First published online January 12, 2006
Development 133, 304e (2006)
© The Company of Biologists Limited
DimB light illuminates Dicty development
Dictyostelium is a powerful model system in which to study
developmental decision making, as illustrated by two new papers that report
that DimB, a bZIP transcription factor, directly regulates the responses of
Dictyostelium amoebae to the differentiation factor DIF-1. On
starvation, Dictyostelium amoebae aggregate and form a migrating
slug. During this process, they differentiate into prestalk (pst) or prespore
cells. pstA cells occupy the tip of the slug, while pstO cells lie behind the
tip and prespore cells occupy the rear four-fifths. DIF-1, which is made by
prespore cells, is required for the differentiation of pstO cells, but its
signal transduction pathway is largely unknown. Now, two groups report that
DimB, a bZIP transcription factor, directly regulates DIF-1 responses in
Dictyostelium. Zhukovskaya et al. identified DimB by purifying
molecules that interact with two promoter elements in ecmA, a gene
expressed in prestalk cells (see
p. 439). They show that
DimB establishes a gradient of ecmA expression in the slug tip by
repressing its expression in cells at the rear and centre of the prestalk
zone, and suggest that competition between DimB and an unknown activator
controls ecmA expression. They also show that DimB accumulates in the
nucleus when cells are exposed to DIF-1 and becomes associated with the
ecmA promoter. Huang et al. used bioinformatics to identify DimB (see
p. 449). Their search
of the Dictyostelium genome for factors that could heterodimerize
with DimA – another bZIP transcription factor that regulates
Dictyostelium responses to DIF-1 – identified DimB. They show
that DimB interacts with DimA in vitro and that DIF-1 stimulation of cells
causes the rapid nuclear accumulation of both DimA and DimB. Together, these
papers provide new insights into how DIF-1 controls Dictyostelium
differentiation and draw parallels with mammalian systems, where interactions
between transcription factors increase their regulatory potential.
Related articles in Development:
- The Dictyostelium bZIP transcription factor DimB regulates prestalk-specific gene expression
- Natasha V. Zhukovskaya, Masashi Fukuzawa, Yoko Yamada, Tsuyoshi Araki, and Jeffrey G. Williams
Development 2006 133: 439-448.
[Abstract]
[Full Text]
- bZIP transcription factor interactions regulate DIF responses in Dictyostelium
- Eryong Huang, Simone L. Blagg, Thomas Keller, Mariko Katoh, Gad Shaulsky, and Christopher R. L. Thompson
Development 2006 133: 449-458.
[Abstract]
[Full Text]
