Iv. Wijk et al., Two distinct signaling pathways mediate DIF induction of prestalk gene expression in Dictyostelium, EXP CELL RE, 245(1), 1998, pp. 179-185
During Dictyostelium development, the differentiation inducing factor (DIF)
triggers expression of the prestalk gene ecmB and induces stalk cell diffe
rentiation, a form of programmed cell death. The effects of DIF are mediate
d by a sustained increase in cytosolic Ca2+ levels. The Ca2+ ATPase inhibit
or BHQ causes a similar rise in Ca2+ levels and also induces prestalk gene
expression. We show here that Ca2+ is a specific intermediate for prestalk
gene induction, since BHQ represses transcription of the cAMP-inducible agg
regative gene PDE, the postaggregative gene CP2, and the prespore gene D19.
The prestalk gene ecmA is also induced by DIF, but induction appears to oc
cur in two steps, which occur within 1 h and after 2 h, respectively. The s
low step shows the same kinetics as ecmB induction and similar to ecmB indu
ction, this step is BHQ inducible and requires an initial round of protein
synthesis. The fast step does not require protein synthesis and cannot be i
nduced by BHQ. This indicates that in addition to the slow Ca2+-mediated pa
thway, there is probably a second fast Ca2+-independent signal transduction
pathway for DIF. (C) 1998 Academic Press.