Identification of the regulatory elements controlling the transmission stage-specific gene expression of PAD1 in Trypanosoma brucei.
Trypanosomatid parasites provide an extreme model for the posttranscriptional control of eukaryotic gene expression. However, most analysis of their differential gene regulation has focussed on comparisons between life-cycle stages that exist in the blood of mammalian hosts and tsetse flies, the parasite's vector. These environments differ acutely in their temperature, and nutritional, metabolic and molecular composition. In the bloodstream, however, a more exquisitely regulated developmental step occurs: the production of transmissible stumpy forms from proliferative slender forms. This transition occurs in the relatively homogenous bloodstream environment, with stumpy-specific gene expression being repressed until accumulation of a proposed parasite-derived signal, stumpy induction factor. Here, we have dissected the regulatory signals that repress the expression of the stumpy-specific surface transporter PAD1 in slender forms. Using transgenic parasites capable of stumpy formation we show that PAD1-repression is mediated by its 3'-untranslated region. Dissection of this region in monomorphic slender forms and pleomorphic slender and stumpy forms has revealed that two regulatory regions co-operate to repress PAD1 expression, this being alleviated on exposure to SIF in pleomorphs or cAMP analogues that act as stumpy induction factor mimics in monomorphs. These studies identify elements that regulate trypanosome gene expression during development in their mammalian host.
Centre for Immunity, Infection and Evolution, Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, King's buildings, West Mains Road, Edinburgh, EH9 3JTU, UK.
Paula
P
MacGregor
Keith R
KR
Matthews
D020413:3' Untranslated Regions; D000818:Animals; D018507:Gene Expression Regulation, Developmental; D020868:Gene Silencing; D026901:Membrane Transport Proteins / Q000235:genetics*; D051379:Mice; D026723:Polyadenylation; D015800:Protozoan Proteins / Q000235:genetics*; D038621:Regulatory Sequences, Ribonucleic Acid; D014346:Trypanosoma brucei brucei / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
D020413:3' Untranslated Regions; D026901:Membrane Transport Proteins; D015800:Protozoan Proteins; D038621:Regulatory Sequences, Ribonucleic Acid