Mechanisms Controlling Gene Expression in Trypanosomatids
Pp. 261-290 (30)
Santuza M. R. Teixeira and Bruna M. Valente
As members of a highly divergent group of eukaryotes, trypanosomatids
present peculiar mechanisms of gene expression. These protozoan parasites have
transcription and processing machineries that constitutively transcribe clusters of nonrelated
genes into polycistronic pre-mRNAs, which are subsequently trans-spliced into
monocistronic transcripts. Because of this, control of gene expression relies mainly on
post-transcriptional mechanisms that are, for the most part, mediated by RNA binding
proteins that control steady-state levels of mRNAs and/or their translation rates. Using
primarily Trypanosoma brucei as a model, several groups have begun to elucidate the
basic regulatory mechanisms and to define the cellular factors controlling transcription,
processing, degradation and translation of mRNAs in trypanosomatids. This chapter
describes studies that have been focused on a subset of genes that are differentially
expressed during the life cycle of T. brucei, T. cruzi and few species of Leishmania.
Although a predominance of regulatory pathways acting at a post-transcriptional level
is found for most genes from all three parasites, it is also evident that the regulatory
strategies chosen by different trypanosomatid species are not similar. Because of their
complex and diversified gene regulatory machinery, T. brucei, T. cruzi and Leishmania
spp. are able to respond rapidly to the drastic environmental changes they face during
their life cycle, particularly when they move between their different hosts.
Epigenetics, Gene expression, Polyadenylation, Post-transcription,
RNA polymerase, RNA promoter, Trans-splicing, Transcription, Untranslated
Departamento de Bioquímica e Imunologia – ICB, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.