Spatiotemporal proteomics reveals dynamic antiparallel gradients shaping signalling waves

Embryonic development is driven by dynamic protein networks, yet how these dynamics shape morphogenesis remains poorly understood. Somitogenesis, the rhythmic segmentation of vertebrate embryos, is controlled by signalling gradients and oscillations in the presomitic mesoderm (PSM), but the underlying protein dynamics remain largely unknown. Here, we combine microfluidic synchronisation of mouse embryo tails with quantitative proteomics and transcriptomics to resolve spatiotemporal protein dynamics during somitogenesis. We identify proteins with dynamic expression during somitogenesis and reveal an antiparallel, dynamic R-Spondin/LGR signalling pattern that explains how Wnt oscillation amplitude increases despite declining Wnt ligand levels in the anterior PSM. Dynamic ligand expression is validated in mouse gastruloids, and perturbation of ligand dynamics reduces oscillation amplitude and impairs somite formation. Together, our findings identify R-Spondin as a dynamic amplifier of Wnt signalling oscillations and provide a mechanistic framework for understanding how protein dynamics regulate mammalian tissue patterning.