CONTROL OF GENE-EXPRESSION IN TRYPANOSOMATIDAE

The study of mechanisms which control gene expression in trypanosomati ds has developed at an increasing rate since 1989 when the first succe ssful DNA transfection experiments were reported. Using primarily Tryp anosoma brucei as a model, several groups have begun to elucidate the basic control mechanisms and to define the cellular factors involved i n mRNA transcription. processing and translation in these parasites. T his review focuses on the most recent studies regarding a subset of ge nes that are expressed differentially during the life cycle of three g roups of parasites. In addition to T. brucei, I will address studies o n gene regulation in a few species of Leishmania and the results obtai ned by a much more limited group of laboratories studying gene express ion in Trypanosoma cruzi. It is becoming evident that the regulatory s trategies chosen by different species of trypanosomatids are not simil ar, and that for these very successful parasites it is probably advant ageous to employ multiple mechanisms simultaneously. In addition, with the increasing numbers of parasite genes that have now been submitted to molecular dissection, it is also becoming evident that, among the various strategies for gene expression control, there is a predominanc e of regulatory pathways acting at the post-transcriptional level.