Cyclic AMP–phosphodiesterase induces dedifferentiation of prespore cells in Dictyostelium discoideum slugs: evidence that cyclic AMP is the morphogenetic signal for prespore differentiation

Abstract

Abstract We investigated whether cyclic AMP is an essential extracellular stimulus for the differentiation of prespore cells in slugs of D. discoideum. A local reduction of the extracellular cAMP level inside the slug was induced by implantation of cAMP-phosphodiesterase (cAMP-PDE)-coated spheres in intact slugs. This treatment caused the disappearance of prespore antigen in the vicinity of the sphere. A general reduction of extracellular cAMP levels in slugs, induced by submerging slugs in 0·25i.u.ml−1 cAMP-PDE, reduced the proportion of prespore cells from 66 % to 15 %, without affecting slug morphology. The cAMP-PDE-induced dedifferentiation of prespore cells was counteracted by cAMP and was not due to the production of the hydrolysis product 5′AMP, but to the reduction of extracellular cAMP levels. We conclude that extra-cellular cAMP is the major morphogenetic signal for the differentiation of prespore cells in the multicellular stages of D. discoideum development and we present a working hypothesis for the generation of the prestalk/ prespore pattern during multicellular development.