Showing papers by "Pauline Schaap published in 1988"
TL;DR: It is concluded that extracellular cAMP is the major morphogenetic signal for the differentiation of prespore cells in the multicellular stages of D. discoideum development and a working hypothesis is presented for the generation of the prestalk/prespore pattern during multicesllular development.
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 extracellular 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.
60 citations
TL;DR: This work investigated the expression of the cAMP chemotactic system during development of synchronized E and L cells and found that E cells exhibit cAMP-binding activity, cell surfacecAMP-phosphodiesterase (mPDE) activity, and the ability to relay cAMP signals at least 2 hr earlier and to higher levels than L cells.
54 citations
TL;DR: The results indicate that two divergent pathways transduce the extracellular cAMP signal to, respectively, prestalk and prespore gene expression.
Abstract: We investigated the effect of LiCl on pattern formation and cAMP-regulated gene expression in Dictyostelium discoideum. In intact slugs, 5 mM LiCl induces an almost complete redifferentiation of prespore into prestalk cells. We found that LiCl acts by interfering with the transduction of extracellular cAMP to cell-type-specific gene expression; LiCl inhibits the induction of prespore-specific gene expression by cAMP, while it promotes the induction of prestalk-associated gene expression by cAMP. Our results indicate that two divergent pathways transduce the extracellular cAMP signal to, respectively, prestalk and prespore gene expression.
46 citations
TL;DR: Observations indicate that receptor down-regulation involves receptor agglomeration and suggest that receptordown-regulation takes place in vivo, when tight aggregates are being formed, as well as suggesting that cAMP binding activity decreases during tight aggregate formation.
39 citations
TL;DR: It is suggested that the transduction of extracellular cAMP to prespore gene or prestalk gene expression occurs via divergent pathways and the involvement of two different adenosine target sites is suggested.
19 citations