Project description:Pre mRNA 3 end processing is unique in trypanosomes as it involves polycistronic transcription, polyadenylation coupled to trans splicing and elusive polyadenylation signals. The mechanism is poorly understood. Here we reported that nine putative polyA factors from Trypanosoma brucei form a stable complex which then subsequently develops into two tight subcomplexes. One contains the proteins tbCPSF160, tbCPSF30, tbFip1 and tbWdr33 with tbCPSF160 as the scaffold; while the other contains tbCPSF100, tbCPSF73, tbSYMK and two trypanosome unique proteins, designated CPF30 and CPF15. No CstF homologs were found. The protein tbCPSF100 seems to coordinate the association of these two subcomplexes by interacting with tbCPSF160. RNAi knockdown of these polyA factors resulted in RNA processing disorders and variable disruption of the complex and RNA processing disorders. Depletion of either factors caused dicistronic transcripts formation; depletion of either tbCPSF30, tbFip1 or tbWdr33 caused increased usage of proximal polyadenylation sites of the transcripts; depletion of tbCPSF30 caused mRNA polyA tail shortening. This indicates that these two polysA factors have a critical role in polyadenylation site selection. Genome-wide UV crosslinking assays showed that tbCPSF30 and tbFip1 have strong RNA-binding activity in this complex. Altogether, these data indicate that the 3 end processing complex of T. brucei is more like the human CPSF homolog. However, it displays trypanosome specific features in composition, structural assembly and function of components, which facilitate a common, yet unique, cleavage polyadenylation reaction.
Project description:In this study we investigate the function of RBP10, and present evidence that the presence of RBP10 is sufficient to induce the expression of mRNAs involved in bloodstream-form energy metabolism.
Project description:The African trypanosome Trypanosoma brucei is a unicellular eukaryote, which relies on a protective Variant Surface Glycoprotein (VSG) coat for survival in the mammalian host. A single trypanosome has >2000 VSG genes and pseudogenes of which only one is expressed from one of ~15 telomeric bloodstream form expression sites (BESs). Infectious metacyclic trypanosomes present within the tsetse fly vector also express VSG from a separate set of telomeric metacyclic ESs (MESs). All MESs are silenced in bloodstream form T. brucei. As very little is known about how this is mediated, we performed a whole genome RNAi library screen to identify MES repressors. This allowed us to identify a novel SAP domain containing DNA binding protein which we called TbSAP. TbSAP is enriched at the nuclear periphery and binds both MESs and BESs. Knockdown of TbSAP in bloodstream form trypanosomes did not result in cells becoming more ‘metacyclic’-like. Instead, there was extensive global upregulation of transcripts including MES VSGs, VSGs within the silent VSG arrays as well as genes immediately downstream of BES promoters. TbSAP therefore appears to be a novel architectural chromatin protein playing an important role in silencing the extensive VSG repertoire of bloodstream form T. brucei.
Project description:In this study we investigate the function of RBP10, and present evidence that the presence of RBP10 is sufficient to induce the expression of mRNAs involved in bloodstream-form energy metabolism. for BS RBP10 RNAi Samples: total of 6 slides, including 3 biological replicates and dyeswap for RBP10 overexpression Samples: total of 5 slides, including 3 biological replicates and dyeswap
Project description:Different strains of T. brucei induce different degrees of pathology in infected animals, and TREU927-infected mice display greater splenomegaly and anaemia than 247-infected mice. The analysis of differential host gene expression in infected spleens has allowed the identification of which pathways or processes are crucial in determining the progression of disease, for example IL10, LXR/RXR activation and alternative macrophage activation. We used microarray analysis to examine host gene expression between uninfected and infected mice, and between mice infected with the two trypanosome strains.
Project description:Here, we produced a series of monomorphic trypanosome stocks, creating snapshots of the transition from pleomorphism to monomorphism, by continuous rapid syringe-passage in mice using a pleomorphic T. brucei. We then compared the transcriptomes of these artificial monomorphic trypanosomes, alongside several naturally monomorphic T. evansi and T. equiperdum strains, with the pleomorphic T. brucei, to analysis the causes of the monomorphism. Trypanosomes grown in mice were harvested at different stage post infection depend on strains (Detailed information was descrided in overall design), and mRNA profile of each sample was generated by deep sequencing, in triplicate.
