Cell-cell contact, cyclic amp, and gene expression during development of dictyostelium discoideum

Dictyostelium discoideum exhibits many features of development seen in more complex eukaryotic organisms: specific cell–cell contacts are found; a homogeneous cell population differentiates into discrete cell types; and there is specific cell migration and pattern formation. These morphogenetic changes are accompanied by major changes in the pattern of gene expression. This chapter discusses the transcription of these genes, which is controlled by many of the same factors that affect gene expression in other differentiating systems, in particular, by cell- cell contact and by an extracellular hormone, cyclic AMP. Cell–cell contact in Dictyostelium is essential for stabilizing a large class of regulated mRNAs. cAMP also induces or accelerates at least part of the developmental program and may also induce the cytodifferentiation and segregation of prestalk and prespore cells. cAMP increases the synthesis and the stability of the 2500 mRNA species that are induced at aggregation; addition of this compound to disaggregated cells restores synthesis of these mRNAs.