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2172757&req=5

fig3: Paddle cells, social behavior, and parapodia. (a) A paddle cell on the move 13 h after addition of DIF-1; six images taken 15 s apart. The paddle cell is first moving upwards, then turning to the right. Propodium at the upper part of the cell, then moving to the right. Parapodium first barely visible, then becoming evident, here at the posterior part of the cell. (b) Several paddle cells forming a transient rosette 13 h after addition of DIF-1; three images taken 30 s apart. The third image shows departing paddle cells, with barely visible posterior parapodia. (c) Several paddle cells moving in single line 15 h after addition of DIF-1; five images taken 5 s apart. Parapodia can be seen, first between the upper cell and the second one, then between the second and the third one.
Mentions: Paddle cells exhibit a marked social behavior, i.e., they often associate in (labile) rosettes (Fig. 3 b and Video 4) and in (less labile) cell chains (Fig. 3 c and Videos 5 and 6). This behavior is due at least in part to the existence in each paddle cell of an adhesive lateral or posterior “hook” that we call parapodium. The parapodium can be seen trailing behind some moving paddle cells (Fig. 3 a and Videos 2–4) or linking cells in chains (Fig. 3 c and Videos 5 and 6) or to the substrate (Video 7). From the examination of paddle cells in a number of videos, we feel that the social behavior of paddle cells may also entail a degree of cytotropism: paddle cells seem to head for, collide, and associate with other cells perhaps more readily than one would expect from chance alone. Whether this is related to chemotactism, and for what, is not known.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Centre d'Immunologie de Marseille-Luminy, INSERM/CNRS, Case 906, Parc Scientifique de Luminy, 13288 Marseille Cedex 9, France.

ABSTRACT
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.

Show MeSH