Structural and mechanistic basis of tunnelling nanotube mediated intercellular mitochondrial transfer

Biological tissues have traditionally been viewed as assemblies of autonomous cells but emerging evidence shows that fundamental organelles can be dynamically shared between cells, reshaping tissues into integrated, responsive systems rather than isolated cellular units. In particular, intercellular mitochondrial transfer (IMT) has been shown to occur both physiologically during development and pathologically in cancer. One of the major pathways by which this happens is via tunnelling nanotubes (TNTs), long actin-based cellular protrusions that connect the cytoplasm of neighbouring cells. Despite the widespread implications of TNT-mediated IMT, the structural and mechanistic basis of this phenomenon is largely uncharacterised, creating a major bottleneck in the field. I will address these gaps in knowledge by firstly using cryo-FIB milling and cryo-ET to investigate the architecture of the mitochondrial transport machinery in TNTs and the structural basis of cell-TNT junctions. Secondly, I will leverage an IMT assay I developed to identify the signalling pathways that induce TNT-mediated IMT. Finally, I will characterise the in vivo functions of TNT-mediated IMT during zebrafish development. Together, this project will establish the fundamental principles of TNT-mediated IMT, changing our understanding of cells as autonomous units and laying the groundwork for therapeutic exploitation of this phenomenon.