RNA-binding proteins and mRNA turnover in trypanosomes.

Trypanosomes, protozoan parasites of the order Kinetoplastida, control gene expression essentially through post-transcriptional mechanisms. Several motifs located mainly in the 3' untranslated region, such as AU-rich elements (AREs), were recently shown to modulate mRNA half-life, and are able to modify mRNA abundance in vivo through the interaction with specific RNA-binding proteins. Along with the detection of an active exosome, decapping activities and a regulated 3' to 5' exonuclease activity stimulated by AREs, these results suggest that modulation of mRNA stability is essential in trypanosomes. These regulatory processes are specific for different developmental stages and thus relevant for allowing trypanosomes to adapt to variable environmental conditions.