First published online March 9, 2006
Development 133, 703e (2006)
© The Company of Biologists Limited
Signal changes for Dicty Rb
When starved, Dictyostelium amoebae differentiate into either
spores or stalk cells. This decision partly depends on the cell-cycle status
of a cell at the time of starvation. MacWilliams and co-workers now report
that rblA, the Dictyostelium orthologue of the
retinoblastoma susceptibility gene Rb, controls stalk/spore
preference (see p.
1287). They show that,
during growth, rblA expression correlates with factors that favour
spore formation (late cell-cycle position, good nutrition) and that it
increases 200-fold in differentiating spores. rblA-null strains show
a strong preference for stalk formation when mixed with wild-type cells and
are hypersensitive to the stalk morphogen DIF in vitro, indicating that
rblA suppresses the DIF response in cells destined to be spores.
However, rblA is not important for the Dictyostelium cell
cycle. As Rb is required for both differentiation and cell-cycle exit
in plants and animals, the researchers propose that Dictyostelium has
retained the differentiation-Rb link but has lost the
Rb-cell-cycle exit link to avoid shunting starving cells into the
spore pathway.
Related articles in Development:
- A retinoblastoma ortholog controls stalk/spore preference in Dictyostelium
- Harry MacWilliams, Kimchi Doquang, Roberto Pedrola, Gytha Dollman, Daniela Grassi, Thomas Peis, Adrian Tsang, and Adriano Ceccarelli
Development 2006 133: 1287-1297.
[Abstract]
[Full Text]
