Temporally and Spatially Regulated Collagen XVIII Isoforms Impact Ureteric Patterning Through Their TSP1-like Domain

Collagen XVIII (ColXVIII) is a component of the extracellular matrix implicated in embryogenesis and control of homeostasis. We provide evidence that ColXVIII has a specific role in kidney ontogenesis by regulating the interaction between mesenchymal and epithelial tissues as observed in analyses of total and isoform-specific knockout embryos, mice, and ex vivo organ primordia. ColXVIII deficiency, both temporally and spatially, impacts the 3D pattern of ureteric tree branching morphogenesis via its specific isoforms. Proper development of ureteric tree depends on a tight control of the nephron progenitor cells (NPCs). ColXVIII-deficient NPCs are leaving the NPC pool faster than in controls. Moreover, the data suggests that ColXVIII mediates the kidney epithelial tree patterning via its N-terminal domains, and especially the Thrombospondin-1-like domain, and that this morphogenetic effect involves ureteric epithelial integrins. Altogether, the results propose a significant role for ColXVIII in a complex signalling network regulating renal progenitors and kidney development.