Specific cell—cell contacts are essential for induction of gene expression during differentiation of Dictyostelium discoideum

Publisher Website
Google Scholar
Abstract
Postaggregation D. discoideum cells contain 2000-3000 mRNA species that are absent from pre-aggregation cells. These aggregation-dependent sequences compose 30% of the mass of the late mRNA and represent the transcription products of an additional 11% of the single-copy genome. By analysis of mutants that are blocked at different stages of differentiation, it was shown that induction of expression of these genes is correlated with the formation of tight cell-cell contacts that resist EDTA. In particular, mutants that exhibit chemotaxis and aggregate to form loose mounds but do not form cell-cell contacts that resist EDTA fail to induce these late mRNA and protein species. By contrast, mutants that form normal contacts but progress no further through development do express the late mRNA species. Thus, interactions at the cell sorface are involved in developmental induction of a large group of coregulated mRNA. Two independent assays for these developmentally regulated mRNAs were used: hybridization of gel-separated RNA to cloned nuclear DNA and hybridization of mRNA to a cDNA probe specific for the population of 2000-3000 regulated sequences.