Cell-autonomous integrin control of Wnt and Notch signalling during somitogenesis

Integrins act at signalling crossroads, and their interactions with other signal transduction pathways are key to the regulation of normal and pathological cell cytoarchitecture and behaviour. Here, we describe a signalling cascade that acts during the formation of the defining segmental features of the vertebrate body - the somites - in which. beta 1-integrin activity regulates epithelialisation by controlling downstream Wnt and Notch activity crucial for somite border formation. Using in vivo transcriptional inhibition in the developing chick embryo, we show that. beta 1-integrin in the anterior presomitic mesoderm activates canonical Wnt signalling in a cell-autonomous, 'outside-inside' manner. Signalling is mediated by integrin-linked kinase ( ILK), leading to modulation of glycogen synthase kinase 3 beta (GSK3 beta) phosphorylation, and activates Notch signalling in the anterior presomitic mesoderm. The two signalling pathways then cooperate to promote somite formation via cMESO1/Mesp2. Our results show that. beta 1-integrin can regulate cell shape and tissue morphogenesis indirectly, by regulation of downstream signalling cascades.