The epimastigote stage-specific gene expression of CESP is tightly regulated by its 3' UTR

It is known that gene expression in kinetoplastids is regulated post-transcriptionally. Although previous studies have shown that stage-specific gene expression in trypanosomes is regulated by cis-elements located in the 3' untranslated region (UTR) of mRNA and also by RNA binding proteins that use bloodstream and procyclic forms, no studies have been performed in the epimastigote form (EMF) of African trypanosomes. This study shows that the cis-elements of the congolense epimastigote-specific protein (cesp) gene regulate its EMF-specific expression. Four different egfp expression cassettes containing 5' and 3' UTRs derived from actin and cesp were integrated into the Trypanosoma congolense genome. EGFP expression was observed in EMF trypanosomes when the egfp cassette contained the cesp 3' UTR. These results indicate that the essential cis-element located in the cesp 3' UTR selectively stabilizes mRNA in the EMF stage and/or destabilized mRNA in other stages. This is the first report of post-transcriptional gene expression regulation in EMF African trypanosomes.