Expression of the RNA-binding protein RBP10 in Trypanosoma brucei promotes the bloodstream-form differentiation state, while its depletion forces differentiation into procyclic forms.
RBP10 acts as a regulatory switch in Trypanosoma brucei, promoting the bloodstream-form differentiation state by repressing procyclic-specific mRNAs.
In nearly all eukaryotes, cellular differentiation is governed by changes in transcription, and stabilized by chromatin and DNA modification. Gene expression control in the pathogen Trypanosoma brucei, in contrast, relies almost exclusively on post-transcriptional mechanisms, so RNA binding proteins must assume the burden that is usually borne by transcription factors. T. brucei multiply in the blood of mammals as bloodstream forms, and in the midgut of Tsetse flies as procyclic forms. We show here that a single RNA-binding protein, RBP10, promotes the bloodstream-form trypanosome differentiation state. Depletion of RBP10 from bloodstream-form trypanosomes gives cells that can grow only as procyclic forms; conversely, expression of RBP10 in procyclic forms converts them to bloodstream forms. RBP10 binds to procyclic-specific mRNAs containing an UAUUUUUU motif, targeting them for translation repression and destruction. Products of RBP10 target mRNAs include not only the major procyclic surface protein and enzymes of energy metabolism, but also protein kinases and stage-specific RNA-binding proteins: this suggests that alterations in RBP10 trigger a regulatory cascade.
Mugo et al. (Fri,) conducted a other in Trypanosoma brucei infection. RBP10 expression or depletion vs. Uninduced control cells was evaluated on Cellular differentiation state. Expression of the RNA-binding protein RBP10 in Trypanosoma brucei promotes the bloodstream-form differentiation state, while its depletion forces differentiation into procyclic forms.