Biology subjects

Urbaniak, M. D.

Publications and source records attributed to Urbaniak, M. D..

5 recordsLinked to original sources

bioRxiv2026

Adaptive metabolic reprogramming of the brain tissue during late-stage Trypanosoma brucei infection maintains host learning and memory

Human African Trypanosomiasis (HAT) is a two-stage infection caused by Trypanosoma brucei ssp. In stage I the trypanosomes are in blood, lymph and tissue interstitial space and the infection progresses to stage II when the parasites enter the central nervous system (CNS), resulting in behavioural aberrations that proceed to coma and death. Here, we use a bioluminescent murine model of HAT to examine parasite localisation and the changes in host brain gene expression, metabolism and function, and behaviour that occur over the course of the infection. The murine HAT model reproduces the decrease in brain tryptophan seen in clinical samples, and we report for the first time an unprecedented 1.8-fold decrease in global brain glucose metabolism in stage II infection. These metabolic changes are accompanied by an 18-fold decrease in brain insulin transcripts without changes in pathways regulating the cellular responses to insulin. By contrast, genes involved in fatty acid and lipid metabolism are upregulated in the brain during stage II infection. Moreover, we show that transcriptional programmes regulating mitochondrial metabolism dynamically adapts across the time course of HAT infection, ultimately leading to a transcriptional programme that diverts host brain metabolism away from glycolysis during stage II infection. Overall, our data demonstrate a reprogramming of brain energy metabolism during stage II HAT infection that favours the utilization of fatty acids and lipids to meet the energy demands of the brain, with a reduced reliance on glucose metabolism. Despite the profound neurometabolic changes observed, host anxiety-like behaviour is unchanged and episodic learning and memory is not impaired, suggesting that brain metabolic reprogramming enables the utilisation of adipose reserves to maintain core brain functions. These finding may explain the progressive onset of neurological symptoms in HAT patients and inform the development therapeutic interventions to alleviate them. Author SummaryHuman African Trypanosomiasis is classically characterised as being a two-stage infection, stage I where the extracellular Trypanosoma brucei multiply in the blood, lymph and peripheral tissues, and stage II where parasite cross the blood-brain barrier (BBB) causing neurological symptoms and eventually death. Using a murine model of HAT we show that in stage II the key brain metabolite tryptophan is depleted and cerebral glucose utilisation is decreased, accompanied by extensive metabolic transcriptome reprogramming of the cerebral tissue during stage II infection. Despite this we see no significant change in mouse anxiety-like behaviour or learning and memory. Our data are consistent with the brain switching from glucose as the primary energy source, instead utilising the products of lipolysis to maintain essential brain functions. This new understanding of the neurometabolic changes that occur in stage II HAT may help to develop new treatments for the neurological symptoms that affect patients at this stage of the disease.

immunology↗

bioRxiv2022

Single locus phosphoproteomics reveals phosphorylation of RPA-1 is required for generation of single-strand DNA following a break at a subtelomeric locus.

Damage to the genetic material of the cell poses a universal threat to all forms of life. Central to the DNA damage response (DDR) is a phosphorylation signalling cascade that leads to the co-ordination of the cellular response to a DNA break. Identifying the proteins that are phosphorylated is crucial to understanding the mechanisms underlying this DDR. We have used SILAC-based quantitative phosphoproteomics to profile changes in phosphorylation site abundance following a single double strand break (DSB) at a chromosome internal locus and the subtelomeric bloodstream form expression site in Trypanosoma brucei. We report >6500 phosphorylation sites, including a core set of 211 DSB responsive phosphorylation sites. Along with phosphorylation of canonical DNA damage factors, we find that there is a striking distinction between the proteins phosphorylated in response to a chromosome internal DSB and one at the active BES and describe a single phosphorylation event on Replication factor A (RPA) 1 that is required for efficient resection at a bloodstream form expression site.

