The differentially expressed translationally controlled tumor proteins TCTP1 and TCTP2 in Trypanosoma brucei

Abstract

1. SummaryIn Trypanosoma brucei we identified two TCTP genes differentially expressed during the parasite life cycle and discovered the mechanism by which this expression is controlled. Furthermore, we demonstrate that TCTP is important for cell growth as well as proper cell and organelle morphology in the insect form of the parasite.\n\n2. AbstractTCTP is a highly conserved protein ubiquitously expressed in eukaryotes. Studies have reported TCTP to be involved in growth and development, cell cycle progression, protection against cellular stresses and apoptosis, indicating the multifunctional role of the protein. Here, for the first time we characterize the expression and function of TCTP in the unicellular parasite Trypanosoma brucei. We identified two paralogue TCTP genes, which we named TbTCTP1 and TbTCTP2. They have identical 5UTRs and only ten single nucleotide polymorphisms in the open reading frames (ORFs). However, the 3UTRs differ dramatically in sequence and length. We found that the two TCTP mRNAs are differentially expressed during T. brucei life cycle. While procyclic form trypanosomes (PCF) express TCTP1, the bloodstream form trypanosomes (BSF), express TCTP2. We link the differential expression to the distinct 3UTRs of the paralogues. In PCF cells, the protein appears to localize in the cytosol. We show that TCTP1 is essential for normal cell growth and has pleiotropic effects on the cells including aberrant cell morphology, enlarged and reduced number of acidocalcisomes and appearance of accumulations in the mitochondria.