Project description:The ability to adapt to varying nutrient availability in changing environments is critical for successful parasitism. The lifecycle stages of the African trypanosome, Trypanosoma brucei, that infect the host mammalian bloodstream utilize glucose exclusively for ATP production. The finding that trypanosomes also inhabit other tissues that frequently contain lower glucose concentrations suggests blood stage parasites may have to respond to a dynamic environment with changing nutrient availability in order to survive. However, little is known about how the parasites coordinate gene expression with nutrient availability. Through transcriptome analysis, we have found blood stage parasites deprived of glucose alter gene expression in a pattern similar to transcriptome changes triggered by other stresses. A surprisingly low concentration of glucose (<10 μM) was required to initiate the response. To further understand the dynamic regulation of gene expression that occurs in response to altered glucose availability in the environment, we have interrogated the 3’UTR of cytochrome c oxidase subunit VI, a known lifecycle stage regulated gene, and have identified a stem-loop structure that confers glucose-responsive regulation at the translational level.
Project description:The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to Trypanosoma brucei brucei but not the human sleeping sickness parasite Trypanosoma brucei rhodesiense. It is thought that T. b. rhodesiense evolved from a T. b. brucei-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant T. b. brucei. Here we show that conversion of T. b. brucei from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (SRA) of T. b. rhodesiense. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (ESAG) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by T. b. brucei. Keywords: Trypanosoma, VSG, antigenic switching, HDL-resistance
Project description:Trypanosoma brucei gambiense is the causative agent of the fatal human disease African sleeping sickness. Using Digital Gene Expression we have compared the transcriptome of a group 1 T.b.gambiense (Eliane) and a T.b.brucei (STIB 247).
Project description:The immortalized mouse hypothalamic cell line N25/2 was treated with medium containing amino acids or medium lacking all amino acids for 1, 2, 3, 5 or 16 hours, and the gene expression was measured for 28270 genes using microarray. Numerous transporters from the SLC family were transcriptionally regulated in response to changed amino acid levels.