molecular biology↗

bioRxiv2020

Phosphoproteomic analysis of mammalian infective Trypanosoma brucei subjected to heat shock suggests atypical mechanisms for thermotolerance

The symptoms of African sleeping sickness, caused by the parasite Trypanosoma brucei, can include periods of fever as high as 41 {degrees}C which triggers a heat shock response in the parasite. To capture events involved in sensing and responding to heat shock in the mammalian infective form we have conducted a SILAC-based quantitative proteomic and phosphoproteomic analysis of T. brucei cells treated at 41 {degrees}C for 1h. Our analysis identified 193 heat shock responsive phosphorylation sites with an average of 5-fold change in abundance, but only 20 heat shock responsive proteins with average of 1.5-fold change. These data indicate that protein abundance does not rapidly respond ([≤]1 h) to heat shock, and that the changes observed in phosphorylation site abundance are larger and more widespread. The heat shock responsive phosphorylation sites showed enrichment of RNA binding proteins with putative roles in heat shock response included P-body / stress granules and the eukaryotic translation initiation 4F complex. The ZC3H11-MKT1 complex, which stabilises mRNAs of thermotolerance proteins, appears to represent a key signal integration node in the heat shock response.

cell biology↗

bioRxiv2019

Organising the cell cycle in the absence of transcriptional control: Dynamic phosphorylation co-ordinates the Trypanosoma brucei cell cycle post-transcriptionally

The cell division cycle of the unicellular eukaryote Trypanosome brucei is tightly regulated despite the paucity of transcriptional control that results from the arrangement of genes in polycistronic units and lack of dynamically regulated transcription factors. To identify the contribution of dynamic phosphorylation to T. brucei cell cycle control we have combined cell cycle synchronisation by centrifugal elutriation with quantitative phosphoproteomic analysis. Cell cycle regulated changes in phosphorylation site abundance (917 sites, average 5-fold change) were more widespread and of a larger magnitude than changes in protein abundance (443 proteins, average 2-fold change) and were mostly independent of each other. Hierarchical clustering of co-regulated phosphorylation sites according to their cell cycle profile revealed that a bulk increase in phosphorylation occurs across the cell cycle, with a significant enrichment of known cell cycle regulators and RNA binding proteins (RBPs) within the largest clusters. Cell cycle regulated changes in essential cell cycle kinases are temporally co-ordinated with differential phosphorylation of components of the kinetochore and eukaryotic initiation factors, along with many RBPs not previously linked to the cell cycle such as eight PSP1-C terminal domain containing proteins. The temporal profiles demonstrate the importance of dynamic phosphorylation in co-ordinating progression through the cell cycle, and provide evidence that RBPs play a central role in post-transcriptional regulation of the T. brucei cell cycle.\n\nData are available via ProteomeXchange with identifier PXD013488.

cell biology↗

bioRxiv2018

Dynamic regulation of the Trypanosoma brucei transferrin receptor in response to iron starvation is mediated via the 3UTR

The bloodstream form of the parasite Trypanosoma brucei obtains iron from its mammalian host by receptor-mediated endocytosis of host transferrin through its own unique transferrin receptor (TbTfR). Expression of TbTfR rapidly increases upon iron starvation by post-transcriptional regulation through a currently undefined mechanism that is distinct from the mammalian iron response system. We have created reporter cell lines by fusing the TbTfR 3'UTR or a control Aldolase 3UTR to reporter genes encoding GFP or firefly Luciferase, and inserted the fusions into a bloodstream form cell line at a tagged ribosomal RNA locus. Fusion of the TbTfR 3UTR is sufficient to significantly repress the expression of the reporter proteins under normal growth conditions. Under iron starvation conditions we observed upregulation of the TbTfR 3UTR fusions only, with a magnitude and timing consistent with that reported for upregulation of the TbTfR. We conclude that the dynamic regulation of the T. brucei transferrin receptor in response to iron starvation is mediated via its 3UTR, and that the effect is independent of genomic location.

cell biology↗