Mechanistic interrogation of amoeboid T cell migration reveals a novel role for the VPS34-PIKfyve pathway in the regulation of cell speed

This thesis explores the intricate regulatory mechanisms governing amoeboid cell migration. It follows a cumulative format, beginning with an introduction, followed by a section delineating the aims of this thesis. The results chapter is divided into four sections (Sections I-IV), comprising a preprint, a set of unpublished data, and two published research articles. The final chapter, "Conclusion & Future Perspectives" relates the presented findings to a broader context and outlines possible directions for future studies.
In the results Section I, titled “Engagement of the VPS34–PIKfyve Axis at the Uropod Promotes Fast Amoeboid Migration”, we reveal a novel role of the VPS34–PIKfyve lipid kinase pathway on endo-lysosomes at the uropod of migrating T cells. The findings, detailed in a preprint accompanied by extended data, underscore the necessity of VPS34 and PIKfyve activity for rapid migration of T cells. VPS34 and PIKfyve promote myosin IIA and retrograde actin flow, which are critical for T cell propulsion. Notably, this effector function of the VPS34–PIKfyve axis on amoeboid migration speed is conserved across myeloid cells, and the social amoeba Dictyostelium discoideum. This section encapsulates the main outcomes of my doctoral research.
Section II of the results, titled “Interrogation of Chemokine-Induced Metabolism in Naïve CD8+ T cells”, unveils findings from an investigation into the chemokine-induced metabolic alterations in T cells in a set of unpublished data. These results elucidate alterations in glycolytic metabolism and mitochondrial respiration initiated by chemokines and provide first insights into the scope of chemokine-induced metabolic rewiring.
The results in Section III, titled “Acetate Modulates Memory CD8+ T Cell Effector Function, Survival, and Migration During Bacterial Infections”, contain a published manuscript that explores the modulatory effects of acetate on memory CD8+ T cell function during bacterial infections. In this context, an investigation unraveled an
inhibitory effect of acetate on the migration of memory CD8+ T cells in vitro, aligning with alterations in cell numbers at sites of acetate treatment in vivo.
Lastly, Section IV, titled “Development of a Volatile Metabolomics Platform for Dendritic Cells to Investigate Cellular Metabolism in Real-Time”, comprises a published manuscript describing the development of a platform capable of real-time monitoring of dendritic cell metabolism in the volatile phase. We demonstrate the ability of this novel experimental platform to discern varying metabolic states of dendritic cells and trace the incorporation of isotopically labeled glucose.