Neural Crest Specification requires cytoneme-dependent Wnt signalling

Intercellular communication is fundamental to the functionality of all multicellular organisms. This complex process underpins embryonic development, allowing a fertilised egg to differentiate into a whole organism and facilitating adult tissues in their response and adaptation to injury. Cellular signalling mechanisms involve the transmission of molecular signals that orchestrate transcriptional and behavioural changes in recipient cells.
Traditional paradigms suggest that signalling ligands are secreted by source cells and diffuse through the extracellular space to bind receptors on target cells. Although such a mechanism can explain some signalling processes, it fails to explain how specific cells in a progenitor population can be targeted or a precise temporal regulation of signalling can be achieved. Emerging evidence has started to change our understanding of dissemination mechanisms, revealing the existence of cytonemes for cell-to-cell communication. These actin-based cellular threads extend from the signalling cell, enabling precise targeting by delivering molecular signals with high specificity and efficiency over multiple cell diameters to the receiving cell. In a further unexpected twist, we find that cytonemes also transfer pre-formed and active ligand-receptor complexes to target cells to uncouple the endogenous presence of receptors and to increase the signal-to-noise ratio.
Neural crest (NC) is an essential cell population in vertebrates that gives rise to, for example, skin pigment cells, peripheral nervous system (PNS), and facial bones. The formation of NC in embryogenesis is characterised by the induction and subsequent migration of a multipotent cell population from the dorsal margin of the neural tube. This process is orchestrated by a sophisticated interplay of external cues and transcriptional networks, which guide the NC cells through their multipotent journey, enabling them to adopt all the diverse cellular fates. The external cues...