A role for cAMP-dependent protein kinase in determining the stability of prespore cell differentiation in Dictyostelium.

When Dictyostelium slugs are disaggregated and shaken in suspension prespore mRNAs disappear from the cells very rapidly but in the presence of extracellular cAMP the loss of prespore mRNA sequences is retarded. In a mutant which lacks a functional regulatory subunit of the cAMP-dependent protein kinase (PKA), and where the catalytic subunit is thereby rendered constitutively active, two prespore mRNA sequences persist for extended times after cellular disaggregation. Thus PKA is a component of the signaling pathway that allows prespore cells rapidly to dedifferentiate when extracellular cAMP signaling is disrupted. Analysis of cells expressing a dominant inhibitor of PKA shows there to be both a PKA-requiring and a non-PKA-requiring intracellular signaling pathway directing prespore-specific gene transcription and suggests that there may also be post-transcriptional regulation by PKA.