Although Myc transcription factors are extensively studied in the context of cancer, the inclusion of cMyc as one of the Yamanaka factors has renewed research into their roles in stem cell maintenance and embryogenesis. Myc is expressed throughout embryogenesis, but its spatiotemporal distribution has been poorly characterised. In this study, Kim Dale and colleagues sought to clarify the expression and function of Myc during early embryogenesis in mice, focussing on its role in body axis elongation and somite formation. The authors combine pharmacological inhibition and conditional loss-of-function genetic approaches to interrogate the role of Myc genes in the differentiation of neuromesodermal progenitors (NMPs) – a progenitor population that gives rise to posterior neural and mesoderm lineages. Their results show that cMyc is indeed required for the proper timing of somite formation through the regulation of Notch signalling. Additionally, they demonstrate that Myc operates in a positive feedback loop with WNT and FGF signalling in NMPs to facilitate axial elongation and to maintain accurate timing of the segmentation clock. This work places Myc activity at the centre of a signalling circuit that coordinates body axis elongation during embryogenesis.
