Regulation of mRNA stability and the poly(A) problem in Dictyostelium discoideum.

This paper reviews our studies of three aspects of post-transcriptional regulation in Dictyostelium discoideum: 1) the determinants of mRNA stability in vegetative amoebae; 2) the effects of disaggregation and cyclic AMP on the decay rates of cell-type-specific mRNAs in late developing cells; and 3) the cytoplasmic function of the 3' poly(A) tracts present on most mRNAs. We find that: 1) mRNA stability in vegetative amoebae is not dependent on mRNA size, ribosome loading, or poly(A) tract length, but may be determined by specific 3'-untranslated sequences within a given mRNA; 2) mRNA decay rates in late developing cells are heterogeneous, and cyclic AMP does not act directly to stabilize cell-type-specific mRNAs; and 3) poly(A) is most likely involved in the initiation of protein synthesis via an interaction with cytoplasmic poly(A)-binding proteins.