Authors

L Glover¹;  ¹ Trypanosome Molecular Biology Unit, Institut Pasteur, Université Paris Cité, INSERM U1347, France

Discussion

Trypanosoma brucei undergoes a complex series of developmental transitions within the tsetse fly, culminating in mammalian infectivity acquisition in the salivary glands. Trypanosomes adapt to successive tissue niches through extensive transcriptional reprogramming and surface coat remodelling across at least nine life-cycle stages in the fly. Our work has begun to integrate single-cell technologies like CITE-seq (Cellular Indexing of Transcriptomes and Epitopes by Sequencing), which reveal population heterogeneity during T. brucei development, with functional analyses of specific genes to causally link molecular regulators to surface remodelling and infectivity. CITE-seq on trypanosomes recovered from infected tsetse flies showed GPEET restricted to a small subset of midgut procyclics and EP procyclins peaking in early proventricular forms alongside EP2 transcripts. Inverse relationships between EP protein abundance and specific kinases/phosphatases suggest phosphorylation dynamics regulate surface remodelling. Functional analyses of key regulators like VEX1 further deepen this framework: disrupting VEX1, a key VSG exclusion factor during metacyclic-to-bloodstream differentiation alters VSG expression and perturbs cell cycle-linked chromatin organization. These findings reveal that surface protein expression through development establishment is tightly coupled to broader nuclear regulatory programs.