Afm. Maree et P. Hogeweg, How amoeboids self-organize into a fruiting body: Multicellular coordination in Dictyostelium discoideum, P NAS US, 98(7), 2001, pp. 3879-3883
Citations number
29
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
When individual amoebae of the cellular slime mold Dictyostelium discoideum
are starving, they aggregate to form a multicellular migrating slug, which
moves toward a region suitable for culmination. The culmination of the mor
phogenesis involves complex cell movements that transform a mound of cells
into a globule of spores on a slender stalk. The movement has been likened
to a "reverse fountain," whereby prestalk cells in the upper part form a st
alk that moves downwards and anchors to the substratum. while prespore cell
s in the lower part move upwards to form the spore head. So far, however, n
o satisfactory explanation has been produced for this process. Using a comp
uter simulation that we developed, we now demonstrate that the processes th
at are essential during the earlier stages of the morphogenesis are in fact
sufficient to produce the dynamics of the culmination stage. These process
es are cAMP signaling, differential adhesion, cell differentiation, and pro
duction of extracellular matrix. Our model clarifies the processes that gen
erate the observed cell movements. More specifically, we show that periodic
upward movements, caused by chemotactic motion, are essential for successf
ul culmination, because the pressure waves they induce squeeze the stalk do
wnwards through the cell mass. The mechanisms revealed by our model have a
number of self-organizing and self-correcting properties and can account fo
r many previously unconnected and unexplained experimental observations.