The molecular coordinate system of the planarian body plan

How developing tissues, organs and entire animals grow to their precise size and shape remains one of the big questions in biology. Our approach combines experiment and theory, for which the food-dependent scaling of planarian body size or the precise control over size or geometry of amputation fragments provide ideal preconditions. On the experimental side, we screen for size and shape related signaling pathways using RNAseq and RNAi and we dissect the molecular regulation of known patterning pathways (e.g., Wnt signaling in the tail). We raise antibodies and develop staining protocols to visualize and quantify pathway activity in the tissue during regeneration and at steady state. On the theory side, we collaborate closely with the groups of Frank Jülicher at the MPI-PKS and Lutz Brusch at the TUD to understand the quantitative interplay between signaling pathway activity and tissue dimensions or how feedback between signaling pathways gives rise to a self-organizing molecular coordinate system.

Left: Gene expression patterns of signaling pathway components with graded expression along the A/P axis. Members of the Nou-Darake family of FGF-antagonists are shown on top, tail-expressed Wnt-ligands below (from Gurley et al., 2010). Centre: Computational simulations of cell-based polarity propagation (left) or the formation of Turing patterns (right). Images courtesy of Lutz Brusch, Brusch group. Right: Ectopic head induction by beta-Catenin-1(RNAi).